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Sigma-1 Receptor Chaperone Function
Research Guide

What is Sigma-1 Receptor Chaperone Function?

Sigma-1 receptor chaperone function refers to the Sigma-1 receptor's role as an endoplasmic reticulum chaperone at the MAM interface regulating protein folding, Ca2+ signaling, and cellular survival.

Sigma-1 receptor (Sig1R) localizes to mitochondria-associated ER membranes (MAM) to modulate inter-organelle Ca2+ transfer and stress responses (Hayashi and Su, 2007, 1738 citations). Ligand binding induces conformational changes that enhance chaperone activity and protein quality control (Su et al., 2010, 456 citations). Over 10 key papers since 2007 document its roles in neurodegeneration and neuroprotection.

Curated Papers

Key Challenges

Why It Matters

Sigma-1 receptor chaperone dysfunction disrupts MAM integrity, contributing to ALS via SIGMAR1 mutations that cause MAM collapse (Watanabe et al., 2016, 220 citations). Pharmacological agonists like fluvoxamine restore MAM function, preventing clinical deterioration in COVID-19 and offering neurorestorative effects in parkinsonism models (Sukhatme et al., 2021, 189 citations; Francardo et al., 2014, 195 citations). These mechanisms link protein misfolding to diseases like ALS and Parkinson's, enabling chaperone-targeted therapies.

Key Research Challenges

Ligand-induced Conformational Dynamics

Resolving precise conformational changes in Sig1R upon ligand binding remains challenging due to its small size and membrane localization. Hayashi and Su (2007) showed Ca2+ regulation but lacked atomic structures. Recent studies call for cryo-EM to map chaperone states (Ryskamp et al., 2019).

MAM Structural Integrity in Disease

SIGMAR1 mutations collapse MAM in ALS models, but quantifying tether protein interactions is difficult (Watanabe et al., 2016). Distinguishing primary from secondary MAM defects requires advanced imaging. Su et al. (2010) highlighted signaling but not quantitative dynamics.

Therapeutic Translation Barriers

Agonists like fluvoxamine show promise in parkinsonism but face blood-brain barrier and selectivity issues (Francardo et al., 2014). Clinical trials need biomarkers for chaperone activity. Hayashi et al. (2009) noted MAM roles but underexplored pharmacokinetics.

Essential Papers

Sigma-1 Receptor Chaperones at the ER- Mitochondrion Interface Regulate Ca2+ Signaling and Cell Survival

Teruo Hayashi, Tsung‐Ping Su · 2007 · Cell · 1.7K citations

MAM: more than just a housekeeper

Teruo Hayashi, Rosario Rizzuto, György Hajnóczky et al. · 2009 · Trends in Cell Biology · 759 citations

The sigma-1 receptor chaperone as an inter-organelle signaling modulator

Tsung‐Ping Su, Teruo Hayashi, Tangui Maurice et al. · 2010 · Trends in Pharmacological Sciences · 456 citations

Sigma-1 Receptor Chaperone at the ER-Mitochondrion Interface Mediates the Mitochondrion-ER-Nucleus Signaling for Cellular Survival

Tomohisa Mori, Teruo Hayashi, Eri Hayashi et al. · 2013 · PLoS ONE · 292 citations

The membrane of the endoplasmic reticulum (ER) of a cell forms contacts directly with mitochondria whereby the contact is referred to as the mitochondrion-associated ER membrane or the MAM. Here we...

The sigma-1 receptor: roles in neuronal plasticity and disease

Saı̈d Kourrich, Tsung‐Ping Su, Michiko Fujimoto et al. · 2012 · Trends in Neurosciences · 235 citations

Mitochondria‐associated membrane collapse is a common pathomechanism in <i> <scp>SIGMAR</scp> 1 </i> ‐ and <i> <scp>SOD</scp> 1 </i> ‐linked <scp>ALS</scp>

Seiji Watanabe, Hristelina Ilieva, Hiromi Tamada et al. · 2016 · EMBO Molecular Medicine · 220 citations

Abstract A homozygous mutation in the gene for sigma 1 receptor (Sig1R) is a cause of inherited juvenile amyotrophic lateral sclerosis ( ALS 16). Sig1R localizes to the mitochondria‐associated memb...

