miR-34a regulates adipogenesis in porcine intramuscular adipocytes by targeting ACSL4

Profiling and functional analysis of circular RNAs in yaks intramuscular fat

Circular RNAs (circRNAs) are a new class of endogenous RNA regulating gene expression. However, the regulatory mechanisms of lipid metabolism in yaks involved in circRNAs remain poorly understood. The IMF plays a crucial role in the quality of yak meat, to greatly improve the meat quality. In this study, the fatty acid profiles of yak IMF were determined and circRNAs were sequenced. The results showed that the total of polyunsaturated fatty acid (PUFA) content of adult yak muscle was significantly higher than that in yak calves (p < 0.05). A total of 29,021 circRNAs were identified in IMF tissue, notably, 99 differentially expressed (DE) circRNAs were identified, to be associated with fat deposition, the most significant of which were circ_12686, circ_6918, circ_3582, ci_106 and ci_123 (A circRNA composed of exons is labelled 'circRNA' and a circRNA composed of introns is labelled 'ciRNA'). KEGG pathway enrichment analysis showed that the differential circRNAs were enriched in four pathways associated with fat deposition (e.g., the peroxisome proliferator-activated receptor signalling, fatty acid degradation, sphingolipid metabolism and sphingolipid signalling pathways). We also constructed co-expression networks of DE circRNA-miRNA using high-throughput sequencing in IMF deposition, from which revealed that ci_106 target binding of bta-miR-130b, bta-miR-148a, bta-miR-15a, bta-miR-34a, bta-miR-130a, bta-miR-17-5p and ci_123 target binding of bta-miR-150 were involved in adipogenesis. The study revealed the role of the circRNAs in the IMF deposition in yak and its influence on meat quality the findings demonstrated the circRNA differences in the development of IMF with the increase of age, thus providing a theoretical basis for further research on the molecular mechanism of IMF deposition in yaks.

Chaihu Shugan powder influences nonalcoholic fatty liver disease in rats in remodeling microRNAome and decreasing fatty acid synthesis

ETHNOPHARMACOLOGICAL RELEVANCE

Chaihu Shugan powder (CSP) plays an important role in the prevention and treatment of nonalcoholic fatty liver disease (NAFLD) through a variety of biological mechanisms. However, whether the mechanism involves microRNA (miRNA) regulation remains unknown.

AIM OF THE STUDY

To investigate the effects of CSP on the miRNA expression profile of rats with NAFLD induced by high-fat diet (HFD), and to explore the mechanism of CSP in the treatment of NAFLD.

METHODS

NAFLD rat models were established by an 8-week HFD. The therapeutic effects of CSP on NAFLD were evaluated by physiological, biochemical and pathological analysis and hepatic surface microcirculation perfusion test. MicroRNA sequencing was used to study the effect of CSP on the miRNA expression profile of NAFLD rats, and the target genes of differentially expressed (DE) miRNAs were predicted for further function enrichment analysis. Next, targets of CSP and NAFLD were collected by a network pharmacological approach, and Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis were performed for the common target genes of CSP, NAFLD and DE miRNAs, and the expression levels of key genes and proteins were verified by quantitative Real-time PCR and Western blot. Finally, a network among formula-herb-compound-miRNA-target-biological processes-disease was established to explained the complex regulation mechanism of CSP on NAFLD.

RESULTS

The results showed that CSP significantly improved liver lipid accumulation, serum lipid and transaminase levels and liver surface microcirculation disturbance in HFD-induced NAFLD rats. The intervention of CSP reversed the high expression of 15 miRNAs in liver tissues induced by HFD, including miR-34a-5p, miR-146a-5p, miR-20b-5p and miR-142-3p. The results of pathway and functional enrichment analysis showed that, CSP might play an anti-NAFLD role via regulating DE miRNAs related to fatty acid metabolic process. Combined with the network pharmacological analysis, it was found that the DE miRNAs might affected the fatty acid biosynthesis pathway in the treatment of NAFLD by CSP. Molecular biology experiments have conformed the decreased the gene and protein levels of acetyl-CoA carboxylase alpha (ACACA), fatty acid synthase (FASN) and other fatty acid biosynthesis related enzymes on NAFLD rats after intervention of CSP.

CONCLUSIONS

CSP can significantly reduce hepatic lipid accumulation of NAFLD rat model induced by HFD, and its mechanism may be through the action of 15 miRNAs such as miR-34a-5p, miR-146a-5p, miR-20b-5p and miR-142-3p. Reduce the gene and protein expression levels of ACACA, FASN and other fatty acid biosynthesis related enzymes, thus reducing fatty acid biosynthesis. Based on an epigenetic perspective, this study explains the key anti-NAFLD mechanism of CSP via combination of microRNA sequencing and network pharmacological analysis, providing a new reference for the modernization of traditional Chinese medicine.

