Induction of beta-MHC transgene in overloaded skeletal muscle is not eliminated by mutation of conserved elements

1996 ◽  
Vol 271 (2) ◽  
pp. C690-C699 ◽  
Author(s):  
G. L. Tsika ◽  
J. L. Wiedenman ◽  
L. Gao ◽  
J. J. McCarthy ◽  
K. Sheriff-Carter ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Specific Activity ◽  
Fold Increase ◽  
Histochemical Staining ◽  
Type I ◽  
Plantaris Muscle ◽  
Mechanical Overload ◽  
Type I Fibers ◽  
Fast Twitch ◽  
Cat Expression

Mechanical overload leads to hypertrophy, increased type I fiber composition, and beta-myosin heavy chain (beta-MHC) induction in the fast-twitch plantaris muscle. To better understand the mechanism(s) involved in beta-MHC induction, we have examined inducible expression of transgenes carrying the simultaneous mutation of three DNA regulatory subregions [muscle CAT (MCAT), C-rich, and beta e3] in the context of either 5,600-base pair (bp; beta 5.6mut3) or 600-bp (beta 0.6mut3) beta-MHC promoter in overloaded plantaris muscles of transgenic mice. Protein extract from mechanically overloaded plantaris muscle of mice, harboring either mutant transgene beta 5.6mut3 or beta 0.6mut3, showed an unexpected 2.8- to 4.5-fold increase in chloramphenicol acetyltransferase (CAT) specific activity relative to their respective controls. Similar results were obtained with wild-type (wt) beta-MHC transgenes (beta 5.6wt, beta 0.6wt). Histochemical staining for both myofibrillar ATPase and CAT activity and CAT immunohistochemistry revealed a striking increase in type I fibers and that CAT expression was restricted to these fibers in overloaded plantaris muscle of beta 5.6mut3 transgenic mice. Our transgenic data suggest that beta-MHC transgenes, and perhaps the endogenous beta-MHC gene, are induced by mechanical overload via a mechanism(s) that does not exclusively require the MCAT, C-rich, or beta e3 subregions.

Muscle-specific and inducible expression of 293-base pair beta-myosin heavy chain promoter in transgenic mice

1996 ◽  
Vol 271 (3) ◽  
pp. R688-R695 ◽  
Author(s):  
J. L. Wiedenman ◽  
G. L. Tsika ◽  
L. Gao ◽  
J. J. McCarthy ◽  
I. D. Rivera-Rivera ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Specific Activity ◽  
Fiber Type ◽  
Regulatory Element ◽  
Histochemical Staining ◽  
Regulatory Sequences ◽  
Type I ◽  
Adult Mice ◽  
Mechanical Overload

The DNA regulatory element(s) involved in beta-myosin heavy chain (beta-MHC) induction by the physiological stimulus of mechanical overload have not been identified as yet. To delineate regulatory sequences that are required for mechanical overload induction of the beta-MHC gene, transgenic mouse lines were generated that harbor transgenes containing serial deletions of the human beta-MHC promoter to nucleotides -293 (beta 293), -201 (beta 201), and -141 (beta 141) from the transcription start site (+1). Mechanically overloaded adult plantaris and soleus muscles contained 11- and 1.9-fold increases, respectively, in endogenous beta-MHC-specific mRNA transcripts (Northern blot) compared with sham-operated controls. Expression assays (chloramphenicol acetyltransferase specific activity) revealed that only transgene beta 293 expression was muscle specific in both fetal and adult mice and was induced in the plantaris (10- to 27-fold) and soleus (2- to 2.5-fold) muscles by mechanical overload. Histochemical staining for myosin adenosinetriphosphatase activity revealed a fiber-type transition of type II to type I in the overloaded plantaris and soleus muscles. These transgenic data suggest that sequences located between nucleotides -293 and +120 may be sufficient to regulate the endogenous beta-MHC gene in response to developmental signals and to the physiological signals generated by mechanical overload in fast- and slow-twitch muscles.

