bluuebunny/crossref_metadata_2025_split huggingface dataset:
HIF‐1α regulates a single bout of exercise‐induced hepatic expression of glucose and lipid metabolism related genes
Authors: Luo Beibei , Xiang Dao , Chen Peijie , Hu Yiping 
Published: November 2023

Exercise increases the energy demand, disrupting the hepatic glucose and lipid metabolic homeostasis. A single bout of exercise could induce tissue blood flow redistribution by which the blood flow is decreased in the splanchnic circulation. The hypoxia‐inducible factor (HIF) 1α is pivotal in the transcriptional response to oxygen flux. Therefore, we hypothesize that HIF‐1α plays an important role in the regulation of hepatic metabolism related genes expression after a single bout of exercise. The noninvasive in vivo bioluminescence imaging was applied to monitor HIF‐1α expression after exercise in ROSA26 ODD‐Luc/+ mouse model (ODD‐Luc) that ubiquitously expresses a bioluminescent reporter consisting of firefly luciferase fused to a region of HIF‐1α. We found that one session of 30min swimming exercise markedly increase in vivo HIF‐1α in the gastrointestinal (GI) system and liver. Then two small molecule inhibitors were respectively intraperitoneal (i.p.) injected to the ODD‐Luc mice: DMOG (100mg/kg), which blocks prolyl hydroxylase domain (PHD) protein thus stabilizes HIF‐1α; and PX‐478 (100mg/kg), which inhibits HIF‐1α. The data was shown that the DMOG administration increased in vivo HIF‐1α in the GI system and liver; PX‐478 administration reduced the in vivo HIF‐1α expression after one session of 30min swimming. 8‐week male FVB/N mice were divided into 5 groups (n=6 per group): one session of 30min swimming (SWIM), swimming with PX‐478 i.p. injection (SWIM‐PX478), PX‐478 i.p. injection (PX478), DMOG i.p. injection (DMOG) and control (CON). Gene expression profiling experiments were performed on mouse liver cDNA samples from each group using RT2 Profiler PCR Arrays including over 240 genes related to glucose metabolism, fatty acid metabolism, and lipoprotein signaling and cholesterol metabolism. It was found that one session of exercise‐induced genes expression were significantly different (P<0.001) between the SWIM‐PX478 and SWIM mice, including G6pc, Pck1, Pdk1, Scd1, Acadm, Acox1, Ctp1, Cpt2, Crot, Hmgcs2, Srebf and Ldlr. The pattern of one session of exercise induced hepatic metabolism related genes expression was similar between the DMOG and SWIM groups. Albumin Cre mediated, hepatocyte specific deletions of HIF‐1α or PHD2 mouse models were also developed to verify the function of HIF‐1α in regulating the hepatic glucose and lipid metabolism related genes expression after one session of 30min swimming. In conclusion, these results demonstrate an important role for the HIF‐1α in the regulation of hepatic metabolism related genes expression after a single bout of exercise.Support or Funding InformationThe National Natural Science Foundation of China (31471135) and the China Postdoctoral Science Foundation funded project.
Roux‐en‐Y Gastric Bypass Surgery Enhances Contraction‐Mediated Glucose Metabolism in Primary Human Myotubes
Authors: Hinkley J. Matthew , Zou Kai , Park Sanghee , Turner Kristen , Zheng Donghai , Houmard Joseph A 
Published: November 2023

Contractile activity (e.g. exercise) invokes various metabolic adaptations in skeletal muscle, including improved insulin action and substrate oxidation. However, individuals with metabolic perturbations (i.e. severely obese (BMI ≥ 40 kg/m2) and type 2 diabetics) appear to have inherent defects in the ability to respond to contractile activity. Along with significant weight loss, Roux‐en‐Y gastric bypass (RYGB) surgery elicits positive metabolic adaptations; however, it is uncertain whether this clinical intervention alters the myocellular milieu to respond to contractile activity. To examine this, skeletal muscle cells were isolated from muscle biopsies obtained from patients before and after RYGB surgery, and differentiated into myotubes. Once fully differentiated, myotubes were electrically stimulated to contract for 24 hours (2 ms bipolar pulse, 1 Hz, and 11.5 V), after which changes in metabolic function and intracellular signaling were examined. Myotubes from severely obese patients prior to RYGB surgery were unresponsive to the metabolic benefits of muscle contractile activity, as indicated by a lack of change in insulin‐stimulated glycogen synthesis (38.6% vs. 38.5% increase over basal for control vs. electrical stimulation) and basal glucose oxidation (4.5 nmol glucose/mg/hr vs. 4.6 nmol glucose/mg/hr control vs. electrical stimulation). Interestingly, myotubes derived from the same patients 1‐month post‐RYGB were responsive to muscle contraction, as indicated by an ~1.4‐fold increase in insulin‐stimulated glycogen synthesis (36.9% vs. 52.9% increase over basal for control vs. electrical stimulation) and an ~1.5‐fold increase in basal glucose oxidation (3.9 nmol glucose/mg/hr vs. 5.5 nmol glucose/mg/hr control vs. electrical stimulation). At the molecular level, while unresponsive before surgery, muscle contraction improved insulin‐stimulated phosphorylation of the Rab‐GTPase AS160 1‐month following RYGB surgery (~1.9‐fold vs. ~2.6‐fold insulin stimulation for control vs. electrical stimulation). These data indicate that RYGB surgery inherently improves the ability of skeletal muscle to respond to contractile activity, suggesting an exercise program should be immediately implemented in these patients to further improve substrate metabolism.Support or Funding InformationNIH DK56112
Human Energy Expenditure is in Control of Cytochrome C Oxidase Subunit IV‐2
Authors: Schiffer Tomas A , Ekblom Björn , Sundqvist Michaela Lina , Lundberg Jon O , Weitzberg Eddie , Larsen Filip J 
Published: November 2023

BackgroundThe molecular mechanisms of the pronounced between subject variation in human resting metabolic rate (RMR) remains elusive. The terminal enzyme of the mitochondrial respiratory chain, Cytochrome C oxidase (COX) plays a key role in the control of mitochondrial respiration. There are a number of regulatory mechanisms controlling COX activity and proton pump efficiency. A shift of COX subunit composition may also be a part of the regulation of the enzyme. Recent in vitro studies of COX IV‐2 has implicated this isoform in the cellular response to hypoxia and oxidative stress. The aim of this study was to investigate whether COX IV‐2 is involved in the regulation of respiration in vivo and explains the pronounced individual variations in resting RMR.MethodsIndirect calorimetry was used to measure resting metabolic rate in healthy subjects. Skeletal muscle biopsies were extracted from vastus lateralis for isolation of myogenic satellite cells and protein analysis. Myotubes were transfected with an expression vector in order to achieve over expression of COX IV‐2 and with siRNA for knocking down COX IV‐1 (COX IV‐1−/2+). The control cells were transfected with a control vector and siRNA respectively. Respirometric measurements and hydrogen peroxide production were assessed simultaneously in an oxygraph (O2‐K, Oroboros) equipped with a spectrofluorometer by using the fluorophore Amplex®UltraRed.ResultsHere we show that COX IV‐2 protein is expressed in skeletal muscle harvested from healthy humans with a large inter‐individual difference in the COX IV‐2/COX IV‐1 ratio. A strong inverse correlation was found between the COX IV‐2/COX IV‐1 ratio and RMR measured in the same individuals. The same pattern was observed in the primary human skeletal myotubes overexpressing COX IV‐2 with knocked down COX IV‐1, showing a >60% lower basal cell respiration and a >50% reduction in LEAK respiration. The latter suggests either a lower proton conductance or a reduction in proton slip at COX. In addition, reduced cellular H2O2 production was observed both during LEAK and basal cell respiration.ConclusionThese results suggest an important role of the mitochondrial subunit isoform COX IV‐2 in control of energy expenditure and mitochondrial reactive oxygen species homeostasis in humans.Support or Funding InformationThis study was supported by grants from the Swedish Research Council, Swedish Heart and Lung Foundation, Stockholm City Council (ALF), Swedish National Centre for Research in Sports and funds for the Karolinska Institutet.
Distribution pattern of dietary protein intake does not affect anabolic response, lean body mass, muscle strength or function over 8 weeks in older adults
Authors: Kim Il‐Young , Schutzler Scott , Azhar Gohar , Wolfe Robert , Ferrando Arny 
Published: November 2023

