Effects of Free Fatty Acids with Different Chain Lengths and Degrees of Saturability on the Milk Fat Synthesis in Primary Cultured Bovine Mammary Epithelial Cells

How
short-chain fatty acids (FAs) affect cell membrane morphology and
milk fat biosynthesis in mammary epithelial cells (MECs) is yet unclear.
This study investigated the primary bovine MEC response to different
FAs. We observed that the cell surface ultrastructures were influenced
by chain length and degree of saturability of FAs. The CD36, FATP1, and FABP3 gene expression
was affected independent of the type of FA. FASN, LPIN1, PPARα, and PPARγ transcripts were more sensitive to the short-chain FAs (acetic and
β-hydroxybutyric acids). Furthermore, short-chain FAs inclined
to regulate FA degradation-, elongation-, and metabolism-associated
pathways, while long-chain FAs (stearic and trans-10,cis-12 conjugated linolenic acids) modulated
extracellular matrix–receptor interaction-, transcriptional
misregulation-, microRNA-, and ribosome biogenesis-related pathways.
However, triacylglycerol accumulation in the cytoplasm was not changed
by all of the FAs. Overall, FAs with different chain lengths and degrees
of saturability could differentially alter primary bovine MEC cell
morphology and influence protein profiles involved in milk fat synthesis
pathways.

短链脂肪酸（short-chain fatty acids, FAs）如何影响乳腺上皮细胞（mammary epithelial cells, MECs）的细胞膜形态与乳脂肪生物合成，目前仍不明确。本研究探究了原代牛乳腺上皮细胞对不同脂肪酸的应答反应。研究观察到，细胞表面超微结构受脂肪酸碳链长度与饱和程度的影响。CD36、FATP1及FABP3的基因表达水平不受脂肪酸种类的调控。FASN、LPIN1、PPARα与PPARγ的转录本对短链脂肪酸（乙酸与β-羟基丁酸）更为敏感。此外，短链脂肪酸倾向于调控脂肪酸降解、延伸及代谢相关通路；而长链脂肪酸（long-chain FAs，即硬脂酸与反-10,顺-12共轭亚麻酸）则调控细胞外基质-受体互作、转录失调、微小RNA（microRNA）及核糖体生物发生相关通路。不过，所有受试脂肪酸均未改变细胞质内三酰甘油的积累量。综上，不同碳链长度与饱和程度的脂肪酸可差异化改变原代牛乳腺上皮细胞的形态，并影响乳脂肪合成通路相关的蛋白谱。