SIRT1/SREBPs-mediated regulation of lipid metabolism

Sirtuins, also called silent information regulator 2, are enzymes that rely on nicotinamide adenine dinucleotide (NAD+) to function as histone deacetylases. Further investigation is warranted to explore the advantageous impacts of Sirtuin 1 (SIRT1), a constituent of the sirtuin group, on lipid metabolism, in addition to its well-researched involvement in extending lifespan. The regulation of gene expression has been extensively linked to SIRT1. Sterol regulatory element-binding protein (SREBP) is a substrate of SIRT1 that has attracted significant interest due to its role in multiple cellular processes including cell cycle regulation, DNA damage repair, and metabolic functions. Hence, the objective of this analysis was to investigate and elucidate the correlation between SIRT1 and SREBPs, as well as assess the contribution of SIRT1/SREBPs in mitigating lipid metabolism dysfunction. The objective of this research was to investigate whether SIRT1 and SREBPs could be utilized as viable targets for therapeutic intervention in managing complications associated with diabetes.

The global perspective on peroxisome proliferator-activated receptor γ (PPARγ) in ectopic fat deposition: A review

Excessive expansion of adipocytes can have unhealthy consequences as excess free fatty acids enter other tissues and cause ectopic fat deposition by resynthesizing triglycerides. This lipid accumulation in various tissues is harmful and can increase the risk of related metabolic diseases such as type II diabetes, cardiovascular disease, and insulin resistance. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily that play a key role in energy metabolism as fatty acid metabolism sensors, and peroxisome proliferator-activated receptor γ (PPARγ) is the main subtype responsible for fat cell differentiation and adipogenesis. In this paper, we introduce the main structure and function of PPARγ and its regulatory role in the process of lipogenesis in the liver, kidney, skeletal muscle, and pancreas. This information can serve as a reference for further understanding the regulatory mechanisms and measures of the PPAR family in the process of ectopic fat deposition.

miR-26a-5p Regulates Adipocyte Differentiation via Directly Targeting ACSL3 in Adipocytes

Preadipocytes become mature adipocytes after proliferation and differentiation, and although many genes and microRNAs have been identified in intramuscular fat, their physiological function and regulatory mechanisms remain largely unexplored. miR-26a-5p has been reported to be related to fat deposition, but its effect on porcine preadipocyte differentiation has not been explored. In this study, bioinformatics analysis and luciferase reporter assay identified that miR-26a-5p binds to the 3'UTR of Acyl-CoA synthetase long-chain family member 3 (ACSL3) mRNA. The model for porcine intramuscular preadipocyte differentiation was established to explore the function of miR-6a-5p-ACSL3 on adipocyte differentiation. ACSL3 knockdown markedly reduced the triglycerides (TG) content of cells, as well as the mRNA levels of adipogenic marker genes (PPAR-γ and SREBP-1c). The number of lipid droplets in cells transfected with a miR-26a-5p mimic is significantly reduced, consistent with ACSL3 knockdown results, while the miR-26a-5p inhibitor resulted in opposite results. Taken together, miR-26a-5p is a repressor of porcine preadipocyte differentiation and plays a vital role in ACSL3-mediated adipogenesis.

Ferroptosis Plays a Role in Human Chondrocyte of Osteoarthritis Induced by IL-1β In Vitro

OBJECTIVE

Osteoarthritis (OA) is a common disease with complex and unclear pathogenesis. Ferroptosis is a new cell death mode, which is proved to be involved in different kinds of disease. We hypothesized that ferroptosis contributes to the progress of human OA.

DESIGN

Chondrocytes were extracted from waste cartilage of total knee arthroplasty, and stimulated with interleukin-1β (IL-1β). Then, we detected the morphology, proliferation, and viability, and levels of Fe3+, glutathione (GSH), reactive oxygen species (ROS), malondialdehyde (MDA), and 5 proteins related to ferroptosis with or without intervention of ferrostatin-1 (Fer-1). In addition, we compared the effect of Fer-1 and liproxstatin-1 (Lip-1) on ferroptosis and the protection of chondrocytes by detecting several markers of both ferroptosis and OA.

RESULTS

After stimulation of IL-1β, there were significant changes on the shape of chondrocyte, with lower viability and proliferation. There was accumulation of intracellular Fe3+, GSH, ROS, and MDA, with the changes of expression of 5 ferroptosis-related proteins. With the contribution of Fer-1, results above were reversed. Moreover, there was no significant difference in GPX4 and ACSL4 between Fer-1 and Lip-1 group. However, the expression of COLX, ADAMTS5, and MMP-13 are lower after the treatment of Fer-1 compared with Lip-1.

