Showing papers by "Gaby Palmer published in 1999"
TL;DR: Different roles for ERK and p38 MAP kinase pathways in regulating activity of MC3T3-E1 osteoblastic cells are suggested, with the ERK pathway likely involved in the control of cell proliferation whereas the p38MAP kinase pathway regulates ALP activity in response to activation of Gi protein-coupled receptors.
Abstract: The signaling mechanisms responsible for the regulation of alkaline phosphatase (ALP) activity by exogenous factors in osteoblast-like cells remain poorly understood. Among various agents, epinephrine was recently found to increase ALP activity in differentiating MC3T3-E1 cells by stimulating alpha1 adrenergic receptors coupled to Gi proteins. In the present study, we investigated the role of both ERK2 and p38 mitogen-activated protein (MAP) kinases in mediating this response in MC3T3-E1 cells. Our results indicate that both MAP kinases are transiently stimulated by epinephrine in differentiating cells via a pertussis toxin sensitive mechanism. The role of each MAP kinase pathway in mediating the stimulation of ALP activity by epinephrine was investigated using specific inhibitors. The MEK inhibitor PD98059, blocked ERK2 activity induced by epinephrine but had no effect on the stimulation of ALP activity. In contrast, low concentrations of SB203580, a specific inhibitor of the p38 MAP kinase, completely blunted this cellular response. However, this inhibitor had no influence on the stimulation of ALP activity induced by ascorbic acid. In conclusion, the results of this study suggest distinct roles for ERK and p38 MAP kinase pathways in regulating activity of MC3T3-E1 osteoblastic cells. The ERK pathway is likely involved in the control of cell proliferation whereas the p38 MAP kinase pathway regulates ALP activity in response to activation of Gi protein-coupled receptors.
102 citations
TL;DR: The Glvr-1 phosphate transporter is selectively expressed in a subset of hypertrophic chondrocytes during endochondral bone formation, in a region where matrix mineralization proceeds, the first in vivo evidence consistent with a potential role for this phosphate transporter in matrix calcification.
93 citations
TL;DR: The description of the human Glvr-1 gene structure, as well as the analysis of some structural and functional characteristics of its promoter region, provide a basis for more detailed investigation of the molecular mechanisms controlling expression of the Glvr -1 gene in bone forming cells and in other cell types.
13 citations
Journal Article•
2 citations