Stimulation of the mitogen-activated protein kinase (MAPK) pathway in DDT1MF-2 cells by adenosine A1 receptors and histamine H1 receptors

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Robinson, A.J., 2002. Stimulation of the mitogen-activated protein kinase (MAPK) pathway in DDT1MF-2 cells by adenosine A1 receptors and histamine H1 receptors. PhD, Nottingham Trent University.

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Abstract

The mitogen-activated protein kinases (MAPKs) are a group of serine/threonine protein kinases comprising of three main subfamilies. Extracellular signal-regulated kinases (ERKs 1/2, or p42/p44 MAPKs) are primarily associated with the regulation of cell proliferation and differentiation, whereas the c-jun N-terminal kinases (JNKs/SAPKs) and p38 MAPKs are involved in apoptosis, inflammation, and responses to environmental stress. Adenosine A1 receptors (A1Rs; Gi/o-coupled) have been implicated in cardiac and neuronal protection, and histamine H1 receptors (H1Rs; Gq/11- coupled) mediate various physiological effects, such as vascular smooth muscle contraction. In this study the coupling of these two G protein-coupled receptors (GPCRs) to the three main MAPK cascades, and the possible physiological consequences, were investigated in the smooth muscle cell line DDT1MF-2.

Both A1Rs and H1Rs mediated ERK 1/2 activation in DDT1MF-2 cells. ERK 1/2 stimulation by A1Rs involved Gi/o proteins, PI-3K, and MEK1, but appeared to be independent of tyrosine kinase activation. H1R-mediated ERK 1/2 in DDT1MF-2 cells involved PI-3K, tyrosine kinases, PKC, MEK1, and, unexpectedly, Gi/o proteins. A1Rs and H1Rs also mediated p38 MAPK activation in DDT1MF-2 cells. Similar to ERK 1/2 activation, p38 MAPK activation by both A1Rs and H1Rs involved Gi/o proteins. However, neither the A1R nor the H1R activated the JNK/SAPK cascade in DDT1MF-2 cells.

Both A1R and H1R stimulation had no significant effect on DDT1MF-2 cell proliferation, and did not potentiate EGF-induced DDT1MF-2 cell growth. A1R stimulation also had no significant effect on FCS-mediated DDT1MF-2 cell proliferation. A1Rs and H1Rs had no significant effect on both staurosporine-and hydrogen peroxide-induced cell death. Also, both receptors had no significant effect on staurosporine-induced caspase-3 activation. For comparison, EGF did significantly reduce staurosporine-induced caspase- 3 activation.

In conclusion, this study has shown that A1Rs and H1Rs couple to the p42/p44 MAPK and p38 MAPK cascades in DDT1MF-2 cells. Since neither receptor induced or potentiated DDT1MF-2 cell proliferation, or inhibited caspase-3 activation, further experiments are required in order to establish the physiological roles of A1Rs and H1Rs in DDT1MF-2 cells.

Item Type:

Thesis

Creators:

Robinson, A.J.

Date:

2002

ISBN:

9781369314250

Identifiers: