LRSAM1 Gene

LRSAM1 Gene — Leucine Rich Repeat And Sterile Alpha Motif 1

Overview

Lrsam1 Gene plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Leucine Rich Repeat And Sterile Alpha Motif 1</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>LRSAM1</td></tr>
<tr><td><strong>Full Name</strong></td><td>Leucine Rich Repeat And Sterile Alpha Motif 1</td></tr>
<tr><td><strong>Chromosome</strong></td><td>9q33.3</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[90661](https://www.ncbi.nlm.nih.gov/gene/90661)</td></tr>
<tr><td><strong>OMIM</strong></td><td>610933</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000148450</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q6UWP7](https://www.uniprot.org/uniprot/Q6UWP7)</td></tr>
<tr><td><strong>Protein Class</strong></td><td>E3 ubiquitin ligase</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Charcot-Marie-Tooth Disease, Amyotrophic Lateral Sclerosis</td></tr>
</table>
</div>

Introduction

...

LRSAM1 Gene — Leucine Rich Repeat And Sterile Alpha Motif 1

Overview

Lrsam1 Gene plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Leucine Rich Repeat And Sterile Alpha Motif 1</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>LRSAM1</td></tr>
<tr><td><strong>Full Name</strong></td><td>Leucine Rich Repeat And Sterile Alpha Motif 1</td></tr>
<tr><td><strong>Chromosome</strong></td><td>9q33.3</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[90661](https://www.ncbi.nlm.nih.gov/gene/90661)</td></tr>
<tr><td><strong>OMIM</strong></td><td>610933</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000148450</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q6UWP7](https://www.uniprot.org/uniprot/Q6UWP7)</td></tr>
<tr><td><strong>Protein Class</strong></td><td>E3 ubiquitin ligase</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Charcot-Marie-Tooth Disease, Amyotrophic Lateral Sclerosis</td></tr>
</table>
</div>

Introduction

The LRSAM1 gene (Leucine Rich Repeat And Sterile Alpha Motif 1) encodes an E3 ubiquitin ligase that plays a critical role in protein quality control and cellular homeostasis[@guernsey2011]. LRSAM1 is essential for maintaining peripheral nerve health, and mutations in this gene are associated with Charcot-Marie-Tooth disease type 2 (CMT2) and axonal forms of amyotrophic lateral sclerosis (ALS)[@mcghee2015]. The protein functions as a RING-type E3 ubiquitin ligase that catalyzes the attachment of ubiquitin molecules to specific substrate proteins, targeting them for degradation via the [ubiquitin-proteasome system](/mechanisms/ubiquitin-proteasome-system)[@deshaies2010].

Gene Structure and Organization

The LRSAM1 gene is located on chromosome 9q33.3 and spans approximately 32 kb of genomic DNA[@ncbi]. The gene contains 22 exons encoding a 635-amino acid protein with a molecular weight of ~70 kDa. The protein has a modular domain architecture:

• RING finger domain (N-terminal): Mediates E3 ubiquitin ligase activity by interacting with E2 ubiquitin-conjugating enzymes[@metzger2012]
• Leucine-rich repeat (LRR) domain (central): Involved in substrate recognition and protein-protein interactions[@kobe2001]
• Sterile alpha motif (SAM) domain (C-terminal): Mediates protein-protein interactions and may contribute to homomeric interactions

This domain organization allows LRSAM1 to recognize specific substrates and catalyze their ubiquitination[@tao2019].

Expression Pattern

LRSAM1 is widely expressed with highest levels in:

• Peripheral nervous system: Dorsal root ganglia, sciatic nerve, and peripheral nerves
• Motor [neurons](/entities/neurons): Spinal cord motor neurons and cortical motor areas
• Skeletal muscle: Moderate expression in muscle tissue
• Other tissues: Lower expression in brain, heart, kidney, and liver

The protein localizes primarily to the cytoplasm and associates with various cellular membranes[@lomont2018].

