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1.
Front Endocrinol (Lausanne) ; 14: 1236370, 2023.
Article in English | MEDLINE | ID: mdl-37795371

ABSTRACT

The prevalence of obesity has reached pandemic dimensions. It is associated with multiple comorbidities and is becoming a clinical and public health threat. Obesity is a multifactorial disease with a complex pathophysiology and interplay of various systems. A strong interplay exists between the neuro-endocrine system, the immune system with systemic chronic low-grade inflammation, and microbiome dysbiosis that can lead to the development of obesity, which in turn can exacerbate each of these factors, hence creating a vicious cycle. The conventional treatment with lifestyle modifications such as diet, physical exercise, pharmacotherapy, and bariatric surgery does not always result in sufficient weight control thus paving the way for other strategies. As one such strategy, acupuncture is increasingly used worldwide to treat obesity. This narrative review outlines the evidence for this neuro-endocrine-immune interplay in the pathophysiology of obesity. Furthermore, the existing experimental and clinical evidence of acupuncture as a multi-targeted therapy for obesity is explained and future research perspectives are discussed.


Subject(s)
Acupuncture Therapy , Bariatric Surgery , Humans , Obesity/therapy , Diet , Inflammation , Endocrine System
2.
Inflammopharmacology ; 30(3): 991-1003, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35347522

ABSTRACT

In the treatment of cancer, patients that receive anti-cancer drugs such as Vincristine develop peripheral neuropathic pain. Scyphocephalione A is a new bioactive compound isolated from Scyphocephalium ochocoa (Myristicaceae), a medicinal plant traditionally used in African countries. Recently, an in vitro study has shown its anti-inflammatory and cytotoxic activities on MCF-7 cell line of mammary carcinoma. The purpose of the present study was to assess the in vitro anti-inflammatory and in vivo anti-nociceptive activities of Scyphocephalione A. In vitro tests were carried out on cyclooxygenase and 5-lipoxygenase activities, and on protein denaturation; while in vivo tests were performed on acute and chronic pain models. It was noticed that Scyphocephalione A (1000 µg/ml), inhibits proteins denaturation, cyclooxygenase and 5-lipoxygenase activities respectively by 74.21%, 75.80% and 64.43%. The dose 50 mg/kg of Scyphocephalione A, inhibits acetic acid (63.43%, p < 0.001) and formalin (42.12%, p < 0.001) within first phase and 67.53% (p < 0.001) within second phase)-induced pains. At the same dose, Scyphocephalione A significantly inhibited mechanical and heat hyperalgesia, as well as cold allodynia induced by vincristine. In addition, the compound restored haematological, biochemical and oxidative stress parameters which were altered following Vincristine administration. These results suggest that Scyphocephalione A is endowed with anti-inflammatory potential and antinociceptive properties. Therefore, Scyphocephalione A can be classified as a promising molecule for the management of peripheral neuropathic pain triggered by anti-cancer drug.


Subject(s)
Antineoplastic Agents , Chronic Pain , Myristicaceae , Neuralgia , Analgesics/therapeutic use , Animals , Anti-Inflammatory Agents/therapeutic use , Antineoplastic Agents/therapeutic use , Arachidonate 5-Lipoxygenase , Chronic Pain/drug therapy , Cyclooxygenase 2/metabolism , Disease Models, Animal , Humans , Hyperalgesia/drug therapy , Myristicaceae/metabolism , Neuralgia/drug therapy , Plant Bark , Vincristine
3.
Can J Public Health ; 103(8 Suppl 2): S17-22, 2012 Apr 30.
Article in English | MEDLINE | ID: mdl-23618066

ABSTRACT

OBJECTIVES: To overcome the absence of socio-economic information in administrative databases and to monitor social inequalities in health, a material and social deprivation index was developed for Québec and Canada. METHODS: The index is based on the smallest area unit used in Canadian censuses, with 400 to 700 persons on average. It includes six socio-economic indicators grouped along two dimensions - material and social - produced from principal component analyses. The index exists for 1991, 1996, 2001 and 2006 and in different versions, from local areas to the whole of Canada. Numerous products related to the index are available online free of charge. RESULTS: The index has been used extensively in the field of health and social services, mainly in the province of Québec but also elsewhere in Canada. It has had four main uses, all related to public health: describing geographic variations of deprivation, illustrating inequalities in population health status and in service use according to deprivation, supporting the development of health reports and policies, and guiding regional resource allocation. These applications are facilitated by a close partnership between the producers and users of the index. CONCLUSION: The deprivation index is a marker of social inequalities in health. It allows for monitoring of inequalities over time and space, and constitutes a useful tool for public health planning, intervention and service delivery.


