bioRxiv Science⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.01.08.574743

Interactors of sacsin DNAJ domain identify function in organellar transport and membrane composition relevant to ARSACS pathogenesis

Pare, A. M.·Cheng-Boivin, Z.·Dabbaghizadeh, A.·Minotti, S.·Durham, H. D.·Gentil, B. J.
View original source ↗Export metadata ↓

Abstract

Autosomal Recessive Spastic Ataxia of the Charlevoix Saguenay (ARSACS) is caused by loss of function mutations in the SACS gene encoding sacsin, a 520kDa protein with multiple functional domains. The goal of this study was to identify client proteins interacting with the J domain, a cochaperone domain interacting with Hsp70 chaperones, to gain insights into sacsins function and its disruption in experimental models of ARSACS. Pull downs from mouse brain identified Rabs and Rab-associated proteins including Rab1b, ARF5 and endophilin B2, involved in organelle trafficking. In cell and mouse models of ARSACS, higher molecular weight species of Rab1b were identified on SDS-PAGE in addition to the normal 25kDa band and Rab1was retained in the soma along with membranous organelles (i.e., ER, Golgi and ATG9 autophagic vesicles). These changes were reversed by expression of the DNAJ domain or the Ubl domain of sacsin and occurred independent of the formation of abnormal bundles of intermediate filaments, a key feature of ARSACS. Although Rab1b was associated with both Golgi and ER in both Sacs+/+ and Sacs-/- cells, expression of the DNAJ domain or the Ubl domain of sacsin increased Rab1b association with ER and restored normal electrophoretic mobility. Finally, subcellular distribution of another membrane protein, neuroplastin, a key receptor for synapse formation and plasticity, also was impaired, pointing to a general problem in Rab-dependent membrane trafficking in the absence of sacsin.

Explore related subjects

cell biologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Pare, A. M., Cheng-Boivin, Z., Dabbaghizadeh, A., Minotti, S., Durham, H. D., Gentil, B. J.. 2024-01-09. Interactors of sacsin DNAJ domain identify function in organellar transport and membrane composition relevant to ARSACS pathogenesis. https://doi.org/10.1101/2024.01.08.574743

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

RCDome: A Multi-Database Human Gene Atlas of Regulated Cell Death

Introduction: Regulated cell death (RCD) governs tissue homeostasis, development, and disease, and is executed or regulated by specific genes. Yet for the researcher asking which genes execute or regulate a given RCD form, the answer is rarely simple: gene lists for the same form rarely agree across databases, many associations carry no traceable source, and most have never been systematically checked against primary literature. We built RCDome to answer the most basic question a researcher can ask: where did this gene-RCD association come from, and what is the evidence? Methods: RCDome is a multi-database human gene atlas built through a staged architecture integrating multi-source compilation, literature validation and evidence recovery, mechanistic classification, human-governed ontological adjudication, and web deployment. Five complementary evidence channels (PubMed Boolean search, curated databases, AI-assisted screening, manual curation, and Elicit systematic review) were integrated from 20 public databases into a unified matrix. Sixty-two original name strings were canonicalized into 53 RCD-related entities with curator-adjudicated operational definitions and ontological levels. Gene-RCD associations were systematically evaluated through an independent DeepSeek two-call LLM validation, Europe PMC full-text recovery and deep evidence extraction, an independent Consensus literature-search channel, and GPT-4o arbitration of disagreements. Source-grounding controls rejected extracted evidence not found verbatim in the source document, while the governance contract was enforced as executable code. Results: The compendium holds 22,473 association rows spanning 9,265 unique HGNC-validated genes (21,568 unique gene-RCD pairs). Evidence-first adjudication resolved 5,138 pairs (23.8%) as mechanistically involved; across the 4,775 role-resolved pairs, 225 (4.7%) are executors, 4,455 (93.3%) are regulators, and 95 are markers, revealing a small death-executing core embedded in a vast regulatory network. Under a separate seven-class mechanistic criterion applied to all 22,473 rows, only 3,063 (13.6%) were mechanistically confirmed and 286 (1.3%) were database-only with no verifiable paper trail. Conclusion: RCDome makes the RCD evidence landscape measurable and traceable, showing that AI-assisted curation can be verifiable, human-governed, and explicit about uncertainty. It is delivered as a Shiny web application that lets any researcher query the atlas and inspect the evidence behind each association. Availability: RCDome is freely available at https://rcdome.org/ (source code and data at https://github.com/BioCancerInformatics/RCDome).

cell biology↗
bioRxiv2026

Circadian Clock Coordination of the Notch-to-Wnt Signaling Switch Promotes Regenerative Myogenesis

Regenerative deficits of muscle stem cells (MuSCs) contribute to progressive muscle loss in muscular dystrophy. Successful regenerative repair requires a Notch to Wnt switch to allow MuSC expansion and myogenic differentiation, yet the underlying mechanisms remain poorly understood. Leveraging complementary genetic and pharmacological approaches, here we identify the circadian clock as a key regulator of the Notch to Wnt signaling transition to promote regeneration with therapeutic potential for dystrophic disease. Circadian clock activity marks cycling myogenic progenitors during muscle regeneration, and clock induction occurs in concert with Notch activation. We identify that key components of the Notch pathway are direct transcriptional targets of the clock that were induced by clock activation. Mechanistically, clock coordination of Notch and Wnt signaling promoted MuSC proliferative expansion while facilitating myogenic progression during regeneration. Importantly, this clock-regulated mechanism was preserved in dystrophin-deficient mouse and human myoblasts, and clock-activating compounds enhanced regenerative myogenesis in dystrophic muscle. Collectively, our findings uncover a circadian clock-controlled mechanism that orchestrates regenerative signaling transition with potential for therapeutic targeting to restore regenerative capacity in dystrophic disease.

cell biology↗
bioRxiv2026

The yeast Gcn2 protein kinase mediates P-body formation both through its activity with eIF2α and with non-canonical substrates

P-bodies (PBs) are control hubs for RNA processing and storage that form when translation initiation is inhibited, including during stress. In yeast, Gcn2 is the sole eIF2 alpha kinase that inhibits translation initiation in response to diverse stresses. We show that PB formation depends strongly on Gcn2 during amino acid starvation but only partially during oxidative stress. Constitutively active Gcn2 also induces PB formation in unstressed cells. Surprisingly, PBs are still constitutively formed in a gcn3 mutant strain that is insensitive to eIF2 alpha phosphorylation suggesting that Gcn2 also promotes PB formation independently of eIF2 alpha phosphorylation. Analysis of several putative Gcn2-substrates involved in RNA metabolism identified several proteins required for Gcn2-mediated PB formation. Among these, Smu2, which was not previously implicated in PB formation, localises to PBs and is required for stress-induced coalescence of mRNA granules into PBs. Together, our findings indicate that Gcn2 promotes PB formation via two complementary routes: eIF2 alpha phosphorylation, which generates untranslated mRNAs, and Smu2-dependent maturation of mRNA granules into PBs.

cell biology↗