NLRC4

{{Short description|Protein-coding gene in the species Homo sapiens}}

NLR family CARD domain-containing protein 4 is a protein that in humans is encoded by the NLRC4 gene.{{cite journal | vauthors = Geddes BJ, Wang L, Huang WJ, Lavellee M, Manji GA, Brown M, Jurman M, Cao J, Morgenstern J, Merriam S, Glucksmann MA, DiStefano PS, Bertin J | title = Human CARD12 is a novel CED4/Apaf-1 family member that induces apoptosis | journal = Biochemical and Biophysical Research Communications | volume = 284 | issue = 1 | pages = 77–82 | date = Jun 2001 | pmid = 11374873 | doi = 10.1006/bbrc.2001.4928 }}{{cite web | title = Entrez Gene: NLRC4 NLR family, CARD domain containing 4| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=58484}}

Structure

The NLRC4 protein is highly conserved across mammalian species. It bears homology to the C. elegans Ced4 protein. It contains an N-terminal CARD domain, a central nucleotide binding/NACHT domain, and a C-terminal leucine rich repeat (LRR) domain. It belongs to a family of NLR proteins that includes the transcriptional co-activator CIITA and the canonical inflammasome protein NLRP3. A truncated murine NLRC4 was the first member of this family whose crystal structure was solved.{{cite journal | vauthors = Hu Z, Yan C, Liu P, Huang Z, Ma R, Zhang C, Wang R, Zhang Y, Martinon F, Miao D, Deng H, Wang J, Chang J, Chai J | title = Crystal structure of NLRC4 reveals its autoinhibition mechanism | journal = Science | volume = 341 | issue = 6142 | pages = 172–5 | date = Jul 2013 | pmid = 23765277 | doi = 10.1126/science.1236381 | bibcode = 2013Sci...341..172H | s2cid = 12360722 | doi-access = free }}

Function

NLRC4 is best associated with triggering formation of the inflammasome. Unlike NLRP3, certain inflammasome-dependent functions of NLRC4 may be carried out independently of the inflammasome scaffold ASC. Human Ced4 homologs include APAF1, NOD1 (CARD4), and NOD2 (CARD15). These proteins have at least 1 N-terminal CARD domain followed by a centrally located nucleotide-binding domain (NBD or NACHT) and a C-terminal regulatory domain, found only in mammals, that contains either WD40 repeats or leucine-rich repeats (LRRs). CARD12 is a member of the Ced4 family and can induce apoptosis.

Interactions

NLRC4 has been shown to interact with NAIP (there is one human NAIP but mice express at least 4 distinct NAIP proteins). The NAIP/NLRC4 interaction may determine the ligand specificity.{{cite journal | vauthors = Kofoed EM, Vance RE | title = Innate immune recognition of bacterial ligands by NAIPs determines inflammasome specificity | journal = Nature | volume = 477 | issue = 7366 | pages = 592–5 | date = Sep 2011 | pmid = 21874021 | pmc = 3184209 | doi = 10.1038/nature10394 | bibcode = 2011Natur.477..592K }} NLRC4-dependent inflammasome activity activates CASP1.{{cite journal | vauthors = Damiano JS, Oliveira V, Welsh K, Reed JC | title = Heterotypic interactions among NACHT domains: implications for regulation of innate immune responses | journal = The Biochemical Journal | volume = 381 | issue = Pt 1 | pages = 213–9 | date = Jul 2004 | pmid = 15107016 | pmc = 1133779 | doi = 10.1042/BJ20031506 }} Under certain circumstances, NLRC4 and NLRP3 may occupy the same inflammasome complex.{{cite journal | vauthors = Man SM, Hopkins LJ, Nugent E, Cox S, Glück IM, Tourlomousis P, Wright JA, Cicuta P, Monie TP, Bryant CE | title = Inflammasome activation causes dual recruitment of NLRC4 and NLRP3 to the same macromolecular complex | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 111 | issue = 20 | pages = 7403–8 | date = May 2014 | pmid = 24803432 | pmc = 4034195 | doi = 10.1073/pnas.1402911111 | bibcode = 2014PNAS..111.7403M | url = https://www.repository.cam.ac.uk/bitstream/1810/245267/1/Accepted%20ms%20PNAS%202014%20Man%20et%20al%20%281%29.pdf | doi-access = free }}

Clinical significance

Humans bearing activating mutations in NLRC4 can develop an autoinflammatory syndrome characterized by acute fever, hepatitis, very high serum ferritin, and other features suggestive of Macrophage Activation Syndrome (MAS). Some patients also developed a potentially life-threatening enterocolitis that abated during early childhood.{{cite journal | vauthors = Canna SW, de Jesus AA, Gouni S, Brooks SR, Marrero B, Liu Y, DiMattia MA, Zaal KJ, Sanchez GA, Kim H, Chapelle D, Plass N, Huang Y, Villarino AV, Biancotto A, Fleisher TA, Duncan JA, O'Shea JJ, Benseler S, Grom A, Deng Z, Laxer RM, Goldbach-Mansky R | title = An activating NLRC4 inflammasome mutation causes autoinflammation with recurrent macrophage activation syndrome | journal = Nature Genetics | volume = 46 | issue = 10 | pages = 1140–6 | date = Oct 2014 | pmid = 25217959 | pmc = 4177369 | doi = 10.1038/ng.3089 }}{{cite journal | vauthors = Romberg N, Al Moussawi K, Nelson-Williams C, Stiegler AL, Loring E, Choi M, Overton J, Meffre E, Khokha MK, Huttner AJ, West B, Podoltsev NA, Boggon TJ, Kazmierczak BI, Lifton RP | title = Mutation of NLRC4 causes a syndrome of enterocolitis and autoinflammation | journal = Nature Genetics | volume = 46 | issue = 10 | pages = 1135–9 | date = Oct 2014 | pmid = 25217960 | pmc = 4177367 | doi = 10.1038/ng.3066 }} In these patients, chronic and extraordinary elevation of serum IL-18 is found, in distinction from patients with NLRP3 mutations who develop Cryopyrin Associated Periodic Syndromes. A large Japanese family had much milder disease associated with cold-induced urticaria that was caused by a dominantly inherited NLRC4 mutation.{{cite journal | vauthors = Kitamura A, Sasaki Y, Abe T, Kano H, Yasutomo K | title = An inherited mutation in NLRC4 causes autoinflammation in human and mice | journal = The Journal of Experimental Medicine | volume = 211 | issue = 12 | pages = 2385–96 | date = Nov 2014 | pmid = 25385754 | pmc = 4235634 | doi = 10.1084/jem.20141091 }}

NLRC4

Structure

Function

Interactions

Clinical significance

References

Further reading