Subject(s)
Health Status Disparities , Small-Area Analysis , Canada , Humans , Quebec , Socioeconomic Factors
4.
Matrix Biol ; 29(4): 317-29, 2010 May.
Article in English | MEDLINE | ID: mdl-20193761

ABSTRACT

Glycosaminoglycans (GAG) are sulfated polysaccharides that play an important role in regulating cell functions. GAG mimetics called RGTAs (for ReGeneraTing Agents) have been shown to stimulate tissue repair. In particular they accelerate myogenesis, in part via their heparin-mimetic property towards growth factors. RGTAs also increase activity of calcium-dependent intracellular protease suggesting an effect on calcium cellular homeostasis. This effect was presently investigated on myoblasts in vitro using one member of the RGTA family molecule named OTR4120. We have shown that OTR4120 or heparin induced transient increases of intracellular calcium concentration ([Ca(2+)]i) in pre-fusing myoblasts from both mouse SolD7 cell line and rat skeletal muscle satellite cells grown in primary culture by mobilising sarcoplasmic reticulum store. This [Ca(2+)]i was not mediated by ryanodine receptors but instead resulted from stimulation of the Inositol-3 phosphate-phospholipase C activation pathway. OTR4120-induced calcium transient was not mediated through an ATP, nor a tyrosine kinase, nor an acetylcholine receptor but principally through serotonin 5-HT2A receptor. This original finding shows that the GAG mimetic can induce calcium signal through serotonin receptors and the IP3 pathway may be relevant to its ability to favour myoblast differentiation. It supports a novel and unexpected function of GAGs in the regulation of calcium homeostasis.


Subject(s)
Calcium/metabolism , Glycosaminoglycans/pharmacology , Myoblasts/metabolism , Animals , Calcium/pharmacology , Calcium, Dietary/metabolism , Calcium, Dietary/pharmacology , Cell Differentiation/drug effects , Cell Line , Clone Cells , Cytoplasm/metabolism , Glycosaminoglycans/metabolism , Heparin/metabolism , Heparin/pharmacology , Inositol Phosphates , Mice , Muscle Development/drug effects , Rats , Rats, Wistar , Receptor, Serotonin, 5-HT2A/metabolism , Regeneration/drug effects , Ryanodine Receptor Calcium Release Channel/metabolism , Ryanodine Receptor Calcium Release Channel/pharmacology , Satellite Cells, Skeletal Muscle/cytology , Satellite Cells, Skeletal Muscle/metabolism , Signal Transduction/drug effects
5.
J Nat Prod ; 70(12): 2006-9, 2007 Dec.
Article in English | MEDLINE | ID: mdl-18052322

ABSTRACT

A new dihydropyranone, ( R)-6-[( S)-2-hydroxy-4-(4-hydroxyphenyl)butyl]-5,6-dihydropyran-2-one ( 1), was isolated from Tapinanthus dodoneifolius. The structure was determined from spectroscopic and X-ray crystallographic analysis. Compound 1 (named dodoneine) showed a relaxing effect on preconstricted rat aortic rings (IC 50 of 81.4 +/- 0.9 microM).


