A novel marker for vertebrate embryonic heart, the EH-myomesin isoform.
Myomesin is a structural component of the M-band that is expressed in all types of striated muscle. Its primary function may be the maintenance of the thick filament lattice and its anchoring to the elastic filament system composed of titin. Different myomesin isoforms have been described in chicken and mice, but no particular function has been assigned to them. Here we investigate the spatio-temporal expression pattern of myomesin isoforms by means of reverse transcriptase-polymerase chain reaction and isoform-specific antibodies. We find that two alternative splicing events give rise to four myomesin isoforms in chicken contrary to only one splicing event with two possible isoforms in mice. A splicing event at the C terminus results in two splice variants termed H-myomesin and S-myomesin, which represent the major myomesin species in heart and skeletal muscle of avian species, respectively. In contrast, in mammalian heart and skeletal muscle only S-myomesin is expressed. In embryonic heart of birds and mammals, alternative splicing in the central part of the molecule gives rise to the isoform that we termed EH-myomesin. It represents the major myomesin isoform at early embryonic stages of heart but is rapidly down-regulated around birth. Thus, the strict developmental regulation of the EH-myomesin makes it an ideally suited marker for embryonic heart.
Agarkova
I
I
Institute of Cell Biology, ETH-Zürich Hönggerberg, CH-8093 Zürich, Switzerland.
Auerbach
D
D
Ehler
E
E
Perriard
J C
JC
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002642:Chick Embryo; D064211:Connectin; D005314:Embryonic and Fetal Development; D018507:Gene Expression Regulation, Developmental; D014644:Genetic Variation; D006321:Heart / Q000196:embryology*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000032:analysis / Q000235:genetics*; D009928:Organ Specificity; D020033:Protein Isoforms / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D015415:Biomarkers; D064211:Connectin; D009124:Muscle Proteins; D020033:Protein Isoforms