Molecular cloning of the human Hand1 gene/cDNA and its tissue-restricted expression in cytotrophoblastic cells and heart

• Published in: Gene 1998-12, Vol.224 (1), p.77-86
• Main Authors: Knöfler, Martin, Meinhardt, Gudrun, Vasicek, Richard, Husslein, Peter, Egarter, Christian
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Base Sequence; Basic Helix-Loop-Helix Transcription Factors; bHLH protein, tissue-specific mRNA expression; Cloning of human Hand1 gene/cDNA; Cloning, Molecular; DNA - chemistry; DNA - genetics; DNA - isolation & purification; DNA, Complementary - chemistry; DNA, Complementary - genetics; DNA, Complementary - isolation & purification; DNA-Binding Proteins - genetics; Gene Expression Regulation, Developmental; Genes - genetics; Humans; Molecular Sequence Data; Myocardium - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Tissue Distribution; Transcription Factors - genetics; Trophoblast cells; Trophoblasts - cytology; Trophoblasts - metabolism
• ISSN: 0378-1119; 1879-0038
• DOI: 10.1016/S0378-1119(98)00511-3

The basic helix–loop–helix (bHLH) factor Hand1 plays a role in the developing chicken heart and is required for trophoblast giant cell differentiation and cardiac looping of mouse embryonic development. Here, we report the cloning of the human Hand1 cDNA and gene from a heart-specific cDNA library and a genomic λ-DNA library, respectively. We present the nucleotide sequence of a 1.75 kb cDNA clone, encoding the presumptive 215 amino acid human Hand1 protein, and show homology comparison of the conserved bHLH region between different species. In vitro transcription–translation of Hand1 mRNA and analysis of protein size suggest that the Hand1 polypeptide is (post)translationally modified. By Southern blot analysis we demonstrate that the isolated genomic DNA clone harbours the entire Hand1 gene and describe molecular structure and sequences of the two 799 and 938 bp exons and the single 1.56 kb intron. The expression pattern of the mRNA in different human tissues revealed that Hand1 transcripts are restricted to the heart, suggesting that the protein could be required for cardiac-specific gene transcription and function in adults. Hand1 transcripts were undetectable in a non-tumorigenic villous trophoblast cell line, immunopurified cytotrophoblasts undergoing in vitro differentiation, and first trimester placental tissue, suggesting that the transcription factor is not involved in the development of villous and extravillous trophoblast cell lineages. Hand1 mRNA, however, was abundantly expressed in cytotrophoblastic Jeg-3 and BeWo cells, suggesting that Hand1 could be required for early trophoblast differentiation.