bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ac-SDKP inhibits Tunicamycin-induced ER stress UPR's sensors and subsequently inflammation and fibrosis in human cardiac fibroblasts
Authors: SUHAIL HAMID , Peng Hongmei , Nour-Eddin Rhaleb 
Published: May 2023

Background: Endoplasmic Reticulum (ER) stress, chronic inflammation and cardiac fibrosis are very common pathophysiologic processes found in hypertension and other cardiovascular diseases. Prolonged ER stress disturbs ER functional capacity, resulting from accumulated unfolded or misfolded proteins in ER lumen. Thereby, cells activate an adaptive mechanism ‘unfolded protein response (UPR)’ to restore ER normal function. Consequently, a series of downstream signaling pathways are activated. N-acetyl-seryl-aspartyl-proline (Ac-SDKP) is an endogenous tetrapeptide released from its precursor thymosin-β4 and found in circulation and organs including heart and kidneys. Previously, our in-vivo studies showed that Ac-SDKP inhibits inflammation and fibrosis through the mechanism that remains elusive. Methods and Results: Quiescent human Cardiac Fibroblast (hCFB) cells were treated with tunicamycin (TM; 0.25 μg/mL) in absence or presence of Ac-SDKP (10 nM) and Tauroursodeoxycholic acid (TUDCA; 500 μg/mL). Ac-SDKP inhibited TM-induced expression of ER stress and downstream mediated UPRs sensors IRE1ɑ, XBP1, ATF4 and CHOP encoding molecular chaperons and protein processing enzymes, at the transcriptional and translational levels [ IRE1α; Ctl (1.0 ± 0.39)***, TM (2.99 ± 0.34), Ac-SDKP +TM (1.9 ± 0.10)*** Tudca +TM (2.5 ± 0.20)***. XBP1; Ctl (1.0 ± 0.36)***, TM (8.56 ± 0.77), Ac-SDKP +TM (4.57 ± 0.4)***, Tudca +TM (5.1 ± 0.6)***. ATF4; Ctl (1.0 ± 0.17)***, TM (5.35 ± 0.63), Ac-SDKP +TM (3.0 ± 0.31)**, Tudca +TM (2.9 ± 0.36)**. CHOP; Ctl (1.0 ± 0.17)***, TM (3.1 ± 0.21), Ac-SDKP +TM (1.75 ± 0.24)***, Tudca +TM (2.0 ± 0.18)**]. The inhibition of ER and UPRs sensors subsequently prevented proinflammatory mediator NF-kB activation, cytokine IL-6 and fibrotic Collagen-I (Coll I) expression [ NF-κB; Ctl (1.0 ± 0.10)*, TM (1.6 ± 0.13), Ac-SDKP +TM (1.08 ± 0.11)†, Tudca +TM (1.09 ± 0.14)†. IL-6; Ctl (1.0 ± 0.18)***, TM (6.8 ± 1.4), Ac-SDKP +TM (1.24 ± 0.23***), Tudca +TM (1.3 ± 0.35)***. Coll I; Ctl (1.0 ± 0.02)*** TM (2.5 ± 0.43), Ac-SDKP +TM (1.13 ± 0.13)***, Tudca +TM (1.22 ± 0.18)***]. TM also induced collagen production (Hydroxyproline assay), which was significantly inhibited by Ac-SDKP. The common ER stress inhibitor, TUDCA, exhibited similar inhibitory profile as Ac-SDKP. Conclusion: Ac-SDKP prevents inflammation and fibrosis in hCFB, likely by blocking the overexpressed detrimental ER stress UPRs sensors and its downstream molecular chaperon. Notes: Data are shown a mean ± SEM, p values were calculated using one-way ANOVA compared to CTL. All the experiments are representative of n = 5 – 8.***:p ≤ 0.0001 vs TM; **:p ≤ 0.001 vs TM; *: p ≤ 0.05 vs TM; †:p ≤ 0.05 vs TM. NIH This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
A novel mouse model of systemic hypertension by neprilysin overexpression in myeloid cells
Authors: Hoshi Aoi , Giani Jorge , Bernstein Ellen , Ahmed Faizan , Cao DuoYao , Shibata Tomohiro , Khan Zakir , Saito Suguru , Bernstein Kenneth 
Published: May 2023

There have been many hypertension mouse models created by transgenesis. The transgenesis technologies to create hypertensive mouse models mostly target the renin-angiotensin system (RAS). Here, we show that enhanced expression of neprilysin driven by the myeloid-specific c-fms promoter causes systemic hypertension in mice. [Method] Transgenic mice, termed Nep mice, were created with a construct containing the c-fms promoter and the neprilysin gene (MME). Blood pressure was measured by tail-cuff. Circulating vasoactive substances were analyzed by ELISAs. [Results] Nep mice showed higher systolic blood pressure compared with WT mice (117.0±1.75 vs. 107.1±2.373 mmHg, p=0.0018). The sodium concentration in a 24hr urine was significantly lower in Nep mice (0.2093±0.0039 vs. 0.2445±0.0054 μmol/μl urine, p=0.0004). The concentration of circulating neprilysin was significantly higher in Nep mice (3085±750.5 vs. 1098±197.1 pg/ml, p=0.0283). Notably, the plasma concentration of ANP showed no significant difference between Nep and WT mice although hypertension usually causes an ANP increase. [Conclusion] Overexpression of neprilysin in monocytes causes systemic hypertension associated with sodium and water retention. These mice might be useful for studying the pathologies of heart diseases and hypertension due to volume overload, and in addition, other neprilysin related diseases like Alzheimer’s disease to investigate the interaction with immune cells and beta-amyloid which is cleaved by neprilysin. NIH R01 AI164519 (KEB, P.I.) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
High-resolution respirometry (HRR)-derived assessment of human skeletal muscle respiratory control confirms loss of metabolic flexibility with aging and type 2 diabetes
Authors: Waterman-Vandiver Kayla , Lukasiewicz Cole , Lindsay Keston , Lundby Carsten , Jacobs Robert 
Published: May 2023

Compromised metabolic flexibility is linked to skeletal muscle respiratory control limitations and associated with human senescence and pathological conditions, like type 2 diabetes mellitus (T2D). However, demonstrable proof of compromised metabolic flexibility is limited in research studying aging and T2D, possibly because respiratory control per consensus is commonly assessed at 37°C when mitochondrial temperatures have been shown to reach ~50°C. Therefore, the study objective was to assess indices of skeletal muscle respiratory control and metabolic flexibility via high-resolution respirometry (HRR) in older individuals (OFM) and those diagnosed with T2D. Our hypothesis is that both populations, OFM and T2D, will present with diminished metabolic flexibility when compared to relative controls, young fitness-matched (YFM) or body-mass and BMI-matched middle-aged overweight or obese (MAOO) controls, respectively. Study methodology involved: i) Collecting published HRR-derived assessments of skeletal muscle state 3 respiration using complex I+II substrates obtained with standard experimental conditions at 37°C (OXPHOS37); ii) Temperature correcting published values to reflect mitochondrial temperatures ~10°C higher than contracting muscle (OXPHOS~50); and iii) Estimating metabolic flexibility by taking the difference of OXPHOS37 from OXPHOS~50. Data show that OFM (n = 170; age = 65 ± 6 y; Fitness Percentile = 48 ± 29%) express higher (p < 0.001) rates of OXPHOS37 than YFM (n = 154; age = 25 ± 5 y; Fitness Percentile = 43 ± 14%) with average rates of 123 ± 39 and 109 ± 31 ml/kg/min, respectively, but no observable difference (p = 0.113) between T2D (n=148, body mass = 99 ± 17 kg, BMI = 32 ± 5) and MAOO (n = 267, body mass = 97 ± 19 kg, BMI = 32 ± 6) with average rates of 96 ± 24 and 100 ± 25 ml/kg/min, respectively. Alternatively, temperature correction and determination of metabolic flexibility confirmed our study hypothesis in OFM v YFM (5.88 ± 1.57 and 6.32 ± 1.92 l/min, respectively, p = 0.026) as well as T2D v MAOO (115 ± 29 and 122 ± 31 ml/kg/min, respectively, p = 0.024). A summary of results confirms that OFM and T2D suffer from compromised metabolic flexibility. However, these findings were only observable after temperature correcting previously published HRR-derived data. Conclusions: This study further highlights the importance of maintaining muscle mass and relative fitness, respectively, to retain metabolic flexibility throughout life. Also, general standardized HRR methodologies may currently obscure some biological context and, thus, limit our full application of related research. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Evolutionarily conserved mechanisms regulating hypoxia tolerance in Drosophila melanogaster
Authors: Zhou Dan , Xue Jin , Stobdan Tsering , Haddad Gabriel 
Published: May 2023