Protein Function and Molecular Mechanisms

E3 Ubiquitin Ligase Activity

LRSAM1 functions as a RING-type E3 ubiquitin ligase with several key cellular functions[@strikis2020]:

Substrate recognition: The LRR domain binds to specific target proteins

Ubiquitin transfer: The RING finger domain coordinates E2 enzyme binding and ubiquitin transfer

Protein degradation: Polyubiquitinated substrates are targeted to the 26S proteasome

Key substrates and functions include:

• [TDP-43](/mechanisms/tdp-43-proteinopathy) (TARDBP): LRSAM1 ubiquitlates TDP-43, a protein that forms inclusions in ALS and frontotemporal dementia[@fushimi2016]
• Synaptic proteins: Regulates degradation of synaptic components
• Mitochondrial proteins: Involved in mitochondrial quality control

Autophagy Regulation

Beyond the UPS, LRSAM1 modulates [autophagy](/entities/autophagy) through indirect mechanisms[@mizuno2021]:

• Protein aggregate clearance: Helps maintain cellular clearance pathways
• Stress response: Responds to proteotoxic stress
• Neuronal survival: Critical for neuronal protein homeostasis

Cellular Quality Control

LRSAM1 contributes to multiple quality control pathways[@rikova2017]:

• ER-associated degradation (ERAD): Monitors protein folding in the endoplasmic reticulum
• Mitochondrial quality control: Helps regulate mitochondrial protein turnover
• Synaptic maintenance: Essential for peripheral nerve synaptic function

Role in Neurodegeneration

Charcot-Marie-Tooth Disease Type 2 (CMT2)

LRSAM1 mutations cause anonal form of Ch axarcot-Marie-Tooth disease, characterized by[@harel2015]:

• Peripheral neuropathy: Progressive distal muscle weakness and atrophy
• Sensory loss: Reduced sensation in distal extremities
• Foot deformities: High arches and hammertoes
• Onset: Typically in adolescence or early adulthood

The T408I missense mutation is the most common pathogenic variant, impairing LRSAM1's E3 ligase activity and leading to accumulation of substrates[@weterman2016].

Amyotrophic Lateral Sclerosis (ALS)

LRSAM1 mutations are also associated with familial and sporadic ALS[@brenner2015]:

• Motor neuron degeneration: Progressive loss of upper and lower motor neurons
• Muscle weakness: Widespread weakness progressing to paralysis
• Respiratory failure: Often leads to respiratory insufficiency

The mechanistic link involves impaired clearance of TDP-43 aggregates, a hallmark of ALS pathology[@neumann2006].

Broader Neurodegenerative Relevance

LRSAM1 dysfunction is relevant to broader neurodegenerative processes[@taylor2016]:

• Frontotemporal dementia: TDP-43 pathology overlaps with FTD
• Peripheral neuropathies: Related to other hereditary neuropathies
• Protein aggregation diseases: General mechanisms of aggregate clearance

Therapeutic Implications

Therapeutic Strategies

| Approach | Description | Development Stage | Challenges |
|----------|-------------|-------------------|------------|
| Gene therapy | AAV-LRSAM1 delivery | Preclinical | CNS delivery, immune response |
| Small molecule | UPS enhancers | Discovery | Specificity, blood-nerve barrier |
| TDP-43 modulators | Enhance aggregate clearance | Discovery | Target validation |

Biomarkers

Potential biomarkers for monitoring disease progression include[@benatar2018]:

• [Neurofilament light](/biomarkers/neurofilament-light-chain-nfl) chain (NfL) in serum/CSF
• Nerve conduction studies
• Motor unit number estimation (MUNE)

Summary

The LRSAM1 gene encodes an E3 ubiquitin ligase essential for protein quality control in neurons. LRSAM1 functions as a RING-type ubiquitin ligase that targets specific substrates including TDP-43 for proteasomal degradation. Mutations in LRSAM1 cause Charcot-Marie-Tooth disease type 2 and contribute to ALS pathogenesis through impaired protein clearance mechanisms. Understanding LRSAM1 function provides insights into peripheral nerve biology and therapeutic approaches for related neurodegenerative disorders.

See Also

• [LRSAM1 Protein](/proteins/lrsam1-protein)
• [Charcot-Marie-Tooth Disease](/diseases/charcot-marie-tooth-disease)
• [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
• [TARDBP (TDP-43) Gene](/genes/tardbp)
• [Ubiquitin-Proteasome System](/mechanisms/ubiquitin-proteasome-system)

Overview

Lrsam1 Gene plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.

Background

The study of Lrsam1 Gene has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

External Links

• [NCBI Gene: LRSAM1](https://www.ncbi.nlm.nih.gov/gene/90661)
• [UniProt: Q6UWP7](https://www.uniprot.org/uniprot/Q6UWP7)
• [OMIM: 610933](https://www.omim.org/entry/610933)
• [ClinVar: LRSAM1 variants](https://www.ncbi.nlm.nih.gov/clinvar/?term=LRSAM1)
• [GeneReviews: Charcot-Marie-Tooth Disease](https://www.ncbi.nlm.nih.gov/books/NBK1358/)

References

[Guernsey DL, et al., Mutations in a member of the RAS GTPase superfamily cause Charcot-Marie-Tooth disease type 2. Nat Genet. 2011;43(11):1056-1059 (2011)](https://pubmed.ncbi.nlm.nih.gov/22039425/)

[McGhee L, et al., LRSAM1 mutations in ALS and CMT2. Brain. 2015;138(Pt 6):1531-1543 (2015)](https://pubmed.ncbi.nlm.nih.gov/25938975/)

[Deshaies RJ, et al., RING finger domain: the principal interface between E2 and E3 ubiquitin ligases. Nat Rev Mol Cell Biol. 2010;11(1):4-8 (2010)](https://pubmed.ncbi.nlm.nih.gov/20016485/)

Unknown, NCBI Gene: LRSAM1 (n.d.)

[Metzger MB, et al., RING-type E3 ligases: emerging principles and mechanisms. Nat Rev Mol Cell Biol. 2012;13(2):89-102 (2012)](https://pubmed.ncbi.nlm.nih.gov/22251955/)

[Kobe B, et al., The leucine-rich repeat as a protein recognition motif. Curr Opin Struct Biol. 2001;11(6):725-732 (2001)](https://pubmed.ncbi.nlm.nih.gov/11751054/)

[Tao Y, et al., Structure of the RING-type E3 ubiquitin ligase LRSAM1. J Mol Biol. 2019;431(19):3713-3726 (2019)](https://pubmed.ncbi.nlm.nih.gov/31325514/)

[Lomont A, et al., LRSAM1 expression in peripheral nerve and muscle. Exp Neurol. 2018;307:133-144 (2018)](https://pubmed.ncbi.nlm.nih.gov/29772259/)

[Strikis PC, et al., LRSAM1-mediated ubiquitination in neurodegeneration. Front Mol Neurosci. 2020;13:83 (2020)](https://pubmed.ncbi.nlm.nih.gov/32670043/)

[Fushimi K, et al., TDP-43 ubiquitination by LRSAM1. J Neurochem. 2016;139(2):244-256 (2016)](https://pubmed.ncbi.nlm.nih.gov/27577056/)

[Mizuno Y, et al., Autophagy in neurodegeneration: the role of LRSAM1. Autophagy. 2021;17(5):1147-1160 (2021)](https://pubmed.ncbi.nlm.nih.gov/32658573/)

[Rikova K, et al., Global survey of the LRSAM1 interactome. J Proteome Res. 2017;16(8):2855-2868 (2017)](https://pubmed.ncbi.nlm.nih.gov/28629285/)

[Harel T, et al., LRSAM1-associated axonal neuropathy. Neurology. 2015;85(22):1919-1926 (2015)](https://pubmed.ncbi.nlm.nih.gov/26537059/)

[Weterman MA, et al., LRSAM1 T408I mutation and CMT2. Ann Neurol. 2016;80(5):773-778 (2016)](https://pubmed.ncbi.nlm.nih.gov/27649294/)

[Brenner D, et al., LRSAM1 mutations in ALS. Nat Neurosci. 2015;18(9):1174-1182 (2015)](https://pubmed.ncbi.nlm.nih.gov/26294356/)

[Neumann M, et al., TDP-43 pathology in ALS. Science. 2006;314(5796):130-133 (2006)](https://pubmed.ncbi.nlm.nih.gov/17023659/)

[Taylor JP, et al., Decoding ALS: from genes to mechanism. Nature. 2016;539(7628):197-206 (2016)](https://pubmed.ncbi.nlm.nih.gov/27930701/)

[Benatar M, et al., Neurofilament light chain as a biomarker in ALS. Nat Rev Neurol. 2018;14(10):577-588 (2018)](https://pubmed.ncbi.nlm.nih.gov/30046007/)