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Although 5-methylcytosine (m 5 C) has been identified as a novel and abundant mRNA modification and associated with energy metabolism, its regulation function in adipose tissue and skeletal muscle is still limited. This study aimed at investigating the effect of mRNA m 5 C on adipogenesis and myogenesis using Jinhua pigs (J), Yorkshire pigs (Y) and their hybrids Yorkshire-Jinhua pigs (YJ). We found that Y grow faster than J and YJ, while fatness-related characteristics observed in Y were lower than those of J and YJ. Besides, total mRNA m 5 C levels and expression rates of NSUN2 were higher both in backfat layer (BL) and longissimus dorsi muscle (LDM) of Y compared to J and YJ, suggesting that higher mRNA m 5 C levels positively correlate with lower fat and higher muscle mass. RNA bisulfite sequencing profiling of m 5 C revealed tissue-specific and dynamic features in pigs. Functionally, hyper-methylated m 5 C-containing genes were enriched in pathways linked to impaired adipogenesis and enhanced myogenesis. In in vitro, m 5 C inhibited lipid accumulation and promoted myogenic differentiation. Furthermore, YBX2 and SMO were identified as m 5 C targets. Mechanistically, YBX2 and SMO mRNAs with m 5 C modification were recognized and exported into the cytoplasm from the nucleus by ALYREF, thus leading to increased YBX2 and SMO protein expression and thereby inhibiting adipogenesis and promoting myogenesis, respectively. Our work uncovered the critical role of mRNA m 5 C in regulating adipogenesis and myogenesis via ALYREF-m 5 C-YBX2 and ALYREF-m 5 C-SMO manners, providing a potential therapeutic target in the prevention and treatment of obesity, skeletal muscle dysfunction and metabolic disorder diseases., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

5-Methylcytosine (m 5 C) is a type of RNA modification that exists in tRNAs and rRNAs and was recently found in mRNA. Although mRNA m 5 C modification has been reported to regulate diverse biological process, its function in adipogenesis remains unknown. Here, we demonstrated that knockdown of NOL1/NOP2/Sun domain family member 2 (NSUN2), a m 5 C methyltransferase, increased lipid accumulation of 3T3-L1 preadipocytes through accelerating cell cycle progression during mitotic clonal expansion (MCE) at the early stage of adipogenesis. Mechanistically, we proved that NSUN2 directly targeted cyclin-dependent kinase inhibitor 1A ( CDKN1A ) mRNA, a key inhibitory regulator of cell cycle progression, and upregulated its protein expression in an m 5 C-dependent manner. Further study identified that CDKN1A was the target of Aly/REF export factor (ALYREF), a reader of m 5 C modified mRNA. Upon NSUN2 deficiency, the recognition of CDKN1A mRNA by ALYREF was suppressed, resulting in the decrease of CDKN1A mRNA shuttling from nucleus to cytoplasm. Thereby, the translation of CDKN1A was reduced, leading to the acceleration of cell cycle and the promotion of adipogenesis. Together, these findings unveiled an important function and mechanism of the m 5 C modification on adipogenesis by controlling cell cycle progression, providing a potential therapeutic target to prevent obesity.

Obesity, defined as excessive fat accumulation, is strongly associated with metabolic diseases and cancer, and its prevalence is rising worldwide. Thus, understanding the molecular mechanism of adipogenesis is of fundamental significance. Epigenetic modifications play important roles in regulating adipogenesis. N 6 -methyladenosine (m 6 A), the most prevalent and abundant mRNA modification in eukaryotic cells, modulates multiple aspects of RNA metabolism, including mRNA stability, translation, splicing and export. Recent studies indicate that m 6 A methylation plays important roles in modulating gene expression and signal pathways in various physiologic processes and diseases. Notably, the significant function and regulatory mechanisms of m 6 A in adipogenesis are now emerging. In this review, we summarize recent studies that elucidate the vital roles of m 6 A modifications in regulating adipogenesis and adipose tissue expansion. Furthermore, we highlight the nutritional regulation of m 6 A methylation and adipogenesis, which may prove a novel therapeutic strategy to fight against obesity., (©2020 World Obesity Federation.)

