NLRP12 binds to Hck potentially regulating the NF‐kB pathway

Abstract

The nod‐like receptor family pyrin domain containing 12 (Nlrp12) is a cytoplasmic protein that belongs to the Pattern Recognition Receptor family (PRR) of proteins, an important component of the innate immune system for identification of Pattern Associated Molecular Patterns (PAMPs) and Damage‐Associated Molecular Patterns (DAMPs). Nlrp12 is comprised of 1062 amino acids and has three functional domains: an N‐terminal pyrin domain, a Nucleotide‐ Binding Domain (NBD), and a C‐terminal leucine‐rich repeat region. Nlrp12 is mainly expressed in peripheral blood leukocytes, including granulocytes, eosinophils, monocytes, and dendritic cells. Nlrp12 has been shown to function as a negative regulator of inflammation through canonical and non‐canonical NF‐kB pathways. However, the detailed mechanism of how Nlrp12 inhibits NF‐kB is not clear.The Nlrp12 pyrin and NBD domain was used as bait in a yeast two‐hybrid screen for potential interacting partners in a human leukocyte cDNA library. The top hit was the C‐terminal fragment of Hck; it was shown to interact strongly with Nlrp12. Detailed mapping of the binding between Nlrp12 and Hck was performed. In subsequent yeast two‐hybrid assays, Nlrp12 was shown specifically to bind to Hck. The C‐terminal 30 amino acids of Hck was sufficient to bind with Nlrp12. This fragment carries the negative regulatory phosphotyrosine residue Y521. However, the binding did not require phosphorylation of Y521 residue of Hck. That is, Nlrp12 preferentially bound to unphosphorylated Hck (i.e., active Hck). Functional NF‐KB luciferase reporter assays were performed with 293T cells overexpressing either Nlrp12, or Hck, or Nlrp12 plus Hck. Overexpression of Nlrp12 alone decreased NF‐kB activity, while overexpression of Hck rescued the inhibition of NF‐kB activity by overexpressed Nlrp12. Overexpression of Hck alone had no effect on NF‐kB activity.We conclude that Hck may be a novel regulator of Nlrp12 activity in its inhibition of NF‐kB function.Support or Funding InformationUniversity of Southern California School of Pharmacy Intramural Research Funds 2017‐ 2021This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.