title: Thyroid hormone controls cone opsin expression in the retina of adult rodents.
abstract: Mammalian retinas display an astonishing diversity in the spatial arrangement of their spectral cone photoreceptors, probably in adaptation to different visual environments. Opsin expression patterns like the dorsoventral gradients of short-wave-sensitive (S) and middle- to long-wave-sensitive (M) cone opsin found in many species are established early in development and thought to be stable thereafter throughout life. In mouse early development, thyroid hormone (TH), through its receptor TRβ2, is an important regulator of cone spectral identity. However, the role of TH in the maintenance of the mature cone photoreceptor pattern is unclear. We here show that TH also controls adult cone opsin expression. Methimazole-induced suppression of serum TH in adult mice and rats yielded no changes in cone numbers but reversibly altered cone patterns by activating the expression of S-cone opsin and repressing the expression of M-cone opsin. Furthermore, treatment of athyroid Pax8(-/-) mice with TH restored a wild-type pattern of cone opsin expression that reverted back to the mutant S-opsin-dominated pattern after termination of treatment. No evidence for cone death or the generation of new cones from retinal progenitors was found in retinas that shifted opsin expression patterns. Together, this suggests that opsin expression in terminally differentiated mammalian cones remains subject to control by TH, a finding that is in contradiction to previous work and challenges the current view that opsin identity in mature mammalian cones is fixed by permanent gene silencing.
authors: Max Planck Institute for Brain Research, Neuroscience Center, Goethe-Universität, 60528 Frankfurt/Main, Germany.
authors: Anika
authors: A
authors: Glaschke
authors: Jessica
authors: J
authors: Weiland
authors: Domenico
authors: D
authors: Del Turco
authors: Marianne
authors: M
authors: Steiner
authors: Leo
authors: L
authors: Peichl
authors: Martin
authors: M
authors: Glösmann
mesh_terms: D000367:Age Factors; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D055358:Cone Opsins / Q000096:biosynthesis*; D005786:Gene Expression Regulation; D007037:Hypothyroidism / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics; D051381:Rats; D011914:Rats, Inbred BN; D012160:Retina / Q000378:metabolism*; D017299:Rod Opsins / Q000096:biosynthesis*; D013963:Thyroid Hormones / Q000502:physiology*
chemical_list: D055358:Cone Opsins; D000072636:PAX8 Transcription Factor; D051761:Paired Box Transcription Factors; C499496:Pax8 protein, mouse; D017299:Rod Opsins; D013963:Thyroid Hormones; C095853:short-wavelength opsin