An iPSC-derived neuronal model of DNAJC6 parkinsonism reveals neurodevelopmental and synaptic vesicle recycling defects
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ABSTRACT:
PROVIDER: PRJNA859666 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR20280565.fastq.gz | Fastqsanger.gz | |||
| SRR20280566.fastq.gz | Fastqsanger.gz | |||
| SRR20280567.fastq.gz | Fastqsanger.gz | |||
| SRR20280568.fastq.gz | Fastqsanger.gz | |||
| SRR20280569.fastq.gz | Fastqsanger.gz |
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Project description:Biallelic mutations in DNAJC6 cause a complex, early-onset movement disorder characterized by rapidly progressive parkinsonism-dystonia in childhood. The disease is commonly associated with additional neurodevelopmental, neurological and neuropsychiatric features. Currently, there are no disease-specific treatments for this condition, resulting in significant morbidity and risk of premature mortality. To investigate the underlying disease mechanisms in childhood-onset DNAJC6 parkinsonism, we generated induced pluripotent stem cells (iPSC) from three patients harboring pathogenic loss-of-function DNAJC6 mutations and subsequently developed a midbrain dopaminergic (mDA) neuronal model of disease. DNAJC6 encodes auxilin, a co-chaperone protein involved in clathrin-mediated synaptic vesicle (SV) recycling at the presynaptic terminal. When compared to age-matched and CRISPR-corrected isogenic controls, the neuronal cell model revealed disease-specific auxilin deficiency as well as disturbance of synaptic vesicle recycling and homeostasis. We also observed dysregulation of key neurodevelopmental pathways affecting ventral midbrain pattering and neuronal maturation.
2023-12-31 | GSE208353 | GEO
Project description:Synaptojanin is a polyphosphoinositide phosphatase that is found at synapses and binds to proteins implicated in endocytosis. For these reasons, it has been proposed that synaptojanin is involved in the recycling of synaptic vesicles. Here, we demonstrate that the unc-26 gene encodes the Caenorhabditis elegans ortholog of synaptojanin. unc-26 mutants exhibit defects in vesicle trafficking in several tissues, but most defects are found at synaptic termini. Specifically, we observed defects in the budding of synaptic vesicles from the plasma membrane, in the uncoating of vesicles after fission, in the recovery of vesicles from endosomes, and in the tethering of vesicles to the cytoskeleton. Thus, these results confirm studies of the mouse synaptojanin 1 mutants, which exhibit defects in the uncoating of synaptic vesicles (Cremona, O., G. Di Paolo, M.R. Wenk, A. Luthi, W.T. Kim, K. Takei, L. Daniell, Y. Nemoto, S.B. Shears, R.A. Flavell, D.A. McCormick, and P. De Camilli. 1999. Cell. 99:179-188), and further demonstrate that synaptojanin facilitates multiple steps of synaptic vesicle recycling.
| S-EPMC2175188 | biostudies-literature
Project description:The trigger for synaptic vesicle exocytosis is Ca(2+), which enters the synaptic bouton following action potential stimulation. However, spontaneous release of neurotransmitter also occurs in the absence of stimulation in virtually all synaptic boutons. It has long been thought that this represents exocytosis driven by fluctuations in local Ca(2+) levels. The vesicles responding to these fluctuations are thought to be the same ones that release upon stimulation, albeit potentially triggered by different Ca(2+) sensors. This view has been challenged by several recent works, which have suggested that spontaneous release is driven by a separate pool of synaptic vesicles. Numerous articles appeared during the last few years in support of each of these hypotheses, and it has been challenging to bring them into accord. We speculate here on the origins of this controversy, and propose a solution that is related to developmental effects. Constitutive membrane traffic, needed for the biogenesis of vesicles and synapses, is responsible for high levels of spontaneous membrane fusion in young neurons, probably independent of Ca(2+). The vesicles releasing spontaneously in such neurons are not related to other synaptic vesicle pools and may represent constitutively releasing vesicles (CRVs) rather than bona fide synaptic vesicles. In mature neurons, constitutive traffic is much dampened, and the few remaining spontaneous release events probably represent bona fide spontaneously releasing synaptic vesicles (SRSVs) responding to Ca(2+) fluctuations, along with a handful of CRVs that participate in synaptic vesicle turnover.
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Project description:Pyramidal neurons in the cortex are embedded in distinct information processing pathways. Cortical layer 5 (L5) intratelencephalic (IT) and pyramidal tract (PT) neurons receive different input and project to distinct brain regions. The synaptic molecular signatures that define synaptic connectivity and function of L5 IT and PT neurons are largely unknown. Here, we use an optimized proximity biotinylation workflow to characterize the excitatory postsynaptic proteomes of L5 IT and PT neurons in intact somatosensory circuits. We find that differential expression of neurotransmitter receptors, ion channels and cell-surface proteins (CSPs), most prominently of the leucine-rich repeat (LRR) family, specifies L5 IT and PT neuron input connectivity and function. Our analysis further uncovers differential vulnerability to neurodevelopmental disorders for L5 IT and PT neurons, with a marked enrichment of autism risk genes in the postsynaptic excitatory proteome of IT, but not of PT, neurons. Together, cell type- and input type-specific synaptic proteome profiling implies that many of the proteins specifying connectivity and function of two closely related cortical pyramidal cell types also underlie their differential vulnerability to neurodevelopmental disorders.
2024-11-04 | PXD046812 | Pride
Project description:Lipids and their metabolic enzymes are a critical point of regulation for the membrane curvature required to induce membrane fusion during synaptic vesicle recycling. One such enzyme is diacylglycerol kinase theta (DGKq), which produces phosphatidic acid (PtdOH) that generates negative membrane curvature. Synapses lacking DGKq have significantly slower rates of endocytosis, implicating DGKq as an endocytic regulator. Importantly, DGKq kinase activity is required for this function. However, protein regulators of DGKq’s kinase activity in neurons have never been identified. In this study, we employed APEX2 proximity labeling and mass spectrometry to identify endogenous interactors of DGKq in neurons and assayed their ability to modulate its kinase activity. Seven endogenous DGKq interactors were identified and notably, synaptotagmin-1 (Syt1) increased DGKq kinase activity 10-fold. This study is the first to validate endogenous DGKq interactors at the mammalian synapse and suggests a coordinated role between DGKq-produced PtdOH and Syt1 in synaptic vesicle recycling.
2021-12-18 | PXD030495 | Pride
Project description:Synaptic vesicles are storage organelles for neurotransmitters in the pre-synaptic cytosol. When an action potential arrives at the pre-synaptic terminal, they fuse with the pre-synaptic membrane and neurotransmitters are released. In this project, we set out to study the protein interactions formed in synaptic vesicle membranes. For this, we first assessed the proteome of five independent vesicle preparations. Using chemical cross-linking, we then tackled the interactions of the major protein components. To gain further insights, we combined this approach with a chemical labelling strategy. Specific protein interactions were then studied after (i) treating the vesicles with Botulinum neurotoxin B, (ii) binding the soluble SNARE complex, and (iii) fusion of the vesicles with empty liposomes. Our findings reveal stable interaction modules in synaptic vesicles.
2020-12-09 | PXD020859 | Pride
Project description:Synaptic vesicles (SVs) are composed of approximately 10 types of transmembrane proteins that must be recycled after exocytosis of neurotransmitter. The mechanisms for resorting these proteins into synaptic vesicles once incorporated into the plasma membrane after exocytosis are poorly understood. The adaptor complex AP-2 is the major clathrin-associated adaptor for cargo recognition at the plasma membrane. Here, we have investigated its role in synaptic vesicle endocytosis. shRNA-mediated knockdown of the AP-2 complex results in an approximately 96% reduction of this protein complex in primary neurons. We used simultaneous expression of shRNA and pHluorin-tagged vesicle components to show that the absence of AP-2 significantly slows but does not prevent the endocytosis of four of the major synaptic vesicle transmembrane proteins. We show that in the absence of AP-2, the AP-1 adaptor complex appears to functionally substitute for AP-2 but results in complex internalization kinetics that are now sensitive to the guanine-nucleotide exchange factor for ADP-ribosylation factor GTPase (ARF-GEF) inhibitor brefeldin-A (BFA). Simultaneous removal of both AP-2 and AP-1 prevents this compensatory substitution and results in slowed but functional endocytosis. These results demonstrate that in the absence of AP-2, SV proteins still become endocytosed, and synaptic vesicle recycling remains operational.
| S-EPMC2713063 | biostudies-literature
Project description:Synaptic vesicles are recycled locally within presynaptic specializations. We examined how vesicles are reused after endocytosis, using transgenic mice expressing the genetically encoded fluorescent indicator synaptopHluorin in subsets of neurons. At both excitatory and inhibitory synapses in cultured hippocampal neurons, newly endocytosed vesicles did not preferentially enter the releasable pool of vesicles. Rather, they entered the reserve pool first and subsequently the readily releasable pool over a period of several minutes. All vesicles in the recycling pool could be accessed by spaced stimuli, arguing against preferential local reuse of the readily releasable vesicles. Interestingly, nearly half the vesicles at excitatory synapses, and a third at inhibitory synapses, could not be recruited for release even by sustained stimuli. We conclude that, at presynaptic terminals in the hippocampus, most vesicles vacate release sites after exocytosis and are replaced by existing vesicles from the reserve pool, placing constraints on kiss-and-run recycling.
| S-EPMC1087931 | biostudies-literature
Project description:Botulinum toxins are metalloproteases that act inside nerve terminals and block neurotransmitter release through their cleavage of components of the exocytosis machinery. These toxins are used to treat human diseases that are characterized by hyperfunction of cholinergic terminals. Recently, evidence has accumulated that gangliosides and synaptic vesicle proteins cooperate to mediate toxin binding to the presynaptic terminal. The differential distribution of synaptic vesicle protein receptors, gangliosides and toxin substrates in distinct neuronal populations opens up the possibility of using different serotypes of botulinum toxins for the treatment of central nervous system diseases caused by altered activity of selected neuronal populations.
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Project description:Efficient endocytosis is crucial for maintaining synaptic transmission because of its role in retrieving constituent membrane and associated proteins. In the past three decades three modes of endocytosis have been proposed involving the central nervous system: clathrin-mediated endocytosis, kiss-and-run endocytosis and bulk endocytosis. These forms of endocytosis can be induced under different conditions, but their detailed molecular mechanisms and functions are largely unknown. Here, we review the existence and initiation of all three modes of endocytosis at a giant glutamatergic synapse, the calyx of Held. The possibility of direct electrophysiology recording in this synapse allows for accurate tracking of exocytosis and endocytosis via capacitance measurements. Future aims will be focused on identifying the molecules that undergo the different mechanisms of endocytosis and the conditions under which different forms of endocytosis predominate.
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