Does miR-199a-3p Regulate Stearoyl-CoA Desaturase 1 (SCD1) in Ovine Tissues or Subcutaneous Adipocytes? Evidence for...

Stearoyl-CoA desaturase 1 (SCD1) is a key enzyme in the conversion of saturated (SFA) to monounsaturated fatty acids (MUFA) that alters the fatty acid composition of adipose tissues. We hypothesize that miR-199a-3p regulates stearoyl-CoA desaturase 1 (SCD1) expression and MUFA concentration in ovine adipose tissues and subcutaneous primary adipocytes in vitro. The objectives were to: 1) examine the relationship between miR-199a-3p and SCD1 expression, and MUFA fatty acid concentration in adipose tissues of lambs from two sire breeds, and 2) evaluate overexpression (AgomiR-199a-3p) and knockdown (AntagomiR-199a-3p) of miR-199a-3p on SCD1 mRNA expression and MUFA content in subcutaneous adipocytes in vitro.

Adipose tissue samples were collected from lambs sired by two breed types (n = 4/sire breed). miR-199a-3p and SCD1 mRNA expression, and MUFA: SFA ratio were examined in five adipose depots. Stromal vascular fraction (SVF) cells were isolated from subcutaneous adipose tissues, propagated, and used to examine overexpression (AgomiR-199a-3p) or knockdown (An-tagomiR-199a-3p) of miR-199a-3p on SCD1 expression.

Expression of miRNA-199a-3p and SCD1 mRNA differed in adipose tissues by sire breed. AgomiR-199a-3p or antagomir-199a-3p treatments did not alter SCD1 mRNA expression or MUFA content; however, the magnitude of the downregulation of miR-199a-3p with antagomiR-199a-3p treatment differed based on sire breed.

Despite the manipulation of miR-199a-3p, the lack of change in SCD1 expression or MUFA accumulation suggests that miR-199a-3p does not significantly alter SCD1 in ovine adipocytes at this level, or that regulation may occur post-transcriptionally or through different pathways. Breed-dependent changes in miRNA responsiveness and adipose gene expression may indicate that Texel-sired lambs may exhibit altered adipose tissue metabolism and muscle development.