NLRP1

This gene encodes a member of the Ced-4 family of apoptosis proteins. Ced-family members contain a caspase recruitment domain (CARD) and are known to be key mediators of programmed cell death. The encoded protein contains a distinct N-terminal pyrin-like motif, which is possibly involved in protein-protein interactions. This protein interacts strongly with caspase 2 and weakly with caspase 9. Overexpression of this gene was demonstrated to induce apoptosis in cells. Multiple alternatively spliced transcript variants encoding distinct isoforms have been found for this gene, but the biological validity of some variants has not been determined.

NLR Family Pyrin Domain Containing 1

Acts as the sensor component of the NLRP1 inflammasome, which mediates inflammasome activation in response to various pathogen-associated signals, leading to subsequent pyroptosis (PubMed:22665479, PubMed:12191486, PubMed:17349957, PubMed:27662089, PubMed:31484767, PubMed:33093214, PubMed:33731929, PubMed:33731932).
Inflammasomes are supramolecular complexes that assemble in the cytosol in response to pathogens and other damage-associated signals and play critical roles in innate immunity and inflammation (PubMed:22665479, PubMed:12191486, PubMed:17349957).
Acts as a recognition receptor (PRR): recognizes specific pathogens and other damage-associated signals, such as cleavage by human rhinoviruses 14 and 16 (HRV-14 and HRV-16), double-stranded RNA or Val-boroPro inhibitor, and mediates the formation of the inflammasome polymeric complex composed of NLRP1, CASP1 and PYCARD/ASC (PubMed:22665479, PubMed:12191486, PubMed:17349957, PubMed:30291141, PubMed:33243852, PubMed:33093214).
In response to pathogen-associated signals, the N-terminal part of NLRP1 is degraded by the proteasome, releasing the cleaved C-terminal part of the protein (NACHT, LRR and PYD domains-containing protein 1, C-terminus), which polymerizes and associates with PYCARD/ASC to initiate the formation of the inflammasome complex: the NLRP1 inflammasome recruits pro-caspase-1 (proCASP1) and promotes caspase-1 (CASP1) activation, which subsequently cleaves and activates inflammatory cytokines IL1B and IL18 and gasdermin-D (GSDMD), leading to pyroptosis (PubMed:22665479, PubMed:12191486, PubMed:17349957, PubMed:32051255, PubMed:33093214).
Activation of NLRP1 inflammasome is also required for HMGB1 secretion; the active cytokines and HMGB1 stimulate inflammatory responses (PubMed:22801494).
Binds ATP and shows ATPase activity (PubMed:11113115, PubMed:15212762, PubMed:33243852).
Plays an important role in antiviral immunity and inflammation in the human airway epithelium (PubMed:33093214).
Specifically recognizes a number of pathogen-associated signals: upon infection by human rhinoviruses 14 and 16 (HRV-14 and HRV-16), NLRP1 is cleaved and activated which triggers NLRP1-dependent inflammasome activation and IL18 secretion (PubMed:33093214).
Positive-strand RNA viruses such as. Semliki forest virus and long dsRNA activate the NLRP1 inflammasome, triggering IL1B release in a NLRP1-dependent fashion (PubMed:33243852).
Acts as a direct sensor for long dsRNA and thus RNA virus infection (PubMed:33243852).
May also be activated by muramyl dipeptide (MDP), a fragment of bacterial peptidoglycan, in a NOD2-dependent manner (PubMed:18511561).
NACHT, LRR and PYD domains-containing protein 1
Constitutes the precursor of the NLRP1 inflammasome, which mediates autoproteolytic processing within the FIIND domain to generate the N-terminal and C-terminal parts, which are associated non-covalently in absence of pathogens and other damage-associated signals.
NACHT, LRR and PYD domains-containing protein 1, N-terminus
Regulatory part that prevents formation of the NLRP1 inflammasome: in absence of pathogens and other damage-associated signals, interacts with the C-terminal part of NLRP1 (NACHT, LRR and PYD domains-containing protein 1, C-terminus), preventing activation of the NLRP1 inflammasome (PubMed:33093214).
In response to pathogen-associated signals, this part is ubiquitinated and degraded by the proteasome, releasing the cleaved C-terminal part of the protein, which polymerizes and forms the NLRP1 inflammasome (PubMed:33093214).
NACHT, LRR and PYD domains-containing protein 1, C-terminus
Constitutes the active part of the NLRP1 inflammasome (PubMed:33093214, PubMed:33731929, PubMed:33731932).
In absence of pathogens and other damage-associated signals, interacts with the N-terminal part of NLRP1 (NACHT, LRR and PYD domains-containing protein 1, N-terminus), preventing activation of the NLRP1 inflammasome (PubMed:33093214).
In response to pathogen-associated signals, the N-terminal part of NLRP1 is degraded by the proteasome, releasing this form, which polymerizes and associates with PYCARD/ASC to form of the NLRP1 inflammasome complex: the NLRP1 inflammasome complex then directly recruits pro-caspase-1 (proCASP1) and promotes caspase-1 (CASP1) activation, leading to gasdermin-D (GSDMD) cleavage and subsequent pyroptosis (PubMed:33093214).
Isoform 2
It is unclear whether is involved in inflammasome formation. It is not cleaved within the FIIND domain, does not assemble into specks, nor promote IL1B release (PubMed:22665479).
However, in an vitro cell-free system, it has been shown to be activated by MDP (PubMed:17349957).

