# Pathogenic hyperactivation of mTORC1 by cytoplasmic EP300 in Hutchinson-Gilford progeria syndrome

Lucille Ferret, Guido Kroemer, Mojgan Djavaheri-Mergny

► To cite this version:

Lucille Ferret, Guido Kroemer, Mojgan Djavaheri-Mergny. Pathogenic hyperactivation of mTORC1 by cytoplasmic EP300 in Hutchinson-Gilford progeria syndrome. Cell Stress, 2024, 8, pp.51-55. 10.15698/cst2024.04.295 . inserm-04601030

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Submitted on 4 Jun 2024

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# Pathogenic hyperactivation of mTORC1 by cytoplasmic EP300 in Hutchinson-Gilford progeria syndrome

Lucille Ferret, Guido Kroemer, Mojgan Djavaheri-Mergny

► To cite this version:

Lucille Ferret, Guido Kroemer, Mojgan Djavaheri-Mergny. Pathogenic hyperactivation of mTORC1 by cytoplasmic EP300 in Hutchinson-Gilford progeria syndrome. Cell Stress, 2024, 8, pp.51-55. 10.15698/cst2024.04.295 . inserm-04601030

HAL Id: inserm-04601030

https://inserm.hal.science/inserm-04601030v1

Submitted on 4 Jun 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# Pathogenic hyperactivation of mTORC1 by cytoplasmic EP300 in Hutchinson-Gilford progeria syndrome

Lucille Ferret<sup>1,2,3</sup>, Guido Kroemer<sup>1,2,4</sup> and Mojgan Djavaheri-Mergny<sup>1,2,*</sup>

Mojgan Djavaheri-Mergny, Centre de Recherche des Cordeliers, INSERM UMRS 1138, Sorbonne Université, Université Paris Cité, Équipe labellisée par la Ligue contre le Cancer, Institut universitaire de France, Paris, France; E-mail: mojgan.mergny@inserm.fr

In a recent issue in *Nature Cell Biology*, Sung Min Son et al. unveil a novel layer in the regulation of the mTORC1/autophagy axis by EP300 which can undergo nucleocytoplasmic shuttling in response to alterations in nutrient availability. The study highlights that, in Hutchinson-Gilford progeria syndrome, overabundant cytoplasmic EP300 results in mTORC1 hyperactivation and impaired autophagy, potentially contributing to premature and accelerated aging.

Mechanistic target of rapamycin complex 1 (mTORC1) is a multiprotein complex that serves as a pivotal regulator of cell growth, protein synthesis, metabolism and autophagy [1, 2]. This complex compromises mTOR (mechanistic target of rapamycin), RAPTOR (regulatory associated protein of mTOR), GβL (G protein β subunit-like protein)/mLST8 (mammalian lethal with SEC13 protein 8), DEPTOR (DEP-domain-containing mTOR interacting protein) and PRAS40 (40 kDa proline-rich Akt substrate). Overactivation of mTORC1 signaling is frequently associated with key processes associated with aging and age-related diseases [3, 4]. Conversely, life span extension occurs in various model species (such as worms, yeast, flies and mice) during continuous or intermittent inhibition of mTORC1 by genetic or pharmacological manipulations, respectively [5]. Apparently, this antiaging effect of mTORC1 deactivation is mediated through the induction of autophagy [5].

In a recent issue in *Nature Cell Biology*, Sung Min Son et al. [6] unveil a novel layer in the regulation of the mTORC1/autophagy axis by the acetyltransferase EP300 that is intricately linked to nucleocytoplasmic shuttling of

EP300. The study reveals that Hutchinson-Gilford progeria syndrome (HGPS), a disease associated with accelerated aging, may be explained by enhanced activity of cytoplasmic EP300, resulting in mTORC1 hyperactivation and impaired autophagy.

Several pathways regulate mTORC1 in response to nutrient status [2] (Fig. 1). Thus, the abundance of some amino acids (such as leucine and other branched chain amino acids) stimulate mTORC1 activity through EP300-dependent RAPTOR acetylation, a crucial step for the recruitment of cytoplasmic RAPTOR to Rag GTPase on lysosomal membranes [7]. This event facilitates mTORC1 translocation to the surface of lysosomes where it becomes active through its interaction with RHEB. Upon glucose withdrawal, or depletion of other sources of energy, adenosine monophosphate-dependent kinase (AMPK) is activated and represses mTORC1 activity either directly through phosphorylation of RAPTOR or indirectly by phosphorylating Tuberous Sclerosis Complex 2 (TSC2), which is an upstream regulator of mTORC1 [8, 9]. The consequent inhibition of mTORC1 activity then results in decreased phosphorylation of mTORC1 substrates including Unc-51-like autophagy-activating kinase 1 (ULK1), ultimately culminating in the initiation of autophagy [10].

While these findings underscore the critical role of EP300 in regulating mTORC1 activity in response to nutrient status, several questions have remained unanswered: Is EP300-mediated RAPTOR acetylation a rate limiting factor of mTORC1 activation in response to nutrient status? Does nucleocytoplasmic localization of EP300 influence mTORC1 activity? What is the impact of EP300-mediated mTORC1 activation on autophagy? How is this pathway

**Comment on** Son SM, Park SJ, Breusegem SY, Larrieu D, Rubinsztein DC (2024). EP300 nucleocytoplasmic shuttling underlies mTORC1 hyperactivation in Hutchinson-Gilford progeria syndrome. *Nat Cell Biol.* 26(2):235-249. doi: 10.1038/s41556-023-01338-y

doi: 10.15698/cst2024.04.295

Received originally: 15.03.2024, Accepted 20.03.2024, Published 30.04.2024.

Keywords: mTORC1, EP300, autophagy, aging.