N: 6 -methyladenosine (m 6 A), the most abundant internal modification on mRNAs in eukaryotes, play roles in adipogenesis. However, the underlying mechanism remains largely unclear. Here, we show that m 6 A plays a critical role in regulating macroautophagy/autophagy and adipogenesis through targeting Atg5 and Atg7 . Mechanistically, knockdown of FTO, a well-known m 6 A demethylase, decreased the expression of ATG5 and ATG7, leading to attenuation of autophagosome formation, thereby inhibiting autophagy and adipogenesis. We proved that FTO directly targeted Atg5 and Atg7 transcripts and mediated their expression in an m 6 A-dependent manner. Further study identified that Atg5 and Atg7 were the targets of YTHDF2 (YTH N6-methyladenosine RNA binding protein 2). Upon FTO silencing, Atg5 and Atg7 transcripts with higher m 6 A levels were captured by YTHDF2, which resulted in mRNA degradation and reduction of protein expression, thus alleviating autophagy and adipogenesis. Furthermore, we generated an adipose-selective fto knockout mouse and find that FTO deficiency decreased white fat mass and impairs ATG5- and ATG7-dependent autophagy in vivo . Together, these findings unveil the functional importance of the m 6 A methylation machinery in autophagy and adipogenesis regulation, which expands our understanding of such interplay that is essential for development of therapeutic strategies in the prevention and treatment of obesity., Abbreviations: 3-MA: 3-methyladenine; ACTB: actin, beta; ATG: autophagy-related; Baf A1: bafilomycin A 1 ; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; CEBPB: CCAAT/enhancer binding protein (C/EBP), beta; FABP4: fatty acid binding protein 4, adipocyte; FTO: fat mass and obesity associated; HFD: high-fat diet; LC-MS/MS: liquid chromatography-tandem mass spectrometry; MAP1LC3B/LC3: microtubule-associated protein 1 light chain 3 beta; m 6 A: N 6 -methyladenosine; MEFs: mouse embryo fibroblasts; MeRIP-qPCR: methylated RNA immunoprecipitation-qPCR; PPARG: peroxisome proliferator activated receptor gamma; RIP: RNA-immunoprecipitation; SAT: subcutaneous adipose tissue; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; ULK1: unc-51 like kinase 1; VAT: visceral adipose tissue; WAT: white adipose tissue; YTHDF: YTH N6-methyladenosine RNA binding protein.

Obesity is becoming a global problem. Research into the detailed mechanism of adipocyte development is crucial for the treatment of excess fat. Zinc finger protein 217 plays roles in adipogenesis. However, the underlying mechanism remains unclear. Here, we demonstrated that ZFP217 knockdown prevented the mitotic clonal expansion process and caused adipogenesis inhibition. Depletion of ZFP217 increased the expression of the m 6 A methyltransferase METTL3, which upregulated the m 6 A level of cyclin D1 mRNA. METTL3 knockdown rescued the siZFP217-inhibited MCE and promoted CCND1 expression. YTH domain family 2 recognized and degraded the methylated CCND1 mRNA, leading to the downregulation of CCND1. Consequently, cell-cycle progression was blocked, and adipogenesis was inhibited. YTHDF2 knockdown relieved siZFP217-inhibited adipocyte differentiation. These findings reveal that ZFP217 knockdown-induced adipogenesis inhibition was caused by CCND1, which was mediated by METTL3 and YTHDF2 in an m 6 A-dependent manner. We have provided novel insight into the underlying molecular mechanisms by which m 6 A methylation is involved in the ZFP217 regulation of adipogenesis.

Family with Sequence Similarity 134, Member B (FAM134B) is a protein that known to be necessary for the long-term survival of nociceptive and autonomic ganglion neurons. Recent work has exhibited that FAM134B plays a pivotal role in autophagy-mediated turnover of endoplasmic reticulum (ER) membranes, tumor inhibition and lipid homeostasis. In this study, we provide mechanistic links between FAM134B and adipocyte differentiation. Here, we found that adipocyte-specific FAM134B overexpression mice are obese and have increased white adipose tissue (WAT) mass. Serum tests showed that they developed high glucose level and severe insulin resistance. In addition, they also exhibited enhanced autophagy and reduced mitochondria amount, suggesting the function of FAM134B to promote autophagy in adipocytes. Overexpression of FAM134B in 3 T3-L1 preadipocytes promoted autophagy and differentiation, while the effect could be inhibited after treatment with autophagyinhibitors, 3-methyladenine (3-MA). Overexpressioncells also showed an early reduction of mitochondria number, while its autophagy flux level increased fast from differentiation day 2. These findings indicate that FAM134B improves adipocytes differentiation through enhancing mitophagy., (Copyright © 2019 Elsevier B.V. All rights reserved.)

