A novel IRS-1-associated protein, DGKζ regulates GLUT4 translocation in 3T3-L1 adipocytes

Abstract

Insulin receptor substrates (IRSs) are major targets of insulin receptor tyrosine kinases. Here we identified diacylglycerol kinase zeta (DGKζ) as an IRS-1-associated protein, and examined roles of DGKζ in glucose transporter 4 (GLUT4) translocation to the plasma membrane. When DGKζ was knocked-down in 3T3-L1 adipocytes, insulin-induced GLUT4 translocation was inhibited without affecting other mediators of insulin-dependent signaling. Similarly, knockdown of phosphatidylinositol 4-phosphate 5-kinase 1α (PIP5K1α), which had been reported to interact with DGKζ, also inhibited insulin-induced GLUT4 translocation. Moreover, DGKζ interacted with IRS-1 without insulin stimulation, but insulin stimulation decreased this interaction. Over-expression of sDGKζ (short-form DGKζ), which competed out DGKζ from IRS-1, enhanced GLUT4 translocation without insulin stimulation. Taking these results together with the data showing that cellular PIP5K activity was correlated with GLUT4 translocation ability, we concluded that IRS-1-associated DGKζ prevents GLUT4 translocation in the absence of insulin and that the DGKζ dissociated from IRS-1 by insulin stimulation enhances GLUT4 translocation through PIP5K1α activity.

40 YEARS OF IGF1: IGF1 receptor signaling pathways

“…On the other hand, DGKζ was isolated as an IRS-1-binding protein. The interaction was dissociated by insulin stimulation, but the interaction of DGKζ with IRS-2 was not observed (Liu et al 2016). These observations might be clues to evaluate the functional differences between IRS-1 and IRS-2.…”

“…However, we have shown that IRS-1 and IRS-2 interact with many proteins without hormone stimulation in a phosphotyrosineindependent manner (Fukushima et al 2011a. Isolation of IRS-associated proteins revealed that IRS-1-and IRS-2-associated protein complexes contained quite different proteins (Hakuno et al 2007, Fukushima et al 2011a,b, 2015, Yoshihara et al 2012, Yoneyama et al 2013, Ando et al 2015, Liu et al 2016. IRS-1 and IRS-2 have a unique sequence in the C-terminal domain except for the putative tyrosine residues, which are phosphorylated by active receptor.…”

SOX2 protein biochemistry in stemness, reprogramming, and cancer: the PI3K/AKT/SOX2 axis and beyond

“…Triggered by insulin or amino acid availability on the cell surface, the PI3K/AKT axis converts information on the current bioavailability of these metabolites into downstream effector functions within the cell [68][69][70][71][72]. In response to insulin for example, PI3K/ AKT modulates cellular glucose uptake (more actually the cell surface expression of individual glucose transporters, GLUT) involving AS160, DGKzeta, and PIP5K proteins [73,74]. In response to amino acids such as glutamate, PI3K/AKT stimulates mTORC1, the mammalian target of rapamycin complex 1, that induces phospho-activation of ribosomal protein S6 (RPS6) by S6 kinase (S6K1) [75,76] and a release of eIF4E from its inhibitor 4E-BP1 [77,78] to launch protein synthesis.…”

Analytical Method for Diacylglycerol Kinase ζ Activity in Cells Using Protein Myristoylation and Liquid Chromatography–Tandem Mass Spectrometry

“…In neuroblastoma cells, DGKζ partly localizes at the plasma membrane during retinoic acid‐induced differentiation (Mizuno, S., et al unpublished work). Moreover, insulin receptor (Liu et al, ) and TCR (Rincon et al, ) stimulation induce DGKζ translocation to the plasma membrane. Therefore, the random membrane localization of Myr‐AcGFP‐DGKζ might cause the production of broad PtdOH species.…”

“…It was reported that DGKζ deficiency leads to reduced adiposity and protection against insulin resistance (Benziane et al, ). In addition, DGKζ associates with an insulin receptor substrate‐1 and regulates GLUT‐4 translocation in adipocytes (Liu et al, ). Moreover, it was reported that the action of DGKζ attenuates cell proliferation by reducing nuclear DAG levels (Topham et al, ).…”