Parallel regulation of fetal gene expression in different photoreceptor cell types.
Transcriptional induction for multiple bovine rod-specific photoreceptor genes has been shown to coincide with the first emergence of rod outer segments (two-thirds gestation) suggesting a coordinate regulation of these genes. Since cone visual transduction proteins are encoded for by distinct genes and mammalian cone cell genesis has been found to precede rod cell genesis it is important to determine when induction of photoreceptor-specific gene expression occurs in cone cells and how the timing of this event compares to that in rods. RNase protection assays specific for each cell type-specific gene were used to compare mRNA levels for bovine rod and blue cone gamma subunits of cGMP phosphodiesterase and rhodopsin and red cone opsin from before transcriptional induction (4 months gestation) to the adult. Both pairs of rod and cone visual transduction mRNAs exhibit indistinguishable transcriptional induction points at around 6 months of gestation. Before this time, transcripts of all four genes are present at low, but detectable levels. Thus, although rod and cone cells are distinct cell types and cone cells may be committed well before rod cells early in development, during the final trimester when elaboration of outer segments begins, there appears to be a coordinated regulation of both rod- and cone-specific visual transduction genes.
van Ginkel
P R
PR
Department of Immunology and Medical Microbiology, University of Florida, Gainesville 32610.
Hauswirth
W W
WW
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000096:biosynthesis*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism; D002417:Cattle; D002540:Cerebral Cortex / Q000378:metabolism; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000235:genetics; D017931:DNA Primers; D005314:Embryonic and Fetal Development; D005260:Female; D005333:Fetus; D005786:Gene Expression Regulation; D005865:Gestational Age; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009928:Organ Specificity; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism*; D017949:Retinal Cone Photoreceptor Cells / Q000201:enzymology / Q000378:metabolism*; D017948:Retinal Rod Photoreceptor Cells / Q000196:embryology / Q000378:metabolism*; D012243:Rhodopsin / Q000096:biosynthesis*; D012374:Rod Cell Outer Segment / Q000378:metabolism; D017299:Rod Opsins / Q000096:biosynthesis*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D017931:DNA Primers; D046911:Macromolecular Substances; D012333:RNA, Messenger; D017299:Rod Opsins; D004247:DNA; D012243:Rhodopsin; D015106:3',5'-Cyclic-GMP Phosphodiesterases