Hypoxia is one of the critical pathological elements in many human diseases, including ischemic stroke, myocardial infarction and solid tumors. Understanding the mechanisms regulating hypoxia tolerance or susceptibility is essential for developing effective strategies for medical therapy. In this regard, we generated hypoxia-tolerant Drosophila melanogaster populations through experimental hypoxia-directed evolution in the laboratory, sequenced and analyzed their genomes. In parallel, we took advantage of the natural evolution of humans at high-altitude regions and analyzed the whole genomes of Ethiopian and Andean highlanders. Through a comparative genomic approach, we obtained a group of evolutionarily conserved genes (28 human/23 Drosophila genes) that are potentially involved in regulating hypoxia tolerance in both human highlanders and the hypoxia-tolerant flies. We confirmed that ubiquitous knocking down of the conserved genes, such as grn/ GATA3, inv/ EN1, Mkk4/MAP2K4, Pxt/DUOX1/DUOX2, pyd/TJP1, RapGAP1/RAP1GAP2, Shal/KCN and shep/RBMS3 dramatically enhanced hypoxia tolerance in vivo in Drosophila melanogaster. In addition, we found that glial-specific knocking down of Egfr, grn, pyd and Shal rescued hypoxia-induced lethality. Furthermore, we found that some of these conserved genes (i.e., bnl, croc, Mkk4 and shep) are required by Notch activation-conferred survival in hypoxic environment, whereas Egfr, grn, pyd and Shal regulating hypoxia tolerance through Notch-independent mechanisms. We believe that these evolutionarily conserved mechanisms are novel targets that have a strong potential to be translated into therapeutic strategies to treat or prevent hypoxia-related diseases. This project is supported by NIH grant 1R21NS120023-01A1. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
SLC40A1 is involved in iron accumulation in human lung fibroblasts
Authors: Dang Quanjin , Huang Chaoqun , Liang Yurong , Hewawasam Sankha , Liu Lin 
Published: May 2023

Iron is an essential nutrient for almost all organisms. However, excess iron generates reactive oxygen species and causes tissue injuries. Iron has been shown to accumulate in alveolar macrophages and is implicated in idiopathic pulmonary fibrosis (IPF). In this study, we examined iron accumulation in lung fibroblasts and the underlying mechanisms. We hypothesize that the downregulation of Solute Carrier Family 40 Member 1 ( SLC40A1) results in iron accumulation in lung fibroblasts. Using a Prussian Blue iron staining, we found that iron accumulated in the fibrotic region of the lungs from IPF patients and mice with lung fibrosis induced by bleomycin and asbestos. Iron was partially co-localized with the fibroblast marker vimentin in IPF lungs. By using publicly available scRNA-seq data, we identified SLC40A1, the only known gene involved in iron export, as a down-regulated gene in alveolar fibroblasts. The downregulation of SLC40A1 was confirmed in the lung fibroblasts isolated from IPF patients and bleomycin-treated mice. The treatment of human lung fibroblasts with transforming growth factor-β1 (TGF-β1), a major cytokine elevated in IPF, reduced SLC40A1 mRNA and protein expression. TGF-β1 downregulated SLC40A1 expression via SMAD3 as determined by chromatin immunoprecipitation and luciferase promoter reporter assays. Knockdown of SLC40A1 using lentiviral shRNAs or TGF-β treatment induced iron accumulation in human lung fibroblasts as determined by live cell ferrous dye staining using a SiRhoNox-1 probe. Knockdown of SLC40A1 enhanced the iron-induced lung fibroblast activation. In summary, we conclude that the downregulation of SLC40A1 caused by TGF-β1 induces iron accumulation in lung fibroblasts, resulting in fibroblast activation. R01 HL157450, R01HL135152 and P20GM103648 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Piezo1 and TRPV4 complementary contribute to [Ca2+]i homeostasis in collecting duct cells
Authors: Tomilin Viktor , Stavniichuk Anna , Pyrshev Kyrylo , Kordysh Mariya , Zaika Oleg , Pochynyuk Oleh 
Published: May 2023

