Microarray analysis of mdx mice expressing high levels of utrophin: therapeutic implications for dystrophin deficiency

Identification of immune-related features involved in Duchenne muscular dystrophy: A bidirectional transcriptome and proteome-driven analysis

Background

We aimed to investigate the biological mechanism and feature genes of Duchenne muscular dystrophy (DMD) by multi-omics and experimental verification strategy.

Methods

We integrated the transcriptomic and proteomic methods to find the differentially expressed mRNAs (DEMs) and proteins (DEPs) between DMD and Control groups. Weighted gene co-expression network analysis (WGCNA) was then used to identify modules of highly correlated genes and hub genes. In the following steps, the immune and stromal cells infiltrations were accomplished by xCELL algorithm. Furthermore, TF and miRNA prediction were performed with Networkanalyst. ELISA, western blot and external datasets were performed to verify the key proteins/mRNAs in DMD patient and mouse. Finally, a nomogram model was established based on the potential biomarkers.

Results

4515 DEMs and 56 DEPs were obtained from the transcriptomic and proteomic study respectively. 14 common genes were identified, which is enriched in muscle contraction and inflammation-related pathways. Meanwhile, we observed 33 significant differences in the infiltration of cells in DMD. Afterwards, a total of 22 miRNAs and 23 TF genes interacted with the common genes, including TFAP2C, MAX, MYC, NFKB1, RELA, hsa-miR-1255a, hsa-miR-130a, hsa-miR-130b, hsa-miR-152, and hsa-miR-17. In addition, three genes (ATP6AP2, CTSS, and VIM) showed excellent diagnostic performance on discriminating DMD in GSE1004, GSE3307, GSE6011 and GSE38417 datasets (all AUC > 0.8), which is validated in patients (10 DMD vs. 10 controls), DMD with exon 55 mutations, mdx mouse, and nomogram model.

Conclusion

Taken together, ATP6AP2, CTSS, and VIM play important roles in the inflammatory response in DMD, which may serve as diagnostic biomarkers and therapeutic targets.

Multiomic Approaches to Uncover the Complexities of Dystrophin-Associated Cardiomyopathy

Despite major progress in treating skeletal muscle disease associated with dystrophinopathies, cardiomyopathy is emerging as a major cause of death in people carrying dystrophin gene mutations that remain without a targeted cure even with new treatment directions and advances in modelling abilities. The reasons for the stunted progress in ameliorating dystrophin-associated cardiomyopathy (DAC) can be explained by the difficulties in detecting pathophysiological mechanisms which can also be efficiently targeted within the heart in the widest patient population. New perspectives are clearly required to effectively address the unanswered questions concerning the identification of authentic and effectual readouts of DAC occurrence and severity. A potential way forward to achieve further therapy breakthroughs lies in combining multiomic analysis with advanced preclinical precision models. This review presents the fundamental discoveries made using relevant models of DAC and how omics approaches have been incorporated to date.

CCR2 improves homing and engraftment of adipose-derived stem cells in dystrophic mice

Background

Dystrophinopathy, a common neuromuscular disorder caused by the absence of dystrophin, currently lacks effective treatments. Systemic transplantation of adipose-derived stem cells (ADSCs) is a promising treatment approach, but its low efficacy remains a challenge. Chemokine system-mediated stem cell homing plays a critical role in systemic transplantation. Here, we investigated whether overexpression of a specific chemokine receptor could improve muscle homing and therapeutic effects of ADSC systemic transplantation in dystrophic mice.

Methods

We analysed multiple microarray datasets from the Gene Expression Omnibus to identify a candidate chemokine receptor and then evaluated the protein expression of target ligands in different tissues and organs of dystrophic mice. The candidate chemokine receptor was overexpressed using the lentiviral system in mouse ADSCs, which were used for systemic transplantation into the dystrophic mice, followed by evaluation of motor function, stem cell muscle homing, dystrophin expression, and muscle pathology.

Results

Chemokine-profile analysis identified C–C chemokine receptor (CCR)2 as the potential target for improving ADSC homing. We found that the levels of its ligands C–C chemokine ligand (CCL)2 and CCL7 were higher in muscles than in other tissues and organs of dystrophic mice. Additionally, CCR2 overexpression improved ADSC migration ability and maintained their multilineage-differentiation potentials. Compared with control ADSCs, transplantation of those overexpressing CCR2 displayed better muscle homing and further improved motor function, dystrophin expression, and muscle pathology in dystrophic mice.

Conclusions

These results demonstrated that CCR2 improved ADSC muscle homing and therapeutic effects following systemic transplantation in dystrophic mice.

Short-Term ONX-0914 Administration: Performance and Muscle Phenotype in Mdx Mice

Duchenne muscular dystrophy (DMD) is a severe muscle-wasting disease. Although the lack of dystrophin protein is the primary defect responsible for the development of DMD, secondary disease complications such as persistent inflammation contribute greatly to the pathogenesis and the time-dependent progression of muscle destruction. The immunoproteasome is a potential therapeutic target for conditions or diseases mechanistically linked to inflammation. In this study, we explored the possible effects of ONX-0914 administration, an inhibitor specific for the immunoproteasome subunit LMP7 (ß5i), on motor performance, muscular pathology and protein degradation in 7-week old MDX mice, an age when the dystrophic muscles show extensive degeneration and regeneration. ONX-0914 (10 mg/kg) was injected subcutaneously on Day 2, 4, and 6. The mice were evaluated for physical performance (walking speed and strength) on Day 1 and 8. We show that this short-term treatment of ONX-0914 in MDX mice did not alter strength nor walking speed. The physical performance findings were consistent with no change in muscle inflammatory infiltration, percentage of central nuclei and proteasome content. Taken together, muscle structure and function in the young adult MDX mouse model are not altered with ONX-0914 treatment, indicating the administration of ONX-0914 during this critical time period does not exhibit any detrimental effects and may be an effective treatment of secondary complications of muscular dystrophy after further investigations.

Altered bone-regulating myokine expression in skeletal muscle Of Duchenne muscular dystrophy mouse models

INTRODUCTION

Duchenne muscular dystrophy (DMD) has been well characterized as a disease that affects both skeletal muscle and bone. The pathophysiology responsible for the deficits in bone tissue is still unclear.

METHODS

Quantitative reverse-transcription polymerase chain reaction and Western blot analyses of known myokines from skeletal muscle were performed on dystrophic mouse models and wild-type (WT) controls to identify differentially expressed bone-regulating myokines.

RESULTS

Twenty-four of 43 myokine genes demonstrated significantly different mRNA expression in the skeletal muscles of dystrophic mice when compared with muscles of WT mice. Several differently expressed bone-regulating myokine genes were identified, and their protein levels were also verified by Western blot.

CONCLUSIONS

Dystrophic skeletal muscle demonstrated a significantly altered myokine gene expression profile. mRNA and protein levels of several bone-regulating myokines were significantly altered in dystrophic skeletal muscle, which suggests pathological role of bone-regulating myokines on bone homeostasis in DMD. Muscle Nerve 58: 573-582, 2018.

Deregulation of Nrf2/ARE signaling pathway causes susceptibility of dystrophin-deficient myotubes to menadione-induced oxidative stress

Duchenne muscular dystrophy (DMD) is an X chromosome-linked disorder caused by a mutation in the dystrophin gene. Many previous studies reported that the skeletal muscles of DMD patients were more susceptible to oxidative stress than those of healthy people. However, not much has been known about the responsible mechanism of the differential susceptibility. In this study, we established dystrophin knock-down (DysKD) cell lines by transfection of dystrophin shRNA lentiviral particles into C2 cells and found that DysKD myotubes are more vulnerable to menadione-induced oxidative stress than control myotubes. We focused on the nuclear erythroid 2-related factor 2 (Nrf2) which is a transcription factor that regulates the expression of phase II antioxidant enzymes by binding to the antioxidant response element (ARE). Under menadione-induced oxidative stress, the translocation of Nrf2 to the nucleus is significantly decreased in the DysKD myotubes. In addition, the binding of Nrf2 to ARE site of Bcl-2 gene as well as protein expression of Bcl-2 is decreased compared to the control cells. Interestingly, sulforaphane increased Akt activation and Nrf2 translocation to the nucleus in the DysKD myotubes. These results suggest that the Nrf2 pathway might be the responsible pathway to the oxidative stress-induced muscle damage in DMD.

