Expression of the lysosome-associated membrane proteins in myopathies withrimmed vacuoles

Citation
Y. Tsuruta et al., Expression of the lysosome-associated membrane proteins in myopathies withrimmed vacuoles, ACT NEUROP, 101(6), 2001, pp. 579-584
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences & Behavoir
Journal title
ACTA NEUROPATHOLOGICA
ISSN journal
0001-6322 → ACNP
Volume
101
Issue
6
Year of publication
2001
Pages
579 - 584
Database
ISI
SICI code
0001-6322(200106)101:6<579:EOTLMP>2.0.ZU;2-8
Abstract
Lysosome-associated membrane proteins (LAMPs) are structural glycoproteins located on the lysosomal membrane and are thought to have an important role in protein degradation. Increased lysosomal activity is associated with th e formation of rimmed vacuoles, which are observed in various muscle disord ers such as inclusion body myositis (IBM) and distal. myopathy with rimmed vacuole (DMRV). In the present study, we examined LAMP-1 and LAMP-2 in biop sied muscle specimens from four cases of sporadic IBM and two of DMRV, as w ell as six of myopathies without rimmed vacuoles. In all cases of IBM and D MRV, immunohistochemistry showed accumulation of LAMPs in the rimmed vacuol es and the subsarcolemmal portion of the vacuolated fibers. Immunoreactivit ies of LAMPs in the vacuolated fibers were often associated with those of c athepsin D; however, cathepsin D was not expressed on some LAMP-positive fi bers. Further, atrophic muscle fibers were sometimes positive for LAMPs exp ression. These findings were more prominent in LAMP-2 than in LAMP-1. Thus, LAMP-2 may play an important role in the increased protein degradation in diseased muscle fibers. The increased expression of LAMPs in the vacuolated muscle fibers may be associated with the formation of rimmed vacuoles in I BM and DMRV.