Glucocorticoid-induced muscle atrophy prevention by exercise in fast-twitch fibers

1990 ◽  
Vol 69 (3) ◽  
pp. 1058-1062 ◽  
Author(s):  
M. T. Falduto ◽  
S. M. Czerwinski ◽  
R. C. Hickson
Keyword(s):  
Muscle Atrophy ◽  
Fiber Type ◽  
Histochemical Staining ◽  
Female Rats ◽  
Type I ◽  
Type Ii ◽  
Plantaris Muscle ◽  
Exercise Regimen ◽  
Deep Region ◽  
Fast Twitch

Exercise has been shown to be effective in preventing glucocorticoid-induced atrophy in muscles containing high proportions of type II or fast-twitch fibers. This investigation was undertaken to further evaluate this response in type IIa and IIb fibers, determined by histochemical staining for myofibrillar adenosinetriphosphatase with alkaline and acid preincubation. Steroid [cortisol acetate (CA), 100 mg/kg body wt] and exercise (running 90 min/day, 29 m/min) treatments were initiated simultaneously for 11 consecutive days in female rats. Fiber distribution and area measurements were performed in a deep and superficial region of plantaris muscle. The exercise regimen spared approximately 40% of the CA-induced plantaris muscle atrophy. In the deep region, the fiber population, which contained approximately 13% type I (slow-twitch), 24% type IIa, and 63% IIb fibers, was not affected by either treatment. In the superficial section, which consisted solely of type II fibers, the proportion of type IIa fibers was higher (27 vs. 9%, P less than 0.01) in the steroid- than in the vehicle-treated groups. Within each region, type IIa fibers were less susceptible to atrophy than type IIb fibers, and within each fiber type, the deep region had less atrophy than the superficial region. Type I fibers were unchanged by steroid treatment. For type IIa fibers, exercise prevented 100% of the atrophy in the deep region and 50% in the superficial region. For type IIb fibers, the activity spared 67 and 40% of the atrophy in these same regions, respectively. These results show that glucocorticoids are capable of changing the myosin phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Adrenergic control of vascular resistance varies in muscles composed of different fiber types: influence of the vascular endothelium

2011 ◽  
Vol 301 (3) ◽  
pp. R783-R790 ◽  
Author(s):  
Bradley J. Behnke ◽  
Robert B. Armstrong ◽  
Michael D. Delp
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Vascular Endothelium ◽  
Fold Increase ◽  
Male Rats ◽  
Type I ◽  
Fiber Types ◽  
Fast Twitch Muscle ◽  
Dose Responses ◽  
Fast Twitch

The influence of the sympathetic nervous system (SNS) upon vascular resistance is more profound in muscles comprised predominately of low-oxidative type IIB vs. high-oxidative type I fiber types. However, within muscles containing high-oxidative type IIA and IIX fibers, the role of the SNS on vasomotor tone is not well established. The purpose of this study was to examine the influence of sympathetic neural vasoconstrictor tone in muscles composed of different fiber types. In adult male rats, blood flow to the red and white portions of the gastrocnemius (GastRed and GastWhite, respectively) and the soleus muscle was measured pre- and postdenervation. Resistance arterioles from these muscles were removed, and dose responses to α1-phenylephrine or α2-clonidine adrenoreceptor agonists were determined with and without the vascular endothelium. Denervation resulted in a 2.7-fold increase in blood flow to the soleus and GastRed and an 8.7-fold increase in flow to the GastWhite. In isolated arterioles, α2-mediated vasoconstriction was greatest in GastWhite (∼50%) and less in GastRed (∼31%) and soleus (∼17%); differences among arterioles were abolished with the removal of the endothelium. There was greater sensitivity to α1-mediated vasoconstriction in the GastWhite and GastRed vs. the soleus, which was independent of whether the endothelium was present. These data indicate that 1) control of vascular resistance by the SNS in high-oxidative, fast-twitch muscle is intermediate to that of low-oxidative, fast-twitch and high-oxidative, slow-twitch muscles; and 2) the ability of the SNS to control blood flow to low-oxidative type IIB muscle appears to be mediated through postsynaptic α1- and α2-adrenoreceptors on the vascular smooth muscle.

Beta-MHC and SMLC1 transgene induction in overloaded skeletal muscle of transgenic mice

1996 ◽  
Vol 270 (4) ◽  
pp. C1111-C1121 ◽  
Author(s):  
J. L. Wiedenman ◽  
I. Rivera-Rivera ◽  
D. Vyas ◽  
G. Tsika ◽  
L. Gao ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Troponin C ◽  
Type I ◽  
Initial Attempt ◽  
Specific Expression ◽  
Slow Type ◽  
Transgenic Lines ◽  
Fast Twitch Muscle ◽  
Mechanical Overload

