Nlrp9

NLRPs (acronym for "NIGHT, LRR and PYD domains-containing protein) are, together with the NOD1 and NOD2 proteins, members of the NLR (Nod-like Receptor) protein family and play a major role in innate immunity as pathogen recognition receptors (PPRs). Like the NOD proteins, NLRPs are expressed exclusively cytoplasmically. All NLRPs (they all contain a pyrin domain) are encoded by a common gene family in humans. NLRPs are characterised by their ability to activate different inflammatory complexes.

NLRP9 is a cytosolic protein encoded in humans by the NLRP8 gene located on chromosome 19 q13.42 (location 19: 55.71 - 55.74 Mb) within a cluster of other NLRP genes.

Inflammasomes are differently composed cytosolic protein complexes, whereby the different NLRPs are of great importance for their functionality. Inflammasomes are predominantly found in immune cells such as dendritic cells and macrophages.

The activation of an inflammasome complex leads to the expression of different caspases, which convert inactive interleukin-1beta and interleukin-18 into their active form.

Little is known about the mode of action of NLRP9. NLRP8 and NLRP9 are mainly expressed in tests, ovaries and oocytes.

In Helicobacter pylori infected gastric cancer cells, several pathogen recognition receptors such as NLRP9 and NLRP12 as well as NLRC4, NLRC5 and NLRX1 are upregulated in response to infection. This observation is accompanied by a down-regulation of NLRP12 and NLRX1.

1. Castaño-Rodríguez N et al (2014) The NOD-like receptor signalling pathway in Helicobacter pylori infection and related gastric cancer: a case-control study and gene expression analyses. PLoS One 9:e98899.
2. Chu JQ et al (2016) Production of IL-1β and Inflammasome with Up-Regulated Expressions of NOD-Like Receptor Related Genes in Toxoplasma gondii-Infected THP-1 Macrophages. Korean J Parasitol 54(:711-717.
3. Ponsuksili S et al (2006) Bovine NALP5, NALP8, and NALP9 genes: assignment to a QTL region and the expression in adult tissues, oocytes, and preimplantation embryos. Biol Reprod 74:577-584.