A pleckstrin homology-related domain in SHIP1 mediates membrane localization during Fc gamma receptor-induced phagocytosis

作者：Ming Lum Andrew; Shojania Shaheen; So Eva; McCarrell Erin; Shaw Eileen; Vu David; Wang Ida; McIntosh Lawrence P; Mui Alice L F^*

来源：The FASEB Journal, 2012, 26(8): 3163-3177.

DOI：10.1096/fj.11-201475

• phosphoinositide-3 ' kinase
• macrophage
• lipid-binding domain

SH2 domain-containing inositol-5'-phosphatase-1 (SHIP1) inhibits inflammation by hydrolyzing phosphoinositide-3'-kinase generated membrane phosphatidylinositol-3,4,5-trisphosphate (PIP3). Bioinformatic analysis of SHIP1 from multiple species revealed a pleckstrin homololgy-related (PH-R) domain, which we hypothesize mediates SHIP1's association with the membrane, a requirement for its biological function. Recombinant murine SHIP1 PH-R domain was subjected to biophysical and biochemical analysis. Residues K370 and K397 were found to be important for PH-R domain association with membrane PIP3. Wildtype PH-R domain bound PIP3 with 1.9 +/- 0.2 nM affinity, while the affinity of a K370A/K397A substituted mutant was too low to measure. Wild-type ( but not the K370A/K397A substituted) full-length SHIP1 protein, reconstitutes normal inhibition of Fc gamma receptor-mediated phagocytosis when introduced into SHIP1(-/-) murine macrophages, reducing the number of phagocytic events by 2-fold as compared to SHIP1(-/-) cells. In fact, the PH-R-mediated membrane interaction appears to be a major mechanism by which SHIP1 is recruited to the membrane, since the K370A/K397A substitution reduced the recruitment of both full-length SHIP1 and the PH-R domain by >= 2-fold. We have previously shown that SHIP1 enzyme activity can be targeted for therapeutic purposes. The current studies suggest that molecules targeting the PH-R domain can also modulate SHIP1 function.-Ming-Lum, A., Shojania, S., So, E., McCarrell, E., Shaw, E., Vu, D., Wang, I., McIntosh, L. P., Mui, A. L. F. A pleckstrin homology-related domain in SHIP1 mediates membrane localization during Fc gamma receptor-induced phagocytosis. FASEB J. 26, 3163-3177 (2012). www.fasebj.org

• 出版日期2012-8