Expression of Dp71 in Müller glial cells: a comparison with utrophin- and dystrophin-associated proteins.
OBJECTIVE
The abnormal retinal electrophysiology observed in patients with Duchenne muscular dystrophy (DMD) has been attributed to an altered expression of C-terminal products of the dystrophin gene. It has been shown that Dp260 is expressed by photoreceptor cells, whereas Dp71 is present in glial cells. The present study was intended to identify all known members of the dystrophin superfamily and their associated proteins expressed in Müller glial cells (MGC).


METHODS
The expression of the proteins and of their messengers was studied in MGC cultures from 2-week-old rats, by polymerase chain reaction amplification, Western blot analysis, and immunocytochemistry. An immunocytochemical localization of the proteins was also performed on enzymatically dissociated Müller cells from adult rat retinas.


RESULTS
MGCs expressed a spliced isoform of Dp71 called Dp71f, as well as utrophin, beta-dystroglycan, delta and gamma-sarcoglycans, and alpha1-syntrophin. In morphologically preserved differentiated Müller cells, Dp71f was localized in clusters, utrophin was diffusely distributed in the cytoplasm, and dystrophin-associated proteins (DAPs) were membrane-bound. Most of these proteins were preferentially expressed in the vitread portion of the cells. Dp71f and utrophin expression was restricted to MGCs, whereas all DAPs were also present in other retinal cell types.


CONCLUSIONS
The exclusive localization of Dp71f and utrophin in MGCs suggests that these proteins, together with DAPs, play a specific role in these cells. Further knowledge of possible interactions of these proteins within a functional complex may provide new insights into the molecular basis of the electroretinogram phenotype in DMD.
Claudepierre
T
T
Institute Nationale de la Santé et de la Recherche Médicale (INSERM) EMI 99-18, Laboratoire de Physiopathologie Cellulaire et Moléculaire de la Rétine, Médicale A, CHRU, Strasbourg, France.
Mornet
D
D
Pannicke
T
T
Forster
V
V
Dalloz
C
C
Bolaños
F
F
Sahel
J
J
Reichenbach
A
A
Rendon
A
A
D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000096:biosynthesis / Q000235:genetics*; D017931:DNA Primers / Q000737:chemistry; D016189:Dystrophin / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000096:biosynthesis / Q000235:genetics*; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D009457:Neuroglia / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D049411:Utrophin
D003598:Cytoskeletal Proteins; D017931:DNA Primers; D016189:Dystrophin; D005136:Eye Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D049411:Utrophin; C085339:apo-dystrophin 1