Cyclic AMP-dependent activation of rhodopsin gene transcription in cultured retinal precursor cells of chicken embryo.
The present study describes a robust 50-fold increase in rhodopsin gene transcription by cAMP in cultured retinal precursor cells of chicken embryo. Retinal cells isolated at embryonic day 8 (E8) and cultured for 3 days in serum-supplemented medium differentiated mostly into red-sensitive cones and to a lesser degree into green-sensitive cones, as indicated by real-time RT-PCR quantification of each specific opsin mRNA. In contrast, both rhodopsin mRNA concentration and rhodopsin gene promoter activity required the presence of cAMP-increasing agents [forskolin and 3-isobutyl-1-methylxanthine (IBMX)] to reach significant levels. This response was rod-specific and was sufficient to activate rhodopsin gene transcription in serum-free medium. The increase in rhodopsin mRNA levels evoked by a series of cAMP analogs suggested the response was mediated by protein kinase A, not by EPAC. Membrane depolarization by high KCl concentration also increased rhodopsin mRNA levels and this response was strongly potentiated by IBMX. The rhodopsin gene response to cAMP-increasing agents was developmentally gated between E6 and E7. Rod-specific transducin alpha subunit mRNA levels also increased up to 50-fold in response to forskolin and IBMX, while rod-specific phosphodiesterase-VI and rod arrestin transcripts increased 3- to 10-fold. These results suggest a cAMP-mediated signaling pathway may play a role in rod differentiation.
Voisin
Pierre
P
Institut de Physiologie et Biologie Cellulaires, Université de Poitiers, CNRS, Poitiers, France. pierre.voisin@univ-poitiers.fr
Bernard
Marianne
M
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D019393:Arrestin / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6 / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D017949:Retinal Cone Photoreceptor Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D017948:Retinal Rod Photoreceptor Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D012243:Rhodopsin / Q000096:biosynthesis / Q000235:genetics*; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects / Q000502:physiology*; D015293:Transducin / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
D019393:Arrestin; D010726:Phosphodiesterase Inhibitors; D012333:RNA, Messenger; D005576:Colforsin; D011189:Potassium Chloride; D012243:Rhodopsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6; D015293:Transducin; D015056:1-Methyl-3-isobutylxanthine