Interferon-stimulated gene 15 (ISG15) conjugates proteins in dermatomyositis muscle with perifascicular atrophy.
OBJECTIVE
We investigated interferon-stimulated gene 15 (ISG15), a poorly understood ubiquitin-like modifier, and its enzymatic pathway in dermatomyositis (DM), an autoimmune disease primarily involving muscle and skin.


METHODS
We generated microarray data measuring transcript abundance for approximately 18,000 genes in each of 113 human muscle biopsy specimens, and studied biopsy specimens and cultured skeletal muscle using immunohistochemistry, immunoblotting proteomics, real-time quantitative polymerase chain reaction, and laser-capture microdissection.


RESULTS
Transcripts encoding ISG15-conjugation pathway proteins were markedly upregulated in DM with perifascicular atrophy (DM-PFA) muscle (ISG15 339-fold, HERC5 62-fold, and USP18 68-fold) compared with 99 non-DM samples. Combined analysis with publicly available microarray datasets showed that >50-fold ISG15 transcript elevation had 100% sensitivity and specificity for 28 biopsies from adult DM-PFA and juvenile DM patients compared with 199 muscle samples from other muscle diseases. Free ISG15 and ISG15-conjugated proteins were only found on immunoblots from DM-PFA muscle. Cultured human skeletal muscle exposed to type 1 interferons produced similar transcripts and ISG15 protein and conjugates. Laser-capture microdissection followed by proteomic analysis showed deficiency of titin in DM perifascicular atrophic myofibers.


CONCLUSIONS
A large-scale microarray study of muscle samples demonstrated that among a diverse group of muscle diseases DM was uniquely associated with upregulation of the ISG15 conjugation pathway. Exposure of human skeletal muscle cell culture to type 1 interferons produced a molecular picture highly similar to that seen in human DM muscle. Perifascicular atrophic myofibers in DM were deficient in a number of skeletal muscle proteins including titin.
Salajegheh
Mohammad
M
Children's Hospital Informatics Program, Division of Neuromuscular Disease, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Kong
Sek Won
SW
Pinkus
Jack L
JL
Walsh
Ronan J
RJ
Liao
Anne
A
Nazareno
Remedios
R
Amato
Anthony A
AA
Krastins
Bryan
B
Morehouse
Chris
C
Higgs
Brandon W
BW
Jallal
Bahija
B
Yao
Yihong
Y
Sarracino
David A
DA
Parker
Kenneth C
KC
Greenberg
Steven A
SA
D002478:Cells, Cultured; D064211:Connectin; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D030541:Databases, Genetic; D003882:Dermatomyositis / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007370:Interferon Type I / Q000378:metabolism; D007834:Lasers; D042282:Microdissection / Q000379:methods; D009124:Muscle Proteins / Q000172:deficiency; D018482:Muscle, Skeletal / Q000378:metabolism*; D009135:Muscular Diseases / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000172:deficiency; D040901:Proteomics / Q000379:methods; D012680:Sensitivity and Specificity; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
D064211:Connectin; D016207:Cytokines; D007370:Interferon Type I; D009124:Muscle Proteins; C577285:TTN protein, human; D014452:Ubiquitins; C074034:ISG15 protein, human; D011494:Protein Kinases