Characterization of Drosophila hibris, a gene related to human nephrin

• Published in: Development (Cambridge) Vol. 128; no. 21; pp. 4265 - 4276
• Main Authors: Dworak, H A, Charles, M A, Pellerano, L B, Sink, H
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Limited 01.11.2001
• Subjects: Amino Acid Sequence; Animals; Basic Helix-Loop-Helix Transcription Factors; Cloning, Molecular; DNA-Binding Proteins - genetics; Drosophila; Drosophila - embryology; Drosophila - genetics; Drosophila Proteins; dumbfounded gene; Embryo, Nonmammalian; Gene Expression Regulation, Developmental; hibris gene; Humans; Insect Proteins - genetics; Insect Proteins - metabolism; irregular chiasm-roughest gene; MEF2 Transcription Factors; Membrane Proteins - genetics; Membrane Proteins - metabolism; Mesoderm; Molecular Sequence Data; Muscle, Skeletal - cytology; Muscle, Skeletal - embryology; Mutation; Myogenic Regulatory Factors; nephrin; Nuclear Proteins - genetics; Proteins - genetics; Receptors, Notch; Sequence Homology, Amino Acid; sticks-and-stones gene; Transcription Factors - genetics
• ISSN: 0950-1991; 1477-9129
• DOI: 10.1242/dev.128.21.4265

Hibris encodes a protein that is a newly identified member of the immunoglobulin superfamily and has homology to vertebrate Nephrins and Drosophila Sticks-and-Stones. The Hibris protein has eight Ig-like domains, a fibronectin domain and a 160 amino acid cytoplasmic tail. The hibris transcript is expressed in a broad range of tissues and across life stages. In the embryo, hibris transcript is present in the mesectoderm, then in a group of cells at the developing CNS midline and in a subset of glia. In the periphery, hibris is expressed by fusion competent myoblasts and the epidermal muscle attachment site cells. Deletion analyses show that loss of hibris does not visibly affect embryonic CNS or somatic muscle development. However overexpressing hibris in the somatic mesoderm disrupts myoblast fusion. Furthermore, when overexpressed in the epidermis, Hibris causes comprehensive derangement of muscle insertion locations. A similar myoblast fusion defect is observed when the Drosophila homologs of DM-GRASP/BEN/SC1 (irregular chiasm-roughest and dumbfounded) are deleted together. Our S2 cell aggregation assays have revealed a heterotypic interaction between Hibris and Dumbfounded, but not between Hibris and Irregular Chiasm-Roughest. We propose that Hibris is an extracellular partner for Dumbfounded and potentially mediates the response of myoblasts to this attractant.