Characterization of cAMP/PKA/CREB signaling cascade in the bonnet monkey corpus luteum: expressions of inhibin-alpha and StAR during different functional status.
Luteinizing hormone mediates its nuclear action primarily by activating cAMP/Protein kinase A (PKA) pathway leading to phosphorylation of cAMP response element binding (CREB) family of transcription factors. Earlier studies have documented altered cAMP responsiveness of luteal cells during maturation, and in the rhesus monkey, extinction of CREB expression following luteinization and ovulation. In the course of studies aimed at characterizing LH-cAMP signaling pathway, we serendipitously discovered that CREB is after all present in the monkey corpus luteum (CL). The present experiments were carried out to examine the PKA activity, CREB expression and RT-PCR expression of inhibin-alpha (Inh-alpha) subunit and steroidogenic acute regulatory protein (StAR) in CL obtained from a variety of model systems. PKA activity in the CL was maintained throughout the luteal phase. Messenger RNA expression by RT-PCR and Northern analyses and protein levels employing antibodies specific to total- and phospho-forms demonstrated presence of CREB in the CL. Additionally, immuno-histo/cytochemical analyses, Electrophoretic mobility shift assays and chromatin immunoprecipitation assays for Inh-alpha and StAR genes further confirmed the presence of CREB in the CL. The present study, contrary to an earlier report, demonstrates the presence of CREB (both transcript and protein) in the monkey CL. Also, analysis of expression of Inh-alpha and StAR genes (considered to be cAMP responsive), during different functional status of CL suggests that LH regulates their expression perhaps by cAMP/PKA/CREB pathway.
Priyanka
S
S
Department of Molecular Reproduction, Development and Genetics Indian Institute of Science, Bangalore 560012, India.
Medhamurthy
R
R
D000818:Animals; D001483:Base Sequence; D003338:Corpus Luteum / Q000378:metabolism* / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D015151:Immunoblotting; D007265:Inhibins / Q000737:chemistry / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D008255:Macaca radiata; D008597:Menstrual Cycle / Q000378:metabolism; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism*; D010758:Phosphorus / Q000097:blood; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D015398:Signal Transduction; D000098682:Steroidogenic Acute Regulatory Protein
D017362:Cyclic AMP Response Element-Binding Protein; D010750:Phosphoproteins; C094377:inhibin-alpha subunit; D000098682:Steroidogenic Acute Regulatory Protein; D010758:Phosphorus; D007265:Inhibins; D007986:Luteinizing Hormone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases