A5091523905- Cellular transport and secretion
- Lipid Membrane Structure and Behavior
- Neuroscience and Neuropharmacology Research
- Proteoglycans and glycosaminoglycans research
- Pancreatic function and diabetes
- Ion channel regulation and function
- Receptor Mechanisms and Signaling
- Glycosylation and Glycoproteins Research
- Cell Adhesion Molecules Research
- Erythrocyte Function and Pathophysiology
- Genomics and Rare Diseases
- Genetics and Neurodevelopmental Disorders
- Neurotransmitter Receptor Influence on Behavior
- Viral Infectious Diseases and Gene Expression in Insects
- Force Microscopy Techniques and Applications
- Ubiquitin and proteasome pathways
- Congenital heart defects research
- RNA modifications and cancer
- Neurological disorders and treatments
- Epilepsy research and treatment
- Retinal Development and Disorders
- Genomic variations and chromosomal abnormalities
- Insect Resistance and Genetics
- Cardiac electrophysiology and arrhythmias
- Signaling Pathways in Disease
University of Amsterdam
2017-2025
Amsterdam University Medical Centers
2020-2025
Amsterdam Neuroscience
2011-2024
ERN GUARD-Heart
2024
University Medical Center
2023
Amsterdam UMC Location Vrije Universiteit Amsterdam
2012-2021
Vrije Universiteit Amsterdam
2004-2020
Leiden University
2017
University Medical Center Groningen
2017
University of Groningen
2017
“Spontaneous” Release Trigger Synaptic vesicle release occurs in different phases that can be tightly coupled to action potentials (synchronous), immediately following (asynchronous), or as stochastic events not triggered by (spontaneous). The protein synaptotagmin is thought act the Ca 2+ sensor synchronous phase, but for other two phases, sensors have been identified. Groffen et al. (p. 1614 , published online 11 February) now show cytoplasmic proteins known Doc2 (double C2 domain) are...
Abstract Recent advances in live Ca 2+ imaging with increasing spatial and temporal resolution offer unprecedented opportunities, but also generate an unmet need for data processing. Here we developed SICT, a MATLAB program that automatically identifies rapid rises time-lapse movies low signal-to-noise ratios, using fluorescent indicators. A graphical user interface allows visual inspection of detected events, reducing manual labour to less than 10% while maintaining quality control. The...
Agrin is a heparan sulfate proteoglycan (HSPG) that highly concentrated in the synaptic basal lamina at neuromuscular junction (NMJ). Agrin-like immunoreactiv-ity also detected outside NMJ. Here we show agrin major HSPG component of human glomerular basement membrane (GBM). This addition to perlecan, previously characterized membranes. Antibodies against and an unidentified GBM produced strong staining NMJ, different from observed with anti-perlecan antibodies. In addition, anti-agrin...
Elevation of the intracellular calcium concentration ([Ca2+]i) to levels below 1 microm alters synaptic transmission and induces short-term plasticity. To identify sensors involved in this signalling, we investigated soluble C2 domain-containing proteins found that both DOC2A DOC2B are modulated by submicromolar levels. Fluorescent-tagged translocated plasma membranes after [Ca2+]i elevation. translocation preceded cells co-expressing isoforms. Half-maximal occurred at 450 175 nm[Ca2+]i for...
We determined the specificity of two hamster monoclonal antibodies and a sheep polyclonal antiserum against heparan sulfate proteoglycan isolated from rat glomerular basement membrane. The were characterized by enzyme-linked immunosorbent assay on various membrane components immunoprecipitation with or without heparitinase pre-treatment. These experiments showed that specifically recognize approximately 150-, 105-, 70-kDa core proteins proteoglycan. Recently, we agrin is major in (Groffen,...
Agrin is a heparan sulfate proteoglycan involved in the development of neuromuscular junction during embryogenesis. In addition to this well-characterized function, agrin may have additional functions other tissues and stages development. study we present cDNA sequence human agrin, demonstrate high content adult basement membranes. The N-terminal domain highly similar that chick suggesting function laminin binding. presence three SGXG sequences supports serine-linked glycosylation core...
Paroxysmal dyskinesia (PxD) is a group of movement disorders characterized by recurrent episodes involuntary movements. Familial paroxysmal kinesigenic (PKD) caused PRRT2 mutations, but distinct etiology has been suggested for sporadic PKD. Here we describe cohort patients collected from our outpatient clinic in the period 1996-2011. Fifteen with PxD and 23 subjects three pedigrees familial PKD were screened mutations candidate genes. co-segregated two families occurred cases No detected...
