scholarly journals The expression of myosin genes in developing skeletal muscle in the mouse embryo.

1990 ◽  
Vol 111 (4) ◽  
pp. 1465-1476 ◽  
Author(s):  
G E Lyons ◽  
M Ontell ◽  
R Cox ◽  
D Sassoon ◽  
M Buckingham

Using in situ hybridization, we have investigated the temporal sequence of myosin gene expression in the developing skeletal muscle masses of mouse embryos. The probes used were isoform-specific, 35S-labeled antisense cRNAs to the known sarcomeric myosin heavy chain and myosin alkali light chain gene transcripts. Results showed that both cardiac and skeletal myosin heavy chain and myosin light chain mRNAs were first detected between 9 and 10 d post coitum (p.c.) in the myotomes of the most rostral somites. Myosin transcripts appeared in more caudal somites at later stages in a developmental gradient. The earliest myosin heavy chain transcripts detected code for the embryonic skeletal (MHCemb) and beta-cardiac (MHC beta) isoforms. Perinatal myosin heavy chain (MHCpn) transcripts begin to accumulate at 10.5 d p.c., which is much earlier than previously reported. At this stage, MHCemb is the major MHC transcript. By 12.5 d p.c., MHCpn and MHCemb mRNAs are present to an equal extent, and by 15.5 d p.c. the MHCpn transcript is the major MHC mRNA detected. Cardiac MHC beta transcripts are always present as a minor component. In contrast, the cardiac MLC1A mRNA is initially more abundant than that encoding the skeletal MLC1F isoform. By 12.5 d p.c. the two MLC mRNAs are present at similar levels, and by 15.5 d p.c., MLC1F is the predominant MLC transcript detected. Transcripts for the ventricular/slow (MLC1V) and another fast skeletal myosin light chain (MLC3F) are not detected in skeletal muscle before 15 d p.c., which marks the beginning of the fetal stage of muscle development. This is the first stage at which we can detect differences in expression of myosin genes between developing muscle fibers. We conclude that, during the development of the myotome and body wall muscles, different myosin genes follow independent patterns of activation and accumulation. The data presented are the first detailed study of myosin gene expression at these early stages of skeletal muscle development.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2869-2869
Author(s):  
Victor R. Gordeuk ◽  
Xu Zhang ◽  
Wei Zhang ◽  
Shwu-Fan Ma ◽  
Craig Sable ◽  
...  

Abstract Abstract 2869 Chuvash polycythemia (CP) is characterized by homozygosity for the R200W mutation in the von Hippel Lindau gene (VHL). This rare genetic disorder causes elevated levels of hypoxia inducible factor (HIF)-1 and HIF-2 that trigger constitutive hypoxia responses at normoxia. Hypoxia is a recognized cause of pulmonary hypertension. We recently reported that systolic pulmonary artery pressure (SPAP) estimated by echocardiography-determined tricuspid regurgitation velocity (TRV) was elevated in 120 CP patients compared to 31 Chuvash controls (P = 0.005), and that increasing age (P = 0.001), increasing systemic pulse pressure (P = 0.003) and lower serum ferritin concentration (P = 0.009) were independent predictors of higher estimated SPAP in CP patients [Sable et al., 2012]. In this study, we profiled gene expression for 16,642 genes in peripheral blood mononuclear cells (PBMCs) derived from a cohort of 43 CP patients, and measured the TRV for these individuals. Based on a prospectively chosen criterion of TRV ≥2.5 m/sec, 20 patients were classified as having elevated level of estimated SPAP and 23 were normal. Gene expression level between these two SPAP groups appeared to be homogenous. However, we identified 4777 genes at false discovery rate (FDR) <0.05 that exhibit pulse pressure by SPAP group interaction, suggesting a profound difference in pulse pressure regulation between the two SPAP groups. Further analysis of probe level data revealed a potential genetic polymorphism located within exon 7 of SERPINC1, encoding antithrombin III, at a site where a disease-associated SNP has not been reported. The minor allele of this polymorphism, which we designated “B”, was highly enriched in the elevated estimated SPAP group (P=0.0009), and classification based on the putative SERPINC1 genotypes strengthens the interaction effect with pulse pressure. Analysis of the gene expression data for the 43 CP patients with an additive genetic model of SERPINC1 identified 1902 differential genes at FDR <0.05. The 1120 genes up-regulated by the B allele were highly enriched in the Reactome G-protein coupled receptor pathway (Padjusted < 8×10−10). Several genes involved in smooth muscle contraction, regulation of blood pressure, and angiogenesis were up-regulated by the putative B allele, for example, HTR5A (serotonin receptor 5A), TAC3 (tachykinin 3), ADRA1D (adrenergic alpha-1D- receptor), BDKRB1 (bradykinin receptor B1), BDKRB2 (bradykinin receptor B1), EDN2 (endothelin 2), PTGER1 (prostaglandin E receptor 1), PTGIR (prostaglandin I2 receptor), APLNR (apelin receptor), RAMP2 (receptor activity modifying protein 2), MYH6 (myosin heavy chain 6), MYH7 (myosin heavy chain 7), MYL2 (myosin light chain 2), MYLK2 (myosin light chain kinase 2), MYLK3 (myosin light chain kinase 3), ACE (angiotensin I converting enzyme 1), ATP2A1 (ATPase cardiac muscle fast twitch 1), ADCY4 (adenylate cyclase 4), and PRKAA2 (protein kinase AMP-activated alpha 2 catalytic subunit). On the other hand, genes whose malfunction has been associated with familial pulmonary hypertension, including BMPR2 (bone morphogenetic protein receptor, type II), SMAD5 (SMAD family member 5), and ACVR2A (activin A receptor, type IIA), were among the 782 genes down regulated by the B allele. These results suggest that alterations in SERPINC1 may be implicated in the development of elevated SPAP in patients with CP. Antithrombin III deficiency is a potential factor in chronic thromboembolic pulmonary hypertension, but our results suggest that the putative B polymorphism may have effects beyond the coagulation cascade. Whether this is due to the SERPINC1 polymorphism itself or to another locus in linkage disequilibrium will require our future planned studies, beginning with sequencing of SERPINC1 exon 7 and identification of the polymorphism. Disclosures: No relevant conflicts of interest to declare.


