Kilpirauhashormonin reseptorin tärkeys vihreän värin näkemisessä.

• Published: January 2001

A thyroid hormone receptor that is required for the development of green cone photoreceptors

• Lily Ng,, James B. Hurley et al.
  

Abstract. Color vision is facilitated by distinct populations of cone photoreceptors in the retina. In rodents, cones expressing different opsin photopigments are sensitive to middle (M, 'green') and short (S, 'blue') wavelengths, and are differentially distributed across the retina^1,2. The mechanisms that control which opsin is expressed in a particular cone are poorly understood^2,3, but previous in vitro studies implicated thyroid hormone in cone differentiation^4,5. Thyroid hormone receptor β2 (TRβ2) is a ligand-activated transcription factor that is expressed in the outer nuclear layer of the embryonic retina^6,7. Here we delete Thrb (encoding Trβ2) in mice, causing the selective loss of M-cones and a concomitant increase in S-opsin immunoreactive cones. Moreover, the gradient of cone distribution is disturbed, with S-cones becoming widespread across the retina. The results indicate that cone photoreceptors throughout the retina have the potential to follow a default S-cone pathway and reveal an essential role for Trβ2 in the commitment to an M-cone identity. Our findings raise the possibility that Thrb mutations may be associated with human cone disorders⁸.