Activation of cysteine-type endopeptidase activity involved in apoptotic processManual Assertion Based On ExperimentIDA:HGNC-UCL
Antiviral innate immune responseManual Assertion Based On ExperimentIDA:UniProtKB
Aapoptotic process1 PublicationNAS:UniProtKB
Defense response to bacteriumISS:BHF-UCL
Defense response to virusManual Assertion Based On ExperimentIDA:UniProtKB
Inflammatory responseIEA:UniProtKB-KW
Neuron apoptotic processManual Assertion Based On ExperimentIDA:HGNC-UCL
NLRP1 inflammasome complex assemblyManual Assertion Based On ExperimentIMP:UniProtKB
Pattern recognition receptor signaling pathway1 PublicationIC:ComplexPortal
Positive regulation of inflammatory responseManual Assertion Based On ExperimentIDA:ComplexPortal
Positive regulation of interleukin-1 beta productionManual Assertion Based On ExperimentIDA:UniProtKB
Protein homooligomerizationManual Assertion Based On ExperimentIDA:UniProtKB
PyroptosisManual Assertion Based On ExperimentIDA:UniProtKB
Regulation of apoptotic processIEA:InterPro
Regulation of inflammatory response1 PublicationIC:BHF-UCL
Response to muramyl dipeptideISS:BHF-UCL
Self proteolysisManual Assertion Based On ExperimentIDA:UniProtKB

Cytoplasm, cytosol
Cytoplasm
Nucleus
Nucleocytoplasmic distribution in lymphoid organs (probably in T-cells) and in neurons. In epithelial cells, predominantly cytoplasmic.
NACHT, LRR and PYD domains-containing protein 1, C-terminus
Inflammasome

Vitiligo-associated multiple autoimmune disease 1 (VAMAS1):
A disorder characterized by the association of vitiligo with several autoimmune and autoinflammatory diseases including autoimmune thyroid disease, rheumatoid arthritis and systemic lupus erythematosus.
Palmoplantar carcinoma, multiple self-healing (MSPC):
An autosomal dominant disease characterized by keratopathy with neovascularization, bilateral corneal opacification, palmoplantar hyperkeratosis, dyshidrosis, dystrophic nails, and recurrent keratoacanthomas in palmoplantar skin as well as in conjunctival and corneal epithelia. In addition, patients experience a high susceptibility to malignant squamous cell carcinoma.
Autoinflammation with arthritis and dyskeratosis (AIADK):
A disorder characterized by recurrent fever, diffuse skin dyskeratosis, autoinflammation, autoimmunity, arthritis and high transitional B-cell level. Inheritance can be autosomal dominant or autosomal recessive.
Respiratory papillomatosis, juvenile recurrent, congenital (JRRP):
An autosomal recessive disease characterized by recurrent growth of papillomas in the respiratory tract, and onset in early childhood. Papillomas are most commonly found in the larynx but may occur anywhere from the mouth to the bronchi. Children typically present within the first years of life with hoarseness or, in more severe cases, respiratory distress or stridor and airway obstruction. JRRP is associated with infection of the upper airway by human papillomaviruses of the alpha genus. The infection is thought to occur by vertical transmission at birth.

NACHT, LRR and PYD domains-containing protein 1
Autocatalytically cleaved (PubMed:22087307, PubMed:22665479, PubMed:33093214).
Autocatalytic cleavage in FIIND region occurs constitutively, prior to activation signals, and is required for inflammasome activity (IL1B release), possibly by facilitating CASP1 binding (PubMed:22087307, PubMed:22665479, PubMed:33093214).
Both N- and C-terminal parts remain associated non-covalently (PubMed:22087307, PubMed:22665479, PubMed:33093214).
NACHT, LRR and PYD domains-containing protein 1, N-terminus
Ubiquitinated by the cullin:ZER1/ZYG11B complex in response to pathogen-associated signals, leading to its degradation by the proteasome and subsequent release of the cleaved C-terminal part of the protein (NACHT, LRR and PYD domains-containing protein 1, C-terminus), which polymerizes and forms the NLRP1 inflammasome.
(Microbial infection) Cleaved between Gln-130 and Gly-131 by human rhinovirus 14 (HRV-14) Protease 3C. This cleavage triggers N-glycine-mediated proteasomal degradation of the autoinhibitory NLRP1 N-terminal fragment via the cullin:ZER1/ZYG11B complex which liberates the activating C-terminal fragment and activates NLRP1 inflammasome.