Protein deamidation to produce processable ingredients and engineered colloids for emerging food applications.

With the ever-increasing demands for functional and sustainable foods from the general public, there is currently a paradigm shift in the food industry toward the production of novel protein-based diet. Food scientists are therefore motivated to search for natural protein sources and innovative technologies to modify their chemical structure for desirable functionality and thus utilization. Deamidation is a viable, efficient, and attractive approach for modifying proteins owing to its ease of operating, specificity, and cost-effective processes. Over the past three decades, the knowledge of protein deamidation for food applications has evolved drastically, including the development of novel approaches for deamidation, such as protein-glutaminase and ion exchange resin, and their practices in new protein substrate. Thanks to deamidation, enhanced functionalities of food proteins from cereals, legumes, milk, oil seeds and others, and thereby their processabilities as food ingredients have been achieved. Moreover, deamidated proteins have been used to fabricate engineered food colloids, including self-assembled protein particles, protein-metallic complexes, and protein-carbohydrate complexes, which have demonstrated tailored physicochemical properties to modulate oral perception, improve gastrointestinal digestion and bioavailability, and protect and/or deliver bioactive nutrients. Novel bioactivity, altered digestibility, and varied allergenicity of deamidated proteins are increasingly recognized. Therefore, deamidated proteins with novel techno-functional and biological properties hold both promise and challenges for future food applications, and a comprehensive review on this area is critically needed to update our knowledge and provide a better understanding on the protein deamidation and its emerging applications.

Transient p53 inhibition sensitizes aged white adipose tissue for beige adipocyte recruitment by blocking mitophagy.

Aging of white adipose tissue (WAT) is associated with reduced insulin sensitivity, which contributes to whole-body glucose intolerance. WAT aging in mice impairs cold-induced beige adipocyte recruitment (beiging), which has been attributed to the senescence of adipose progenitor cells. Tumor suppressor p53 has also been implicated in WAT aging. However, whether p53-related cellular aging in mature white adipocytes is causative of age-impaired WAT beiging remains unknown. It is also unclear whether transient p53 inhibition can rescue WAT beiging. Herein, we report that p53 increased in adipose tissues of 28-wk-old (aged) mice with impaired beiging capability. Cold exposure decreased p53 in beiging WAT of young mice but not in aged mice. In aged mice, inducible p53 ablation in differentiated adipocytes restored cold-induced WAT beiging and augmented whole-body energy expenditure and insulin sensitivity. Transient pharmacological inhibition of p53 led to the same beneficial effects. Mechanistically, cold exposure repressed autophagy in beiging WAT of young mice yet increased autophagy in aged WAT. p53-ablation reduced microtubule-associated protein light chain 3-mediated mitochondria clearance (mitophagy) and hence facilitated the increase of mitochondria during beiging. These findings suggest that p53-induced mitophagy in aged white adipocytes impedes WAT beiging and may be therapeutically targeted to improve insulin sensitivity in aged WAT.-Fu, W., Liu, Y., Sun, C., Yin, H. Transient p53 inhibition sensitizes aged white adipose tissue for beige adipocyte recruitment by blocking mitophagy.

Ectopic brown adipose tissue formation within skeletal muscle after brown adipose progenitor cell transplant augments energy expenditure.

Brown adipose tissue (BAT) thermogenesis increases energy expenditure (EE). Expanding the volume of active BAT via transplantation holds promise as a therapeutic strategy for morbid obesity and diabetes. Brown adipose progenitor cells (BAPCs) can be isolated and expanded to generate autologous brown adipocyte implants. However, the transplantation of brown adipocytes is currently impeded by poor efficiency of BAT tissue formation in vivo and undesirably short engraftment time. In this study, we demonstrated that transplanting BAPCs into limb skeletal muscles consistently led to the ectopic formation of uncoupling protein 1 (UCP1)+pos adipose tissue with long-term engraftment (>4 mo). Combining VEGF with the BAPC transplant further improved BAT formation in muscle. Ectopic engraftment of BAPC-derived BAT in skeletal muscle augmented the EE of recipient mice. Although UCP1 expression declined in long-term BAT grafts, this deterioration can be reversed by swimming exercise because of sympathetic activation. This study suggests that intramuscular transplantation of BAPCs represents a promising approach to deriving functional BAT engraftment, which may be applied to therapeutic BAT transplantation and tissue engineering.-Liu, Y., Fu, W., Seese, K., Yin, A., Yin, H. Ectopic brown adipose tissue formation within skeletal muscle after brown adipose progenitor cell transplant augments energy expenditure.