CONCLUSIONS

Ferroptosis plays an important role in human OA chondrocytes, which can be reversed by Fer-1, illustrating that inhibitor of ferroptosis may be a potential treatment of OA. Moreover, Lip-1 and Fer-1 can both alleviate the level of ferroptosis in OA chondrocytes, but Fer-1 had a more protective effect.

A long non-coding RNA lnc210 promotes adipogenic differentiation of buffalo intramuscular adipocytes

Intramuscular fat (IMF) content is one of the most significant factors influencing beef quality in terms of tenderness, flavor, and juiciness. Thus, internal factors affecting IMF deposition have received considerable attention for decades. In this study, we demonstrated a long non-coding RNA, lnc210, promoted adipogenic differentiation of buffalo intramuscular adipocytes. lnc210 was rich in adipose tissue and showed increased expression with the adipogenic differentiation of buffalo intramuscular adipocytes. lnc210 was mainly expressed in the nucleus of adipocytes. Full-length lnc210 was obtained by rapid amplification of cDNA ends technology. lnc210 overexpression promoted lipid accumulation by upregulating the mRNA expression of peroxisome proliferator-activated receptor gamma (PPARG) and CCAAT enhancer binding protein alpha (C/EBPα) in buffalo intramuscular adipocytes. These results provide a basis for an in-depth analysis of the role of lnc210 in accelerating IMF deposition in buffaloes.

Traumatic acid inhibits ACSL4 associated lipid accumulation in adipocytes to attenuate high-fat diet-induced obesity

Obesity is a major health concern that lacks effective intervention strategies. Traumatic acid (TA) is a potent wound-healing agent in plants, considered an antioxidant food ingredient. This study demonstrated that TA treatment significantly reduced lipid accumulation in human adipocytes and prevented high-fat diet induced obesity in zebrafish. Transcriptome sequencing revealed TA-activated fatty acid (FA) degradation and FA metabolism signaling pathways. Moreover, western blotting and quantitative polymerase chain reaction showed that TA inhibited the expression of long-chain acyl-CoA synthetase-4 (ACSL4). Overexpression of ACSL4 resulted in the reversal of TA beneficiary effects, indicating that the attenuated lipid accumulation of TA was regulated by ACSL4 expression. Limited proteolysis-mass spectrometry and microscale thermophoresis were then used to confirm hexokinase 2 (HK2) as a direct molecular target of TA. Thus, we demonstrated the molecular basis of TA in regulating lipid accumulation and gave the first evidence that TA may function through the HK2-ACSL4 axis.

Acyl-CoA synthase ACSL4: an essential target in ferroptosis and fatty acid metabolism

ABSTRACT

Long-chain acyl-coenzyme A (CoA) synthase 4 (ACSL4) is an enzyme that esterifies CoA into specific polyunsaturated fatty acids, such as arachidonic acid and adrenic acid. Based on accumulated evidence, the ACSL4-catalyzed biosynthesis of arachidonoyl-CoA contributes to the execution of ferroptosis by triggering phospholipid peroxidation. Ferroptosis is a type of programmed cell death caused by iron-dependent peroxidation of lipids; ACSL4 and glutathione peroxidase 4 positively and negatively regulate ferroptosis, respectively. In addition, ACSL4 is an essential regulator of fatty acid (FA) metabolism. ACSL4 remodels the phospholipid composition of cell membranes, regulates steroidogenesis, and balances eicosanoid biosynthesis. In addition, ACSL4-mediated metabolic reprogramming and antitumor immunity have attracted much attention in cancer biology. Because it facilitates the cross-talk between ferroptosis and FA metabolism, ACSL4 is also a research hotspot in metabolic diseases and ischemia/reperfusion injuries. In this review, we focus on the structure, biological function, and unique role of ASCL4 in various human diseases. Finally, we propose that ACSL4 might be a potential therapeutic target.

Transcriptome analysis reveals FABP5 as a key player in the development of chicken abdominal fat, regulated by miR-122-5p targeting

BACKGROUND

The development of abdominal fat and meat quality are closely related and can impact economic efficiency. In this study, we conducted transcriptome sequencing of the abdominal fat tissue of Gushi chickens at 6, 14, 22, and 30 weeks, and selected key miRNA-mRNA regulatory networks related to abdominal fat development through correlation analysis.

RESULTS

A total of 1893 differentially expressed genes were identified. Time series analysis indicated that at around 6 weeks, the development of chicken abdominal fat was extensively regulated by the TGF-β signaling pathway, Wnt signaling pathway, and PPAR signaling pathway. However, at 30 weeks of age, the apoptosis signaling pathway was the most significant, and correlation analysis revealed several genes highly correlated with abdominal fat development, including Fatty Acid Binding Protein 5 (FABP5). Based on miRNA transcriptome data, it was discovered that miR-122-5p is a potential target miRNA for FABP5. Cell experiments showed that miR-122-5p can directly target FABP5 to promote the differentiation of preadipocytes.