Our recent acute study of dietary protein distribution indicated no difference in the anabolic response to differing patterns of dietary protein intake. However, it has been argued that acute metabolic studies may not predict functional changes over a longer period time. To examine the chronic effects of protein distribution pattern, older subjects (51– 69 yrs) consumed 1.1 g/kg/d in 2 distinct patterns. One group (n=7) consumed protein in a traditional, or uneven, manner (UNEVEN, 15/20/65%; breakfast, lunch, dinner), while the other group (n=7) consumed meals with an even distribution of protein (EVEN: 33/33/33%). Lean body mass (LBM), functional outcomes, and protein kinetics at whole‐body and muscle levels using stable isotope tracers were determined before and after 8 weeks of each respective protein intake pattern. There were no significant differences between the intake patterns in LBM, muscle strength, and other functional outcomes. Consistent with these findings, the 20‐h integrated whole body protein kinetics [net protein balance (NB), protein synthesis (PS), and breakdown (PB)] above basal states and muscle protein synthesis were not different between the intake patterns. We conclude that the distribution pattern of protein intake in mixed meals over an 8‐week period does not affect protein metabolism, lean body mass, muscle strength, or functional outcomes.Support or Funding InformationThe project was financially supported by a grant from National Dairy Council, Egg Nutrition Center, and National Cattlemen's Beef Association. This project was financially supported by Pepper Center Grant PG30‐AG‐028718 and Award Number UL1‐TR‐000039 and KL2‐TR‐000063 from the National Center for Advancing Translations Sciences (NCATS).
Nutritional Status Affects Expression of AMPK mRNA in a Tissue and Subunit‐specific Manner in Channel Catfish
Authors: Evans Paige , Vides Melissa , Teel Brianna , Kobayashi Yasuhiro 
Published: November 2023

The objective of this study was to determine whether AMP Protein Kinase (AMPK) expression is associated with changes in food intake in channel catfish. AMPK is known as the master regulator of nutrient metabolism and has been associated with the development of obesity and other metabolic disorders. An obese‐like phenotype develops in channel catfish genetically selected toward an increased growth rate, suggesting that channel catfish could be a model organism to study the development of obesity and other metabolic disorders. However, the mechanisms associated with the development of the phenotype are unclear. After 28 days, brain, liver and muscle tissues were collected from juvenile catfish that were randomly assigned to one of three different treatments: fasted, fed and fasted‐refed. Expression of mRNA encoding AMPK beta, gamma, and alpha subunits were quantified using real‐time PCR. Expression of AMPK gamma and alpha 2 subunit mRNA in muscle, brain and liver were similar among all treatments (p>0.10). Expression of AMKP beta 1 and 2 subunit mRNA was also similar in muscle among the three treatments (p>0.10). In contrast, expression of AMPK beta 1 (p<0.01) and alpha 1 (p<0.05) subunit mRNA was higher in liver of fasted fish. The results of our study showed that, in channel catfish, changes in food intake influence the expression of AMPK mRNA in tissue‐and subunit‐specific manner. Given the importance of AMPK in the development of obesity, further studies are needed to identify the association between AMPK mRNA expression and the development of an obese‐like phenotype in channel catfish.Support or Funding InformationThis study is supported by the Kansas IDeA Network of Biomedical Research Excellence (grant number P20GM103418).
Long‐term Adaptations in Hepatic Substrate Utilization in 1 Year Old Rat Model of Bronchopulmonary Dysplasia
Authors: Levin Taylor S. , Tetri Laura , Haraldsdottir Kristin , Pegelow David F. , Braun Rudolf K. , Gross Kara N. , Eldridge Marlowe W. 
Published: November 2023

