In this proposal, utilizing infection of cultured human muscle with BetaAPP or PrPC genes in adenovirus vector, we will pursue the following aims:
Aim 1. Determine whether long-term overexpression of BetaAPP or PrPc genes in normal human muscle cultured i) aneurally and ii) innervated, using adenovirus vector, will induce the IBM-phenotype, including a) vacuolization and the other aspects of IBM muscle degeneration b) PHFs, c) congophilic amyloid deposits and d) accumulation of the other IBM- characteristic proteins.
Aim 2. Determine whether increased ApoE in the muscle fiber (either by genetic overexpression through an adenovirus vector or by increased exposure from the culture medium) will facilitate development of the IBM phenotype in cultured normal human muscle concurrent with Beta APP and/or PrPc gene overexpression.
Aim 3 A. Determine whether challenging cultured h-IBM muscle aneurally or innervated with extra copies of the BetaAPP or PrPc gene will accelerate coordinated development in them of the IBM-phenotype and aggravate its severity, as compared to a) cultured uninfected h-IBM muscle and b) normal cultured human muscle with concurrently overexpressed BetaAPP and PrPc. (This is necessary because cultured uninfected h-IBM muscle fibers express some aspects of the IBM phenotype including increased accumulation of BetaAPP and PrPc, but this is present only in 20-40% of the muscle fibers at any given time -the severely affected fibers are dying while others do not yet express the phenotype).
Aim 3 B. Determine whether accumulation of ApoE (either by genetic expression thru an adenovirus vector or by exposure from the culture medium) will facilitate development of the IBM phenotype in cultured h-IBM muscle fibers without and with overexpressed BetaAPP or PrPc in them.
Aim 3 C. Determine whether infection of cultured h-IBM with adenovirus carrying BetaAPP or PrPc cDNA in antisense orientation will inhibit manifestation of the IBM phenotype. The broad objectives of our research are to better understand a) molecular mechanisms leading to increased accumulation in h- and s-IBM of a group of proteins that are normally not expressed extrajunctionally in adult human muscle, and b) their role in the disease process. Our long-term coals are to learn the molecular pathogenic mechanisms leading to h- and s-IBM which could eventually lead to treatment.
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