Targeting RyR2 with a phosphorylation site-specific nanobody reverses dysfunction of failing cardiomyocytes in rats.

Chronic PKA phosphorylation of ryanodine receptor 2 (RyR2) has been shown to increase diastolic sarcoplasmic reticulum (SR) Ca2+ leakage and lead to cardiac dysfunction. We hypothesize that intracellular gene delivery of an RyR2-targeting phosphorylation site-specific nanobody could preserve the contractility of the failing myocardium. In the present study, we acquired RyR2-specific nanobodies from a phage display library that were variable domains of Camelidae heavy chain-only antibodies. One of the nanobodies, AR185, inhibited RyR2 phosphorylation in vitro and was chosen for further investigation. We investigated the potential of adeno-associated virus (AAV)9-mediated cardiac expression of AR185 to combat postischemic heart failure (HF). AAV gene delivery elevated the intracellular expression of the AR185 protein in a rat model of ischemic HF, and this treatment normalized the systolic and diastolic dysfunction of the failing myocardium in vivo by reversing myocardial Ca2+ handling. Furthermore, AR185 gene transfer to failing cardiomyocytes reduced the frequency of SR calcium leaks, thereby restoring the attenuated intracellular calcium transients and SR calcium load. Moreover, AR185 gene transfer inhibited the PKA-mediated phosphorylation of RyR2 in failing cardiomyocytes. Our results provide preclinical experimental evidence that the cardiac expression of RyR2 nanobodies with AAV9 vectors is a promising therapeutic strategy for HF.-Li, T., Shen, Y., Lin, F., Fu, W., Liu, S., Wang, C., Liang, J., Fan, X., Ye, X., Tang, Y., Ding, M., Yang, Y., Lei, C., Hu, S. Targeting RyR2 with a phosphorylation site-specific nanobody reverses dysfunction of failing cardiomyocytes in rats.

Right atrial appendage aneurysm complicated with atrial septal defect: A rare case report.

Right atrial appendage aneurysms (RAAAs) are rare heart malformations, presenting as isolated anomalies or co-existing with other structural heart diseases. We describe a rare case of RAAA complicated with an atrial septal defect (ASD). The diagnosis was established using transthoracic echocardiography and confirmed using cardiac magnetic resonance imaging. To treat the ASD and reduced right atrium volume load, ASD transcatheter closure was performed. On echocardiography performed 3 months post discharge, the RAAA was observed to have reduced in size compared to that presurgery. Six years later, she was in good condition without any adverse events.

Treatment of murine lupus with TIGIT-Ig.

The TIGIT (T cell immunoreceptor with Ig and ITIM domains) protein is a co-inhibitory receptor that has been reported to suppress autoreactive T and B cells to trigger immunological tolerance. We generated a new recombinant protein by connecting the extracellular domain of murine TIGIT to the Fc region of the mouse immunoglobulin IgG2a. The fusion protein was then characterized. The results suggested that among mice with lupus that were treated with the TIGIT-Ig fusion protein, the onset of proteinuria was delayed, serum concentrations of autoantibodies, such as antinuclear antibodies, were reduced without a decrease in the total IgG concentrations, and the survival rate was significantly increased compared to those of the controls. In conclusion, TIGIT-Ig administration showed promising results for both the prevention and treatment of autoimmune diseases in mice. This indicates that treatment with recombinant human TIGIT-Ig shows promise as an effective way to treat human autoimmune diseases.

