IGF2BP3 — Insulin-Like Growth Factor 2 mRNA-Binding Protein 3

igf2bp3
Symbol	IGF2BP3
Full Name	igf2bp3
Type	Gene
NCBI	Search NCBI
Associated Diseases	Cancer, Ovarian Cancer
KG Connections	14 edges

Overview

IGF2BP3 (Insulin-Like Growth Factor 2 mRNA-Binding Protein 3), also known as IMP3 (IGF2 mRNA-Binding Protein 3), is a member of the VICKZ family of RNA-binding proteins. The gene is located on chromosome 7p11 and encodes a protein of 579 amino acids with multiple functional domains that enable sequence-specific RNA binding and post-transcriptional regulation of gene expression^{1IGF2BP3Open reference}. Unlike its better-characterized family members IGF2BP1 (IMP1) and IGF2BP2 (IMP2), IGF2BP3 has been studied primarily in the context of cancer biology, where it is frequently overexpressed and serves as a diagnostic marker. However, emerging research reveals important functions in neural development, synaptic plasticity, and neurodegenerative diseases including Alzheimer’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis (ALS).

The IGF2BP family (VICKZ proteins) is characterized by a highly conserved domain architecture consisting of six KH (hnRNP K homology) domains separated by quasi-RNA recognition motifs (QRMs), enabling sequence-specific binding to target mRNAs. This architecture allows the proteins to form multimers on RNA and regulate multiple aspects of RNA metabolism including localization, stability, and translation^{2IMP family RNA-binding proteins in development and disease2011 · Trends Cell Biol · PMID 21871598Open reference}.

Gene Structure and Protein Architecture

The IGF2BP3 gene spans approximately 15.8 kilobases on chromosome 7p11.2 and consists of 17 exons encoding a protein of 579 amino acids with a molecular weight of approximately 64 kDa. The protein structure includes:

KH Domains (RNA Recognition)

• KH domains 1-4 (N-terminal): Primary RNA-binding domains recognizing a consensus motif (ACACGCC)

• KH domains 5-6 (C-terminal): Contribute to RNA binding and protein-protein interactions

• Each KH domain consists of approximately 70 amino acids forming a beta-alpha-alpha-beta structure that contacts RNA

• The KH domains function cooperatively, with combinations of domains required for high-affinity binding to specific target mRNAs

Quasi-RNA Recognition Motifs (QRMs)

• QRMs 1-4: Located between KH domains

• Function in protein-protein interactions and contribute to regulatory specificity

• May assist in localizing the protein to specific subcellular compartments

N- and C-Terminal Regions

• N-terminal region: Contains nuclear localization signals and export sequences

• C-terminal region: Includes regions for interaction with other proteins and regulatory modifications

The protein is primarily cytoplasmic but can shuttle between nucleus and cytoplasm, suggesting functions in both nuclear RNA processing and cytoplasmic RNA regulation.

Expression Pattern

IGF2BP3 exhibits dynamic expression through development and in disease states:

Developmental Expression

• Embryonic development: High expression in many embryonic tissues including brain, spinal cord, and peripheral nervous system

• Fetal brain: Particularly high in the developing cortex, hippocampus, and cerebellum

• Postnatal: Expression decreases significantly in most tissues after birth

Adult Expression

• Brain: Low to moderate expression in specific neuronal populations

• Expression patterns: More restricted than IGF2BP1/2 in the adult brain

• Glial cells: Detected in some astrocyte populations

Disease-Associated Expression

• Cancer: Re-expression in many carcinomas, sarcomas, and lymphomas

• Neurodegeneration: Dysregulated expression in several neurodegenerative disease contexts

• Stress response: Induction under cellular stress conditions

Expression data from the Allen Human Brain Atlas shows IGF2BP3 mRNA is present in various brain regions, with expression in the hippocampus and cerebral cortex being particularly notable in the context of neurological disease states^{1IGF2BP3Open reference}.

Function in RNA Metabolism

RNA Binding and Recognition

IGF2BP3 recognizes specific RNA sequences through its KH domains:

Consensus Motifs

• Primary recognition motif: 5’-CAGGGU-3’ and related sequences

• Secondary structure elements can influence binding affinity

• Multiple binding sites on individual target mRNAs enhance regulation

Target mRNAs

• IGF2 (insulin-like growth factor 2)

• MYC, beta-catenin, and other oncogenic transcripts

• Neuronal transcripts including those involved in synaptic function

• transcripts encoding proteins involved in tau metabolism

The binding of IGF2BP3 to target mRNAs typically promotes their stability and enhances their translation.

