MT5-MMP C-terminal mutations reduce C99 and β accumulation: A foundation for peptide-based Alzheimer's interventions

Our prior work established a pivotal role for membrane-type 5-matrix metalloproteinase (MT5-MMP) in Alzheimers disease (AD) pathogenesis, particularly through its C-terminal transmembrane (TM) and intracellular (IC) domains, which influence the fate of major toxic metabolites of toxic amyloid precursor protein (APP) metabolites, particularly C99 and A{beta}. Hypothesizing that modifications in these domains could modulate C99 and A{beta} levels, we engineered MT5-MMP variants with deletions or substitutions in the TM/IC domains or specific IC amino acid clusters. When co-transfected into human cell lines accumulating C99, certain IC domain mutations promoted C99 degradation and reduced A{beta} levels, while other mutations had divergent effects. High content imaging further revealed that MT5-MMP IC domain modification altered C99 subcellular trafficking within the endomembrane system, impacting its processing. Proximity ligation assays confirmed the importance of the IC domain in MT5-MMP colocalization and potential interaction with C99. To translate these findings, we synthetized peptides mimicking the MT5-MMP IC domain, incorporating mutations that reduce C99 and/or A{beta} levels. One peptide effectively lowered C99 levels in an in vitro AD model. Overall, this study highlights the importance of specific amino acids in the C-terminal domains of MT5-MMP for regulating C99 and A{beta} metabolism. It also provides new insights for developing MT5-MMP-based therapeutic strategies against AD, exploiting the unique properties of specific mutations in MT5-MMP to prevent toxic accumulation of C99 and A{beta}. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=86 SRC="FIGDIR/small/655451v3_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@a6b04aorg.highwire.dtl.DTLVardef@1800721org.highwire.dtl.DTLVardef@542505org.highwire.dtl.DTLVardef@4a6d7b_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGRAPHICAL ABSTRACTC_FLOATNO C_FIG