The mouse homeoprotein mLIM-3 is expressed early in cells derived from the neuroepithelium and persists in adult pituitary

DNA Cell Biol. 1994 Dec;13(12):1163-80. doi: 10.1089/dna.1994.13.1163.

Abstract

LIM-homeodomain proteins are important in cell lineage specification and possibly mediate transcriptional processes in eukaryotes. During the screening of a mouse pituitary cDNA library, we isolated a partial cDNA coding for a novel gene product that exhibited a predicted amino-terminal sequence similar to the homeobox of LIM-homeodomain-containing proteins. Reverse transcriptase-polymerase chain reactions (RT-PCR) performed on mouse pituitary mRNA using degenerate oligonucleotides based on the conserved LIM-domain sequences, allowed the extension of the 5' end of the sequence. The composite 2.2-kb cDNA structure predicts a 400-amino-acid-long novel mouse (m) protein, called mLIM-3. This name was chosen since within the 59-amino-acid homeodomain, it exhibits 97% sequence identity to a recently reported Xenopus homologue xLIM-3. The gene coding for mLIM-3 maps to the murine chromosome 2, most probably within the 2B band. Based on sequence characteristics, we suggest that LIM-3 belongs to a distinct subfamily of LIM-containing homeoproteins. Ontogeny studies using in situ hybridization demonstrated that mLIM-3 transcripts can be detected on embryonic day 11 (e11) in the primordium of the hypophysis. Following a maximum between e12 and e14, lower levels persisted into adulthood, where mLIM-3 was expressed primarily in the anterior and intermediate lobes of the pituitary. These results were confirmed by Northern blot analysis in adult mice which revealed a 2.4-kb pituitary mRNA transcript. mLIM-3 transcripts were also detected in pituitary cell lines such as the somatotrophs GH3 and GH4C1, the gonadotroph alpha T3-1, and the corticotroph AtT-20 cells, but not in 20 other cell lines derived from peripheral, endocrine, and neural tissues. Starting from e11, we also observed a transient expression of mLIM-3 in the ventral part of the spinal cord, pons, and medulla oblongata, reaching a maximum at e13 and from p7 onward, the expression of this transcript is no longer detectable. mLIM-3 is also expressed in the pineal gland with high levels observed at e20. These data suggest a potential role for mLIM-3 in the transcriptional regulation of certain genes during morphogenesis and/or maintenance of the differentiated state of the pituitary, motor neurons, and pineal gland.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Line
  • Central Nervous System / embryology
  • Central Nervous System / metabolism
  • Chromosome Mapping
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • DNA-Binding Proteins / genetics*
  • Embryonic and Fetal Development
  • Epithelium / metabolism
  • Female
  • Gene Expression Regulation, Developmental*
  • Homeodomain Proteins / genetics*
  • LIM-Homeodomain Proteins
  • Male
  • Mice
  • Molecular Sequence Data
  • Pituitary Gland / embryology
  • Pituitary Gland / metabolism*
  • RNA, Messenger / analysis
  • Sequence Alignment
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Transcription Factors

Substances

  • DNA, Complementary
  • DNA-Binding Proteins
  • Homeodomain Proteins
  • LIM-Homeodomain Proteins
  • Lhx3 protein
  • RNA, Messenger
  • Transcription Factors

Associated data

  • GENBANK/L33776