Age-Associated Sirtuin 1 Reduction in Vascular Smooth Muscle Links Vascular Senescence and Inflammation to Abdominal Aortic Aneurysm.

RATIONALE: Uncontrolled growth of abdominal aortic aneurysms (AAAs) is a life-threatening vascular disease without an effective pharmaceutical treatment. AAA incidence dramatically increases with advancing age in men. However, the molecular mechanisms by which aging predisposes individuals to AAAs remain unknown. OBJECTIVE: In this study, we investigated the role of SIRT1 (Sirtuin 1), a class III histone deacetylase, in AAA formation and the underlying mechanisms linking vascular senescence and inflammation. METHODS AND RESULTS: The expression and activity of SIRT1 were significantly decreased in human AAA samples. SIRT1 in vascular smooth muscle cells was remarkably downregulated in the suprarenal aortas of aged mice, in which AAAs induced by angiotensin II infusion were significantly elevated. Moreover, vascular smooth muscle cell-specific knockout of SIRT1 accelerated angiotensin II-induced formation and rupture of AAAs and AAA-related pathological changes, whereas vascular smooth muscle cell-specific overexpression of SIRT1 suppressed angiotensin II-induced AAA formation and progression in Apoe-/- mice. Furthermore, the inhibitory effect of SIRT1 on AAA formation was also proved in a calcium chloride (CaCl2)-induced AAA model. Mechanistically, the reduction of SIRT1 was shown to increase vascular cell senescence and upregulate p21 expression, as well as enhance vascular inflammation. Notably, inhibition of p21-dependent vascular cell senescence by SIRT1 blocked angiotensin II-induced nuclear factor-κB binding on the promoter of monocyte chemoattractant protein-1 and inhibited its expression. CONCLUSIONS: These findings provide evidence that SIRT1 reduction links vascular senescence and inflammation to AAAs and that SIRT1 in vascular smooth muscle cells provides a therapeutic target for the prevention of AAA formation.

High expression of COX5B is associated with poor prognosis in breast cancer.

BACKGROUND: Cytochrome c oxidase subunit VB (COX5B), a subunit of mammalian COX, takes roles in COX assembling and functions. Online database predicts high COX5B transcription may be associated with worse disease-free survival (DFS). However, the clinical implications of COX5B in breast cancer remain unclear. METHODS: We carried out immunohistochemistry on tissue microarrays of 244 patients with invasive ductal breast carcinoma to detected COX5B expression. RESULTS: Our results suggest that COX5B protein level might be associated with tumor size. COX5B overexpression indicated a worse DFS (p < 0.05) in breast cancer. Furthermore, high COX5B expression may act as an independent factor for worse DFS in breast cancer. CONCLUSIONS: Cumulatively, our findings suggest that COX5B might serve as an important prognostic factor for breast cancer.

Exogenous administration of chronic corticosterone affects hepatic cholesterol metabolism in broiler chickens showing long or short tonic immobility.

Tonic immobility (TI) is an innate characteristic of animals related to fear or stress response. Animals can be classified into long TI (LTI) and short TI (STI) phenotypes based on TI test duration. In this study, effect of TI phenotype, chronic corticosterone administration (CORT), and their interaction on cholesterol metabolism in liver was evaluated in broilers. LTI broilers showed higher level of cholesterol in liver compared to STI chickens (p<0.05), and CORT significantly increased hepatic cholesterol content (p<0.01). Real-time PCR results showed that both TI and CORT potentially altered ABCA1 and CYP7A1 gene expressions (0.05

Structure-based development and optimization of therapy antibody drugs against TNFα.

Previously, we reported on the crystal structures of the Fab fragments of two food and drug administration approved therapeutic antibodies, Infliximab and Adalimumab, in complex with TNFα. The structurally identified epitopes on TNFα reveal the mechanism of TNFα inhibition by partially overlapping with the TNFα-receptor interface. In this study, we launched a screen of a phage display library to isolate novel anti-TNFα antibodies based on the adalimumab epitope. Structural analysis, the phage display antibody isolation technology, step-by-step antibody optimization, complementarity-determining region residues random mutagenesis, phage ELISA, binding affinity characterization, and cell signaling assays were used for the development and optimization of the novel anti-TNFα antibodies. Moreover, one of the novel antibodies, hAta09, has a superior inhibitory effect on TNFα function and signaling. Taken together, our report established that the novel anti-TNFα antibody hAta09 may achieve clinical efficacy in a TNFα-associated disease.

Risk of severe diarrhea with dual anti-HER2 therapies: a meta-analysis.

Although promising progress has been made with dual HER2 blockade in patients with HER2-positive breast cancer, whether the strategy of combined HER2 blockade increases the risk of severe diarrhea remains inclusive. In the present study, we investigated the overall incidence and risk of severe diarrhea when patients were treated with a combination of anti-HER2 therapies compared to anti-HER2 monotherapy. Studies that evaluated the administration of an anti-HER2 monotherapy (lapatinib or trastuzumab or pertuzumab) versus anti-HER2 combination therapy (pertuzumab plus trastuzumab or trastuzumab plus lapatinib) in breast cancer were identified from the PubMed database (1966-2013), the Cochrane library, abstracts presented at the American Society of Clinical Oncology annual conference (2004-2013), and the Web of Science database (1998-2013). Eligible studies were those in which the only systematic difference between the study arms was the type of anti-HER2 therapy used. Incidence, relative risk (RR), and 95% confidence intervals (CIs) were calculated using random effects or fixed-effects models based on the heterogeneity of the included studies. Seven trials were considered eligible. The overall incidence results for severe diarrhea in the combined anti-HER2 therapy and the anti-HER2 monotherapy were 3.48% (95% CI: 11.60-15.37%) and 8.68% (9 % CI: 7.33-10.03%), respectively. The odds ratio (OR) of severe diarrhea between anti-HER2 combination therapy and monotherapy was 1.67 (95% CI: 1.38 -5.57, p = 0.00001). This meta-analysis provides evidence that the incidence rates of severe diarrhea are comparable between anti-HER2 combination therapy and anti-HER2 monotherapy.

Effects of tonic immobility (TI) and corticosterone (CORT) on energy status and protein metabolism in pectoralis major muscle of broiler chickens.

Tonic immobility (TI), which can be divided into short (STI) or long (LTI) duration, is a character related to fear. Our previous study has demonstrated LTI phenotype and chronic corticosterone (CORT) administration retarded growth of breast muscle in broiler chickens. In order to investigate the mechanism behind the negative effects of LTI and CORT on growth, the level of mRNA transcription of several key genes linked to energy and protein metabolism was measured in muscle. LTI broilers showed lower levels of ATP, energy charge (EC) (p<0.01), and lower muscle glycogen content (p<0.05) but higher level of ADP (p = 0.08) than STI birds. CORT treatment elevated EC level (p<0.05) and reduced liver glycogen content (p<0.05). Real-time PCR results showed that STI chickens had higher mRNA expression of PPAR α (p = 0.06) and AMPK α (p = 0.09) than LTI. CORT significantly down-regulated α-enolase mRNA expression in breast muscle compared to control (p<0.05). Neither TI nor CORT altered gene expression in Akt/mTOR/p70s6k cascade pathway in muscle (p > 0.05). However, western blot results showed that LTI chickens exhibited higher protein content of total Akt (p = 0.05) and phosphorylated Akt (p = 0.06) than STI. CORT treatment decreased the total protein content of Akt (p = 0.09) and p70s6k (p = 0.08). These results suggest that the retardation of muscle growth by LTI and chronic CORT administration parallels a strong alternation in energy status but slight changes of Akt/mTOR/p70s6k cascade, indicating that a decrease in muscle growth induced by LTI and CORT might not be mediated through mTOR-dependent signaling pathways.

Cholesterol deregulation induced by chronic corticosterone (CORT) stress in pectoralis major of broiler chickens.

