Biology subjects

De Pace, R.

Publications and source records attributed to De Pace, R..

5 recordsLinked to original sources

bioRxiv2025

Spatial Regulation of Lysosomal Vesicle Acidification Along the Axon via mRAVE-Dependent v-ATPase Assembly

Lysosomal acidification is essential for neuronal homeostasis, supporting degradative clearance and metabolic signaling in all neuronal domains. Yet, how lysosomal acidification is spatially regulated within neurons remains unclear. Here, we show that assembly of the membrane-embedded V0 and cytosolic V1 domains of the vacuolar H-ATPase (v-ATPase) -- the proton pump that drives lysosomal acidification -- governs spatial and functional lysosome diversity. In non-neuronal cells, V1-V0 association is higher in perinuclear lysosomes, correlating with increased acidity of this population. In neurons, axonal V0-positive vesicles move bidirectionally, whereas V1-V0 -positive vesicles move almost exclusively in the retrograde direction, consistent with the higher acidity of retrograde lysosomal vesicles. Depletion of DMXL2, a subunit of the mRAVE complex that promotes V1-V0 assembly, reduces V1 association, acidification, transport, and proteolytic activity of retrograde lysosomal vesicles in the axon. Together, these findings reveal a spatially regulated mechanism for the acidification of axonal lysosomal vesicles and identify mRAVE-dependent v-ATPase assembly as a key determinant of this process. Subjects: Organelles, Trafficking, Disease

cell biology↗

bioRxiv2024

Programmed ribosomal frameshifting during PLEKHM2 mRNA decoding generates a constitutively active mediator of kinesin-1-dependent lysosome transport

Programmed ribosomal frameshifting is a process where a proportion of ribosomes change their reading frame on an mRNA1, rephasing the ribosome relative to the mRNA. While frameshifting is commonly employed by viruses2, very few phylogenetically conserved examples are known in nuclear encoded genes and some of the evidence is controversial3,4. Here we report a +1 frameshifting event during decoding of the human gene PLEKHM25. This frameshifting occurs at the sequence UCC_UUU_CGG, which is conserved in vertebrates and is similar to an influenza virus sequence that frameshifts with similar efficiency6,7. The new C-terminal domain generated by this frameshift forms an -helix, which relieves PLEKHM2 from autoinhibition and allows it to move to the tips of cells via association with kinesin-1 without requiring activation by ARL8. Reintroducing both the canonically-translated and frameshifted protein are necessary to restore normal contractile function of PLEKHM2-knockout cardiomyocytes, demonstrating the necessity of frameshifting for normal cardiac activity.

molecular biology↗

bioRxiv2023

The Reelin Receptor ApoER2 is a Cargo for the Adaptor Protein Complex AP-4: Implications for Hereditary Spastic Paraplegia.

Adaptor protein complex 4 (AP-4) is a heterotetrameric complex that promotes protein export from the trans-Golgi network. Mutations in each of the AP-4 subunits cause a complicated form of Hereditary Spastic Paraplegia (HSP). Herein, we report that ApoER2, a receptor in the Reelin signaling pathway, is a cargo of the AP-4 complex. We identify the motif ISSF/Y within the ApoER2 cytosolic domain as necessary for interaction with the canonical signal-binding pocket of the {micro}4 (AP4M1) subunit of AP-4. AP4E1-knock-out (KO) HeLa cells and hippocampal neurons from Ap4e1-KO mice display increased Golgi localization of ApoER2. Furthermore, hippocampal neurons from Ap4e1-KO mice and AP4M1-KO human iPSC-derived cortical i3Neurons exhibit reduced ApoER2 protein expression. Analyses of biosynthetic transport of ApoER2 reveal differential post-Golgi trafficking of the receptor, with lower axonal distribution in KO compared to wild-type neurons, indicating a role of AP-4 and the ISSF/Y motif in the axonal localization of ApoER2. Finally, analyses of Reelin signaling in mouse hippocampal and human cortical KO neurons show that AP4 deficiency causes no changes in Reelin-dependent activation of the AKT pathway and only mild changes in Reelin-induced dendritic arborization, but reduces Reelin-induced ERK phosphorylation, CREB activation, and Golgi deployment. Altogether, this work establishes ApoER2 as a novel cargo of the AP-4 complex, suggesting that defects in the trafficking of this receptor and in the Reelin signaling pathway could contribute to the pathogenesis of HSP caused by mutations in AP-4 subunits.

cell biology↗

bioRxiv2023

Single-cell multiomic analysis reveals the involvement of Type I interferon-responsive CD8+ T cells in amyloid beta-associated memory loss

Alzheimers disease (AD) is the leading cause of dementia worldwide, but there are limited therapeutic options and no current cure. While the involvement of microglia in AD has been highly appreciated, the role of other innate and adaptive immune cells remains largely unknown, partly due to their scarcity and heterogeneity. This study aimed to study non-microglial immune cells in wild type and AD-transgenic mouse brains across different ages. Our results uncovered the presence of a unique CD8+ T cell population that were selectively increased in aging AD mouse brains, here referred to as "disease-associated T cells (DATs)". These DATs were found to express an elevated tissue-resident memory and Type I interferon-responsive gene signature. Further analysis of aged AD mouse brains showed that these CD8+ T cells were not present in peripheral or meningeal tissues. Preventing CD8+ T cell development in AD-transgenic mice via genetic deletion of beta-2 microglobulin (B2m) led to a reduction of amyloid-{beta} plaque formation in aged mice, and improved memory in AD-transgenic mice as early as four months of age. The integration of transcriptomic and epigenomic profiles at the single-cell level revealed potential transcription factors that reshape the regulomes of CD8+ T cells. These findings highlight a critical role for DATs in the progression of AD and provide a new avenue for treatment.

immunology↗

bioRxiv2020

Neuronal Enhancers are Hotspots For DNA Single-Strand Break Repair

Genome stability is essential for all cell types. However, defects in DNA repair frequently lead to neurodevelopmental and neurodegenerative diseases, underscoring the particular importance of DNA repair in long-lived post-mitotic neurons. The neuronal genome is subjected to a constant barrage of endogenous DNA damage due to high levels of oxidative metabolism in the central nervous system. Surprisingly, we know little about the identity of the lesion(s) that accumulate in neurons and whether they accrue throughout the genome or at specific loci. Here, we show that neurons, but not other post-mitotic cells, accumulate unexpectedly high numbers of DNA single-strand breaks (SSBs) at specific sites within the genome. These recurrent SSBs are found within enhancers, and trigger DNA repair through recruitment and activation of poly(ADP-ribose) polymerase-1 (PARP1) and XRCC1, the central SSB repair scaffold protein. Notably, deficiencies in PARP1, XRCC1, or DNA polymerase {beta} elevate the localized incorporation of nucleotides, suggesting that the ongoing DNA synthesis at neuronal enhancers involves both short-patch and long-patch SSB repair processes. These data reveal unexpected levels of localized and continuous DNA single-strand breakage in neurons, suggesting an explanation for the neurodegenerative phenotypes that occur in patients with defective SSB repair.

neuroscience↗