scholarly journals Localization of dystrophin gene transcripts during mouse embryogenesis.

1992 ◽  
Vol 119 (4) ◽  
pp. 811-821 ◽  
Author(s):  
D Houzelstein ◽  
G E Lyons ◽  
J Chamberlain ◽  
M E Buckingham
Keyword(s):  
Skeletal Muscle ◽  
Striated Muscle ◽  
Fiber Type ◽  
Endocrine System ◽  
Dystrophin Gene ◽  
Mouse Embryogenesis ◽  
Tissue Sections ◽  
Gene Transcripts ◽  
High Level

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.

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
Keyword(s):  
Skeletal Muscle ◽  
Striated Muscle ◽  
Mouse Muscle ◽  
Embryonic Mouse ◽  
Gene Transcripts ◽  
Specific Mrnas ◽  
Actin Mrna ◽  
Embryo Sections ◽  
Alpha Actin

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.

scholarly journals Tropomodulin isoforms regulate thin filament pointed-end capping and skeletal muscle physiology

2010 ◽  
Vol 189 (1) ◽  
pp. 95-109 ◽  
Author(s):  
David S. Gokhin ◽  
Raymond A. Lewis ◽  
Caroline R. McKeown ◽  
Roberta B. Nowak ◽  
Nancy E. Kim ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Thin Filament ◽  
Striated Muscle ◽  
Fiber Type ◽  
Actin Dynamics ◽  
Muscle Physiology ◽  
Skeletal Muscle Function ◽  
Capping Proteins ◽  
Locomotor Deficits ◽  
End Capping

During myofibril assembly, thin filament lengths are precisely specified to optimize skeletal muscle function. Tropomodulins (Tmods) are capping proteins that specify thin filament lengths by controlling actin dynamics at pointed ends. In this study, we use a genetic targeting approach to explore the effects of deleting Tmod1 from skeletal muscle. Myofibril assembly, skeletal muscle structure, and thin filament lengths are normal in the absence of Tmod1. Tmod4 localizes to thin filament pointed ends in Tmod1-null embryonic muscle, whereas both Tmod3 and -4 localize to pointed ends in Tmod1-null adult muscle. Substitution by Tmod3 and -4 occurs despite their weaker interactions with striated muscle tropomyosins. However, the absence of Tmod1 results in depressed isometric stress production during muscle contraction, systemic locomotor deficits, and a shift to a faster fiber type distribution. Thus, Tmod3 and -4 compensate for the absence of Tmod1 structurally but not functionally. We conclude that Tmod1 is a novel regulator of skeletal muscle physiology.

scholarly journals Multiple regulatory elements contribute differentially to muscle creatine kinase enhancer activity in skeletal and cardiac muscle.

1993 ◽  
Vol 13 (5) ◽  
pp. 2753-2764 ◽  
Author(s):  
S L Amacher ◽  
J N Buskin ◽  
S D Hauschka
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Regulatory Elements ◽  
High Level Expression ◽  
Muscle Creatine Kinase ◽  
Skeletal Myocytes ◽  
E Box ◽  
Nonmuscle Cells ◽  
High Level

We have used transient transfections in MM14 skeletal muscle cells, newborn rat primary ventricular myocardiocytes, and nonmuscle cells to characterize regulatory elements of the mouse muscle creatine kinase (MCK) gene. Deletion analysis of MCK 5'-flanking sequence reveals a striated muscle-specific, positive regulatory region between -1256 and -1020. A 206-bp fragment from this region acts as a skeletal muscle enhancer and confers orientation-dependent activity in myocardiocytes. A 110-bp enhancer subfragment confers high-level expression in skeletal myocytes but is inactive in myocardiocytes, indicating that skeletal and cardiac muscle MCK regulatory sites are distinguishable. To further delineate muscle regulatory sequences, we tested six sites within the MCK enhancer for their functional importance. Mutations at five sites decrease expression in skeletal muscle, cardiac muscle, and nonmuscle cells. Mutations at two of these sites, Left E box and MEF2, cause similar decreases in all three cell types. Mutations at three sites have larger effects in muscle than nonmuscle cells; an A/T-rich site mutation has a pronounced effect in both striated muscle types, mutations at the MEF1 (Right E-box) site are relatively specific to expression in skeletal muscle, and mutations at the CArG site are relatively specific to expression in cardiac muscle. Changes at the AP2 site tend to increase expression in muscle cells but decrease it in nonmuscle cells. In contrast to reports involving cotransfection of 10T1/2 cells with plasmids expressing the myogenic determination factor MyoD, we show that the skeletal myocyte activity of multimerized MEF1 sites is 30-fold lower than that of the 206-bp enhancer. Thus, MyoD binding sites alone are not sufficient for high-level expression in skeletal myocytes containing endogenous levels of MyoD and other myogenic determination factors.

scholarly journals Adiponectin is expressed by skeletal muscle fibers and influences muscle phenotype and function

2008 ◽  
Vol 295 (1) ◽  
pp. C203-C212 ◽  
Author(s):  
Matthew P. Krause ◽  
Ying Liu ◽  
Vivian Vu ◽  
Lawrence Chan ◽  
Aimin Xu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Low Frequency ◽  
Disease States ◽  
L6 Myotubes ◽  
Type Composition ◽  
Low Frequency Fatigue ◽  
And Function

Adiponectin (Ad) is linked to various disease states and mediates antidiabetic and anti-inflammatory effects. While it was originally thought that Ad expression was limited to adipocytes, we demonstrate here that Ad is expressed in mouse skeletal muscles and within differentiated L6 myotubes, as assessed by RT-PCR, Western blot, and immunohistochemical analyses. Serial muscle sections stained for fiber type, lipid content, and Ad revealed that muscle fibers with elevated intramyocellular Ad expression were consistently type IIA and IID fibers with detectably higher intramyocellular lipid (IMCL) content. To determine the effect of Ad on muscle phenotype and function, we used an Ad-null [knockout (KO)] mouse model. Body mass increased significantly in 24-wk-old KO mice [+5.5 ± 3% relative to wild-type mice (WT)], with no change in muscle mass observed. IMCL content was significantly increased (+75.1 ± 25%), whereas epididymal fat mass, although elevated, was not different in the KO mice compared with WT (+35.1 ± 23%; P = 0.16). Fiber-type composition was unaltered, although type IIB fiber area was increased in KO mice (+25.5 ± 6%). In situ muscle stimulation revealed lower peak tetanic forces in KO mice relative to WT (−47.5 ± 6%), with no change in low-frequency fatigue rates. These data demonstrate that the absence of Ad expression causes contractile dysfunction and phenotypical changes in skeletal muscle. Furthermore, we demonstrate that Ad is expressed in skeletal muscle and that its intramyocellular localization is associated with elevated IMCL, particularly in type IIA/D fibers.

scholarly journals PDGFRα Expression During Mouse Embryogenesis: Immunolocalization Analyzed by Whole-mount Immunohistostaining Using the Monoclonal Anti-mouse PDGFRα Antibody APA5

1997 ◽  
Vol 45 (6) ◽  
pp. 883-893 ◽  
Author(s):  
Nobuyuki Takakura ◽  
Hisahiro Yoshida ◽  
Yasunori Ogura ◽  
Hiroshi Kataoka ◽  
Satomi Nishikawa ◽  
...  
Keyword(s):  
Polyclonal Antibodies ◽  
Growth Factor Receptor ◽  
Paraxial Mesoderm ◽  
Mouse Embryogenesis ◽  
Intense Staining ◽  
Tissue Sections ◽  
Whole Mount ◽  
And Migration ◽  
Glial Precursor