Chronic endogenous glucocorticoid (GC) excess in mammals is associated with metabolic dysfunction and dyslipidemia that are characterized by increased plasma triglyceride and total cholesterol (Tch) levels. However, the effects of chronic GC administration on cholesterol metabolism, particularly in muscle tissues of broiler chickens, are unknown. In this study, broiler chickens were treated chronically with vehicle (CON) or corticosterone (CORT) for 2 weeks. Chronic CORT treatment significantly increased Tch levels in pectoralis major muscle (PMC) (p<0.001) as well as in leg muscle (p<0.01), and CORT enhanced triglyceride levels in the PMC (p<0.001). Real-time PCR results showed that HMGCR (p<0.05) mRNA expression was up-regulated by CORT in PMC, and 11ß-HSD1 gene transcription (p=0.08) was not significantly downregulated, whereas glucocorticoid receptor (GR) mRNA expression, 11ß-HSD2, CYP7A1, CYP27A1, ApoB and LDLR were unchanged by CORT (p>0.05). Western blot results showed that the levels of total GR (p=0.08) tended to be increased and nuclear GR protein (p<0.05) was increased in PMC by CORT administration. Parallel to an increase in gene expression, HMGCR protein expression in PMC was significantly increased (p<0.05) by CORT. Moreover, LDLR (p<0.05), ApoA1 (p=0.06) and 11ß-HSD2 (p=0.07) protein expression in PMC tended to be increased by CORT compared to control. These results indicate that chronic CORT administration causes cholesterol accumulation in PMC tissues of broiler chickens by increasing cholesterol synthesis and uptake.

Comparative proteomic analysis of the breast muscle response to chronic corticosterone administration in broiler chickens showing long or short tonic immobility.

Broilers of the same genetic origin were classified as short or long tonic immobility duration (STI and LTI, respectively) phenotypes and treated chronically with vehicle (control) or corticosterone (CORT) dissolved in drinking water between 27 and 42 d of age. Differential expression of proteins and mRNA was examined using 2-dimensional gel electrophoresis and real-time PCR to elucidate the mechanism behind the severe retardation of broiler breast muscle growth caused by LTI and CORT. The majority of the 13 proteins found to be differentially expressed in breast muscle of STI and LTI broilers are involved in either glycolysis (5 proteins) or myofilament formation (5 proteins). Of the 16 proteins differentially expressed in breast muscle following CORT treatment, 6 are structural proteins, 5 are categorized as cellular defense and stress proteins, and 3 (pyruvate kinase, l-lactate dehydrogenase, and creatine kinase) are involved in responses to stress and muscle damage. Real-time PCR results indicated that expression of these proteins is transcriptionally and posttranscriptionally regulated. Protein synthesis capacity, estimated by the RNA-to-protein ratio, was significantly lower in the breast muscle of CORT-treated broilers than in untreated control broilers. The level of Leu, Gly, and Ser in serum was significantly higher in CORT-treated broilers than in the control birds. Therefore, we conclude that CORT treatment retards the growth of skeletal muscle by suppressing protein synthesis and augmenting protein catabolism, paralleling the response to severe stress and muscle damage, and the negative effect of LTI on muscle growth is likely mediated through glucose metabolism. No interaction was observed between CORT and tonic immobility affecting growth performance or any parameter examined in the current study.

Gypenosides protected the neural stem cells in the subventricular zone of neonatal rats that were prenatally exposed to ethanol.

Fetal alcohol spectrum disorder (FASD) can cause severe mental retardation in children who are prenatally exposed to ethanol. The effects of prenatal and early postnatal ethanol exposure on adult hippocampal neurogenesis have been investigated; however, the effects of prenatal ethanol exposure on the subventricular zone (SVZ) have not. Gypenosides (GPs) have been reported to have neuroprotective effects in addition to other bioactivities. The effects of GPs on neural stem cells (NSCs) in the FASD model are unknown. Here, we test the effect of prenatal ethanol exposure on the neonatal SVZ, and the protection potential of GPs on NSCs in FASD rats. Our results show that prenatal ethanol exposure can suppress the cell proliferation and differentiation of neural stem cells in the neonatal SVZ and that GPs (400 mg/kg/day) can significantly increase the cell proliferation and differentiation of neural stem cells inhibited by ethanol. Our data indicate that GPs have neuroprotective effects on the NSCs and can enhance the neurogenesis inhibited by ethanol within the SVZ of neonatal rats. These findings provide new evidence for a potential therapy involving GPs for the treatment of FASD.