Subject(s)
Aorta/drug effects , Loranthaceae/chemistry , Plants, Medicinal/chemistry , Pyrones/isolation & purification , Africa, Western , Animals , Crystallography, X-Ray , Molecular Conformation , Molecular Structure , Pyrones/chemistry , Pyrones/pharmacology , Rats , Stereoisomerism
6.
FASEB J ; 21(2): 608-17, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17202249

ABSTRACT

Calcium mishandling in Duchenne dystrophic muscle suggested that dystrophin, a membrane-associated cytoskeleton protein, might regulate calcium signaling cascade such as calcium influx pathway. It was previously shown that abnormal calcium entries involve uncontrolled stretch-activated currents and store-operated Ca2+ currents supported by TRPC1 channels. Moreover, our recent work demonstrated that reintroduction of minidystrophin in dystrophic myotubes restores normal capacitative calcium entries (CCEs). However, until now, no molecular link between the dystrophin complex and calcium entry channels has been described. This study is the first to show by coimmunoprecipitation assays the molecular association of TRPC1 with dystrophin and alpha1-syntrophin in muscle cells. TRPC1 was also associated with alpha1-syntrophin in dystrophic muscle cells independently of dystrophin. Furthermore, glutathione S-transferase (GST) pull-down assays showed that TRPC1 binds to the alpha1-syntrophin PDZ domain. Transfected recombinant alpha1-syntrophin formed a complex with TRPC1 channels and restored normal CCEs in dystrophic muscle cells. We suggest that normal regulation of CCEs in skeletal muscle depends on the association between TRPC1 channels and alpha1-syntrophin that may anchor the store-operated channels to the dystrophin-associated protein complex (DAPC). The loss of this molecular association could participate in the calcium alterations observed in dystrophic muscle cells. This study provides a new model for the regulation of calcium influx by interaction with the scaffold of the DAPC in muscle cells.


Subject(s)
Calcium-Binding Proteins/metabolism , Calcium/metabolism , Dystrophin/metabolism , Membrane Proteins/metabolism , Muscle Proteins/metabolism , TRPC Cation Channels/metabolism , Animals , Binding Sites , Calcium-Binding Proteins/genetics , Cell Line , Cytoskeleton/metabolism , Dystrophin-Associated Proteins/metabolism , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Immunoprecipitation , Membrane Proteins/genetics , Mice , Mice, Inbred C57BL , Microscopy, Confocal , Muscle Fibers, Skeletal/cytology , Muscle Fibers, Skeletal/metabolism , Muscle Proteins/genetics , Protein Binding , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism , Sarcolemma/metabolism , TRPC Cation Channels/genetics
7.
Toxicon ; 49(1): 117-22, 2007 Jan.
Article in English | MEDLINE | ID: mdl-17069869

ABSTRACT

A depolarizing activity following interaction with nicotinic acetylcholine receptors (nAchRs) in skeletal muscle cells, was observed for the first time in the non-toxic venom fraction (M1) of the yellow scorpion Buthus occitanus tunetanus (Bot). The effects of M1 fraction were tested on cultured rat myotubes by recording changes in [Ca2+]i. When applied, M1 (10 microg/mL) induced a transient increase of [Ca2+]i which could be blocked by a prior application of alpha-Bungarotoxin (alpha-Bg-Tx).


Subject(s)
Calcium Channels/drug effects , Muscle Fibers, Skeletal/drug effects , Muscle, Skeletal/cytology , Receptors, Nicotinic/drug effects , Scorpion Venoms/pharmacology , Scorpions , Animals , Calcium Channels/metabolism , Muscle Fibers, Skeletal/metabolism , Rats , Receptors, Nicotinic/metabolism
8.
Toxicon ; 48(4): 373-87, 2006 Sep 15.
Article in English | MEDLINE | ID: mdl-16904145

ABSTRACT

The effects of a non-toxic fraction, called M1, from Buthus occitanus tunetanus (Bot) scorpion were studied on rat cardiac contraction and calcium transient and current. A decrease in both rate and tension on isolated intact hearts as well as in calcium transient induced by depolarizing 100 K(+) solution on isolated ventricular cardiomyocytes was firstly observed. Studies with the whole cell patch clamp method showed that M1 decreased the L-type calcium current (ICa(L)) in a dose-dependent manner with an IC50 of 0.36 microg/mL and a Hill coefficient of 0.95. This effect was blocked and reversed by the specific muscarinic receptors antagonist atropine, 1 microM, and was completely prevented when cardiomyocytes were pretreated with Pertussis toxin, 1 microg/mL, to block the alpha subunit of the PTX-sensitive G proteins. These results show that M1 fraction of Bot inhibits basal calcium current by interacting with muscarinic receptors and suggest that this inhibition could be attributed to inhibition of adenylate cyclase activity by a mechanism involving PTX-sensitive G proteins.


Subject(s)
Adenylyl Cyclase Inhibitors , Calcium Channel Blockers/toxicity , Calcium Channels, L-Type/drug effects , Myocardial Contraction/drug effects , Receptor, Muscarinic M2/antagonists & inhibitors , Scorpion Venoms/toxicity , Animals , Calcium/metabolism , Cyclic AMP/biosynthesis , GTP-Binding Protein alpha Subunits, Gi-Go/antagonists & inhibitors , GTP-Binding Protein alpha Subunits, Gi-Go/physiology , Myocytes, Cardiac/drug effects , Myocytes, Cardiac/metabolism , Rats , Rats, Wistar
9.
J Gen Physiol ; 128(2): 219-30, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16847098

ABSTRACT

We present here evidence for the enhancement, at rest, of an inositol 1,4,5-trisphosphate (IP3)-mediated calcium signaling pathway in myotubes from dystrophin-deficient cell lines (SolC1(-)) as compared to a cell line from the same origin but transfected with mini-dystrophin (SolD(+)). With confocal microscopy, the number of sites discharging calcium (release site density [RSD]) was quantified and found more elevated in SolC1(-) than in SolD(+) myotubes. Variations of membrane potential had no significant effect on this difference, and higher resting [Ca2+]i in SolC1(-) (Marchand, E., B. Constantin, H. Balghi, M.C. Claudepierre, A. Cantereau, C. Magaud, A. Mouzou, G. Raymond, S. Braun, and C. Cognard. 2004. Exp. Cell Res. 297:363-379) cannot explain alone higher RSD. The exposure with SR Ca(2+) channel inhibitors (ryanodine and 2-APB) and phospholipase C inhibitor (U73122) significantly reduced RSD in both cell types but with a stronger effect in dystrophin-deficient SolC1(-) myotubes. Immunocytochemistry allowed us to localize ryanodine receptors (RyRs) as well as IP3 receptors (IP3Rs), IP3R-1 and IP3R-2 isoforms, indicating the presence of both RyRs-dependent and IP3-dependent release systems in both cells. We previously reported evidence for the enhancement, through a Gi protein, of the IP3-mediated calcium signaling pathway in SolC1(-) as compared to SolD(+) myotubes during a high K(+) stimulation (Balghi, H., S. Sebille, B. Constantin, S. Patri, V. Thoreau, L. Mondin, E. Mok, A. Kitzis, G. Raymond, and C. Cognard. 2006. J. Gen. Physiol. 127:171-182). Here we show that, at rest, these regulation mechanisms are also involved in the modulation of calcium release activities. The enhancement of resting release activity may participate in the calcium overload observed in dystrophin-deficient myotubes, and our findings support the hypothesis of the regulatory role of mini-dystrophin on intracellular signaling.


Subject(s)
Calcium Channels/physiology , Calcium Signaling/physiology , Dystrophin/physiology , Receptors, Cytoplasmic and Nuclear/physiology , Animals , Calcium/metabolism , Calcium Channel Blockers/pharmacology , Calcium Channels/analysis , Cell Line , Chelating Agents/pharmacology , Cytoplasm/metabolism , Down-Regulation , Dystrophin/deficiency , Dystrophin/genetics , Egtazic Acid/analogs & derivatives , Egtazic Acid/pharmacology , Estrenes/pharmacology , Inositol 1,4,5-Trisphosphate Receptors , Membrane Potentials/drug effects , Membrane Potentials/physiology , Mice , Mice, Inbred C3H , Mice, Knockout , Microscopy, Confocal , Muscle, Skeletal/cytology , Muscle, Skeletal/drug effects , Muscle, Skeletal/metabolism , Nuclear Envelope/metabolism , Phosphodiesterase Inhibitors/pharmacology , Potassium/pharmacology , Pyrrolidinones/pharmacology , Receptors, Cytoplasmic and Nuclear/analysis , Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors , Ryanodine/pharmacology , Ryanodine Receptor Calcium Release Channel/metabolism
10.
J Gen Physiol ; 127(2): 171-82, 2006 Feb.
Article in English | MEDLINE | ID: mdl-16446505

ABSTRACT

We present here evidence for the enhancement of an inositol 1,4,5-trisphosphate (IP3) mediated calcium signaling pathway in myotubes from dystrophin-deficient cell lines (SolC1(-)) as compared to a cell line from the same origin but transfected with mini-dystrophin (SolD(+)). With confocal microscopy, we demonstrated that calcium rise, induced by the perifusion of a solution containing a high potassium concentration, was higher in SolC1(-) than in SolD(+) myotubes. The analysis of amplitude and kinetics of the calcium increase in SolC1(-) and in SolD(+) myotubes during the exposure with SR Ca2+ channel inhibitors (ryanodine and 2-APB) suggested the presence of two mechanisms of SR calcium release: (1) a fast SR calcium release that depended on ryanodine receptors and (2) a slow SR calcium release mediated by IP3 receptors. Detection analyses of mRNAs (reverse transcriptase [RT]-PCR) and proteins (Western blot and immunolocalization) demonstrated the presence of the three known isoforms of IP3 receptors in both SolC1(-) and SolD(+) myotubes. Furthermore, analysis of the kinetics of the rise in calcium revealed that the slow IP3-dependent release may be increased in the SolC1(-) as compared to the SolD(+), suggesting an inhibitory effect of mini-dystrophin in this signaling pathway. Upon incubation with pertussis toxin (PTX), an inhibitory effect similar to that of the IP3R inhibitor (2-APB) was observed on K+-evoked calcium release. This result suggests the involvement of a Gi protein upstream of the IP3 pathway in these stimulation conditions. A hypothetical model is depicted in which both Gi protein and IP3 production could be involved in K+-evoked calcium release as well as a possible interaction with mini-dystrophin. Our findings demonstrate the existence of a potential relationship between mini-dystrophin and SR calcium release as well as a regulatory role of mini-dystrophin on intracellular signaling.


Subject(s)
Calcium Signaling , Calcium/metabolism , Dystrophin/physiology , GTP-Binding Proteins/physiology , Inositol 1,4,5-Trisphosphate/metabolism , Muscle Fibers, Skeletal/metabolism , Animals , Blotting, Western , Calcium Channels/analysis , Calcium Channels/chemistry , Calcium Channels/drug effects , Calcium Channels/genetics , Calcium Channels/metabolism , Calcium Channels/physiology , Cell Line , Down-Regulation , Dystrophin/analysis , Dystrophin/deficiency , Dystrophin/genetics , GTP-Binding Protein alpha Subunits, Gi-Go/physiology , Gene Expression , Inositol 1,4,5-Trisphosphate Receptors , Mice , Mice, Inbred C3H , Microscopy, Confocal , Pertussis Toxin/pharmacology , Potassium/pharmacology , RNA, Messenger/analysis , Receptors, Cytoplasmic and Nuclear/chemistry , Receptors, Cytoplasmic and Nuclear/genetics , Receptors, Cytoplasmic and Nuclear/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Ryanodine Receptor Calcium Release Channel/physiology
11.
Exp Cell Res ; 297(2): 363-79, 2004 Jul 15.
Article in English | MEDLINE | ID: mdl-15212940

ABSTRACT

Dystrophin is a cytoskeletal protein normally expressed underneath the sarcolemma of muscle fibers. The lack of dystrophin in Duchenne muscular Dystrophy (DMD) muscles results in fiber necrosis, which was proposed to be mediated by chronic calcium mishandling. The extensive comparison of dystrophic cells from human or mdx mice with normal muscles have suggested that the lack of dystrophin may alter the resting calcium permeability and steady-state levels of calcium, but this latter observation remains controversial. It is also not clear, whether calcium mishandling is resulting from the dystrophic process or if dystrophin can directly regulate calcium handling in muscle cells. This prompted us to determine if transfection of full-length dystrophin or Becker Muscular Dystrophy (BMD) minidystrophin, a candidate for viral-mediated gene therapy, could change calcium handling properties. We took advantage of specific properties of Sol8 cell line showing the absence of dystrophin expression together with a drastic calcium mishandling. Here, we show that full-length dystrophin allowed the recovery of a low resting intracellular-free calcium concentration together with lower calcium transients. We also show for the first time that stable expression of minidystrophin was able to restore normal calcium handling in Sol8 myotubes through a better control of steady-state levels, calcium transients, and subcellular calcium events. It suggests that dystrophin could play a regulatory role on calcium homeostasis apparatus and that functional links exist between calcium signaling and cytoskeleton.


