bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adipocyte Specific Expression of the PI3 Kinase Regulatory Subunit p85α Causes Reduced Insulin Sensitivity in Mice
Authors: Hetrick Byron , Clayton Zach , Chick Wallace S. , McCurdy Carrie 
Published: June 2021

Obese adipose tissue is characterized by reduced insulin response and elevated, persistent inflammation. Obese adipose tissue has also been shown to have increased abundance of the regulatory subunits of Phosphoinsoitide 3‐kinase (PI3 kinase), p85α, p55α, and p50α. Preventing the upregulation of the PI3 kinase regulatory subunits in response to high fat diet improved insulin response and reduced inflammation in white adipose tissue. p85α contains unique N‐terminal adaptor regions that allows its function outside of regulation of PI3 kinase localization and activity. We therefore hypothesize that p85α upregulation plays a unique role contributing to insulin resistance in obese adipose tissue. To understand how adipocyte specific increases in p85α influence insulin response, we have generated a mouse model overexpressing the PI3 kinase regulatory subunit, p85α, in an adipocyte specific manner. Expression of Cre recombinase is under control of the adiponectin promoter, restricting its expression to white and brown adipocytes. Cre mediated recombination results in overexpression of p85α under control of the constitutive ROSA26 promoter. We observe overexpression of p85α specifically in white adipose tissue. In oral glucose tolerance tests, mice overexpressing p85α show an increased glucose area under the curve. Reduced adipocyte insulin response, or increased inflammation caused by adipocyte p85α overexpression may contribute to the reduced glucose tolerance. We are investigating how adipocyte specific p85α overexpression influences adipose tissue insulin response through modulation of PI3 kinase/Akt signaling pathway in response to insulin. Increased p85α expression may alter PI3 kinase activity, in addition, p85α has been shown to stabilize and activate Phosphatase and tensin homolog (PTEN), which acts in opposition to PI3 kinase to attenuate the PI3K/Akt signal transduction pathway. Besides the direct interactions in the insulin signal transduction cascade, blocking the obesity induced upregulation of PI3 kinase regulatory subunits attenuated the pro‐inflammatory environment of obese adipose tissue. We therefore also predict that p85α overexpression will increase the pro‐inflammatory gene expression profile of adipose tissue through currently unidentified pathways. Based on our observations in an adipocyte specific p85α overexpression mouse line, we propose that high fat diet induced upregulation of p85α is a pathogenic rather than adaptive response to overnutrition. Blocking high fat diet induced upregulation of p85α would likely be an effective strategy to attenuate high fat diet induced insulin resistance.Support or Funding InformationNIH DK095926‐01This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Mitochondrial DNA Damage And Impaired Iron Homeostasis In Muscle Aging
Authors: Picca Anna , Mankowski Robert , Calvani Riccardo , Marzetti Emanuele , Leeuwenburgh Christiaan 
Published: June 2021

Iron dyshomeostasis has been indicated as a major risk factor for the development and progression of several disease conditions. Impairment of iron balance is also an aging feature especially in post‐mitotic tissues. In particular, while age‐related systemic iron deficiency (anemia) compromise oxygen availability, increased cellular and mitochondrial iron levels have been involved in DNA mutation load.We purified total proteins and DNA from muscle samples of young (Y, n=10) and sedentary older adults, classified as high‐ (HFE, n=14) and low‐functioning (LFE, n=6) based on the Short Physical Performance Battery (SPPB). The effect of aging on key proteins involved in iron homeostasis and qualitative alterations of mtDNA and how these relate to physical performance was evaluated.A decrease in muscle volume, as quantified through 3D‐NMR, was found in LFE (38%) and HFE (30%) participants compared to the younger counterpart and positively correlated with physical performance. A lower expression of the iron import protein transferrin receptor (TfR1) but not Zip14 was also found in both groups of elderly participants, regardless of the SPPB score. The analysis of the mutation load of mitochondrial DNA (mtDNA) (e.g., single‐strand, double‐strand breaks and abasic sites), instead, showed an increase in mtDNA damage in HFE and LFE participants, with no differences between the two groups. This study showed an association between altered mitochondrial homeostasis and levels of intracellular iron in aged human muscles. The accumulation of mtDNA mutations and the decline in iron balance may therefore represent critical steps to muscle aging and possible targets for interventions against muscle wasting.Support or Funding InformationThis study was supported by the National Institute on Aging (NIA) (R01 AG17994), the Claude D. Pepper Older Americans Independence Center (1 P30 AG028740), “Centro Studi Achille e Linda Lorenzon”, and Fondazione Roma (NCDs Call for Proposal 2013).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
A Review‐ Structure‐Function studies of Abrin: A ribosome inactivation toxin
Authors: Singh Sarabjit 
Published: June 2021

Abrin is a highly toxic protein produced by Abrus precarious, with an estimated human fatal dose of 0.1–1 μg/kg, and has caused death after accidental and intentional poisoning. Abrin can be extracted from jequirity beans using a relatively simple and cheap procedure. Abrin from the seeds of Abrus precatorius is type II ribosome‐inactivating proteins. Abrin induces apoptosis in cells by triggering intrinsic mitochondrial pathway. The toxins inhibit protein synthesis probably by inactivating the 60S ribosomal subunits, interfering with chain elongation. Only eukaryotic ribosomes are attacked by the toxin. Toxin resistance involves an impairment of the transfer of the toxin A‐chain from the cell surface to the target, the ribosomes. A remarkable group of proteins challenge the notion that protein sequence determines a unique three‐ dimensional structure, and that membrane and soluble proteins are very distinct. Protein synthesis inhibition by abrin and agglutinin‐I in two different cell lines and found that 200–2000 fold higher concentration of agglutinin‐I is needed for the same degree of inhibition. The description of the abrin‐ A chain, APA‐I A chain consists of three folding domains. Domain 1 is composed of residues 2–108 consisting of six stranded β‐sheet, one β‐hairpin and two helices. Domain 2 consists of residues from 109–196 and is the most conserved part of the A chain with total five helices. Domain 3 consists of residues 197–261. It consists of two helices and two anti‐parallel strands. Abrin consists of an A‐chain of 251 amino acids preceded by 34 amino acids followed by a 14 amino acid linker and a B chain of 263 amino acids. There is not more research on abrin in India. Therefore i try to study about toxicity, function and structure of abrin protein.Support or Funding InformationSelf funded.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Developmental Nicotine Exposure Alters Upper Airway Protective Reflexes In Neonates
Authors: Clarke Jordan , Cross Seres , Fregosi Ralph 
Published: June 2021

Although smoking while pregnant is associated with developmental abnormalities in newborns, at least 20% of women smoke during pregnancy. In addition, many women that quit smoking in pregnancy are prescribed nicotine replacement therapies, despite limited knowledge of its developmental consequences on the fetus. Human infants that were smoke‐exposed in utero tend to have more obstructive apneas during sleep than unexposed infants. Here we report the results of experiments designed to examine the impact of developmental nicotine exposure (DNE) on motor output to upper airway muscles in neonatal rats. Pregnant dams were exposed to nicotine (6 mg/kg of nicotine tartrate daily) with an osmotic mini‐pump implanted subdermally on the 5th day of gestation. Neonates (P3‐P10) were lightly anesthetized and placed in a head out body plethysmograph to measure airflow, and fine wires were inserted into the genioglossus muscle to measure the EMG. We examined ventilatory and EMG responses during and after 15‐sec nasal occlusions. The change in EMG burst amplitude in response to nasal occlusion was blunted in DNE animals compared to control, but only in animals younger than P7. DNE animals also show an increased latency period (time of first EMG burst after the onset of nasal occlusion) compared to control animals, again only in animals P7 and younger. Twelve of the 112 animals studied failed to recover following nasal occlusion, and 9 of those 12 were nicotine‐exposed. These results show that nicotine exposure in‐utero does alter upper airway protective reflexes in neonates by increasing the time it takes to respond to respiratory stress and blunting the magnitude of each effort to breathe during their response. Moreover, DNE animals were more likely to die following a nasal occlusion challenge.Support or Funding InformationNIH RO1HD071302This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Endothelin‐1 and COMP Regulate Heme Biosynthesis and Guanylate Cyclase Expression in Smooth Muscle of Pulmonary Arteries
Authors: Alruwaili Norah , Yu Hang , Kelly Melissa R. , Sun Dong , Wolin Michael S. 
Published: June 2021

