scholarly journals Pathological evaluation of rats carrying in-frame mutations in the dystrophin gene: a new model of Becker muscular dystrophy

2020 ◽  
Vol 13 (9) ◽  
pp. dmm044701
Author(s):  
Naomi Teramoto ◽  
Hidetoshi Sugihara ◽  
Keitaro Yamanouchi ◽  
Katsuyuki Nakamura ◽  
Koichi Kimura ◽  
...  
Keyword(s):  
Muscular Dystrophy ◽  
Gene Mutations ◽  
Dystrophin Gene ◽  
Becker Muscular Dystrophy ◽  
Severe Form ◽  
Independent Manner ◽  
Glycoprotein Complex ◽  
Dystrophin Expression ◽  
Pathological Evaluation ◽  
Dystrophin Glycoprotein Complex

ABSTRACTDystrophin, encoded by the DMD gene on the X chromosome, stabilizes the sarcolemma by linking the actin cytoskeleton with the dystrophin-glycoprotein complex (DGC). In-frame mutations in DMD cause a milder form of X-linked muscular dystrophy, called Becker muscular dystrophy (BMD), characterized by the reduced expression of truncated dystrophin. So far, no animal model with in-frame mutations in Dmd has been established. As a result, the effect of in-frame mutations on the dystrophin expression profile and disease progression of BMD remains unclear. In this study, we established a novel rat model carrying in-frame Dmd gene mutations (IF rats) and evaluated the pathology. We found that IF rats exhibited reduced expression of truncated dystrophin in a proteasome-independent manner. This abnormal dystrophin expression caused dystrophic changes in muscle tissues but did not lead to functional deficiency. We also found that the expression of additional dystrophin named dpX, which forms the DGC in the sarcolemma, was associated with the appearance of truncated dystrophin. In conclusion, the outcomes of this study contribute to the further understanding of BMD pathology and help elucidate the efficiency of dystrophin recovery treatments in Duchenne muscular dystrophy, a more severe form of X-linked muscular dystrophy.

scholarly journals Cardiac Involvement in Dystrophin-Deficient Females: Current Understanding and Implications for the Treatment of Dystrophinopathies

Genes ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 765 ◽  
Author(s):  
Kenji Rowel Q. Lim ◽  
Narin Sheri ◽  
Quynh Nguyen ◽  
Toshifumi Yokota
Keyword(s):  
Muscular Dystrophy ◽  
Molecular Mechanisms ◽  
Cardiac Involvement ◽  
Gene Mutations ◽  
Dystrophin Gene ◽  
Becker Muscular Dystrophy ◽  
Female Carrier ◽  
Daily Life Activities ◽  
Cardiac Manifestations ◽  
Available Information

Duchenne muscular dystrophy (DMD) is a fatal X-linked recessive condition caused primarily by out-of-frame mutations in the dystrophin gene. In males, DMD presents with progressive body-wide muscle deterioration, culminating in death as a result of cardiac or respiratory failure. A milder form of DMD exists, called Becker muscular dystrophy (BMD), which is typically caused by in-frame dystrophin gene mutations. It should be emphasized that DMD and BMD are not exclusive to males, as some female dystrophin mutation carriers do present with similar symptoms, generally at reduced levels of severity. Cardiac involvement in particular is a pressing concern among manifesting females, as it may develop into serious heart failure or could predispose them to certain risks during pregnancy or daily life activities. It is known that about 8% of carriers present with dilated cardiomyopathy, though it may vary from 0% to 16.7%, depending on if the carrier is classified as having DMD or BMD. Understanding the genetic and molecular mechanisms underlying cardiac manifestations in dystrophin-deficient females is therefore of critical importance. In this article, we review available information from the literature on this subject, as well as discuss the implications of female carrier studies on the development of therapies aiming to increase dystrophin levels in the heart.

Pharmacological rescue of the dystrophin-glycoprotein complex in Duchenne and Becker skeletal muscle explants by proteasome inhibitor treatment

2006 ◽  
Vol 290 (2) ◽  
pp. C577-C582 ◽  
Author(s):  
Stefania Assereto ◽  
Silvia Stringara ◽  
Federica Sotgia ◽  
Gloria Bonuccelli ◽  
Aldobrando Broccolini ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscular Dystrophy ◽  
Proteasome Inhibitor ◽  
Becker Muscular Dystrophy ◽  
Culture Conditions ◽  
Mdx Mouse ◽  
Glycoprotein Complex ◽  
Dystrophin Glycoprotein Complex ◽  
Novel Method ◽  
Dystrophin Glycoprotein

In this report, we have developed a novel method to identify compounds that rescue the dystrophin-glycoprotein complex (DGC) in patients with Duchenne or Becker muscular dystrophy. Briefly, freshly isolated skeletal muscle biopsies (termed skeletal muscle explants) from patients with Duchenne or Becker muscular dystrophy were maintained under defined cell culture conditions for a 24-h period in the absence or presence of a specific candidate compound. Using this approach, we have demonstrated that treatment with a well-characterized proteasome inhibitor, MG-132, is sufficient to rescue the expression of dystrophin, β-dystroglycan, and α-sarcoglycan in skeletal muscle explants from patients with Duchenne or Becker muscular dystrophy. These data are consistent with our previous findings regarding systemic treatment with MG-132 in a dystrophin-deficient mdx mouse model (Bonuccelli G, Sotgia F, Schubert W, Park D, Frank PG, Woodman SE, Insabato L, Cammer M, Minetti C, and Lisanti MP. Am J Pathol 163: 1663–1675, 2003). Our present results may have important new implications for the possible pharmacological treatment of Duchenne or Becker muscular dystrophy in humans.

scholarly journals Sensitivity and Frequencies of Dystrophin Gene Mutations in Thai DMD/BMD Patients As Detected by Multiplex PCR

2008 ◽  
Vol 25 (2) ◽  
pp. 115-121 ◽  
Author(s):  
Thanyachai Sura ◽  
Jakris Eu-ahsunthornwattana ◽  
Sarinee Pingsuthiwong ◽  
Manisa Busabaratana
Keyword(s):  
Muscular Dystrophy ◽  
Multiplex Pcr ◽  
Gene Mutations ◽  
Dystrophin Gene ◽  
Index Patient ◽  
Becker Muscular Dystrophy ◽  
Large Size ◽  
Different Populations ◽  
The Mean ◽  
Deletion Frequency

Background: Duchenne muscular dystrophy (DMD), a lethal X-linked disease affecting 1 in 3500 male births, and its more benign variant, Becker muscular dystrophy (BMD), are caused by mutations in the dystrophin gene. Because of its large size, analysing the whole gene is impractical. Methods have been developed to detect the commonest mutations i.e. the deletions of the exons. Although these tests are highly specific, their sensitivity is inherently limited by the prevalence of deletions, which differs among different populations.Methods: We reviewed our database for the detection of Dystrophin gene mutation by means of 31-exon multiplex PCR in Thai males, diagnosed clinically and biochemically with DMD or BMD from July 1994 to November 2006. One index patient was chosen from each family for statistical analysis. The overall sensitivity of the test, the number of fragment deleted, and the deletion frequency of each fragment were calculated, along with their 95% confidence intervals (C.I.).Results: We found deletions in 99 out of the 202 index patients (49%; Bayesian 95% C.I. = 42%–56%). 51% of these had deletion in only one of the 31 exons tested, while the patient with the most extensive deletions had 14 exons deleted. The mean number of deleted exons were 2.84 (BCabootstrap 95% C.I. = 2.37–3.48), or 5.02 (3.81–6.85) if all the untested exons adjacent to the confirmed deleted exons were assumed to be deleted. The region spanning exons 44-52 was the most frequently deleted. These were similar to those reported in the Japanese.Conclusion: The multiplex PCR detected deletions only in about half of the Thai patients. The diseases therefore should not be excluded solely on the negative result if DMD/BMD is strongly suspected.

scholarly journals Analysis of duplications versus deletions in the dystrophin gene in Serbian cohort with dystrophinopathies

2020 ◽  
Vol 77 (4) ◽  
pp. 387-394
Author(s):  
Jasmina Maksic ◽  
Valerija Dobricic ◽  
Lukas Rasulic ◽  
Nela Maksimovic ◽  
Marija Branakovic ◽  
...  
Keyword(s):  
Muscular Dystrophy ◽  
De Novo ◽  
Dystrophin Gene ◽  
Becker Muscular Dystrophy ◽  
Severe Form ◽  
De Novo Mutation ◽  
Carrier Status ◽  
Phenotypic Effect ◽  
Exon 2 ◽  
Large Deletions

Background/Aim. Duchenne muscular dystrophy (DMD) and its allelic form Becker muscular dystrophy (BMD) are X-linked diseases that affect males, characterized by progressive muscle and cardiopulmonary weakness, especially in DMD as a severe form of the disease. They result from mutations in the dystrophin gene, and the most common changes are large intragenic deletions and duplications (80%). One third of patients have de novo mutation and 2/3 of the mothers are estimated as carriers. The aim of the study was to analyze the frequency of duplications versus deletions in the dystrophin gene in patients with dystrophinopathies, as well as to analyze the phenotypic effect of large mutations obtained and to determine the carrier status of female relatives in probands with duplications. Methods. We examined 22 DMD and 35 BMD unrelated patients and 6 female relatives of the probands where duplications were found. We used polymerase chain reaction (PCR) and multiplex ligation-dependent probe amplification (MLPA) methods, according to the protocol, to detect or confirm mutations in probands and female carriers. Results. In probands, there were 34 (59.6%) large deletions (mostly affected exons 44?60) and 6 (10.5%) large duplications in 4 DMD and 2 BMD patients. Also, duplications were found in 3 out of 4 (75%) tested mothers. The distribution of duplications was heterogeneous, affecting N-terminal and central rod domain, and included more exons, except for one DMD patient who had duplication of exon 2. An exception from the Monaco rule was present in 9.5% of DMD and 15.8% of BMD probands, i.e. in 12.5% of DMD/BMD cases. Conclusion. In 57 DMD/BMD probands, we found 59.6% of large deletions and 10.5% of large duplications. The most affected region of the DMD gene was the central rod domain. An exception to Monaco''s rule was present in 12.5% of DMD/BMD cases. Three out of 4 examined proband''s mothers were confirmed as carriers.

scholarly journals Unexpected DMD Gene Mutations Detected by CMA and CNV-seq in amniotic Fluid and Aborted Fetus Samples

2021 ◽  
Author(s):  
Qiuhua Wu ◽  
Lihui Yang ◽  
Qiujie Jin ◽  
Rui Wang ◽  
Wen Zhai ◽  
...  
Keyword(s):  
Prenatal Diagnosis ◽  
Muscular Dystrophy ◽  
Amniotic Fluid ◽  
Spontaneous Abortion ◽  
Gene Mutations ◽  
Dystrophin Gene ◽  
Becker Muscular Dystrophy ◽  
Hereditary Diseases ◽  
Muscle Dysfunction ◽  
Dmd Gene

Abstract Background: Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are common X chromosome-linked recessive hereditary diseases. The mechanism is that the exon mutations of anti-myatrophy protein gene (Dystrophin gene) and lead to muscle dysfunction. Prenatal diagnosis can prevent the birth of children with defects and have good clinical significance. Methods: CMA and CNV-seq were used to detect the amniotic fluid after amniocentesis,. CNV-seq was used to detect spontaneous abortion tissue. The DMD gene mutations were found in 6 amniotic fluid samples and one spontaneous abortion sample. DMD gene mutations were confirmed by MLPA and new DMD mutations were found.Results: CMA found DMD mutations :1.Xp21.1, 75.5kb del (E52-53); 2.Xp21.2, 334.92kb dup (E61-79); 3.Xp21.2, 292.25kb dup (E58-74); 4.Xp21.1, 374.20 kb dup (E45-51). CNV-seq found DMD mutations: 5.X p21.2, E64-79 dup; 6.X p21.1, E1-7dup; 7.Xp21.1, E 44-52 del. Conclusions: 4 fetuses harboring DMD gene mutations were found by CMA, 2 fetuses and 1 induced abortion carrying DMD gene mutations was detected by CNV-seq. CMA/CNV-seq jointed with MLPA test can provide more comprehensive evidence for prenatal diagnosis.

scholarly journals Sarcospan reduces dystrophic pathology: stabilization of the utrophin–glycoprotein complex

2008 ◽  
Vol 183 (3) ◽  
pp. 419-427 ◽  
Author(s):  
Angela K. Peter ◽  
Jamie L. Marshall ◽  
Rachelle H. Crosbie
Keyword(s):  
Muscular Dystrophy ◽  
Dystrophin Gene ◽  
Muscular Dystrophies ◽  
Mdx Mice ◽  
Future Design ◽  
Glycoprotein Complex ◽  
Analogous Complex ◽  
Dystrophin Glycoprotein Complex ◽  
Extrasynaptic Membrane ◽  
Dystrophin Glycoprotein

Mutations in the dystrophin gene cause Duchenne muscular dystrophy and result in the loss of dystrophin and the entire dystrophin–glycoprotein complex (DGC) from the sarcolemma. We show that sarcospan (SSPN), a unique tetraspanin-like component of the DGC, ameliorates muscular dystrophy in dystrophin-deficient mdx mice. SSPN stabilizes the sarcolemma by increasing levels of the utrophin–glycoprotein complex (UGC) at the extrasynaptic membrane to compensate for the loss of dystrophin. Utrophin is normally restricted to the neuromuscular junction, where it replaces dystrophin to form a functionally analogous complex. SSPN directly interacts with the UGC and functions to stabilize utrophin protein without increasing utrophin transcription. These findings reveal the importance of protein stability in the prevention of muscular dystrophy and may impact the future design of therapeutics for muscular dystrophies.

scholarly journals Autophagy in the heart is enhanced and independent of disease progression in mus musculus dystrophinopathy models

2019 ◽  
Vol 8 ◽  
pp. 204800401987958
Author(s):  
HR Spaulding ◽  
C Ballmann ◽  
JC Quindry ◽  
MB Hudson ◽  
JT Selsby
Keyword(s):  
Skeletal Muscle ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Disease Progression ◽  
Gene Mutations ◽  
Dystrophin Gene ◽  
Mdx Mice ◽  
Dystrophin Deficiency ◽  
Muscle Wasting Disease ◽  
Dystrophin Protein

Background Duchenne muscular dystrophy is a muscle wasting disease caused by dystrophin gene mutations resulting in dysfunctional dystrophin protein. Autophagy, a proteolytic process, is impaired in dystrophic skeletal muscle though little is known about the effect of dystrophin deficiency on autophagy in cardiac muscle. We hypothesized that with disease progression autophagy would become increasingly dysfunctional based upon indirect autophagic markers. Methods Markers of autophagy were measured by western blot in 7-week-old and 17-month-old control (C57) and dystrophic (mdx) hearts. Results Counter to our hypothesis, markers of autophagy were similar between groups. Given these surprising results, two independent experiments were conducted using 14-month-old mdx mice or 10-month-old mdx/Utrn± mice, a more severe model of Duchenne muscular dystrophy. Data from these animals suggest increased autophagosome degradation. Conclusion Together these data suggest that autophagy is not impaired in the dystrophic myocardium as it is in dystrophic skeletal muscle and that disease progression and related injury is independent of autophagic dysfunction.

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