Development ◽  
1993 ◽  
Vol 117 (4) ◽  
pp. 1435-1444 ◽  
Author(s):  
M. Ontell ◽  
M.P. Ontell ◽  
M.M. Sopper ◽  
R. Mallonga ◽  
G. Lyons ◽  
...  

The time course of contractile protein [actin, myosin heavy chain (MHC) and myosin light chain (MLC)] gene expression in the hindlimb muscles of the embryonic mouse (&lt; 15 days gestation) has been correlated with the expression of genes for the myogenic regulatory factors, myogenin and MyoD, and with morphogenetic events. At 14 days gestation, secondary myotubes are not yet present in crural muscles (M. Ontell and K. Kozeka (1984) Am. J. Anat. 171, 133–148; M. Ontell, D. Bourke and D. Hughes (1988) Am. J. Anat. 181, 267–278); therefore, all transcripts for contractile proteins found in these muscles must be produced in primary myotubes. In situ hybridization, with 35S-labeled antisense cRNAs, demonstrates the versatility of primary myotubes in that transcripts for (1) alpha-cardiac and alpha-skeletal actin, (2) MHCembryonic, MHCperinatal and MHC beta/slow, and (3) MLC1A, MLC1F and MLC3F are detectable at 14 days gestation. While the general patterns of early activation of the cardiac genes and early activation of the genes for the developmental isoforms are preserved in both myotomal and limb muscles (D. Sassoon, I. Garner and M. Buckingham (1988) Development 104, 155–164 and G. E. Lyons, M. Ontell, R. Cox, D. Sassoon and M. Buckingham (1990) J. Cell Biol. 111, 1465–1476 for myotomal muscle), there are a number of differences in contractile protein gene expression. For example, in the myotome, when myosin light chain genes are initially transcribed, hybridization signal with probe for MLC1A mRNA is greater than that with probe for MLC1F transcripts, whereas the relative intensity of signal with these same probes is reversed in the hindlimb. The order in which myosin heavy chain genes are activated is also different, with MHCembryonic and MHCperinatal preceding the appearance of MHC beta/slow transcripts in limb muscles, while MHCembryonic and MHC beta/slow appear simultaneously in the myotomes prior to MHCperinatal. In the myotome, an intense hybridization signal for alpha-cardiac and a weak signal for alpha-skeletal actin transcripts are detectable prior to myosin mRNAs, whereas in the limb alpha-cardiac actin transcripts accumulate with myosin transcripts before alpha-skeletal actin mRNA is detectable. These differences indicate that there is no single coordinate pattern of expression of contractile protein genes during initial formation of the muscles of the mouse.(ABSTRACT TRUNCATED AT 400 WORDS)


1981 ◽  
Vol 86 (2) ◽  
pp. 483-492 ◽  
Author(s):  
Moshe Shani ◽  
Dina Zevin-Sonkin ◽  
Ora Saxel ◽  
Yoram Carmon ◽  
Don Katcoff ◽  
...  

1995 ◽  
Vol 269 (1) ◽  
pp. H86-H95 ◽  
Author(s):  
E. Holder ◽  
B. Mitmaker ◽  
L. Alpert ◽  
L. Chalifour

Transgenic mice expressing polyomavirus large T antigen (PVLT) in cardiomyocytes develop a cardiac hypertrophy in adulthood. Morphometric analysis identified cardiomyocytes enlarged up to ninefold in cross-sectional area in the adult transgenic hearts compared with normal age-matched nontransgenic hearts. Most enlarged cardiomyocytes were found in the subendocardium, whereas normal-sized cardiomyocytes were localized to the midmyocardium. Transgenic hearts did not express detectable skeletal muscle actin mRNA or protein, or skeletal troponin I isoform mRNA. Some, but not all, transgenic hearts expressed an increase in the beta-myosin heavy chain mRNA. All five transgenic mice tested had increased expression of atrial natriuretic factor (ANF) mRNA. Whereas normal hearts expressed three myosin light chain proteins of 19, 16, and 15 kDa, we found that the 19-kDa myosin light chain was not observed in the transgenic hearts. We conclude that adult, PVLT-expressing, transgenic mice developed enlarged cardiomyocytes with an increase in beta-myosin heavy chain and ANF mRNA expression, but a widespread skeletal isoform usage was not present in these transgenic mice. The adult transgenic hearts thus display histological and molecular changes similar to those found in hypertrophy induced by a pressure overload in vivo.


1993 ◽  
Vol 25 (5) ◽  
pp. 577-585 ◽  
Author(s):  
T. Trahair ◽  
T. Yeoh ◽  
T. Cartmill ◽  
A. Keogh ◽  
P. Spratt ◽  
...  

1981 ◽  
Vol 195 (1) ◽  
pp. 317-327 ◽  
Author(s):  
O A Young ◽  
C L Davey

A number of single fibres were isolated by dissection of four bovine masseter (ma) muscles, three rectus abdominis (ra) muscles and eight sternomandibularis (sm) muscles. By histochemical criteria these muscles contain respectively, solely slow fibres (often called type I), predominantly fast fibres (type II), and a mixture of fast and slow. The fibres were analysed by conventional sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and the gels stained with Coomassie Blue. Irrespective of the muscle, every fibre could be classed into one of two broad groups based on the mobility of proteins in the range 135000-170000 daltons. When zones containing myosin heavy chain were cut from the single-fibre gel tracks and ‘mapped’ [Cleveland, Fischer, Kirschner & Laemmli (1977) J. Biol. Chem. 252, 1102-1106] with Staphylococcus proteinase, it was found that one group always contained fast myosin heavy chain, whereas the second group always contained the slow form. Moreover, a relatively fast-migrating alpha-tropomyosin was associated with the fast myosin group and a slow-migrating form with the slow myosin group. All fibres also contained beta-tropomyosin; the coexistence of alpha- and beta-tropomyosin is at variance with evidence that alpha-tropomyosin is restricted to fast fibres [Dhoot & Perry (1979) Nature (London) 278, 714-718]. Fast fibres containing the expected fast light chains and troponins I and C fast were identified in the three ra muscles, but in only four sm muscles. In three other sm muscles, all the fast fibres contained two troponins I and an additional myosin light chain that was more typical of myosin light chain 1 slow. The remaining sm muscle contained a fast fibre type that was similar to the first type, except that its myosin light chain 1 was more typical of the slow polymorph. Troponin T was bimorphic in all fast fibres from a ra muscles and in at least some fast fibres from one sm muscle. Peptide ‘mapping’ revealed two forms of fast myosin heavy chain distributed among fast fibres. Each form was associated with certain other proteins. Slow myosin heavy chain was unvarying in three slow fibre types identified. Troponin I polymorphs were the principal indicator of slow fibre types. The myofibrillar polymorphs identified presumably contribute to contraction properties, but beyond cud chewing involving ma muscle, nothing is known of the conditions that gave rise to the variable fibre composites in sm and ra muscles.


2009 ◽  
Vol 297 (4) ◽  
pp. R1037-R1048 ◽  
Author(s):  
Clay E. Pandorf ◽  
Weihua H. Jiang ◽  
Anqi X. Qin ◽  
Paul W. Bodell ◽  
Kenneth M. Baldwin ◽  
...  

The role of calcineurin (Cn) in skeletal muscle fiber-type expression has been a subject of great interest because of reports indicating that it controls the slow muscle phenotype. To delineate the role of Cn in phenotype remodeling, particularly its role in driving expression of the type I myosin heavy chain (MHC) gene, we used a novel strategy whereby a profound transition from fast to slow fiber type is induced and examined in the absence and presence of cyclosporin A (CsA), a Cn inhibitor. To induce the fast-to-slow transition, we first subjected rats to 7 days of hindlimb suspension (HS) + thyroid hormone [triiodothyronine (T3)] to suppress nearly all expression of type I MHC mRNA in the soleus muscle. HS + T3 was then withdrawn, and rats resumed normal ambulation and thyroid state, during which vehicle or CsA (30 mg·kg−1·day−1) was administered for 7 or 14 days. The findings demonstrate that, despite significant inhibition of Cn, pre-mRNA, mRNA, and protein abundance of type I MHC increased markedly during reloading relative to HS + T3 ( P < 0.05). Type I MHC expression was, however, attenuated by CsA compared with vehicle treatment. In addition, type IIa and IIx MHC pre-mRNA, mRNA, and relative protein levels were increased in Cn-treated compared with vehicle-treated rats. These findings indicate that Cn has a modulatory role in MHC transcription, rather than a role as a primary regulator of slow MHC gene expression.


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