Histological findings showed regular dystrophic features in the majority of the patients, with the presence of moth-eaten and whorled fibers
Histological findings showed regular dystrophic features in the majority of the patients, with the presence of moth-eaten and whorled fibers. through Western blot analysis, deficiency of calpain 3 and dystrophin bands was found in four and two patients, respectively. All the remaining proteins showed a similar pattern to normal controls. These results suggest that, in our population of LGMD2I patients, different mutations in the gene are associated with several secondary muscle protein reductions, and the deficiencies of 2-laminin and -DG on sections are prevalent, independently of mutation type or clinical VU6005649 severity. (J Histochem Cytochem 56:995C1001, 2008) gene result in muscular dystrophy (MD) phenotypes, which were identified in congenital MD Type 1C (MDC-1C) and Limb-Girdle MD Type 2I (LGMD2I) (Brockington et al. 2001a,b). Both MDC and LGMD2I are heterogeneous groups of autosomal recessively inherited muscle diseases. MDC is usually characterized by onset of symptoms within the first few months of life, and in the 1C form, patients never acquire ambulation. LGMD2I has a milder and variable course, with the age at onset varying from the first to the fourthCfifth decade of life and slower progression. In both conditions, serum creatine kinase is usually elevated and intelligence is usually preserved, although structural brain changes have been Rabbit polyclonal to HCLS1 detected in some patients with mutations (Topaloglu et al. 2003; Mercuri et al. 2006; Quijano-Roy et al. 2006). Components of the extracellular matrix, such as 2-laminin, integrin -7, and collagen VI, interact with most defective proteins responsible for MDC, whereas the defects responsible for the LGMD forms are largely associated with sarcolemmal proteins , , , and -sarcoglycans, caveolin, dysferlin, and sarcomeric proteins such as telethonin and myotilin (Brockington et al. 2002; Bushby and Beckmann 2003). Although MDC-1C and LGMD2I are allelic disorders, it became clear that, in addition to the clinical and pathological heterogeneity, they are also genetically diverse. Different types of mutation cause MDC-1C, whereas the majority of the LGMD2I patients already described carry a common C826A missense mutation in the gene (Mercuri et al. 2003; Wicklund and Hilton-Jones 2003; Brown et al. 2004). Although the function of FKRP is still unknown, it has been suggested that it might be involved in the glycosylation of -DG in muscle membrane. The DG complex is usually important in muscle formation and maintenance and cell adhesion, and it also plays an important role in the function of other tissues, such as brain, kidneys, and peripheral nerves. A single gene encodes a polypeptide that is post-translationally modified to yield the two glycoproteins referred to as – and -DG (Michele et al. 2002; Martin 2003; Cohn 2005). -DG is usually a heavily glycosylated peripheral membrane component of the dystrophin-associatedCglycoprotein complex (DGC), whereas -DG is usually a transmembrane protein that links to dystrophin intracellularly. The disruption of this linkage underlies several forms of MD, underscoring its importance in striated muscle, which contributes to the structural integrity of the sarcolemma (Ervasti and Campbell 1993). Providing evidence for the glycosyltransferase function of FKRP, patients with MDC-1C typically show abnormalities of -DG glycosylation, in addition to a secondary reduction in 2-laminin (Brockington et al. 2001b). All studied patients with this severe form had VU6005649 a variable secondary reduction in 2-laminin expression, which was less marked than the reduction in -DG (Brockington et al. 2002; Brown et al. 2004). Moreover, muscle biopsy findings seem to be less uniform in patients with LGMD2I. Analysis of muscle biopsies has shown variable secondary protein abnormalities, and unlike MDC-1C, detection of abnormal 2-laminin chain on IHC is not so remarkable (Poppe et al. 2003). Because FKRP protein cannot be easily measured, secondary effects on muscle protein presence and organization can be used as additional information on the mechanism of the disease and could explain the huge clinical variability observed among LGMD2I patients (de Paula et al. 2003). Here we report muscle biopsy analyses and the expression of muscle proteins of the sarcolemma (dystrophin, four sarcoglycans, dysferlin), extracellular matrix (2-laminin, -DG, collagen VI), sarcomere (telethonin), and cytosol (calpain 3) in 13 LGMD2I families with 10 different mutations in the gene. Materials and Methods Patients We analyzed 13 unrelated LGMD2I patients with different mutations in the gene (Table 1). These patients were molecularly selected and clinically classified in a previous study of 86 Brazilian families (de Paula et al. 2003), ascertained in the Human Genome Research Center, Department of Biology, IB-USP, and classified as LGMD according to the criteria reported in Bushby (1995) and Bushby and Beckmann (2003). VU6005649 The study was performed after receiving the Institutional Human Subjects Review Board (IRB) approval. All patients signed the.