MRF4, Myf-5, and myogenin mRNAs in the adaptive responses of mature rat muscle

1995 ◽  
Vol 268 (4) ◽  
pp. C1045-C1052 ◽  
Author(s):  
J. Jacobs-El ◽  
M. Y. Zhou ◽  
B. Russell
Keyword(s):  
Contractile Activity ◽  
Tibialis Anterior Muscle ◽  
Recovery Period ◽  
Low Frequency ◽  
Female Rats ◽  
Positive Staining ◽  
Mrna Levels ◽  
Adaptive Responses ◽  
Static Stretch

We studied the possible role of specific muscle regulatory factors (MRF) in the adaptive response to changes in contractile activity in mature skeletal muscle. The tibialis anterior muscle of anesthetized female rats was subjected to low-frequency stimulation, static stretch, or a combination of both. Message levels of MRF were observed after 2 h of activity, and the subsequent 20-h recovery period by slot blot and in situ hybridizations for MRF4, Myf-5, and myogenin. A combination of stimulation and stretch for 2 h increased MRF4 (11.6 +/- 5.3-fold) and Myf-5 (6.6 +/- 1.4-fold). In situ hybridization showed abundance in some regions of the muscle with positive staining near peripheral nuclei of both large and small fibers. Message levels remained high for 30 min and declined to near control levels by 20 h of recovery. Myogenin mRNA levels were unaffected by any manipulations. Neither stretch alone nor 10 Hz of electrical stimulation alone induced a significant increase in MRF. We conclude that myonuclei, and possibly activated myoblasts, increase expression of Myf-5 and MRF4 after a combination of both stimulation and stretch for 2 h.

Botulinum-induced muscle paralysis alters metabolic gene expression and fatigue recovery

1996 ◽  
Vol 270 (1) ◽  
pp. R238-R245 ◽  
Author(s):  
F. Gorin ◽  
K. Herrick ◽  
B. Froman ◽  
W. Palmer ◽  
R. Tait ◽  
...  
Keyword(s):  
Contractile Activity ◽  
Botulinum Toxin A ◽  
Tibialis Anterior Muscle ◽  
Low Frequency ◽  
Mrna Levels ◽  
Transcript Levels ◽  
Biochemical Alterations ◽  
Protein Levels ◽  
Metabolic Gene Expression ◽  
Fast Twitch

We evaluated the physiological, histochemical, and biochemical consequences of inhibiting contractile activity in rat skeletal muscles with botulinum toxin A (BTX). Contractile activity was entirely eliminated 12-18 h after a single, focal, intramuscular injection of BTX into the rat tibialis anterior muscle (TA). Neuromuscular transmission remained completely inhibited for 10-12 days, then slowly recovered. BTX-treated muscles exhibited a lower resistance to both high- and low-frequency fatigue at 7 and 14 days after injection, but contractile force recovered more rapidly in treated TA after fatigue. Treated TA showed a twofold increase in the activity of the triglyceride hydrolase enzyme lipoprotein lipase (LPL) and a comparable increase in the relative abundance of LPL steady-state mRNA. In contrast, there was a 28% reduction in protein levels of the muscle isozyme of glycogen phosphorylase (MGP) and a 70% decrease in relative MGP transcript levels. Similar changes in relative transcript levels of LPL and MGP were observed in the predominantly fast-twitch extensor digitorum longus after BTX injection, but relative LPL and MGP mRNA levels were not altered in predominantly slow-twitch soleus. Histochemical evidence indicated that fast-twitch glycolytic fibers had increased lipid content. These biochemical alterations were reversed 120 days after BTX treatment despite persistent atrophy.

Invited Review: Contractile activity-induced mitochondrial biogenesis in skeletal muscle

2001 ◽  
Vol 90 (3) ◽  
pp. 1137-1157 ◽  
Author(s):  
David A. Hood
Keyword(s):  
Transcription Factors ◽  
Respiratory Chain ◽  
Mitochondrial Biogenesis ◽  
Adenine Nucleotide ◽  
Contractile Activity ◽  
Recovery Period ◽  
Atp Synthesis ◽  
Nucleotide Metabolism ◽  
Significant Shift ◽  
Mrna Levels

