Pellino‐2 in nonimmune cells: novel interaction partners and intracellular localization

Abstract

Pellino‐2 is an E3 ubiquitin ligase that mediates intracellular signaling in innate immune pathways. Most studies of endogenous Pellino‐2 have been performed in macrophages, but none in nonimmune cells. Using yeast two‐hybrid screening and co‐immunoprecipitation, we identified six novel interaction partners of Pellino‐2, with various localizations: insulin receptor substrate 1, NIMA‐related kinase 9, tumor necrosis factor receptor‐associated factor 7, cyclin‐F, roundabout homolog 1, and disheveled homolog 2. Pellino‐2 showed cytoplasmic localization in a wide range of nonimmune cells under physiological potassium concentrations. Treatment with the potassium ionophore nigericin resulted in nuclear localization of Pellino‐2, which was reversed by the potassium channel blocker tetraethylammonium. Live‐cell imaging revealed intracellular migration of GFP‐tagged Pellino‐2. In summary, Pellino‐2 interacts with proteins at different cellular locations, taking part in dynamic processes that change its intracellular localization influenced by potassium efflux.

The Emerging Roles of Pellino Family in Pattern Recognition Receptor Signaling

“…Only a few proteins have been reported to mediate the Pellino1, e.g., Smad6/7 (20,21), DEAF1 (88), Bid (89), and DAPK1 (98), which positively or negatively regulate the Pellino family. A new study reports six novel interaction partners of Pellino-2 in the liver cells, insulin receptor substrate 1 (IRS-1), NIMA-related kinase 9 (NEK9), tumor necrosis factor receptor-associated factor 7 (TRAF7), roundabout homolog 1 (ROBO-1), and disheveled homolog 2 (DVL-2) (141). More efforts are needed to study the expression and binding partners of the Pellino family in both the immune cells and non-immune cells.…”

A Pellino‐2 variant is associated with constitutive NLRP3 inflammasome activation in a family with ocular pterygium–digital keloid dysplasia

“…Exchange from a polar threonine to a nonpolar isoleucine will probably disrupt at least some of these interactions. In addition, Pellino‐2 is known to interact with TAK1 [16–18]. Mutations in MAP3K7 , encoding TAK1, and its associated binding protein TAB2 have been linked to keloid scar formation [19], leading us to conclude that PELI2 was the most likely gene associated with the OPDKD phenotype in our patient.…”

“…Pellino‐2 seems to relocate intracellularly upon efflux of K + ions: in immune cells, Pellino‐2 relocates to the site of the NLRP3 inflammasome activation, following K + efflux [12]. In nonimmune cells, K + efflux leads to the nuclear relocation of Pellino‐2 [16].…”

“…We have recently shown that Pellino‐2 interacts with several proteins involved in various intracellular pathways and with different intracellular localizations. In addition to the classical toll‐like receptor (TLR) pathway proteins, such as IRAK‐1, TAK1, and TRAF6, Pellino‐2 also binds to ROBO‐1, NEK9, DVL‐2, cyclin F, and TRAF7, as well as IRS‐1 [16]. We therefore investigated if the Thr257Ile Pellino‐2 substitution influences the binding of Pellino‐2 to its interaction partners.…”

“…Nontransduced and transduced HEK293 cells were seeded in 10‐cm dishes and cultured until 70–80 % confluency. For TRAF7 detection, the HEK293 cells were transiently transfected as previously described [16], with the TRAF7‐myc expression vector, described above.…”