Senescence and PD-linked gene mutations have reciprocal pathological interactions where (i) senescence causes PD-relevant neuropathology; (ii) PD-linked mutant genes (alpha-synuclein, LRRK2, Vps35) cause premature senescence; and (iii) senescence participates in neuropathology caused by PD-linked genes. First, we will use novel mouse models of premature senescence to test whether premature senescence in specific cell types causes PD-like neuropathology. Second, we will combine mouse models of senescence and familial PD to test whether senescence participates in neuropathology caused by mutant PD-linked genes. Specifically, we will determine if pathology in a PD mouse model causes premature senescence and whether removing senescent cells from brain can prevent PD pathology. Finally, we will perform gene expression analysis of PD brains and mouse brains, at a single-cell level, to gain high-resolution insights about cellular processes that link aging and PD pathology.