Neuronal Sigma-1 Receptors: Signaling Functions and Protective Roles in Neurodegenerative Diseases

Daniel A. Ryskamp, Svetlana A. Korban, Vladimir Zhemkov et al. · 2019 · Frontiers in Neuroscience · 195 citations

Sigma-1 receptor (S1R) is a multi-functional, ligand-operated protein situated in endoplasmic reticulum (ER) membranes and changes in its function and/or expression have been associated with variou...

Reading Guide

Foundational Papers

Start with Hayashi and Su (2007, 1738 citations) for core MAM chaperone and Ca2+ mechanisms, then Su et al. (2010, 456 citations) for signaling overview, followed by Mori et al. (2013) for nucleus signaling pathway.

Recent Advances

Study Watanabe et al. (2016, 220 citations) for ALS MAM collapse, Ryskamp et al. (2019, 195 citations) for neurodegeneration roles, and Sukhatme et al. (2021, 189 citations) for fluvoxamine therapeutics.

Core Methods

Core techniques include MAM fractionation for Sig1R localization (Hayashi et al., 2009), IP-Western for IP3R interactions (Hayashi and Su, 2007), live-cell Ca2+ imaging (Mori et al., 2013), and CRISPR knockouts for disease models (Watanabe et al., 2016).

How PapersFlow Helps You Research Sigma-1 Receptor Chaperone Function

Discover & Search

Research Agent uses citationGraph on Hayashi and Su (2007, 1738 citations) to map 50+ MAM chaperone papers, then exaSearch for 'Sigma-1 MAM ALS mutations' to uncover Watanabe et al. (2016). findSimilarPapers expands to 2021 fluvoxamine studies.

Analyze & Verify

Analysis Agent applies readPaperContent to extract Ca2+ flux data from Mori et al. (2013), then runPythonAnalysis with NumPy to quantify survival signaling curves. verifyResponse (CoVe) and GRADE grading confirm MAM collapse claims in Watanabe et al. (2016) against 10 citing papers.

Synthesize & Write

Synthesis Agent detects gaps in ALS MAM therapeutics post-Watanabe (2016), flags contradictions between Su et al. (2010) signaling and Ryskamp (2019) neurodegeneration. Writing Agent uses latexEditText for MAM diagrams, latexSyncCitations for 20-paper review, and latexCompile for submission-ready manuscript.

Use Cases

"Extract Ca2+ signaling data from Sigma-1 MAM papers and plot dose-response curves"

Research Agent → searchPapers('Sigma-1 Ca2+ MAM') → Analysis Agent → readPaperContent(Hayashi 2007) → runPythonAnalysis(NumPy matplotlib curve fitting) → researcher gets publication-quality survival plots with p-values.

"Write LaTeX review on Sig1R chaperone in ALS with citations and MAM figure"

Synthesis Agent → gap detection(Watanabe 2016) → Writing Agent → latexEditText(structured review) → latexSyncCitations(15 papers) → latexGenerateFigure(MAM schematic) → latexCompile → researcher gets PDF with synced refs and vector diagram.

"Find GitHub repos analyzing SIGMAR1 mutations from Watanabe ALS paper"

Research Agent → paperExtractUrls(Watanabe 2016) → paperFindGithubRepo(SIGMAR1 ALS) → githubRepoInspect(code notebooks) → researcher gets 3 repos with MAM simulation scripts and mutation datasets.

Automated Workflows

Deep Research workflow scans 50+ Sig1R papers via citationGraph from Hayashi (2007), generating structured MAM chaperone report with GRADE scores. DeepScan applies 7-step CoVe to verify Watanabe (2016) ALS claims against 220 citations. Theorizer synthesizes ligand-chaperone theory from Su (2010) and Ryskamp (2019).

Try Doxa for Sigma-1 Receptor Chaperone Function Research

Frequently Asked Questions

What defines Sigma-1 receptor chaperone function?

Sigma-1 receptor acts as an ER chaperone at MAM regulating protein folding, Ca2+ signaling, and survival (Hayashi and Su, 2007).

What methods study Sig1R MAM function?

Confocal imaging tracks MAM contacts, ligand binding assays measure chaperone activation, and knockout models assess survival (Mori et al., 2013; Watanabe et al., 2016).

What are key papers on Sig1R chaperone?

Hayashi and Su (2007, 1738 citations) established MAM Ca2+ roles; Su et al. (2010, 456 citations) detailed inter-organelle signaling.

What open problems exist in Sig1R research?

Atomic structures of ligand-bound states, quantitative MAM tether dynamics in ALS, and selective agonist pharmacokinetics remain unsolved (Ryskamp et al., 2019).