title: YES, a Src family kinase, is a proximal glucose-specific activator of cell division cycle control protein 42 (Cdc42) in pancreatic islet β cells.
abstract: Second-phase insulin secretion sustains insulin release in the face of hyperglycemia associated with insulin resistance, requiring the continued mobilization of insulin secretory granules to the plasma membrane. Cdc42, the small Rho family GTPase recognized as the proximal glucose-specific trigger to elicit second-phase insulin secretion, signals downstream to activate the p21-activated kinase (PAK1), which then signals to Raf-1/MEK/ERK to induce filamentous actin (F-actin) remodeling, to ultimately mobilize insulin granules to the plasma membrane. However, the steps required to initiate Cdc42 activation in a glucose-specific manner in β cells have remained elusive. Toward this, we identified the involvement of the Src family kinases (SFKs), based upon the ability of SFK inhibitors to block glucose-stimulated Cdc42 and PAK1 activation events as well as the amplifying pathway of glucose-stimulated insulin release, in MIN6 β cells. Indeed, subsequent studies performed in human islets revealed that SFK phosphorylation was induced only by glucose and within 1 min of stimulation before the activation of Cdc42 at 3 min. Furthermore, pervanadate treatment validated the phosphorylation event to be tyrosine-specific. Although RT-PCR showed β cells to express five different SFK proteins, only two of these, YES and Fyn kinases, were found localized to the plasma membrane, and of these two, only YES kinase underwent glucose-stimulated tyrosine phosphorylation. Immunodetection and RNAi analyses further established YES kinase as a proximal glucose-specific signal in the Cdc42-signaling cascade. Identification of YES kinase provides new insight into the mechanisms underlying the sustainment of insulin secretion via granule mobilization/replenishment and F-actin remodeling.
authors.affiliation: Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202.
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Yoder
authors.affiliation: Department of Cellular and Integrative Physiology, and Indiana University School of Medicine, Indianapolis, Indiana 46202.
authors.forename: Stacey L
authors.initials: SL
authors.lastname: Dineen
authors.affiliation: Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202.
authors.forename: Zhanxiang
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Cellular and Integrative Physiology, and Indiana University School of Medicine, Indianapolis, Indiana 46202; Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202. Electronic address: dthurmon@iu.edu.
authors.forename: Debbie C
authors.initials: DC
authors.lastname: Thurmond
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000502:physiology; D005947:Glucose / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000235:genetics / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics / Q000378:metabolism; D051575:Proto-Oncogene Proteins c-yes / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013997:Time Factors; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D054462:p21-Activated Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D007328:Insulin; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; D051575:Proto-Oncogene Proteins c-yes; C489834:YES1 protein, human; C515903:PAK1 protein, human; D054462:p21-Activated Kinases; D020764:cdc42 GTP-Binding Protein; D005947:Glucose
keywords: Actin; Cdc42; Insulin Secretion; Pancreatic Islets; Src