CONCLUSION

The present study confirms that the key gene FABP5 and its target gene miR-122-5p are critical regulatory factors in the development of chicken abdominal fat. These results provide new insights into the molecular regulatory mechanisms associated with the development of abdomen-al fat in chickens.

MiR-196b-3p and miR-450b-3p are key regulators of adipogenesis in porcine intramuscular and subcutaneous adipocytes

BACKGROUND

As components of white adipose tissue, porcine intramuscular (IM) and subcutaneous (SC) adipocytes undergo similar differentiation and adipogenesis processes. However, the adipogenic capacity of IM adipocytes is weaker than that of SC adipocytes. Identifying key regulators underlying this difference between IM and SC adipocytes will benefit pig breeding.

RESULTS

In this study, we used BGISEQ-500 sequencing technology to analyze the expression of small RNAs in primary cultured IM and SC adipocytes on day 8 after adipogenic induction, and found 32-fold higher miR-196b-3p expression, as well as 8-fold lower miR-450b-3p expression in IM adipocytes than in SC adipocytes. Functional studies revealed that miR-196b-3p inhibits adipogenesis by targeting CD47 via the AMPK signaling pathway, and its effect was attenuated by the specific p-AMPKα activator AICAR. We also found that miR-450b-3p promotes adipogenesis by targeting SIRT1 via the Wnt/β-catenin signaling pathway, and its effect was weakened by the Wnt/β-catenin signaling activator LiCl.

CONCLUSIONS

Our findings suggest that miR-196b-3p and miR-450b-3p are novel key regulatory factors that play opposite roles in porcine adipogenesis, helping us decipher the regulatory differences between porcine IM and SC fat deposition.

The ACSL4 Network Regulates Cell Death and Autophagy in Diseases

Lipid metabolism, cell death, and autophagy are interconnected processes in cells. Dysregulation of lipid metabolism can lead to cell death, such as via ferroptosis and apoptosis, while lipids also play a crucial role in the regulation of autophagosome formation. An increased autophagic response not only promotes cell survival but also causes cell death depending on the context, especially when selectively degrading antioxidant proteins or organelles that promote ferroptosis. ACSL4 is an enzyme that catalyzes the formation of long-chain acyl-CoA molecules, which are important intermediates in the biosynthesis of various types of lipids. ACSL4 is found in many tissues and is particularly abundant in the brain, liver, and adipose tissue. Dysregulation of ACSL4 is linked to a variety of diseases, including cancer, neurodegenerative disorders, cardiovascular disease, acute kidney injury, and metabolic disorders (such as obesity and non-alcoholic fatty liver disease). In this review, we introduce the structure, function, and regulation of ACSL4; discuss its role in apoptosis, ferroptosis, and autophagy; summarize its pathological function; and explore the potential implications of targeting ACSL4 in the treatment of various diseases.

Research progress of non-coding RNAs regulation on intramuscular adipocytes in domestic animals

Intramuscular fat (IMF) is the main determinant of the economic value of domestic animal meat, and has a vital impact on the sensory quality characteristics, while the content of IMF is mainly determined by the size and number of intramuscular adipocytes. In recent years, due to the development of sequencing technology and omics technology, a large number of non-coding RNAs have been identified in intramuscular adipocytes. Non-coding RNAs are a kind of RNA regulatory factors with biological functions but without translation function, which mainly include microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). These non-coding RNAs regulate the key genes of intramuscular adipocyte growth and development at post-transcriptional level through a variety of regulatory mechanisms, and affect the number and size of intramuscular adipocytes, thus affecting the content of IMF. Here, the review summarizes the candidate non-coding RNAs (miRNAs, lncRNAs, circRNAs) and genes involved in the regulation of intramuscular adipocytes, the related regulation mechanism and signaling pathways, in order to provide reference for further clarifying the molecular regulation mechanism of non-coding RNAs on intramuscular adipocytes in domestic animals.

Interacting Networks of the Hypothalamic-Pituitary-Ovarian Axis Regulate Layer Hens Performance

Egg production is a vital biological and economic trait for poultry breeding. The 'hypothalamic-pituitary-ovarian (HPO) axis' determines the egg production, which affects the layer hens industry income. At the organism level, the HPO axis is influenced by the factors related to metabolic and nutritional status, environment, and genetics, whereas at the cellular and molecular levels, the HPO axis is influenced by the factors related to endocrine and metabolic regulation, cytokines, key genes, signaling pathways, post-transcriptional processing, and epigenetic modifications. MiRNAs and lncRNAs play a critical role in follicle selection and development, atresia, and ovulation in layer hens; in particular, miRNA is known to affect the development and atresia of follicles by regulating apoptosis and autophagy of granulosa cells. The current review elaborates on the regulation of the HPO axis and its role in the laying performance of hens at the organism, cellular, and molecular levels. In addition, this review provides an overview of the interactive network regulation mechanism of the HPO axis in layer hens, as well as comprehensive knowledge for successfully utilizing their genetic resources.

Meta-analysis of miR-34 target mRNAs using an integrative online application

Members of the microRNA-34/miR-34 family are induced by the p53 tumor suppressor and themselves possess tumor suppressive properties, as they inhibit the translation of mRNAs that encode proteins involved in processes, such as proliferation, migration, invasion, and metastasis. Here we performed a comprehensive integrative meta-analysis of multiple computational and experimental miR-34 related datasets and developed tools to identify and characterize novel miR-34 targets. A miR-34 target probability score was generated for every mRNA to estimate the likelihood of representing a miR-34 target. Experimentally validated miR-34 targets were strongly enriched among mRNAs with the highest scores providing a proof of principle for our analysis. We integrated the results from the meta-analysis in a user-friendly METAmiR34TARGET website (www.metamir34target.com/) that allows to graphically represent the meta-analysis results for every mRNA. Moreover, the website harbors a screen function, which allows to select multiple miR-34-related criteria/analyses and cut-off values to facilitate the stringent and comprehensive prediction of relevant miR-34 targets in expression data obtained from cell lines and tumors/tissues. Furthermore, information on more than 200 miR-34 target mRNAs, that have been experimentally validated so far, has been integrated in the web-tool. The website and datasets provided here should facilitate further investigation into the mechanisms of tumor suppression by the p53/miR-34 connection and identification of potential cancer drug targets.

Identification and characterization of circRNAs related to meat quality during embryonic development of the longissimus dorsi muscle in two pig breeds

Meat quality, an important economic trait, is regulated by many factors, especially by genetic factors, including coding genes, miRNAs, and lncRNAs. Recent studies have elucidated that circRNAs also play a key role in muscle development and lipid deposition. However, the functions and regulatory mechanisms of circRNAs in meat quality remain mostly unknown. The circRNA expression profiles between Huainan pigs (Chinese indigenous pigs, fat-type, Huainan HN) and Large White pigs (Western commercial pigs, lean-type, LW) in the longissimus dorsi (LD) muscle at 38, 58, and 78 days post conception (dpc) were compared by sequencing. In total, 39,887 circRNAs were identified in 18 samples, and 60, 78, and 86 differentially expressed circRNAs (DECs) were found at the three stages mentioned above between these two breeds. The parent genes of DECs were enriched in myogenesis, proliferation, adipogenesis and muscle fiber-type transition. The circRNA-miRNA interaction networks included 38 DECs and 47 miRNAs, and these miRNAs were involved in muscle development and lipid metabolism. Two shared DECs (circ_0030593 and circ_0032760) of these three stages were selected, their head-to-tail junction sites were validated by Sanger sequencing, and RT‒qPCR results suggested that these two DECs might be involved in intramuscular fat deposition. These findings provide a basis for understanding the role of circRNAs in meat quality.

miR-381-3p Inhibits Intramuscular Fat Deposition through Targeting FABP3 by ceRNA Regulatory Network

Intramuscular fat (IMF) deposition is an important determinant of pork quality and a complex process facilitated by non-coding ceRNAs. In this study, 52 Berkshire × Anqing Sixwhite crossbred pigs were slaughtered to measure eight carcass and pork quality traits. Whole-transcriptome sequencing analysis was performed using longissimus dorsi samples of six low- and high-IMF samples; 34 ceRNA networks, based on 881, 394, 158 differentially expressed (DE) lncRNAs, miRNAs, and mRNAs, were constructed. Following weighted gene co-expression network analysis between the low and high IMF, only one ceRNA, lncRNA4789/miR-381-3p/FABP3, that showed similar DE trend in longissimus dorsi tissue was retained. Dual-luciferase reporter assays further indicated that FABP3 was a direct, functional target of miR-381-3p, where miR-381-3p overexpression inhibited the mRNA and protein expression of FABP3. In addition, overexpressed lncRNA4789 attenuated the effect of miR-381-3p on FABP3 by sponging miR-381-3p. Cell function verification experiment demonstrated that miR-381-3p suppressed IMF deposition by inhibiting preadipocyte cell differentiation and lipid droplet deposition via the suppression of FABP3 expression in the peroxisome proliferator-activated receptor signalling pathway, whereas lncRNA4789 rescued FABP3 expression by sponging miR-381-3p. Our study may aid in identifying novel molecular markers for its optimization in IMF which is of importance in breeding for improving pork quality.

