Biology subjects

Asensio, C. S.

Publications and source records attributed to Asensio, C. S..

6 recordsLinked to original sources

bioRxiv2024

Proteomic analysis of the Aggregation Factor from the sponge Clathria (Microciona) prolifera suggests an ancient protein domain toolkit for allorecognition in animals

The discovery that sponges (Porifera) can fully regenerate from aggregates of dissociated cells launched them as one of the earliest experimental models for cell adhesion and allorecognition studies in animals. This process depends on an extracellular glycoprotein complex called the Aggregation Factor (AF). However, our understanding of how animal adhesion and allorecognition mechanisms first evolved is complicated by the fact that the known components of the AF are thought to be unique to sponges. We used label-free quantitative proteomics to identify additional AF components and interacting proteins in the classical model Clathria prolifera and compare them to proteins involved in cell interactions in Bilateria. Our results confirm MAFp3/p4 as the primary components of the AF, but implicate related proteins with calx-beta and wreath domains as additional components. Using AlphaFold, we unveiled close structural similarities of AF components to distant homologs in other animals, previously masked by the stark decay of sequence similarity. The wreath domain, believed to be unique to the AF, was predicted to contain a central beta-sandwich of the same organization as the vWFD domain in extracellular, gel-forming gly-coproteins in other animals. Additionally, we co-purified candidate AF-interacting proteins that share a conserved C-terminus, containing divergent Ig-like and Fn3 domains, a combination also known from IgCAMs. One of these, MAFAP1, may function to link the AF to the surface of cells. Our results highlight the existence of an ancient toolkit of conserved protein domains regulating cell-cell and cell-ECM interactions in all animals, and likely reflect a common origin of cell-adhesion and allorecognition.

biochemistry↗

bioRxiv2020

Pancreatic beta-cell specific deletion of VPS41 causes diabetes due to defects in insulin secretion

Insulin secretory granules (SGs) mediate the regulated secretion of insulin, which is essential for glucose homeostasis. The basic machinery responsible for this regulated exocytosis consists of specific proteins present both at the plasma membrane and on insulin SGs. The protein composition of insulin SGs thus dictates their release properties, yet the mechanisms controlling insulin SG formation, which determines this molecular composition, remain poorly understood. VPS41, a component of the endo-lysosomal tethering HOPS complex, was recently identified as a cytosolic factor involved in the formation of neuroendocrine and neuronal granules. We now find that VPS41 is required for insulin SG biogenesis and regulated insulin secretion. Loss of VPS41 in pancreatic {beta}-cells leads to a reduction in insulin SG number, changes in their transmembrane protein composition, and defects in granule regulated exocytosis. Exploring a human point mutation, identified in patients with neurological but no endocrine defects, we show that the effect on SG formation is independent of HOPS complex formation. Finally, we report that mice with a deletion of VPS41 specifically in {beta}-cells develop diabetes due to severe depletion of insulin SG content and a defect in insulin secretion. In sum, our data demonstrate that VPS41 contributes to glucose homeostasis and metabolism.

physiology↗

bioRxiv2019

VPS41 recessive mutation causes ataxia and dystonia with retinal dystrophy and mental retardation by inhibiting HOPS function and mTORC1 signaling

The vacuolar protein sorting protein 41 (VPS41) is a neuroprotective protein in models of Parkinsons disease (PD). As part of the HOPS (Homotypic fusion and Protein Sorting) complex, VPS41 regulates fusion of lysosomes with late endosomes and autophagosomes. Independent of HOPS, VPS41 regulates transport of newly synthesized lysosomal membrane proteins and secretory proteins. Here we report two brothers with compound heterozygous mutations in VPS41 (VPS41R662* and VPS41S285P), born to healthy and non-consanguineous parents. Both patients displayed transient retinal dystrophy, ataxia and dystonia, with brain MRI findings of cerebellar atrophy and a thin saber-shape corpus callosum. Patient-derived fibroblasts contained enzymatically active lysosomes that were poorly reached by endocytic cargo and failed to attract the mTORC1 complex. Consequently, transcription factor TFE3, a driver of autophagy and lysosomal genes, showed continuous nuclear localization which resulted in elevated LC3-II levels and an impaired response to nutrient starvation. CRISPR/CAS VPS41 HeLa knockout cells showed a similar phenotype that could be rescued by wildtype VPS41 but not by VPS41S285P or VPS41R662*. mTORC1 inhibition was also seen after knockout of HOPS subunits VPS11 or VPS18. Regulated neuropeptide secretion in PC12 VPS41 knockout cells was rescued by VPS41S285P expression, indicating that this HOPS-independent function was preserved. Co-expression of the VPS41S285P and VPS41R662* variants in a C. elegans model of PD abolished the protective effect of VPS41 against -synuclein-induced neurodegeneration. We conclude that both disease-associated VPS41 variants specifically abrogate HOPS function, which leads to a delay in endocytic cargo delivery to lysosomes, mTORC1 inhibition and irresponsiveness to autophagic clues. Our studies signify a link between HOPS function and mTORC1 signaling and imply that HOPS function is required for the neuroprotective effect of VPS41 in PD.

