title: Nucleobindin-2 is a positive modulator of EGF-dependent signals leading to enhancement of cell growth and suppression of adipocyte differentiation.
abstract: Nucleobindin-2 is a 420-amino-acid EF-hand calcium-binding protein that undergoes proteolytic processing to generate an 82-amino-acid amino-terminal peptide termed nesfatin-1. To determine whether nucleobindin-2 has any biological function, nucleobindin-2 was either overexpressed or knocked down by short hairpin RNA in cultured CHO cells expressing the human insulin and epidermal growth factor (EGF) receptors (CHO/IE) and in 3T3-L1 cells. Reduction in nucleobindin-2 expression inhibited EGF-stimulated MAPK kinase (S217/S221) and Erk phosphorylation (T202/Y204). In contrast, there was no significant effect on EGF-stimulated EGF receptor phosphorylation, EGF receptor internalization, or 52-kDa Shc and c-Raf phosphorylation. Although kinase suppressor of Ras-1 and protein phosphatase 2A expression was not changed, intracellular calcium concentrations and PP2A activity was significantly increased in nucleobindin-2 knocked-down cells. Concomitant with these alterations in EGF-stimulated signaling, cell proliferation was significantly reduced in nucleobindin-2 knocked-down cells. Moreover, reduced nucleobindin-2 expression in 3T3-L1 preadipocytes resulted in a greater extent of 3T3-L1 cell adipocyte differentiation. Taken together, these data indicate that nucleobindin-2 regulates EGF-stimulated MAPK kinase/Erk signaling, cell proliferation, and adipocyte differentiation.
authors.affiliation: Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, 3-39-15 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tagaya
authors.forename: Atsuko
authors.initials: A
authors.lastname: Miura
authors.forename: Shuichi
authors.initials: S
authors.lastname: Okada
authors.forename: Kihachi
authors.initials: K
authors.lastname: Ohshima
authors.forename: Masatomo
authors.initials: M
authors.lastname: Mori
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology*; D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000096:biosynthesis*; D002454:Cell Differentiation; D049109:Cell Proliferation; D006224:Cricetinae; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D018274:Electroporation; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D000080866:Nucleobindins; D054648:Protein Phosphatase 2 / Q000378:metabolism; D011972:Receptor, Insulin / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; C000630650:NUCB2 protein, human; D009419:Nerve Tissue Proteins; C000630651:Nucb1 protein, mouse; C000630652:Nucb1 protein, rat; D000080866:Nucleobindins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D011972:Receptor, Insulin; C514014:Ppp2ca protein, rat; D054648:Protein Phosphatase 2; D002118:Calcium