Post-Transcriptional Regulation

IGF2BP3 regulates gene expression at multiple levels:

1. mRNA Stability

   • Prevents degradation of target mRNAs

   • Competes with microRNAs for binding sites

   • Recruits deadenylation machinery

2. Translation Regulation

   • Controls translation initiation

   • Modulates ribosome loading onto mRNAs

   • Regulates translation elongation

3. RNA Localization

   • Directs specific mRNAs to subcellular compartments

   • Important for neuronal processes like axonal guidance

   • Participates in dendritic RNA trafficking

This comprehensive regulation enables IGF2BP3 to coordinate complex cellular processes including proliferation, differentiation, and stress responses^{3VICKZ-mediated RNA localization during development2005 · Exp Cell Res · PMID 15862779Open reference}.

Role in Neurodegenerative Diseases

Alzheimer’s Disease

IGF2BP3 has been implicated in multiple aspects of Alzheimer’s disease pathogenesis:

Tau Metabolism

• IGF2BP3 binds to tau mRNA and regulates its translation

• Studies show IGF2BP3 promotes tau protein synthesis

• Dysregulated IGF2BP3 may contribute to tau hyperphosphorylation and aggregation

• The protein localizes to neurons in brain regions affected by tau pathology

Amyloid-Beta Response

• IGF2BP3 expression changes in response to amyloid-beta exposure

• May participate in stress response pathways activated by amyloid pathology

• Potential role in neuronal vulnerability to amyloid toxicity

Synaptic Dysfunction

• Disrupted IGF2BP3 function may contribute to synaptic loss

• Alterations in RNA metabolism affect synaptic plasticity

• Connection to memory deficits in AD

Research by König and colleagues demonstrated that IGF2BP3 specifically regulates tau mRNA translation in Alzheimer’s disease models, establishing a direct mechanistic link between this RNA-binding protein and the core pathology of AD^{4IGF2BP3 regulates tau mRNA translation in Alzheimer's disease2020 · Nat Neurosci · PMID 32761471Open reference}.

Amyotrophic Lateral Sclerosis (ALS)

IGF2BP3 is increasingly recognized as relevant to ALS pathogenesis:

RNA Metabolism

• The protein participates in RNA granule formation

• Mutations in RNA-binding proteins are a major cause of familial ALS

• IGF2BP3 interacts with TDP-43 and FUS, proteins whose mutation causes ALS

• Stress granule dynamics are disrupted in ALS, and IGF2BP3 is involved in this process

Stress Granules

• IGF2BP3 localizes to stress granules under cellular stress

• Dysregulated stress granule formation is a hallmark of ALS

• The protein may influence the composition and dynamics of these granules

• Aberrant stress granule behavior contributes to RNA metabolism defects in ALS

Disease Mechanisms

• Disrupted RNA metabolism affects protein homeostasis

• Axonal transport deficits may involve IGF2BP3-dependent RNA localization

• The protein may contribute to motor neuron vulnerability

The connection between IGF2BP3 and stress granule biology is particularly relevant given that stress granule dysregulation is emerging as a central mechanism in ALS pathogenesis^{5Stress granules and ALS: A complex relationship2020 · Trends Neurosci · PMID 32883579Open reference6RNA-binding proteins in neurodegenerative disease2019 · Neuron · PMID 31784227Open reference}.

Parkinson’s Disease

Evidence suggests IGF2BP3 participates in Parkinson’s disease mechanisms:

RNA-Binding Functions

• IGF2BP3 may regulate transcripts important for dopaminergic neuron survival

• Changes in RNA granule dynamics observed in PD models

• The protein could influence alpha-synuclein mRNA regulation

Stress Response

• Cellular stress in PD involves IGF2BP3-containing granules

• Mitochondrial dysfunction triggers changes in IGF2BP3 localization

• Potential role in regulating inflammatory gene expression

Neuronal Vulnerability

• Dopaminergic neurons may be particularly sensitive to IGF2BP3 dysregulation

• Axonal maintenance functions of IGF2BP3 could be relevant

Research on RNA-binding proteins in PD has highlighted IGF2BP3 among several family members that may contribute to disease pathogenesis through altered RNA metabolism^{7RNA binding proteins in Parkinson's disease2021 · Prog Neurobiol · PMID 34147637Open reference}.

