Characterization of methionine adenosyltransferase 2β gene expression in skeletal muscle and subcutaneous adipose tissue from obese and lean pigs

摘要

Methionine adenosyltransferase (MAT) catalyzes the biosynthesis of S-adenosylmethionine. Two genes (MAT1A and MAT2A) encode for the catalytic subunit of MAT, while a third gene (MAT2β) encodes for a regulatory subunit (MAT II β) that regulates the activity of the MAT2A-encoded isoenzyme and intracellular S-adenosylmethionine levels. Our previous work identified MAT2β as a candidate gene for intramuscular fat (IMF) deposition in porcine skeletal muscle by microarray technology. Here, we cloned porcine MAT2β cDNA and compared its expression pattern in subcutaneous adipose tissue and skeletal muscle from obese (Rongchang Breed) and lean (Pig Improvement Company, PIC) pigs (n = 6). The porcine MAT2β cDNA was 1,800 bp long and encodes for 334 amino acids sharing high similarity with other species. MAT2β is expressed at a higher level in liver and duodenum, followed by the stomach, fat and longissinus dorsi muscle. As expected, both subcutaneous fat content and IMF content were higher in obese than in lean pigs (both P < 0.01). MAT2β mRNA abundance was lower in both subcutaneous adipose tissue and skeletal muscle in obese pigs compared with lean pigs (both P < 0.01). MAT II β protein content was lower in skeletal muscle in obese than in lean pigs (P < 0.05), whereas the opposite was observed in subcutaneous adipose tissue (P < 0.01). These data demonstrated an obesity-related expression variation of the MAT II β subunit in skeletal muscle and adipose tissue in pigs, and suggest a novel role for the MAT2β gene in regulation of IMF deposition in skeletal muscle.