The hypertrophic responses of white fast-twitch muscle to mechanical overload has been investigated using transgenic mice. After 7 wk of overload, endogenous beta-myosin heavy chain (MHC) and slow myosin light chain 1 and 2 (SMLC1, SMLC2) protein were increased in the overloaded plantaris (OP) muscle compared with sham-operated control plantaris (CP)muscle. Concurrently, the levels of endogenous beta-MHC, SMLC1, SMLC2, and cardiac/slow troponin C (CTnC) mRNA transcripts were significantly increased in OP muscles, whereas skeletal troponin C (sTnC) mRNA transcript levels decreased. As an initial attempt to locate DNA sequence(s) that governs beta-MHC induction in response to mechanical overload, multiple independent transgenic lines harboring four different human beta-MHC transgenes (beta 1286, beta 988, beta 450, beta 141) were generated. Except for transgene beta 141, muscle-specific expression and induction (3- to 22-fold) in OP muscles were observed by measuring chloramphenicol acetyltransferase activity (CAT assay). Induction of a SMLC1 transgene (3920SMLC1) in OP muscles was also observed. Collectively, these in vivo data provide evidence that 1) a mechanical overload inducible element(s) is located between nucleotides -450 and +120 of the human beta-MHC transgene, 2) 3,900 bp of 5' sequence is sufficient to confer mechanical overload induction of a SMLC1 transgene, and 3) the increased expression of slow/type I isomyosin (beta-MHC, SMLC1, SMLC2) in response to mechanical overload is regulated, in part, transcriptionally.

beta-MHC transgene expression in suspended and mechanically overloaded/suspended soleus muscle of transgenic mice

1997 ◽  
Vol 272 (5) ◽  
pp. R1552-R1561 ◽  
Author(s):  
J. J. McCarthy ◽  
A. M. Fox ◽  
G. L. Tsika ◽  
L. Gao ◽  
R. W. Tsika
Keyword(s):  
Transgenic Mice ◽  
Soleus Muscle ◽  
Transgene Expression ◽  
Specific Activity ◽  
Fiber Type ◽  
Weight Bearing ◽  
Troponin C ◽  
Hindlimb Suspension ◽  
Regulatory Sequences ◽  
Type I

Non-weight-bearing (NWB) activity [space flight and hindlimb suspension (HS)] results in the loss of soleus muscle mass, a slow-to-fast fiber-type conversion, and decreased beta-myosin heavy chain (beta-MHC) protein and mRNA expression. To identify beta-MHC promoter sequences required for decreased beta-MHC expression in response to HS, we have modified an existing noninvasive hindlimb unweighting model to accommodate the use of (transgenic) mice. After 2 wk of HS, body and muscle (soleus > gastrocnemius > plantaris) weights were decreased as was the proportion of histochemically classified type I fibers in HS soleus muscle. Northern blot analysis revealed decreases in endogenous mRNA representing beta-MHC, slow myosin light chain 1 and 2, and cardiac/slow troponin C, whereas those representing skeletal troponin C, muscle creatine kinase, and glyceraldehyde-3-phosphate dehydrogenase increased. Protein extracts prepared from HS soleus (SS) muscle of mice harboring transgenes comprised of 5.6 or 0.6 kilobase of wild type (wt) mouse beta-MHC promoter (beta 5.6 wt, beta 0.6wt) and those carrying the simultaneous mutation (mut) of the MCAT, C-rich, and beta e3 subregions (beta 5.6mut3, beta 0.6mut3) revealed decreases in chloramphenicol acetyltransferase (CAT) specific activity relative to respective controls. Decreased CAT mRNA was observed for transgene beta 5.6mut3, line 85. Two weeks of the simultaneous imposition of mechanical overload (synergist ablation) and HS (MOV/HS) countermanded the loss in absolute and normalized SS weight but did not decrease beta 0.6wt transgene expression. These transgenic results demonstrate that regulatory sequences within a 600-base pair beta-MHC promoter are sufficient to direct decreased transcription of beta-MHC transgenes after 2 wk of HS.

scholarly journals Glucocorticoids stimulate collagen and noncollagen protein synthesis in cultured vascular smooth muscle cells.

1984 ◽  
Vol 98 (2) ◽  
pp. 541-549 ◽  
Author(s):  
D C Leitman ◽  
S C Benson ◽  
L K Johnson
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Specific Activity ◽  
Fold Increase ◽  
Muscle Cells ◽  
Type I ◽  
Twofold Increase ◽  
In Cells