N 6 -methyladenosine (m 6 A), the most abundant internal mRNA modification in eukaryotes, plays a vital role in regulating adipogenesis. However, its underlying mechanism remains largely unknown. Here, we reveal that deletion of m 6 A demethylase FTO in porcine and mouse preadipocytes inhibits adipogenesis through JAK2-STAT3-C/EBPβ signaling. Mechanistically, FTO deficiency suppresses JAK2 expression and STAT3 phosphorylation, leading to attenuated transcription of C/EBPβ, which is essential for the early stage of adipocyte differentiation. Using dual-luciferase assay, we validate that knockdown of FTO reduces expression of JAK2 in an m 6 A-dependent manner. Furthermore, we find that m 6 A "reader" protein YTHDF2 directly targets m 6 A-modified transcripts of JAK2 and accelerates mRNA decay, which results in decreased JAK2 expression and inactivated JAK2-STAT3-C/EBPβ signaling, thereby inhibiting adipogenesis. Collectively, our results provide a novel insight into the molecular mechanism of m 6 A methylation in post-transcriptional regulation of JAK2-STAT3-C/EBPβ signaling axis and highlight the crucial role of m 6 A modification and its modulators in adipogenesis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

N 6 -methyladenosine (m 6 A) mRNA modification plays an important role in adipogenesis, but its role on single gene remains unexplored. Family with Sequence Similarity 134, Member B (FAM134B) is a cis-Golgi transmembrane protein that known to be necessary for the long-term survival of nociceptive and autonomic ganglion neurons. Recent work has shown that FAM134B plays a pivotal role in lipid homeostasis and was identified as its significant m 6 A level difference between Chinese local Jinhua pigs and Landrace through RNA-sequence. Here, we construct the non-m 6 A FAM134B coding sequence (CDS) plasmid (FAM134B-MUT) and found one important m 6 A site on its CDS. Expression of FAM134B-MUT was more effective in promoting porcine preadipocytes adipogenic differentiation and lipid deposition than wild-type FAM134B (FAM134B-WT) both in early and ultimate differentiation stage. FAM134B-MUT functions better in promoting fat deposition by upregulating peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein (C/EBPα) level. The m 6 A reader protein YTH m 6 A RNA binding protein 2 (YTHDF2) interacts with FAM134B mRNA and down regulated its protein level. These results demonstrate that FAM134B was the target of YTHDF2, which may recognize and binds the m 6 A site of FAM134B to reduce its mRNA lifetime and reduce its protein abundance. © 2018 IUBMB Life, 71(5):580-586, 2019., (© 2018 International Union of Biochemistry and Molecular Biology.)

Family with sequence similarity 134, Member B (FAM134B), is a cis-Golgi transmembrane protein that is known to be necessary for the long-term survival of nociceptive and autonomic ganglion neurons. Recent work has shown that FAM134B plays a pivotal role in autophagy-mediated turnover of endoplasmic reticulum (ER) membranes, tumor inhibition and lipid homeostasis. In this study, we provide mechanistic links between FAM134B and ARF-related protein 1 (ARFRP1) and further show that FAM134B resides in the Golgi apparatus. Here, we found that FAM134B increased lipid accumulation in adipocytes. Transport vehicle number and ADP-ribosylation factor (ARF) family gene expression were also increased by FAM134B overexpression, suggesting that vesicular transport activity enhanced lipid accumulation. ARF-related protein 1 (ARFRP1) is a GTPase that promotes protein trafficking. We show that FAM134B regulates the expression of ARFRP1, and the knockdown of ARFRP1 abolishes enhancement on lipid accumulation caused by FAM134B. In addition, FAM134B upregulates the PAT family protein (PAT), which associates with the lipid droplets (LDs) surface and promotes lipolysis by recruiting adipocyte triglyceride lipase (ATGL). These findings indicate that FAM134B promotes lipid accumulation and adipogenic differentiation by increasing vesicle transport activity in the Golgi apparatus and inhibiting the lipolysis of LDs.

