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Expression of Dp71 in Müller glial cells: a comparison with utrophin- and dystrophin-associated proteins
T Claudepierre1, D Mornet, T Pannicke
1Institute 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.
Purpose:
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.
Insights
Müller glial cells (MGCs) in rats express Dp71f and utrophin, suggesting a specific role in retinal function. These findings may explain electroretinogram abnormalities in Duchenne muscular dystrophy (DMD).
Area of Science:
- Neuroscience
- Cell Biology
- Ophthalmology
Background:
- Abnormal retinal electrophysiology in Duchenne muscular dystrophy (DMD) is linked to altered dystrophin gene expression.
- Dp260 is found in photoreceptor cells, while Dp71 is in glial cells.
Purpose of the Study:
- To identify all known dystrophin superfamily members and associated proteins expressed in Müller glial cells (MGCs).
- To investigate the specific roles of these proteins within MGCs.
Main Methods:
- Cultured MGCs from 2-week-old rats were analyzed using polymerase chain reaction, Western blot, and immunocytochemistry.
- Immunocytochemical localization was performed on enzymatically dissociated Müller cells from adult rat retinas.
Main Results:
- MGCs express Dp71f, utrophin, beta-dystroglycan, delta and gamma-sarcoglycans, and alpha1-syntrophin.
- Dp71f and utrophin showed restricted expression to MGCs, while dystrophin-associated proteins (DAPs) were also found in other retinal cells.
- Dp71f localized to clusters, utrophin diffusely in the cytoplasm, and DAPs were membrane-bound within MGCs.
Conclusions:
- The exclusive localization of Dp71f and utrophin in MGCs indicates a specific function for these proteins in these cells.
- Understanding the interactions of these proteins may elucidate the molecular basis of the electroretinogram phenotype in DMD.