BackgroundApproximately 12% of births in the United States are preterm, and this number is rising globally. Preterm birth is associated with increased long‐term risk for insulin resistance, metabolic syndrome, and cardiovascular disease. Infants born preterm often receive oxygen therapy, which, while life saving, can cause many changes in metabolism at the cellular level, especially in the liver. Hyperoxic exposure can inhibit processes such as glucose‐induced insulin secretion, which is linked to the inhibition of oxidative phosphorylation. We hypothesized that a two‐week postnatal hyperoxic exposure would result in a shift in metabolism from oxidative phosphorylation to a glycolytic pathway in the liver that persists into adulthood.MethodsHarlan Sprague‐Dawley (SD) rat pups were exposed to either 21% oxygen (NORM, n=8; 3 males) or 85% oxygen (HYP, n=13; 6 males) for 14 days beginning within 12 hours of birth. After this 14‐day period, they were placed in room air and aged out to 1 year in standard normoxic conditions, at which point their livers were harvested and flash frozen in liquid nitrogen. Alterations in the expression of key metabolic regulators were analyzed by Western blotting. Key metabolic regulators include phosphofructokinase 1 (PFK‐1), lactate dehydrogenase A (LDHA), pyruvate dehydrogenase (PDH), and phosphorylated PDH (pPDH). The effects of sex and oxygen levels were compared using two‐way ANOVA with Tukey's for multiple comparisons.ResultsExpression of LDHA was increased in male HYP rats as compared to the male NORM group (P=0.02; increase of 36.9%). PDH was downregulated in the male HYP rats as compared to the male NORM rats (P<0.001; decrease of 34.8%). Finally, PFK‐1 is downregulated in the HYP females as compared to NORM females (P=0.001; decrease of 49.9%). There was no significant change in the pPDH/PDH ratio in either sex.ConclusionsPDH converts pyruvate to acetyl‐CoA at the end of glycolysis. Acetyl‐CoA is then used in the TCA cycle to carry out respiration and energy formation. The downregulation of PDH seen in the HYP male group suggests that there is less cellular respiration as a result of postnatal HYP exposure. Together, the upregulation of LDHA and downregulation of PDH suggest that pyruvate is shunted away from the TCA cycle to form lactate. Alternatively, this could represent a downregulation of the TCA cycle and an increased utilization of lactate for gluconeogenesis. Overall, these findings suggest an increase in anaerobic metabolism and a decrease in aerobic metabolism within the liver following postnatal HYP exposure.Support or Funding InformationFunding source: NHLBI, R01 HL115061‐03, Suppl (Eldridge) & NHLBI, R01 HL115061 (Eldridge)
Depletion of murine microbiota with broad‐spectrum antibiotics alters intestinal motility, secretion, and mucosal barrier function
Authors: Lendrum Jonathan , Seebach Bradley , Liu Sumei 
Published: November 2023

The commensal microbiota in the gut coevolved with the mammalian host and is essential for many host physiological processes. Alterations in the composition of gut microbiota seem to be a pathogenic component of functional gastrointestinal disorders. The aim of this study is to investigate if a state of antibiotics‐induced intestinal dysbiosis is able to modify intestinal motility, secretion, and mucosal barrier function. C57BL/6 mice received a broad‐spectrum antibiotic cocktail (ampicillin 25mg/kg, vancomycin 10mg/kg, neomycin 25 mg/kg, and metronidazole 25 mg/kg) by oral gavage once a day for two weeks. Gastrointestinal transit was measured using a charcoal meal method. Ussing chamber techniques were used to assess colonic mucosal ion secretion and transepithelial electrical resistance (TER). Intestinal permeability to macromolecules was assessed by the flux of horseradish peroxidase (HRP, 44kD) from mucosa to serosa side of the colonic mucosa/submucosa preparations. Two weeks of antibiotics treatment delayed gastrointestinal transit. Colonic baseline ion secretion was increased in antibiotics‐treated mice. Antibiotics treatment also caused a dramatic increase in intestinal permeability, which was indicated by a significant reduction of TER and an increase in HRP flux from mucosa to serosa side of the colon. The results of this study suggest that depletion of intestinal microbiota with broad‐spectrum antiobiotics reduces gastrointestinal motility, enhances colonic ion secretion, and impairs mucosal barrier function and may contribute to functional gastrointestinal disorders.Support or Funding InformationNIH R15 DK097460‐01A1 (SL) and UW‐L undergraduate research grant (JL)
Molecular changes leading to the abnormal migration of sacral neural crest cells in the Dominant megacolon mutant, a mouse model of Hirschsprung's disease
Authors: HUANG Taida , HOU Yonghui , CHAN Wood Yee 
Published: November 2023

