Biomedical subjects

I Dominguez

Publications and source records attributed to I Dominguez.

29 records · Page 2Linked to original sources

PubMed1992

Evidence for a role of protein kinase C zeta subspecies in maturation of Xenopus laevis oocytes.

A number of studies have demonstrated the activation of phospholipase C-mediated hydrolysis of phosphatidylcholine (PC-PLC) both by growth factors and by the product of the ras oncogene, p21ras. Evidence has been presented indicating that the stimulation of this phospholipid degradative pathway is sufficient to activate mitogenesis in fibroblasts as well as that it is sufficient and necessary for induction of maturation in Xenopus laevis oocytes. However, the mechanism whereby PC-PLC transduces mitogenic signals triggered by growth factors or oncogenes remains to be elucidated. In this study, data are presented that show the involvement of protein kinase C zeta subspecies in the channelling of the mitogenic signal activated by insulin-p21ras-PC-PLC in Xenopus oocytes as well as the lack of a critical role of protein kinase C isotypes alpha, beta, gamma, delta, and epsilon in these pathways.

Amino Acid Sequence↗

PubMed1991

Requirement of phospholipase C-catalyzed hydrolysis of phosphatidylcholine for maturation of Xenopus laevis oocytes in response to insulin and ras p21.

Recent studies have demonstrated the activation of phospholipase C-mediated hydrolysis of phosphatidylcholine both by growth factors and by the product of ras oncogene, ras p21. Also, evidence has been presented indicating that the stimulation of this phospholipid-degradative pathway is sufficient to activate mitogenesis in fibroblasts. In Xenopus laevis oocytes, microinjection of transforming ras p21 is a potent inducer of maturation, whereas microinjection of a neutralizing anti-ras p21 antibody specifically inhibits maturation induced by insulin but not by progesterone. The results presented here demonstrated that microinjection of phosphatidylcholine-hydrolyzing phospholipase C is sufficient to induce maturation of Xenopus laevis oocytes. Furthermore, microinjection of a neutralizing anti-phosphatidylcholine-hydrolyzing phospholipase C specifically blocks the maturation program induced by ras p21/insulin but not by progesterone.

Animals↗

PubMed1991

Role of GTPase activating protein in mitogenic signalling through phosphatidylcholine-hydrolysing phospholipase C.

Recent evidence has accumulated showing that activation of PLC-catalysed hydrolysis of phosphatidylcholine (PC-PLC) is a critical step in mitogenic signal transduction both in fibroblasts and in oocytes from Xenopus laevis. The products of ras genes activate PC-PLC, bind guanine nucleotides, have intrinsic GTPase activity, and are regulated by a GTPase-activating protein (GAP). It has been suggested that, in addition to its regulatory properties, GAP may also be necessary for ras function as a downstream effector molecule. In this study, evidence is presented that strongly suggests that the functional interaction between ras p21 and GAP is sufficient and necessary for activation of maturation promoting factor (MPF) H1-kinase activity in oocytes, and that PC hydrolysis is critically involved in this mechanism. Therefore, we identify GAP as a further step required for signalling through PC-PLC, and necessary for the control of oocyte maturation in response to ras p21/insulin but not to progesterone.

Animals↗

PubMed1990

Adaptive response in human lymphocytes conditioned with hydrogen peroxide before irradiation with X-rays.

Cultured human lymphocytes were first exposed to a low 'conditioning' dose of hydrogen peroxide and, subsequently, irradiated with a 'challenge' dose of 1.5 Gy of X-rays in order to analyse the induction of an adaptive response to oxidative damage. A significant reduction in X-ray-induced chromosome damage was evident when H2O2 was given as a single 30 min pulse 24 h after setting up the cultures and the lymphocytes were exposed to X-rays at 48 h. In contrast, when the cells underwent a repeated exposure to H2O2 before irradiation the yield of aberrations was that expected from the combined treatment.

Cells, Cultured↗

PubMed1969