Comparative Gene Expression Analysis in the Skeletal Muscles of Dysferlin-deficient SJL/J and A/J Mice

Abstract

Quantitative real-time polymerase chain reaction (qRT-PCR) analysis was conducted to determine whether or not there are interstrain or site-dependent differences in the gene expression profiles of skeletal muscles in SJL/J and A/J mice as dysferlinopathy models. Upon analysis by qRT-PCR, SJL/J mice showed a trend of increased gene expression level of uncoupling protein 2 in the rectus femoris and longissimus lumborum at 30 weeks of age when dystrophic lesions became histopathologically pronounced. Heme oxygenase 1 and S100 calcium binding protein A4 were upregulated in the rectus femoris, longissimus lumborum and abdominal muscles, in which dystrophic lesions occur more commonly in SJL mice. The gene expression levels of heat shock protein 70 in most muscles of A/J mice were lower than those of BALB/c mice as control. SJL/J mice exhibited a marked lowering of decay-accelerating factor 1/CD55 gene expression level in all studied muscles except for the heart at all ages compared with that of BALB/c mice. This study showed that there were some interstrain differences in the gene expres sion profiles of skeletal muscles between SJL/J and A/J mice. Further investigation is required to reveal whether these alterations of the expression levels are the cause of dystrophic changes or occur subsequent to muscle damage.

Keywords: A/J mouse; SJL/J mouse; decay-accelerating factor; dysferlin; heat shock protein; heme oxygenase-1.

Fig. 1.

Histopathology of the rectus femoris in BALB/c, SJL/J and A/J mice. At 10 weeks of age (upper figures), no significant changes are observed in the skeletal muscle fibers of BALB/c (A) and A/J mice (C), and a few muscle fibers show minimal degeneration with mono-nuclear cell infiltration in SJL/J mice (B). At 30 weeks of age (lower figures), BALB/c mice do not exhibit histopathological changes in any skeletal muscles (D). The histopathological lesions of skeletal muscles in SJL/J mice progress in severity with age and are characterized by the following findings: degenerative/necrotic muscle fibers, centronuclear muscle fibers, fatty infiltration and variation in size of muscle fibers (E). The muscle fibers in A/J mice show only degenerative/necrotic features and variation in size (F). HE staining. Bar: 100 µm.

Fig. 2.

The changes of principal genes in each muscle site of BALB/c, SJL/J and A/J mice. The presented genes (Ucp2, Hmox1, Hsp70, S100A4 and Daf1/CD55) are those for which the changes are suspected of involvement in muscular lesions observed in SJL/J and A/J mice. The severity of muscular lesions is as follows: lumbar muscle (longissimus lumborum) > femoral muscle (rectus femoris) > abdominal muscle > brachial muscle (triceps brachii) > crural muscle (gastrocnemius) > forearm muscle (flexor carpi ulnaris) > diaphragm. Ucp2 gene expression in the rectus femoris and longissimus lumborum of SJL/J mice shows a tendency to be upregulated with age. Hmox1 gene expression in the rectus femoris and longissimus lumborum of SJL/J mice is upregulated at 30 weeks of age. Hsp70 gene expression levels in most muscles of A/J mice are lower at all ages. S100A4 gene expression in the rectus femoris, longissimus lumborum and abdominal muscles of SJL/J mice is upregulated at 30 weeks of age. Daf1/CD55 gene expression in all studied muscles except for the heart of SJL/J mice shows a marked downregulation at all ages.