LKB1 Regulates Goat Intramuscular Adipogenesis Through Focal Adhesion Pathway

Abstract

Intramuscular fat (IMF) deposition is one of the most important factors to affect meat quality in livestock and induce insulin resistance and adverse metabolic phenotypes for humans. However, the key regulators involved in this process remain largely unknown. Although liver kinase B1 (LKB1) was reported to participate in the development of skeletal muscles and classical adipose tissues. Due to the specific autonomic location of intramuscular adipocytes, deposited between or within muscle bundles, the exact roles of LKB1 in IMF deposition need further verified. Here, we cloned the goat LKB1 coding sequence with 1,317 bp, encoding a 438 amino acid peptide. LKB1 was extensively expressed in detected tissues and displayed a trend from decline to rise during intramuscular adipogenesis. Functionally, knockdown of LKB1 by two individual siRNAs enhanced the intramuscular preadipocytes differentiation, accompanied by promoting lipid accumulation and inducing adipogenic transcriptional factors and triglyceride synthesis-related genes expression. Conversely, overexpression of LKB1 restrained these biological signatures. To further explore the mechanisms, the RNA-seq technique was performed to compare the difference between siLKB1 and the control group. There were 1,043 differential expression genes (DEGs) were screened, i.e., 425 upregulated genes and 618 downregulated genes in the siLKB1 group. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis predicted that the DEGs were mainly enriched in the focal adhesion pathway and its classical downstream signal, the PI3K-Akt signaling pathway. Specifically, knockdown of LKB1 increased the mRNA level of focal adhesion kinase (FAK) and vice versa in LKB1-overexpressed cells, a key component of the activated focal adhesion pathway. Convincingly, blocking this pathway by a specific FAK inhibitor (PF573228) rescued the observed phenotypes in LKB1 knockdown adipocytes. In conclusion, LKB1 inhibited goat intramuscular adipogenesis through the focal adhesion pathway. This work expanded the genetic regulator networks of IMF deposition and provided theoretical support for improving human health and meat quality from the aspect of IMF deposition.

A genome-wide landscape of mRNAs, lncRNAs, circRNAs and miRNAs during intramuscular adipogenesis in cattle

“…We will explore the molecular mechanisms of these genes in the future. Meanwhile, we found that DEMs, DECs and DELs were significantly enriched in the Focal adhesion and the ECM-receptor-interaction pathways, which was consistent with the findings in goat and chicken IMF [ 42 , 43 ]. Studies have found that focal adhesion kinase (FAK) and ECM-receptor interactions can regulate intramuscular adipogenesis in goats and chickens [ 43 , 44 ].…”

Screening of key miRNAs related with the differentiation of subcutaneous adipocytes and the validation of miR-133a-3p functional significance in goats

“…Studies have shown that the FAK participated in adipocyte differentiation, and its cleavage by calpain was required to fulfill the final maturation of adipocytes [ 25 ]. Study had also shown that liver kinase B1 (LKB1) inhibited goat intramuscular adipogenesis through the FAK pathway, blocking this pathway rescued the observed phenotypes in LKB1 knockdown adipocytes [ 26 ]. MAPK phosphatase-1 (MKP-1) plays an essential role in adipocyte differentiation through down-regulation of p42/p44 MAPK activity [ 27 ].…”

Key circRNAs from goat: discovery, integrated regulatory network and their putative roles in the differentiation of intramuscular adipocytes

“…Two circRNAs, circ_0005870 and circ_0000946, were found existed in both focal adhesion [ 24 , 25 ] and PI3K-Akt signaling pathways [ 11 , 26 ] in this study, which given a great possibility of their functions in adipocyte differentiation. Therefore, we further performed prediction analysis to find the potential target genes of miRNAs that interacting with these two circRNAs.…”