UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase in nuclei and rimmed vacuoles of muscle fibers in DMRV (distal myopathy with rimmed vacuoles).
BACKGROUND
UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) is a key molecule in the pathogenesis of distal myopathy with rimmed vacuoles (DMRV) and hereditary inclusion body myopathy (HIBM) and almost all such patients have some mutations in GNE. However, subcellular localization of GNE and the mechanism of muscular damage have not been clarified.


METHODS
A rabbit polyclonal antibody for GNE was prepared. Immunohistochemistry was performed using anti-GNE and anti-nuclear protein antibodies. Western blotting with subcellular fractionated proteins was performed to determine subcellular localization of GNE. The sizes of myonuclei were quantified in muscle biopsies from patients with DMRV and amyotrophic lateral sclerosis (ALS).


RESULTS
In DMRV muscles, immunohistochemistry identified GNE in sarcoplasm and specifically in myonuclei and rimmed vacuoles (RV). Nuclear proteins were also found in RVs. Immunohistochemistry showed colocalization of GNE and emerin in C2C12 cells. Western blotting revealed the presence of GNE in nuclear fractions of human embryonic kidney (HEK) 293T cells. The mean size of myonuclei of DMRV was significantly larger than that of ALS.


CONCLUSIONS
GNE is present in myonuclei near nuclear membrane. Our results suggest that myonuclei are involved in RV formation in DMRV, and that mutant GNE in myonuclei seems to play some role in this process.
Department of Neurology and Neurological Science, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
Shoichiro
S
Ishihara
Hiroyuki
H
Tomimitsu
Hiroto
H
Fujigasaki
Fumiaki
F
Saito
Hidehiro
H
Mizusawa
D044466:Asian People / Q000235:genetics; D015153:Blotting, Western; D002238:Carbohydrate Epimerases / Q000235:genetics; D002467:Cell Nucleus / Q000201:enzymology / Q000473:pathology; D002478:Cells, Cultured; D049310:Distal Myopathies / Q000201:enzymology* / Q000235:genetics* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D007564:Japan; D008565:Membrane Proteins / Q000032:analysis; D009132:Muscles / Q000201:enzymology; D018979:Myositis, Inclusion Body / Q000201:enzymology / Q000235:genetics; D009687:Nuclear Proteins / Q000032:analysis; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D012519:Sarcoplasmic Reticulum / Q000201:enzymology; D014617:Vacuoles / Q000201:enzymology* / Q000473:pathology
D008565:Membrane Proteins; D009687:Nuclear Proteins; C092710:emerin; D017853:Phosphotransferases (Alcohol Group Acceptor); C018765:N-acylmannosamine kinase; D002238:Carbohydrate Epimerases; C100033:UDP acetylglucosamine-2-epimerase