Expression of novel opsins and intrinsic light responses in the mammalian retinal ganglion cell line RGC-5. Presence of OPN5 in the rat retina.
The vertebrate retina is known to contain three classes of photoreceptor cells: cones and rods responsible for vision, and intrinsically photoresponsive retinal ganglion cells (RGCs) involved in diverse non-visual functions such as photic entrainment of daily rhythms and pupillary light responses. In this paper we investigated the potential intrinsic photoresponsiveness of the rat RGC line, RGC-5, by testing for the presence of visual and non-visual opsins and assessing expression of the immediate-early gene protein c-Fos and changes in intracellular Ca(2+) mobilization in response to brief light pulses. Cultured RGC-5 cells express a number of photopigment mRNAs such as retinal G protein coupled receptor (RGR), encephalopsin/panopsin (Opn3), neuropsin (Opn5) and cone opsin (Opn1mw) but not melanopsin (Opn4) or rhodopsin. Opn5 immunoreactivity was observed in RGC-5 cells and in the inner retina of rat, mainly localized in the ganglion cell layer (GCL). Furthermore, white light pulses of different intensities and durations elicited changes both in intracellular Ca(2+) levels and in the induction of c-Fos protein in RGC-5 cell cultures. The results demonstrate that RGC-5 cells expressing diverse putative functional photopigments display intrinsic photosensitivity which accounts for the photic induction of c-Fos protein and changes in intracellular Ca(2+) mobilization. The presence of Opn5 in the GCL of the rat retina suggests the existence of a novel type of photoreceptor cell.
CIQUIBIC (CONICET)-Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
Paula S
PS
Nieto
Diego J
DJ
Valdez
Victoria A
VA
Acosta-Rodríguez
Mario E
ME
Guido
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D016257:Fura-2 / Q000031:analogs & derivatives / Q000378:metabolism; D005786:Gene Expression Regulation / Q000528:radiation effects; D057809:HEK293 Cells; D006801:Humans; D007150:Immunohistochemistry; D008027:Light; D055355:Opsins / Q000235:genetics / Q000378:metabolism*; D010775:Photic Stimulation; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects*
D055355:Opsins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; C049925:fura-2-am; D002118:Calcium; D016257:Fura-2