An ENU-induced mouse mutant of SHIP1 reveals a critical role of the stem cell isoform for suppression of macrophage activation

Nhu-Y. N. Nguyen, Mhairi J. Maxwell, Lisa Ooms, Elizabeth M. Davies, Adrienne A. Hilton, Janelle E. Collinge, Douglas J. Hilton, Benjamin T. Kile, Christina A. Mitchell, Margaret L. Hibbs, Stephen M. Jane, David J. Curtis

Research output: Contribution to journalArticleResearchpeer-review

14 Citations (Scopus)

Abstract

In a recessive ENU mutagenesis screen for embryonic lethality, we identified a mouse pedigree with a missense mutation of SHIP1 (SHIP1el20) leading to an amino acid substitution I641T in the inositol-5′-phosphatase domain that represses phosphatidylinositol-3-kinase signaling. Despite detectable expression of functional SHIP1 protein, the phenotype of homozygous SHIP1el20/el20 mice was more severe than gene-targeted SHIP1-null (SHIP1−/−) mice. Compared with age-matched SHIP1−/− mice, 5-week-old SHIP1el20/el20 mice had increased myeloid cells, serum IL-6 levels, marked reductions in lymphoid cells, and died by 7 weeks of age with infiltration of the lungs by activated macrophages. Bone marrow transplantation demonstrated that these defects were hematopoietic-cell-autonomous. We show that the el20 mutation reduces expression in SHIP1el20/el20 macrophages of both SHIP1 and s-SHIP, an isoform of SHIP1 generated by an internal promoter. In contrast, SHIP1−/− macrophages express normal levels of s-SHIP. Compound heterozygous mice (SHIP1−/el20) had the same phenotype as SHIP1−/− mice, thus providing genetic proof that the more severe phenotype of SHIP1el20/el20 mice is probably the result of concomitant loss of SHIP1 and s-SHIP. Our results suggest that s-SHIP synergizes with SHIP1 for suppression of macrophage activation, thus providing the first evidence for a role of s-SHIP in adult hematopoiesis.
Original languageEnglish
Article number20
Pages (from-to)5362-5371
Number of pages10
JournalBlood
Volume117
Issue number20
DOIs
Publication statusPublished - 2011

Cite this