Chronic contractile activity produces mitochondrial biogenesis in muscle. This adaptation results in a significant shift in adenine nucleotide metabolism, with attendant improvements in fatigue resistance. The vast majority of mitochondrial proteins are derived from the nuclear genome, necessitating the transcription of genes, the translation of mRNA into protein, the targeting of the protein to a mitochondrial compartment via the import machinery, and the assembly of multisubunit enzyme complexes in the respiratory chain or matrix. Putative signals involved in initiating this pathway of gene expression in response to contractile activity likely arise from combinations of accelerations in ATP turnover or imbalances between mitochondrial ATP synthesis and cellular ATP demand, and Ca2+ fluxes. These rapid events are followed by the activation of exercise-responsive kinases, which phosphorylate proteins such as transcription factors, which subsequently bind to upstream regulatory regions in DNA, to alter transcription rates. Contractile activity increases the mRNA levels of nuclear-encoded proteins such as cytochrome c and mitochondrial transcription factor A (Tfam) and mRNA levels of upstream transcription factors like c- junand nuclear respiratory factor-1 (NRF-1). mRNA level changes are often most evident during the postexercise recovery period, and they can occur as a result of contractile activity-induced increases in transcription or mRNA stability. Tfam is imported into mitochondria and controls the expression of mitochondrial DNA (mtDNA). mtDNA contributes only 13 protein products to the respiratory chain, but they are vital for electron transport and ATP synthesis. Contractile activity increases Tfam expression and accelerates its import into mitochondria, resulting in increased mtDNA transcription and replication. The result of this coordinated expression of the nuclear and the mitochondrial genomes, along with poorly understood changes in phospholipid synthesis, is an expansion of the muscle mitochondrial reticulum. Further understanding of 1) regulation of mtDNA expression, 2) upstream activators of NRF-1 and other transcription factors, 3) the identity of mRNA stabilizing proteins, and 4) potential of contractile activity-induced changes in apoptotic signals are warranted.

The worsening of tibialis anterior muscle atrophy during recovery post-immobilization correlates with enhanced connective tissue area, proteolysis, and apoptosis

2012 ◽  
Vol 303 (11) ◽  
pp. E1335-E1347 ◽  
Author(s):  
Lamia Slimani ◽  
Didier Micol ◽  
Julien Amat ◽  
Geoffrey Delcros ◽  
Bruno Meunier ◽  
...  
Keyword(s):  
Connective Tissue ◽  
Muscle Atrophy ◽  
Tibialis Anterior ◽  
Fiber Type ◽  
Tibialis Anterior Muscle ◽  
Recovery Period ◽  
Mrna Levels ◽  
Adult Rats ◽  
Extracellular Compartment ◽  
Nuclear Apoptosis

Sustained muscle wasting due to immobilization leads to weakening and severe metabolic consequences. The mechanisms responsible for muscle recovery after immobilization are poorly defined. Muscle atrophy induced by immobilization worsened in the lengthened tibialis anterior (TA) muscle but not in the shortened gastrocnemius muscle. Here, we investigated some mechanisms responsible for this differential response. Adult rats were subjected to unilateral hindlimb casting for 8 days (I8). Casts were removed at I8, and animals were allowed to recover for 10 days (R1 to R10). The worsening of TA atrophy following immobilization occurred immediately after cast removal at R1 and was sustained until R10. This atrophy correlated with a decrease in type IIb myosin heavy chain (MyHC) isoform and an increase in type IIx, IIa, and I isoforms, with muscle connective tissue thickening, and with increased collagen (Col) I mRNA levels. Increased Col XII, Col IV, and Col XVIII mRNA levels during TA immobilization normalized at R6. Sustained enhanced peptidase activities of the proteasome and apoptosome activity contributed to the catabolic response during the studied recovery period. Finally, increased nuclear apoptosis prevailed only in the connective tissue compartment of the TA. Altogether, the worsening of the TA atrophy pending immediate reloading reflects a major remodeling of its fiber type properties and alterations in the structure/composition of the extracellular compartment that may influence its elasticity/stiffness. The data suggest that sustained enhanced ubiquitin-proteasome-dependent proteolysis and apoptosis are important for these adaptations and provide some rationale for explaining the atrophy of reloaded muscles pending immobilization in a lengthened position.