Intramuscular fat is considered a potential factor that is associated with meat quality in animal production and insulin resistance in humans. N 6 -methyladenosine (m 6 A) modification of mRNA plays an important role in regulating adipogenesis. However, the effects of m 6 A on the adipogenesis of intramuscular preadipocytes and associated mechanisms remain unknown. Here, we performed m 6 A sequencing to compare m 6 A methylome of the longissimus dorsi muscles (LDMs) between Landrace pigs (lean-type breed) and Jinhua pigs (obese-type breed with higher levels of intramuscular fat). Transcriptome-wide m 6 A profiling of porcine LDMs was highly conserved with humans and mice. Furthermore, we identified a unique methylated gene in Jinhua pigs named mitochondrial carrier homology 2 ( MTCH2). The m 6 A levels of MTCH2 mRNA were reduced by introducing a synonymous mutation, and adipogenesis test results showed that the MTCH2 mutant was inferior with regard to adipogenesis compared with the MTCH2 wild-type. We then found that MTCH2 protein expression was positively associated with m 6 A levels, and an YTH domain family protein 1-RNA immunoprecipitation-quantitative PCR assay indicated that MTCH2 mRNA was a target of the YTH domain family protein 1. This study provides comprehensive m 6 A profiles of LDM transcriptomes in pigs and suggests an essential role for m 6 A modification of MTCH2 in intramuscular fat regulation.-Jiang, Q., Sun, B., Liu, Q., Cai, M., Wu, R., Wang, F., Yao, Y., Wang, Y., Wang, X. MTCH2 promotes adipogenesis in intramuscular preadipocytes via an m 6 A-YTHDF1-dependent mechanism.

N 6 -methyladenosine (m 6 A) is the most prevalent internal mRNA modification in eukaryotes. Loss of m 6 A demethylase FTO increases m 6 A levels and inhibits adipogenesis of preadipocytes. However, its underlying mechanism remains elusive. Here, we demonstrated that silencing FTO inhibited adipogenesis of preadipocytes through impairing cell cycle progression at the early stage of adipogenesis. FTO knockdown markedly decreased the expression of CCNA2 and CDK2, crucial cell cycle regulators, leading to delayed entry of MDI-induced cells into G2 phase. Furthermore, the m 6 A levels of CCNA2 and CDK2 mRNA were significantly upregulated following FTO knockdown. m 6 A-binding protein YTHDF2 recognized and decayed methylated mRNAs of CCNA2 and CDK2, leading to decreased protein expression, thereby prolonging cell cycle progression and suppressing adipogenesis. Our work unravels that FTO regulates adipogenesis by controlling cell cycle progression in an m 6 A-YTHDF2 dependent manner, which provides insights into critical roles of m 6 A methylation in adipogenesis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Betaine, a neutral zwitterionic compound, could regulate intramuscular fat (IMF) deposition and meat quality. However, the efficacy is controversial. Moreover, the regulatory mechanism of betaine on lipid metabolism in skeletal muscle cells remains unclear. Therefore, in this study, we examined the effects and regulatory mechanism of betaine on lipid accumulation in adipogenic-differentiated C2C12 cells. We found that adipogenic-induced C2C12 cells treated with 10 mM betaine for 24 and 48 h had more lipid accumulation than the control group. Real-time PCR and Western blot results revealed that betaine treatment did not alter the expression of lipolysis and lipid oxidation-related genes, but dramatically increased the expression of peroxisome proliferator-activated receptor γ (PPARγ) and its target genes such as fatty acid binding protein 4 (aP2), fatty acid synthase (FAS) and lipoprteinlipase (LPL). Furthermore, betaine combined with PPARγ inhibitor GW9662 treatment showed that betaine elevated C2C12 lipid accumulation through upregulation of PPARγ. Mechanistically, we found that betaine promoted PPARγ expression and lipid accumulation through inhibition of extracellular regulated protein kinases1/2 (ERK1/2) signalling pathway. These results demonstrate that betaine acts through ERK1/2-PPARγ signalling pathway to regulate lipid metabolism in adipogenic-differentiated skeletal muscle cells, which could provide some useful information for controlling muscle lipid accumulation by manipulating ERK1/2 and PPARγ signalling pathway.

