Tissue Expression Analysis, Cloning, and Characterization of the 5'-Regulatory Region of the Bovine LATS1 Gene

Genome-wide scans identify biological and metabolic pathways regulating carcass and meat quality traits in beef cattle

Genome association studies (GWAS) provides knowledge about the genetic architecture of beef-related traits that allow linking the target phenotype to genomic information aiding breeding decision. Thus, the present study aims to uncover the genetic mechanism involved in carcass (REA: rib eye area, BF: backfat thickness, and HCW: hot carcass weight) and meat quality traits (SF: shear-force, MARB: marbling score, and IMF: intramuscular fat content) in Nellore cattle. For this, 6910 young bulls with phenotypic information and 23,859 animals genotyped with 435 k markers were used to perform the weighted single-step GBLUP (WssGBLUP) approach, considering two iterations. The top 10 genomic regions explained 8.13, 11.81, and 9.58% of the additive genetic variance, harboring a total of 119, 143, and 95 positional candidate genes for REA, BF, and HCW, respectively. For meat quality traits, the top 10 windows explained a large proportion of the total genetic variance for SF (14.95%), MARB (17.56%), and IMF (21.41%) surrounding 92, 155, and 111 candidate genes, respectively. Relevant candidate genes (CAST, PLAG1, XKR4, PLAGL2, AQP3/AQP7, MYLK2, WWOX, CARTPT, and PLA2G16) are related to physiological aspects affecting growth, carcass, meat quality, feed intake, and reproductive traits by signaling pathways controlling muscle control, key signal metabolic molecules INS / IGF-1 pathway, lipid metabolism, and adipose tissue development. The GWAS results provided insights into the genetic control of the traits studied and the genes found are potential candidates to be used in the improvement of carcass and meat quality traits.

Unlocking the Transcriptional Control of NCAPG in Bovine Myoblasts: CREB1 and MYOD1 as Key Players

Muscle formation directly determines meat production and quality. The non-SMC condensin I complex subunit G (NCAPG) is strongly linked to the growth features of domestic animals because it is essential in controlling muscle growth and development. This study aims to elucidate the tissue expression level of the bovine NCAPG gene, and determine the key transcription factors for regulating the bovine NCAPG gene. In this study, we observed that the bovine NCAPG gene exhibited high expression levels in longissimus dorsi and spleen tissues. Subsequently, we cloned and characterized the promoter region of the bovine NCAPG gene, consisting of a 2039 bp sequence, through constructing the deletion fragment double-luciferase reporter vector and site-directed mutation-identifying core promoter region with its key transcription factor binding site. In addition, the key transcription factors of the core promoter sequence of the bovine NCAPG gene were analyzed and predicted using online software. Furthermore, by integrating overexpression experiments and the electrophoretic mobility shift assay (EMSA), we have shown that cAMP response element binding protein 1 (CREB1) and myogenic differentiation 1 (MYOD1) bind to the core promoter region (-598/+87), activating transcription activity in the bovine NCAPG gene. In conclusion, these findings shed important light on the regulatory network mechanism that underlies the expression of the NCAPG gene throughout the development of the muscles in beef cattle.

FOXO1 regulates the formation of bovine fat by targeting CD36 and STEAP4

Intramuscular fat content is closely related to the quality of beef, where the forkhead box protein O1 (FOXO1) is involved in adipocyte differentiation and lipid metabolism, but the specific mechanism of its involvement is still unclear. In this study, interfering with FOXO1 promoted the G1/S transformation of bovine adipocytes by enhancing the expression of proliferation marker genes PCNA, CDK1, CDK2, CCNA2, CCNB1, and CCNE2, thereby positively regulating the proliferation of bovine adipocytes. Additionally, interfering with FOXO1 negatively regulated the expression of adipogenic differentiation marker genes PPARG and CEBPA, as well as lipid anabolism marker genes ACC, FASN, SCD1, SREBP1, FABP4, ACSL1, LPL, and DGAT1, thus reducing triglyceride (TG) content and inhibiting the generation of lipid droplets in bovine adipocytes. A combination of transcriptomic and metabolomics analyses revealed that FOXO1 could regulate the lipogenesis of cattle by influencing the AMPK and PI3K/AKT pathways. Importantly, chromatin immunoprecipitation (ChIP) and site-directed mutagenesis revealed that FOXO1 could regulate bovine lipogenesis by binding to the promoter regions of the CD36 and STEAP4 genes and affecting their transcriptional activities. These results provide a foundation for studying the role and molecular mechanism of FOXO1 in the bovine adipogenesis.

Interaction of C/EBPβ with SMAD2 and SMAD4 genes induces the formation of lipid droplets in bovine myoblasts

As a key component of Transforming growth factor-β (TGF-β) pathway, Smad2 has many crucial roles in a variety of cellular processes, but it cannot bind DNA without complex formation with Smad4. In the present study, the molecular mechanism in the progress of myogenesis underlying transcriptional regulation of SMAD2 and SMAD4 had been clarified. The result showed the inhibition between SMAD2 and SMAD4, which promotes and inhibits bovine myoblast differentiation, respectively. Further, the characterization of promoter region of SMAD2 and SMAD4 was analyzed, and identified C/EBPβ directly bound to the core region of both SMAD2 and SMAD4 genes promoter and stimulated the transcriptional activity. However, C/EBPβ has lower expression in myoblasts which plays vital function in the transcriptional networks controlling adipogenesis, while the overexpression of C/EBPβ gene in myoblasts significantly increased SMAD2 and SMAD4 gene expression, induced the formation of lipid droplet in bovine myoblasts, and promoted the expression of adipogenesis-specific genes. Collectively, our results showed that C/EBPβ may play an important role in the trans-differentiation and dynamic equilibrium of myoblasts into adipocyte cells via promoting an increase in SMAD2 and SMAD4 gene levels. These results will provide an important basis for further understanding of the TGFβ pathway and C/EBPβ gene during myogenic differentiation.