Dataset Information

Munc13-4 functions as a Ca²⁺ sensor for homotypic secretory granule fusion to generate endosomal exocytic vacuoles.

ABSTRACT: Munc13-4 is a Ca²⁺-dependent SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor)- and phospholipid-binding protein that localizes to and primes secretory granules (SGs) for Ca²⁺-evoked secretion in various secretory cells. Studies in mast cell-like RBL-2H3 cells provide direct evidence that Munc13-4 with its two Ca²⁺-binding C2 domains functions as a Ca²⁺ sensor for SG exocytosis. Unexpectedly, Ca²⁺ stimulation also generated large (>2.4 ?m in diameter) Munc13-4⁺/Rab7⁺/Rab11⁺ endosomal vacuoles. Vacuole generation involved the homotypic fusion of Munc13-4⁺/Rab7⁺ SGs, followed by a merge with Rab11⁺ endosomes, and depended on Ca²⁺ binding to Munc13-4. Munc13-4 promoted the Ca²⁺-stimulated fusion of VAMP8-containing liposomes with liposomes containing exocytic or endosomal Q-SNAREs and directly interacted with late endosomal SNARE complexes. Thus Munc13-4 is a tethering/priming factor and Ca²⁺ sensor for both heterotypic SG-plasma membrane and homotypic SG-SG fusion. Total internal reflection fluorescence microscopy imaging revealed that vacuoles were exocytic and mediated secretion of ?-hexosaminidase and cytokines accompanied by Munc13-4 diffusion onto the plasma membrane. The results provide new molecular insights into the mechanism of multigranular compound exocytosis commonly observed in various secretory cells.

SUBMITTER: Woo SS

PROVIDER: S-EPMC5349786 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Munc13-4 functions as a Ca2+ sensor for homotypic secretory granule fusion to generate endosomal exocytic vacuoles.

Woo Sang Su SS James Declan J DJ Martin Thomas F J TF

Molecular biology of the cell 20170118 6

Munc13-4 is a Ca2+-dependent SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor)- and phospholipid-binding protein that localizes to and primes secretory granules (SGs) for Ca2+-evoked secretion in various secretory cells. Studies in mast cell-like RBL-2H3 cells provide direct evidence that Munc13-4 with its two Ca2+-binding C2 domains functions as a Ca2+ sensor for SG exocytosis. Unexpectedly, Ca2+ stimulati ...[more]

PMID: 28100639

Similar Datasets

Project description:Objective: As a well-known traditional Chinese medicine formula prescribed by academician Ke-ji Chen, Qingda granule (QDG) lowered the blood pressure of spontaneously hypertensive rats and attenuated hypertensive cardiac remodeling and inflammation. However, its functional role and underlying mechanisms on hypertensive vascular function remain largely unclear. This study aims to assess the effects of QDG treatment on Angiotensin II- (AngII-) induced hypertension and vascular function and explore its underlying mechanisms both in vitro and in vivo. Methods: In an in vivo study, 25 male C57BL/6 mice were randomly divided into five groups, including Control, AngII, AngII + QDG-L, AngII + QDG-M, and AngII + QDG-H groups (n = 5 for each group). Mice in AngII and AngII + QDG-L/-M/-H groups were infused with AngII (500 ng/kg/min), while in the Control group, they were infused with saline. Mice in AngII + QDG were intragastrically given different concentrations of QDG (0.5725, 1.145, or 2.29 g/kg/day), while in Control and AngII groups, they were intragastrically given equal volumes of double distilled water for 2 weeks. Blood pressure was determined at 0, 1, and 2 weeks of treatment. Ultrasound was used to detect the pulse wave velocity (PWV) and HE staining to detect the pathological change of the abdominal aorta. RNA sequencing (RNA-seq) was performed to identify the differentially expressed transcripts (DETs) and related signaling pathways. IHC was used to detect the expression of p-ERK in the abdominal aorta. Primary isolated rat vascular smooth muscle cells (VSMCs) were used to assess the cellular Ca2+ release and activation of the ERK pathway by confocal microscope and western blotting analysis, respectively. Results: QDG treatment significantly alleviated the elevated blood pressure, the PWV, and the thickness of the abdominal aorta in AngII-induced hypertensive mice. RNA-seq and KEGG analyses identified 1,505 DETs and multiple enriched pathways (including vascular contraction and calcium signaling pathway) after QDG treatment. Furthermore, confocal microscope showed that QDG treatment partially attenuated the increase of Ca2+ release with the stimulation of AngII in cultured VSMCs. In addition, IHC and western blotting indicated that QDG treatment also partially alleviated the increase of phospho-ERK levels in abdominal aorta tissues of mice and cultured VSMCs after the infusion or stimulation of AngII. Conclusion: QDG treatment attenuated the elevation of blood pressure, abdominal aorta dysfunction, pathological changes, Ca2+ release, and activation of the ERK signaling pathway.

Dataset Information

Munc13-4 functions as a Ca²⁺ sensor for homotypic secretory granule fusion to generate endosomal exocytic vacuoles.

Publications

Munc13-4 functions as a Ca<sup>2+</sup> sensor for homotypic secretory granule fusion to generate endosomal exocytic vacuoles.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets