Open AccessOverexpression of Phosphatidylinositol Synthase Enhances Growth and G1 Progression in NIH3T3 cells
Author(s) -
Deguchi Atsuko,
Segawa Kaoru,
Hosaka Kohei,
Weinstein I. Bernard,
Umezawa Kazuo
Publication year - 2002
Publication title -
japanese journal of cancer research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.035
H-Index - 141
eISSN - 1349-7006
pISSN - 0910-5050
DOI - 10.1111/j.1349-7006.2002.tb01254.x
Subject(s) - phosphatidylinositol , atp synthase , cell growth , microbiology and biotechnology , biology , chemistry , cancer research , enzyme , signal transduction , biochemistry
Phosphatidylinositol (PI) turnover is thought to play an important role in the regulation of cell growth. PI synthase (PIS, cytidine diphosphate (CDP)‐diacylglycerol (DG): myo ‐inositol 3–phos–phatidyltransferase, EC 2.7.8.11) acts at the last step in the de novo biosynthesis of PI by catalyzing the condensation of CDP‐DG and myo ‐inositol. To study the physiological role of PIS, we established murine NIH3T3 fibroblasts that stably overexpress PIS, by transfection with PIS cDNA (NIH‐PIS cells). In immunofluorescence assays, the constitutively overexpressed PIS was found to be localized in the endoplasmic reticulum, as previously reported for the native enzyme activity. NIH‐PIS cells showed an increase in PI synthesis in vitro and in vivo , as well as increased cellular levels of PI–4,5–P 2 and PI–3,4,5–P 3 . They also displayed a decrease in their doubling tune and accelerated G1 progression. Overexpression of PIS increased cellular levels of the cyclin D1 and E proteins and Akt kinase activity in serum‐stimulated quiescent NIH3T3 cells. Moreover, PIS Overexpression potentiated the colony formation of NIH3T3 cells in soft agar. These results suggest that PIS accelerates G1 progression and stimulates growth by increasing cellular levels of cyclins D1 and E.