Subject(s)
Calcium/metabolism , Dystrophin/metabolism , Muscle Fibers, Skeletal/metabolism , Muscle, Skeletal/metabolism , Animals , Carbocyanines , Cells, Cultured , Dystrophin/genetics , Fluorescent Dyes , Green Fluorescent Proteins , Homeostasis , Immunohistochemistry , Luminescent Proteins , Mice , Mice, Inbred C3H , Microinjections , Microscopy, Confocal , Muscle Fibers, Skeletal/cytology , Muscle Fibers, Skeletal/pathology , Muscle, Skeletal/cytology , Muscle, Skeletal/pathology , Muscular Dystrophy, Duchenne/pathology , Plasmids , Retroviridae/genetics
12.
Neoplasia ; 5(1): 83-92, 2003.
Article in English | MEDLINE | ID: mdl-12659673

ABSTRACT

SEMA3F, isolated from a 3p21.3 deletion, has antitumor activity in transfected cells, and protein expression correlates with tumor stage and histology. In primary tumors, SEMA3F and VEGF surface staining is inversely correlated. Coupled with SEMA3F at the leading edge of motile cells, we previously suggested that both proteins competitively regulate cell motility and adhesion. We have investigated this using the breast cancer cell line, MCF7. SEMA3F inhibited cell attachment and spreading as evidenced by loss of lamellipodia extensions, membrane ruffling, and cell-cell contacts, with cells eventually rounding-up and detaching. In contrast, VEGF had opposite effects. Although SEMA3F binds NRP2 with 10-fold greater affinity than NRP1, the effects in MCF7 were mediated by NRP1. This was determined by receptor expression and blocking of anti-NRP1 antibodies. Similar effects, but through NRP2, were observed in the C100 breast cancer cell line. Although we were unable to demonstrate changes in total GTP-bound Rac1 or RhoA, we did observe changes in the localization of Rac1-GFP using time lapse microscopy. Following SEMA3F, Rac1 moved to the base of lamellipodia and - with their collapse - to the membrane. These results support the concept that SEMA3F and VEGF have antagonistic actions affecting motility in primary tumor cell.


Subject(s)
Breast Neoplasms/pathology , Cell Adhesion/drug effects , Cell Movement/drug effects , Endothelial Growth Factors/pharmacology , Intercellular Signaling Peptides and Proteins/pharmacology , Lymphokines/pharmacology , Semaphorins/pharmacology , Animals , Breast Neoplasms/metabolism , COS Cells , Cell Membrane/metabolism , Cricetinae , DNA Primers/chemistry , Female , Gene Expression , Glutathione Transferase/metabolism , Humans , Immunoenzyme Techniques , Microscopy, Confocal , Neuropilin-1/genetics , Neuropilin-1/metabolism , Neuropilin-2/genetics , Neuropilin-2/metabolism , Polymerase Chain Reaction , Pseudopodia/metabolism , RNA, Messenger/metabolism , Signal Transduction , Tumor Cells, Cultured , Vascular Endothelial Growth Factor A , Vascular Endothelial Growth Factors , rac1 GTP-Binding Protein/metabolism , rhoA GTP-Binding Protein/metabolism
13.
Neuromuscul Disord ; 12(7-8): 665-73, 2002 Oct.
Article in English | MEDLINE | ID: mdl-12207936