Mechanical stress arising from elevated fluid flow is an important regulator of the water-electrolyte transport in the collecting duct (CD). It is well established that mechano-sensitive TRPV4 Ca2+-permeable channel mediates intracellular Ca2+ ([Ca2+]i) responses to high flow in these cells. Piezo1, a Ca2+-permeable channel directly activated by the plasma membrane stretch, is a recent arrival at this scene. Piezo1 expression has been reported in the CD. However, its functional significance is yet to be determined. Here, we applied a combination of Ca2+ imaging and confocal microscopy in freshly isolated split-opened CDs to investigate a potential interplay between TRPV4 and Piezo1 in mediating [Ca2+]i signaling in the CD. Immunofluorescent analysis of split-opened CDs showed presence of Piezo1 in both AQP2-positive (principal cells, PC) and -negative (intercalated cells, IC) with higher intensity in the former. Importantly, Piezo1 was apparent on both apical and basolateral membrane of CD cells. Piezo1 agonists, Yoda-1 (20μM) and Jedi2 (500μM) acutely increase [Ca2+]i in both principal and intercalated cells. The responses were abolished when extracellular Ca2+ was buffered with EGTA suggesting a direct Ca2+ influx via Piezo1. Interestingly, we detected two disparate calcium responses to Piezo1 activation with the majority (70%) cells showing a fast transient response with a sustained plateau, whereas the remaining (30%) population had much slower gradual calcium increase to the same plateau level. Subsequent immunofluorescent analysis revealed that fast Ca2+ responses were attributed to PC, whereas responses with slow kinetics corresponded to IC. Consistently, PCs have ~3 fold higher Piezo-1 signal when compared to neighbor ICs. We next tested whether Piezo1 activity depends on TRPV4 status. Genetic deletion and pharmacological inhibition of TRPV4 with GSK2193874 did not affect Piezo1-dependent elevations in [Ca2+]i. However, high K+ diet, which is known to elevate the flow in the CD and augment both TRPV4 activity and expression, led to diminished Piezo1 responses to Yoda-1. In summary, our results are consistent with the view that Piezo1 and TRPV4 are functional in both principal and intercalated cells of the collecting duct and operate independently to modulate mechanosensitive [Ca2+]i signaling. We hypothesize that augmented TRPV4-dependent [Ca2+]i is compensated by the diminished activity of Piezo1 to account for elevated flow rate upon increased K+ intake. This research was supported by NIH-NIDDK DK117865, DK119170, AHA EIA35260097 (to O. Pochynyuk) and AHA-19CDA34660148 (to V. N. Tomilin). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Does Obesity or Hyperglycemia Alter Metabolic Endotoxemia?
Authors: Bhatwa Arshpreet , Anhê Gabriel , Anhê Fernando , Schertzer Jonathan 
Published: May 2023

Obesity increases the risk of type 2 diabetes and non-alcoholic fatty liver disease, which are two interlinked diseases with a high health and economic burden. Obesogenic diets change the composition of intestinal microbes. Our objective is to move beyond associations of taxonomy and define specific microbial components that alter host immune and metabolic responses. Postbiotics are bacterial components or metabolites derived from living or dead bacteria that can modulate host immunity and metabolism. Lipopolysaccharide (LPS) is a classic example of a postbiotic that acts through toll-like receptor 4 (TLR4) to influence inflammation. Metabolic endotoxemia describes a chronic, low-level increase of LPS seen in blood during metabolic disease. However, it was recently shown that metabolic endotoxemia may be beneficial or detrimental to host metabolism depending on the type of LPS, which is dictated by different species of bacteria. It was previously unknown if obesity or hyperglycemia, is the main driver that alters metabolic endotoxemia. We hypothesized that obesity and hyperglycemia lead to an increase in the inflammatory properties of LPS found in the gut lumen and serum. We tested feces, and the systemic and portal serum obtained from mouse models of hyperglycemia (Akita+/- mice) and obesity ( ob/ob mice) for their TLR4 activation. It was found that hyperglycemia leads to increased fecal TLR4 activation, which can be reduced by lowering blood glucose in Akita+/- mice. In particular, a fed state promotes increased TLR4 activity in the serum of hyperglycemic mice. Elevated levels of TLR4 activity were observed in the serum of ob/ob mice. However, as these mice are transiently hyperglycemic, their elevated levels of blood glucose early on in their life may be a confounding factor leading to increased TLR4 activity. In conclusion, hyperglycemia is a main driver for metabolic endotoxemia and the increased inflammatory properties of LPS in the gut lumen. This research provides a framework of how specific metabolic disease characteristics influence inflammation and will help future studies looking to target the link between hyperglycemia and changes to the specific type of LPS. Canadian Institutes of Health Research, Farncombe Family Digestive Health and Research Institute This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Glutamine Stimulates the Proliferation, Migration, and Survival of Vascular Smooth Muscle Cells
Authors: Durante William , Liu Xiao-ming , Durante Giovanna , Peyton Kelly 
Published: May 2023

