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

Nat Genet. 2001 Jan;27(1):94-8. doi: 10.1038/83829.


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. The mechanisms that control which opsin is expressed in a particular cone are poorly understood, but previous in vitro studies implicated thyroid hormone in cone differentiation. Thyroid hormone receptor beta 2 (TR beta 2) is a ligand-activated transcription factor that is expressed in the outer nuclear layer of the embryonic retina. Here we delete Thrb (encoding Tr beta 2) 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 Tr beta 2 in the commitment to an M-cone identity. Our findings raise the possibility that Thrb mutations may be associated with human cone disorders.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Count
  • Color
  • Electroretinography
  • Gene Deletion
  • Gene Expression Regulation, Developmental
  • Gene Targeting
  • Immunohistochemistry
  • Mice
  • Mice, Knockout
  • RNA, Messenger / analysis
  • RNA, Messenger / genetics
  • Radioimmunoassay
  • Receptors, Thyroid Hormone / chemistry
  • Receptors, Thyroid Hormone / deficiency
  • Receptors, Thyroid Hormone / genetics
  • Receptors, Thyroid Hormone / metabolism*
  • Retinal Cone Photoreceptor Cells / abnormalities
  • Retinal Cone Photoreceptor Cells / embryology*
  • Retinal Cone Photoreceptor Cells / metabolism
  • Retinal Cone Photoreceptor Cells / physiology
  • Rod Opsins / genetics
  • Thyroid Hormones / analysis
  • Thyrotropin / analysis


  • RNA, Messenger
  • Receptors, Thyroid Hormone
  • Rod Opsins
  • Thyroid Hormones
  • Thyrotropin