Expression of slow skeletal myosin heavy chain 2 gene in Purkinje fiber cells in chick heart.
In avian, there are three slow skeletal myosin heavy chain (MHC) isoforms, slow skeletal MHC 1, 2, and 3. While slow skeletal MHC 3 has been characterized, slow skeletal MHC 1 and 2 are not yet fully studied. To determine the complete sequence of slow skeletal MHC 2, we isolated six overlapping cDNA clones, each encoding a portion of chick slow skeletal MHC 2, using the reverse transcription polymerase chain reaction (RT-PCR). The entire slow skeletal MHC 2 cDNA consisted of 5927 nucleotides including a 104 bp 3'-untranslated region and encoded 1941 amino acids. Using one of the cDNA clones, we made a probe for in situ hybridization. We also used immunohistochemistry to localize slow skeletal MHC 2 in skeletal and cardiac tissues. These studies showed that in addition to its expected expression in the adult chicken slow skeletal muscle, slow skeletal MHC 2 was expressed in the subendocardial cluster of cells and around the blood vessels within the ventricle of late embryos and adults. This isoform was not expressed in the myocardium throughout the life of the chicken. Based on morphological criteria as well as rich desmin expression, we concluded that the subendocardial cluster of cells were Purkinje cells. Although the physiological significance of the slow skeletal MHC expression remains elusive at this time, this MHC isoform may be used as a specific marker for Purkinje cells.
Machida
Shuichi
S
Department of Pediatric Cardiology, The Heart Institute of Japan, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan.
Noda
Setsuko
S
Takao
Atsuyoshi
A
Nakazawa
Makoto
M
Matsuoka
Rumiko
R
D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D002645:Chickens; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000196:embryology; D006329:Heart Conduction System / Q000737:chemistry / Q000166:cytology / Q000196:embryology; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry / Q000166:cytology; D018995:Myosin Heavy Chains / Q000096:biosynthesis / Q000235:genetics*; D020033:Protein Isoforms; D011690:Purkinje Fibers / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014018:Tissue Distribution
D020033:Protein Isoforms; D012333:RNA, Messenger; D018995:Myosin Heavy Chains