MiR-23b Promotes Porcine Preadipocyte Differentiation via SESN3 and ACSL4

Genetic improvement of pork quality is one of the hot topics in pig germplasm innovation. Backfat thickness and intramuscular fat content are important indexes of meat quality. MiRNAs are becoming recognized as a crucial regulator of adipose development. Therefore, it is crucial to understand how miR-23b regulates fat metabolism at the molecular level. In the present study, Oil Red O staining, and Western blot were used to evaluate the effect of miR-23b on the differentiation of porcine preadipocytes. Dual-luciferase reporter gene assay, pulldown, and RIP were used to reveal the mechanism of miR-23b regulating cell differentiation. The findings demonstrated that miR-23b promotes the expression of adipogenic factors and increases the content of lipid droplets, thus promoting the differentiation of preadipocytes. Further research found that miR-23b can directly bind to the 3’UTR of SESN3 to regulate adipogenic differentiation. In addition, it was speculated that miR-23b controls cell differentiation by positively regulating the expression of ACSL4 in other ways. Here, we demonstrate that miR-23b promotes the differentiation of porcine preadipocytes by targeting SESN3 and promoting the expression of ACSL4. The present study is meaningful to the improvement of pork quality and the development of animal husbandry.

Transcriptomics-Based Study of Differentially Expressed Genes Related to Fat Deposition in Tibetan and Yorkshire Pigs

Fat deposition traits are one of the key factors in pig production and breeding. The fat deposition capacity of pigs mainly affects the quality of pork and pig productivity. The aim of this study was to analyze the differential expression of mRNA levels in dorsal adipose tissue of Tibetan and York pigs at different growth stages using transcriptomic data to estimate key genes that regulate fat deposition in pigs. The results showed that a total of 32,747 positively expressed genes were present in the dorsal adipose tissue of the two breeds. Differentially expressed gene (DEG) screening of multiple combinations between the two breeds yielded 324 DEGS. Gene ontology (GO) biofunctional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that these DEGS were mainly involved in lipid metabolic pathways, steroid biosynthetic pathways and lipid biosynthetic processes, sterol biosynthetic processes, brown adipocyte differentiation, and other pathways related to lipid deposition and metabolism. The results showed that ACACA, SLC2A4 and THRSP genes positively regulated the lipid deposition ability and CHPT1 gene negatively regulated the lipid deposition ability in pigs. The results of this experiment suggest a theoretical basis for further studies on the regulatory mechanisms of fat deposition in pigs.

Circular RNA Profiling Identifies Novel circPPARA that Promotes Intramuscular Fat Deposition in Pigs

Intramuscular fat (IMF) content plays an important role in pork quality. Circular RNAs (circRNAs) implicate various biological processes; however, the regulatory mechanisms and functions of circRNAs in porcine IMF remains elusive. Hence, the study assessed the circRNA expression profiling in the longissimus dorsi muscle of pigs with high (H) and low (L) IMF content to unravel their regulatory functions in improving meat quality. The RNA sequencing analysis identified 29,732 circRNAs from six sampled pigs, most of which were exon-derived. In the muscle, 336 were differentially expressed (DE) between the H and L IMF groups; 196 circRNAs were upregulated, and 140 were downregulated. Subsequent qRT-PCR validation of 10 DE circRNAs revealed expression patterns consistent with the RNA-seq data. Gene ontology and KEGG enrichment analysis revealed that most significantly enriched DE circRNAs' host genes were linked to lipid metabolism and adipogenesis processes. The circRNA-miRNA regulatory network analysis found several circRNAs targeting miRNAs associated with adipogenesis. Finally, a novel circRNA, circPPARA, was identified with the expression positively correlated with the IMF content. Detailed analysis revealed that circPPARA was formed via head-to-tail splicing and was more stable than the linear PPARA, predominantly located in the cytoplasm. Functional studies using overexpression and siRNA constructs demonstrated that circPPARA promotes differentiation and hinders the proliferation of porcine intramuscular preadipocytes. Moreover, the dual-luciferase assay revealed that circPPARA adsorbed miR-429 and miR-200b, thereby promoting intramuscular adipogenesis in pigs. Our results identified a candidate circRNA, circPPARA, that affects porcine IMF content. The study provides knowledge of the regulatory functions of circRNAs in intramuscular adipogenesis and abundant resource for future research on circRNAs in pigs.

ACSL4 Directs Intramuscular Adipogenesis and Fatty Acid Composition in Pigs

Simple Summary

In the livestock industry, intramuscular fat content is an important indicator of the meat quality of domestic animals. The variations of the Acyl-CoA Synthetase Long-Chain Family Member 4 (ACSL4) gene locus are associated with intramuscular fat content in different pig populations, but the detailed molecular function of ACSL4 in pig intramuscular adipogenesis remains obscure. Our study reveals the function of ACSL4 in pig intramuscular adipogenesis and provides new clues for improving the palatability of meat and enhancing the nutritional value of pork for human health.

