Fibronectin enhances soluble N-ethylmaleimide-sensitive factor attachment protein receptor protein expression in cultured human islets

Collagen IV-β1-Integrin Influences INS-1 Cell Insulin Secretion via Enhanced SNARE Protein Expression

β1-integrin is a key receptor that regulates cell-ECM interactions and is important in maintaining mature beta-cell functions, including insulin secretion. However, there is little reported about the relationship between ECM-β1-integrin interactions and exocytotic proteins involved in glucose-stimulated insulin secretion (GSIS). This study examined the effect of collagen IV-β1-integrin on exocytotic proteins (Munc18-1, Snap25, and Vamp2) involved in insulin secretion using rat insulinoma (INS-1) cell line. Cells cultured on collagen IV (COL IV) had promoted INS-1 cell focal adhesions and GSIS. These cells also displayed changes in levels and localization of β1-integrin associated downstream signals and exocytotic proteins involved in insulin secretion. Antibody blocking of β1-integrin on INS-1 cells cultured on COL IV showed significantly reduced cell adhesion, spreading and insulin secretion along with reduced exocytotic protein levels. Blocking of β1-integrin additionally influenced the cellular localization of exocytotic proteins during the time of GSIS. These results indicate that specific collagen IV-β1-integrin interactions are critical for proper beta-cell insulin secretion.

SNAP25 ameliorates sensory deficit in rats with spinal cord transection

Spinal cord injury causes sensory loss below the level of lesion. Synaptosomal-associated protein 25 (SNAP25) is a t-SNARE protein essential for exocytosis and neurotransmitter release, but its role in sensory functional recovery has not been determined. The aim of the present study is therefore to investigate whether SNAP25 can promote sensory recovery. By 2D proteomics, we found a downregulation of SNAP25 and then constructed two lentiviral vectors, Lv-exSNAP25 and Lv-shSNAP25, which allows efficient and stable RNAi-mediated silencing of endogenous SNAP25. Overexpression of SNAP25 enhanced neurite outgrowth in vitro and behavior response to thermal and mechanical stimuli in vivo, while the silencing of SNAP25 had the opposite effect. These results suggest that SNAP25 plays a crucial role in sensory functional recovery following spinal cord injury (SCI). Our study therefore provides a novel target for the management of SCI for sensory dysfunction.