alpha-Actin proteins and gene transcripts are colocalized in embryonic mouse muscle

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 451-454 ◽  
Author(s):  
G.E. Lyons ◽  
M.E. Buckingham ◽  
H.G. Mannherz

The alpha-actins are among the earliest muscle-specific mRNAs to appear in developing cardiac and skeletal muscle. To determine if there is coexpression of the alpha-actin proteins at early stages of myogenesis, we have used an alpha-actin-specific polyclonal antibody and in situ hybridization with specific cRNA probes to cardiac and skeletal alpha-actin transcripts on serial slides of mouse embryo sections. As soon as we can detect alpha-actin mRNAs in embryonic striated muscle, we also detect the protein suggesting that alpha-actin transcripts are translated very rapidly after transcription during myogenesis. In skeletal muscle, this colocalization of alpha-actin mRNA and protein was observed both in the myotomes of somites and in developing muscles in the limbs. In cardiac muscle, alpha-actin transcripts and proteins are abundantly expressed as soon as a cardiac tube forms.

1992 ◽  
Vol 119 (4) ◽  
pp. 811-821 ◽  
Author(s):  
D Houzelstein ◽  
G E Lyons ◽  
J Chamberlain ◽  
M E Buckingham

The spatial and temporal expression of the dystrophin gene has been examined during mouse embryogenesis, using in situ hybridization on tissue sections with a probe from the 5' end of the dystrophin coding sequence. In striated muscle, dystrophin transcripts are detectable from about 9 d in the heart and slightly later in skeletal muscle. However, there is an important difference between the two types of muscle: the heart is already functional as a contractile organ before the appearance of dystrophin transcripts, whereas this is not the case in skeletal muscle, where dystrophin and myosin heavy chain transcripts are first detectable at the same time. In the heart, dystrophin transcripts accumulate initially in the outflow tract and, at later stages, in both the atria and ventricles. In skeletal muscle, the gene is expressed in all myocytes irrespective of fiber type. In smooth muscle dystrophin transcripts are first detectable from 11 d post coitum in blood vessels, and subsequently in lung bronchi and in the digestive tract. The other major tissue where the dystrophin gene is expressed is the brain, where transcripts are clearly detectable in the cerebellum from 13 d. High-level expression of the gene is also seen in particular regions of the forebrain involved in the regulation of circadian rhythms, the endocrine system, and olfactory function, not previously identified in this context. The findings are discussed in the context of the pathology of Duchenne muscular dystrophy.


1988 ◽  
Vol 254 (5) ◽  
pp. C657-C660 ◽  
Author(s):  
P. Babij ◽  
F. W. Booth

It is known that denervation or hindlimb suspension both decrease the content of rRNA, alpha-actin mRNA, and cytochrome c mRNA in adult rat skeletal muscle. In the present study, the provision of clenbuterol (an anabolic agent) to adult female rats during a 7-day period of denervation of the soleus and gastrocnemius muscles prevented entirely the loss of rRNA, alpha-actin mRNA, and cytochrome c mRNA that normally occurs in denervated muscle. Although clenbuterol inhibited most of the loss of alpha-actin mRNA that occurred in the soleus and gastrocnemius muscles after 7 days of hindlimb suspension, clenbuterol administration had less effect on preventing the loss of rRNA and cytochrome c mRNA in hindlimb suspended skeletal muscle. Clenbuterol had no effect on protein content in atrophied muscle resulting from denervation or suspension. These data suggest that clenbuterol can maintain the expression of certain RNAs in atrophying adult rat skeletal muscle.


1989 ◽  
Vol 9 (9) ◽  
pp. 3785-3792
Author(s):  
C J Petropoulos ◽  
M P Rosenberg ◽  
N A Jenkins ◽  
N G Copeland ◽  
S H Hughes

We have generated transgenic mouse lines that carry the promoter region of the chicken skeletal muscle alpha (alpha sk) actin gene linked to the bacterial chloramphenicol acetyltransferase (CAT) gene. In adult mice, the pattern of transgene expression resembled that of the endogenous alpha sk actin gene. In most of the transgenic lines, high levels of CAT activity were detected in striated muscle (skeletal and cardiac) but not in the other tissues tested. In striated muscle, transcription of the transgene was initiated at the normal transcriptional start site of the chicken alpha sk actin gene. The region from nucleotides -191 to +27 of the chicken alpha sk actin gene was sufficient to direct the expression of CAT in striated muscle of transgenic mice. These observations suggest that the mechanism of tissue-specific actin gene expression is well conserved in higher vertebrate species.


Development ◽  
1993 ◽  
Vol 117 (4) ◽  
pp. 1409-1420 ◽  
Author(s):  
R. Moore ◽  
F.S. Walsh

The spatiotemporal distribution of M-cadherin mRNA has been determined by in situ hybridization in the mouse embryo and in adult skeletal muscle following experimental regeneration and denervation. M-cadherin mRNA is highly tissue specific and is found only in developing skeletal muscle. In contrast, N-cadherin mRNA has a broader tissue distribution in the embryo, being found on both neural elements and skeletal and cardiac muscle. M-cadherin is expressed in the myotomes shortly after they form, along with the myogenic regulatory factor myogenin. M-cadherin is expressed in muscles derived from the myotomes and is detected in forelimb bud precursor cells at embryonic day 11.5. In the latter case M-cadherin expression appears co-ordinately with that of myogenin and cardiac alpha-actin. Shortly before birth, M-cadherin expression is down regulated. M-cadherin can, however, be re-expressed following experimental regeneration of skeletal muscle. Here M-cadherin is transiently expressed on regenerating myoblasts but not myotubes. Following muscle denervation no evidence was found for re-expression of M-cadherin under conditions where there was strong expression of the nicotinic acetylcholine receptor on myofibres. The highly specific tissue distribution and unique developmental profile distinguishes M-cadherin from other cadherins and suggests a role in cell surface events during early myogenesis.


1989 ◽  
Vol 66 (3) ◽  
pp. 1093-1098 ◽  
Author(s):  
G. Howard ◽  
J. M. Steffen ◽  
T. E. Geoghegan

Muscle atrophy resulting from disuse is associated with marked decrements in protein synthesis. The objective of the present investigation was to determine levels of total muscle RNA and the content and composition of the mRNA fraction as a qualitative assessment of the potential regulatory role of transcriptional alterations in unloaded skeletal muscles. Hindlimb muscle unloading was produced by whole-body suspension of rats for up to 7 days. The soleus, gastrocnemius, and extensor digitorum longus (EDL) were excised from 1-, 3-, and 7-day suspended and pair-fed controls, and RNA was extracted by homogenization in 5 M guanidinium thiocyanate. Total RNA and mRNA contents were lower in soleus and gastrocnemius after 7 days of suspension compared with pair-fed controls, but total RNA and mRNA concentrations (per g muscle and per microgram total RNA, respectively) were unaltered. alpha-Actin mRNA, assessed by dot blot hybridization, was significantly reduced in soleus after 1 (37%), 3 (28%), and 7 (59%) days of suspension and in gastrocnemius after 3 (44%) and 7 (41%) days. However, alpha-actin mRNA was unchanged in the EDL after suspension. Protein synthesis directed by RNA extracted from soleus and EDL indicated marked (30–400%) alterations in mRNAs coding for several small (15- to 25-kDa) proteins. The results of this study suggest that altered transcription and availability of specific mRNAs could contribute significantly to the regulation of protein synthesis during unloading of skeletal muscle.


1989 ◽  
Vol 9 (9) ◽  
pp. 3785-3792 ◽  
Author(s):  
C J Petropoulos ◽  
M P Rosenberg ◽  
N A Jenkins ◽  
N G Copeland ◽  
S H Hughes

We have generated transgenic mouse lines that carry the promoter region of the chicken skeletal muscle alpha (alpha sk) actin gene linked to the bacterial chloramphenicol acetyltransferase (CAT) gene. In adult mice, the pattern of transgene expression resembled that of the endogenous alpha sk actin gene. In most of the transgenic lines, high levels of CAT activity were detected in striated muscle (skeletal and cardiac) but not in the other tissues tested. In striated muscle, transcription of the transgene was initiated at the normal transcriptional start site of the chicken alpha sk actin gene. The region from nucleotides -191 to +27 of the chicken alpha sk actin gene was sufficient to direct the expression of CAT in striated muscle of transgenic mice. These observations suggest that the mechanism of tissue-specific actin gene expression is well conserved in higher vertebrate species.


Development ◽  
1991 ◽  
Vol 113 (3) ◽  
pp. 1017-1029 ◽  
Author(s):  
G.E. Lyons ◽  
S. Muhlebach ◽  
A. Moser ◽  
R. Masood ◽  
B.M. Paterson ◽  
...  

The B isoform of creatine kinase (BCK), which is expressed at a high level in embryonic neural tissues, is also expressed abundantly in developing striated muscle and is an early marker for skeletal myogenesis. Using isoform-specific 35S-labeled antisense cRNA probes for in situ hybridization, we have detected BCK mRNAs in embryonic mouse and chick myotomes, the first skeletal muscle masses to form in developing embryos. These transcripts are detectable as soon as myotomes are morphologically distinguishable. BCK is expressed at high levels in both skeletal and cardiac muscle in mouse and chick embryos. In the mouse, BCK transcript levels fall of rapidly in striated muscle shortly after the onset of MCK gene expression. The M isoform of creatine kinase (MCK), the striated muscle-specific isoform, is expressed later than BCK. In the mouse, BCK transcripts are expressed in myotomes at 8.5 days post coitum (p.c.), but MCK transcripts are not detected before 13 days p.c. In the chick, BCK mRNAs are present at Hamburger-Hamilton stage 13, but MCK mRNAs are not detected before stage 19. We have compared the patterns of expression of the CK genes with those of myogenic differentiation factor genes, which are thought to regulate skeletal muscle-specific gene expression. In the chick, both CMD1, first detected at stage 13, and myogenin, first detected at stage 15, are present prior to MCK, which begins to be expressed at stage 19. Unlike the mouse embryo, CMD1, the chick homologue of MyoD1, is expressed before chick myogenin. In the mouse, myogenin, first detected at 8.5 days p.c., is expressed at the same time as BCK in myotomes. Both myogenin and MyoD1, which begins to be detected two days later than myogenin, are expressed at least two days before MCK. It has been proposed that the myogenic factors, MyoD1 and myogenin, directly regulate MCK gene expression in the mouse by binding to its enhancer. However, our results show that MCK transcripts are not detected until well after MyoD1 and myogenin mRNAs are expressed, suggesting that these factors by themselves are not sufficient to initiate MCK gene expression.


1992 ◽  
Vol 73 (2) ◽  
pp. S90-S93 ◽  
Author(s):  
D. B. Thomason ◽  
P. R. Morrison ◽  
V. Oganov ◽  
E. Ilyina-Kakueva ◽  
F. W. Booth ◽  
...  

The mechanism for cardiovascular deconditioning and skeletal muscle atrophy during microgravity is not known. The purpose of the present study was to determine whether a decrease in contractile protein gene expression in the muscle of rats occurred after 14 days of microgravity. No differences existed in the profile of myosin protein isoforms or beta-myosin heavy chain mRNA in hearts between the flight and synchronous control groups. On the other hand, differences in the expression of beta-myosin heavy chain mRNA relative to the 18S and 28S rRNA in the heart between flight and synchronous control groups were noted with a covariance mapping analysis. Both the vastus intermedius and lateral gastrocnemius muscles exhibited significant (P less than 0.05) decreases in skeletal alpha-actin mRNA per unit of extractable RNA in the flight group compared with the synchronous control group. However, no significant difference for skeletal alpha-actin mRNA occurred in the triceps brachii muscle between these groups. Cytochrome c mRNA per unit of extractable RNA decreased (P less than 0.05) only in the vastus intermedius but not in the lateral gastrocnemius or triceps brachii muscles. In summary, changes in the pretranslational regulation of contractile protein gene expression occur in both heart and skeletal muscle after 14 days of microgravity.


1986 ◽  
Vol 6 (9) ◽  
pp. 3287-3290
Author(s):  
R Hickey ◽  
A Skoultchi ◽  
P Gunning ◽  
L Kedes

The rat myogenic cell line L6E9 induces skeletal but not cardiac alpha-actin mRNA upon fusion to form myotubes. However, when a human cardiac alpha-actin gene was introduced into L6E9 myoblasts, differentiation of the cells led to the accumulation of human gene transcripts in parallel with those derived from the endogenous skeletal alpha-actin gene. This result demonstrates that factors which direct rat myogenesis can regulate a muscle gene from another species and that the L6E9 cells may have a defect in their ability to activate endogenous cardiac actin gene expression.


2017 ◽  
Vol 312 (3) ◽  
pp. C209-C221 ◽  
Author(s):  
Adel Amirouche ◽  
Vanessa E. Jahnke ◽  
John A. Lunde ◽  
Nathalie Koulmann ◽  
Damien G. Freyssenet ◽  
...  

Over the last several years, converging lines of evidence have indicated that miR-206 plays a pivotal role in promoting muscle differentiation and regeneration, thereby potentially impacting positively on the progression of neuromuscular disorders, including Duchenne muscular dystrophy (DMD). Despite several studies showing the regulatory function of miR-206 on target mRNAs in skeletal muscle cells, the effects of overexpression of miR-206 in dystrophic muscles remain to be established. Here, we found that miR-206 overexpression in mdx mouse muscles simultaneously targets multiple mRNAs and proteins implicated in satellite cell differentiation, muscle regeneration, and at the neuromuscular junction. Overexpression of miR-206 also increased the levels of several muscle-specific mRNAs/proteins, while enhancing utrophin A expression at the sarcolemma. Finally, we also observed that the increased expression of miR-206 in dystrophin-deficient mouse muscle decreased the production of proinflammatory cytokines and infiltration of macrophages. Taken together, our results show that miR-206 acts as a pleiotropic regulator that targets multiple key mRNAs and proteins expected to provide beneficial adaptations in dystrophic muscle, thus highlighting its therapeutic potential for DMD.


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