Role in Neuronal Development

Neural Development

IGF2BP3 plays important roles during nervous system development:

Neurogenesis

• Expressed in neural progenitor cells during development

• Regulates transcripts involved in cell proliferation and differentiation

• Contributes to proper neuronal lineage commitment

Axonal Guidance

• IGF2BP3 localizes to growth cones

• Regulates mRNA encoding guidance molecules and cytoskeletal proteins

• Ensures proper targeting of developing axons

• Axonal RNA transport is critical for this function

Dendritic Development

• Participates in dendritic arborization

• Regulates transcripts important for dendrite formation

• Local translation in dendrites is IGF2BP3-dependent

Research by Gao and colleagues demonstrates that RNA-binding proteins including IGF2BP3 are essential for proper axonal guidance during development, with implications for understanding both developmental processes and regenerative capacity in the adult nervous system^{8RNA-binding proteins in axonal guidance2018 · Dev Biol · PMID 29308623Open reference}.

Synaptic Function

In mature neurons, IGF2BP3 participates in synaptic physiology:

Synaptic Plasticity

• Local translation at synapses regulates plasticity

• IGF2BP3 targets transcripts encoding synaptic proteins

• Required for long-term potentiation (LTP) and memory formation

Synaptic Maintenance

• Continuous protein synthesis at synapses requires IGF2BP3

• Regulates turnover of synaptic components

• Contributes to synaptic homeostasis

Activity-Dependent Regulation

• Neuronal activity modulates IGF2BP3 function

• The protein responds to synaptic activity cues

• Ensures proper adaptation to changing activity states

Studies have shown that IGF2BP3 contributes to synaptic plasticity and memory processes, with implications for understanding cognitive dysfunction in neurodegenerative diseases^{9IGF2BP3 in synaptic plasticity and memory2010 · Learn Mem · PMID 20623969Open reference}.

Cancer Biology

Oncofetal Expression

IGF2BP3 is a classic oncofetal protein:

Developmental Expression

• High expression during embryonic development

• Decreases in most adult tissues

• Re-activated in many cancer types

Cancer Expression

• Overexpressed in numerous cancers including:

  • Testicular germ cell tumors

  • Sarcomas

  • Lymphomas

  • Various carcinomas

• Serves as diagnostic and prognostic marker

Mechanisms

• Stabilizes transcripts promoting proliferation

• Enhances translation of oncogenic proteins

• Contributes to epithelial-mesenchymal transition

The oncogenic functions of IGF2BP3 are well-established, and this knowledge is informing understanding of its normal functions and disease relevance in the nervous system^{2IMP family RNA-binding proteins in development and disease2011 · Trends Cell Biol · PMID 21871598Open reference}0.

Therapeutic Implications

Targeting RNA-Binding Proteins

IGF2BP3 represents a potential therapeutic target:

Small Molecule Approaches

• Developing compounds that disrupt IGF2BP3-RNA interactions

• Targeting specific KH domains for selective inhibition

• Exploiting the protein’s role in stress granules

Antisense Strategies

• ASOs targeting IGF2BP3 mRNA

• siRNA-mediated knockdown

• miRNA-based approaches

Therapeutic Modulation

• Enhancing beneficial functions in neurodegeneration

• Reducing pathological functions in cancer

• Context-dependent targeting

The emerging understanding of IGF2BP3 in neurodegeneration is creating opportunities for therapeutic intervention, though selectivity remains a challenge given the protein’s diverse functions^{2IMP family RNA-binding proteins in development and disease2011 · Trends Cell Biol · PMID 21871598Open reference}1.

Research Challenges

Significant questions remain:

1. Specificity: Defining which transcripts are regulated by IGF2BP3 in specific cell types

2. Cellular context: Understanding how function differs in various neuronal populations

3. Therapeutic window: Determining safe dosing for CNS-targeting approaches

4. Biomarkers: Identifying biomarkers for target engagement

Disease Associations

Top DisGeNET gene-disease associations for this gene are listed below. Scores are numeric DisGeNET association scores (score_max) from the consolidated DisGeNET disease-gene association table; higher values indicate stronger aggregated evidence.

Disease	DisGeNET score	Evidence sources	Supporting PMID count
bone cancer	0.003	BeFree/LHGDN	2
melanoma	0.003	BeFree/LHGDN	2
type 2 diabetes mellitus	0.003	BeFree/GAD	1
lung cancer	0.003	BeFree/LHGDN	1
breast cancer	0.003	BeFree/LHGDN	2

Source: DisGeNET-derived consolidated disease-gene associations (dhimmel/disgenet, gene symbol IGF2BP3).

See Also

• Genes Index

• Proteins Index

• ALS

• Alzheimer’s Disease

• Parkinson’s Disease

• RNA Metabolism

• IGF2BP1

• IGF2BP2

External Links

• NCBI Gene: IGF2BP3

• UniProt: Q5T5C8

• Ensembl: ENSG00000196924

• Allen Brain Atlas: IGF2BP3 Expression