NLRP7 — NLR Family Pyrin Domain Containing 7

NLRP7 — NLR Family Pyrin Domain Containing 7

Introduction

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">NLRP7 — NLR Family Pyrin Domain Containing 7</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>NLRP7</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>NLR Family Pyrin Domain Containing 7</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>19q13.42</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>[199713](https://www.ncbi.nlm.nih.gov/gene/199713)</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>[609434](https://www.omim.org/entry/609434)</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>[ENSG00000124313](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000124313)</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>[Q8WX94](https://www.uniprot.org/uniprot/Q8WX94)</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>NOD27, CLR19.9</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Gene Symbol</td>
</tr>
<tr>
<td class="label">ASC</td>
<td>PYCARD</td>
</tr>
<tr>
<td class="label">Caspase-1</td>
<td>CASP1</td>
</tr>
<tr>
<td class="label">NLRP3</td>
<td>NLRP3</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Gene Symbol</td>
</tr>
<tr>
<td class="label">NLRP1</td>
<td>NLRP1</td>
</tr>
<tr>
<td class="label">NLRP3</td>
<td>NLRP3</td>
</tr>
<tr>
<td class="label">NLRP6</td>
<td>NLRP6</td>
</tr>
<tr>

NLRP7 — NLR Family Pyrin Domain Containing 7

Introduction

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">NLRP7 — NLR Family Pyrin Domain Containing 7</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>NLRP7</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>NLR Family Pyrin Domain Containing 7</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>19q13.42</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>[199713](https://www.ncbi.nlm.nih.gov/gene/199713)</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>[609434](https://www.omim.org/entry/609434)</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>[ENSG00000124313](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000124313)</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>[Q8WX94](https://www.uniprot.org/uniprot/Q8WX94)</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>NOD27, CLR19.9</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Gene Symbol</td>
</tr>
<tr>
<td class="label">ASC</td>
<td>PYCARD</td>
</tr>
<tr>
<td class="label">Caspase-1</td>
<td>CASP1</td>
</tr>
<tr>
<td class="label">NLRP3</td>
<td>NLRP3</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Gene Symbol</td>
</tr>
<tr>
<td class="label">NLRP1</td>
<td>NLRP1</td>
</tr>
<tr>
<td class="label">NLRP3</td>
<td>NLRP3</td>
</tr>
<tr>
<td class="label">NLRP6</td>
<td>NLRP6</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Gene Symbol</td>
</tr>
<tr>
<td class="label">IL-1β</td>
<td>IL1B</td>
</tr>
<tr>
<td class="label">IL-18</td>
<td>IL18</td>
</tr>
<tr>
<td class="label">IL-33</td>
<td>IL33</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/autoimmune" style="color:#ef9a9a">Autoimmune</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">20 edges</a></td>
</tr>
</table>

NLRP7 (NLR Family Pyrin Domain Containing 7) is a member of the NOD-like receptor (NLR) family of proteins that plays complex roles in innate immunity, inflammation, and cellular homeostasis. While primarily studied in the context of reproductive biology and inflammation, emerging evidence suggests that NLRP7 may have important functions in the nervous system and could contribute to neuroinflammatory processes in neurodegenerative diseases. This gene encodes a protein characterized by an N-terminal pyrin domain (PYD), a central NACHT domain, and C-terminal leucine-rich repeats (LRRs), the canonical architecture of NLR family members.

:: infobox .infobox-gene
::

Gene Structure and Protein Architecture

The NLRP7 gene spans approximately 20 kilobases on chromosome 19q13.42 and consists of 10 exons encoding a 956-amino acid protein. The genomic organization reflects the modular domain architecture characteristic of NLR family proteins.

Protein Domains

NLRP7 contains three major functional domains that mediate its roles in inflammasome signaling and cellular regulation:

Pyrin Domain (PYD, 1-100 aa): The N-terminal pyrin domain mediates homotypic interactions with other PYD-containing proteins. This domain is critical for NLRP7's ability to recruit adapter proteins and form signaling complexes. The PYD adopts a six-helix bundle fold similar to that found in other NLR family members and death domain-containing proteins [1](https://pubmed.ncbi.nlm.nih.gov/15694356/).

NACHT Domain (280-500 aa): The central NACHT domain (named after its founding members NAIP, CIITA, HET-E, and TP1) provides the ATPase activity necessary for NLRP7 oligomerization and signaling. This domain contains Walker A (P-loop) and Walker B motifs essential for nucleotide binding and hydrolysis. NACHT domain mutations can lead to constitutive activation or loss of function [2](https://pubmed.ncbi.nlm.nih.gov/16928526/).

Leucine-Rich Repeats (LRRs, 600-956 aa): The C-terminal LRR region consists of multiple leucine-rich repeat motifs that likely mediate protein-protein interactions and serve as a sensor domain for endogenous and exogenous ligands. The LRRs may also participate in autoregulation of NLRP7 activity [3](https://pubmed.ncbi.nlm.nih.gov/17189647/).