Surfactant protein A expression is delayed in fetuses of streptozotocin-treated rats

1992 ◽  
Vol 262 (4) ◽  
pp. L489-L494 ◽  
Author(s):  
S. H. Guttentag ◽  
D. S. Phelps ◽  
W. Stenzel ◽  
J. B. Warshaw ◽  
J. Floros
Keyword(s):  
Protein A ◽  
Fetal Lung ◽  
Surfactant Protein ◽  
Female Rats ◽  
Surfactant Protein A ◽  
Mrna Levels ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Normal Expression

The content and distribution of the 26-to 38-kDa surfactant protein (SP-A) and its mRNA were determined in fetuses of control and streptozotocin (STZ)-treated Sprague-Dawley rats using immunohistochemistry, RNA blotting, and in situ hybridization. Female rats were treated with 50 mg/kg STZ before mating, and the fetuses were killed at fetal days 18-21 or on neonatal days 1 and 2 (day of birth = end of day 22). SP-A was barely detectable on fetal day 18 in controls and easily detected by fetal day 21. In the STZ group, SP-A was decreased compared with controls at fetal days 18-21. However, by neonatal days 1–2, there were no significant differences in SP-A levels between groups. SP-A mRNA was detectable at fetal day 18 in controls, but it was decreased in the STZ group at day 18-21 (P less than 0.02) and differences were no longer detected by neonatal days 1–2. SP-A and SP-A mRNA accumulated with advancing gestational age in both groups until neonatal days 1–2. The differences in SP-A and SP-A mRNA levels in the two groups diminished with advancing age but remained significant at fetal day 21. These data suggest that STZ-induced diabetes interferes with normal expression of SP-A in the developing fetal lung.

Effects of triiodothyronine, dexamethasone and estradiol-17β on GH mRNA in rat pituitary cells in culture as revealed by in situ hybridization

1991 ◽  
Vol 124 (1) ◽  
pp. 83-90 ◽  
Author(s):  
M. G. Martinoli ◽  
R. Veilleux ◽  
G. Pelletier
Keyword(s):  
In Situ Hybridization ◽  
Calf Serum ◽  
Female Rats ◽  
Pituitary Cells ◽  
Mrna Levels ◽  
Male And Female ◽  
Male And Female Rats ◽  
Rat Pituitary ◽  
Estradiol 17Β

Abstract. The GH lines of rat pituitary tumour cells have been largely used to study the regulation of GH mRNA. In order to investigate the role of T3, dexamethasone and estradiol-17β on GH expression in non-tumoural pituitary cells, we have used in situ hybridization techniques performed on rat anterior pituitary cells in monolayer culture. The amounts of mRNA encoding for GH, as evaluated by counting the number of grains per somatotrope, were markedly reduced after 4 days of culture in a steroid-free medium supplemented with an hypothyroid calf serum. Addition of T3 or dexamethasone for 3 days increased GH mRNA levels. The concomitant administration of the two hormones produced a synergistic effect on GH mRNA levels which became higher than those observed after T3 or dexamethasone administration alone. However, this effect did not restore GH mRNA levels to those measured in monolayer pituitary cells grown in medium containing 10% fetal calf serum. Moreover GH mRNA levels appeared higher in male than in female pituitary cells. The administration of E2 to pituitary cell cultures from both male and female rats produced an increase by 15, and 12.8% in GH mRNA levels in male and female, respectively. This stimulatory effect of E2 in cell culture was competitively blocked by simultaneous incubation with the antiestrogen LY156758 (Keoxifene). These results demonstrate that T3, dexamethasone as well as E2 act directly on somatotropic cells to regulate GH gene expression.

Sequential increases in capillarization and mitochondrial enzymes in low-frequency-stimulated rabbit muscle

1998 ◽  
Vol 274 (3) ◽  
pp. C810-C818 ◽  
Author(s):  
Dejan Škorjanc ◽  
Frank Jaschinski ◽  
Georg Heine ◽  
Dirk Pette
Keyword(s):  
Citrate Synthase ◽  
Contractile Activity ◽  
Fiber Type ◽  
Low Frequency ◽  
Mitochondrial Enzymes ◽  
Rabbit Muscle ◽  
Mrna Levels ◽  
Metabolic Potential ◽  
Oxidative Potential ◽  
Time Pattern

To investigate temporal changes in capillarization and increases in mitochondrial enzyme activity, rabbit tibialis anterior muscles underwent chronic low-frequency stimulation for up to 50 days. Capillary density (CD), capillary-to-fiber ratio (C/F), intercapillary distance (ICD), and mean capillary area (MCA), as well as several other parameters of capillarization, were examined. In addition, tissue levels of mRNA specific to vascular endothelial growth factor (VEGF) were assessed by reverse transcriptase-polymerase chain reaction. Citrate synthase (CS) activity, a marker of aerobic-oxidative metabolic potential, was measured in the same muscles. Significant increases in CD and C/F, respectively, and decreases in ICD and MCA were observed after 2 days. These changes reached stable maxima by 14 days. The increases in capillarization occurred in a fiber-type-specific manner, affecting type IId fibers before types IIda and IIa. VEGF mRNA levels increased in a bimodal time pattern with a first elevation (2.5-fold) after 1 day and a second (9-fold) after 6–8 days. Increases in CS were first noted after 8 days. Obviously, increases in capillarization as induced by enhanced contractile activity precede increases in the aerobic-oxidative potential of energy metabolism.

