TY - JOUR
T1 - Evidence that SHIP-1 contributes to phosphatidylinositol 3,4,5-trisphosphate metabolism in T lymphocytes and can regulate novel phosphoinositide 3-kinase effectors
AU - Freeburn, Robin W.
AU - Wright, Karen L.
AU - Burgess, Steven J.
AU - Astoul, Emmanuelle
AU - Cantrell, Doreen A.
AU - Ward, Stephen G.
PY - 2002/11/15
Y1 - 2002/11/15
N2 - The leukemic T cell line Jurkat is deficient in protein expression of the lipid phosphatases Src homology 2 domain containing inositol polyphosphate phosphatase (SHIP) and phosphatase and tensin homolog deleted on chromosome ten (PTEN). We examined whether the lack of expression of SHIP-1 and PTEN is shared by other leukemic T cell lines and PBLs. Analysis of a range of cell lines and PBLs revealed that unlike Jurkat cells, two other well-characterized T cell lines, namely CEM and MOLT-4 cells, expressed the 5′-phosphatase SHIP at the protein level. However, the 3-phosphatase PTEN was not expressed by CEM or MOLT-4 cells or Jurkat cells. The HUT78 cell line and PBLs expressed both SHIP and PTEN. Jurkat cells exhibited high basal levels of phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3; the lipid substrate for both SHIP and PTEN) as well as saturated protein kinase B (PKB) phosphorylation. Lower levels of PI(3,4,5)P3 and higher levels of phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2) as well as unsaturated constitutive phosphorylation of PKB were observed in CEM and MOLT-4 cells compared with Jurkat cells. In PBLs and HUT78 cells which express both PTEN and SHIP-1, there was no constitutive PI(3,4,5)P3 or PKB phosphorylation, and receptor stimuli were able to elicit robust phosphorylation of PKB. Expression of a constitutively active SHIP-1 protein in Jurkat cells was sufficient to reduce both constitutive PKB membrane localization and PKB phosphorylation. Together, these data indicate important differences between T leukemic cells as well as PBLs, regarding expression of key lipid phosphatases. This study provides the first evidence that SHIP-1 can influence the constitutive levels of PI(3,4,5)P3 and the activity of downstream phosphoinositide 3-kinase effectors in T lymphocytes.
AB - The leukemic T cell line Jurkat is deficient in protein expression of the lipid phosphatases Src homology 2 domain containing inositol polyphosphate phosphatase (SHIP) and phosphatase and tensin homolog deleted on chromosome ten (PTEN). We examined whether the lack of expression of SHIP-1 and PTEN is shared by other leukemic T cell lines and PBLs. Analysis of a range of cell lines and PBLs revealed that unlike Jurkat cells, two other well-characterized T cell lines, namely CEM and MOLT-4 cells, expressed the 5′-phosphatase SHIP at the protein level. However, the 3-phosphatase PTEN was not expressed by CEM or MOLT-4 cells or Jurkat cells. The HUT78 cell line and PBLs expressed both SHIP and PTEN. Jurkat cells exhibited high basal levels of phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3; the lipid substrate for both SHIP and PTEN) as well as saturated protein kinase B (PKB) phosphorylation. Lower levels of PI(3,4,5)P3 and higher levels of phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2) as well as unsaturated constitutive phosphorylation of PKB were observed in CEM and MOLT-4 cells compared with Jurkat cells. In PBLs and HUT78 cells which express both PTEN and SHIP-1, there was no constitutive PI(3,4,5)P3 or PKB phosphorylation, and receptor stimuli were able to elicit robust phosphorylation of PKB. Expression of a constitutively active SHIP-1 protein in Jurkat cells was sufficient to reduce both constitutive PKB membrane localization and PKB phosphorylation. Together, these data indicate important differences between T leukemic cells as well as PBLs, regarding expression of key lipid phosphatases. This study provides the first evidence that SHIP-1 can influence the constitutive levels of PI(3,4,5)P3 and the activity of downstream phosphoinositide 3-kinase effectors in T lymphocytes.
UR - http://www.scopus.com/inward/record.url?scp=0037111475&partnerID=8YFLogxK
U2 - 10.4049/jimmunol.169.10.5441
DO - 10.4049/jimmunol.169.10.5441
M3 - Article
C2 - 12421919
AN - SCOPUS:0037111475
SN - 0022-1767
VL - 169
SP - 5441
EP - 5450
JO - Journal of Immunology
JF - Journal of Immunology
IS - 10
ER -