Background/objective: N 6 -methyladenosine (m 6 A) modification of mRNA plays a role in regulating adipogenesis. However, its underlying mechanism remains largely unknown. Epigallocatechin gallate (EGCG), the most abundant catechin in green tea, plays a critical role in anti-obesity and anti-adipogenesis., Methods: High-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (HPLC-QqQ-MS/MS) was performed to determine the m 6 A levels in 3T3-L1 preadipocytes. The effects of EGCG on the m 6 A levels in specific genes were determined by methylated RNA immunoprecipitation coupled with quantitative real-time PCR (meRIP-qPCR). Several adipogenesis makers and cell cycle genes were analyzed by quantitative real-time PCR (qPCR) and western blotting. Lipid accumulation was evaluated by oil red O staining. All measurements were performed at least for three times., Results: Here we showed that EGCG inhibited adipogenesis by blocking the mitotic clonal expansion (MCE) at the early stage of adipocyte differentiation. Exposing 3T3-L1 cells to EGCG reduced the expression of fat mass and obesity-associated (FTO) protein, an m 6 A demethylase, which led to increased overall levels of RNA m 6 A methylation. Cyclin A2 (CCNA2) and cyclin dependent kinase 2 (CDK2) play vital roles in MCE. The m 6 A levels of CCNA2 and CDK2 mRNA were dramatically enhanced by EGCG. Interestingly, EGCG increased the expression of YTH N 6 -methyladenosine RNA binding protein 2 (YTHDF2), which recognized and decayed methylated mRNAs, resulting in decreased protein levels of CCNA2 and CDK2. As a result, MCE was blocked and adipogenesis was inhibited. FTO overexpression and YTHDF2 knockdown in 3T3-L1 cells significantly increased CCNA2 and CDK2 protein levels and ameliorated the EGCG-induced adipogenesis inhibition. Thus, m 6 A-dependent CCNA2 and CDK2 expressions mediated by FTO and YTHDF2 contributed to EGCG-induced adipogenesis inhibition., Conclusion: Our findings provide mechanistic insights into how m 6 A is involved in the EGCG regulation of adipogenesis and shed light on its anti-obesity effect.

New fat cells originate from a preexisting population of undifferentiated progenitor cells named preadipocytes. The process in which preadipocytes proliferate and differentiate into mature adipocytes under certain circumstances is called adipogenesis. In the past decade, many epigenetic factors have been shown to be pivotal for the appropriate timing of adipogenesis. A large number of coregulators at critical gene promoters set up specific patterns of DNA methylation, histone methylation and RNA methylation, which act as an epigenetic code to modulate the correct progress of adipocyte differentiation and adipogenesis. In this review, we focus on the functions and roles of epigenetic processes in preadipocyte differentiation and adipogenesis., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Fat Mass and Obesity-associated protein (FTO), associated with obesity, is proved to demethylate N6-methyladenosine (m(6)A), which raises questions regarding whether m(6)A plays vital roles in adipogenesis. To prove this, overexpression and knockdown of FTO and METTL3, as well as the chemical treatment in procine adipocytes were conducted. The results showed FTO negatively regulated m(6)A levels and positively regulated adipogenesis, while METTL3 positively correlated with m(6)A levels and negatively with adipogenesis. To remove the potential effect of FTO and METTL3 gene, chemical reagents of methylation inhibitor cycloleucine and methyl donor betaine were used to test the regulation effect of m(6)A on adipogenesis. The results showed the inverse effect of m(6)A on lipid accumulation in porcine adipocytes. These findings provide compelling evidence that m(6)A plays a critical role in the regulation of adipogenesis., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: Intramuscular fat (IMF) content is a critical indicator of pork quality, and abnormal IMF is also relevant to human disease as well as aging. Although N6-methyladenosine (m6A) RNA modification was recently found to regulate adipogenesis in porcine intramuscular fat, however, the underlying molecular mechanisms was still unclear. Results: In this work, we collected 20 longissimus dorsi muscle samples with high (average 3.95%) or low IMF content (average 1.22%) from a unique heterogenous swine population for m6A sequencing (m6A-seq). We discovered 70 genes show both differential RNA expression and m6A modification from high and low IMF group, including ADIPOQ and SFRP1, two hub genes inferred through gene co-expression analysis. Particularly, we observed ADIPOQ, which contains three m6A modification sites within 3′ untranslated and protein coding region, could promote porcine intramuscular preadipocyte differentiation in an m6A-dependent manner. Furthermore, we found the YT521‑B homology domain family protein 1 (YTHDF1) could target and promote ADIPOQ mRNA translation. Conclusions: Our study provided a comprehensive profiling of m6A methylation in porcine longissimus dorsi muscle and characterized the involvement of m6A epigenetic modification in the regulation of ADIPOQ mRNA on IMF deposition through an m6A-YTHDF1-dependent manner. [ABSTRACT FROM AUTHOR]

