Glucose Utilization, Lipid Metabolism and BMP-Smad Signaling Pathway of Porcine Intramuscular Preadipocytes Compared with Subcutaneous Preadipocytes

Abstract

Background/Aims: We previously reported that porcine intramuscular (i.m.) preadipocytes were different from subcutaneous (s.c.) preadipocytes on cell differentiation and lipid accumulation, but the underlying mechanisms remained unknown. The paper aims to investigate the underlying mechanisms by comparing the differences between i.m. and s.c. preadipocytes in glucose utilization, lipid metabolism, and the role of BMP signaling pathway. Methods: Experiments were performed in porcine primary i.m. and s.c. preadipocytes in culture. The mRNA and protein expression patterns were determined respectively by Quantitative real-time PCR and Western blot. Cytosolic triglycerides were examined by triglyceride assay. Results: The i.m. preadipocytes consumed more glucose by expression of GLUT1 and s.c. preadipocytes mainly utilized exogenic fatty acids for lipid synthesis by expression of LPL and FAT. Meanwhile, the expression of genes related to lipogenesis and lipolysis in s.c. preadipocytes increased more quickly than those in i.m. preadipocytes. The expression patterns of the genes involved in BMP-Smad signaling pathway were consistent with those of the genes participated in adipocytes differentiation in both i.m. and s.c. preadipocytes. Exogenous BMP2 significantly increased, whereas Noggin and Compound C, remarkablely decreased the triglycerides content in i.m. preadipoytes, without affecting s.c. preadipocytes. BMP2 shRNA significantly reduced the mRNA levels of the downstream genes of BMP-Smad signaling pathway and PPARγ in both i.m. and s.c. preadipocytes. Conclusion: These findings suggested that the differentiation and lipid accumulation differences between i.m. and s.c. preadipocytes might be caused by the different manners of glucose utilization, lipid metabolism and the BMP-Smad signaling pathway. The special feature of i.m. adipocytes implied that these cells might be a potential target for treatment of diabetes.

Comparison of the adipogenesis in intramuscular and subcutaneous adipocytes from Bamei and Landrace pigs

“…Diets greater in starch promote IM fat deposition relative to SC deposition (Choat et al 2003). Some molecular events in the development of IM fat have been recently revealed by differential display RT-PCR and microarray assays, using longissimus dorsi muscle (LM) samples in bovine (Lee et al 2007;Wang et al 2009) and in porcine (Wang et al 2013b;Zhou et al 2010). These results indicated that the development, lipid content, and lipid metabolism are different in adipocyte from IM and SC sources or between breeds.…”

“…The potential for cellular development of adipocytes is believed to be fixed relatively early in life and to change thereafter in either the size or number of cells that occur in proportion to the initial cell number (Kirkland and Dobson 1997;Caserta et al 2001;Pethick et al 2004). Evidence has now accumulated to indicate that adipocytes isolated from SC or IM adipose tissues display distinct patterns in proliferation and differentiation (Wang et al 2013b;Hauner and Entenmann 1991;Van Harmelen et al 2004;Djian et al 1983;Kirkland et al 1990), and metabolic activity (Kirkland et al 1996;Gardan et al 2006Gardan et al , 2007Smith et al 1998) in some species. May et al (1994) showed that pre-adipocytes of Wagyu steer proliferate more actively than the cells of Angus steer.…”

Genome-Wide Analysis of mRNAs and lncRNAs of Intramuscular Fat Related to Lipid Metabolism in Two Pig Breeds

“…In addition, human health problems caused by obesity are attracting more attention. It has been demonstrated that intramuscular adipocytes prefer to use glucose and obesity can lead to intramuscular lipid accumulation that is associated with several metabolic disorders including insulin resistance and type II diabetes [2,3]. Importantly, pig is anatomically and physiologically similar to human, thus it can be used as a good medical model for studying lipid metabolic disease [4][5][6].…”

Mulberry 1-Deoxynojirimycin Inhibits Adipogenesis by Repression of the ERK/PPARγ Signaling Pathway in Porcine Intramuscular Adipocytes

“…18 It is generally considered that IMF may have a positive influence on meat quality including tenderness, juiciness, and flavor. 19,20 However, negative effects of IMF on human health have been reported.…”