title: Thyroid hormone action is required for normal cone opsin expression during mouse retinal development.
abstract: OBJECTIVE
  The expression of S- and M-opsins in the murine retina is altered in different transgenic mouse models with mutations in the thyroid hormone receptor (TR)-beta gene, demonstrating an important role of thyroid hormone (TH) in retinal development.
  
  
  METHODS
  The spatial expression of S- and M-opsin was compared in congenital hypothyroidism and in two different TR mutant mouse models. One mouse model contains a ligand-binding mutation that abolishes TH binding and results in constitutive binding to nuclear corepressors. The second model contains a mutation that blocks binding of coactivators to the AF-2 domain without affecting TH binding.
  
  
  RESULTS
  Hypothyroid newborn mice showed an increase in S-opsin expression that was completely independent of the genotype. Concerning M-opsin expression, hypothyroidism caused a significant decrease (P < 0.01) only in wild-type animals. When TRbeta1 and -beta2 were T3-binding defective, the pattern of opsin expression was similar to TRbeta ablation, showing increased S-opsin expression in the dorsal retina and no expression of M-opsin in the entire retina. In an unexpected finding, immunostaining for both opsins was detected when both subtypes of TRbeta were mutated in the helix 12 AF-2 domain.
  
  
  CONCLUSIONS
  The results show, for the first time, that the expression of S- and M-opsin is dependent on normal thyroid hormone levels during development.
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, Brazil.
authors.forename: Cristiano N
authors.initials: CN
authors.lastname: Pessôa
authors.forename: Leticia A
authors.initials: LA
authors.lastname: Santiago
authors.forename: Diana A
authors.initials: DA
authors.lastname: Santiago
authors.forename: Danielle S
authors.initials: DS
authors.lastname: Machado
authors.forename: Fernando A F
authors.initials: FA
authors.lastname: Rocha
authors.forename: Dora F
authors.initials: DF
authors.lastname: Ventura
authors.forename: Jan Nora
authors.initials: JN
authors.lastname: Hokoç
authors.forename: Carmen C
authors.initials: CC
authors.lastname: Pazos-Moura
authors.forename: Fredric E
authors.initials: FE
authors.lastname: Wondisford
authors.forename: Patricia F
authors.initials: PF
authors.lastname: Gardino
authors.forename: Tania M
authors.initials: TM
authors.lastname: Ortiga-Carvalho
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002452:Cell Count; D003409:Congenital Hypothyroidism / Q000378:metabolism*; D004195:Disease Models, Animal; D004596:Electroretinography; D005260:Female; D007124:Immunoenzyme Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation; D012160:Retina / Q000254:growth & development* / Q000378:metabolism; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism*; D017299:Rod Opsins / Q000378:metabolism*; D037042:Thyroid Hormone Receptors beta / Q000235:genetics; D013963:Thyroid Hormones / Q000502:physiology*
chemical_list: D017299:Rod Opsins; D037042:Thyroid Hormone Receptors beta; D013963:Thyroid Hormones; C095854:middle-wavelength opsin; C095853:short-wavelength opsin