VITO-1, a novel vestigial related protein is predominantly expressed in the skeletal muscle lineage

In order to identify novel genes expressed in skeletal muscle we performed a subtractive hybridization for genes expressed in human skeletal muscle but not in other tissues. We identified a novel scalloped interaction domain (SID) containing protein in humans and in the mouse, which we named VITO-1. Highest homology of VITO-1 was found with the Drosophila vestigial and the human TONDU proteins in the SID (54 and 40%, respectively). Using whole-mount hybridzation and Northern blot analysis, we showed that VITO-1 is expressed in the somitic myotome from E8.75 mouse embryos onwards and later on in skeletal muscle but not in the heart. Additional expression domains during development were detected in the pharyngeal pouches and clefts starting at E8.0 as well as in the cranial pharynx and in Rathkes pouch. By Northern blot analysis, we found VITO-1 to be up-regulated in C2C12 myotubes although some expression can be detected in proliferating C2C12 myoblasts. No expression was spotted in other adult mouse tissues. Likewise, expression of human Vito-1 during fetal and adult human development was found exclusively in skeletal muscle preferentially in fast skeletal muscles. These data suggest a role of VITO-1 for the development of skeletal muscles and of pharyngeal clefts/Rathkes' pouch derived structures.     

VITO-1, a novel vestigial related protein is predominantly expressed in the skeletal muscle lineage

In order to identify novel genes expressed in skeletal muscle we performed a subtractive hybridization for genes expressed in human skeletal muscle but not in other tissues. We identified a novel scalloped interaction domain (SID) containing protein in humans and in the mouse, which we named VITO-1. Highest homology of VITO-1 was found with the Drosophila vestigial and the human TONDU proteins in the SID (54 and 40%, respectively). Using whole-mount hybridzation and Northern blot analysis, we showed that VITO-1 is expressed in the somitic myotome from E8.75 mouse embryos onwards and later on in skeletal muscle but not in the heart. Additional expression domains during development were detected in the pharyngeal pouches and clefts starting at E8.0 as well as in the cranial pharynx and in Rathkes pouch. By Northern blot analysis, we found VITO-1 to be up-regulated in C2C12 myotubes although some expression can be detected in proliferating C2C12 myoblasts. No expression was spotted in other adult mouse tissues. Likewise, expression of human Vito-1 during fetal and adult human development was found exclusively in skeletal muscle preferentially in fast skeletal muscles. These data suggest a role of VITO-1 for the development of skeletal muscles and of pharyngeal clefts/Rathkes' pouch derived structures.     

Organization of the mouse microfibril-associated glycoprotein-2 (MAGP-2) gene

A 1.4-kb EST clone encoding mouse microfibril-associated glycoprotein-2 (MAGP-2), identified by its similarity with the reported human cDNA, was used to screen a mouse 129 genomic bacterial artificial chromosome (BAC) library. The mouse gene contains 10 exons spanning 16 kb, located on the distal region of Chromosome (Chr) 6. The exons range in size from 24 to 963 bp, with the ATG located in exon 2. The tenth and largest exon contains 817 bp of 3′ untranslated sequence, including a B2 repetitive element. Northern analysis demonstrates abundant expression of MAGP-2 mRNA in skeletal muscle, lung, and heart. Sequence analysis of additional cDNA clones suggests that the two mRNA forms of MAGP-2 in the mouse arise from alternative polyadenylation site usage. The promoter does not contain an obvious TATA box, and the sequence surrounding the start site does not conform to the consensus for an initiator promoter element. Additionally, the mouse promoter contains 22 copies of a CT dinucleotide repeat sequence located ∼155 bp 5′ to exon 1. Received: 27 August 1999 / Accepted: 2 November 1999     

Novel gene hKCNE4 slows the activation of the KCNQ1 channel

The KCNE genes encode small, single transmembrane domain peptides that associate with pore-forming potassium channel subunits to form mixed complexes with unique characteristics. We have identified a novel member of the human KCNE gene family, hKCNE4. The hKCNE4 gene encodes 170 amino acid protein and is localized to chromosome 2q35-36. The protein sequence shows 90% homology to mouse KCNE4 and 38% identity to human KCNE1. Northern blot analysis revealed that hKCNE4 is expressed strongly in heart, skeletal muscle, and kidney, less in placenta, lung, and liver, and weakly in brain and blood cells. Electrophysiological study showed that hKCNE4 modulates the activation of the KCNQ1 channel.