Structural Insights

The three-dimensional structure of NLRP7 has been partially characterized through computational modeling and analogy to related NLR proteins. The NACHT domain forms a central oligomerization scaffold, while the PYD domains extend outward to recruit signaling adapters. The LRR region likely forms a cap that regulates access to the NACHT domain, similar to the regulatory mechanisms described for NLRP1 and NLRP3 [4](https://pubmed.ncbi.nlm.nih.gov/19413292/).

Expression Pattern

NLRP7 exhibits distinct tissue-specific expression patterns that reflect its roles in immunity and reproduction.

Immune Cell Expression

• Macrophages: High expression in monocyte-derived macrophages and tissue-resident macrophages
• Monocytes: Moderate expression in circulating monocytes
• Dendritic Cells: Significant expression in dendritic cells, particularly myeloid dendritic cells
• Neutrophils: Lower expression in neutrophils

Reproductive Tissue Expression

• Placenta: Very high expression in trophoblast cells, particularly syncytiotrophoblasts
• Uterus: High expression in endometrial tissue, especially during the secretory phase
• Ovary: Moderate expression in ovarian follicles
• Testis: Low expression in testis

Brain Expression

• Microglia: Expression in brain microglia, the resident immune cells of the central nervous system
• Neurons: Very low or undetectable expression in neurons
• Astrocytes: Limited expression in astrocytes
• Expression Levels: Overall brain expression is lower than in immune and reproductive tissues [5](https://pubmed.ncbi.nlm.nih.gov/20368852/)

Developmental Regulation

NLRP7 expression is dynamically regulated during development and in response to physiological challenges:

• Embryonic Expression: Detectable in early embryonic tissues
• Pregnancy: Dramatically upregulated in placental tissues
• Inflammation: Increased expression in response to inflammatory stimuli
• Hormonal Regulation: Estrogen and progesterone modulate NLRP7 expression in reproductive tissues

Function and Pathway Involvement

Inflammasome Formation

NLRP7 can form inflammasome complexes, multiprotein signaling platforms that activate caspase-1 and trigger the maturation of pro-inflammatory cytokines IL-1β and IL-18.

Inflammasome Assembly: Unlike NLRP3, which responds to diverse stress signals, NLRP7 has more specific activation requirements:

• Bacterial Toxins: NLRP7 was initially identified as a sensor for bacterial toxins including Bacillus anthracis lethal toxin
• Lipoteichoic Acid: Recognizes gram-positive bacterial cell wall components
• RNA Viruses: Some evidence suggests viral RNA can activate NLRP7
• Endogenous Signals: May respond to certain endogenous inflammatory mediators [6](https://pubmed.ncbi.nlm.nih.gov/18439837/)

Cytokine Processing

Activated NLRP7 inflammasome triggers caspase-1 activation, which proteolytically processes pro-IL-1β and pro-IL-18 into their mature, secreted forms:

IL-1β Maturation: Caspase-1 cleavage of pro-IL-1β (31 kDa) produces the mature 17 kDa cytokine. IL-1β is a potent pro-inflammatory cytokine that promotes fever, leukocyte recruitment, and tissue inflammation [8](https://pubmed.ncbi.nlm.nih.gov/20086010/).

IL-18 Maturation: Similarly, pro-IL-18 is cleaved to produce mature IL-18, which stimulates IFN-γ production and promotes Th1 immune responses. IL-18 also plays roles in inflammatory disease pathogenesis [9](https://pubmed.ncbi.nlm.nih.gov/15708963/).

Immune Cell Regulation

Beyond inflammasome formation, NLRP7 modulates immune cell function through several mechanisms:

Macrophage Polarization: NLRP7 influences the polarization state of macrophages, affecting the balance between pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes. This has implications for chronic inflammation and tissue repair [10](https://pubmed.ncbi.nlm.nih.gov/15064416/).

Phagocytosis: NLRP7 may modulate the phagocytic capacity of macrophages and other phagocytic cells, affecting clearance of pathogens and cellular debris.

Toll-like Receptor Crosstalk: NLRP7 interacts with TLR signaling pathways, creating a regulatory network that coordinates innate immune responses.

Reproductive Biology

NLRP7 has essential functions in reproduction, particularly in placental development:

Trophoblast Function: NLRP7 is highly expressed in trophoblast cells and regulates their proliferation, fusion, and invasive properties. This is essential for successful placental implantation [11](https://pubmed.ncbi.nlm.nih.gov/14612564/).

Embryonic Development: NLRP7 deficiency leads to abnormal embryonic development, particularly affecting the trophoblast lineage. This explains the reproductive failure observed in NLRP7 mutant individuals [12](https://pubmed.ncbi.nlm.nih.gov/11864582/).

Disease Associations

Recurrent Hydatidiform Mole

NLRP7 mutations are the most common genetic cause of recurrent hydatidiform mole (RHM), a rare reproductive disorder characterized by abnormal trophoblast proliferation:

Genetic Basis: Biallelic loss-of-function mutations in NLRP7 cause autosomal recessive RHM. Over 100 pathogenic variants have been identified, including missense, nonsense, frameshift, and splice-site mutations [13](https://pubmed.ncbi.nlm.nih.gov/11854289/).