Exosomes: the next frontier in vaccine development and delivery.

Exosomes are small disk-shaped extracellular vesicles (EVs) that are naturally released into the environment by different types of cells. Exosomes range from 30-150 nm in size and contain complex RNA and proteins. They are widely found in body fluids such as blood, saliva, urine and breast milk and participate in cell communication by functioning as cell messengers. Almost all cell types can transmit information and exchange substances through the production and release of exosomes to regulate proliferation, differentiation, apoptosis, the immune response, inflammation, and other biological functions. Because exosomes exist widely in various body fluids, they are easy to obtain and detect and have the potential for use in disease diagnosis and prognosis detection. Exosomes can be genetically fused with targeted proteins, enhancing their biocompatibility and immunogenicity. Therefore, exosomes are the preferred vector tools for vaccines. In this review, we describe the characteristics of exosomes and discuss their unique and ambiguous functions in the immune microenvironment after infection. In this regard, we explored the ability of exosomes to carry immunogenic virus antigens and to establish adaptive immune responses. Exosomes can provide an interesting platform for antigen presentation and since vaccines are a powerful method for the prevention of infectious diseases, we further review the advantages and disadvantages of the use of exosomes in vaccine preparation. Overall, exosomes are emerging as a promising avenue for vaccine development.

The therapeutic potential of exosomes in immunotherapy.

Exosomes are found in various tissues of the body and carry abundant contents including nucleic acids, proteins, and metabolites, which continuously flow between cells of various tissues and mediate important intercellular communication. In addition, exosomes from different cellular sources possess different physiopathological immunomodulatory effects, which are closely related to the immune regeneration of normal or abnormal organs and tissues. Here, we focus on the mechanistic interactions between exosomes and the human immune system, introduce the immuno-regenerative therapeutic potential of exosomes in common clinical immune-related diseases, such as infectious diseases, autoimmune diseases, and tumors, and reveal the safety and efficacy of exosomes as a novel cell-free immune regenerative therapy.

Small extracellular vesicles purification and scale-up.

Exosomes are small extracellular vesicles (sEVs) secreted by cells. With advances in the study of sEVs, they have shown great potential in the diagnosis and treatment of disease. However, sEV therapy usually requires a certain dose and purity of sEVs to achieve the therapeutic effect, but the existing sEV purification technology exists in the form of low yield, low purity, time-consuming, complex operation and many other problems, which greatly limits the application of sEVs. Therefore, how to obtain high-purity and high-quality sEVs quickly and efficiently, and make them realize large-scale production is a major problem in current sEV research. This paper discusses how to improve the purity and yield of sEVs from the whole production process of sEVs, including the upstream cell line selection and cell culture process, to the downstream isolation and purification, quality testing and the final storage technology.

Chronic hypoxia impairs skeletal muscle repair via HIF-2α stabilization.

