Differential regulation of the cell cycle by alpha1-adrenergic receptor subtypes.
Alpha(1)-Adrenergic receptors have been implicated in growth-promoting pathways. A microarray study of individual alpha(1)-adrenergic receptor subtypes (alpha(1A), alpha(1B), and alpha(1D)) expressed in Rat-1 fibroblasts revealed that epinephrine altered the transcription of several cell cycle regulatory genes in a direction consistent with the alpha(1A)- and alpha(1D)-adrenergic receptors mediating G(1)-S cell cycle arrest and the alpha(1B-)mediating cell-cycle progression. A time course indicated that in alpha(1A) cells, epinephrine stimulated a G(1)-S arrest, which began after 8 h of stimulation and maximized at 16 h, at which point was completely blocked with cycloheximide. The alpha(1B)-adrenergic receptor profile also showed unchecked cell cycle progression, even under low serum conditions and induced foci formation. The G(1)-S arrest induced by alpha(1A)- and alpha(1D)-adrenergic receptors was associated with decreased cyclin-dependent kinase-6 and cyclin E-associated kinase activities and increased expression of the cyclin-dependent kinase inhibitor p27(Kip1), all of which were blocked by prazosin. There were no differences in kinase activities and/or expression of p27(Kip1) in epinephrine alpha(1B)-AR fibroblasts, although the microarray did indicate differences in p27(Kip1) RNA levels. Cell counts proved the antimitotic effect of epinephrine in alpha(1A) and alpha(1D) cells and indicated that alpha(1B)-adrenergic receptor subtype expression was sufficient to cause proliferation of Rat-1 fibroblasts independent of agonist stimulation. Analysis in transfected PC12 cells also confirmed the alpha(1A)- and alpha(1B)-adrenergic receptor effect. The alpha(1B)-subtype native to DDT1-MF2 cells, a smooth muscle cell line, caused progression of the cell cycle. These results indicate that the alpha(1A)- and alpha(1D)-adrenergic receptors mediate G(1)-S cell-cycle arrest, whereas alpha(1B)-adrenergic receptor expression causes a cell cycle progression and may induce transformation in sensitive cell lines.
The Department of Molecular Cardiology NB50, The Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio 44195, USA.
Pedro J
PJ
Gonzalez-Cabrera
Ting
T
Shi
June
J
Yun
Dan F
DF
McCune
Boyd R
BR
Rorabaugh
Dianne M
DM
Perez
D000322:Adrenergic Agonists / Q000494:pharmacology; D000818:Animals; D002452:Cell Count; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology* / Q000502:physiology; D005434:Flow Cytometry; D016193:G1 Phase / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000502:physiology; D016716:PC12 Cells; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics / Q000378:metabolism*; D016196:S Phase / Q000187:drug effects / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D000322:Adrenergic Agonists; C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D018340:Receptors, Adrenergic, alpha-1; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases; D004837:Epinephrine