Although the majority of neurons and glia of the enteric nervous system (ENS) are derived from neural crest cells (NCCs) at the vagal (cervico‐thoracic) level, NCCs at the sacral level are also able to migrate to the hindgut of the developing embryo and contribute significantly to the ENS of the colon. Abnormal migration of NCCs may lead to a loss of enteric neurons and glial cells in humans, which is called Hirschsprung's disease (HSCR), and also in the Dominant megacolon mouse (Dom), which is an animal model of HSCR carrying a spontaneous mutation of Sox10. In this study, we aimed to follow the migration of sacral NCCs in the mutant embryos and determine the molecular events that lead to the abnormal migration of sacral NCCs. It was found with in situ cell labeling and whole embryo culture that migrating sacral NCCs tended to aggregate, resulting in their delayed migration toward the hindgut. Genome‐wide profiling of RNA expression with microarrays showed that the expression of the adhesion molecule cadherin 19 (Cdh19) was drastically down‐regulated in mutant sacral NCCs as compared to that in the wild‐type. Results of in situ hybridization with wild‐type embryos at E9.5 to E11.5 indicated that Cdh19 was localized to migrating sacral NCCs and their derivatives which also expressed Sox10. With luciferase assay and chromatin immunoprecipitation, the expression of Cdh19 was found to be directly regulated by Sox10, and the binding site of Sox10 on the promoter of Cdh19 was also identified. When the expression of Cdh19 was knockdown in the primary culture of wild‐type sacral NCCs, their migration ability was reduced, and conversely, upon re‐expression of Cdh19 in the mutant sacral NCCs, their migration ability was restored to a level close to that of wild‐type sacral NCCs. Further experiments with immunoprecipitation showed that the Cdh19 expression modulated NCCs migration via interacting with catenins which are important regulators of the dynamic cytoskeleton of migrating NCC. In summary, the present study showed that the Sox10 mutation in the Dom mutant resulted in the delayed migration of sacral NCCs and significant down‐regulation of the expression of Cdh19 which was a direct downstream target of Sox10. Alterations of Cdh19 expression changed the migration ability of sacral NCCs through interactions with catenins which in turn regulated the dynamic cytoskeleton of migrating NCCs.Support or Funding InformationThis work was supported by a RGC General ResearchFund (CUHK14102214) and a Direct Research Grant from the Faculty of Medicine, TheChinese University of Hong Kong (2014.1.074).
Lmx1b‐Mediated Limb Dorsalization: Identification of a Potential Regulatory Sequence for Keratocan, Lumican, and Decorin
Authors: Spady Rachael Nicole , Haro Endika , Pira Charmaine U , Feenstra Jennifer M , Oberg Kerby C 
Published: November 2023

Lmx1b is a homeodomain transcription factor expressed within the dorsal limb mesoderm. Lmx1b knock‐out mice develop ventral‐ventral limbs, while ventral overexpression results in dorsal‐dorsal limbs. Our goal is to further characterize Lmx1b‐regulated limb dorsalization by identifying downstream target genes. Gene array studies show up‐regulation of the extracellular matrix genes Keratocan (Ker), Lumican (Lum), and Decorin (Dcn) in the presence of Lmx1b. These three genes are clustered within 134k bp of each other on chromosome 11 in mice. Lmx1b‐targeted chromatin immunoprecipitation followed by massively parallel sequencing (Lmx1b‐ChIP‐seq) identified a potential regulator sequence (PRS), 509 bp in length, located 929 kb downstream of Lum with 3 potential Lmx1b binding sites. We reasoned that Lmx1b binding to this PRS might regulate Ker, Dcn and/or Lum expression during limb dorsalization.To determine activity, the PRS was isolated by PCR, incorporated into a construct with a basal promoter linked to GFP reporter, and then electroporated into the presumptive wing field of stage 14 chick embryos. We co‐transfected a β‐actin promoter‐driven RFP construct with the PRS reporter to confirm transfection efficiency. To determine the requirement for Lmx1b's binding within the PRS, we repeated the experiment following site directed mutagenesis of the predicted Lmx1b binding sites.The PRS is active in the ventral mesoderm of the developing limbs and absent in dorsal limb mesoderm proximally. This suggested that Lmx1b might inhibit activity of this PRS. However, there was no apparent change in enhancer activity after site‐directed mutagenesis of the 3 Lmx1b binding sites. Thus, Lmx1b is not likely to play a direct role in restricting this enhancer from dorsal mesoderm. Further analyses will be required to determine the factors responsible for this unique pattern of enhancer activity.Support or Funding InformationLoma Linda University; National Organization of Rare Diseases (NORD)