Identification of anti-adipogenic proteins in adult bovine serum suppressing 3T3-L1 preadipocyte differentiation

Abstract

Adipocyte differentiation is a complex developmental process forming adipocytes from various precursor cells. The murine 3T3-L1 preadipocyte cell line has been most frequently used in the studies of adipocyte differentiation. Differentiation of 3T3-L1 preadipocytes includes a medium containing fetal bovine serum (FBS) with hormonal induction. In this study, we observed that differentiation medium containing adult bovine serum (ABS) instead of FBS did not support differentiation of preadipocytes. Impaired adipocyte differentiation was due to the presence of a serum protein factor in ABS that suppresses differentiation of preadipocytes. Using a proteomic analysis, alpha-2-macroglobulin and paraoxonase/arylesterase 1, which were previously shown to suppress differentiation of preadipocytes, were identified as anti-adipogenic proteins. Although their functional mechanisms have not yet been elucidated, the anti-adipogenic effects of these proteins are discussed. [BMB Reports 2013; 46(12): 582-587]

Identification of tetranectin as adipogenic serum protein

“…This observation suggests that other serum protein(s) or non-protein factor(s) regulate the function of tetranectin, which mediates the adipogenic effect of serum. In fact, ABS was shown to contain an anti-adipogenic protein(s) that suppresses adipocyte differentiation of 3T3-L1 cells, which might inhibit the adipogenic function of tetranectin [9]. In conclusion, proteins in FBS contain an adipogenic factor(s) that mediates the adipogenic effect of the serum.…”

“…Fractionation of ABSppt from ABS also separated low-abundance proteins from most high-abundance proteins that remained in ABSsup. ABSppt constituted~30% of the total ABS protein content, which showed an adipogenic effect that suppressed adipocyte differentiation of 3T3-L1 cells as previously reported [9]. Therefore, putative adipogenic proteins in FBS were screened by comparative 2D-PAGE analysis of proteins in FBSppt and ABSppt.…”

“…Serum was fractionated into supernatant (FBSsup/ABSsup) and protein precipitate (FBSppt/ABSppt) by partial protein precipitation with 10% (w/v) polyethylene glycol 8000 (PEG), as previously described [9]. Protein precipitate was dissolved in PBS and protein concentrations were determined by Bradford assay [10].…”

Promotion of lipid storage rather than of thermogenic competence by fetal versus newborn calf serum in primary cultures of brown adipocytes

“…This difference could be the result of the presence of stimulatory factors in NCS or inhibitory factors in FBS. Identification of such factors (as has been done for white adipocytes 10,11,46,47 ) and of the substances with which they interact on the target cells, can further our understanding of how circulatory factors influence brown adipose development and function. However, stimulatory factors putatively present in NCS may impede the identification of additional stimulatory factors, as differentiation may be already advanced.…”

“…More recent studies have similarly reported increased adipogenic conversion of 3T3-L1 cells cultured in FBS as compared to adult bovine serum. 10,11 FBS is thus the most commonly used serum for most cell culture systems, and it is also the most common serum of choice for adipocyte cell line cultures. Probably therefore, it is often used even for primary brown adipocyte cultures (e.g.…”