Calcium-dependent exocytosis is regulated by a vast number of proteins. DOC2B synaptic protein that translocates to the plasma membrane (PM) after small elevations in intracellular calcium concentration. The aim this study was investigate role calcium-triggered exocytosis. Using biochemical and biophysical measurements, we demonstrate C2A domain interacts directly with PM calcium-dependent manner. combination electrophysiological, morphological, total internal reflection fluorescent found...
Exocytosis of intracellular vesicles, such as insulin granules, is carried out by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) and Sec1/Munc18 (SM) proteins. An additional regulatory protein, Doc2b (double C2 domain), has recently been implicated in exocytosis from clonal β-cells 3T3-L1 adipocytes. Here, we investigated the role secretion, sensitivity, maintenance whole-body glucose homeostasis. heterozygous (Doc2b(+/-)) homozygous (Doc2b(-/-)) knockout mice...
Kinesin superfamily proteins (KIFs) are molecular motors that transport cellular cargo along the microtubule cytoskeleton. KIF21B is a neuronal kinesin highly enriched in dendrites. The regulation and specificity of involves binding to individual adapters accessory proteins. Moreover, posttranslational modifications either motor protein, their cargos or tubulin regulate motility, recognition unloading cargos. Here we show ubiquitin E3 ligase TRIM3, also known as BERP, interacts with via its...
Abstract Ca 2+ -sensor proteins control the secretion of many neuroendocrine substances. Calcium-secretion coupling may involve several mechanisms. First, -dependent association their tandem C2 domains with phosphatidylserine induce membrane curvature and thereby enhance fusion. Second, SNARE complexes inhibit fusion in absence a trigger. Here we present method using two optically trapped beads coated SNARE-free synthetic membranes to elucidate direct role C2AB domain soluble Doc2b....
Tomosyn was previously identified as a syntaxin-binding protein that inhibits soluble NSF (n-ethylmaleimide-sensitive fusion protein) attachment receptor (SNARE)-mediated secretion. We set out to investigate the distribution of tomosyn mRNA in mammalian brain and found evidence for presence two paralogous genes designated tomosyn-1 -2. In collection tomosyn-2 cDNA clones, we observed four splice variants (named xb-, b-, m- s-tomosyn-2) derived from skipping exons 19 21. This feature is...
Doc2B is a cytosolic protein with binding sites for Munc13 and Tctex-1 (dynein light chain), two C2-domains that bind to phospholipids, Ca2+ SNAREs. Whether functions as calcium sensor akin synaptotagmins, or in other calcium-independent calcium-dependent capacities debated. We here show by mutation overexpression plays distinct roles sequential priming steps mouse adrenal chromaffin cells. Mutating Ca2+-coordinating aspartates the C2A-domain localizes permanently at plasma membrane, renders...
Ca2+-dependent fusion of transport vesicles at their target can be enhanced by intracellular Ca2+ and diacylglycerol. Diacylglycerol induces translocation the vesicle priming factor Munc13 association secretory protein DOC2B to membrane. Here we demonstrate that a rise in is sufficient for Munc13-independent recruitment This novel mechanism occurred readily absence was not influenced mutations abolish binding. Purified (expressed as bacterial protein) bound phospholipids way, suggesting...
<h3>Objective:</h3> To identify the causative gene in a large Dutch family with familial cortical myoclonic tremor and epilepsy (FCMTE). <h3>Methods:</h3> We performed exome sequencing for 3 patients of our FCMTE family. Next, we knock-down (shRNA) rescue experiments by overexpressing wild-type mutant human δ-catenin (CTNND2) proteins mouse neurons compared results morphologic abnormalities postmortem brain. <h3>Results:</h3> identified missense mutation, p.Glu1044Lys, <i>CTNND2</i> that...
A decrease in glomerular heparan sulfate (HS) proteoglycan (PG), without apparent HSPG core protein expression, has been reported to occur diabetic nephropathy (DN). In most studies however, agrin, the major basement membrane, not studied. This prompted us study expression of agrin parallel HS-glycosaminoglycans (GAG) biopsies patients with DN. Furthermore, influence glucose on production cultured podocytes and fetal kidneys was investigated.Cryostat sections renal from DN (n = 8) healthy...