The objective of this study is to examine if heme biosynthesis is regulated in smooth muscle of pulmonary arteries by endothelin‐1 (ET1) and/or conditions modulating the availability of Cartilage Oligomeric Matrix Protein (COMP). Our recent studies in endothelium‐rubbed bovine pulmonary arteries (BPA) organoid cultured for up to 48 hours observed ET1 (10nM) increases superoxide in the mitochondrial matrix and extra mitochondrial regions associated with COMP depletion. While incubation with COMP (0.5μM) attenuated ET1‐induced superoxide increases. We hypothesize that increased superoxide in the mitochondrial matrix could impair heme biosynthesis from protoporphyrin IX (PpIX) by decreasing the availability of Fe2+ and/or ferrochelatase (FECH). To examine this hypothesis, we studied the effects of ET1, COMP and siRNA depletion of COMP on the expression of FECH, transferrin receptor‐1 (TfR1, an indicator of iron availability) and soluble guanylate cyclase (sGC, a key heme‐dependent protein), and on measurements of PpIX (HPLC) and heme content. ET1 decreased FECH, heme and sGC, and increased PpIX and TfR1. COMP reversed these effects of ET1, and COMP also decreased PpIX and increased heme in the absence of ET1. The depletion of COMP by siRNA increased detection of mitochondrial Matrix (MitoSOX‐HPLC) and extramitochondrial (DHE‐HPLC) superoxide, PpIX and TfR1 expression, and decreased the expression of FECH, sGC and the phosphorylation of VASP on the site mediated by cGMP protein kinase. In vascular reactivity studies, it was observed that relaxation of BPA to the nitric oxide donor spermine NONOate was inhibited by organoid culture with ET1, and this effect of ET1 was attenuated in the presence of COMP during the exposure to ET1. Collectively, ET1 and COMP depletion appears to impair the biosynthesis of heme in pulmonary arteries potentially associated with the loss of protective sGC and cGMP vasodilator and remodeling‐inhibitory mechanisms.Support or Funding InformationSupported by NIH Grants HL115124 & HL129797; The Natural Science Foundation of the P. R. China (31400989); The Natural Science Foundation of Heilongjiang Province (C2015069) ; Postdoctoral Science Foundation of Heilongjiang Province (LBHQ15087)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Long‐term Hypoxia Alters Cytochrome P450 Activity During Pregnancy in Ovine Species
Authors: Truong Hillary , Lam Tran Chau , Solak Sara , Adeoye Olayemi Olufikayo 
Published: June 2021

The absolute avoidance of medication during pregnancy, though desired, might not be practical because of preexisting co‐morbidities, pregnancy induced disorders (e.g. gestational diabetes), preeclampsia, or even fetal disorders. When indicated, the use of medication could be a major source of stress and apprehension for the pregnant woman and her care‐provider. The inadequacy of data on drug safety during pregnancy is one contributory factor to this apprehension. Compounding this problem is the resurgence of the use of illicit drugs and abuse of prescription medications such as opioids during pregnancy. It is well‐established that drug metabolism is altered during pregnancy. Changes in maternal drug metabolism can also occur during pathologic conditions associated with exposure to varying levels of hypoxia.Cytochrome P450 (CYP) 3A accounts for the metabolism of over 60% of clinically used drugs and environmental xenobiotics. CYP expression is altered by pregnancy as well as pathologies attributable to hypoxia like eclampsia, placental insufficiency and illicit drug use. We hypothesize here that long term hypoxia (LTH) alters CYP activity in pregnant ovine species via epigenetic mechanisms. To generate the hypoxic experimental groups, non‐pregnant and pregnant sheep were taken to an altitude of 3280m above sea level for 110 days while normoxic controls for each group were kept at sea level. Post sacrifice, precise cuts of liver segments were cleaned of blood and assayed for CYP3A4 activity and total methylated cytosines. Compared to their normoxic controls, LTH increased hepatic CYP3A4 catalytic activity in non‐pregnant sheep (118%) and pregnant sheep (142%). Whereas hepatic CYP3A4 catalytic activity was not significantly different between non‐pregnant and pregnant normoxic sheep, it was decreased in pregnant hypoxic sheep (20%) compared to non‐pregnant hypoxic sheep. Western blot quantification revealed no significant changes in CYP3A4 protein abundance between normoxic vs. hypoxic and non‐pregnant vs. pregnant sheep. Lastly, quantified total methylated cytosines (TMC) showed that, compared to their normoxic controls, LTH increased the TMC in non‐pregnant sheep (65%) but decreased (48%) the TMC in pregnant sheep. TMC was increased (38%) in pregnant compared to non‐pregnant normoxic sheep but decreased (56%) in pregnant compared to non‐pregnant hypoxic sheep. Together, these results suggest that gene silencing via CpG methylation of candidate CYP genes may contribute to changes in the catalytic activity of CYP3A4 during pregnancy but not non‐pregnant states.Support or Funding InformationLoma Linda University School of Pharmacy Faculty Scholarship Fund.NIH Program Project Grant from NICHD (HD31266) and an NIH R01 Grant from NINDS (NS076945).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Differences in Peak VO2 Among Healthy Andean Highlanders and Males with Chronic Mountain Sickness Before and After Isovolemic Hemodilution at 4350m
Authors: Heinrich Erica C. , Anza‐Ramirez Cecilia , Tift Michael S. , Marcarlupu Jose Luis , Wagner Harrieth E. , Figueroa‐Mujica Romulo , Vizcardo‐Galindo Gustavo , Gu Wanjun , Wagner Peter D. , Villafuerte Francisco C. , Simonson Tatum S. 
Published: June 2021

Excessive erythrocytosis is the hallmark of Chronic Mountain Sickness (CMS), a maladaptive clinical syndrome common in Andeans that is thought to negatively impact oxygen transport and exercise capacity. We performed cardiopulmonary exercise testing at 4350m in both healthy males (controls) and those with CMS pre‐ and post‐isovolemic hemodilution (n = 8 controls, n = 6 CMS) to determine whether they differed in exercise capacity as a function of hematocrit (Hct). Hct differed significantly between control (Hct=51.6±4.0) and pre‐hemodilution CMS subjects and between pre‐ and post‐hemodilution (Hct=66.7±4.1, 53.2±1.8, respectively; all p<0.0005), and Hct showed a negative trend with exercise capacity in CMS subjects. Anaerobic threshold was lower in CMS subjects compared to controls (p<0.01) but normalized after hemodilution. While peak VO2/kg was similar pre‐ and post‐hemodilution in CMS subjects, it was significantly different between control and CMS subjects with or without hemodilution (p<0.05). Cardiac output (QT/kg) during maximal exercise was lower in pre‐ and post‐hemodilution CMS compared to controls (p<0.02) and was relatively lower in pre‐ versus post‐hemodilution CMS subjects (p<0.05). The slopes of the QT‐VO2 relationship indicate that decreased QT response to exercise in CMS subjects is partially normalized post hemodilution (p<0.04), while the intercept is not statistically different. While QT is reduced in CMS and can be partially recovered by hemodilution, VO2 max did not increase in CMS individuals post hemodilution, suggesting this reduction of Hct does not influence exercise capacity. How the differences between CMS and non‐CMS individuals relate to other components of oxygen transport and the presence and absence of adaptive genetic factors remains to be determined.Support or Funding InformationThis study was supported by an NIH NRSA Individual Postdoctoral Fellowship (Parent F32) to ECH (F32HL131218), a Wellcome Trust PHTM grant (107544/Z/15/Z) to FCV, and an NIH R00HL118215 and American Physiological Society Giles F. Filley Memorial Award to TSS.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Heme‐oxygenase 2 (HMOX2) variants associated with evolutionary adaptation and hemoglobin concentration in Tibetans are common in Andean Highlanders
Authors: Yip Gigi , Heinrich Erica C. , Villafuerte Francisco C. , Simonson Tatum S. 
Published: June 2021

Andean and Tibetan populations have developed distinct adaptations to high altitude. The heme oxygenase 2 gene (HMOX2) is under selection in Tibetans and is associated with hemoglobin concentration in Tibetan men. Putatively adaptive variants within this gene are also prevalent in lowland population but have not been examined in Andean highlanders and could influence variation in hypoxia responses in this population. We genotyped ten variants within the HMOX2 gene region (rs2058812, rs2270363, rs6500606, rs3747584, rs4786509, rs860891, rs8129, rs11639998, rs9934267, and rs17761816) in 128 Quechua Andean highlanders in Cerro de Pasco, Peru (4,350 m) (female = 61; male = 67). We found that the frequencies in Andean highlanders are not as elevated as Tibetans' but similar to those observed in Han Chinese. After controlling for sex and age, there was no significant association between these SNPs and hematocrit (Hct), mean arterial pressure (MAP), oxygen saturation (SpO2), nor hypoxic ventilatory response (HVR). These results suggest that the putatively adaptive high‐altitude HMOX2 variants identified in Tibetans are found at intermediate frequencies in Andeans, although they may not be regulators of hemoglobin concentration in this population.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Autophagy‐Related Protein 16L1 (Atg16L1) Depletion Induces Insulin Resistance Through Decreased IRS Expression
Authors: Frendo‐Cumbo Scott , Jaldin‐Fincati Javier , Brumell John H , Klip Amira 
Published: June 2021

Autophagy is a degradation pathway persisting in all cells at basal levels and further activated by various stimuli, such as starvation. This cellular process is mediated by autophagy‐related (Atg) proteins, which govern cargo recognition and formation of a nascent organelle called the autophagosome. Several Atg proteins have been identified, including Atg3 and the Atg12‐Atg5‐Atg16L1 complex. Recently, connections between autophagy and insulin action have emerged. The insulin receptor (IR) and insulin‐like growth factor receptor (IGF1R) bind and phosphorylate insulin receptor substrate 1 (IRS1) leading to PI3K/Akt activation, which through downstream activation of mTORC1 inhibit autophagy. On the other hand, tissue‐specific, autophagy‐deficient mouse models have attenuated basal and insulin‐stimulated PI3K/Akt signalling. Similarly, expression of the dominant‐negative mutant ATG5K130R in L6 myoblasts reduces insulin‐induced Akt and IRS1 phosphorylation. As growth factor signalling reduces autophagy, these findings suggest a potential feedback mechanism whereby deficient autophagy acts to attenuate insulin signalling. However, the mechanism through which reduced autophagy feeds back onto insulin signalling remains unknown. We hypothesize that interfering with autophagy affects insulin and IGF1 signalling at different levels, including IR, IGF1R and IRS1, and we investigate the potential underlying mechanism. To examine the interplay between deficient autophagy and insulin action, we treated mouse embryonic fibroblasts (MEFs) depleted of Atg3, Atg5, Atg12 or Atg16L1 with 10nM insulin or 100ng/ml (13.3nM) IGF1. Atg depletion did not induce changes in IR content, its localization at the plasma membrane or insulin binding. Interestingly, Atg16L1‐KO MEFs have reduced IRS1 and IRS2 protein content and gene expression, which suggests that defective Atg16L1 affects IRS gene transcription. ER stress is known to reduce Foxo1 protein content, an important transcription factor of IRS, and we have found elevated ER stress in Atg16L1‐KO MEFs. Accordingly, Atg16L1‐ and Atg5‐KO MEFs exhibited attenuated insulin‐ and IGF1‐induced Akt phosphorylation at both S473 and T308 compared to WT. In contrast, insulin‐ and IGF1‐induced Akt phosphorylation was inhibited selectively at T308 in Atg3‐KO MEFs, and at S473 in Atg12 KO MEFs. In conclusion, Atg16L1 appears to induce insulin and IGF1 resistance through decreased IRS1 and IRS2 expression, while Atg3 Atg5 and Atg12 affect signalling at the level of Akt.Support or Funding InformationSFC is funded by NSERC‐CGS.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.