Obesity has become a health threat and hard enough to deal with. Evidences show that metformin could inhibit adipogenesis and combat obesity, while its mechanisms remain to be elucidated more comprehensively. In this study, we found that administration of metformin could combat obesity of mice induced by high-fat diet (HFD), indicated by strikingly decreased body weight and weight of inguinal white adipose tissue (iWAT) and epidydimal white adipose tissue (eWAT) compared with the control group. Mechanically, we revealed that metformin could inhibit protein expression of FTO, leading to increased m6A methylation levels of cyclin D1 (Ccnd1) and cyclin dependent kinase 2 (Cdk2), two crucial regulators in cell cycle. Ccnd1 and Cdk2 with increased m6A levels were recognised by YTH m6A RNA binding protein 2 (YTHDF2), causing an YTHDF2-dependent decay and decreased protein expressions. In consequence, mitotic clonal expansion (MCE) process was blocked and adipogenesis was inhibited. [ABSTRACT FROM AUTHOR]

Obesity has become a major health problem that has rapidly prevailed over the past several decades worldwide. Curcumin, a natural polyphenolic compound present in turmeric, has been shown to have a protective effect on against obesity and metabolic diseases. However, its underlying mechanism remains largely unknown. Here, we show that the administration of curcumin significantly prevents HFD‐induced obesity and decreases the fat mass of the subcutaneous inguinal WAT (iWAT) and visceral epididymal WAT (eWAT) in mice. Mechanistically, curcumin inhibits adipogenesis by reducing the expression of AlkB homolog 5 (ALKHB5), an m6A demethylase, which leads to higher m6A‐modified TNF receptor‐associated factor 4 (TRAF4) mRNA. TRAF4 mRNA with higher m6A level is recognized and bound by YTHDF1, leading to enhanced translation of TRAF4. TRAF4, acting as an E3 RING ubiquitin ligase, promotes degradation of adipocyte differentiation regulator PPARγ by a ubiquitin–proteasome pathway thereby inhibiting adipogenesis. Thus, m6A‐dependent TRAF4 expression upregulation by ALKBH5 and YTHDF1 contributes to curcumin‐induced obesity prevention. Our findings provide mechanistic insights into how m6A is involved in the anti‐obesity effect of curcumin. SYNOPSIS: Curcumin exerts its anti‐obesity effect by increasing the ALKBH5‐mediated m6A modification of TRAF4 mRNA, and enhancing TRAF4 translation in an YTHDF1‐dependent manner. TRAF4 in turn promotes ubiquitination of PPARγ and inhibits adipogenesis. Curcumin feeding prevents HFD‐induced obesity and metabolic dysfunction in mice.Curcumin feeding increases m6A modified RNA levels in iWAT and eWAT and decreases ALKBH5 levels in mice.Decreased ALKBH5 protein results in higher m6A modification of TRAF4 mRNA, which is recognized and bound by YTHDF1, leading to enhanced translation of TRAF4 in adipocytes.TRAF4, acting as an E3 RING ubiquitin ligase, promotes ubiquitination of PPARγ, leading to lower PPARγ level and inhibits adipogenesis in adipocytes. [ABSTRACT FROM AUTHOR]

Summary: Obesity, defined as excessive fat accumulation, is strongly associated with metabolic diseases and cancer, and its prevalence is rising worldwide. Thus, understanding the molecular mechanism of adipogenesis is of fundamental significance. Epigenetic modifications play important roles in regulating adipogenesis. N6‐methyladenosine (m6A), the most prevalent and abundant mRNA modification in eukaryotic cells, modulates multiple aspects of RNA metabolism, including mRNA stability, translation, splicing and export. Recent studies indicate that m6A methylation plays important roles in modulating gene expression and signal pathways in various physiologic processes and diseases. Notably, the significant function and regulatory mechanisms of m6A in adipogenesis are now emerging. In this review, we summarize recent studies that elucidate the vital roles of m6A modifications in regulating adipogenesis and adipose tissue expansion. Furthermore, we highlight the nutritional regulation of m6A methylation and adipogenesis, which may prove a novel therapeutic strategy to fight against obesity. [ABSTRACT FROM AUTHOR]

