ABSTRACT
Adipose tissue is a major energy storage and endocrine organ. Adipogenesis is a complex process of cell differentiation, which is regulated by nutrient levels, hormones and metabolites, etc. The mammalian target of rapamycin (mTOR) complex includes two protein complexes, mammalian target of rapamycin complex 1 (mTORC1) and mTORC2. The lipid kinase-like domain contained in the mTOR complex lays the foundation for the mTOR pathway to regulate adipogenesis. Research on some components of mTORC1 and mTORC2 has verified the roles of mTOR in the regulation of adipogenesis. Based on previous studies, we reviewed the research of miR-199a-3p, miR-103, miR-188, Src-associated substrate in mitosis of 68 kD (Sam68), endostatin and other substances in the regulation of adipogenesis through mTORC1 and mTORC2. At the same time, we had further constructed the adipogenesis network regulated by mTOR signaling pathway, including insulin/IGF pathway, PI3K-AKT pathway, amino acid pathway, AMPK pathway, cAMP pathway, cGMP pathway, NOTCH pathway, and the modulation of bta-miR-150, 4-O-methylasochlorin and a variety of proteins. This article mainly reviewed the characteristics of mTOR complex and the latest research progress in the regulation of adipogenesis by mTOR pathway. It was pointed out that mTORC2 can regulate lipid uptake, lipolysis and regulate the function of mTORC1. However, there are fewer studies on mTORC2 compared to mTORC1, so further researches on adipogenesis and lipid metabolism may be more focused on mTORC2.
ABSTRACT
Objectives@#To 1) report prevalence of ‘osteosarcopenia’ (OS) and osteosarcopenic obesity (OSO) entities using evidence-based diagnostic techniques and definitions, 2) examine if OSO offers additional predictive value of functional decline over its components, and 3) identify associated factors in a multi-racial Southeast Asian population. @*Methods@#We performed a cross-sectional study of a representative sample of 542 community-dwelling adults (21–90 years old), and assessed anthropometry, cognition, functional performance, and self-report sociodemographic, health and lifestyle questionnaires. Low muscle mass, and the Asian Working Group for Sarcopenia (AWGS) 2019 criteria, were used to assess sarcopenia. Obesity was defined using percentage body fat and fat mass index. Osteopenia/osteoporosis was determined using lumbar spinal bone mineral density. Associated factors were examined using logistic regression, and OSO’s value investigated using linear regressions with functional performance. @*Results@#OS and OSO prevalence were 1.8% and 0% (21–59 years), 12.9% and 2.8% (≥ 60 years), 17.3% and 4.1% (≥ 65 years), and 25.5% and 7.0% (≥75 years), respectively. OSO entity as defined was not a significant predictor (P > 0.05) and did not improve explanations for functional decline over sarcopenia or sarcopenic obesity. Age, sex, race and body mass index (BMI) were associated with OS, while age, sex, race and alcoholism were associated with OSO. @*Conclusions@#Our results do not support OSO as a distinct entity in relation to functional decline. Aside from biological age, sex, and race, amenable lifestyle factors such as BMI and alcohol intake are important variables that can influence the co-existence of osteopenia/osteoporosis, sarcopenia and obesity.
ABSTRACT
Skeletal muscle is an important tissue of human and livestock. The study of the muscle development is of great significance for treating muscle diseases and improving livestock meat quality. The process of muscle development is controlled by several myogenic transcription factors and signaling pathways. In addition, recent findings established that several noncoding RNAs play a critical role in the regulation of muscle development such as long non-coding RNA (lncRNA), microRNA (miRNA) and circu- lar RNA (circRNA), etc. The detailed mechanism of muscle development is not well understood. Transfer RNAs (tRNAs) are fundamental components in the translation machinery as an adaptor molecule, and tRNA pool could be differentially exploited to modulate expression of mRNAs. In addition, tRNA can be cleaved into tRNA-derived fragments (tRFs) by a variety of ribonucleases (RNases) upon various stress conditions. Unlike the post-transcriptional regulation of lncRNA and miRNA on muscle development, tRNA has been implicated in various aspects of muscle development. Mitochondria play a central role in a plethora of processes related to the maintenance of muscle cellular homeostasis and genomic integrity. Mitochondrial tRNA(mt-tRNA) gene mutations lead to multiple myopathy because human mitochondrial genome is extremely small. The regulation of tRF is similar to miRNAs in regards to the related physiological processes, but are more conservative than miRNA. It is generally believed that tRF has strong tissue specificity, disease specificity and temporal specificity. Some skeletal muscle-specific tRFs could act posttranscriptionally via RNAi or targeting related genes. However, the tRF-sequencing analysis and functional mechanism of tRF are rarely studied in skeletal muscles. The myopathy caused by mitochondrial tRNA gene mutations are particularly complex, which are one of the challenges to diagnose, treat, or prevent diseases. Compared with other noncoding RNAs, the structural complexity of tRF also brings great challenges to data mining and analysis. In this review, we summarize the formation and function of tRNA and tRF especially in muscle development, which will deepen our understandings of related myopathy, and provide new ideas and directions for the investigation of skeletal muscle.
ABSTRACT
Besides UCP1-dependent thermogenesis pathways, UCP1-independent thermogenesis pathways also could increase heat production in adipose tissue to combat obesity. N-Acyl amino acids (NAAs) have been suggested as novel endogenous uncouplers to induce mitochondria UCP1-independent thermogenesis in adipose tissue. Here, we use mouse skeletal muscle C2C12 cells which lack of UCP1 as UCP1 negative cell models. Comparing with its corresponding common fatty acid—oleate, one of the NAAs—N-Oleoylglycine (NOGly), which is highly expressed in the plasma of HFD mice, is selected to study their effects and mechanisms on mitochondrial thermogenesis. We found that 60 μmol / L oleate could induce mitochondrial oxidative phosphorylation protein levels, as well as increase mitochondria thermogenesis-related genes (COX8b, DIO2, UCP3) expression (P < 0. 05) . However, 60 μmol / L NOGly damaged the production and oxidative phosphorylation of mitochondria, significantly down-regulated expression of thermogenic genes (PGC1a, COX8b, COX2, DIO2, UQCRFS1and UCP3) (P< 0. 01), induced the production of reactive oxygen species (ROS) in the mitochondria, and enhanced the oxidative stress in cells. Our study found that oleate can induce UCP1-independent thermogenesis under 60 μmol / L addition dose, whereas NOGly does not due to the induction of oxidative stress in cells.
ABSTRACT
Objectives@#To 1) report prevalence of ‘osteosarcopenia’ (OS) and osteosarcopenic obesity (OSO) entities using evidence-based diagnostic techniques and definitions, 2) examine if OSO offers additional predictive value of functional decline over its components, and 3) identify associated factors in a multi-racial Southeast Asian population. @*Methods@#We performed a cross-sectional study of a representative sample of 542 community-dwelling adults (21–90 years old), and assessed anthropometry, cognition, functional performance, and self-report sociodemographic, health and lifestyle questionnaires. Low muscle mass, and the Asian Working Group for Sarcopenia (AWGS) 2019 criteria, were used to assess sarcopenia. Obesity was defined using percentage body fat and fat mass index. Osteopenia/osteoporosis was determined using lumbar spinal bone mineral density. Associated factors were examined using logistic regression, and OSO’s value investigated using linear regressions with functional performance. @*Results@#OS and OSO prevalence were 1.8% and 0% (21–59 years), 12.9% and 2.8% (≥ 60 years), 17.3% and 4.1% (≥ 65 years), and 25.5% and 7.0% (≥75 years), respectively. OSO entity as defined was not a significant predictor (P > 0.05) and did not improve explanations for functional decline over sarcopenia or sarcopenic obesity. Age, sex, race and body mass index (BMI) were associated with OS, while age, sex, race and alcoholism were associated with OSO. @*Conclusions@#Our results do not support OSO as a distinct entity in relation to functional decline. Aside from biological age, sex, and race, amenable lifestyle factors such as BMI and alcohol intake are important variables that can influence the co-existence of osteopenia/osteoporosis, sarcopenia and obesity.
ABSTRACT
1 approximately 3 days old Piglet's primary preadipocytes in vitro were cultured and treated with 0micromol/L (control group), 10microlmol/L (lower dose group), 20micromol/L(middle dose group) and 50micromol/L, 100micromol/L (higher dose group) RES. Cell proliferation and viability were analyzed by MTT assay. The degree of differentiation and adipogenesis were measured by Oil Red O staining extraction assay and the expression of Sirt1 (sirtuin) mRNA were detected by RT-PCR. The results showed the optical density (OD) of MTT and Oil Red O staining were all decreased, especially treated by 50micromol/L, 100micromol/L RES at 72h and 96h (P < 0.01); the ratio of OD of the expression of Sirt1 mRNA to that of beta-actin mRNA were increased after treated by 100micromol/L RES (P < 0.01). RES can inhibit proliferation and differentiation of pig preadipocytes in certain degree. Higher dose of RES can markedly decrease adipogenesis and prevent preadipocytes differentiation into adipocytes, which may be in part associated with its effect on increasing the expression of Sirt1 mRNA.
Subject(s)
Animals , Adipocytes , Cell Biology , Metabolism , Cell Differentiation , Cell Proliferation , Cells, Cultured , RNA, Messenger , Sirtuin 1 , Genetics , Stem Cells , Stilbenes , Pharmacology , Swine , Transcription, GeneticABSTRACT
Objective To study the changes of anticoagulation and fibrinolysis in neonatal respiratory distress syndrome(NRDS).Methods The levels of plasma protein C(PC),total protein S(TPS),antithrombin Ⅲ(AT-Ⅲ), D-Dimer(D-D) and von Willebrand factor(vWF) were measured with ELSIA assay and immunoturbidimetry in 27 cases NRDS, 20 cases prematures and 15 cases full-term newborns as normal controls.Results The levels of PC, TPS and AT-Ⅲ were lower, but the levels of D-D and vWF were significantly higher than those of prematures and normal controls.The PC,TPS of prematures were lower than normal controls otherwise there is no difference of AT-Ⅲ,D-D,vWF between prematures and normal controls. Conclusions There exists the activation of anticoagulation and fibrinolysis and the injury of vascular endothelium in critical NRDS, and they are early sensitive indexes for the diagnosis of disseminated intravascular coagulation(DIC).