Glutamine is an abundant and versatile amino acid that contributes to cellular integrity and function. Glutamine is predominantly metabolized to glutamate and ammonia by the mitochondrial enzyme glutaminase-1 (GLS1). Glutamate is subsequently converted by glutamate dehydrogenase and/or aminotransferases to α-ketoglutarate (α-KG) which feeds into the tricarboxylic acid (TCA) cycle for ATP production and amino acid and lipid synthesis, thereby fulfilling both the energetic and macromolecular requirement of cells. While glutamine is known to regulate the function of vascular smooth muscle cells (SMCs), the metabolic pathways underlying this response are not fully known. Accordingly, the present study investigated the effect of glutamine and its metabolites on vascular SMC function. Incubation of cultured rat or human aortic SMCs with glutamine resulted in a progressive increase in cell proliferation and migration that was accompanied by an increase in cellular glutamate and ammonia levels. Treatment of SMCs with the selective GLS1 inhibitors bis-2-(5-phenylacetoamido-1,3,4,-thiazol-2-yl)ethyl sulfide (BPTES) or CB-839 inhibited the stimulatory effects of glutamine. Flow cytometry experiments revealed that GLS1 inhibitors arrested SMCs in the G0/G1 phase of the cell cycle, and this was associated with a significant decline in DNA synthesis. Glutamine depletion or GLS1 inhibition also sensitized SMCs to the toxic effects of hydrogen peroxide. Interestingly, the administration of cell permeable dimethyl α-KG increased the proliferation and migration of glutamine-deprived SMCs, while the application of ammonia had no effect. In contrast, ammonia, but not dimethyl α-KG, mitigated hydrogen peroxide-mediated death of glutamine-starved SMCs. In conclusion, this study demonstrates that the metabolism of glutamine by GLS1 promotes SMC proliferation, migration, and survival. While the replenishment of the TCA cycle by α-KG contributes to glutamine-dependent growth and motility, the generation of ammonia by GLS1 promotes glutamine-conditional survival. These results identify GLS1 as a promising therapeutic target in treating diseases associated with aberrant vascular SMC phenotypes. This work was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health under Award Number R01 HL149727. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Impaired proteostatic mechanisms other than protein synthesis limit aged skeletal muscle recovery after disuse atrophy
Authors: Fuqua Jordan , Lawrence Marcus , Hettinger Zachary , Borowik Agnieszka , Brecheen Parker , Peelor Frederick , Bodine Sue , Dupont-Versteegden Esther , Miller Benjamin 
Published: May 2023

Older individuals undergo more frequent hospitalizations and periods of bedrest compared to younger persons, causing rapid loss of muscle mass and strength. We and others have shown that old muscle fails to completely regrow following disuse, despite having similar levels of muscle loss during disuse and equal or higher myofibrillar protein synthesis during recovery. Therefore, we hypothesized that a failure of proteostatic mechanisms other than protein synthesis contributes to the inability of old muscle to fully recover after a period of disuse atrophy. Methods: Adult (10 month) and old (30 month) male F344BN rats were hindlimb unloaded for 14 days and then reloaded for up to 60 days. We used a combination of deuterium oxide (D2O) labeling, proteomics, and biochemical analyses to study proteostasis during recovery. Results: There was a failure of old muscle to maintain proteostasis as evident by a greater accumulation of insoluble protein aggregates ( 1.02 ±0.06 vs. 1.22 ±0.06, p<0.05), insoluble collagen ( 4.0 ±1.1 vs. 9.2 ±0.9, p<0.01) and higher amount of advanced glycation end products (AGEs) ( 1.0 ±0.06 vs. 1.5 ±0.08, p<0.001) compared to adult. Old muscle had higher rates of myofibrillar protein synthesis than adult muscle ( 0.029 k/day ±0.002 vs. 0.039 k/day ±0.002, p<0.0001), but also higher rates of breakdown (0.017 1/t ±0.002 vs. 0.028 1/t ±0.004, p<0.05). Differences in the synthesis of collagen were less apparent between adult and old muscle, implying that there was a failure of collagen breakdown in old muscle leading to greater accumulation. Lastly, pathway analysis of proteomic data showed that there were differences in the proteins that accumulated in aggregates between adult and old muscle, and that the synthesis of proteins that regulate proteostasis were different with age. Conclusions: Together, these data indicate that in old muscle altered proteostatic mechanisms other than myofibrillar protein synthesis led to failure to recover from atrophy. Interventions should therefore be targeted at these novel mechanisms instead of protein synthesis alone. NIA Training Grant: 5T32AG052363-04, APS Postdoctoral Fellowship MML, F31AT01147201 ZRH, R01(NCCIH AT009268) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.