Responses of MAC-T Cells to Inhibited Stearoyl-CoA Desaturase 1 during cis-9, trans-11 Conjugated Linoleic Acid Synthesis.

Cis-9-conjugated, trans-11-conjugated linoleic acid (CLA) is known for its positive activities on human health. The synthesis of cis-9, trans-11 CLA in mammary glands is generally thought to be catalyzed by stearoyl-CoA desaturase 1 (SCD1), but this has not been rigorously established. In this study, we hypothesized that the inhibition of SCD1 (by CAY10566) would block the synthesis of cis-9, trans-11 CLA in bovine mammary alveolar cells (MAC-T) cells. Results showed that MAC-T cells incubated with 10 nM CAY10566 for 12 h (CAY) produced less cis-9, trans-11 CLA (p < 0.01), lower 14:1/(14:1 + 14:0)% (p < 0.01), more trans-11 18:1 (TVA) accumulation (p < 0.01), and reduced SCD1 mRNA levels (p < 0.01) compared with the control group (CON). Moreover, the mRNA abundances of sterol regulatory element-binding protein 1 [SREBPF1], acyl-CoA synthetase short-chain family member 2 [ACSS2], and lipin 1 [LPIN1] were significantly elevated when SCD1 was inhibited in the CAY group (p < 0.05). Taken together, CAY10566 inhibition of SCD1 resulted in lower cis-9, trans-11 CLA synthesis ability, and SREBF1, ACSSS2, and LPIN1 were negatively associated with SCD1. These findings not only provide the direct evidence that cis-9, trans-11 CLA synthesis is catalyzed by SCD1, but also help us understand the responses of MAC-T cells to SCD1 inhibition.