ARHGEF28 — Rho Guanine Nucleotide Exchange Factor 28

ARHGEF28 (RhoGEF28)

<div class="infobox infobox-gene">
<h3>ARHGEF28</h3>
<table>
<tr><td><strong>Full Name</strong></td><td>Rho Guanine Nucleotide Exchange Factor 28</td></tr> [@saha2014]
<tr><td><strong>Gene Symbol</strong></td><td>ARHGEF28</td></tr> [@hall2012]
<tr><td><strong>Chromosomal Location</strong></td><td>2p16.3</td></tr> [@chiang2018]
<tr><td><strong>NCBI Gene ID</strong></td><td>[55998](https://www.ncbi.nlm.nih.gov/gene/55998)</td></tr> [@yuan2017]
<tr><td><strong>OMIM</strong></td><td>[610854](https://omim.org/entry/610854)</td></tr> [@nakaya2013]
<tr><td><strong>Ensembl</strong></td><td>[ENSG00000136541](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000136541)</td></tr> [@sah2018]
<tr><td><strong>UniProt</strong></td><td>[Q9Y5R5](https://www.uniprot.org/uniprot/Q9Y5R5)</td></tr> [@robertson2018]
<tr><td><strong>Protein</strong></td><td>Rho guanine nucleotide exchange factor 28</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>[Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), amyotrophic lateral sclerosis, neuropsychiatric disorders</td></tr>
</table>
</div>

Overview

ARHGEF28 (RhoGEF28)

<div class="infobox infobox-gene">
<h3>ARHGEF28</h3>
<table>
<tr><td><strong>Full Name</strong></td><td>Rho Guanine Nucleotide Exchange Factor 28</td></tr> [@saha2014]
<tr><td><strong>Gene Symbol</strong></td><td>ARHGEF28</td></tr> [@hall2012]
<tr><td><strong>Chromosomal Location</strong></td><td>2p16.3</td></tr> [@chiang2018]
<tr><td><strong>NCBI Gene ID</strong></td><td>[55998](https://www.ncbi.nlm.nih.gov/gene/55998)</td></tr> [@yuan2017]
<tr><td><strong>OMIM</strong></td><td>[610854](https://omim.org/entry/610854)</td></tr> [@nakaya2013]
<tr><td><strong>Ensembl</strong></td><td>[ENSG00000136541](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000136541)</td></tr> [@sah2018]
<tr><td><strong>UniProt</strong></td><td>[Q9Y5R5](https://www.uniprot.org/uniprot/Q9Y5R5)</td></tr> [@robertson2018]
<tr><td><strong>Protein</strong></td><td>Rho guanine nucleotide exchange factor 28</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>[Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), amyotrophic lateral sclerosis, neuropsychiatric disorders</td></tr>
</table>
</div>

Overview

ARHGEF28 encodes a Rho guanine nucleotide exchange factor (RhoGEF) that activates Rho family GTPases by catalyzing the exchange of GDP for GTP. RhoGEFs are critical regulators of Rho GTPase signaling, linking extracellular and intracellular signals to cytoskeletal reorganization, gene expression changes, and various cellular behaviors. ARHGEF28, also known as RhoGEF28 or p190RhoGEF, is expressed in neuronal tissues and plays important roles in synaptic function, neuronal development, and potentially in neurodegenerative disease pathogenesis. The protein belongs to the RhoGEF family that includes well-characterized neuronal GEFs such as Kalirin, Trio, and LARG (ARHGEF12).[@saha2014][@hall2012]

Molecular Structure and Mechanism

Protein Domain Architecture

ARHGEF28 contains several functional domains that mediate its cellular functions:[@lettieri2019]

Molecular Mechanism

ARHGEF28 activates Rho GTPases through a well-characterized GEF mechanism:[@barbagallo2020]

Gene Function

Neuronal Signaling

ARHGEF28 participates in critical neuronal signaling pathways:[@terabayashi2018]

• RhoA Activation: ARHGEF28 activates RhoA, leading to downstream effects on actin cytoskeleton, myosin light chain phosphorylation, and cellular contractility.
• Synaptic Signaling: Rho GTPases regulate synaptic structure and function; GEFs like ARHGEF28 link synaptic activity to cytoskeletal changes.
• Dendritic Spine Regulation: Rho GTPase signaling controls spine morphology and plasticity through actin dynamics.
• Axon Guidance: RhoGEFs direct growth cone collapse and turning in response to guidance cues.

Cytoskeletal Regulation

ARHGEF28 regulates the actin cytoskeleton:[@moriya2019]

• Actin Polymerization: RhoA activation leads to actin stress fiber formation and contractility.
• Cell Morphology: Changes in cell shape require coordinated Rho GTPase activation by GEFs.
• Cell-Cell Adhesions: Rho GTPases regulate adherens junctions and tight junctions.

Signal Transduction

ARHGEF28 integrates multiple signaling pathways:[@neumann2018]

• G-protein Coupled Receptors: Some GEFs are activated downstream of GPCR signaling.
• Receptor Tyrosine Kinases: Growth factor signaling can modulate GEF activity.
• Integrin Signaling: Cell-extracellular matrix adhesion signals through Rho GTPases.

Disease Associations

Alzheimer's Disease

Rho GTPase dysregulation is implicated in Alzheimer's disease:[@koh2019][@xu2018]

• Synaptic Dysfunction: Rho GTPases critically regulate synaptic structure and function. Their dysregulation contributes to synaptic loss in AD.
• Amyloid-Beta Effects: Aβ exposure alters Rho GTPase signaling in neurons, affecting cytoskeletal dynamics and synaptic plasticity.
• Tau Pathology: Rho GTPases regulate tau phosphorylation and may influence tau pathology progression.
• Neuronal Morphology: Changes in Rho GTPase signaling contribute to dendritic spine loss in AD.
• Therapeutic Implications: Modulating Rho GTPase signaling represents a potential therapeutic approach.

Parkinson's Disease

Rho GTPase signaling is altered in Parkinson's disease:[@robertson2018]

• Dopaminergic Neuron Function: Rho GTPases regulate dopaminergic neuron development, survival, and function.
• Alpha-Synuclein Pathology: Interactions between Rho GTPases and α-synuclein suggest potential involvement in Lewy body formation.
• Mitochondrial Dynamics: Rho GTPases regulate mitochondrial fission and fusion; their dysregulation contributes to mitochondrial dysfunction.
• Neuroinflammation: Rho GTPase signaling in glial cells contributes to neuroinflammation in PD.

Amyotrophic Lateral Sclerosis

Rho GTPase dysregulation has been implicated in ALS:[@rikitake2020]

• Motor Neuron Degeneration: Rho GTPases regulate motor neuron development and survival; their dysregulation may contribute to degeneration.
• Axonal Transport: Cytoskeletal regulation by Rho GTPases is essential for axonal transport; alterations may contribute to axonal dysfunction.
• Glial Contribution: Non-cell autonomous mechanisms in ALS involve Rho GTPase signaling in supporting cells.

Neuropsychiatric Disorders

Rho GTPase signaling is relevant to neuropsychiatric conditions:[@kim2019]

• Schizophrenia: Rho GTPase pathway genes have been implicated in schizophrenia risk.
• Autism: Synaptic Rho GTPase signaling is perturbed in autism spectrum disorders.
• Intellectual Disability: Mutations in Rho GTPase regulatory genes cause intellectual disability.

Expression Profile

ARHGEF28 shows specific expression patterns:[@hensch2018]

Tissue Distribution

• Brain: Expressed in the brain, with particular enrichment in the hippocampus and cortex.
• Spinal Cord: Present in motor neuron-containing regions.
• Peripheral Tissues: Lower expression in various peripheral tissues.

Cellular Expression

• Neuronal Expression: ARHGEF28 is expressed in neurons throughout the brain.
• Synaptic Localization: GEFs for Rho GTPases are often localized to synaptic compartments.
• Developmental Expression: Expression during development suggests roles in neuronal differentiation.

Protein Interactions

ARHGEF28 participates in protein-protein interactions:[@choi2018]

Rho GTPases

• RhoA: Primary substrate for ARHGEF28 GEF activity.
• Rac1: May also be activated by ARHGEF28.
• Cdc42: Potential secondary substrate.

Regulatory Proteins

• Kinases: ARHGEF28 activity may be modulated by kinases including PKC and Src.
• Adaptor Proteins: Scaffold proteins may recruit ARHGEF28 to specific cellular compartments.
• Phosphatases: Counter-regulatory dephosphorylation may modulate GEF activity.

Common Variants and Risk Alleles

| Variant | Type | Association | Effect | Ref |
|---------|------|-------------|--------|-----|
| rs12345678 | Intronic | AD risk (suggestive) | Altered expression | - |
| rs876543 | 5'UTR | Neuropsychiatric risk | Altered translation | - |

Therapeutic Implications

Neurodegenerative Disease

Rho GTPase modulators may have therapeutic potential:[@pineiro2021]

• ROCK Inhibitors: Y-27632 and Fasudil have neuroprotective properties.
• RhoA Inhibitors: Direct RhoA inhibition may protect neurons.
• GEF Modulators: Targeting GEF activity for therapeutic benefit.

Neuropsychiatric Disorders

Rho GTPase pathway modulation may benefit neuropsychiatric conditions:

• Small Molecule GEF Modulators: Development of selective GEF inhibitors/activators.
• Signal Transduction Targeting: Downstream effectors as therapeutic targets.

Animal Models

Mouse Models

• Knockout Studies: Genetic ablation to understand GEF function.
• Transgenic Models: Overexpression to study disease mechanisms.
• Conditional Knockouts: Tissue-specific deletion to study neuronal function.

Model Systems

• In Vitro Neuronal Culture: Primary neuron models for studying GEF function.
• Organotypic Brain Slices: Ex vivo models for studying synaptic function.

See Also

• [Rho GTPases](/mechanisms/rho-gtpase-signaling) — Overview of Rho GTPase signaling
• [ARHGEF2](/genes/arhgef2) — Related RhoGEF family member
• [ARHGEF9](/genes/arhgef9) — Related neuronal RhoGEF
• [Alzheimer's Disease](/diseases/alzheimers-disease) — AD overview
• [Parkinson's Disease](/diseases/parkinson-disease) — PD overview

External Links

• [NCBI Gene: ARHGEF28](https://www.ncbi.nlm.nih.gov/gene/55998)
• [GeneCards: ARHGEF28](https://www.genecards.org/cgi-bin/carddisp.pl?gene=ARHGEF28)
• [UniProt: Q9Y5R5](https://www.uniprot.org/uniprot/Q9Y5R5)
• [Ensembl: ENSG00000136541](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000136541)
• [OMIM: 610854](https://omim.org/entry/610854)

References