We investigated the cells that express platelet-derived growth factor receptor α (PDGFRα) during mouse embryogenesis. PDGFRα expression has been identified by in situ hybridization or immunohistochemistry using polyclonal antibodies on tissue sections. Because no immunostaining study using whole-mount specimens has been published to date, we established a new monoclonal antibody (MAb), APA5, for this purpose. Our results differed in that APA5 stained only the paraxial mesoderm, whereas other investigators concluded that most if not all mesodermal cells expressed PDGFRα. Moreover, we did not find PDGFRα expression in embryonic erythrocytes, which have been previously suggested to express PDGFRα. On the basis of our present results, we wish to revise the proposed PDGFRα expression as follows. At the pregastrulation stage, PDGFRα is expressed only in primitive endoderm, particularly that in the ectoplacental cone. On gastrulation, it is expressed at high levels in the paraxial mesoderm. This expression continues after its differentiation into the somite. Along with the differentiation and migration of the sclerotome, PDGFRα+ cells begin to become distributed throughout the embryonal mesenchyme. During organogenesis, particularly intense staining is detected in regions of epithelial and mesenchymal interaction, such as the tooth bud and bronchi. In addition to mesodermal derivatives, the developing lens, apical ectodermal ridge, glial precursor, cardiac valves, and choroid plexus express PDGFRα. Our results with whole-mount immunostaining show that PDGFRα is abundantly expressed and may play important roles during embryogenesis.

Effects of streptozotocin-induced diabetes and physical training on gene expression of titin-based stretch-sensing complexes in mouse striated muscle

2007 ◽  
Vol 292 (2) ◽  
pp. E533-E542 ◽  
Author(s):  
T. Maarit Lehti ◽  
Mika Silvennoinen ◽  
Riikka Kivelä ◽  
Heikki Kainulainen ◽  
Jyrki Komulainen
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Physical Training ◽  
Striated Muscle ◽  
Fiber Type ◽  
Training Session ◽  
Mrna Levels ◽  
Strain Sensing ◽  
Induced Changes

In striated muscle, a sarcomeric noncontractile protein, titin, is proposed to form the backbone of the stress- and strain-sensing structures. We investigated the effects of diabetes, physical training, and their combination on the gene expression of proteins of putative titin stretch-sensing complexes in skeletal and cardiac muscle. Mice were divided into control (C), training (T), streptozotocin-induced diabetic (D), and diabetic training (DT) groups. Training groups performed for 1, 3, or 5 wk of endurance training on a motor-driven treadmill. Muscle samples from T and DT groups together with respective controls were collected 24 h after the last training session. Gene expression of calf muscles (soleus, gastrocnemius, and plantaris) and cardiac muscle were analyzed using microarray and quantitative PCR. Diabetes induced changes in mRNA expression of the proteins of titin stretch-sensing complexes in Z-disc (MLP, myostatin), I-band (CARP, Ankrd2), and M-line (titin kinase signaling). Training alleviated diabetes-induced changes in most affected mRNA levels in skeletal muscle but only one change in cardiac muscle. In conclusion, we showed diabetes-induced changes in mRNA levels of several fiber-type-biased proteins (MLP, myostatin, Ankrd2) in skeletal muscle. These results are consistent with previous observations of diabetes-induced atrophy leading to slower fiber type composition. The ability of exercise to alleviate diabetes-induced changes may indicate slower transition of fiber type.

Complex fiber-type-specific expression of fast skeletal muscle troponin I gene constructs in transgenic mice

Development ◽  
1993 ◽  
Vol 119 (3) ◽  
pp. 691-701
Author(s):  
P.L. Hallauer ◽  
H.L. Bradshaw ◽  
K.E. Hastings
Keyword(s):  
Skeletal Muscle ◽  
Differential Expression ◽  
Expression Pattern ◽  
Troponin I ◽  
Fiber Type ◽  
Fiber Types ◽  
Fast Skeletal Muscle ◽  
Fast Fiber ◽  
Muscle Gene ◽  
High Level

We analyzed, in transgenic mice, the cellular expression pattern of the quail fast skeletal muscle troponin I (TnIfast) gene and of a chimeric reporter construct in which quail TnIfast DNA sequences drive expression of E. coli beta-galactosidase (beta-gal). Both constructs were actively expressed in skeletal muscle and specifically in fast, as opposed to slow, muscle fibers. Unexpectedly, both constructs showed a marked differential expression among the adult fast fiber subtypes according to the pattern IIB > IIX > IIA. This expression pattern was consistent in multiple lines and differed from the endogenous mouse TnIfast pattern, which shows approximately equal expression in all fast fibers. These observations indicate that distinct regulatory mechanisms contribute to high-level expression of TnIfast in the various fast fiber subtypes and suggest that the outwardly simple pattern of equal expression in all fast fiber types shown by the endogenous mouse TnIfast gene is based on an intricate system of counterbalancing mechanisms. The adult expression pattern of the TnIfast/beta-gal construct emerged in a two-stage developmental process. Differential expression in fast versus slow fibers was evident in neonatal animals, although expression in fast fibers was relatively weak and homogeneous. During the first two weeks of postnatal life, expression in maturing IIB fibers was greatly increased whereas that in IIA/IIX fibers remained weak, giving rise to marked differential expression among fast fiber types. Thus at least two serially acting (pre- and post-natal) fiber-type-specific regulatory mechanisms contribute to high-level gene expression in adult fast muscle fibers. Unexpected similarities between TnIfast transgene expression and that of the myosin heavy chain gene family (which includes differentially expressed IIB-, IIX- and IIA-specific members) suggest that similar mechanisms may regulate adult fast muscle gene expression in a variety of unrelated muscle gene families.

Plasma Triglyceride Metabolism in Humans and Rats during Aging and Physical Inactivity

2001 ◽  
Vol 11 (s1) ◽  
pp. S97-S102 ◽  
Author(s):  
Marc T. Hamilton ◽  
Enas Areiqat ◽  
Deborah G. Hamilton ◽  
Lionel Bey
Keyword(s):  
Skeletal Muscle ◽  
Skeletal Muscles ◽  
Fiber Type ◽  
Weight Bearing ◽  
Aging Effect ◽  
Blood Lipid ◽  
Plasma Triglyceride ◽  
Blood Lipid Profile ◽  
Triglyceride Metabolism ◽  
High Level

Physical activity often declines with age because of a reduction in the spontaneous activities of daily living and because of less intense exercise. In controlled studies of young rats, it was shown that physical activities associated with walking and standing were especially important for maintaining a high level of lipoprotein lipase (LPL) activity in postural skeletal muscles (slowtwitch oxidative muscles). More intense contractions during run training were important for a high LPL activity in the fast-twitch glycolytic muscles. Aging also causes a fiber type–specific decrease of skeletal muscle LPL activity and LPL protein in weight-bearing skeletal muscles (and no aging effect in glycolytic muscles). Thus, contractile inactivity may be a significant factor causing sub-optimal triglyceride metabolism in skeletal muscles during both unloading in young animals and aging. Measurements of plasma LPL activity, plasma triglyceride (TG) clearance rates, postprandial hypertriglyceridemia after oral fat tolerance tests, and fasting TG levels were generally indicative of reduced plasma TG metabolism during middle or old age. In contrast, older endurance-trained individuals had a favorable blood lipid profile compared to age-matched or young controls, even when the controls were not overweight. Therefore, the poor TG metabolism that is frequently associated with aging may be caused by some of the same processes that lower skeletal muscle LPL activity of young sedentary individuals.

Acute effect of L-carnitine on skeletal muscle force tests in dogs

1991 ◽  
Vol 260 (2) ◽  
pp. E189-E193 ◽  
Author(s):  
M. L. Dubelaar ◽  
C. M. Lucas ◽  
W. C. Hulsmann
Keyword(s):  
Skeletal Muscle ◽  
Muscle Force ◽  
Striated Muscle ◽  
Acute Effect ◽  
Acid Oxidation ◽  
Structural Analogue ◽  
Carnitine Transport ◽  
Musculus Latissimus Dorsi ◽  
Positive Effect

Using the mixed type musculus latissimus dorsi of the dog in the present work, we show the effect of carnitine on an in situ fatigue test. L-Carnitine appears to improve force of this muscle by 34% while stimulated in situ. This effect of carnitine is acute and (stereo)specific, since neither D-carnitine nor the structural analogue choline (also a tertiary amine) has a positive effect on contractile force. Because skeletal muscle is rich in carnitine and because carnitine transport is slow, its effect must be exerted outside the striated muscle cells. Insulin (with glucose) administration abolished the carnitine effect. It is speculated that facilitation of fatty acid oxidation in the blood vessel wall is the basis for this positive effect of carnitine.

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