6-methyladenosine (m6A), the most abundant internal modification on mRNAs in eukaryotes, play roles in adipogenesis. However, the underlying mechanism remains largely unclear. Here, we show that m6A plays a critical role in regulating macroautophagy/autophagy and adipogenesis through targeting Atg5 and Atg7. Mechanistically, knockdown of FTO, a well-known m6A demethylase, decreased the expression of ATG5 and ATG7, leading to attenuation of autophagosome formation, thereby inhibiting autophagy and adipogenesis. We proved that FTO directly targeted Atg5 and Atg7 transcripts and mediated their expression in an m6A-dependent manner. Further study identified that Atg5 and Atg7 were the targets of YTHDF2 (YTH N6-methyladenosine RNA binding protein 2). Upon FTO silencing, Atg5 and Atg7 transcripts with higher m6A levels were captured by YTHDF2, which resulted in mRNA degradation and reduction of protein expression, thus alleviating autophagy and adipogenesis. Furthermore, we generated an adipose-selective fto knockout mouse and find that FTO deficiency decreased white fat mass and impairs ATG5- and ATG7-dependent autophagy in vivo. Together, these findings unveil the functional importance of the m6A methylation machinery in autophagy and adipogenesis regulation, which expands our understanding of such interplay that is essential for development of therapeutic strategies in the prevention and treatment of obesity. 3-MA: 3-methyladenine; ACTB: actin, beta; ATG: autophagy-related; Baf A1: bafilomycin A1; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; CEBPB: CCAAT/enhancer binding protein (C/EBP), beta; FABP4: fatty acid binding protein 4, adipocyte; FTO: fat mass and obesity associated; HFD: high-fat diet; LC-MS/MS: liquid chromatography-tandem mass spectrometry; MAP1LC3B/LC3: microtubule-associated protein 1 light chain 3 beta; m6A: N6-methyladenosine; MEFs: mouse embryo fibroblasts; MeRIP-qPCR: methylated RNA immunoprecipitation-qPCR; PPARG: peroxisome proliferator activated receptor gamma; RIP: RNA-immunoprecipitation; SAT: subcutaneous adipose tissue; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; ULK1: unc-51 like kinase 1; VAT: visceral adipose tissue; WAT: white adipose tissue; YTHDF: YTH N6-methyladenosine RNA binding protein [ABSTRACT FROM AUTHOR]

Obesity is becoming a global problem. Research into the detailed mechanism of adipocyte development is crucial for the treatment of excess fat. Zinc finger protein 217 plays roles in adipogenesis. However, the underlying mechanism remains unclear. Here, we demonstrated that ZFP217 knockdown prevented the mitotic clonal expansion process and caused adipogenesis inhibition. Depletion of ZFP217 increased the expression of the m6A methyltransferase METTL3, which upregulated the m6A level of cyclin D1 mRNA. METTL3 knockdown rescued the siZFP217-inhibited MCE and promoted CCND1 expression. YTH domain family 2 recognized and degraded the methylated CCND1 mRNA, leading to the downregulation of CCND1. Consequently, cell-cycle progression was blocked, and adipogenesis was inhibited. YTHDF2 knockdown relieved siZFP217-inhibited adipocyte differentiation. These findings reveal that ZFP217 knockdown–induced adipogenesis inhibition was caused by CCND1, which was mediated by METTL3 and YTHDF2 in an m6A-dependent manner. We have provided novel insight into the underlying molecular mechanisms by which m6A methylation is involved in the ZFP217 regulation of adipogenesis. [ABSTRACT FROM AUTHOR]

N 6-methyladenosine (m6A), the most abundant internal mRNA modification in eukaryotes, plays a vital role in regulating adipogenesis. However, its underlying mechanism remains largely unknown. Here, we reveal that deletion of m6A demethylase FTO in porcine and mouse preadipocytes inhibits adipogenesis through JAK2-STAT3-C/EBPβ signaling. Mechanistically, FTO deficiency suppresses JAK2 expression and STAT3 phosphorylation, leading to attenuated transcription of C/EBPβ, which is essential for the early stage of adipocyte differentiation. Using dual-luciferase assay, we validate that knockdown of FTO reduces expression of JAK2 in an m6A-dependent manner. Furthermore, we find that m6A "reader" protein YTHDF2 directly targets m6A-modified transcripts of JAK2 and accelerates mRNA decay, which results in decreased JAK2 expression and inactivated JAK2-STAT3-C/EBPβ signaling, thereby inhibiting adipogenesis. Collectively, our results provide a novel insight into the molecular mechanism of m6A methylation in post-transcriptional regulation of JAK2-STAT3-C/EBPβ signaling axis and highlight the crucial role of m6A modification and its modulators in adipogenesis. • FTO promotes adipogenesis through activating JAK2-STAT3-C/EBPβ pathway. • FTO enhances JAK2 expression by decreasing its m6A mRNA modification. • YTHDF2 destabilizes JAK2 mRNA in a m6A-dependent manner. • The m6A modification and its modulators play a critical role in regulation of early adipogenesis. [ABSTRACT FROM AUTHOR]