Identification of Sertoli cell-specific transcripts in the mouse testis and the role of FSH and androgen in the control of Sertoli cell activity

Background

The Sertoli cells act to induce testis differentiation and subsequent development in fetal and post-natal life which makes them key to an understanding of testis biology. As a major step towards characterisation of factors involved in Sertoli cell function we have identified Sertoli cell-specific transcripts in the mouse testis and have used the data to identify Sertoli cell-specific transcripts altered in mice lacking follicle-stimulating hormone receptors (FSHRKO) and/or androgen receptors (AR) in the Sertoli cells (SCARKO).

Results

Adult iDTR mice were injected with busulfan to ablate the germ cells and 50 days later they were treated with diphtheria toxin (DTX) to ablate the Sertoli cells. RNAseq carried out on testes from control, busulfan-treated and busulfan + DTX-treated mice identified 701 Sertoli-specific transcripts and 4302 germ cell-specific transcripts. This data was mapped against results from microarrays using testicular mRNA from 20 day-old FSHRKO, SCARKO and FSHRKO.SCARKO mice. Results show that of the 534 Sertoli cell-specific transcripts present on the gene chips, 85% were altered in the FSHRKO mice and 94% in the SCARKO mice (mostly reduced in both cases). In the FSHRKO.SCARKO mice additive or synergistic effects were seen for most transcripts. Age-dependent studies on a selected number of Sertoli cell-specific transcripts, showed that the marked effects in the FSHRKO at 20 days had largely disappeared by adulthood although synergistic effects of FSHR and AR knockout were seen.

Conclusions

These studies have identified the Sertoli cell-specific transcriptome in the mouse testis and have shown that most genes in the transcriptome are FSH- and androgen-dependent at puberty although the importance of FSH diminishes towards adulthood.

Electronic supplementary material

The online version of this article (10.1186/s12864-017-4357-3) contains supplementary material, which is available to authorized users.

Irisin treatment improves healing of dystrophic skeletal muscle

Background

Irisin is an exercise induced myokine that is shown to promote browning of adipose tissue and hence, increase energy expenditure. Furthermore, our unpublished results indicate that Irisin improves myogenic differentiation and induces skeletal muscle hypertrophy. Since exercise induced skeletal muscle hypertrophy improves muscle strength, we wanted to investigate if ectopic injection of Irisin peptide improves skeletal muscle function in a mouse model of muscular dystrophy. This utility of Irisin peptide is yet to be studied in animal models.

Methods

In order to test this hypothesis, we expressed and purified recombinant murine Irisin peptide from E. coli. Three- to six-week-old male mdx mice were injected IP with either vehicle (dialysis buffer) or Irisin recombinant peptide for two or four weeks, three times-a-week.

Results

Irisin injection increased muscle weights and enhanced grip strength in mdx mice. Improved muscle strength can be attributed to the significant hypertrophy observed in the Irisin injected mdx mice. Moreover, Irisin treatment resulted in reduced accumulation of fibrotic tissue and myofiber necrosis in mdx mice. In addition, Irisin improved sarcolemmal stability, which is severely compromised in mdx mice.

Conclusion

Irisin injection induced skeletal muscle hypertrophy, improved muscle strength and reduced necrosis and fibrotic tissue in a murine dystrophy model. These results demonstrate the potential therapeutic value of Irisin in muscular dystrophy.

Increased constitutive nitric oxide production by whole body periodic acceleration ameliorates alterations in cardiomyocytes associated with utrophin/dystrophin deficiency

Duchenne Muscular Dystrophy (DMD) cardiomyopathy is a progressive lethal disease caused by the lack of the dystrophin protein in the heart. The most widely used animal model of DMD is the dystrophin-deficient mdx mouse; however, these mice exhibit a mild dystrophic phenotype with heart failure only late in life. In contrast, mice deficient for both dystrophin and utrophin (mdx/utrn^-/-, or dKO) can be used to model severe DMD cardiomyopathy where pathophysiological indicators of heart failure are detectable by 8-10weeks of age. Nitric oxide (NO) is an important signaling molecule involved in vital functions of regulating rhythm, contractility, and microcirculation of the heart, and constitutive NO production affects the function of proteins involved in excitation-contraction coupling. In this study, we explored the efficacy of enhancing NO production as a therapeutic strategy for treating DMD cardiomyopathy using the dKO mouse model of DMD. Specifically, NO production was induced via whole body periodic acceleration (pGz), a novel non-pharmacologic intervention which enhances NO synthase (NOS) activity through sinusoidal motion of the body in a headward-footward direction, introducing pulsatile shear stress to the vascular endothelium and cardiomyocyte plasma membrane. Male dKO mice were randomized at 8weeks of age to receive daily pGz (480cpm, Gz±3.0m/s², 1h/d) for 4weeks or no treatment, and a separate age-matched group of WT animals (pGz-treated and untreated) served as non-diseased controls. At the conclusion of the protocol, cardiomyocytes from untreated dKO animals had, respectively, 4.3-fold and 3.5-fold higher diastolic resting concentration of Ca²⁺ ([Ca²⁺]_d) and Na⁺ ([Na⁺]_d) compared to WT, while pGz treatment significantly reduced these levels. For dKO cardiomyocytes, pGz treatment also improved the depressed contractile function, decreased oxidative stress, blunted the elevation in calpain activity, and mitigated the abnormal increase in [Ca²⁺]_d upon mechanical stress. These improvements culminated in a significant reduction in circulating cardiac troponin T (cTnT) and an extension of the median lifespan of dKO mice from 16 to 31weeks. Treatment with L-NAME (NOS inhibitor) significantly decreased overall lifespan and abolished the cardioprotective properties elicited by pGz. Our results provide evidence that enhancement of NO synthesis by pGz can ameliorate cellular dysfunction in dKO cardiomyocytes and may represent a novel therapeutic intervention in DMD cardiomyopathy patients.

Renin-angiotensin-aldosterone system inhibitors improve membrane stability and change gene-expression profiles in dystrophic skeletal muscles

Angiotensin-converting enzyme inhibitors (ACEi) and mineralocorticoid receptor (MR) antagonists are FDA-approved drugs that inhibit the renin-angiotensin-aldosterone system (RAAS) and are used to treat heart failure. Combined treatment with the ACEi lisinopril and the nonspecific MR antagonist spironolactone surprisingly improves skeletal muscle, in addition to heart function and pathology in a Duchenne muscular dystrophy (DMD) mouse model. We recently demonstrated that MR is present in all limb and respiratory muscles and functions as a steroid hormone receptor in differentiated normal human skeletal muscle fibers. The goals of the current study were to begin to define cellular and molecular mechanisms mediating the skeletal muscle efficacy of RAAS inhibitor treatment. We also compared molecular changes resulting from RAAS inhibition with those resulting from the current DMD standard-of-care glucocorticoid treatment. Direct assessment of muscle membrane integrity demonstrated improvement in dystrophic mice treated with lisinopril and spironolactone compared with untreated mice. Short-term treatments of dystrophic mice with specific and nonspecific MR antagonists combined with lisinopril led to overlapping gene-expression profiles with beneficial regulation of metabolic processes and decreased inflammatory gene expression. Glucocorticoids increased apoptotic, proteolytic, and chemokine gene expression that was not changed by RAAS inhibitors in dystrophic mice. Microarray data identified potential genes that may underlie RAAS inhibitor treatment efficacy and the side effects of glucocorticoids. Direct effects of RAAS inhibitors on membrane integrity also contribute to improved pathology of dystrophic muscles. Together, these data will inform clinical development of MR antagonists for treating skeletal muscles in DMD.

Differential Gene Expression Profiling of Dystrophic Dog Muscle after MuStem Cell Transplantation

BACKGROUND

Several adult stem cell populations exhibit myogenic regenerative potential, thus representing attractive candidates for therapeutic approaches of neuromuscular diseases such as Duchenne Muscular Dystrophy (DMD). We have recently shown that systemic delivery of MuStem cells, skeletal muscle-resident stem cells isolated in healthy dog, generates the remodelling of muscle tissue and gives rise to striking clinical benefits in Golden Retriever Muscular Dystrophy (GRMD) dog. This global effect, which is observed in the clinically relevant DMD animal model, leads us to question here the molecular pathways that are impacted by MuStem cell transplantation. To address this issue, we compare the global gene expression profile between healthy, GRMD and MuStem cell treated GRMD dog muscle, four months after allogenic MuStem cell transplantation.

RESULTS

In the dystrophic context of the GRMD dog, disease-related deregulation is observed in the case of 282 genes related to various processes such as inflammatory response, regeneration, calcium ion binding, extracellular matrix organization, metabolism and apoptosis regulation. Importantly, we reveal the impact of MuStem cell transplantation on several molecular and cellular pathways based on a selection of 31 genes displaying signals specifically modulated by the treatment. Concomitant with a diffuse dystrophin expression, a histological remodelling and a stabilization of GRMD dog clinical status, we show that cell delivery is associated with an up-regulation of genes reflecting a sustained enhancement of muscle regeneration. We also identify a decreased mRNA expression of a set of genes having metabolic functions associated with lipid homeostasis and energy. Interestingly, ubiquitin-mediated protein degradation is highly enhanced in GRMD dog muscle after systemic delivery of MuStem cells.

CONCLUSIONS

Overall, our results provide the first high-throughput characterization of GRMD dog muscle and throw new light on the complex molecular/cellular effects associated with muscle repair and the clinical efficacy of MuStem cell-based therapy.

Rapid depletion of muscle progenitor cells in dystrophic mdx/utrophin-/- mice

Duchenne muscular dystrophy (DMD) patients lack dystrophin from birth; however, muscle weakness becomes apparent only at 3-5 years of age, which happens to coincide with the depletion of the muscle progenitor cell (MPC) pools. Indeed, MPCs isolated from older DMD patients demonstrate impairments in myogenic potential. To determine whether the progression of muscular dystrophy is a consequence of the decline in functional MPCs, we investigated two animal models of DMD: (i) dystrophin-deficient mdx mice, the most commonly utilized model of DMD, which has a relatively mild dystrophic phenotype and (ii) dystrophin/utrophin double knock-out (dKO) mice, which display a similar histopathologic phenotype to DMD patients. In contrast to age-matched mdx mice, we observed that both the number and regeneration potential of dKO MPCs rapidly declines during disease progression. This occurred in MPCs at both early and late stages of myogenic commitment. In fact, early MPCs isolated from 6-week-old dKO mice have reductions in proliferation, resistance to oxidative stress and multilineage differentiation capacities compared with age-matched mdx MPCs. This effect may potentially be mediated by fibroblast growth factor overexpression and/or a reduction in telomerase activity. Our results demonstrate that the rapid disease progression in the dKO model is associated, at least in part, with MPC depletion. Therefore, alleviating MPC depletion could represent an approach to delay the onset of the histopathologies associated with DMD patients.

Gene and cell-mediated therapies for muscular dystrophy

Duchenne muscular dystrophy (DMD) is a devastating muscle disorder that affects 1 in 3,500 boys. Despite years of research and considerable progress in understanding the molecular mechanism of the disease and advancement of therapeutic approaches, there is no cure for DMD. The current treatment options are limited to physiotherapy and corticosteroids, and although they provide a substantial improvement in affected children, they only slow the course of the disorder. On a more optimistic note, more recent approaches either significantly alleviate or eliminate muscular dystrophy in murine and canine models of DMD and importantly, many of them are being tested in early phase human clinical trials. This review summarizes advancements that have been made in viral and nonviral gene therapy as well as stem cell therapy for DMD with a focus on the replacement and repair of the affected dystrophin gene.