ABSTRACT

This study aims to investigate the sodium/calcium exchanger expression in human co-cultured skeletal muscle cells and to compare the effects of Na(+)/Ca(2+) exchange activity in normal and dystrophic (Duchenne's muscular dystrophy) human co-cultured myotubes. For this purpose, variations of intracellular calcium concentration ([Ca(2+)](int)) were monitored, as the variations of the fluorescence ratio of indo-1 probe, in response to external sodium depletion. External sodium withdrawal induced [Ca(2+)](int) rises within several seconds in both normal and Duchenne's muscular dystrophy myotubes. These Na(+)-free-induced [Ca(2+)](int) elevations were attributed to the reverse mode of the Na(+)/Ca(2+) exchange mechanism since the phenomenon was dependent on extracellular calcium concentration ([Ca(2+)](ext)), and since it was sensitive to external Ni(2+) ions. Amplitudes of Na(+)-free-induced [Ca(2+)](int) rises were significantly greater in Duchenne's muscular dystrophy cells than in normal ones. Such a difference disappeared when the sarcoplasmic reticulum was pharmacologically blocked, suggesting that the reverse mode of the Na(+)/Ca(2+) exchange mechanism was able to generate enhanced calcium-induced calcium-release in Duchenne's muscular dystrophy myotubes. Immunostaining images of Na(+)/Ca(2+) exchanger (NCX) isoforms, obtained by confocal microscopy, revealed the presence of NCX1 and NCX3 at the sarcolemmal level of both normal and Duchenne's muscular dystrophy myotubes. No differences were observed in the location of NCX isoforms expression between normal and Duchenne's muscular dystrophy co-cultured myotubes.


Subject(s)
Calcium/metabolism , Dystrophin/metabolism , Muscle Fibers, Skeletal/metabolism , Muscular Dystrophy, Duchenne/metabolism , Sodium-Calcium Exchanger/metabolism , Sodium/metabolism , Adolescent , Adult , Biopsy , Calcium Signaling , Cell Culture Techniques , Humans , Immunohistochemistry , Microscopy, Confocal , Muscle Fibers, Skeletal/pathology , Muscle, Skeletal/metabolism , Muscular Dystrophy, Duchenne/pathology , Time Factors
14.
Neurosci Lett ; 323(3): 239-43, 2002 May 03.
Article in English | MEDLINE | ID: mdl-11959428

ABSTRACT

Duchenne muscular dystrophy (DMD) is characterized by the absence of dystrophin and an elevated intracellular calcium level. Single-channel recordings were performed with the cell-attached configuration of the patch-clamp technique. The present study shows, on human co-cultured normal and dystrophic muscle cells, the evidence for an increased activity of calcium permeant cationic mechano-sensitive channels under hypotonic medium stimulation. This activity was particularly enhanced in DMD cells. The hypotonic medium induced drastic changes in the single-channel activity characteristics, which are: a large increase of the calcium over potassium permeability ratio; and a great enhancement of the quantity of current crossing through these channels. These channels could contribute to a significant calcium entry, which could participate in the abnormal calcium homeostasis observed in DMD muscle.


Subject(s)
Calcium Channels/metabolism , Calcium/metabolism , Cell Membrane/metabolism , Muscle Fibers, Skeletal/metabolism , Muscle, Skeletal/metabolism , Muscular Dystrophy, Duchenne/metabolism , Adolescent , Adult , Calcium Channels/drug effects , Cation Transport Proteins/drug effects , Cation Transport Proteins/metabolism , Cations/pharmacology , Cell Membrane/drug effects , Cells, Cultured , Child , Child, Preschool , Gadolinium/pharmacology , Humans , Hypotonic Solutions/pharmacology , Membrane Potentials/drug effects , Membrane Potentials/physiology , Middle Aged , Muscle Fibers, Skeletal/drug effects , Muscle Fibers, Skeletal/pathology , Muscle, Skeletal/pathology , Muscle, Skeletal/physiopathology , Muscular Dystrophy, Duchenne/pathology , Muscular Dystrophy, Duchenne/physiopathology
15.
Neuromuscul Disord ; 12(3): 266-72, 2002 Mar.
Article in English | MEDLINE | ID: mdl-11801398

