Research On The Expression Of Dystrophin, Utrophin And NNOS In Different Types Of Muscular Dystrophy

Background In European, the incidence rate of muscular dystrophy is 1/2000. This disease is characterized by long-term pathogenesis, high percentage of disability and poor prognosis. There are few studies on the diagnosis or therapy for this disease.Dystrophin is a skeletal protein which plays an important role in the integrity of muscular structure. The mutation of dystrophin gene leads to duchenne muscular dystrophy(DMD) or becker muscular dystrophy(BMD). Dystrophin-related protein(utrophin) is structurally homologous to dystrophin. While in regenerating fibers the expression of utrophin is abundant and important for the integrity of muscular structure, it is almost completely replaced by dystrophin in mature fibers.Researches had shown that the extent of muscular damage is improved as the expression of utrophin increased in the mature muscle in DMD. Neural nitric oxide synthase(n NOS) could increase the supply of oxygen in the process of muscle movement. In muscle structure n NOS is closely associated with dystrophin. New researches had shown that the abnormal expression of n NOS in muscle may be linked to the appearance of exercise intolerance. At home and abroad, studies on the expression of dystrophin, utrophin and n NOS are rarely reported. To understand the expression of these three proteins in different types of muscular dystrophy and explore the correlation between their expression and the severity of DMD, we conducted this study as below.Objective The purpose of this study was to explore the expression of dystrophin, utrophin and n NOS in different types of muscular dystrophy. Furthermore the correlations between their expression and the severity of DMD were analyzed, and the relationship among these three proteins was considered meanwhile.Methods1. From March 2013 to May 2016, a total of 26 patients with DMD, 7 patients with BMD, 10 patients with Limb-girdle muscular dystrophy(LGMD), 5 patients with Facioscapulohumeral muscular dystrophy(FSHD), 5 patients with Distal muscular dystrophy and 11 patients with Dystrophia myotonia(DM) were gathered in department of Neurology. The control group consisted of 21 patients with emergency trauma or normal muscular pathology. Immunofluorescence intensity gradations was used to evaluate the expression of these three proteins. The expression levels of these three proteins was compared in different groups.2. The following items were used to assess the severity of DMD, such as Hammersmith functional motor score(HFMS), the ages when the following symptoms occurred: first motor symptoms, difficulty walking stairs and unable to walk independently. The patients with DMD were divided into two groups, the completely absent group and the partially absent group, according to the fluorescence intensity gradations of dystrophin and n NOS, and were divided into three groups according to utrophin, the negative group, the slightly increased group and the significantly increased group. Differences in the severity items between different groups were calculated using Kruskal-Wallis Test.3. Correlations between different expression of dystrophin, utrophin and n NOS were analyzed by spearman’s rank correlation.Results1. The expression of these three proteins were compared in different types of muscular dystrophy Compared with controls, there was no significant difference in the expression of these three proteins in patients with LGMD, FSHD, Distal muscular dystrophy and DM. When compared with controls and other types of muscular dystrophy, there was a decreased expression of dystrophin and n NOS and an increased expression of utrophin in both DMD and BMD(P<0.002). And a more decreased expression of dystrophin was found in DMD than BMD(P<0.002).2. The disease items were analyzed between different groups according to the expression of these three proteins There was no significant difference in severity items between the two groups both according to dystrophin and n NOS. For utrophin, among the three groups: in significantly increased group an older ages were found when patients reached at the symptoms of difficulty walking stairs and unable to walk independently than the other two groups(P<0.05). No significant difference were found in other disease items among these three groups3. The correlations between the expression of these three proteins were analyzed in DMD There was a negative correlation between the expression of utrophin and dystrophin in patients(r=-0.598, P<0.05). But no exact correlation was found between the expressions of n NOS with both utrophin and dystrophin.Conclusions1. The expression of dystrophin, utrophin and n NOS was abnormal in both DMD and BMD, which may play an important role for the diagnosis and classification in muscular dystrophy.2. The increased expression of utrophin could delay the disease progression of DMD. While the expression of dystrophin and n NOS had no clear effect on the disease.3. The negative correlation between the expression of utrophin and dystrophin in DMD might suggest that the decrease expression of dystrophin may up-regulate the expression of utrophin.