Abstract

The intramuscular fat is a major quality trait of meat, affecting sensory attributes such as flavor and texture. Several previous GWAS studies identified Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4) gene as the candidate gene to regulate intramuscular fat content in different pig populations, but the underlying molecular function of ACSL4 in adipogenesis within pig skeletal muscle is not fully investigated. In this study, we isolated porcine endogenous intramuscular adipocyte progenitors and performed ACSL4 loss- and gain-of-function experiments during adipogenic differentiation. Our data showed that ACSL4 is a positive regulator of adipogenesis in intramuscular fat cells isolated from pigs. More interestingly, the enhanced expression of ACSL4 in pig intramuscular adipocytes could increase the cellular content of monounsaturated and polyunsaturated fatty acids, such as gamma-L eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA). The above results not only confirmed the function of ACSL4 in pig intramuscular adipogenesis and meat quality attributes, but also provided new clues for the improvement of the nutritional value of pork for human health.

Long non-coding RNA NEAT1 facilitates the growth, migration, and invasion of ovarian cancer cells via the let-7 g/MEST/ATGL axis

Background/Aim

Growing evidence indicates a significant role of long non-coding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1) in ovarian cancer, a frequently occurring malignant tumor in women; however, the possible effects of an interplay of NEAT1 with microRNA (miRNA or miR) let-7 g in ovarian cancer are not known. The current study aimed to investigate the role of the NEAT1/let-7 g axis in the growth, migration, and invasion of ovarian cancer cells and explore underlying mechanisms.

Methods

NEAT1 expression levels were examined in clinical tissue samples and cell lines. The relationships between NEAT1, let-7 g, and MEST were then analyzed. Gain- or loss-of-function approaches were used to manipulate NEAT1 and let-7 g. The effects of NEAT1 on cell proliferation, migration, invasion, and apoptosis were evaluated. Mouse xenograft models of ovarian cancer cells were established to verify the function of NEAT1 in vivo.

Results

NEAT1 expression was elevated while let-7 g was decreased in ovarian cancer clinical tissue samples and cell lines. A negative correlation existed between NEAT1 and let-7 g, whereby NEAT1 competitively bound to let-7 g and consequently down-regulate let-7 g expression. By this mechanism, the growth, migration, and invasion of ovarian cancer cells were stimulated. In addition, let-7 g targeted mesoderm specific transcript (MEST) and inhibited its expression, leading to promotion of adipose triglyceride lipase (ATGL) expression and inhibition of ovarian cancer cell growth, migration, and invasion. However, the effect of let-7 g was abolished by overexpression of MEST. Furthermore, silencing of NEAT1 decreased the xenograft tumor growth by decreasing MEST while up-regulating let-7 g and ATGL.

Conclusions

Cumulatively, the findings demonstrated that NEAT1 could promote malignant phenotypes of ovarian cancer cells by regulating the let-7 g/MEST/ATGL signaling axis. Therefore, NEAT1 can be regarded as an important molecular target and biomarker for ovarian cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02018-3.

Insight into Crosstalk between Ferroptosis and Necroptosis: Novel Therapeutics in Ischemic Stroke

Ferroptosis is a nonapoptotic form of cell death characterized by iron-dependent accumulation of lipid hydroperoxides to lethal levels. Necroptosis, an alternative form of programmed necrosis, is regulated by receptor-interacting protein (RIP) 1 activation and by RIP3 and mixed-lineage kinase domain-like (MLKL) phosphorylation. Ferroptosis and necroptosis both play important roles in the pathological progress in ischemic stroke, which is a complex brain disease regulated by several cell death pathways. In the past few years, increasing evidence has suggested that the crosstalk occurs between necroptosis and ferroptosis in ischemic stroke. However, the potential links between ferroptosis and necroptosis in ischemic stroke have not been elucidated yet. Hence, in this review, we overview and analyze the mechanism underlying the crosstalk between necroptosis and ferroptosis in ischemic stroke. And we find that iron overload, one mechanism of ferroptosis, leads to mitochondrial permeability transition pore (MPTP) opening, which aggravates RIP1 phosphorylation and contributes to necroptosis. In addition, heat shock protein 90 (HSP90) induces necroptosis and ferroptosis by promoting RIP1 phosphorylation and suppressing glutathione peroxidase 4 (GPX4) activation. In this work, we try to deliver a new perspective in the exploration of novel therapeutic targets for the treatment of ischemic stroke.

