MLST8 Protein

MLST8 Protein

Introduction

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">MLST8 Protein</th>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>MLST8 (LST8 Homolog)</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>MLST8</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9BVA0</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>326 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>36 kDa</td>
</tr>
<tr>
<td class="label">Cellular Location</td>
<td>Lysosomal membrane, cytoplasm</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>LST8/MLST8 family, WD40 repeat proteins</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Ubiquitous; highest in brain, heart, skeletal muscle</td>
</tr>
<tr>
<td class="label">Finding</td>
<td>Evidence</td>
</tr>
<tr>
<td class="label">Elevated mTORC1 activity in AD brain</td>
<td>PMID: 25396082(https://pubmed.ncbi.nlm.nih.gov/25396082/)</td>
</tr>
<tr>
<td class="label">Impaired autophagy in AD [neurons](/entities/neurons)</td>
<td>PMID: 26255403(https://pubmed.ncbi.nlm.nih.gov/26255403/)</td>
</tr>
<tr>
<td class="label">Synaptic plasticity deficits</td>
<td>PMID: 25926442(https://pubmed.ncbi.nlm.nih.gov/25926442/)</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Complex</td>
</tr>
<tr>
<td class="label">mTOR</td>
<td>mTORC1/mTORC2</td>
</tr>
<tr>

MLST8 Protein

Introduction

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">MLST8 Protein</th>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>MLST8 (LST8 Homolog)</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>MLST8</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9BVA0</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>326 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>36 kDa</td>
</tr>
<tr>
<td class="label">Cellular Location</td>
<td>Lysosomal membrane, cytoplasm</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>LST8/MLST8 family, WD40 repeat proteins</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Ubiquitous; highest in brain, heart, skeletal muscle</td>
</tr>
<tr>
<td class="label">Finding</td>
<td>Evidence</td>
</tr>
<tr>
<td class="label">Elevated mTORC1 activity in AD brain</td>
<td>PMID: 25396082(https://pubmed.ncbi.nlm.nih.gov/25396082/)</td>
</tr>
<tr>
<td class="label">Impaired autophagy in AD [neurons](/entities/neurons)</td>
<td>PMID: 26255403(https://pubmed.ncbi.nlm.nih.gov/26255403/)</td>
</tr>
<tr>
<td class="label">Synaptic plasticity deficits</td>
<td>PMID: 25926442(https://pubmed.ncbi.nlm.nih.gov/25926442/)</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Complex</td>
</tr>
<tr>
<td class="label">mTOR</td>
<td>mTORC1/mTORC2</td>
</tr>
<tr>
<td class="label">RPTOR</td>
<td>mTORC1</td>
</tr>
<tr>
<td class="label">DEPDC5</td>
<td>mTORC1</td>
</tr>
<tr>
<td class="label">PRAS40</td>
<td>mTORC1</td>
</tr>
<tr>
<td class="label">RICTOR</td>
<td>mTORC2</td>
</tr>
<tr>
<td class="label">PROTOR1/2</td>
<td>mTORC2</td>
</tr>
<tr>
<td class="label">Agent</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">Rapamycin (Sirolimus)</td>
<td>Allosteric mTORC1 inhibitor</td>
</tr>
<tr>
<td class="label">Everolimus</td>
<td>Rapamycin analog</td>
</tr>
<tr>
<td class="label">Torin 1</td>
<td>ATP-competitive mTOR inhibitor</td>
</tr>
<tr>
<td class="label">AZD8055</td>
<td>ATP-competitive mTOR inhibitor</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/fibrosis" style="color:#ef9a9a">Fibrosis</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">171 edges</a></td>
</tr>
</table>

Pathway Diagram

Mlst8 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

MLST8 (MTOR Associated Protein, LST8 Homolog) is a conserved 326-amino acid protein that serves as a core structural component of both the mechanistic target of rapamycin complex 1 (mTORC1) and [mTOR](/entities/mtor) complex 2 (mTORC2) [@hara2002]. As a member of the LST8/MLST8 family, MLST8 plays essential roles in stabilizing these multi-protein kinase complexes and modulating their activity through protein-protein interactions [@kim2002]. The mTOR pathway is critically implicated in neurodegenerative diseases, making MLST8 an important therapeutic target [@perluigi2015].

Protein Information

Structure

The MLST8 protein adopts a characteristic beta-propeller fold composed of seven WD40 repeat domains [@tatebe2010]:

• WD40 Repeats (1-7): Each repeat forms a conserved ~44 amino acid motif ending with tryptophan-aspartic acid (WD)
• Beta-Propeller Structure: The seven repeats arrange radially to form a seven-bladed propeller
• Phosphorylation Sites: Multiple serine/threonine phosphorylation sites regulate protein interactions
• Binding Interfaces: The propeller structure provides multiple surfaces for protein-protein interactions with mTOR and other partners

Molecular Function

MLST8 serves multiple structural and regulatory functions within the mTOR signaling network [@laplante2012]:

mTORC1 Component

• Structural Stabilization: MLST8 directly binds to the FKBP12-rapamycin binding (FRB) domain of mTOR, stabilizing the kinase domain
• Subunit Organization: Forms a critical bridge between mTOR and other core components (RPTOR, PRAS40)
• Kinase Activity Modulation: Enhances mTORC1 catalytic activity toward substrates including S6K1 and 4E-BP1

mTORC2 Component

• Complex Assembly: Essential for proper mTORC2 assembly and stability
• Kinase Activation: Required for mTORC2 autophosphorylation and activation
• Akt Signaling: MLST8-containing mTORC2 phosphorylates Akt at Ser473, a critical modification for full Akt activation

