miR-130b duplex (miR-130b-3p/miR-130b-5p) negatively regulates goat intramuscular preadipocyte lipid droplets accumulation by inhibiting Krüppel-like factor 3 expression

Intramuscular lipid deposition is important for meat quality improvement. microRNAs and their target mRNAs provide a new approach for studying the mechanism of fat deposition. The present study aimed to investigate the effect of miR-130b duplex (miR-130b-5p, miR-130b-3p) and its target gene KLF3 in regulating goat intramuscular adipocyte differentiation. Goat intramuscular preadipocytes were isolated from 7-d-old male Jianzhou big-ear goats and identified by Oil red O staining after differentiation induction. miR-130b-5p and miR-130b-3p mimics or inhibitors and their corresponding controls were transfected into goat intramuscular preadipocytes, respectively, and differentiation was induced by 50μM oleic acid for 48 h. Oil red O and Bodipy staining indicated that both miR-130b-5p and miR-130b-3p can reduce lipid droplets accumulation and triglyceride (TG) content (P < 0.01). Differentiation markers C/EBPα, C/EBPβ, PPARγ, pref1, fatty acids synthesis markers ACC, FASN, DGAT1, DGAT2, AGPAT6, TIP47, GPAM, ADRP, AP2, SREBP1, and TG markers LPL, ATGL, HSL were assessed by qPCR. All the markers measured were downregulated by miR-130b-5p and miR-130b-3p analog (P < 0.01), suggesting that miR-130b inhibits goat intramuscular adipocyte adipogenic differentiation, fatty acids synthesis, and lipid lipolysis. To examine the mechanism of miR-130b duplex inhibition of lipid deposition, TargetScan, miRDB, and starBase were used to predict the potential targets, KLF3 was found to be the only one intersection. Furthermore, the 3ʹUTR of KLF3 was cloned, qPCR analysis and dual luciferase activity assay showed that both miR-130b-5p and miR-130b-3p could directly regulate KLF3 expression (P < 0.01). In addition, overexpression and interference of KLF3 were conducted, it was found that KLF3 positively regulated lipid droplets accumulation by Oil red O, Bodipy staining, and TG content detection (P < 0.01). Quantitative PCR result indicated that KLF3 overexpression promoted lipid droplets accumulation relative genes C/EBPβ, PPARγ, pref1, ACC, FASN, DGAT1, DGAT2, AGPAT6, TIP47, GPAM, ADRP, SREBP1, LPL, and ATGL expression (P < 0.01). Downregulation of KLF3 inhibited the expression of genes such as C/EBPα, C/EBPβ, PPARγ, pref1, TIP47, GPAM, ADRP, AP2, LPL, and ATGL expression (P < 0.01). Taken together, these results indicate that miR-130b duplex could directly inhibit KLF3 expression, then attenuated adipogenic and TG synthesis genes expression, thus leading to its anti-adipogenic effect.