Beta-Mecaptoethanol Suppresses Inflammation and Induces Adipogenic Differentiation in 3T3-F442A Murine Preadipocytes

Abstract

Preadipocytes are present in adipose tissues throughout adult life that can proliferate and differentiate into mature adipocytes in response to environmental cues. Abnormal increase in adipocyte number or size leads to fat tissue expansion. However, it is now recognized that adipocyte hypertrophy is a greater risk factor for metabolic syndrome whereas fat tissue that continues to produce newer and smaller fat cells through preadipocyte differentiation is “metabolically healthy”. Because adipocyte hypertrophy is often associated with increased oxidant stress and low grade inflammation, both are linked to disturbed cellular redox, we tested how preadipocyte differentiation may be regulated by beta-mercaptoethanol (BME), a pharmacological redox regulator and radical scavenger, using murine 3T3-F442A preadipocytes as the cell model. Effects of BME on adipogenesis were measured by microphotography, real-time PCR, and Western analysis. Our data demonstrated that preadipocyte differentiation could be regulated by extracellular BME. At an optimal concentration, BME enhanced expression of adipogenic gene markers and lipid accumulation. This effect was associated with BME-mediated down-regulation of inflammatory cytokine expression during early differentiation. BME also attenuated TNFalpha-induced activation of NFkappaB in differentiating preadipocytes and partially restored TNFalpha-mediated suppression on adipogenesis. Using a non-adipogenic HEK293 cell line transfected with luciferase reporter genes, we demonstrated that BME reduced basal and TNFalpha-induced NFkappaB activity and increased basal and ciglitazone-induced PPARgamma activity; both may contribute to the pro-adipogenic effect of BME in differentiating F442A preadipocytes.

Effects of thiol antioxidant β-mercaptoethanol on diet-induced obese mice

“…As shown in Figure 4A, expression of phosphorylated (activated) forms of NFκB-p65 and -p50 subunits were both reduced in BME-treated animals. This is consistent with the reduction in cytokine mRNA (Figure 3B) and in agreement with our prior report that BME inhibits NFκB activity in cultured pre-adipocytes 28 . In addition, we measured the fat tissue expression of mitochondrial uncoupling proteins (UCPs), the established ROS-induced molecular targets 39 .…”

“…The leftover fat for the epididymal depot was pulverized in liquid nitrogen and well mixed before sampling for RNA and protein analysis. RNA isolation and real-time quantitative polymerase chain reaction (RT-qPCR) were performed as described previously 28 . The PCR primer sequences are listed in Table 1.…”

Adiponectin promotes preadipocyte differentiation via the PPARγ pathway

“…It has previously been reported that elevated proinflammatory cytokine levels mediate insulin resistance, type II diabetes and cardiovascular disease (21). Inflammatory cytokines, including MCP-1, IL-6, IL-8 and TNF-α, which are secreted by adipose tissue, are able to increase infiltration of local immune cells and aggravate chronic inflammation in adipose tissue, thus leading to adipose tissue dysfunction and metabolic disorders (22,23).…”

Conservation of Binding Epitopes for Monoclonal Antibodies on the Rabies Virus Glycoprotein

“…Lopinavir may inhibit adipocyte differentiation in vitro but the in vivo results are inconclusive [19][20][21][22]8,9]. As shown in Figure 3A (upper panel), Kaletra did not change inguinal fat expression of (Peroxisome proliferator-activated receptor gamma) PPARγ2 and Ccaat-enhancer-binding proteins (C/EBPα), both are master transcription factors that coordinately regulate adipogenesis [23] or their downstream target adiponectin but reduced expression of inflammatory cytokine TNFα, a cytokine known to inhibit adipogenesis [24]. In epididymal fat, Kaletra moderately increased expression of PPARγ2 and adiponectin and simultaneously reduced expression of TNFα ( Figure 3A, lower panel).…”