Signaling Integration

• Nutrient Sensing: MLST8 helps integrate amino acid and growth factor signals
• mRNA Translation: Coordinates cap-dependent translation through S6K1/4E-BP1
• [Autophagy](/entities/autophagy) Regulation: Links mTORC1 activity to autophagy induction

Biological Functions

Cellular Processes

• Protein Synthesis: Regulation of ribosomal biogenesis and mRNA translation through S6K1 and 4E-BP1 phosphorylation
• Autophagy: mTORC1-mediated inhibition of autophagy initiation via ULK1 complex phosphorylation
• Cell Growth: Coordinate regulation of cell size, proliferation, and metabolism
• Cytoskeletal Organization: Effects on actin dynamics and cell motility

Tissue-Specific Functions

• Neuronal Functions: Regulation of synaptic plasticity, spine morphology, and neuronal protein synthesis
• Metabolic Functions: Integration of growth factor signaling with metabolic programs
• Developmental Functions: Essential for embryonic development in mice

Disease Mechanisms

Alzheimer's Disease

The mTOR pathway is profoundly dysregulated in Alzheimer's disease, with MLST8 playing a central role [@caccamo2015]:

• mTORC1 Hyperactivation: Reported in AD brains, contributing to impaired autophagy and accumulation of protein aggregates including [amyloid-beta](/proteins/amyloid-beta) and [tau](/proteins/tau) [@crews2010]
• Synaptic Dysfunction: Hyperactive mTORC1 disrupts synaptic plasticity mechanisms, contributing to cognitive deficits [@tang2002]
• Autophagy Impairment: Impaired autophagic-lysosomal pathway leads to accumulation of damaged organelles and protein inclusions [@nixon2013]
• Beta-Ameloid Effects: Amyloid-beta directly activates mTORC1 signaling, creating a vicious cycle [@querfurth2004]

Parkinson's Disease

MLST8 and mTOR signaling are implicated in multiple aspects of PD pathogenesis [@liu2019]:

• Autophagy-Lysosomal Dysfunction: mTORC1 overactivity inhibits autophagy, contributing to [alpha-synuclein](/mechanisms/alpha-synuclein) accumulation [@dehay2010]
• Mitochondrial Dysfunction: mTORC2-Akt signaling regulates mitochondrial health and mitophagy [@murata2011]
• Neuroinflammation: mTOR signaling modulates microglial activation and neuroinflammation [@zhou2011]
• Neuroprotection: mTOR inhibition may provide neuroprotective effects in PD models [@malagelada2010]

Amyotrophic Lateral Sclerosis

• mTOR Dysregulation: Altered mTOR signaling in motor neurons
• Protein Aggregation: Impaired autophagy contributes to protein inclusion formation
• Therapeutic Potential: mTOR inhibitors being explored in preclinical models [@hashimoto2018]

Huntington's Disease

• mTORC1 Hyperactivity: Contributes to transcriptional dysregulation and protein aggregation
• Autophagy Impairment: Loss of autophagic function leads to mutant [huntingtin](/proteins/huntingtin-protein) accumulation
• Therapeutic Targeting: mTOR modulation as a potential intervention [@ravikumar2004]

Protein Interactions

Therapeutic Implications

mTOR Inhibitors

Autophagy Inducers

• Trehalose: Natural disaccharide that induces autophagy independent of mTOR inhibition [@mackin2014]
• Resveratrol: Polyphenol with mTOR-modulating and autophagy-inducing properties [@vingtdeux2010]
• Carbamazepine: Anticonvulsant that induces autophagy through mTOR-independent pathways

Therapeutic Considerations

• [Blood-Brain Barrier](/entities/blood-brain-barrier): Challenge for CNS drug delivery; rapamycin shows limited BBB penetration
• Chronic vs Acute: Chronic mTOR inhibition may have different effects than acute treatment
• Combination Therapy: mTOR inhibitors combined with other agents for enhanced efficacy

Research Directions

• Blood-Brain Barrier Penetrant mTOR Inhibitors: Development of derivatives with improved CNS penetration
• mTORC2-Selective Modulation: Targeting mTORC2 specifically to avoid immunosuppressive effects
• Autophagy-Targeted Approaches: mTOR-independent autophagy induction strategies
• Biomarker Development: Monitoring mTOR pathway activity in patient samples

See Also

• [mTOR Gene](/proteins/mtor-protein) — Mechanistic target of rapamycin
• [RPTOR Gene](/proteins/rptor-protein) — Raptor, mTORC1 component
• [RICOT Gene](/proteins/raptor-protein) — Rictor, mTORC2 component
• [mTOR Signaling Pathway](/mechanisms/mtor-signaling-pathway)
• [Autophagy-Lysosomal Pathway](/mechanisms/autophagy-lysosomal-pathway)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
• [Huntington's Disease](/diseases/huntington-disease)

Background

The study of Mlst8 Protein 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 MLST8](https://www.ncbi.nlm.nih.gov/gene/84916)
• [UniProt Q9BVA0](https://www.uniprot.org/uniprotkb/Q9BVA0)
• [PhosphoSitePlus MLST8](https://www.phosphosite.org/proteinAction?id=3845&showAllSites=true)

References