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J. Cell Biol.,
Volume 142, Number 6, September 21, 1998 1461-1471
-Sarcoglycan-deficient Mice



* Howard Hughes Medical Institute, Department of Physiology and Biophysics and Department of Neurology, University of
Iowa College of Medicine, Iowa City, Iowa 52242-1101; Limb-girdle muscular dystrophy type 2D
(LGMD 2D) is an autosomal recessive disorder caused
by mutations in the
Department of Pathology and § Department of Obstetrics and
Gynecology, University of Iowa College of Medicine, Iowa City, Iowa 52242;
Department of Anatomy and Neurobiology,
Washington University School of Medicine, St. Louis, Missouri 63110; ¶ Department of Internal Medicine, University of
Iowa College of Medicine, Iowa City, Iowa 52242; and ** Institute of Gerontology, University of Michigan, Ann Arbor,
Michigan 48109
-sarcoglycan gene. To determine
how
-sarcoglycan deficiency leads to muscle fiber degeneration, we generated and analyzed
-sarcoglycan-
deficient mice. Sgca-null mice developed progressive
muscular dystrophy and, in contrast to other animal
models for muscular dystrophy, showed ongoing muscle necrosis with age, a hallmark of the human disease.
Sgca-null mice also revealed loss of sarcolemmal integrity, elevated serum levels of muscle enzymes, increased muscle masses, and changes in the generation
of absolute force. Molecular analysis of Sgca-null mice
demonstrated that the absence of
-sarcoglycan resulted in the complete loss of the sarcoglycan complex,
sarcospan, and a disruption of
-dystroglycan association with membranes. In contrast, no change in the expression of
-sarcoglycan (
-sarcoglycan homologue)
was observed. Recombinant
-sarcoglycan adenovirus injection into Sgca-deficient muscles restored the
sarcoglycan complex and sarcospan to the membrane.
We propose that the sarcoglycan-sarcospan complex is
requisite for stable association of
-dystroglycan with
the sarcolemma. The Sgca-deficient mice will be a valuable model for elucidating the pathogenesis of sarcoglycan deficient limb-girdle muscular dystrophies and for
the development of therapeutic strategies for this disease.
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