Phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) synthesis is required for calcium-dependent exocytosis in neurosecretory cells. We developed a PtdIns(4,5)P2 bead pulldown strategy combined with subcellular fractionation to identify endogenous chromaffin granule proteins that interact with PtdIns(4,5)P2. We identified two synaptotagmin isoforms, synaptotagmins 1 and 7; spectrin; alpha-adaptin; and synaptotagmin-like protein 4 (granuphilin) by mass spectrometry and Western blotting. The interaction between synaptotagmin 7 and PtdIns(4,5)P2 and its functional relevance was investigated. The 45-kDa isoform of synaptotagmin 7 was found to be highly expressed in adrenal chromaffin cells compared with PC12 cells and to mainly localize to secretory granules by subcellular fractionation, immunoisolation, and immunocytochemistry. We demonstrated that synaptotagmin 7 binds PtdIns(4,5)P2 via the C2B domain in the absence of calcium and via both the C2A and C2B domains in the presence of calcium. We mutated the polylysine stretch in synaptotagmin 7 C2B and demonstrated that this mutant domain lacks the calcium-independent PtdIns(4,5)P2 binding. Synaptotagmin 7 C2B domain inhibited catecholamine release from digitonin-permeabilized chromaffin cells, and this inhibition was abrogated with the C2B polylysine mutant. These data indicate that synaptotagmin 7 C2B-effector interactions, which occur via the polylysine stretch, including calcium-independent PtdIns(4,5)P2 binding, are important for chromaffin granule exocytosis.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1074/mcp.M600430-MCP200 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Engineering covalent small molecule-RNA complexes in living cells.
Nat Chem Biol
January 2025
University of Innsbruck, Institute of Organic Chemistry and Center for Molecular Biosciences (CMBI), Innsbruck, Austria.
Covalent labeling of RNA in living cells poses many challenges. Here we describe a structure-guided approach to engineer covalent RNA aptamer-ligand complexes. The key is to modify the cognate ligand with an electrophilic handle that allows it to react with a guanine at the RNA binding site.
View Article and Find Full Text PDFALKBH5 facilitates tumor progression via an m6A-YTHDC1-dependent mechanism in glioma.
Cancer Lett
January 2025
Department of Neurosurgery Center, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282 China. Electronic address:
N-methyladenosine (m6A) methylation, is a well-known epigenetic modification involved in various biological processes, including tumorigenesis. However, the role of AlkB homolog 5 (ALKBH5), a critical component of m6A modification, remains unclear in glioma. This study investigates the function of ALKBH5 in glioma progression and its potential as a therapeutic target.
View Article and Find Full Text PDFYafN-YafO toxin-antitoxin system contributes to stress resistance and virulence of avian pathogenic Escherichia coli.
Poult Sci
January 2025
Institute of Agricultural Science and Technology Development, College of Veterinary Medicine, Yangzhou University, Yangzhou, PR China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, PR China; Key Laboratory of Avian Bioproduct Development, Ministry of Agriculture and Rural Affairs, Yangzhou, PR China; Institutes of Agricultural Science and Technology Development, Yangzhou University, Yangzhou, PR China. Electronic address:
Avian pathogenic Escherichia coli (APEC) is a major threat to the poultry industry, causing bloodstream and extraintestinal infections. Type II toxin-antitoxin (TA) systems are known to aid bacterial pathogens in adapting to stress, promoting persister cell formation, and enhancing virulence. While type II TA systems have been extensively studied in many pathogens, APEC-derived TAs have received limited attention.
View Article and Find Full Text PDFMiR8523 negatively regulates the immunity of Plutella xylostella against entomopathogenic fungus Isaria cicadae by targeting PxSpz5.
Int J Biol Macromol
January 2025
Anhui Province Key Laboratory of Integrated Pest Management on Crops, School of Plant Protection, Anhui Agricultural University, Hefei 230036, China; Key Laboratory of Agri-products Quality and Biosafety (Anhui Agricultural University), Ministry of Education, Hefei 230036, China. Electronic address:
The diamondback moth, Plutella xylostella is a notorious pest and has developed serious resistance to insecticides. Entomopathogenic fungi (EPF) have been developed as eco-friendly alternatives to insecticides. Insects rely on their immunity to defend against fungi.
View Article and Find Full Text PDFAnillin interacts with RhoA to promote tumor progression in anaplastic thyroid cancer by activating the PI3K/AKT pathway.
Endocrine
December 2024
Department of General Surgery, Nanfang Hospital, The First School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong Province, China.
Background: Anaplastic thyroid cancer (ATC) is the most aggressive thyroid malignancy and has an extremely poor prognosis, necessitating novel therapeutic strategies. This study investigated the role of anillin (ANLN) in ATC, focusing on its impact on tumor growth and metastasis through the RhoA/PI3K/AKT signaling pathway.
Methods: TCGA and GEO datasets were analyzed to identify key molecular alterations in thyroid cancer.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!