Genomic structure, chromosomal localization, and expression pattern of thehuman LIM-Homeobox3 (LHX 3) gene

Lhx3 is a LIM-homeobox protein essential for pituitary development in mice. The human homologue gene spans 7.2 kb and contains 7 exons, including two alternatively spliced first exons. This structure encodes two distinct prot ein isoforms, LHX3a and LHX3b, that differ exclusively in their amino-termi nus. The LHX3 gene was localized at 9q34.2-34.3. The predicted protein sequ ence is highly homologous to other known Lhx3 proteins, the highest degree of homology being in the conserved domains. The highest expression of LHX3 was found in pituitary gland, spinal cord, and lung. Among different pituit ary cell types, corticotrophs appear to express preferentially LHX3b isofor m, suggesting a distinct role of the b-form in the development of this cell lineage. Although the human LHX3 gene structure would provide a ground for clarification of the molecular basis of complete anterior pituitary defici ency, we were unable to identify any mutation in the LHX3 gene of 46 such p atients. (C) 2000 Academic Press.