1. Recruiting Secretory Vesicles with DAG and Munc13-1
Claudia S. Bauer, Robert J. Woolley, Anja G. Teschemacher, and Elizabeth P. Seward
This week, Bauer et al. combined voltage-clamp recordings with membrane capacitance measurements to examine modulation of secretion in bovine chromaffin cells. Their goal was to determine whether Gq-protein-coupled receptors (GqPCRs), specifically H1 histamine receptors, regulate Munc131, a protein that binds diacylglycerol (DAG) and facilitates the priming of vesicles for release. istamine decreased current through voltage-gated calcium channels by a well described direct G-protein modulation, yet the capacitance associated with stimulus-evoked secretion increased markedly. Using a double pulse depolarization protocol, the authors found that histamine increased the size of the readily releasable pool (RRP) of vesicles, and specifically increased priming of the immediately releasable pool that are positioned near calcium channels. Expression of a DAG-insensitive mutant form of Munc13-1 abolished the histamine-induced potentiation of secretion. The results define a signaling pathway leading from GqPCRs to DAG to Munc131 that can enhance vesicle priming and exocytosis.
2. DISC1 Complexes in Axonal Elongation
Tomoyasu Shinoda, Shinichiro Taya, Daisuke Tsuboi, Takao Hikita, Reiko Matsuzawa, Setsuko Kuroda, Akihiro Iwamatsu, and Kozo Kaibuchi and Shinichiro Taya, Tomoyasu Shinoda, Daisuke Tsuboi, Junko Asaki, Kumiko Nagai, Takao Hikita, Setsuko Kuroda, Keisuke Kuroda, Mariko Shimizu, Shinji Hirotsune, Akihiro Iwamatsu, and Kozo Kaibuchi
This week, two papers from the same group investigated Disrupted-In-Schizophrenia-1 (DISC1), a candidate gene in some cases of schizophrenia. The results suggest that DISC1 is in the cargo-hauling business. Taya et al. examined the association between DISC1 and theNUDEL(NudE-like)/lissencephaly-1 (LIS1)/143-3
Contact: Sara Harris
Society for Neuroscience