Evaluation of potential synergistic action of a combined treatment with alpha-methyl-prednisolone and taurine on the mdx mouse model of Duchenne muscular dystrophy

AIMS

Glucocorticoids are the sole drugs clinically used in Duchenne muscular dystrophy, in spite of the relevant side effects. Combination of glucocorticoids with synergistic drugs may be one strategy to lower doses and control side effects, meanwhile providing wider control of the complex pathology. This study is a preclinical evaluation of the effect of a combined treatment of α-methyl-prednisolone (PDN) with taurine, a safe aminoacid with positive effects on some pathology-related events.

METHODS

PDN (1 mg/kg/day i.p.) and taurine (1 g/kg/day orally) were administered either alone or in combination, for 4-8 weeks to male dystrophic mdx mice chronically exercised on a treadmill. Effects were assessed in vivo and ex vivo with a variety of methodological approaches.

RESULTS

In vivo, each treatment significantly increased fore limb strength, a marked synergistic effect being observed with the combination PDN + taurine. Ex vivo, PDN + taurine completely restored the mechanical threshold, an electrophysiological index of calcium homeostasis, of extensor digitorum longus myofibres and the benefit was greater than for PDN alone. In parallel, the overactivity of voltage-independent cation channels in dystrophic myofibres was reduced. No effects were observed on plasma levels of creatine kinase, while lactate dehydrogenase was decreased by taurine and, to a minor extent, by PDN + taurine. A similar histology profile was observed in PDN and PDN + taurine-treated muscles. PDN + taurine significantly increased taurine level in fast-twitch muscle and brain, by high-pressure liquid chromatography analysis.

CONCLUSIONS

The combination PDN + taurine has additive actions on in vivo and ex vivo functional end points, with less evident advantages on histopathology and biochemical markers of the disease.

Neurofibromin (Nf1) is required for skeletal muscle development

Neurofibromatosis type 1 (NF1) is a multi-system disease caused by mutations in the NF1 gene encoding a Ras-GAP protein, neurofibromin, which negatively regulates Ras signaling. Besides neuroectodermal malformations and tumors, the skeletal system is often affected (e.g. scoliosis and long bone dysplasia) demonstrating the importance of neurofibromin for development and maintenance of the musculoskeletal system. Here, we focus on the role of neurofibromin in skeletal muscle development. Nf1 gene inactivation in the early limb bud mesenchyme using Prx1-cre (Nf1(Prx1)) resulted in muscle dystrophy characterized by fibrosis, reduced number of muscle fibers and reduced muscle force. This was caused by an early defect in myogenesis affecting the terminal differentiation of myoblasts between E12.5 and E14.5. In parallel, the muscle connective tissue cells exhibited increased proliferation at E14.5 and an increase in the amount of connective tissue as early as E16.5. These changes were accompanied by excessive mitogen-activated protein kinase pathway activation. Satellite cells isolated from Nf1(Prx1) mice showed normal self-renewal, but their differentiation was impaired as indicated by diminished myotube formation. Our results demonstrate a requirement of neurofibromin for muscle formation and maintenance. This previously unrecognized function of neurofibromin may contribute to the musculoskeletal problems in NF1 patients.

Role of thrombospondin 1 in macrophage inflammation in dysferlin myopathy

Muscle inflammation can be a prominent feature in several muscular dystrophies. In dysferlin myopathy, it is mainly composed of macrophages. To understand the origin of inflammation in dysferlin-deficient muscle, we analyzed soluble factors involved in monocyte chemotaxis released by myoblasts and myotubes from control and dysferlinopathy patients using a transwell system. Dysferlin-deficient myotubes released more soluble factors involved in monocyte chemotaxis compared with controls (p < 0.001). Messenger RNA microarray analysis showed a 3.2-fold increase of thrombospondin 1 (TSP-1) expression in dysferlin-deficient myotubes. Retrotranscriptasepolymerase chain reaction analysis, ELISA, and immunohistochemistry confirmed these results. Dysferlin mRNA knockdown with short-interfering RNA in normal myogenic cells resulted in TSP-1 mRNA upregulation and increased chemotaxis. Furthermore, monocyte chemotaxis was decreased when TSP-1 was blocked by specific antibodies. In muscle biopsies from dysferlinopathy patients, TSP-1 expression was increased in muscle fibers but not in biopsies of patientswith other myopathies with inflammation; TSP-1 was seen in some macrophages in all samples analyzed. Taken together, the data demonstrate that dysferlin-deficient muscle upregulates TSP-1 in vivoand in vitro and indicate that endogenous chemotactic factors arecrucial to the sustained inflammatory process observed in dysferlinopathies.

The artificial gene Jazz, a transcriptional regulator of utrophin, corrects the dystrophic pathology in mdx mice

The absence of the cytoskeletal protein dystrophin results in Duchenne muscular dystrophy (DMD). The utrophin protein is the best candidate for dystrophin replacement in DMD patients. To obtain therapeutic levels of utrophin expression in dystrophic muscle, we developed an alternative strategy based on the use of artificial zinc finger transcription factors (ZF ATFs). The ZF ATF 'Jazz' was recently engineered and tested in vivo by generating a transgenic mouse specifically expressing Jazz at the muscular level. To validate the ZF ATF technology for DMD treatment we generated a second mouse model by crossing Jazz-transgenic mice with dystrophin-deficient mdx mice. Here, we show that the artificial Jazz protein restores sarcolemmal integrity and prevents the development of the dystrophic disease in mdx mice. This exclusive animal model establishes the notion that utrophin-based therapy for DMD can be efficiently developed using ZF ATF technology and candidates Jazz as a novel therapeutic molecule for DMD therapy.

Early manifestation of alteration in cardiac function in dystrophin deficient mdx mouse using 3D CMR tagging

BACKGROUND

Duchenne muscular dystrophy (DMD) is caused by the absence of the cytoskeletal protein, dystrophin. In DMD patients, dilated cardiomyopathy leading to heart failure may occur during adolescence. However, early cardiac dysfunction is frequently undetected due to physical inactivity and generalized debilitation. The objective of this study is to determine the time course of cardiac functional alterations in mdx mouse, a mouse model of DMD, by evaluating regional ventricular function with CMR tagging.

METHODS

In vivo myocardial function was evaluated by 3D CMR tagging in mdx mice at early (2 months), middle (7 months) and late (10 months) stages of disease development. Global cardiac function, regional myocardial wall strains, and ventricular torsion were quantified. Myocardial lesions were assessed with Masson's trichrome staining.

RESULTS

Global contractile indexes were similar between mdx and C57BL/6 mice in each age group. Histology analysis showed that young mdx mice were free of myocardial lesions. Interstitial fibrosis was present in 7 month mdx mice, with further development into patches or transmural lesions at 10 months of age. As a result, 10 month mdx mice showed significantly reduced regional strain and torsion. However, young mdx mice showed an unexpected increase in regional strain and torsion, while 7 month mdx mice displayed similar regional ventricular function as the controls.

CONCLUSION

Despite normal global ventricular function, CMR tagging detected a biphasic change in myocardial wall strain and torsion, with an initial increase at young age followed by progressive decrease at older ages. These results suggest that CMR tagging can provide more sensitive measures of functional alterations than global functional indexes in dystrophin-related cardiomyopathies.

