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Title: Proteomic and genetic analyses demonstrate a critical role for the complement system in basal deposit formation in a mouse model of inherited macular dystrophy

Author
item GARLAND, DONITA - Harvard Medical School
item GODIN, ROSARIE - Harvard Medical School
item SPEICHER, KAYE - Wistar Institute
item Harnly, James - Jim
item LAMBRIS, JOHN - University Of Pennsylvania
item ERIC, ERIC - Harvard Medical School

Submitted to: Human Molecular Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2013
Publication Date: 8/13/2013
Citation: Garland, Donita, Godin, R.F., Speicher, K., Harnly, J.M., Lambris, J.D., Eric, E.A. 2013. Proteomic and genetic analyses demonstrate a critical role for the complement system in basal deposit formation in a mouse model of inherited macular dystrophy. Human Molecular Genetics. 23:52-68 (2014).

Interpretive Summary: Macular degeneration is accompanied by drusen formation in the retina. The immune system, complement proteins and inflammation have been implicated in drusen formation but the underlying mechanisms are not understood. Drusen formation is proceeded by basal deposits in the Bruch's membrane. A mouse model with was used with induced genetic mutation that provided similar basal deposits. Proteomics was used to study the mechanisms involved in the formation of basal deposits and double mutant mice were used to elucidate the role of the complement system proteins. The results demonstrated a critical role for an intact complement system in early stages of drusen formation and implicated the complement system in the pathogenesis of macular degeneration.

Technical Abstract: Macular degenerations, inherited and age-related, are important causes of vision loss. A common feature of both is drusen formation which contributes to vision loss. The immune system, complement proteins and inflammation have been implicated in drusen formation but the underlying mechanisms are not understood. To investigate early events in drusen formation, we used an animal model of the inherited macular degenerations, Doyne Honeycomb Retinal Dystrophy and Malattia Leventinese (DHRD/ML) which are both caused by an R345W mutation in the EFEMP1 gene. Gene targeted Efemp1-R345W mice develop extensive basal laminar deposits which are considered precursors to drusen. Proteomic and mouse genetic approaches were used to study the mechanisms involved in the formation of basal deposits in the Efemp1-R345W mice. Proteomics defined the composition of Bruch’s membrane, the “aging” of Bruch’s membrane/choroid, and protein changes induced by the mutation, demonstrated the late onset aspect of the mutation induced disorder and identified significant changes in proteins with immune-related function. Complement C3 and C4 were both increased in mutant mice. To determine the role of the complement sytem in basal deposit formation in these mice, we generated double mutant Efemp1-R345W:C3 null mice. Inactivation of C3 in the Efemp1-R345W mice prevented basal laminar deposit formation. The results demonstrated a critical role for an intact complement system in early stages of drusen formation and implicated the complement system in the pathogenesis of DHRD/ML.