April 2011
Volume 52, Issue 14
ARVO Annual Meeting Abstract  |   April 2011
Myocilin Interacts With Syntrophins And Is A Member Of The Dystrophin-Associated Protein Complex
Author Affiliations & Notes
  • Myung Kuk Joe
    National Eye Institute, Bethesda, Maryland
  • Changwon Kee
    Ophthalmology, Samsung Med Ctr, SKK Univ, Seoul, Republic of Korea
  • Stanislav I. Tomarev
    SMMG, LMDB, National Eye Institute, Rockville, Maryland
  • Footnotes
    Commercial Relationships  Myung Kuk Joe, None; Changwon Kee, None; Stanislav I. Tomarev, None
  • Footnotes
    Support  Intramural Research Program of the National Institutes of Health
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 4646. doi:
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      Myung Kuk Joe, Changwon Kee, Stanislav I. Tomarev; Myocilin Interacts With Syntrophins And Is A Member Of The Dystrophin-Associated Protein Complex. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4646.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose: : MYOCILIN, a causative gene for open-angle glaucoma, encodes a secreted glycoprotein of unknown function. Previously, we identified α1-syntrophin, a component of the dystrophin-associated protein complex (DAPC) as a myocilin-binding partner through a yeast two-hybrid screen. To elucidate the possible function(s) of myocilin, we further characterized a myocilin-α1-syntrophin complex in vivo.

Methods: : Interaction between myocilin and several components of DAPC was confirmed through co-immunoprecipitation experiments using mouse skeletal muscle and eye drainage structures. Muscle tissues from wildtype or transgenic mice expressing high levels of myocilin were analyzed by Western blotting and fluorescent immunohistochemistry. The expression of muscle atrophy markers in muscle tissues and several syntrophin isoforms in the eye angle tissues were quantified by real-time PCR.

Results: : Myocilin could be co-immunoprecipitated with components of DAPC including syntrophin, dystrobrevin, and dystrophin in mouse skeletal muscle. Expression of high levels of myocilin in skeletal muscles increased the localization of α1-syntrophin and its associated protein, neuronal nitric oxide synthase, to DAPC, suggesting that myocilin may be involved in the recruitment of α1-syntrophin to the complex. This recruitment may contribute to the stabilization of DAPC. Furthermore, the skeletal muscles of transgenic mice expressing high levels of myocilin were enlarged compared to wildtype mice. Phosphorylation of Akt and FoxO3, key regulators of muscle size, was increased, while the expression of muscle-specific RING finger protein-1 and atrogin-1, muscle atrophy markers, was decreased in the muscles of transgenic mice compared with wild-type mice. In the eye drainage structures, β-syntrophin, the major syntrophin isoform, was also co-precipitated with myocilin.

Conclusions: : Our results suggest that myocilin is a component of DAPC and plays a role as a regulator of muscle hypertrophy/atrophy pathways through the stabilization of DAPC. In the eye drainage structures, myocilin may be involved in the regulation of contractibility of ciliary muscle and in the modulation of the outflow pathway.

Keywords: proteins encoded by disease genes • trabecular meshwork 

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