MicroRNA-489-3p promotes adipogenesis by targeting the Postn gene in 3T3-L1 preadipocytes

AIMS

Accumulating evidence indicates that a number of microRNAs (miRNAs) serve as essential regulators during adipogenesis and adipolysis in humans and animals and play critical roles in the development of fat tissue. In this study, we aimed to determine the functional role and underlying regulatory mechanism of microRNA-489-3p (miR-489) in adipocytes.

MATERIALS AND METHODS

The expression patterns of miR-489 in mice were measured by qRT-PCR. Overexpression and knockdown of miR-489 by mimic and inhibitor transfections in 3T3-L1 preadipocytes revealed the regulatory effect of miR-489 on cellular proliferation and differentiation and energy turnover. Furthermore, RNA-seq, bioinformatics prediction, and dual luciferase reporter assays were used to identify the direct target of miR-489.

KEY FINDINGS

The results showed that miR-489 was highly expressed in the visceral fat tissue of adult mice, and obese mice exhibited higher levels of miR-489 than normal mice. Overexpression of miR-489 suppressed proliferation but promoted adipogenic differentiation and lipid accumulation in the cells. Mitochondrial oxidation also fluctuated in the cells due to the high expression of miR-489. Notably, knockdown of miR-489 did not have a strong opposing effect on the cells. Periostin (Postn) was identified as a direct target gene for miR-489, and silencing the Postn gene similarly stimulated adipogenesis and differentiation of adipocytes.

SIGNIFICANCE

miR-489 provides a strong driving force for adipogenesis metabolism and adipocyte differentiation by targeting the Postn gene. This result may contribute to the treatment of obesity.

Role of microRNAs in myogenesis and their effects on meat quality in pig - A review

The demand for food is increasing day by day because of the increasing global population. Therefore, meat, the easiest and largely available source of protein, needs to be produced in large amounts with good quality. The pork industry is a significant shareholder in fulfilling the global meat demands. Notably, myogenesis- development of muscles during embryogenesis- is a complex mechanism which culminates in meat production. But the molecular mechanisms which govern the myogenesis are less known. The involvement of miRNAs in myogenesis and meat quality, which depends on factors such as myofiber composition and intramuscular fat contents which determine the meat color, flavor, juiciness, and water holding capacity, are being extrapolated to increase both the quantity and quality of pork. Various kinds of microRNAs (miRNAs), miR-1, miR-21, miR22, miR-27, miR-34, miR-127, miR-133, miR-143, miR-155, miR-199, miR-206, miR-208, miR-378, and miR-432 play important roles in pig skeletal muscle development. Further, the quality of meat also depends upon myofiber which is developed through the expression of different kinds of miRNAs at different stages. This review will focus on the mechanism of myogenesis, the role of miRNAs in myogenesis, and meat quality with a focus on the pig.

miR-458b-5p regulates ovarian granulosa cells proliferation through Wnt/β-catenin signaling pathway by targeting catenin beta-1

OBJECTIVE

Ovarian follicular development, which dependent on the proliferation and differentiation of granulosa cells (GCs), is a complex biological process in which miRNA plays an important role. Our previous study showed that miR-458b-5p is associated with ovarian follicular development in chicken. The detailed function and molecular mechanism of miR-458b-5p in GCs is unclear.

METHODS

The luciferase reporter assay was used to verify the targeting relationship between miR-458b-5p and catenin beta-1 (CTNNB1), which is an important transcriptional regulatory factor of the Wnt/β-catenin pathway. The cell counting kit-8 (CCK-8) assay, flow cytometry with propidium iodide (PI) and annexin V-fluorescein isothiocyanate (FITC) labeling were applied to explore the effect of miR-458b-5p on proliferation, cell cycle and apoptosis of chicken GCs. Quantitative real-time polymerase chain reaction and Western blot were used to detect the mRNA and protein expression levels.

RESULTS

We demonstrated that the expression of miR-458b-5p and CTNNB1 showed the opposite relationship in GCs and theca cells of hierarchical follicles. The luciferase reporter assay confirmed that CTNNB1 is the direct target of miR-458b-5p. Using CCK-8 assay and flow cytometry with PI and Annexin V-FITC labeling, we observed that transfection with the miR-458b-5p mimics significantly reduced proliferation and has no effects on apoptosis of chicken GCs. In addition, miR-458b-5p decreased the mRNA and protein expression of CD44 molecule and matrix metallopeptidase 7, which are the downstream effectors of CTNNB1 in Wnt/β-Catenin pathway and play functional roles in cell proliferation.

CONCLUSION

Taken together, the data indicate that miR-458b-5p regulates ovarian GCs proliferation through Wnt/β-catenin signaling pathway by targeting CTNNB1, suggesting that miR-458b-5p and its target gene CTNNB1 may potentially play a role in chicken ovarian follicular development.