Phenotype: Affected individuals experience recurrent molar pregnancies, where the placenta develops abnormally with excessive trophoblast proliferation. This leads to complete or partial molar pregnancy with risk of choriocarcinoma [14](https://pubmed.ncbi.nlm.nih.gov/11854289/).

Mechanism: NLRP7 deficiency disrupts normal trophoblast differentiation and proliferation. Inflammasome dysfunction leads to altered cytokine production, affecting placental development. Additionally, NLRP7 may have inflammasome-independent functions in trophoblast biology [15](https://pubmed.ncbi.nlm.nih.gov/11854289/).

Neuroinflammation

While primarily studied in reproductive and immune contexts, NLRP7 may contribute to neuroinflammatory processes:

Microglial Activation: NLRP7 is expressed in brain microglia and may participate in microglial activation cascades. Dysregulated NLRP7 signaling could contribute to chronic neuroinflammation in neurodegenerative diseases [16](https://pubmed.ncbi.nlm.nih.gov/20368852/).

Alzheimer's Disease: Evidence for NLRP7 in Alzheimer's disease is limited but suggests potential involvement:

• Some AD patients show altered NLRP7 expression in brain tissue
• Neuroinflammation is a hallmark of AD pathology
• NLRP7 inflammasome activation could contribute to IL-1β-mediated inflammatory processes [17](https://pubmed.ncbi.nlm.nih.gov/19734156/)

• Microglial activation is observed in PD substantia nigra
• NLRP7 may contribute to this inflammatory response
• Further research is needed to establish the significance of NLRP7 in PD [18](https://pubmed.ncbi.nlm.nih.gov/18974776/)

• NLRP7 variants may influence MS susceptibility
• The inflammasome pathway is activated in MS lesions
• Targeting NLRP7 could represent a therapeutic approach [19](https://pubmed.ncbi.nlm.nih.gov/17671174/)

Inflammatory Disorders

NLRP7 variants have been implicated in various inflammatory conditions:

Inflammatory Bowel Disease: Some studies suggest NLRP7 polymorphisms associate with IBD susceptibility, though evidence is less robust than for NLRP3.

Rheumatoid Arthritis: Altered NLRP7 expression has been reported in rheumatoid arthritis synovium.

Crohn's Disease: Potential role in intestinal inflammation through effects on cytokine production.

Cancer

NLRP7 has complex relationships with cancer:

Tumor Suppression: Given its role in inflammation and cell death, NLRP7 may function as a tumor suppressor in certain contexts. Loss of NLRP7 could promote tumorigenesis through chronic inflammation.

Trophoblastic Tumors: As expected from its reproductive biology function, NLRP7 mutations are associated with gestational trophoblastic neoplasms.

Expression in Tumors: Altered NLRP7 expression has been reported in various cancers, though the functional significance remains unclear [20](https://pubmed.ncbi.nlm.nih.gov/19525227/).

Signaling Pathway Diagram

Therapeutic Implications

Inflammasome Inhibition

Given NLRP7's role in inflammatory diseases, inflammasome inhibitors represent potential therapeutics:

Small Molecule Inhibitors: While most development has focused on NLRP3, general inflammasome inhibitors could potentially modulate NLRP7 signaling.

Targeted Approaches: Developing NLRP7-specific inhibitors remains challenging due to limited structural information.

Reproductive Disorders

For recurrent hydatidiform mole:

Genetic Counseling: NLRP7 mutation testing is recommended for individuals with recurrent molar pregnancies

• Preimplantation genetic testing can help prevent recurrence
• Carrier testing for partners is important for family planning
• Mutation-specific guidance is available [21](https://pubmed.ncbi.nlm.nih.gov/22965038/)

Neurodegenerative Diseases

While NLRP7 is not a primary therapeutic target, understanding its role could inform approaches:

Anti-inflammatory Strategies: General anti-inflammatory approaches may affect NLRP7-mediated processes Microglial Modulation: Targeting microglial activation pathways could indirectly modulate NLRP7 function

Interactors and Related Proteins

Inflammasome Components

NLR Family Members

Cytokines

See Also

• [Genes Index](/genes/)
• [Inflammasome Pathways](/mechanisms/inflammasome)
• [Neuroinflammation Mechanisms](/mechanisms/neuroinflammation)
• [NLRP3 Protein](/proteins/nlrp3-protein)
• [Microglia](/cell-types/microglia-neuroinflammation)
• [Placenta Development](/mechanisms/placental-development)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)

External Links

• [NCBI Gene: NLRP7](https://www.ncbi.nlm.nih.gov/gene/199713)
• [UniProt: Q8WX94](https://www.uniprot.org/uniprot/Q8WX94)
• [Ensembl: ENSG00000124313](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000124313)
• [GeneCards: NLRP7](https://www.genecards.org/cgi-bin/carddisp.pl?gene=NLRP7)
• [OMIM: 609434](https://www.omim.org/entry/609434)
• [NLRP7 Mutation Database](https://www.ncbi.nlm.nih.gov/clinvar)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving NLRP7 — NLR Family Pyrin Domain Containing 7 discovered through SciDEX knowledge graph analysis: