Characterization of Skeletal Muscle Regeneration Revealed a Novel Growth Network Induced by Molecular Acupuncture-like Transfection.

The low efficiency of in vivo transfection of a few fibres revealed a novel tissue network that temporally amplified growth stimulation in the entire regenerating rat soleus muscle. This acupuncture-like effect was demonstrated when the fibres began to grow after complete fibre degradation, synchronous inflammation, myoblast and myotube formation. Neonatal sarcoplasmic/endoplasmic reticulum ATPase (SERCA1b) was first detected in this system.

The Meeting of Micropeptides with Major Ca Pumps in Inner Membranes-Consideration of a New Player, SERCA1b.

Calcium is a major signalling bivalent cation within the cell. Compartmentalization is essential for regulation of calcium mediated processes. A number of players contribute to intracellular handling of calcium, among them are the sarco/endoplasmic reticulum calcium ATP-ases (SERCAs).

Poststerone increases muscle fibre size partly similar to its metabolically parent compound, 20-hydroxyecdysone.

In mice, poststerone is a major in vivo metabolite of the worldwide popular anabolic food supplement 20-hydroxyecdysone (20E). Here we present the first study on this ecdysteroid in view of the in vivo anabolic effect of its parent compound, 20E in mammals. We have monitored muscle fibre type cross sectional areas (CSA) of developing rats after treatment with poststerone as we did in a previous study with 20E.

Follistatin treatment suppresses SERCA1b levels independently of other players of calcium homeostasis in C2C12 myotubes.

Follistatin (FS) is a high affinity activin-binding protein, neutralizing the effects of the Transforming Growth Factor-beta (TGF-β) superfamily members, as myostatin (MSTN). Since MSTN emerged as a negative regulator, FS has been considered as a stimulator of skeletal muscle growth and differentiation. Here, we studied the effect of FS administration on the Ca-homeostasis of differentiating C2C12 skeletal muscle cells.

The Effect of SERCA1b Silencing on the Differentiation and Calcium Homeostasis of C2C12 Skeletal Muscle Cells.

The sarcoplasmic/endoplasmic reticulum Ca2+ATPases (SERCAs) are the main Ca2+ pumps which decrease the intracellular Ca2+ level by reaccumulating Ca2+ into the sarcoplasmic reticulum. The neonatal SERCA1b is the major Ca2+ pump in myotubes and young muscle fibers. To understand its role during skeletal muscle differentiation its synthesis has been interfered with specific shRNA sequence.

The neonatal sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA1b): a neglected pump in scope.

The neonatal isoform of the sarcoplasmic/endoplasmic reticulum Ca(2+) ATPase (SERCA1b) is formed by developmental splicing and expressed fully only in developing muscle. As a major Ca(2+) pump in myotubes, SERCA1b must be detected in excitation contraction coupling or in store-operated calcium entry. The available pan SERCA1 antibodies also recognise SERCA1b but these are more frequently used to detect SERCA1a, the adult muscle-specific isoform characteristically expressed in fast fibres of skeletal muscle.

The neonatal sarcoplasmic reticulum Ca2+-ATPase gives a clue to development and pathology in human muscles.

The sarcoplasmic/endoplasmic reticulum calcium ATPase 1 (SERCA1) has two muscle specific splice isoforms; SERCA1a in fast-type adult and SERCA1b in neonatal and regenerating skeletal muscles. At the protein level the only difference between these two isoforms is that SERCA1a has C-terminal glycine while SERCA1b has an octapeptide tail instead. This makes the generation of a SERCA1a specific antibody not feasible.

The compact mutation of myostatin causes a glycolytic shift in the phenotype of fast skeletal muscles.

Myostatin is an important negative regulator of skeletal muscle growth. The hypermuscular Compact (Cmpt) mice carry a 12-bp natural mutation in the myostatin propeptide, with additional modifier genes being responsible for the phenotype. Muscle cellularity of the fast-type tibialis anterior (TA) and extensor digitorum longus (EDL) as well as the mixed-type soleus (SOL) muscles of Cmpt and wild-type mice was examined by immunohistochemical staining of the myosin heavy chain (MHC) proteins.

SERCA1 protein expression in muscle of patients with Brody disease and Brody syndrome and in cultured human muscle fibers.

Brody disease is an inherited myopathy associated with a defective function of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase 1 (SERCA1) protein. Mutations in the ATP2A1 gene have been reported only in some patients. Therefore it has been proposed to distinguish patients with ATP2A1 mutations, Brody disease (BD), from patients without mutations, Brody syndrome (BS).

Transfection efficiency along the regenerating soleus muscle of the rat.

We investigated the efficiency of a single plasmid transfection along the longitudinal axis of the regenerating soleus of young rats. This also reflected transfection efficiency along the fibers because the soleus is a nearly fusiform muscle in young animals. The complete regeneration was induced by notexin and the transfection was made by intramuscular injection of enhanced green fluorescent protein- or Discosoma red-coding plasmids after 4 days.

Silencing SERCA1b in a few fibers stimulates growth in the entire regenerating soleus muscle.

The neonatal isoform of the sarcoplasmic/endoplasmic reticulum Ca²(+) ATPase 1 (SERCA1b) is a dominant Ca²(+) pump in the young fibers of regenerating muscle. In vivo transfection of about 1% of the fibers with SERCA1b RNAi plasmid resulted in no apparent change in the transfected fibers, but enhanced the increase of fresh weight and fiber size in the whole regenerating rat soleus muscle, until the normal size was reached. Co-transfection of calcineurin inhibitor cain/cabin-1 with SERCA1b RNAi was sufficient to cut down the widespread growth stimulation, but the subsequent transfection of cain into the SERCA1b RNAi transfected muscle did not inhibit muscle growth.

Phytoecdysteroids and vitamin D analogues--similarities in structure and mode of action.

Phytoecdysteroids are plant steroids with identical or analogue structures to the molting hormone in arthropods. The ecdysteroids exert several beneficial effects on mammals, from which the most cited and deeply examined one is the increase of muscle size and strength. This shows similarities with the mode of action of the androgenic steroids but the ecdysteroids do not bind to the cytoplasmic/nuclear receptor of the mammalian steroids.

The slow sarco/endoplasmic reticulum Ca2+ -ATPase declines independently of slow myosin in soleus muscle of diabetic rats.

The sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) isoforms are normally expressed in coordination with the corresponding myosin heavy chain (MyHC) isoforms in the fibers of skeletal muscle but this coordination is often disrupted in pathological conditions. In the streptozotocin-induced diabetes of rats (stz-rats), the soleus muscle showed peripheral neuropathy and the SERCA2a level decreased in type I (slow-oxidative) fibers compared to the control muscles, whereas the expression of the corresponding slow MyHC1 did not change. No difference was found at the mRNA and protein levels of SERCA and MyHC isoforms in the whole soleus, except that the level of the SERCA2a protein specifically declined in stz-rats compared to the controls.

dnRas stimulates autocrine-paracrine growth of regenerating muscle via calcineurin-NFAT-IL-4 pathway.

Ras and calcineurin are members of two independent pathways in muscle growth but their interaction is not known. This work shows that the transfection of about 1% of the muscle fibers with dominant negative Ras (dnRas) shows a wilder effect; it stimulates the fiber growth in the entire regenerating soleus muscle, including the nontransfected fibers. Co-transfection with the calcineurin inhibitor cain/cabin prevented the growth stimulation.

The effect of passive movement on denervated soleus highlights a differential nerve control on SERCA and MyHC isoforms.

The sarco-endoplasmic reticulum Ca2+ ATP-ase (SERCA) and myosin heavy chain (MyHC) levels were measured in hindlimb-denervated and selectively denervated rat soleus muscles. Selective denervation allowed passive movement of the soleus, whereas hindlimb denervation rendered it to passivity. To minimize chronic effects, we followed the changes only for 2 weeks.

20-Hydroxyecdysone increases fiber size in a muscle-specific fashion in rat.

20-Hydroxyecdysone (20E) is an ecdysteroid hormone that regulates moulting in insects. Interestingly, 20E is also found most abundantly in plant species and has anabolic effects in vertebrates, i.e.

Phytoecdysteroids and anabolic-androgenic steroids--structure and effects on humans.

Phytoecdysteroids are structural analogs of the insect molting hormone ecdysone. Plants comprise rich sources of ecdysteroids in high concentration and with broad structural diversity. Ecdysteroids have a number of proven beneficial effects on mammals but the hormonal effects of ecdysteroids have been proven only in arthropods.

The expression of the neonatal sarcoplasmic reticulum Ca2+ pump (SERCA1b) hints to a role in muscle growth and development.

The neonatal isoform of sarcoplasmic/endoplasmic reticulum Ca2+ ATPase 1 (SERCA1b) is a Ca2+ pump with a well-known developmentally regulated transcript level but an undefined protein expression and function. Specific antibodies were generated to show that SERCA1b is exclusively expressed in myoblasts and myotubes of cultured and regenerating muscle. However, the SERCA1b protein was not detectable in normal adult fast and slow muscles.

Intermittent spontaneous breathing protects the rat diaphragm from mechanical ventilation effects.

Objective: Short-term mechanical ventilation has been proven to reduce diaphragm force and fiber dimensions. We hypothesized that intermittent spontaneous breathing during the course of mechanical ventilation would minimize the effects of mechanical ventilation on diaphragm force and expression levels of transcription factors (MyoD and myogenin).

Design: Randomized, controlled experiment.

Sarcolipin and phospholamban mRNA and protein expression in cardiac and skeletal muscle of different species.

The widely held view that SLN (sarcolipin) would be the natural inhibitor of SERCA1 (sarcoplasmic/endoplasmic-reticulum Ca2+-ATPase 1), and PLB (phospholamban) its counterpart for SERCA2 inhibition is oversimplified and partially wrong. The expression of SLN and PLB mRNA and protein relative to SERCA1 or SERCA2 was assessed in ventricle, atrium, soleus and EDL (extensor digitorum longus) of mouse, rat, rabbit and pig. SLN protein levels were quantified by means of Western blotting using what appears to be the first successfully generated antibody directed against SLN.

Molecular forms of acetylcholinesterase in the rat extensor digitorum longus and soleus muscles regenerating from notexin-induced necrosis.

The activity of acetylcholinesterase molecular forms were examined after separation on sucrose gradients during notexin-induced necrosis and the following regeneration in rat extensor digitorum longus (EDL) and soleus (SOL) muscles. All forms dropped rapidly in both muscles in the first few days after single notexin injection. After a delay small globular forms (G1+G2) started to regenerate from day 7 and larger forms (G4 and A12) from day 10 in EDL.

Neocortical c-fos mRNA transcription in repeated, brief, acute seizures: is c-fos a coincidence detector?

The effect of acute brief seizures on neocortical c-fos expression was investigated in rats injected with 5 mg/kg 4-aminopyridine. Electroencephalography in freely moving animals with implanted neocortical electrodes detected an average of 2.67 tonic-clonic convulsions within 1 h following the 4-AP treatment.

Expression of SERCA2a is not regulated by calcineurin or upon mechanical unloading in skeletal muscle regeneration.

This study investigates to what extent the expression of the slow myosin heavy chain (MyHCI) isoform and the slow type sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) isoform are co-regulated in fibers of regenerating skeletal soleus muscle. Both overexpression of cain, a calcineurin inhibitor, or partial tenotomy prevented the expression of MyHCI but left SERCA2a expression unaffected in fibers of regenerating soleus muscles. These data complement those from different experimental models and clearly show that the expression of MyHCI and SERCA2a--the major proteins mediating, respectively, the slow type of contraction and relaxation--are not coregulated in regenerating soleus muscle.

The calcineurin activity and MCIP1.4 mRNA levels are increased by innervation in regenerating soleus muscle.

The level of active subunit of calcineurin and the calcineurin (Cn) enzyme activity are increased in innervated but not in denervated slow type regenerating skeletal soleus muscle. These nerve-dependent increases were not accompanied by similar increases in the mRNA levels. The changes in the mRNA level of the modulatory calcineurin interacting protein, MCIP1.