Determinants of phosphatidylinositol-4-phosphate 5-kinase type I?90 uropod location in T-lymphocytes and its role in uropod formation.

ABSTRACT: We have previously identified phosphatidylinositol-4-phosphate 5-kinase type I (PIPKI)?90 as a T cell uropod component. However, the molecular determinants and functional consequences of its localization remain unknown. In this report, we seek to better understand the mechanisms involved in PIPKI?90 uropod targeting and the role that PIPKI?90 plays in T cell uropod formation. During T cell activation, PIPKI?90 cocaps with the membrane microdomain-associated proteins flotillin-1 and -2 and accumulates in the uropod. We report that the C-terminal 26 amino acid extension of PIPKI?90 is required for its localization to the uropod. We further use T cells from PIPKI?90(-/-) mice and human T cells expressing a kinase-dead PIPKI?90 mutant to examine the role of PIPKI?90 in a T cell uropod formation. We find that PIPKI?90 deficient T cells have elongated uropods on ICAM-1. Moreover, in human T cells overexpression of PIPKI?87, a naturally occurring isoform lacking the last 26 amino acids, suppresses uropod formation and impairs capping of uropod proteins such as flotillins. Transfection of human T cells with a dominant-negative mutant of flotillin-2 in turn attenuates capping of PIPKI?90. Our data contribute to the understanding of the molecular mechanisms that regulate T cell uropod formation.

SUBMITTER: Mathis L 

PROVIDER: S-EPMC3757496 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature