Muscular Dystrophy Of Chicken Research Articles

β-dystroglycan is regulated by a balance between WWP1-mediated degradation and protection from WWP1 by dystrophin and utrophin

Dystroglycan is a ubiquitous membrane protein that functions as a mechanical connection between the extracellular matrix and cytoskeleton. In skeletal muscle, dystroglycan plays an indispensable role in regulating muscle regeneration; a malfunction in dystroglycan is associated with muscular dystrophy. The regulation of dystroglycan stability is poorly understood. Here, we report that WWP1, a member of NEDD4 E3 ubiquitin ligase family, promotes ubiquitination and subsequent degradation of β-dystroglycan. Our results indicate that dystrophin and utrophin protect β-dystroglycan from WWP1-mediated degradation by competing with WWP1 for the shared binding site at the cytosolic tail of β-dystroglycan. In addition, we show that a missense mutation (arginine 440 to glutamine) in WWP1—which is known to cause muscular dystrophy in chickens—increases the ubiquitin ligase-mediated ubiquitination of both β-dystroglycan and WWP1. The R440Q missense mutation in WWP1 decreases HECT domain-mediated intramolecular interactions to relieve autoinhibition of the enzyme. Our results provide new insight into the regulation of β-dystroglycan degradation by WWP1 and other Nedd4 family members and improves our understanding of dystroglycan-related disorders.

The muscular dystrophic chicken is hypernatremic

ABSTRACT1. The E3 ubiquitin protein ligase 1 (WWP1) gene, the mutation of which causes muscular dystrophy in chickens, is expressed not only in the pectoral muscle, but also in a number of tissues such as the kidney. Therefore, this study examined some parameters related to kidney function in muscular dystrophic (MD) chickens.2. Plasma osmolality, Na+ and K+ concentrations, aldosterone levels, and the expression of aquaporin (AQP) 2, AQP3, and α subunits of the amiloride-sensitive epithelial sodium channel (αENaC) were analysed in the kidneys of 5-week-old MD chickens and White Leghorn (WL) chickens under physiological conditions or after one day of water deprivation.3. Plasma osmolality, Na+ concentrations, and plasma aldosterone levels were significantly higher in MD chickens than in WL chickens. αENaC mRNA expression levels were lower in MD chickens than in WL chickens. AQP2 and AQP3 mRNA expression levels were similar in the two strains of chickens.4. Plasma osmolality correlated with aldosterone levels and AQP2 and αENaC mRNA levels in WL chickens. In MD chickens, plasma osmolality correlated with AQP2 mRNA levels, but not with plasma aldosterone or αENaC mRNA levels.5. These results suggest that neither water reabsorption nor the expression of AQP2 and AQP3 is impaired in MD chickens and that a WWP1 gene mutation may or may not directly induce an abnormality in Na+-reabsorption in the kidneys of MD chickens, potentially through αENaC.

Selenium Deficiency Mainly Influences the Gene Expressions of Antioxidative Selenoproteins in Chicken Muscles

Dietary selenium (Se) deficiency induces muscular dystrophy in chicken, but the molecular mechanism remains unclear. The aim of the present study was to investigate the effect of dietary Se deficiency on the expressions of 25 selenoproteins. One-day-old broiler chickens were fed either an Se deficiency diet (0.033mg Se/kg; produced in the Se-deficient area of Heilongjiang, China) or a diet supplemented with Se (as sodium selenite) at 0.2mg/kg for 55days. Then, the mRNA levels of 25 selenoproteins in chicken muscles were examined, and the principal component was further analyzed. The results showed that antioxidative selenoproteins especially Gpxs and Sepw1 were highly and extensively expressed than other types of selenoproteins in chicken muscles. In 25 selenoproteins, Gpxs, Txnrd2, Txnrd 3, Dio1, Dio 3, Selk, Sels, Sepw1, Selh, Sep15, Selu, Selpb, Sepp1, Selo, Sepx1, and SPS2 were downregulated (P < 0.05), and other selenoproteins were not influenced (P > 0.05). Se deficiency decreased the expressions of 19 selenoproteins (P < 0.05), 11 of which were antioxidative selenoproteins. And, principal component analysis (PCA) further indicated that antioxidative selenoproteins, especially Gpx3, Gpx4, and Sepw1, may play crucial roles in chicken muscles. However, compared with these antioxidative selenoproteins, some other lower expressed selenoproteins (Dio1, Selu, Selpb, Sepp1) were excessively decreased (more than 60%, P < 0.05) by Se deficiency. Thus, it may save the limited Se levels and be beneficial to remain the level of some crucial selenoproteins. These results suggested that Se deficiency mainly influenced the expressions of antioxidative selenoproteins in chicken muscles. And, antioxidative selenoproteins especially Gpxs and Sepw1 may play a crucial role in chicken muscles. Thus, it helps us focus on some specific selenoproteins when studying the role of Se in chicken muscles.

Pinpointing the candidate region for muscular dystrophy in chickens with an abnormal muscle gene

ABSTRACTMuscular dystrophies, a group of inherited diseases with the progressive weakness and degeneration of skeletal muscle, contain genetically variable diseases. Though chicken muscular dystrophy with abnormal muscle (AM) has long been known, the gene responsible has not yet been identified. In this study, a resource family for AM was established with 487 F2 individuals and 22 gene markers, including microsatellite and insertion–deletion markers, were developed. The haplotypes were analyzed with these markers for the candidate region of GGA2q described in a previous study. The candidate region was successfully narrowed down to approximately 1Mbp. The region included seven functional genes predicted as the most likely AM candidates.

Thyroidal involvement in the expression of avian muscular dystrophy

We showed previously that propylthiouracil (PTU), a thyroid inhibitor, could alleviate several major signs of hereditary muscular dystrophy in chickens. The goals of the present investigation were to: (1) determine whether a nearly athyroid condition (achieved within two days after hatching by surgical thyroidectomy plus PTU) during an 11-day period beneficially affects the dystrophic condition when followed by triiodothyronine (T3) replacement to 33 days of age; (2) determine the beneficial effects on the expression of avian dystrophy when the thyroidectomized-PTU-treated chickens received a wide range of moderate to low T3 replacement doses beginning by two days after thyroidectomy; and (3) examine the thyroid hormone receptor system in dystrophic muscle for a possible abnormality. Thyroid deprivation increased muscle function (righting ability) and reduced plasma creatine kinase activity in dystrophic chickens. The major thyroid-related abnormality in dystrophic pectoralis muscles was an increased maximum binding capacity of solubilized nuclear T3 receptors.

Muscle Development and Muscular Dystrophy in Chicken

In developing skeletal muscle, both contractile and regulatory proteins are synthesized and assembled into myofibrillar structures, while in dystrophic muscles, they are gradually disassembled and the muscle contractile activity is substantially decreased. For the understanding of the myofibrillar disorganization, variation of myofibrillar proteins in the dystrophic muscle should be clarified. In this study, alteration of C-protein and troponin T (TNT) during muscle development and progression of muscular dystrophy was examined with chicken as a model animal. At embryonic stages, cardiac-type C-protein (Cc) was detected first and transiently in skeletal muscles. At neonatal ages, slow- (Cs) and fast type (Cf) C-proteins were coexpressed in the pectoralis muscle (PM) of both normal and dystrophic chicken, but Cs disappeared, leaving continued expression of only Cf as muscle development progressed up to 2 weeks posthatch. In the dystrophic chicken PM, however, myofiber containing Cs reappeared and increased in number with the progression of muscular dystrophy. C-Proteins were further examined by 2D-PAGE. Two variants of slow C-protein (Cs3 and Cs4) were detected in adult muscle tissues. C-Proteins in the neonatal PM were Cf and Cs3, but in dystrophic PM, both Cs3 and Cs4 were detected in addition to Cf. These results indicate that C-protein varies during development and also in the process of degeneration of chicken skeletal muscles, and in addition the dystrophic muscle differs from the neonatal muscle with regards to C-protein isoform expression. Troponin T also exhibited remarkable isoform change during muscle development. The neonatal and dystrophic PMs differed in TNT isoform pattern although they shared several common TNT isoforms. The author conclude that the dystrophic muscle resembles the neonatal muscle, but does not recapture simply the nature of the latter muscle, but shifts toward a somewhat different direction.

Sarcomere length in normal and dystrophic chick muscles

An electron microscope study of 2- and 8-week-old normal and dystrophic chickens compared sarcomere lengths in relaxed and passively extended Patagialis (PAT) muscles. Sarcomeres were measured in dystrophic muscles only in fibers which exhibited no morphological signs of degeneration. Sarcomere lengths were not different from each other in normal muscles of 2- and 8-week-old chickens. Passive extension of the normal wing increased mean sarcomere length by 44%. Sarcomere lengths in unstretched dystrophic PAT muscles were 22 and 25% longer than unstretched normal sarcomeres at 2 and 8 weeks of age. Passive extension of the wing further increased sarcomere length of 2-week-old dystrophic muscles to the length of stretched sarcomeres in 2-week-old normal muscles. In 8-week-old dystrophic chickens, the wings could be passively extended to only 134°, rather than the normal range of 180°. In this case, passive extension of the wings did not further increase the length of sarcomeres. Increased sarcomere lengths in dystrophic muscles may indicate that dystrophic muscle fibers are being subjected to greater degrees of passive tension than normal muscle fibers during early stages of growth. Passive tension is known to promote fiber hypertrophy, nuclear proliferation, and increased oxidative metabolism in normal muscle. These responses to passive tension are also characteristic of prenecrotic stages of muscular dystrophy in chickens.

Activities of antioxidant enzymes in muscle, liver and lung of chickens with inherited muscular dystrophy

An inherited form of muscular dystrophy in chickens has been used as a model of Duchenne muscular dystrophy. The pectoralis major muscle of chickens with this disease showed a significantly elevated activity of catalase (CAT) one day after hatching, and by 7 days showed elevated superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione-S-transferase (GST) activities. Increases were also found in tissues of the dystrophic birds that, unlike the pectoralis muscle, are considered to be unaffected by the pathology of muscular dystrophy. The soleus muscle contained significantly increased levels of SOD and GPX in 1 and 7 day old chickens, and increased GST in 1, 14, and 28 day old birds. CAT was significantly increased in liver from 1 and 7 day old chickens, while GPX was increased in lung from 1, 7 and 14 day old birds. These results support the possibility that excess oxygen free-radicals or altered cellular antioxidant defenses play some role in the pathogenesis of muscular dystrophy.

Sex differences in the phenotypic expression of avian dystrophy

Although the gene for muscular dystrophy in chickens is not sex-linked, results from clinical tests suggest that it is expressed differently in males and females. As measurement of muscle contractile responses provides a quantitative index for the severity of the disease, the contractile properties of the extensor digitorum communis muscle were examined in normal and dystrophic chickens with respect to sex. Furthermore, these differences were examined in young (6 to 9 weeks) and old (greater than 6 months) chickens. Results showed that age-related sex differences were apparent for those mechanical parameters of the muscle (in particular the posttetanic potentiation and posttetanic contracture) known to distinguish normal and dystrophic birds. The sex differences observed in the younger group indicate that the female birds were more severely affected by the disease than were the male. In the older group, the male were affected by the disease more severely than age-matched female birds. If the inheritance pattern is truly autosomal then it is likely that one or more developmental factors interact with the dystrophic genotype and alter the dystrophic phenotype.

Water deprivation: Beneficial effect on muscular dystrophy in chickens

Chicks affected with hereditary muscular dystrophy were deprived of water for 1 to 4 days at ages to 37 days ex ovo. Water deprivation partially alleviated impaired righting ability and reduced the typically elevated plasma creatine kinase activity by as much as 90%. Muscles from water-deprived chicks showed several qualitative histologic improvements, including decreased sarcoplasmic staining for acetylcholinesterase activity, reduced fiber diameters, and a decreased incidence of abnormally large rounded fibers, but retained the high degree of fiber diameter variability characteristic of dystrophic muscles. Feed deprivation reduced body weight to a similar extent as water deprivation but had lesser effects on creatine kinase activity and did not improve righting ability or muscle histology. Although the mechanism of the improvements is unknown, the magnitude and scope of the effects suggest that water deprivation beneficially alters a major abnormality in dystrophic chickens.

Early detection of inherited muscular dystrophy in chickens

New Hampshire chickens, homozygous for inherited muscular dystrophy, display clinical manifestations at an early age. A fine structural examination of embryos from this strain shows marked degenerative changes four days prior to hatching. The Z bands appear to dissolve progressively to the point where finally the myofibrils become uniformly dense with no detectable banding patterns.

Cholinomimetic teratogens. IV. Effects of the genotype for muscular dystrophy in chickens

Embryos of a family of chickens homozygous for muscular dystrophy (md/md) reacted with a higher incidence of malformations to treatment with carbachol than did White Leghorn embryos. The same difference in response of embryos from the two stocks occurred after treatment with sulfanilamide. Embryos of reciprocal crosses between these two stocks differed greatly, however, in their response to carbachol, F1 embryos from dystrophic hens producing a much higher incidence of malformations than did those from Leghorn hens. In contrast, both F1 sibs reacted similarly to sulfanilamide, the teratogenic effects being intermediate between those of embryos from the parent stocks.

Postponement of symptoms of hereditary muscular dystrophy in chickens by 5-hydroxytryptamine antagonists.

THE commoner forms of muscular dystrophy, both in man and in animals, are determined by a single gene change, but the mechanism whereby the complex set of symptoms develops is unknown. Chickens homozygous for muscular dystrophy have been bred, and form probably the closest animal model for the human disease so far investigated1,2. Dystrophic line 304 of the Davis (California) flock, for example, has been bred for rapid appearance of the symptoms and shows some signs of muscle weakness at 7–10 d ex ovo, whereas a normal line (200) of chickens with closely related genetic background is also available1,2. Two of us have reviewed3 evidence that 5-hydroxytryptamine (5-HT) is involved in some way in the development of the symptoms of muscular dystrophy, and reported that administration of a 5-HT antagonist, methysergide, retards the development of the symptoms in line 304 chickens. We report here that this effect is more general, in that a second anti-serotoninergic drug of entirely different chemical structure, cyproheptadine, is also effective, and that a combination of the two agents is beneficial.

Beneficial effects of penicillamine treatment on hereditary avian muscular dystrophy.

Hereditary muscular dystrophy in chickens of the New Hampshire strain was treated with penicillamine from the 9th day after hatching to the 425th day. The adult maintenance dose for males was 50 mg/kg per day and for females, 13-65 mg/kg per day. In avian dystrophy, deterioration of the muscle fibers is evidenced in the 2nd mo by an inability of the birds to rise after falling on their backs and by a progressive rigidity of the wings. The drug delayed the onset of symptoms and partially alleviated the debilitating aspects of the disease. Penicillamine produced three major improvements: (a) better righting ability when birds were placed on their backs; (b) greater wing flexibility; (c) and suppression of plasma creatine phosphokinase activity. The results are statistically analyzed and discussed in relationship to Duchenne dystrophy. Normal birds were not affected by penicillamine as judged by these parameters. The rationale for using penicillamine, a sulfhydryl compound with reducing properties, was (a) to attempt to protect essential thiol enzymes in the anabolic and glycolytic pathways against inactivation and (b) to prevent collagen cross-linking and deposition in muscle. Although the precise mechanism of drug action has not been determined. the possible role of penicillamine in mitigating the symptoms of genetic dystrophy in man is under consideration. Further, penicillamine may have a more generalized application i the prevention of contractures in a variety of neuromuscular disorders.

Tenderness of Dystrophic Chicken Meat

THE occurrence of muscular dystrophy in chickens has been traced to an autosomal recessive gene (Asmundson and Julian, 1956, 1963). Several studies have been made at the University of California at Davis on the composition of the dystrophic chicken muscle (Jordan et al., 1959., 1964; Peterson et al., 1963; and Wilson et al., 1965). Fat content of the Pectoralis superficialis of dystrophic chickens increased abnormally as early as 15 weeks of age, and exceeded 20% by 78 weeks, compared to 1–2% for normal controls. Taurine and serine-ethanolamine-phosphate content of adult dystrophic chicken Pectoralis superficialis was more than 10 fold that of controls, and carnosine and anserine levels were less. The present report provides data on the relative tenderness of cooked dystrophic and normal muscle, corresponding values for the fat content and pH, and certain characteristics of the carcasses.A sample of 23 dystrophic [10 males, 13 females (Univ. of .