Muscle genome-wide expression profiling during disease evolution in mdx mice

Mdx mice show a milder phenotype than Duchenne patients despite bearing an analogous genetic defect. Our aim was to sort out genes, differentially expressed during the evolution of skeletal muscle mdx mouse disease, to elucidate the mechanisms by which these animals overcome the lack of dystrophin. Genome-wide microarray-based gene expression analysis was carried out at 3 wk and 1.5 and 3 mo of life. Candidate genes were selected by comparing: 1) mdx vs. controls at each point in time, and 2) mdx mice and 3) control mice among the three points in time. The first analysis showed a strong upregulation (96%) of inflammation-related genes and in >75% of genes related to cell adhesion, muscle structure/regeneration, and extracellular matrix remodeling during mdx disease evolution. Lgals3, Postn, Ctss, and Sln genes showed the strongest variations. The analysis performed among points in time demonstrated significant changes in Ecm1, Spon1, Thbs1, Csrp3, Myo10, Pde4b, and Adamts-5 exclusively during mdx mice lifespan. RT-PCR analysis of Postn, Sln, Ctss, Thbs1, Ecm1, and Adamts-5 expression from 3 wk to 9 mo, confirmed microarray data and demonstrated variations beyond 3 mo of age. A high-confidence functional network analysis demonstrated a strong relationship between them and showed two main subnetworks, having Dmd- Utrn- Myo10 and Adamts5- Thbs1- Spon1-Postn as principal nodes, which are functionally linked to Abca1, Actn4, Crebbp, Csrp3, Lama1, Lama3, Mical2, Mical3, Myf6, Pxn, and Sparc genes. Candidate genes may participate in the decline of muscle necrosis in mdx mice and could be considered potential therapeutic targets for Duchenne patients.

Effects of FSH on testicular mRNA transcript levels in the hypogonadal mouse

FSH acts through the Sertoli cell to ensure normal testicular development and function. To identify transcriptional mechanisms through which FSH acts in the testis, we have treated gonadotrophin-deficient hypogonadal (hpg) mice with recombinant FSH and measured changes in testicular transcript levels using microarrays and real-time PCR 12, 24 and 72 h after the start of treatment. Approximately 400 transcripts were significantly altered at each time point by FSH treatment. At 12 h, there was a clear increase in the levels of a number of known Sertoli cell transcripts (e.g. Fabp5, Lgals1, Tesc, Scara5, Aqp5). Additionally, levels of Leydig cell transcripts were also markedly increased (e.g. Ren1, Cyp17a1, Akr1b7, Star, Nr4a1). This was associated with a small but significant rise in testosterone at 24 and 72 h. At 24 h, androgen-dependent Sertoli cell transcripts were up-regulated (e.g. Rhox5, Drd4, Spinlw1, Tubb3 and Tsx) and this trend continued up to 72 h. By contrast with the somatic cells, only five germ cell transcripts (Dkkl1, Hdc, Pou5f1, Zfp541 and 1700021K02Rik) were altered by FSH within the time-course of the experiment. Analysis of canonical pathways showed that FSH induced a general decline in transcripts related to formation and regulation of tight junctions. Results show that FSH acts directly and indirectly to induce rapid changes in Sertoli cell and Leydig cell transcript levels in the hpg mouse but that effects on germ cell development must occur over a longer time-span.

Novel activation domain derived from Che-1 cofactor coupled with the artificial protein Jazz drives utrophin upregulation

Our aim is to upregulate the expression level of the dystrophin related gene utrophin in Duchenne muscular dystrophy, thus complementing the lack of dystrophin functions. To this end, we have engineered synthetic zinc finger based transcription factors. We have previously shown that the artificial three-zinc finger protein named Jazz fused with the Vp16 activation domain, is able to bind utrophin promoter A and to increase the endogenous level of utrophin in transgenic mice. Here, we report on an innovative artificial protein, named CJ7, that consists of Jazz DNA binding domain fused to a novel activation domain derived from the regulatory multivalent adaptor protein Che-1/AATF. This transcriptional activation domain is 100 amino acids in size and it is very powerful as compared to the Vp16 activation domain. We show that CJ7 protein efficiently promotes transcription and accumulation of the acetylated form of histone H3 on the genomic utrophin promoter locus.