Regulation of Egr-1, SRF, and Sp1 mRNA expression in contracting skeletal muscle cells

2004 ◽  
Vol 97 (6) ◽  
pp. 2207-2213 ◽  
Author(s):  
Isabella Irrcher ◽  
David A. Hood
Keyword(s):  
Skeletal Muscle ◽  
Transcription Factors ◽  
Mrna Expression ◽  
Mitochondrial Biogenesis ◽  
Contractile Activity ◽  
Recovery Period ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Mrna Levels ◽  
Serum Response

The early cellular signals associated with contractile activity initiate the activation and induction of transcription factors that regulate changes in skeletal muscle phenotype. The transcription factors Egr-1, Sp1, and serum response factor (SRF) are potentially important mediators of mitochondrial biogenesis based on the prevalence of binding sites for them in the promoter regions of genes encoding mitochondrial proteins, including PGC-1α, the important regulator of mitochondrial biogenesis. Thus, to further define a role for transcription factors at the onset of contractile activity, we examined the time-dependent alterations in Egr-1, Sp1, and SRF mRNA and the levels in electrically stimulated mouse C2C12 skeletal muscle cells. Early transient increases in Egr-1 mRNA levels within 30 min ( P < 0.05) of contractile activity led to threefold increases ( P < 0.05) in Egr-1 protein by 60 min. The increase in Egr-1 mRNA was not because of increased stability, as Egr-1 mRNA half-life after 30 min of stimulation showed only a 58% decline. Stimulation of muscle cells had no effect on Sp1 mRNA but led to progressive increases ( P < 0.05) in SRF mRNA by 30 and 60 min. This was not matched by increases in SRF protein but occurred coincident with increases ( P < 0.05) in SRF-serum response element DNA binding at 30 and 60 min as a result of SRF phosphorylation on serine-103. To assess the importance of the recovery period, 12 h of continuous contractile activity was compared with four successive 3-h bouts, with an intervening 21-h recovery period after each bout. Continuous contractile activity led to a twofold increase ( P < 0.05) in Egr-1 mRNA, no change in SRF mRNA, and a 43% decrease in Sp1 mRNA expression. The recovery period prevented the decline in Sp1 mRNA, produced a decrease in Egr-1 mRNA, and had no effect on SRF mRNA. Thus continuous and intermittent contractile activity evoked different specific transcription factor expression patterns, which may ultimately contribute to divergent qualitative, or temporal patterns of, phenotypic adaptation in muscle.

Studies of oxytocin and vasopressin gene expression in the rat hypothalamus using exon- and intron-specific probes

2006 ◽  
Vol 290 (5) ◽  
pp. R1233-R1241 ◽  
Author(s):  
Chunmei Yue ◽  
Noriko Mutsuga ◽  
Elka M. Scordalakes ◽  
Harold Gainer
Keyword(s):  
Gene Expression ◽  
Mrna Degradation ◽  
Female Rats ◽  
Mrna Levels ◽  
Salt Loading ◽  
Rat Hypothalamus ◽  
Intron 2 ◽  
Vasopressin Gene ◽  
Insight Into

To develop a comprehensive approach for the study of oxytocin (OT) and vasopressin (VP) gene expression in the rat hypothalamus, we first developed an intronic riboprobe to measure OT heteronuclear RNA (hnRNA) levels by in situ hybridization histochemistry (ISHH). Using this 84-bp riboprobe, directed against intron 2 of the OT gene, we demonstrate strong and specific signals in neurons confined to the supraoptic (SON) and paraventricular (PVN) nuclei of the rat hypothalamus. We used this new intronic OT probe, together with other well-established intronic and exonic OT and VP probes, to reevaluate OT and VP gene expression in the hypothalamus under two classical physiological conditions, acute osmotic stimulation, and lactation. We found that magnocellular neurons in 7- to 8-day lactating female rats exhibit increased OT but not VP hnRNA. Since VP mRNA is increased during lactation, this suggests that decreased VP mRNA degradation during lactation may be responsible for this change. In contrast, whereas there was the expected large increase in VP hnRNA after acute salt loading, there was no change in OT hnRNA, suggesting that acute hyperosmotic stimuli produce increased VP but not OT gene transcription. Hence, the use of both exon- and intron-specific probes, which distinguish the changes in hnRNA and mRNA levels, respectively, can provide insight into the relative roles of transcription and mRNA degradation processes in changes in gene expression evoked by physiological stimuli.

