Two distinct subgroups of Group B Sox genes for transcriptional activators and repressors: their expression during embryonic organogenesis of the chicken

Mech Dev. 1999 Jun;84(1-2):103-20. doi: 10.1016/s0925-4773(99)00083-0.


Group B Sox genes, Sox1, -2 and -3 are known to activate crystallin genes and to be involved in differentiation of lens and neural tissues. Screening of chicken genomic sequences for more Group B Sox genes identified two additional genes, Sox14 and Sox21. Proteins encoded by Sox14 and Sox21 genes are similar to each other but distinct from those coded by Sox1-3 (subgroup B1) except for the HMG domain and Group B homology immediately C-proximal of the HMG domain. C-terminal domains of SOX21 and SOX14 proteins function as strong and weak repression domains, respectively, when linked to the GAL4 DNA binding domain. These SOX proteins strongly (SOX21) or moderately (SOX14) inhibited activation of delta1-crystallin DC5 enhancer by SOX1 or SOX2, establishing that Sox14 and Sox21 are repressing subgroup (B2) of Group B Sox genes. This provides the first evidence for the occurrence of repressor SOX proteins. Activating (B1) and repressing (B2) subgroups of Group B Sox genes display interesting overlaps of expression domains in developing tissues (e.g. optic tectum, spinal cord, inner ear, alimentary tract, branchial arches). Within each subgroup, most expression domains of Sox1 and -3 are included in those of Sox2 (e.g. CNS, PNS, inner ear), while co-expression of Sox14 and Sox21 occurs in highly restricted sites of the CNS, with the likely temporal order of Sox21 preceding Sox14 (e.g. interneurons of the spinal cord). These expression patterns suggest that target genes of Group B SOX proteins are finely regulated by the counterbalance of activating and repressing SOX proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Brain / embryology
  • Brain / metabolism
  • Branchial Region / embryology
  • Branchial Region / metabolism
  • Chick Embryo
  • Cloning, Molecular
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Ear, Inner / embryology
  • Ear, Inner / metabolism
  • Ectoderm / metabolism
  • Gene Expression Regulation, Developmental*
  • HMGB Proteins
  • High Mobility Group Proteins / genetics*
  • High Mobility Group Proteins / metabolism
  • Molecular Sequence Data
  • Neoplasm Proteins / genetics*
  • Neoplasm Proteins / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Repressor Proteins / genetics*
  • Repressor Proteins / metabolism
  • Rhombencephalon / embryology
  • Rhombencephalon / metabolism
  • SOXB1 Transcription Factors
  • SOXB2 Transcription Factors
  • Sense Organs / embryology
  • Sense Organs / metabolism
  • Sequence Homology, Amino Acid
  • Spinal Cord / embryology
  • Spinal Cord / metabolism
  • Trans-Activators / genetics*
  • Trans-Activators / metabolism
  • Transcription Factors*


  • DNA-Binding Proteins
  • HMGB Proteins
  • High Mobility Group Proteins
  • Neoplasm Proteins
  • Nuclear Proteins
  • Repressor Proteins
  • SOX1 protein, human
  • SOXB1 Transcription Factors
  • SOXB2 Transcription Factors
  • Sox14 protein, mouse
  • Sox2 protein, mouse
  • Sox21 protein, Gallus gallus
  • Sox3 protein, mouse
  • Trans-Activators
  • Transcription Factors

Associated data

  • GENBANK/AB026622
  • GENBANK/AB026623