<footnote n="1">¹Centre de Recherche des Cordeliers, INSERM UMRS 1138, Sorbonne Université, Université Paris Cité, Équipe labellisée par la Ligue contre le Cancer, Institut universitaire de France, Paris, France.</footnote>

<footnote n="2">²Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France.</footnote>

<footnote n="3">³Faculté de Médecine, Université de Paris Saclay, Paris, France.</footnote>

<footnote n="4">⁴Institut du Cancer Paris CARPEM, Department of Biology, Hôpital Européen Georges Pompidou, AP-HP, Paris, France.</footnote>

<footnote>* Corresponding Author:</footnote>
# Pathogenic hyperactivation of mTORC1 by cytoplasmic EP300 in Hutchinson-Gilford progeria syndrome

Lucille Ferret<sup>1,2,3</sup>, Guido Kroemer<sup>1,2,4</sup> and Mojgan Djavaheri-Mergny<sup>1,2,*</sup>

Mojgan Djavaheri-Mergny, Centre de Recherche des Cordeliers, INSERM UMRS 1138, Sorbonne Université, Université Paris Cité, Équipe labellisée par la Ligue contre le Cancer, Institut universitaire de France, Paris, France; E-mail: mojgan.mergny@inserm.fr

In a recent issue in *Nature Cell Biology*, Sung Min Son et al. unveil a novel layer in the regulation of the mTORC1/autophagy axis by EP300 which can undergo nucleocytoplasmic shuttling in response to alterations in nutrient availability. The study highlights that, in Hutchinson-Gilford progeria syndrome, overabundant cytoplasmic EP300 results in mTORC1 hyperactivation and impaired autophagy, potentially contributing to premature and accelerated aging.

Mechanistic target of rapamycin complex 1 (mTORC1) is a multiprotein complex that serves as a pivotal regulator of cell growth, protein synthesis, metabolism and autophagy [1, 2]. This complex compromises mTOR (mechanistic target of rapamycin), RAPTOR (regulatory associated protein of mTOR), GβL (G protein β subunit-like protein)/mLST8 (mammalian lethal with SEC13 protein 8), DEPTOR (DEP-domain-containing mTOR interacting protein) and PRAS40 (40 kDa proline-rich Akt substrate). Overactivation of mTORC1 signaling is frequently associated with key processes associated with aging and age-related diseases [3, 4]. Conversely, life span extension occurs in various model species (such as worms, yeast, flies and mice) during continuous or intermittent inhibition of mTORC1 by genetic or pharmacological manipulations, respectively [5]. Apparently, this antiaging effect of mTORC1 deactivation is mediated through the induction of autophagy [5].

In a recent issue in *Nature Cell Biology*, Sung Min Son et al. [6] unveil a novel layer in the regulation of the mTORC1/autophagy axis by the acetyltransferase EP300 that is intricately linked to nucleocytoplasmic shuttling of

EP300. The study reveals that Hutchinson-Gilford progeria syndrome (HGPS), a disease associated with accelerated aging, may be explained by enhanced activity of cytoplasmic EP300, resulting in mTORC1 hyperactivation and impaired autophagy.

Several pathways regulate mTORC1 in response to nutrient status [2] (Fig. 1). Thus, the abundance of some amino acids (such as leucine and other branched chain amino acids) stimulate mTORC1 activity through EP300-dependent RAPTOR acetylation, a crucial step for the recruitment of cytoplasmic RAPTOR to Rag GTPase on lysosomal membranes [7]. This event facilitates mTORC1 translocation to the surface of lysosomes where it becomes active through its interaction with RHEB. Upon glucose withdrawal, or depletion of other sources of energy, adenosine monophosphate-dependent kinase (AMPK) is activated and represses mTORC1 activity either directly through phosphorylation of RAPTOR or indirectly by phosphorylating Tuberous Sclerosis Complex 2 (TSC2), which is an upstream regulator of mTORC1 [8, 9]. The consequent inhibition of mTORC1 activity then results in decreased phosphorylation of mTORC1 substrates including Unc-51-like autophagy-activating kinase 1 (ULK1), ultimately culminating in the initiation of autophagy [10].

While these findings underscore the critical role of EP300 in regulating mTORC1 activity in response to nutrient status, several questions have remained unanswered: Is EP300-mediated RAPTOR acetylation a rate limiting factor of mTORC1 activation in response to nutrient status? Does nucleocytoplasmic localization of EP300 influence mTORC1 activity? What is the impact of EP300-mediated mTORC1 activation on autophagy? How is this pathway

**Comment on** Son SM, Park SJ, Breusegem SY, Larrieu D, Rubinsztein DC (2024). EP300 nucleocytoplasmic shuttling underlies mTORC1 hyperactivation in Hutchinson-Gilford progeria syndrome. *Nat Cell Biol.* 26(2):235-249. doi: 10.1038/s41556-023-01338-y

doi: 10.15698/cst2024.04.295

Received originally: 15.03.2024, Accepted 20.03.2024, Published 30.04.2024.

Keywords: mTORC1, EP300, autophagy, aging.

<footnote n="1">¹Centre de Recherche des Cordeliers, INSERM UMRS 1138, Sorbonne Université, Université Paris Cité, Équipe labellisée par la Ligue contre le Cancer, Institut universitaire de France, Paris, France.</footnote>

<footnote n="2">²Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France.</footnote>

<footnote n="3">³Faculté de Médecine, Université de Paris Saclay, Paris, France.</footnote>

<footnote n="4">⁴Institut du Cancer Paris CARPEM, Department of Biology, Hôpital Européen Georges Pompidou, AP-HP, Paris, France.</footnote>

<footnote>* Corresponding Author:</footnote>
<figure><img src="image_2.png" /><figcaption>**FIGURE 1:** A proposed model for EP300 cytoplasm-nucleus shuttling in response to nutrients and in HGPS. Nutrient depletion triggers the relocation of EP300 from the cytoplasm to the nucleus resulting in the inhibition of mTORC1 and subsequent stimulation of autophagy. This is facilitated through AMPK-dependent phosphorylation of EP300 at Serine 89. Nutrients replenishment in starved cells induces PP2A-dependent dephosphorylation of nuclear EP300, facilitating its transportation to cytoplasm by CRM1, thereby promoting mTORC1 reactivation. In HGPS cells, EP300 cytoplasm-nucleus shuttling is altered, causing mTORC1 hyperactivation and impaired autophagy. This is mediated by Progerin-dependent upregulation of CRM1 and alterations in AMPK activity. Interestingly, impaired autophagy leads, in turn, to the accumulation of Progerin, which potentially amplifies the disturbance of the mTORC1/autophagy pathway. The accumulation of Progerin initiates diverse cellular responses linked to accelerated aging. Normalizing HGPS phenotypes can be achieved by modulating EP300 nucleocytoplasmic shuttling. Blue line depicts a nutrient-rich condition, while the red line depicts a nutrient-depleted condition. The grey dotted lines delineate the compromised autophagy process observed in HGPS.</figcaption></figure>

regulated in diseases associated with accelerated aging?

