11 research outputs found
Reduced expression of sarcospan in muscles of Fukuyama congenital muscular dystrophy
Summary. Expression profiles of sarcospan in muscles
with muscular dystrophies are scarcely reported. To
examine this, we studied five Fukuyama congenital
muscular dystrophy (FCMD) muscles, five Duchenne
muscular dystrophy (DMD) muscles, five disease
control and five normal control muscles. Immunoblot
showed reactions of sarcospan markedly decreased in
FCMD and DMD muscle extracts. Immunohistochemistry of FCMD muscles showed that most large
diameter myofibers expressed sarcospan discontinuously
at their surface membranes. Immature small diameter
FCMD myofibers usually did not express sarcospan.
Immunoreactivity of sarcospan in DMD muscles was
similarly reduced. With regard to dystroglycans and
sarcoglycans, immunohistochemistry of FCMD muscles
showed selective deficiency of glycosylated α-
dystroglycan, together with reduced expression of ß-
dystroglycan and α-, ß-, γ-, δ-sarcoglycans. Although the
expression of glycosylated α-dystroglycan was lost,
scattered FCMD myofibers showed positive
immunoreaction with an antibody against the core
protein of α-dystroglycan. The group mean ratios of
sarcospan mRNA copy number versus GAPDH mRNA
copy number by real-time RT-PCR showed that the
ratios between FCMD and normal control groups were
not significantly different (P>0.1 by the two-tailed t
test). This study implied either O-linked glycosylation
defects of α-dystroglycan in the Golgi apparatus of
FCMD muscles may lead to decreased expression of
sarcoglycan and sarcospan molecules, or selective
deficiency of glycosylated α-dystroglycan due to
impaired glycosylation in FCMD muscles may affect the
molecular integrity of the basal lamina of myofibers. This, in turn, leads to decreased expression of
sarcoglycans, and finally of sarcospan at the FCMD
myofiber surfaces