Organellophagy is the selective degradation of organelles by autophagosomes. Alterations in organellophagy are associated with several disorders including neurodegeneration, heart disease, obesity, and cancer. Selectivity in organellophagy is achieved by the specific binding autophagosome protein ATG8 to proteins on the target compartment. A distinct set of proteins is then used by selective autophagy pathways to expand the autophagosome around the specific target. Nucleophagy, the selective degradation of the nucleus by autophagosomes, is up regulated in laminopathies and in response to oncogenic stress. But whether nucleophagy utilizes proteins that are required for selective autophagy patways remains unclear. Our primary goal is to understand the molecular mechanisms underlying how the nucleus is specifically degraded by autophagosomes. In order to uncover these mechanisms we plan to exploit nuclear degradation during mating in Tetrahymena thermophila. Tetrahymena selective degrade their entire (macronucleus) nucleus in an autophagy dependent manner, as part of normal mating. Importantly this process can be induced in the lab and occurs in predictable and identifiable stages making nucleophagy in Tetrahymena straightforward to monitor. Preliminary work in our lab has shown that nucleophagy in Tetrahymena, may employ selective autophagy proteins. Specifically, we identified a Tetrahymena homolog of SNX4 (TtSNX4), a protein that is required for the selective degradation of mitochondria by autophagosomes (mitophagy) in yeast as candidate for regulating nucleophagy in Tetrahymena. We find that TtSNX4 localizes specifically to the degrading nucleus in a phosphoiositide 3 kinase (PI3K) dependent manner and deletion of TtSNX4 results in impaired nuclear condensation, an early stage in the degradation process that is dependent on nucleases provided by mitochondria that have been engulfed by autophagosomes. Importantly, proteins like SNX4, that possess PX-BAR domains have been shown to bind PI(3)P, a peoduct of PI3K. Therefore we hypothesize that TtSNX4 may regulate the delivery of mitochondrial nucleases to the nucleus in a PI(3)P dependent manner.