ABSTRACT

The aim of this study was to provide a set of data on mechanisms involved in the calcium homeostasis of facioscapulohumeral muscular dystrophy (FSHD) co-cultured myotubes. In fact, abnormal regulation of calcium have been shown in deficient dystrophin cells like Duchenne muscular dystrophy (DMD) cells, and it seemed interesting to study the calcium regulation in a pathologic cellular model which express dystrophin. T- and L-type calcium currents and contractile responses induced by membrane depolarisations as well as intracellular calcium transients induced by three kinds of stimulus (superfusions of acetylcholine, high K+ or caffeine containing media) were recorded by means of whole-cell patch-clamp and ratiometric cytofluorimetry in co-cultured FSHD myotubes which presented a sarcolemmal localisation of dystrophin. As judged from calcium currents properties, voltage-dependency of contractile responses or amplitude of evoked calcium transients, no clear difference in the calcium handling or calcium signalling was observed between this type of cell and the control cells, at least with the means and the conditions used in the present study. Since FSHD cells, contrary to DMD (Duchenne muscular dystrophy) cells, seemed to display both dystrophin expression and unaltered calcium regulation, the FSHD co-cultured cells appeared as a useful model of dystrophin-expressing pathological muscle cells to further investigate the link between dystrophin expression and intracellular calcium level regulation.


Subject(s)
Calcium/metabolism , Dystrophin/metabolism , Muscle Fibers, Skeletal/metabolism , Muscular Dystrophy, Facioscapulohumeral/metabolism , Calcium Channels, L-Type/metabolism , Calcium Channels, T-Type/metabolism , Calcium Signaling/physiology , Cells, Cultured , Coculture Techniques , Dystrophin/analysis , Electrophysiology , Homeostasis/physiology , Humans , Muscle Contraction/physiology , Muscle Fibers, Skeletal/chemistry , Muscle Fibers, Skeletal/cytology , Muscle, Skeletal/cytology
16.
J Biol Chem ; 277(15): 12978-87, 2002 Apr 12.
Article in English | MEDLINE | ID: mdl-11796721

ABSTRACT

We previously showed that alternatively spliced ankyrins-G, the Ank3 gene products, are expressed in skeletal muscle and localize to the postsynaptic folds and to the sarcoplasmic reticulum. Here we report the molecular cloning, tissue expression, and subcellular targeting of Ank(G107), a novel ankyrin-G from rat skeletal muscle. Ank(G107) lacks the entire ANK repeat domain and contains a 76-residue sequence near the COOH terminus. This sequence shares homology with COOH-terminal sequences of ankyrins-R and ankyrins-B, including the muscle-specific skAnk1. Despite widespread tissue expression of Ank3, the 76-residue sequence is predominantly detected in transcripts of skeletal muscle and heart, including both major 8- and 5.6-kb mRNAs of skeletal muscle. In 15-day-old rat skeletal muscle, antibodies against the 76-residue sequence localized to the sarcolemma and to the postsynaptic membrane and cross-reacted with three endogenous ankyrins-G, including one 130-kDa polypeptide that comigrated with in vitro translated Ank(G107). In adult muscle, these polypeptides appeared significantly decreased, and immunofluorescence labeling was no more detectable. Green fluorescent protein-tagged Ank(G107) transfected in primary cultures of rat myotubes was targeted to the plasma membrane. Deletion of the 76-residue insert resulted in additional cytoplasmic labeling suggestive of a reduced stability of Ank(G107) at the membrane. Recruitment of the COOH-terminal domain to the membrane was much less efficient but still possible only in the presence of the 76-residue insert. We conclude that the 76-residue sequence contributes to the localization and is essential to the stabilization of Ank(G107) at the membrane. These results suggest that tissue-dependent and developmentally regulated alternative processing of ankyrins generates isoforms with distinct sequences, potentially involved in specific protein-protein interactions during differentiation of the sarcolemma and, in particular, of the postsynaptic membrane.


Subject(s)
Ankyrins/metabolism , Amino Acid Sequence , Animals , Ankyrins/chemistry , Ankyrins/genetics , Base Sequence , Cells, Cultured , DNA, Complementary , Molecular Sequence Data , Muscle, Skeletal , Rats , Sequence Homology, Amino Acid , Subcellular Fractions/metabolism
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