{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T15:10:18Z","timestamp":1788793818563,"version":"build-2803163510"},"posted":{"date-parts":[[2026,3,11]]},"group-title":"Neuroscience","reference-count":66,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T00:00:00Z","timestamp":1773187200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"name":"Pilot Award for scRNAseq from the University of Florida Center for Neurodegenerative Disease Research"},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"crossref","award":["1R21NS136890-01A1"],"award-info":[{"award-number":["1R21NS136890-01A1"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,9,3]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                <jats:p>\n                  Pathogenic variants in\n                  <jats:italic>leucine-rich repeat kinase 2<\/jats:italic>\n                  (\n                  <jats:italic>LRRK2<\/jats:italic>\n                  ),\n                  <jats:italic>RAB32<\/jats:italic>\n                  , and\n                  <jats:italic>vacuolar protein sorting 35<\/jats:italic>\n                  (\n                  <jats:italic>VPS35<\/jats:italic>\n                  ) cause dominantly inherited, late-onset Parkinson\u2019s disease (PD). Mutations in all three genes constitutively activate LRRK2 kinase activity, enhancing innate immune defense against pathogens; however, chronic activation is linked to dopaminergic neuronal degeneration. LRRK2 and RAB32 are highly expressed in all myeloid cells including brain microglia, whereas VPS35, a core component of the retromer, is ubiquitously expressed. Nevertheless, the VPS35 p.D620N substitution induces the greatest constitutive increase in endogenous LRRK2 kinase activity, and its consequences for immune function remain unclear. We therefore examined the transcriptomic and functional effects of wild type (WT) and Vps35 p.D620N knock-in mice (VKI) from microglia, isolated from brains of na\u00efve animals at six-month of age, and initially analyzed by single-cell RNA sequencing (scRNAseq). Despite the absence of overt behavioral differences, differential gene expression revealed genotype-dependent changes in antimicrobial humoral immunity, lysosomal stress sensing, and phagocytosis.\n                  <jats:italic>S100 family genes<\/jats:italic>\n                  and\n                  <jats:italic>lipocalin 2<\/jats:italic>\n                  were markedly upregulated, a finding subsequently validated by gene expression and immunohistochemistry. Downregulation was also observed in pathways governing microglial regulation of synaptic transmission, neuronal development and homeostatic immune signaling. Peripherally-administered lipopolysaccharide (LPS) stimulated microglial activation and phagocytic markers in WT brain, and further increased morphological activation and synaptic engulfment in VKI animals. Compared to WT, Vps35 p.D620N drives a chronic pro-inflammatory microglial state characterized by elevated innate immune signaling, lysosomal stress and enhanced phagocytic activity. Hence, heightened microglial sensitivity, further exacerbated by a peripheral immune challenge, offers a parsimonious, if multicellular, explanation for the multifactorial etiology of PD, and may help to account for its penetrance and variable expressivity. Together, these findings provide mechanistic insight into how retromer dysfunction and LRRK2 kinase hyperactivity intersect with microglial biology to influence PD pathogenesis, potentially promoting synaptic remodeling and neurodegenerative vulnerability.\n                <\/jats:p>","DOI":"10.64898\/2026.03.09.710482","type":"posted-content","created":{"date-parts":[[2026,3,11]],"date-time":"2026-03-11T19:15:22Z","timestamp":1773256522000},"source":"Crossref","is-referenced-by-count":0,"title":["Vps35 p.D620N causes Lrrk2 kinase hyperactivity, chronic microglial activation and inflammation"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8088-3469","authenticated-orcid":false,"given":"Isaac Bul","family":"Deng","sequence":"first","affiliation":[{"name":"Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mengfei","family":"Bu","sequence":"additional","affiliation":[{"name":"Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA"},{"name":"Viral Immunology and Intravital Imaging Section, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, Maryland, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4315-0482","authenticated-orcid":false,"given":"Jordan","family":"Follett","sequence":"additional","affiliation":[{"name":"Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Robert C.","family":"Sharp","sequence":"additional","affiliation":[{"name":"Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5546-7084","authenticated-orcid":false,"given":"Adamantios","family":"Mamais","sequence":"additional","affiliation":[{"name":"Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leyna","family":"Xoi","sequence":"additional","affiliation":[{"name":"Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA"},{"name":"Department of Biostatistics, University of Florida, Gainesville, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fahong","family":"Yu","sequence":"additional","affiliation":[{"name":"Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Georges","family":"Rabil","sequence":"additional","affiliation":[{"name":"Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shannon","family":"Wall","sequence":"additional","affiliation":[{"name":"Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1159-5321","authenticated-orcid":false,"given":"Matthew J.","family":"Farrer","sequence":"additional","affiliation":[{"name":"Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, Florida, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026090707351601000_2026.03.09.710482v2.1","doi-asserted-by":"publisher","DOI":"10.1523\/JNEUROSCI.4029-08.2009"},{"key":"2026090707351601000_2026.03.09.710482v2.2","doi-asserted-by":"publisher","DOI":"10.1038\/nrn.2016.178"},{"key":"2026090707351601000_2026.03.09.710482v2.3","doi-asserted-by":"publisher","DOI":"10.1002\/mds.27115"},{"key":"2026090707351601000_2026.03.09.710482v2.4","doi-asserted-by":"crossref","first-page":"103179","DOI":"10.1016\/j.conb.2026.103179","article-title":"How to discover novel genes that cause Parkinson\u2019s disease","volume":"98","year":"2026","journal-title":"Curr. 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