The effect of glucocorticoids on collagen synthesis was examined in cultured bovine aortic smooth muscle (BASM) cells. BASM cells treated with 0.1 microM dexamethasone during their proliferative phase (11 d) were labeled with [3H]proline for 24 h, and the acid-precipitable material was incubated with bacterial collagenase. Dexamethasone produced an approximate twofold increase in the incorporation of proline into collagenase-digestible protein (CDP) and noncollagen protein (NCP) in the cell layer and medium. The stimulation was present in both primary mass cultures and cloned BASM. An increase in CDP and NCP was detected at 0.1 nM, while maximal stimulation occurred at 0.1 microM. Only cells exposed to dexamethasone during their log phase of growth (1-6 d after plating) showed the increase in CDP and NCP when labeled 11 d after plating. The stimulatory effect was observed in BASM cells treated with the natural bovine glucocorticoid, cortisol, dexamethasone, and testosterone, but was absent in cells treated with aldosterone, corticosterone, cholesterol, 17 beta-estradiol, and progesterone. The increase in CDP and NCP was absent in cells treated with the inactive glucocorticoid, epicortisol, and totally abolished by the antagonist, 17 alpha-hydroxyprogesterone, suggesting that the response was mediated by specific cytoplasmic glucocorticoid receptors. Dexamethasone-treated BASM cells showed a 4.5-fold increase in the specific activity of intracellular proline, which was the result of a twofold increase in the uptake of proline and depletion of the total proline pool. After normalizing for specific activity, dexamethasone produced a 2.4- and 2.8-fold increase in the rate of collagen and NCP synthesis, respectively. Cells treated with dexamethasone secreted 1.7-fold more collagen protein in 24 h compared to control cultures. The BASM cells secreted 70% Type I and 30% Type III collagen into the media as assessed by two-dimensional gel electrophoresis. The ratio of these two types was not altered by dexamethasone. The results of the present study demonstrate that glucocorticoids can act directly on vascular smooth muscle cells to increase the synthesis and secretion of collagen and NCP.

Effect of hypothyroidism on myosin heavy chain expression in rat pharyngeal dilator muscles

1992 ◽  
Vol 73 (1) ◽  
pp. 179-187 ◽  
Author(s):  
B. J. Petrof ◽  
A. M. Kelly ◽  
N. A. Rubinstein ◽  
A. I. Pack
Keyword(s):  
Thyroid Hormone ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Hormone Deficiency ◽  
Type I ◽  
Type Ii ◽  
Airway Patency ◽  
Obstructive Sleep ◽  
Type I Fibers ◽  
Fast Twitch

Although the association between hypothyroidism and obstructive sleep apnea is well established, the effect of thyroid hormone deficiency on contractile proteins in pharyngeal dilator muscles responsible for maintaining upper airway patency is unknown. In the present study, the effects of hypothyroidism on myosin heavy chain (MHC) expression were examined in the sternohyoid, geniohyoid, and genioglossus muscles of adult rats (n = 20). The relative proportions of MHC isoforms present were determined using MHC-specific monoclonal antibodies and oligonucleotide probes. All control muscles showed a paucity of type I MHC fibers, with greater than 90% of fibers containing fast-twitch type II MHCs. In the genioglossus muscle, a population of non-IIa non-IIb fast-twitch type II fibers (putatively identified as type IIx MHC fibers) were detected. Hypothyroidism induced significant changes in MHC expression in all muscles studied. In the sternohyoid, type I fibers increased from 6.2 to 16.9%, whereas type IIa fibers increased from 25.9 to 30.7%. Type I fibers in the geniohyoid increased from 1.2 to 12.8%, whereas type IIa fibers increased from 34.1 to 42.7%. The genioglossus showed the smallest relative increase in type I expression but the greatest induction of type IIa MHC. None of the muscles examined demonstrated reinduction of embryonic or neonatal MHC in response to thyroid hormone deficiency. In summary, hypothyroidism alters the MHC profile of pharyngeal dilators in a muscle-specific manner. These changes may play a role in the pathogenesis of obstructive apnea in hypothyroid patients.

scholarly journals Myosin content of individual human muscle fibers isolated by laser capture microdissection

2016 ◽  
Vol 310 (5) ◽  
pp. C381-C389 ◽  
Author(s):  
Charles A. Stuart ◽  
William L. Stone ◽  
Mary E. A. Howell ◽  
Marianne F. Brannon ◽  
H. Kenton Hall ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Type I ◽  
Fiber Types ◽  
Myosin Heavy Chains ◽  
Heavy Chains ◽  
Slow Twitch ◽  
Type I Fibers ◽  
Fast Twitch ◽  
Laser Capture

Muscle fiber composition correlates with insulin resistance, and exercise training can increase slow-twitch (type I) fibers and, thereby, mitigate diabetes risk. Human skeletal muscle is made up of three distinct fiber types, but muscle contains many more isoforms of myosin heavy and light chains, which are coded by 15 and 11 different genes, respectively. Laser capture microdissection techniques allow assessment of mRNA and protein content in individual fibers. We found that specific human fiber types contain different mixtures of myosin heavy and light chains. Fast-twitch (type IIx) fibers consistently contained myosin heavy chains 1, 2, and 4 and myosin light chain 1. Type I fibers always contained myosin heavy chains 6 and 7 (MYH6 and MYH7) and myosin light chain 3 (MYL3), whereas MYH6, MYH7, and MYL3 were nearly absent from type IIx fibers. In contrast to cardiomyocytes, where MYH6 (also known as α-myosin heavy chain) is seen solely in fast-twitch cells, only slow-twitch fibers of skeletal muscle contained MYH6. Classical fast myosin heavy chains (MHC1, MHC2, and MHC4) were present in variable proportions in all fiber types, but significant MYH6 and MYH7 expression indicated slow-twitch phenotype, and the absence of these two isoforms determined a fast-twitch phenotype. The mixed myosin heavy and light chain content of type IIa fibers was consistent with its role as a transition between fast and slow phenotypes. These new observations suggest that the presence or absence of MYH6 and MYH7 proteins dictates the slow- or fast-twitch phenotype in skeletal muscle.

Oxidative potential in developing rat diaphragm, EDL, and soleus muscle fibers

1988 ◽  
Vol 254 (5) ◽  
pp. C661-C668 ◽  
Author(s):  
D. Smith ◽  
H. Green ◽  
J. Thomson ◽  
M. Sharratt
Keyword(s):  
Type I ◽  
Fiber Types ◽  
Rat Diaphragm ◽  
Oxidative Potential ◽  
A Value ◽  
Male Wistar Rats ◽  
Edl Muscle ◽  
Type I Fibers ◽  
Fast Twitch ◽  
Developing Rat

To examine the effect of postnatal development on changes in oxidative potential of fibers of specific types (I, IIa, IIb, and IIc) in the rat diaphragm, determinations of succinate dehydrogenase (SDH) activity were made using microphotometric measures of optical density. Samples of the costal region of the diaphragm were extracted from 56 male Wistar rats ranging in age from 8 to 85 days and subgrouped into seven developmental periods (1, 2, 3, 4, 6, 9, and 12 wk). For type I fibers, increases of 17% (P less than 0.05) in SDH activity occurred during 2nd wk, remained elevated through 4th wk, and increased further (P less than 0.05) to 137% of 1-wk values by the end of 6th wk. No further increases were noted between 6 and 12 wk. A similar maturational trend was evident for type IIa fibers, although SDH activities remained higher throughout development when compared with type I fibers. In contrast, SDH in type IIb fibers, although increasing by 14% during the first two measurement weeks (P less than 0.05), declined from 6 to 9 wk before ultimately reaching a value similar to 3 wk. SDH activity was also assessed in a typical slow- (soleus) and fast-twitch (extensor digitorum longus, EDL) muscle of the hindlimb to contrast their development with that of the diaphragm. Generally, SDH in type I and IIa fibers was approximately 40 and 20% higher, respectively, in the diaphragm than in matched fiber types in the other muscles throughout development (diaphragm greater than EDL greater than soleus).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of electrical stimulation patterns on glucose transport in rat muscles

1996 ◽  
Vol 271 (2) ◽  
pp. R426-R431 ◽  
Author(s):  
E. Johannsson ◽  
J. Jensen ◽  
K. Gundersen ◽  
H. A. Dahl ◽  
A. Bonen
Keyword(s):  
Extensor Digitorum Longus ◽  
Bolus Injection ◽  
Fold Increase ◽  
Transport Rate ◽  
Type I ◽  
Fiber Types ◽  
Glut 4 ◽  
Stimulation Period ◽  
Type I Fibers ◽  
White Gastrocnemius

Transport of 2-[3H]deoxy-D-glucose (2-DG) was investigated during supramaximal stimulations of different muscles. In addition, we varied the net stimulation time (NST). In different treatments, NST occupied either 5, 7.5, 10, 15, 20, 30, or 50% of a 20-min stimulation period. After a bolus injection of 3H-labeled 2-DG, the greatest transport occurred in the extensor digitorum longus. In red gastrocnemius (RG; type IIa fibers) and white gastrocnemius (WG; type IIb fibers), the 2-DG transport rate was highest at 10% NST (8- to 12-fold increase) and decreased thereafter. In soleus (type I fibers), the 2-DG transport increased from 5 to 50% NST. Below 30% NST, 2-DG transport was greater in RG and WG muscles than in soleus (P < 0.05). GLUT-4 and 2-DG transport were not correlated during the contractions. Therefore, the percent NST affects 2-DG transport differentially in muscles of varying fiber types, and the transport rate is not related to the GLUT-4 content of the muscles.

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