cell biology↗

bioRxiv2019

Differential sorting behavior for soluble and transmembrane cargoes at the trans-Golgi network in endocrine cells.

Regulated secretion of neuropeptides and peptide hormones by secretory granules (SGs) is central to physiology. Formation of SGs occurs at the trans-Golgi network (TGN) where their soluble cargo aggregates to form a dense core, but the mechanisms controlling the sorting of regulated secretory cargoes (soluble and transmembrane) away from constitutively secreted proteins remain unclear. Optimizing the use of the retention using selective hooks (RUSH) method in (neuro-)endocrine cells, we now quantify TGN budding kinetics of constitutive and regulated secretory cargoes. We further show that, by monitoring two cargoes simultaneously, it becomes possible to visualize sorting to the constitutive and regulated secretory pathways in real-time. Further analysis of the localization of SG cargoes immediately after budding from the TGN revealed that, surprisingly, the bulk of two studied transmembrane SG cargoes (phogrin and VMAT2) does not sort directly onto SGs during budding, but rather exit the TGN into non-regulated vesicles to get incorporated to SGs at a later step. This differential behavior of soluble and transmembrane cargoes suggests a more complex model of SG biogenesis than anticipated.

cell biology↗

bioRxiv2019

CCDC186 recruits EARP and controls dense-core vesicle cargo sorting by exit

The regulated release of peptide hormones depends on their packaging into dense-core vesicles (DCVs). Two models have been proposed for DCV cargo sorting. The \"sorting by entry\" model proposes that DCV cargos selectively enter nascent DCVs at the trans-Golgi network (TGN). The \"sorting by exit\" model proposes that sorting occurs by the post-TGN removal of non-DCV cargos and retention of mature DCV cargos. Here we show that the coiled-coil protein CCDC186 controls sorting by exit. Ccdc186 KO insulinoma cells secrete less insulin, fail to retain insulin and carboxypeptidase E in mature DCVs at the cell periphery, and fail to remove carboxypeptidase D from immature DCVs. A mutation affecting the endosome-associated recycling protein (EARP) complex causes similar defects in DCV cargo retention and removal. CCDC186 and EARP may act together to control the post-Golgi retention of cargos in mature DCVs.

cell biology↗

bioRxiv2017

HID-1 controls cargo sorting and dense core formation by influencing trans- Golgi network acidification in neuroendocrine cells

Large dense core vesicles (LDCVs) mediate the regulated release of neuropeptides and peptide hormones. They form at the trans-Golgi network (TGN) where their soluble content aggregates to form a dense core, but the mechanisms controlling biogenesis are still not completely understood. Recent studies have implicated the peripheral membrane protein HID-1 in neuropeptide sorting and insulin secretion. Using CRISPR/Cas9, we generated HID-1 KO rat neuroendocrine cells, and show that the absence of HID-1 results in specific defects in peptide hormone and monoamine storage and regulated secretion. Loss of HID-1 causes a reduction in the number of LDCVs and affects their morphology and biochemical properties due to impaired cargo sorting and dense core formation. HID-1 KO cells also exhibit defects in TGN acidification together with mislocalization of the Golgi-enriched vacuolar H+-ATPase subunit isoform a2. We propose that HID-1 influences early steps in LDCV formation by controlling dense core formation at the TGN.

cell biology↗