Sung Min Son et al. examined these burning questions by exploring the precise mechanism through which EP300 regulates mTORC1 activity after amino acid or glucose deprivation [6]. They showed that EP300 (rather than other lysine acetyltransferases, KATs), plays a critical role in regulating mTORC1 activity through a mechanism that involves the acetylation of the mTORC1 component RAPTOR. In fact, the depletion of EP300 from cells by RNA interference leads to the impairment of mTORC1 activity accompanied

by diminished RAPTOR acetylation as well as by decreased lysosomal membrane localization of mTORC1. These deficiencies were effectively rescued by the overexpression of functional wild-type (WT) EP300 but not by a dominant-negative (DN) EP300 construct. Depletion of EP300 also resulted in enhanced functional autophagy, corroborating previous studies underscoring the capacity of EP300 to repress autophagy in response to several stimuli including nutrient starvation, spermidine and curcumin [11, 12]. Conversely, pro-autophagic stimuli either by depletion of
<figure><img src="image_2.png" /><figcaption>**FIGURE 1:** A proposed model for EP300 cytoplasm-nucleus shuttling in response to nutrients and in HGPS. Nutrient depletion triggers the relocation of EP300 from the cytoplasm to the nucleus resulting in the inhibition of mTORC1 and subsequent stimulation of autophagy. This is facilitated through AMPK-dependent phosphorylation of EP300 at Serine 89. Nutrients replenishment in starved cells induces PP2A-dependent dephosphorylation of nuclear EP300, facilitating its transportation to cytoplasm by CRM1, thereby promoting mTORC1 reactivation. In HGPS cells, EP300 cytoplasm-nucleus shuttling is altered, causing mTORC1 hyperactivation and impaired autophagy. This is mediated by Progerin-dependent upregulation of CRM1 and alterations in AMPK activity. Interestingly, impaired autophagy leads, in turn, to the accumulation of Progerin, which potentially amplifies the disturbance of the mTORC1/autophagy pathway. The accumulation of Progerin initiates diverse cellular responses linked to accelerated aging. Normalizing HGPS phenotypes can be achieved by modulating EP300 nucleocytoplasmic shuttling. Blue line depicts a nutrient-rich condition, while the red line depicts a nutrient-depleted condition. The grey dotted lines delineate the compromised autophagy process observed in HGPS.</figcaption></figure>

regulated in diseases associated with accelerated aging?

Sung Min Son et al. examined these burning questions by exploring the precise mechanism through which EP300 regulates mTORC1 activity after amino acid or glucose deprivation [6]. They showed that EP300 (rather than other lysine acetyltransferases, KATs), plays a critical role in regulating mTORC1 activity through a mechanism that involves the acetylation of the mTORC1 component RAPTOR. In fact, the depletion of EP300 from cells by RNA interference leads to the impairment of mTORC1 activity accompanied

by diminished RAPTOR acetylation as well as by decreased lysosomal membrane localization of mTORC1. These deficiencies were effectively rescued by the overexpression of functional wild-type (WT) EP300 but not by a dominant-negative (DN) EP300 construct. Depletion of EP300 also resulted in enhanced functional autophagy, corroborating previous studies underscoring the capacity of EP300 to repress autophagy in response to several stimuli including nutrient starvation, spermidine and curcumin [11, 12]. Conversely, pro-autophagic stimuli either by depletion of
cytosolic acetyl coenzyme A (CoA), the donor of acetyl groups transferred onto EP300 substrates, or by direct inhibition of the catalytic activity of EP300, reduced EP300 activity [11, 13].

A large body of evidence supports the involvement of EP300 in the negative regulation of autophagy through the acetylation of various ATG proteins, each playing distinct roles in various steps of the autophagic cascade [14]. However, Sung Min Son et al. reported that upon depletion of amino acids, the dominant process resulting in autophagy stimulation involves reduced RAPTOR acetylation leading to mTORC1 inhibition rather than deacetylation of other autophagy regulators [6]. Several questions arise from these findings: How does the localization of EP300 affect the accessibility of EP300 to its diverse substrates? Does EP300-mediated RAPTOR acetylation serve as a universal mechanism for the regulation of autophagy?

More importantly, Sung Min Son et al. demonstrated that the cytoplasm-to-nuclear transport of EP300 plays as a central role in regulating mTORC1 in response to nutrient status. The authors showed that EP300 nuclear transport occurs in diverse cell lines exposed to amino acid or glucose deprivation, accompanied by diminished EP300 cytoplasmic activity and reduced interaction between EP300 and RAPTOR [6]. Moreover, the reduction in RAPTOR acetylation and mTORC1 activity in cells expressing a constitutively cytoplasmic form of EP300 construct was less prominent after amino acid or glucose depletion as compared to WT EP300. Similarly, the brains of starved mice, which exhibit decreased RAPTOR acetylation and mTORC1 activity, also contain more nuclear and less cytoplasmic EP300 [6]. Altogether, these findings suggest that the nucleocytoplasmic shuttling of EP300 plays a pivotal role in the regulation mTORC1 activity in response to nutrient status both in vitro and in vivo.

Moreover, using an acetylation-refractory mutant of RAPTOR in which a critical lysine residue that usually is acetylated by EP300 was replaced by arginine (KR; K1097R). Sung Min Son et al. showed that cytoplasmic EP300 represses autophagy through a mechanism that depends on RAPTOR acetylation. The impact of EP300 cellular localization on autophagy regulation has also been reported by Sebti et al., who demonstrated that during starvation, BCL2-associated athanogene 6 (BAT6), binds to EP300 and facilitates its transport to the nucleus [15]. When BAT6 is absent, EP300 nuclear shuttling is inhibited in starved cells, leading to cytoplasmic ATG7 hyperacetylation and subsequently autophagy inhibition. It might be interesting to investigate the precise molecular mechanism through which BAT6 regulates EP300 shuttling and determine its regulation of mTORC1 activity.

Sung Min Son et al. investigated how EP300 shuttling is regulated by nutrient status (Fig. 1). Among specific inhibitors of major kinases, they showed that only an AMP-activated protein kinase (AMPK) inhibitor could suppress the nuclear transport of EP300 after amino acid depletion. Mechanistically, during amino acid starvation, AMPK phosphorylates EP300 at serine 89, thereby facilitating its nu-

clear translocation and its trapping by 14-3-3ζ in the nucleus, then leading to decreased RAPTOR acetylation and subsequent inhibition of mTORC1 activity. Conversely, the addition of amino acids to starved cells leads to the dephosphorylation of EP300 by phosphatase 2A (PP2A). This event facilitates the nuclear export of EP300 to the cytoplasm through a mechanism involving the chromosomal maintenance 1 (CRM1), also known as exportin 1.

The Hutchinson-Gilford progeria syndrome (HGPS) is a rare sporadic autosomal dominant disorder characterized by accelerated aging [16]. Earlier studies have demonstrated mTORC1 hyperactivity in HGPS, and inhibition of mTORC1 effectively diminishes characteristic HGPS phenotypes, such as defects in nuclear morphology (with deformation of the envelope) and accumulation of Progerin (the disease-causing protein), suggesting a causal role for mTORC1 overactivation in HGPS [17, 18].

Sung Min Son et al. investigated possible alterations of EP300 cytoplasm-nuclear shuttling in HGPS patient-derived fibroblasts. By employing doxycycline-inducible Progerin-expressing cell lines, the authors showed that Progerin expression led to a reduction of EP300 nuclear transport causing mTORC1 activation and subsequently autophagy inhibition. In addition, EP300 nuclear translocation and mTORC1 activity were compromised in fibroblasts derived from HGPS patients after amino acid starvation. Moreover, HGPS fibroblasts failed to activate AMPK following starvation and exhibited increased CRM1 expression [6]. These findings corroborate prior findings indicating an enhanced nuclear protein export pathway in HGPS that is linked to progerin-mediated CRM1 upregulation [19].

Altogether, the results suggest that the overactivation of mTORC1 in HGPS is linked to the alteration of EP300 cytoplasm-nuclear shuttling driven by Progerin (Fig. 1). This may be ascribed to CRM1 upregulation and/or alteration in AMPK activity, or potentially involve other yet-to-be-defined mechanisms. Interestingly, the degradation of Progerin through autophagy is compromised in HGPS, suggesting the existence of a vicious cycle in which the elevation of Progerin inhibits autophagy and compromised autophagy then reduces the capacity of cells to keep Progerin levels low. The abnormal accumulation of Progerin in HGPS can be corrected by inhibitors of EP300 or CRM1 or activators of AMPK. Similarly, rapamycin, an inhibitor of mTORC1 and inducer of autophagy, has the capacity to normalize the characteristic HGPS phenotypes [17, 18]. In another study, spermidine, an inhibitor of EP300 that stimulates autophagy, has demonstrated the capability to significantly extend the lifespan of yeast, flies and worms, and human immune cells [12]. Other caloric restriction mimetics (compounds that trigger the protective mechanisms associated with caloric restriction) have also been shown to promote autophagy and reverse aging-derived effects through a reduction of protein acetylation [20].

In conclusion, the work of Sung Min Son et al. advances our understanding of how the nucleocytoplasmic shuttling of EP300 affects the mTORC1/autophagy axis in response to nutrient status and in Hutchinson-Gilford progeria syn-
cytosolic acetyl coenzyme A (CoA), the donor of acetyl groups transferred onto EP300 substrates, or by direct inhibition of the catalytic activity of EP300, reduced EP300 activity [11, 13].

A large body of evidence supports the involvement of EP300 in the negative regulation of autophagy through the acetylation of various ATG proteins, each playing distinct roles in various steps of the autophagic cascade [14]. However, Sung Min Son et al. reported that upon depletion of amino acids, the dominant process resulting in autophagy stimulation involves reduced RAPTOR acetylation leading to mTORC1 inhibition rather than deacetylation of other autophagy regulators [6]. Several questions arise from these findings: How does the localization of EP300 affect the accessibility of EP300 to its diverse substrates? Does EP300-mediated RAPTOR acetylation serve as a universal mechanism for the regulation of autophagy?

More importantly, Sung Min Son et al. demonstrated that the cytoplasm-to-nuclear transport of EP300 plays as a central role in regulating mTORC1 in response to nutrient status. The authors showed that EP300 nuclear transport occurs in diverse cell lines exposed to amino acid or glucose deprivation, accompanied by diminished EP300 cytoplasmic activity and reduced interaction between EP300 and RAPTOR [6]. Moreover, the reduction in RAPTOR acetylation and mTORC1 activity in cells expressing a constitutively cytoplasmic form of EP300 construct was less prominent after amino acid or glucose depletion as compared to WT EP300. Similarly, the brains of starved mice, which exhibit decreased RAPTOR acetylation and mTORC1 activity, also contain more nuclear and less cytoplasmic EP300 [6]. Altogether, these findings suggest that the nucleocytoplasmic shuttling of EP300 plays a pivotal role in the regulation mTORC1 activity in response to nutrient status both in vitro and in vivo.

Moreover, using an acetylation-refractory mutant of RAPTOR in which a critical lysine residue that usually is acetylated by EP300 was replaced by arginine (KR; K1097R). Sung Min Son et al. showed that cytoplasmic EP300 represses autophagy through a mechanism that depends on RAPTOR acetylation. The impact of EP300 cellular localization on autophagy regulation has also been reported by Sebti et al., who demonstrated that during starvation, BCL2-associated athanogene 6 (BAT6), binds to EP300 and facilitates its transport to the nucleus [15]. When BAT6 is absent, EP300 nuclear shuttling is inhibited in starved cells, leading to cytoplasmic ATG7 hyperacetylation and subsequently autophagy inhibition. It might be interesting to investigate the precise molecular mechanism through which BAT6 regulates EP300 shuttling and determine its regulation of mTORC1 activity.

Sung Min Son et al. investigated how EP300 shuttling is regulated by nutrient status (Fig. 1). Among specific inhibitors of major kinases, they showed that only an AMP-activated protein kinase (AMPK) inhibitor could suppress the nuclear transport of EP300 after amino acid depletion. Mechanistically, during amino acid starvation, AMPK phosphorylates EP300 at serine 89, thereby facilitating its nu-

clear translocation and its trapping by 14-3-3ζ in the nucleus, then leading to decreased RAPTOR acetylation and subsequent inhibition of mTORC1 activity. Conversely, the addition of amino acids to starved cells leads to the dephosphorylation of EP300 by phosphatase 2A (PP2A). This event facilitates the nuclear export of EP300 to the cytoplasm through a mechanism involving the chromosomal maintenance 1 (CRM1), also known as exportin 1.

The Hutchinson-Gilford progeria syndrome (HGPS) is a rare sporadic autosomal dominant disorder characterized by accelerated aging [16]. Earlier studies have demonstrated mTORC1 hyperactivity in HGPS, and inhibition of mTORC1 effectively diminishes characteristic HGPS phenotypes, such as defects in nuclear morphology (with deformation of the envelope) and accumulation of Progerin (the disease-causing protein), suggesting a causal role for mTORC1 overactivation in HGPS [17, 18].

Sung Min Son et al. investigated possible alterations of EP300 cytoplasm-nuclear shuttling in HGPS patient-derived fibroblasts. By employing doxycycline-inducible Progerin-expressing cell lines, the authors showed that Progerin expression led to a reduction of EP300 nuclear transport causing mTORC1 activation and subsequently autophagy inhibition. In addition, EP300 nuclear translocation and mTORC1 activity were compromised in fibroblasts derived from HGPS patients after amino acid starvation. Moreover, HGPS fibroblasts failed to activate AMPK following starvation and exhibited increased CRM1 expression [6]. These findings corroborate prior findings indicating an enhanced nuclear protein export pathway in HGPS that is linked to progerin-mediated CRM1 upregulation [19].

Altogether, the results suggest that the overactivation of mTORC1 in HGPS is linked to the alteration of EP300 cytoplasm-nuclear shuttling driven by Progerin (Fig. 1). This may be ascribed to CRM1 upregulation and/or alteration in AMPK activity, or potentially involve other yet-to-be-defined mechanisms. Interestingly, the degradation of Progerin through autophagy is compromised in HGPS, suggesting the existence of a vicious cycle in which the elevation of Progerin inhibits autophagy and compromised autophagy then reduces the capacity of cells to keep Progerin levels low. The abnormal accumulation of Progerin in HGPS can be corrected by inhibitors of EP300 or CRM1 or activators of AMPK. Similarly, rapamycin, an inhibitor of mTORC1 and inducer of autophagy, has the capacity to normalize the characteristic HGPS phenotypes [17, 18]. In another study, spermidine, an inhibitor of EP300 that stimulates autophagy, has demonstrated the capability to significantly extend the lifespan of yeast, flies and worms, and human immune cells [12]. Other caloric restriction mimetics (compounds that trigger the protective mechanisms associated with caloric restriction) have also been shown to promote autophagy and reverse aging-derived effects through a reduction of protein acetylation [20].

In conclusion, the work of Sung Min Son et al. advances our understanding of how the nucleocytoplasmic shuttling of EP300 affects the mTORC1/autophagy axis in response to nutrient status and in Hutchinson-Gilford progeria syn-
drome. The authors propose a rationale for targeting
EP300 and its regulatory nucleocytoplasmic shuttling
mechanisms. Based on this work, direct or indirect EP300
inhibitors may be considered as promising therapeutic
targets for the treatment of HGPS. The development of
next-generation EP300 inhibitors might also be useful for
the prevention or treatment of other progeroid syndromes
and age-associated diseases as well as for "normal" aging.

ACKNOWLEDGMENTS

LF is supported by a doctoral fellowship from the Ecole
Doctorale Paris-Saclay. GK is supported by the Ligue contre
le Cancer (équipe labellisée); Agence National de la Re-
cherche (ANR) - Projets blancs; AMMICa US23/CNRS
UMS3655; Association pour la recherche sur le cancer
(ARC); Cancéropôle Ile-de-France; Fondation pour la Re-
cherche Médicale (FRM); a donation by Elior; Equipex On-
co-Pheno-Screen; European Joint Programme on Rare Dis-
eases (EJPRD) Wilsonmed; European Research Council Ad-
vanced Investigator Award (ERC-2021-ADG, Grant No.
101052444; project acronym: ICD-Cancer, project title:
Immunogenic cell death (ICD) in the cancer-immune dia-
logue), The ERA4 Health Cardinoff Grant Ener-LIGHT, Euro-
pean Union Horizon 2020 research and innovation pro-
gramme Oncobiome (grant agreement number: 825410,
Project Acronym: ONCOBIOME, Project title: Gut OncoMi-
crobiome Signatures [GOMS] associated with cancer inci-
dence, prognosis and prediction of treatment response,
Prevalung (grant agreement number 101095604, Project
Acronym: PREVALUNG EU, project title: Biomarkers affect-
ing the transition from cardiovascular disease to lung can-
cer: towards stratified interception), Crimson (grant
agreement number: 101016923; Project Acronym: CRIM-
SON, Project title: Coherent Raman Imaging for the Molec-
ular Study of the OrigiN of diseases); Neutrocure (grant
agreement number 861878 : Project Acronym: Neutro-
cure ; project title: Development of "smart" amplifiers of
reactive oxygen species specific to aberrant polymorpho-
nuclear neutrophils for treatment of inflammatory and
autoimmune diseases, cancer and myeloablation); Hevolu-
tion Network on Senescence in Aging; Institut National du
Cancer (INCa); Institut Universitaire de France; LabEx Im-
muno-Oncology ANR-18-IDEX-0001; a Cancer Research
ASPIRE Award from the Mark Foundation; PAIR-Obésité
INCa_1873, the RHUs Immunolife and LUCA-pi (both dedi-
cated to France Relance 2030); Seerave Foundation; SIRIC
Stratified Oncology Cell DNA Repair and Tumor Immune
Elimination (SOCRATE); and SIRIC Cancer Research and

Personalized Medicine (CARPEM). This study contributes to the IdEx Université de Paris Cité ANR-18-IDEX-0001. Views and opinions expressed are those of the author(s) only and do not necessarily reflect those of the European Union, the European Research Council or any other granting authority. Neither the European Union nor any other granting authority can be held responsible for them. M.D-M is supported by funds from the Institut National de la Santé et de la Recherche Médicale (INSERM) and grants from the Agence National de la Recherche (ANR-21-CE44-0016 (CISCO), ANR-23-CE13-0013-0 (JANUS), INCa (PLBIO23-216) and Taxe d'apprentissage IGR KAAL-2022.

CONFLICT OF INTEREST

GK has been holding research contracts with Daiichi Sankyo, Eleor, Kaleido, Lytix Pharma, PharmaMar, Osasuna Therapeutics, Samsara Therapeutics, Sanofi, Tollys, and Vascage. GK is on the Board of Directors of the Bristol Myers Squibb Foundation France. GK is a scientific co-founder of everImmune, Osasuna Therapeutics, Samsara Therapeutics and Therafast Bio. GK is in the scientific advisory boards of Hevolution, Institut Servier, Longevity Vision Funds and Rejuveron Life Sciences. GK is the inventor of patents covering therapeutic targeting of aging, cancer, cystic fibrosis and metabolic disorders. GK's wife, Laurence Zitvogel, has held research contracts with Glaxo Smyth Kline, Incyte, Lytix, Kaleido, Innovate Pharma, Daiichi Sankyo, Pilege, Merus, Transgene, 9 m, Tusk and Roche, was on the on the Board of Directors of Transgene, is a cofounder of everImmune, and holds patents covering the treatment of cancer and the therapeutic manipulation of the microbiota. GK's brother, Romano Kroemer, was an employee of Sanofi and now consults for Boehringer-Ingelheim. The funders had no role in the design of the study; in the writing of the manuscript, or in the decision to publish the results.

COPYRIGHT

© 2024 Ferret et al. This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduction in any medium, provided the original author and source are acknowledged.

Please cite this article as: Lucille Ferret, Guido Kroemer and
Mojgan Djavaheri-Mergny (2024). Pathogenic hyperactivation of
mTORC1 by cytoplasmic EP300 in Hutchinson-Gilford progeria
syndrome. *Cell Stress* 8: 51-55. doi: 10.15698/cst2024.04.295
drome. The authors propose a rationale for targeting EP300 and its regulatory nucleocytoplasmic shuttling mechanisms. Based on this work, direct or indirect EP300 inhibitors may be considered as promising therapeutic targets for the treatment of HGPS. The development of next-generation EP300 inhibitors might also be useful for the prevention or treatment of other progeroid syndromes and age-associated diseases as well as for "normal" aging.

## ACKNOWLEDGMENTS

LF is supported by a doctoral fellowship from the Ecole Doctorale Paris-Saclay. GK is supported by the Ligue contre le Cancer (équipe labellisée); Agence National de la Recherche (ANR) - Projets blancs; AMMICa US23/CNRS UMS3655; Association pour la recherche sur le cancer (ARC); Cancéropôle Ile-de-France; Fondation pour la Recherche Médicale (FRM); a donation by Elior; Equipex Onco-Pheno-Screen; European Joint Programme on Rare Diseases (EJPRD) Wilsonmed; European Research Council Advanced Investigator Award (ERC-2021-ADG, Grant No. 101052444; project acronym: ICD-Cancer, project title: Immunogenic cell death (ICD) in the cancer-immune dialogue), The ERA4 Health Cardinoff Grant Ener-LIGHT, European Union Horizon 2020 research and innovation programme Oncobiome (grant agreement number: 825410, Project Acronym: ONCOBIOME, Project title: Gut OncoMicrobiome Signatures [GOMS] associated with cancer incidence, prognosis and prediction of treatment response, Prevalung (grant agreement number 101095604, Project Acronym: PREVALUNG EU, project title: Biomarkers affecting the transition from cardiovascular disease to lung cancer: towards stratified interception), Crimson (grant agreement number: 101016923; Project Acronym: CRIMSON, Project title: Coherent Raman Imaging for the Molecular Study of the OrigIN of diseases); Neutrocure (grant agreement number 861878 : Project Acronym: Neutrocure ; project title: Development of "smart" amplifiers of reactive oxygen species specific to aberrant polymorphonuclear neutrophils for treatment of inflammatory and autoimmune diseases, cancer and myeloablation); Hevolution Network on Senescence in Aging; Institut National du Cancer (INCa); Institut Universitaire de France; LabEx Immuno-Oncology ANR-18-IDEX-0001; a Cancer Research ASPIRE Award from the Mark Foundation; PAIR-Obésité INCa_1873, the RHUs Immunolife and LUCA-pi (both dedicated to France Relance 2030); Seerave Foundation; SIRIC Stratified Oncology Cell DNA Repair and Tumor Immune Elimination (SOCRATE); and SIRIC Cancer Research and

Personalized Medicine (CARPEM). This study contributes to the IdEx Université de Paris Cité ANR-18-IDEX-0001. Views and opinions expressed are those of the author(s) only and do not necessarily reflect those of the European Union, the European Research Council or any other granting authority. Neither the European Union nor any other granting authority can be held responsible for them. M.D-M is supported by funds from the Institut National de la Santé et de la Recherche Médicale (INSERM) and grants from the Agence National de la Recherche (ANR-21-CE44-0016 (CISCO), ANR-23-CE13-0013-0 (JANUS), INCa (PLBIO23-216) and Taxe d'apprentissage IGR KAAL-2022.

## CONFLICT OF INTEREST

GK has been holding research contracts with Daiichi Sankyo, Eleor, Kaleido, Lytix Pharma, PharmaMar, Osasuna Therapeutics, Samsara Therapeutics, Sanofi, Tollys, and Vascage. GK is on the Board of Directors of the Bristol Myers Squibb Foundation France. GK is a scientific co-founder of everImmune, Osasuna Therapeutics, Samsara Therapeutics and Therafast Bio. GK is in the scientific advisory boards of Hevolution, Institut Servier, Longevity Vision Funds and Rejuveron Life Sciences. GK is the inventor of patents covering therapeutic targeting of aging, cancer, cystic fibrosis and metabolic disorders. GK's wife, Laurence Zitvogel, has held research contracts with Glaxo Smyth Kline, Incyte, Lytix, Kaleido, Innovate Pharma, Daiichi Sankyo, Pilege, Merus, Transgene, 9 m, Tusk and Roche, was on the Board of Directors of Transgene, is a cofounder of everImmune, and holds patents covering the treatment of cancer and the therapeutic manipulation of the microbiota. GK's brother, Romano Kroemer, was an employee of Sanofi and now consults for Boehringer-Ingelheim. The funders had no role in the design of the study; in the writing of the manuscript, or in the decision to publish the results.

## COPYRIGHT

© 2024 Ferret et al. This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduction in any medium, provided the original author and source are acknowledged.

