Myosin heavy chain (MHC) genes are expressed as several distinct isoforms in a tissue-and stagespecific manner; three skeletal muscle MHC isoforms appear sequentially during development. We have isolated cDNA clones, identified by RNA blot hybridization and by nucleotide sequence determination as coding for portions of the embryonic (pMHC2.2), perinatal (pMHC16.2A), and a(V1) cardiac (pMHC141 and pMHC101) MHC isoforms. These four probes and the adult skeletal MHC probe (pMHC32) have been used on Southern blots of genomic DNA to detect restriction fragment length polymorphisms defining the alleles for these genes in mouse species Mus musculus and Mus spretus. In this way, we followed the segregation of skeletal and cardiac MHC genes in 42 offspring resulting from an interspecies backcross. We found that (i) the embryonic, perinatal, and adult skeletal MHC genes are clustered on chromosome 11 near the locus nude, (it) the skeletal and cardiac MHC genes do not cosegregate, and (iii) the a(V1) cardiac MHC gene is located on chromosome 14 close to Np-i. This result is in contrast to that for other contractile protein genes such as the alkali myosin light chain and the actin multigene families, which are dispersed in the genome.The myosin heavy chain (MHC) family in mammals consists of at least 11 isoforms: 1 superfast skeletal, 2 adult fast skeletal, 1 perinatal skeletal, 1 embryonic/fetal skeletal, 2 cardiac [a(V1) and f(V3)], 1 adult slow skeletal, 1 smooth muscle, and 2 nonmuscle (1). Analysis of mRNA and genomic DNA sequences has provided evidence for the presence of different MHC genes (2, 3-7). During skeletal muscle development there is a sequential transition of different skeletal MHC isoforms from embryonic/fetal MHC to perinatal MHC and finally to adult MHC, as demonstrated in the rat (8). This phenomenon has also been shown at the mRNA level in the rat (9) and in the mouse, where a fetal MHC mRNA is replaced by an adult MHC mRNA at birth (2). A similar situation prevails for the two cardiac myosin isoforms, V1 (aa homodimer) and V3 (P3P homodimer): V3 is predominant over V1 in fetal heart ventricles and is replaced by V1 after birth in the mouse (10). In contrast to the sequential expression of MHC genes during striated muscle development, myosin alkali light chain (alkali MLC) genes and actin genes exhibit coexpression of the adult protein with the corresponding fetal isoform (refs. 11 and 12 and unpublished data). In these cases, the fetal isoform is also expressed in adult cardiac tissue. Based on a chromosomal analysis of hybrid cell lines, it has been reported that the genes coding for skeletal a-actin, cardiac a-actin, cytoplasmic f-actin, and the skeletal isoform of MLC2 are located on different mouse chromosomes (13, 14), whereas all the MHC genes are on chromosome 11 (13,15). Using backcrosses of an interspecies Mus 1 (DBA/2) x Mus 3 (M. spretus) cross and following the Mendelian segregation of muscle-specific genes by restriction fragment length polymorphism (RFLP), Robert et al. (16) d...
A recombinant plasmid with a cDNA sequence transcribed from mouse skeletal muscle RNA is shown to hybridize with mRNAs for myosin light chains LC1F and LC3F. The inserted fragment corresponds exclusively to the 3'-noncoding region ofthe mRNA. It hybridizes almost exclusively with the two light chain messengers from fast skeletal muscle RNA of adult mouse. Slight hybridization is seen with RNA from heart muscle and embryonic skeletal muscle. The implications ofthe conservation ofthe 3'-noncoding regions between the two mRNAs are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.