XIAP — X-Linked Inhibitor of Apoptosis
Introduction
Xiap is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
<div class="infobox infobox-gene"> [@eckhart2002]
<table> [@fulda2009]
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">X-Linked Inhibitor of Apoptosis</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>XIAP</td></tr>
<tr><td><strong>Full Name</strong></td><td>X-Linked Inhibitor of Apoptosis</td></tr>
<tr><td><strong>Chromosome</strong></td><td>Xq25</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[331](https://www.ncbi.nlm.nih.gov/gene/331)</td></tr>
<tr><td><strong>OMIM</td><td>300079</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000101966</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[P98170](https://www.uniprot.org/uniprot/P98170)</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Alzheimer's Disease, Parkinson's Disease, X-linked Spinal Muscular Atrophy</td></tr>
</table>
</div>
Overview
...XIAP — X-Linked Inhibitor of Apoptosis
Introduction
Xiap is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
<div class="infobox infobox-gene"> [@eckhart2002]
<table> [@fulda2009]
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">X-Linked Inhibitor of Apoptosis</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>XIAP</td></tr>
<tr><td><strong>Full Name</strong></td><td>X-Linked Inhibitor of Apoptosis</td></tr>
<tr><td><strong>Chromosome</strong></td><td>Xq25</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[331](https://www.ncbi.nlm.nih.gov/gene/331)</td></tr>
<tr><td><strong>OMIM</td><td>300079</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000101966</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[P98170](https://www.uniprot.org/uniprot/P98170)</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Alzheimer's Disease, Parkinson's Disease, X-linked Spinal Muscular Atrophy</td></tr>
</table>
</div>
Overview
XIAP (X-Linked Inhibitor of Apoptosis) is a potent anti-apoptotic protein that directly inhibits caspases-3, -7, and -9, making it a key regulator of programmed cell death. Unlike other IAP family members, XIAP contains three baculovirus IAP repeat (BIR) domains that confer caspase inhibitory activity, as well as a RING domain with E3 ubiquitin ligase function. XIAP is widely expressed in neuronal tissues where it protects against [apoptosis](/entities/apoptosis) induced by various stimuli including oxidative stress, mitochondrial dysfunction, and excitotoxicity. Its dysregulation is implicated in cancer progression and neurodegenerative diseases.
Function
XIAP (X-linked Inhibitor of Apoptosis) is the best-characterized member of the Inhibitor of Apoptosis (IAP) protein family. XIAP directly binds to and inhibits caspases-3, -7, and -9, preventing the execution of apoptosis. It contains three baculovirus IAP repeat (BIR) domains that mediate caspase binding and inhibition.
In [neurons](/entities/neurons), XIAP plays a crucial neuroprotective role by inhibiting caspase activity. It is downregulated in several neurodegenerative diseases, contributing to increased neuronal vulnerability to apoptotic stimuli. XIAP also has caspase-independent functions in cell survival signaling through [NF-κB](/entities/nf-kb) activation.
Expression
XIAP is widely expressed in most tissues, including the brain. In the nervous system, it is expressed in neurons and glia. Its expression can be upregulated by survival signals including neurotrophic factors, while pro-apoptotic signals can downregulate XIAP expression.
Disease Associations
| Disease | Variants | Inheritance | Mechanism |
|---------|----------|-------------|-----------|
| Alzheimer's Disease | Reduced expression | Acquired | Loss of caspase inhibition leads to neuronal apoptosis |
| Parkinson's Disease | Reduced expression | Acquired | Increased dopaminergic neuron death |
| X-linked SMA | Mutations | X-linked | XIAP deficiency causes motor neuron degeneration |
| Cancer | Overexpression | Somatic | Blocks apoptosis, allowing tumor survival |
Therapeutic Implications
- XIAP mimetics (Smac mimetics) in cancer clinical trials
- XIAP upregulation strategies for neuroprotection
- Gene therapy to increase XIAP expression in neurons
Key Publications
[10358769](https://pubmed.ncbi.nlm.nih.gov/10358769/): XIAP structure and function. Cell, 1999.
[12121969](https://pubmed.ncbi.nlm.nih.gov/12121969/): XIAP in neurodegeneration. Nat Rev Neurosci, 2002.
[19643035](https://pubmed.ncbi.nlm.nih.gov/19643035/): XIAP and caspase inhibition. Nat Rev Drug Discov, 2009.See Also
- [CASP3](/genes/casp3)
- [CASP9](/genes/casp9)
- [Apoptosis Pathways](/mechanisms/apoptosis-neuronal)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
Background
The study of Xiap 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
- [PubMed](https://pubmed.ncbi.nlm.nih.gov/) - Biomedical literature
- [Alzheimer's Disease Neuroimaging Initiative](https://adni.loni.usc.edu/) - Research data
- [Allen Brain Atlas](https://brain-map.org/) - Brain gene expression data
References
Unknown, Shi Y. (2002). Mechanisms of caspase activation and inhibition. Cell 108: 755-766 (2002)
Eckhart L, et al., (2002). XIAP and caspase inhibition. Nat Rev Neurosci 3: 663-664 (2002)
Fulda S, et al., (2009). Targeting IAP proteins for cancer therapy. Nat Rev Drug Discov 8: 153-168 (2009)Pathway Diagram
The following diagram shows the key molecular relationships involving XIAP discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)
Pathway Diagram
The following diagram shows the key molecular relationships involving XIAP discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)