| First Author | Wuttke A | Year | 2016 |
| Journal | J Biol Chem | Volume | 291 |
| Issue | 29 | Pages | 14986-95 |
| PubMed ID | 27226533 | Mgi Jnum | J:328025 |
| Mgi Id | MGI:7335149 | Doi | 10.1074/jbc.M115.698456 |
| Citation | Wuttke A, et al. (2016) Autocrine Signaling Underlies Fast Repetitive Plasma Membrane Translocation of Conventional and Novel Protein Kinase C Isoforms in beta Cells. J Biol Chem 291(29):14986-95 |
| abstractText | PKC signaling has been implicated in the regulation of many cell functions, including metabolism, cell death, proliferation, and secretion. Activation of conventional and novel PKC isoforms is associated with their Ca(2+)- and/or diacylglycerol (DAG)-dependent translocation to the plasma membrane. In beta cells, exocytosis of insulin granules evokes brief (<10 s) local DAG elevations ("spiking") at the plasma membrane because of autocrine activation of P2Y1 purinoceptors by ATP co-released with insulin. Using total internal reflection microscopy, fluorescent protein-tagged PKCs, and signaling biosensors, we investigated whether DAG spiking causes membrane recruitment of PKCs and whether different classes of PKCs show characteristic responses. Glucose stimulation of MIN6 cells triggered DAG spiking with concomitant repetitive translocation of the novel isoforms PKCdelta, PKC, and PKCeta. The conventional PKCalpha, PKCbetaI, and PKCbetaII isoforms showed a more complex pattern with both rapid and slow translocation. K(+) depolarization-induced PKC translocation entirely mirrored DAG spiking, whereas PKCbetaI translocation showed a sustained component, reflecting the subplasma membrane Ca(2+) concentration ([Ca(2+)]pm), with additional effect during DAG spikes. Interference with DAG spiking by purinoceptor inhibition prevented intermittent translocation of PKCs and reduced insulin secretion but did not affect [Ca(2+)]pm elevation or sustained PKCbetaI translocation. The muscarinic agonist carbachol induced pronounced transient PKCbetaI translocation and sustained recruitment of PKC. When rise of [Ca(2+)]pm was prevented, the carbachol-induced DAG and PKC responses were somewhat reduced, but PKCbetaI translocation was completely abolished. We conclude that exocytosis-induced DAG spikes efficiently recruit both conventional and novel PKCs to the beta cell plasma membrane. PKC signaling is thus implicated in autocrine regulation of beta cell function. |
