Alternative splicing factor ASF/SF2 is down regulated in inflamed muscle.
BACKGROUND
In our recent studies, alternative splicing has been shown to have a major role in inflammation and autoimmune muscle diseases.


OBJECTIVE
To examine the novel hypothesis that the expression of an essential alternative splicing factor, alternative splicing factor 2 (ASF/SF2), is modulated in muscle inflammation.


METHODS
ASF/SF2 expression in muscle biopsy samples from eight patients with inflammatory myopathy and six non-myositic controls was determined by using western blot with anti-ASF/SF2 antibodies. To further elucidate the mechanism of reduced ASF/SF2 expression in inflamed muscle, differentiated C2C12 myotubes were stimulated with proinflammatory cytokine tumour necrosis factor alpha (TNFalpha), followed by western blot analysis of ASF/SF2 expression.


RESULTS
ASF/SF2 expression in the muscle biopsy samples from patients with inflammatory myopathy was found to be lower (mean of relative densitometric units 41.1 (2SD 20.7)) than that of the non-myositic controls (mean of relative densitometric units 76.7 (39.6); p<0.05). In addition to this, ASF/SF2 expression was seen to be significantly down regulated (sevenfold) in C2C12 myotubes compared with expression variations in the beta-actin control (0.62-fold; mean 1.22 (0.40); p<0.05).


CONCLUSIONS
Collectively, it is shown, for the first time, that alternative splicing factor ASF/SF2 is down regulated in autoimmune inflammatory myositis-potentially via a TNFalpha-mediated pathway. The development of (1) novel autoantigen isoform microarrays for disease diagnosis and prognosis; (2) novel autoantigen-tolerising treatments for autoimmune diseases; and (3) novel splicing-redirection treatments can be facilitated by the ongoing study of alternative splicing of autoantigen transcripts.
Xiong
Z
Z
Laboratory of Immunopathology, Department of Pharmacology, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
Shaibani
A
A
Li
Y-P
YP
Yan
Y
Y
Zhang
S
S
Yang
Y
Y
Yang
F
F
Wang
H
H
Yang
X-F
XF
D000368:Aged; D000369:Aged, 80 and over; D017398:Alternative Splicing; D000818:Animals; D001327:Autoimmune Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D001706:Biopsy; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009220:Myositis / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D014409:Tumor Necrosis Factor-alpha; D000068103:Serine-Arginine Splicing Factors