Please cite this article as: Lucille Ferret, Guido Kroemer and Mojgan Djavaheri-Mergny (2024). Pathogenic hyperactivation of mTORC1 by cytoplasmic EP300 in Hutchinson-Gilford progeria syndrome. Cell Stress 8: 51-55. doi: 10.15698/cst2024.04.295
REFERENCES

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2. Panwar V, Singh A, Bhatt M, Tonk RK, Azizov S, Raza AS, Sengupta S, Kumar D, and Garg M (2023). Multifaceted role of mTOR (mammalian target of rapamycin) signaling pathway in human health and disease. *Signal Transduct Target Ther.* 8(1): 375. doi: 10.1038/s41392-023-01608-z

3. Rubinsztein DC, Mariño G, and Kroemer G (2011). Autophagy and aging. *Cell*. 146(5): 682–695. doi: 10.1016/j.cell.2011.07.030

4. Papadopoli D, Boulay K, Kazak L, Pollak M, Mallette FA, Topisirovic I, and Hulea L (2019). mTOR as a central regulator of lifespan and aging. *F1000Research*. 8: F1000 Faculty Rev-998. doi: 10.12688/f1000research.17196.1

5. López-Otín C, Blasco MA, Partridge L, Serrano M, and Kroemer G (2023). Hallmarks of aging: An expanding universe. *Cell*. 186(2): 243–278. doi: 10.1016/j.cell.2022.11.001

6. Son SM, Park SJ, Breusegem SY, Larrieu D, Rubinsztein DC (2024). EP300 nucleocytoplasmic shuttling underlies mTORC1 hyperactivation in Hutchinson-Gilford progeria syndrome. *Nat Cell Biol.* 26(2):235-249. doi: 10.1038/s41556-023-01338-y

7. Son SM, Park SJ, Stamatakou E, Vicinanza M, Menzies FM, and Rubinsztein DC (2020). Leucine regulates autophagy via acetylation of the mTORC1 component raptor. *Nat Commun.* 11(1): 3148. doi: 10.1038/s41467-020-16886-2

8. Gwinn DM, Shackelford DB, Egan DF, Mihaylova MM, Mery A, Vasquez DS, Turk BE, and Shaw RJ (2008). AMPK phosphorylation of raptor mediates a metabolic checkpoint. *Mol Cell.* 30(2): 214–226. doi: 10.1016/j.molcel.2008.03.003

9. Lacher MD, Pincheira RJ, and Castro AF (2011). Consequences of interrupted Rheb-to-AMPK feedback signaling in tuberous sclerosis complex and cancer. *Small GTPases*. 2(4): 211–216. doi: 10.4161/sgtp.2.4.16703

10. Kim J, Kundu M, Viollet B, and Guan K-L (2011). AMPK and mTOR regulate autophagy through direct phosphorylation of Ulk1. *Nat Cell Biol.* 13(2): 132–141. doi: 10.1038/ncb2152

11. Mariño G et al. (2014). Regulation of autophagy by cytosolic acetyl-coenzyme A. *Mol Cell.* 53(5): 710–725. doi: 10.1016/j.molcel.2014.01.016

12. Pietrocola F, Lachkar S, Enot DP, Niso-Santano M, Bravo-San Pedro JM, Sica V, Izzo V, Maiuri MC, Madeo F, Mariño G, and Kroemer G (2015). Spermidine induces autophagy by inhibiting the acetyltransferase EP300. *Cell Death Differ.* 22(3): 509–516. doi: 10.1038/cdd.2014.215

13. Son SM, Park SJ, Lee H, Siddiqi F, Lee JE, Menzies FM, and Rubinsztein DC (2019). Leucine Signals to mTORC1 via Its Metabolite Acetyl-Coenzyme A. *Cell Metab.* 29(1): 192-201.e7. doi: 10.1016/j.cmet.2018.08.013

14. Xu Y, and Wan W (2023). Acetylation in the regulation of autophagy. *Autophagy*. 19(2): 379–387. doi: 10.1080/15548627.2022.2062112

15. Sebti S, Prébois C, Pérez-Gracia E, Bauvy C, Desmots F, Pirot N, Gongora C, Bach A-S, Hubberstey AV, Palissot V, Berchem G, Codogno P, Linares LK, Liaudet-Coopman E, and Pattingre S (2014). BAT3 modulates EP300-dependent acetylation of p53 and autophagy-related protein 7 (ATG7) during autophagy. *Proc Natl Acad Sci U S A.* 111(11): 4115–4120. doi: 10.1073/pnas.1313618111

16. Cisneros B, García-Aguirre I, De Ita M, Arrieta-Cruz I, and Rosas-Vargas H (2023). Hutchinson-Gilford Progeria Syndrome: Cellular Mechanisms and Therapeutic Perspectives. *Arch Med Res.* 54(5): 102837. doi: 10.1016/j.arcmed.2023.06.002

17. Cao K, Graziotto JJ, Blair CD, Mazzulli JR, Erdos MR, Krainc D, and Collins FS (2011). Rapamycin reverses cellular phenotypes and enhances mutant protein clearance in Hutchinson-Gilford progeria syndrome cells. *Sci Transl Med.* 3(89): 89ra58. doi: 10.1126/scitranslmed.3002346

18. Graziotto JJ, Cao K, Collins FS, and Krainc D (2012). Rapamycin activates autophagy in Hutchinson-Gilford progeria syndrome: implications for normal aging and age-dependent neurodegenerative disorders. *Autophagy*. 8(1): 147–151. doi: 10.4161/auto.8.1.18331

19. García-Aguirre I, Alamillo-Iniesta A, Rodríguez-Pérez R, Vélez-Aguilera G, Amaro-Encarnación E, Jiménez-Gutiérrez E, Vásquez-Limeta A, Samuel Laredo-Cisneros M, Morales-Lázaro SL, Tiburcio-Félix R, Ortega A, Magaña JJ, Winder SJ, and Cisneros B (2019). Enhanced nuclear protein export in premature aging and rescue of the progeria phenotype by modulation of CRM1 activity. *Aging Cell.* 18(5): e13002. doi: 10.1111/acel.13002

20. Madeo F, Carmona-Gutierrez D, Hofer SJ, and Kroemer G (2019). Caloric Restriction Mimetics against Age-Associated Disease: Targets, Mechanisms, and Therapeutic Potential. *Cell Metab.* 29(3): 592–610. doi: 10.1016/j.cmet.2019.01.018
REFERENCES