BACKGROUND: Chronic hypoxia and skeletal muscle atrophy commonly coexist in patients with COPD and CHF, yet the underlying physio-pathological mechanisms remain elusive. Muscle regeneration, driven by muscle stem cells (MuSCs), holds therapeutic potential for mitigating muscle atrophy. This study endeavours to investigate the influence of chronic hypoxia on muscle regeneration, unravel key molecular mechanisms, and explore potential therapeutic interventions. METHODS: Experimental mice were exposed to prolonged normobaric hypoxic air (15% pO2, 1 atm, 2 weeks) to establish a chronic hypoxia model. The impact of chronic hypoxia on body composition, muscle mass, muscle strength, and the expression levels of hypoxia-inducible factors HIF-1α and HIF-2α in MuSC was examined. The influence of chronic hypoxia on muscle regeneration, MuSC proliferation, and the recovery of muscle mass and strength following cardiotoxin-induced injury were assessed. The muscle regeneration capacities under chronic hypoxia were compared between wildtype mice, MuSC-specific HIF-2α knockout mice, and mice treated with HIF-2α inhibitor PT2385, and angiotensin converting enzyme (ACE) inhibitor lisinopril. Transcriptomic analysis was performed to identify hypoxia- and HIF-2α-dependent molecular mechanisms. Statistical significance was determined using analysis of variance (ANOVA) and Mann-Whitney U tests. RESULTS: Chronic hypoxia led to limb muscle atrophy (EDL: 17.7%, P < 0.001; Soleus: 11.5% reduction in weight, P < 0.001) and weakness (10.0% reduction in peak-isometric torque, P < 0.001), along with impaired muscle regeneration characterized by diminished myofibre cross-sectional areas, increased fibrosis (P < 0.001), and incomplete strength recovery (92.3% of pre-injury levels, P < 0.05). HIF-2α stabilization in MuSC under chronic hypoxia hindered MuSC proliferation (26.1% reduction of MuSC at 10 dpi, P < 0.01). HIF-2α ablation in MuSC mitigated the adverse effects of chronic hypoxia on muscle regeneration and MuSC proliferation (30.9% increase in MuSC numbers at 10 dpi, P < 0.01), while HIF-1α ablation did not have the same effect. HIF-2α stabilization under chronic hypoxia led to elevated local ACE, a novel direct target of HIF-2α. Notably, pharmacological interventions with PT2385 or lisinopril enhanced muscle regeneration under chronic hypoxia (PT2385: 81.3% increase, P < 0.001; lisinopril: 34.6% increase in MuSC numbers at 10 dpi, P < 0.05), suggesting their therapeutic potential for alleviating chronic hypoxia-associated muscle atrophy. CONCLUSIONS: Chronic hypoxia detrimentally affects skeletal muscle regeneration by stabilizing HIF-2α in MuSC and thereby diminishing MuSC proliferation. HIF-2α increases local ACE levels in skeletal muscle, contributing to hypoxia-induced regenerative deficits. Administration of HIF-2α or ACE inhibitors may prove beneficial to ameliorate chronic hypoxia-associated muscle atrophy and weakness by improving muscle regeneration under chronic hypoxia.

Effect of corticosterone on growth and welfare of broiler chickens showing long or short tonic immobility.

Tonic immobility (TI) test is commonly used to assess fear. Animals showing different TI durations demonstrate distinct behavior and biochemical responses to stress. However, less is known about how TI phenotype affects growth and welfare of domestic fowl. In this study, broiler chickens (Gallus gallus) were classified into short and long TI duration (STI and LTI) phenotypes and treated chronically with vehicle (CON) or corticosterone (CORT). STI broilers demonstrated significantly higher growth rate with higher breast muscle yield (P<0.05) and liver weight relative to BW tended to be lower (P=0.053), which was accompanied by higher serum concentration of CORT (P<0.05) and uric acid (P<0.01), but lower serum level of T4 (P=0.01). CORT severely reduced body weight, as well as the relative weight of muscle, bursa of Fabricius and spleen (P<0.001), but relative liver weight was increased (P<0.001). CORT-treated chickens had reduced serum CORT, elevated heterophile/lymphocyte ratio, and increased serum levels of total and free T3. STI broilers displayed more preening behavior (P<0.05), yet CORT elicited more walking behavior (P<0.05). No difference was observed in the welfare assessment scores between STI and LTI phenotypes under basal situation, while LTI chickens showed significantly increased incidence of pad dermatitis compared to STI under CORT exposure. The results suggest that STI broilers demonstrate better growth performance and higher adaptability to stress compared to LTI chickens.