N6‐methyladenosine (m6A) mRNA modification plays an important role in adipogenesis, but its role on single gene remains unexplored. Family with Sequence Similarity 134, Member B (FAM134B) is a cis‐Golgi transmembrane protein that known to be necessary for the long‐term survival of nociceptive and autonomic ganglion neurons. Recent work has shown that FAM134B plays a pivotal role in lipid homeostasis and was identified as its significant m6A level difference between Chinese local Jinhua pigs and Landrace through RNA‐sequence. Here, we construct the non‐m6A FAM134B coding sequence (CDS) plasmid (FAM134B‐MUT) and found one important m6A site on its CDS. Expression of FAM134B‐MUT was more effective in promoting porcine preadipocytes adipogenic differentiation and lipid deposition than wild‐type FAM134B (FAM134B‐WT) both in early and ultimate differentiation stage. FAM134B‐MUT functions better in promoting fat deposition by upregulating peroxisome proliferator‐activated receptor γ (PPARγ) and CCAAT/enhancer‐binding protein (C/EBPα) level. The m6A reader protein YTH m6A RNA binding protein 2 (YTHDF2) interacts with FAM134B mRNA and down regulated its protein level. These results demonstrate that FAM134B was the target of YTHDF2, which may recognize and binds the m6A site of FAM134B to reduce its mRNA lifetime and reduce its protein abundance. © 2018 IUBMB Life, 71(5):580–586, 2019 [ABSTRACT FROM AUTHOR]

Adipocytes play a central role in overall energy homeostasis and are important contributors to the immune system. Fatty acids (FAs) act as signaling molecules capable to modulate adipocyte metabolism and functions. To identify the effects of two commonly used FAs in Atlantic salmon diets, primary adipocytes were cultured in the presence of oleic (OA) or docosahexaenoic (DHA) acid. DHA decreased adipocyte lipid droplet number and area compared to OA. The increase in lipid load in OA treated adipocytes was paralleled by an increase in iNOS activity and mitochondrial SOD2-GFP activity, which was probably directed to counteract increase in oxidative stress. Under lipopolysaccharide (LPS)-induced inflammation, DHA had a greater anti-inflammatory effect than OA, as evidenced by the higher SOD2 activity and the transcriptional regulation of antioxidant enzymes and pro- and anti-inflammatory markers. In addition, DHA maintained a healthy mitochondrial structure under induced inflammation while OA led to elongated mitochondria with a thin thread like structures in adipocytes exposed to LPS. Overall, DHA possess anti-inflammatory properties and protects Atlantic salmon against oxidative stress and limits lipid deposition. Furthermore, DHA plays a key role in protecting mitochondria shape and function. [ABSTRACT FROM AUTHOR]

Obesity has become a major health crisis in the past decades. Branched-chain amino acids (BCAA), a class of essential amino acids, exerted beneficial health effects with regard to obesity and its related metabolic dysfunction, although the underlying reason is unknown. Here, we show that BCAA supplementation alleviates high-fat diet (HFD)-induced obesity and insulin resistance in mice and inhibits adipogenesis in 3T3-L1 cells. Further, we find that BCAA prevent the mitotic clonal expansion (MCE) of preadipocytes by reducing cyclin A2 (CCNA2) and cyclin-dependent kinase 2 (CDK2) expression. Mechanistically, BCAA decrease the concentration of nicotinamide adenine dinucleotide phosphate (NADPH) in adipose tissue and 3T3-L1 cells by reducing glucose-6-phosphate dehydrogenase (G6PD) expression. The reduced NADPH attenuates the expression of fat mass and obesity-associated (FTO) protein, a well-known m6A demethylase, to increase the N 6-methyladenosine (m6A) levels of Ccna2 and Cdk2 mRNA. Meanwhile, the high m6A levels of Ccna2 and Cdk2 mRNA are recognized by YTH N 6-methyladenosine RNA binding protein 2 (YTHDF2), which results in mRNA decay and reduction of their protein expressions. Overall, our data demonstrate that BCAA inhibit obesity and adipogenesis by reducing CDK2 and CCNA2 expression via an NADPH-FTO-m6A coordinated manner in vivo and in vitro , which raises a new perspective on the role of m6A in the BCAA regulation of obesity and adipogenesis. [Display omitted] [ABSTRACT FROM AUTHOR]