The role of BAMBI in regulating adipogenesis and myogenesis and the association between its polymorphisms and growth traits in cattle

Identification of Growth-Related Gene BAMBI and Analysis of Gene Structure and Function in the Pacific White Shrimp Litopenaeus vannamei

As one of the most important aquaculture species in the world, the improvement of growth traits of the Pacific white shrimp (Litopenaeus vannamei), has always been a primary focus. In this study, we conducted SNP-specific locus analysis and identified a growth-related gene, BAMBI, in L. vannamei. We analyzed the structure and function of LvBAMBI using genomic, transcriptomic, metabolomic, and RNA interference (RNAi) assays. The LvBAMBI possessed highly conserved structural domains and widely expressed in various tissues. Knockdown of LvBAMBI significantly inhibited the gain of body length and weight of the shrimp, underscoring its role as a growth-promoting factor. Specifically, knockdown of LvBAMBI resulted in a significant downregulation of genes involved in lipid metabolism, protein synthesis, catabolism and transport, and immunity. Conversely, genes related to glucose metabolism exhibited significant upregulations. Analysis of differential metabolites (DMs) in metabolomics further revealed that LvBAMBI knockdown may primarily affect shrimp growth by regulating biological processes related to lipid and glucose metabolism. These results suggested that LvBAMBI plays a crucial role in regulating lipid metabolism, glucose metabolism, and protein transport in shrimp. This study provides valuable insights for future research and utilization of BAMBI genes in shrimp and crustaceans.

Adipose tissue depot specific expression and regulation of fibrosis-related genes and proteins in experimental obesity

Transforming growth factor beta (Tgfb) is a well-studied pro-fibrotic cytokine, which upregulates cellular communication network factor 2 (Ccn2), collagen, and actin alpha 2, smooth muscle (Acta2) expression. Obesity induces adipose tissue fibrosis, which contributes to metabolic diseases. This work aimed to analyze the expression of Tgfb, Ccn2, collagen1a1 (Col1a1), Acta2 and BMP and activin membrane-bound inhibitor (Bambi), which is a negative regulator of Tgfb signaling, in different adipose tissue depots of mice fed a standard chow, mice fed a high fat diet (HFD) and ob/ob mice. Principally, these genes were low expressed in brown adipose tissues and this difference was less evident for the ob/ob mice. Ccn2 and Bambi protein as well as mRNA expression, and collagen1a1 mRNA were not induced in the adipose tissues upon HFD feeding whereas Tgfb and Acta2 mRNA increased in the white fat depots. Immunoblot analysis showed that Acta2 protein was higher in subcutaneous and perirenal fat of these mice. In the ob/ob mice, Ccn2 mRNA and Ccn2 protein were upregulated in the fat depots. Here, Tgfb, Acta2 and Col1a1 mRNA levels and serum Tgfb protein were increased. Acta2 protein was, however, not higher in subcutaneous and perirenal fat of these mice. Col6a1 mRNA was shown before to be higher in obese fat tissues. Current analysis proved the Col6a1 protein was induced in subcutaneous fat of HFD fed mice. Notably, Col6a1 was reduced in perirenal fat of ob/ob mice in comparison to the respective controls. 3T3-L1 cells express Ccn2 and Bambi protein, whose levels were not changed by fatty acids, leptin, lipopolysaccharide, tumor necrosis factor and interleukin-6. All of these factors led to higher Tgfb in 3T3-L1 adipocyte media but did not increase its mRNA levels. Free fatty acids induced necrosis whereas apoptosis did not occur in any of the in vitro incubations excluding cell death as a main reason for higher Tgfb in cell media. In summary, Tgfb mRNA is consistently induced in white fat tissues in obesity but this is not paralleled by a clear increase of its target genes. Moreover, discrepancies between mRNA and protein expression of Acta2 were observed. Adipocytes seemingly do not contribute to higher Tgfb mRNA levels in obesity. These cells release more Tgfb protein when challenged with obesity-related metabolites connecting metabolic dysfunction and fibrosis.

Bta-miR-181d and Bta-miR-196a mediated proliferation, differentiation, and apoptosis in Bovine Myogenic Cells

Skeletal muscle is an important component of livestock and poultry organisms. The proliferation and differentiation of myoblasts are highly coordinated processes, which rely on the regulation of miRNA. MiRNAs are widely present in organisms and play roles in various biological processes, including cell proliferation, differentiation, and apoptosis. MiR-181d and miR-196a, identified as tumor suppressors, have been found to be involved in cell proliferation, apoptosis, directed differentiation, and cancer cell invasion. However, their role in beef cattle skeletal muscle metabolism remains unclear. In this study, we discovered that overexpression of bta-miR-181d and bta-miR-196a in Qinchuan cattle myoblasts inhibited proliferation and apoptosis while promoting myogenic differentiation through EDU staining, flow cytometry analysis, immunofluorescence staining, and Western blotting. RNA-seq analysis of differential gene expression revealed that after overexpression of bta-miR-181d and bta-miR-196a, the differentially expressed genes were mainly enriched in the PI3K-Akt and MAPK signaling pathways. Furthermore, the phosphorylation levels of key proteins p-AKT in the PI3K signaling pathway and p-MAPK in the MAPK signaling pathway were significantly decreased after overexpression of bta-miR-181d and bta-miR-196a. Overall, this study provides preliminary evidence that bta-miR-181d and bta-miR-196a may regulate proliferation, apoptosis, and differentiation processes in Qinchuan cattle myoblasts by affecting the phosphorylation status of key proteins in PI3K-Akt and MAPK-ERK signaling pathways.

BMP and activin receptor membrane bound inhibitor: BAMBI has multiple roles in gene expression and diseases (Review)

BMP and activin membrane-bound inhibitor (BAMBI) is a transmembrane glycoprotein, known as a pseudo-receptor for TGFβ, as, while its extracellular domain is similar to that of type I TGFβ receptors, its intracellular structure is shorter and lacks a serine/threonine phosphokinase signaling motif. BAMBI can regulate numerous biological phenomena, including glucose and lipid metabolism, inflammatory responses, and cell proliferation and differentiation. Furthermore, abnormal expression of BAMBI at the mRNA and protein levels contributes to various human pathologies, including obesity and cancer. In the present review, the structure of BAMBI is briefly introduced and its associated signaling pathways and physiological functions are described. Understanding of BAMBI structure and function may contribute to knowledge regarding the occurrence of diseases, including obesity and diabetes, among others. The present review provides a theoretical foundation for the development of BAMBI as a potential biomarker or therapeutic target.

MEF2C Expression Is Regulated by the Post-transcriptional Activation of the METTL3-m6A-YTHDF1 Axis in Myoblast Differentiation

N⁶-methyladenosine (m⁶A) plays an essential role in regulating gene expression. However, the effect of m⁶A on skeletal myoblast differentiation and the underlying mechanisms are still unclear. Here, we ascertained mRNA m⁶A methylation exhibited declined changes during bovine skeletal myoblast differentiation, and both MEF2C mRNA expression and m⁶A levels were significantly increased during myoblast differentiation. We found that MEF2C with mutated m⁶A sites significantly inhibited myoblast differentiation compared with wild-type MEF2C. METTL3 promoted MEF2C protein expression through posttranscriptional modification in an m⁶A-YTHDF1-dependent manner. Moreover, MEF2C promoted the expression of METTL3 by binding to its promoter. These results revealed that there is a positive feedback loop between these molecules in myoblast differentiation. Our study provided new insights into skeletal muscle differentiation and fusion, which may provide an RNA methylation-based approach for molecular genetics and breeding in livestock as well as for the treatment of muscle-related diseases.

m6A Methylases Regulate Myoblast Proliferation, Apoptosis and Differentiation

Simple Summary

N⁶-methyladenosine (m⁶A) is the most prevalent methylation modification in eukaryotic mRNA, and it plays an important role in regulating gene expression. Previous studies found that m⁶A methylation plays a role in mammalian skeletal muscle development. Skeletal muscle is an important factor that regulates livestock muscle quality and maintains metabolic homeostasis, and skeletal myogenesis is regulated by a series of transcription factors. However, the role of m⁶A in bovine skeletal myogenesis is unclear. In this study, we examined the expression patterns of the m⁶A methylase genes METTL3, METTL14, WTAP, FTO and ALKBH5 in bovine skeletal muscle tissue and during myogenesis in myoblasts. Furthermore, we used bovine skeletal muscle myoblasts as the object of study to discover the regulatory role of these genes in the process of skeletal myogenesis in vitro. Our findings indicate that these five m⁶A methylases have pronounced and diverse functions in regulating bovine skeletal myoblast proliferation, apoptosis and myogenic differentiation, which can contribute to further understanding the roles of m⁶A in skeletal muscle development.

Abstract

N⁶-methyladenosine (m⁶A) plays an important role in regulating gene expression. Previous studies found that m⁶A methylation affects skeletal muscle development. However, the effect of m⁶A methylases on bovine skeletal myogenesis is still unclear. Here, we found that the expression of m⁶A demethylases (FTO and ALKBH5) was significantly higher in the longissimus dorsi muscle of adult cattle than in newborn cattle. In contrast, the expression of m⁶A methyltransferases (METTL3, METTL14 and WTAP) was reduced. The mRNA expression of all five genes was found to be increased during the myogenesis of myoblasts in vitro. Knockdown of FTO or METTL3 promoted myoblast proliferation, inhibited myoblast apoptosis and suppressed myogenic differentiation, whereas ALKBH5 knockdown had the opposite effect. METTL14 knockdown enhanced myoblast proliferation and impaired myogenic differentiation. WTAP knockdown attenuated proliferation and contributed to apoptosis but did not affect differentiation. Furthermore, the functional domains of these five m⁶A methylases are conserved across species. Our results suggest that m⁶A methylases are involved in regulating skeletal muscle development and that there may be a complex network of m⁶A methylation regulating skeletal myogenesis.

Genome-wide association studies for growth traits in broilers

BACKGROUND

The identification of markers and genes for growth traits may not only benefit for marker assist selection /genomic selection but also provide important information for understanding the genetic foundation of growth traits in broilers.

RESULTS

In the current study, we estimated the genetic parameters of eight growth traits in broilers and carried out the genome-wide association studies for these growth traits. A total of 113 QTNs discovered by multiple methods together, and some genes, including ACTA1, IGF2BP1, TAPT1, LDB2, PRKCA, TGFBR2, GLI3, SLC16A7, INHBA, BAMBI, APCDD1, GPR39, and GATA4, were identified as important candidate genes for rapid growth in broilers.

CONCLUSIONS

The results of this study will provide important information for understanding the genetic foundation of growth traits in broilers.