Secreted Nucleobindin-2 Inhibits 3T3-L1 Adipocyte Differentiation

Abstract

Nucleobindin-2 is a 420 amino acid EF-hand Ca2+ binding protein that can be further processed to generate an 82 amino terminal peptide termed Nesfatin-1. To examine the function of secreted Nucleobindin-2 in adipocyte differentiation, cultured 3T3-L1 cells were incubated with either 0 or 100 nM of GST, GST-Nucleobindin-2, prior to and during the initiation of adipocyte differentiation. Nucleobindin-2 treatment decreased neutral lipid accumulation (Oil-Red O staining) and expression of several marker genes for adipocyte differentiation (PPARγ, aP2, and adipsin). When Nucleobindin-2 was constitutively secreted into cultured medium, cAMP content and insulin stimulated CREB phosphorylation were significantly reduced. On the other hand, intracellularly overexpressed Nucleobindin-2 failed to affect cAMP content and CREB phosphorylation. Taken together, these data indicate that secreted Nucleobindin-2 is a suppressor of adipocyte differentiation through inhibition of cAMP production and insulin signal.

Nesfatin-1 promotes brown adipocyte phenotype

“…This finding extends the action of nesfatin-1 to brown adipocytes and provides further evidence supporting its critical role in the regulation of lipid homeostasis. Consistent with this observation, previous studies have demonstrated that nesfatin-1 inhibits lipid accumulation in 3T3-L1 cells16 and hepatocytes17, as well as reduces circulating fatty acid levels in diet-induced obese mice1718. NUCB2/nesfatin-1 is expressed abundantly in the X/A like cells of gastric mucosa and may be released into the circulation to exert actions in both central and peripheral tissues.…”

Peripheral Effects of Nesfatin-1 on Glucose Homeostasis

“…In addition to its originally identified function to inhibit dark cycle food intake, nesfatin-1 exhibits a broad array of actions, ranging from effects on glucose metabolism [11], inhibition of gastric acid secretion [15] and gastrointestinal motility [16], control of fluid and electrolyte homeostasis [17], inhibition of adipogenesis [18], counteracting NO-dependent vasodilation [19], to cardio-protection against ischemia/reperfusion injury [20]. Among these functions, the effects of nesfatin-1 on glucose homeostasis and its potential mechanisms remain controversial.…”

Regulation of NUCB2/nesfatin-1 production in rat's stomach and adipose tissue is dependent on age, testosterone levels and lactating status

“…3A). Different from that found in gastric mucosa, the NUCB2 detection by western blot in adipose tissue presented one only band at 50 kDa as previously described in the bibliography for this tissue with the same antibody Ramanjaneya et al, 2010;Tagaya et al, 2012). Conversely to protein expression the NUCB2 mRNA expression peak was at 6 weeks of age (2 weeks old: 1.01 ± 0.06, 4 weeks old: 1.31 ± 0.17, 6 weeks old: 1.50 ± 0.14 and 8 weeks old: 0.98 ± 0.06 arbitrary units; **p < 0.01) (Fig.…”