1. Laplante M, and Sabatini DM (2009). mTOR signaling at a glance. *J Cell Sci.* 122(Pt 20): 3589–3594. doi: 10.1242/jcs.051011

2. Panwar V, Singh A, Bhatt M, Tonk RK, Azizov S, Raza AS, Sengupta S, Kumar D, and Garg M (2023). Multifaceted role of mTOR (mammalian target of rapamycin) signaling pathway in human health and disease. *Signal Transduct Target Ther.* 8(1): 375. doi: 10.1038/s41392-023-01608-z

3. Rubinsztein DC, Mariño G, and Kroemer G (2011). Autophagy and aging. *Cell*. 146(5): 682–695. doi: 10.1016/j.cell.2011.07.030

4. Papadopoli D, Boulay K, Kazak L, Pollak M, Mallette FA, Topisirovic I, and Hulea L (2019). mTOR as a central regulator of lifespan and aging. *F1000Research*. 8: F1000 Faculty Rev-998. doi: 10.12688/f1000research.17196.1

5. López-Otín C, Blasco MA, Partridge L, Serrano M, and Kroemer G (2023). Hallmarks of aging: An expanding universe. *Cell*. 186(2): 243–278. doi: 10.1016/j.cell.2022.11.001

6. Son SM, Park SJ, Breusegem SY, Larrieu D, Rubinsztein DC (2024). EP300 nucleocytoplasmic shuttling underlies mTORC1 hyperactivation in Hutchinson-Gilford progeria syndrome. *Nat Cell Biol.* 26(2):235-249. doi: 10.1038/s41556-023-01338-y

7. Son SM, Park SJ, Stamatakou E, Vicinanza M, Menzies FM, and Rubinsztein DC (2020). Leucine regulates autophagy via acetylation of the mTORC1 component raptor. *Nat Commun.* 11(1): 3148. doi: 10.1038/s41467-020-16886-2

8. Gwinn DM, Shackelford DB, Egan DF, Mihaylova MM, Mery A, Vasquez DS, Turk BE, and Shaw RJ (2008). AMPK phosphorylation of raptor mediates a metabolic checkpoint. *Mol Cell.* 30(2): 214–226. doi: 10.1016/j.molcel.2008.03.003

9. Lacher MD, Pincheira RJ, and Castro AF (2011). Consequences of interrupted Rheb-to-AMPK feedback signaling in tuberous sclerosis complex and cancer. *Small GTPases*. 2(4): 211–216. doi: 10.4161/sgtp.2.4.16703

10. Kim J, Kundu M, Viollet B, and Guan K-L (2011). AMPK and mTOR regulate autophagy through direct phosphorylation of Ulk1. *Nat Cell Biol.* 13(2): 132–141. doi: 10.1038/ncb2152

11. Mariño G et al. (2014). Regulation of autophagy by cytosolic acetyl-coenzyme A. **Mol Cell.** 53(5): 710–725. doi: 10.1016/j.molcel.2014.01.016

12. Pietrocola F, Lachkar S, Enot DP, Niso-Santano M, Bravo-San Pedro JM, Sica V, Izzo V, Maiuri MC, Madeo F, Mariño G, and Kroemer G (2015). Spermidine induces autophagy by inhibiting the acetyltransferase EP300. **Cell Death Differ.** 22(3): 509–516. doi: 10.1038/cdd.2014.215

13. Son SM, Park SJ, Lee H, Siddiqi F, Lee JE, Menzies FM, and Rubinsztein DC (2019). Leucine Signals to mTORC1 via Its Metabolite Acetyl-Coenzyme A. **Cell Metab.** 29(1): 192-201.e7. doi: 10.1016/j.cmet.2018.08.013

14. Xu Y, and Wan W (2023). Acetylation in the regulation of autophagy. *Autophagy*. 19(2): 379–387. doi: 10.1080/15548627.2022.2062112

15. Sebti S, Prébois C, Pérez-Gracia E, Bauvy C, Desmots F, Pirot N, Gongora C, Bach A-S, Hubberstey AV, Palissot V, Berchem G, Codogno P, Linares LK, Liaudet-Coopman E, and Pattingre S (2014). BAT3 modulates EP300-dependent acetylation of p53 and autophagy-related protein 7 (ATG7) during autophagy. *Proc Natl Acad Sci U S A.* 111(11): 4115–4120. doi: 10.1073/pnas.1313618111

16. Cisneros B, García-Aguirre I, De Ita M, Arrieta-Cruz I, and Rosas-Vargas H (2023). Hutchinson-Gilford Progeria Syndrome: Cellular Mechanisms and Therapeutic Perspectives. **Arch Med Res.** 54(5): 102837. doi: 10.1016/j.arcmed.2023.06.002

17. Cao K, Graziotto JJ, Blair CD, Mazzulli JR, Erdos MR, Krainc D, and Collins FS (2011). Rapamycin reverses cellular phenotypes and enhances mutant protein clearance in Hutchinson-Gilford progeria syndrome cells. **Sci Transl Med.** 3(89): 89ra58. doi: 10.1126/scitranslmed.3002346

18. Graziotto JJ, Cao K, Collins FS, and Krainc D (2012). Rapamycin activates autophagy in Hutchinson-Gilford progeria syndrome: implications for normal aging and age-dependent neurodegenerative disorders. *Autophagy*. 8(1): 147–151. doi: 10.4161/auto.8.1.18331

19. García-Aguirre I, Alamillo-Iniesta A, Rodríguez-Pérez R, Vélez-Aguilera G, Amaro-Encarnación E, Jiménez-Gutiérrez E, Vásquez-Limeta A, Samuel Laredo-Cisneros M, Morales-Lázaro SL, Tiburcio-Félix R, Ortega A, Magaña JJ, Winder SJ, and Cisneros B (2019). Enhanced nuclear protein export in premature aging and rescue of the progeria phenotype by modulation of CRM1 activity. **Aging Cell.** 18(5): e13002. doi: 10.1111/acel.13002

20. Madeo F, Carmona-Gutierrez D, Hofer SJ, and Kroemer G (2019). Caloric Restriction Mimetics against Age-Associated Disease: Targets, Mechanisms, and Therapeutic Potential. **Cell Metab.** 29(3): 592–610. doi: 10.1016/j.cmet.2019.01.018