scholarly journals Transient regulation of c-fos, αB-crystallin, and hsp70 in muscle during recovery from contractile activity

1998 ◽  
Vol 274 (2) ◽  
pp. C341-C346 ◽  
Author(s):  
P. Darrell Neufer ◽  
George A. Ordway ◽  
R. Sanders Williams
Keyword(s):  
Citrate Synthase ◽  
Contractile Activity ◽  
Motor Nerve ◽  
Tibialis Anterior Muscle ◽  
Stress Protein ◽  
Low Frequency ◽  
Oxidative Capacity ◽  
Hsp70 Mrna ◽  
Genes Encoding ◽  
Αb Crystallin

Endurance exercise training increases the oxidative capacity of skeletal muscles, reflecting the induction of genes encoding enzymes of intermediary metabolism. To test the hypothesis that changes in gene expression may be triggered specifically during recovery from contractile activity, we quantified c-fos, αB-crystallin, 70-kDa heat shock protein (hsp70), myoglobin, and citrate synthase RNA in rabbit tibialis anterior muscle during recovery from intermittent (8 h/day), low-frequency (10 Hz) motor nerve stimulation. Recovery from a single 8-h bout of stimulation was characterized by large (>10-fold) transient increases in c-fos, αB-crystallin, and hsp70 mRNA. Similar changes were noted during recovery after 7 or 14 days of stimulation (8 h/day). Myoglobin and citrate synthase mRNA were also induced during recovery, but the changes were of lesser magnitude (2- to 2.5-fold) and were observed only following repeated bouts of muscle activity (7th or 14th day) that promoted sustained (>24 h) increases in these transcripts. These findings indicate that recovery from exercise is associated with specific transient changes in the expression of immediate early and stress protein genes, suggesting that the products of these genes may have specific roles in the remodeling process evoked by repeated bouts of contractile activity.

scholarly journals Induced expression of syndecan in healing wounds.

1991 ◽  
Vol 114 (3) ◽  
pp. 585-595 ◽  
Author(s):  
K Elenius ◽  
S Vainio ◽  
M Laato ◽  
M Salmivirta ◽  
I Thesleff ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Hair Follicle ◽  
Granulation Tissue ◽  
Mouse Skin ◽  
Follicle Cells ◽  
Epithelial Cell Line ◽  
Positive Staining ◽  
Mrna Levels ◽  
Mrna Induction

We have studied the expression of an integral cell surface proteoglycan, syndecan, during the healing of cutaneous wounds, using immunohistochemical and in situ hybridization methods. In normal mouse skin, both syndecan antigen and mRNA were found to be expressed exclusively by epidermal and hair follicle cells. After incision and subsequent suturing, remarkably increased amounts of syndecan on the cell surfaces of migrating and proliferating epidermal cells and on hair follicle cells adjacent to wound margins were noted. This increased syndecan expression was shown to be a consequence of greater amounts of syndecan mRNA. Induction was observed already 1 d after wounding, was most significant at the time of intense cell proliferation, and was still observable 14 d after incision. The migrating cells of the leading edge of the epithelium also showed enhanced syndecan expression, although clearly less than that seen in the proliferating epithelium. The merging epithelial cells at the site of incision showed little or no syndecan expression; increased syndecan expression, however, was detected during later epithelial stratification. When wounds were left unsutured, in situ hybridization experiments also revealed scattered syndecan-positive signals in the granulation tissue near the migrating epidermal sheet. By immunohistochemical analysis, positive staining in granulation tissue was observed around vascular endothelial cells in a subpopulation of growing capillaries. Induction of syndecan in granulation tissue both at the protein and mRNA levels was temporally and spatially highly restricted. Granulation tissue, which formed in viscose cellulose sponge cylinders placed under the skin of rats, was also found to produce 3.4 and 2.6 kb mRNA species of syndecan similar to that observed in the normal murine mammary epithelial cell line, NMuMG. These results suggest that syndecan may have a unique and important role as a cell adhesion and a growth factor-binding molecule not only during embryogenesis but also during tissue regeneration in mature tissues.

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