Centrosomal P4.1-associated protein (CPAP) positively regulates endocytic vesicular transport and lysosome targeting of EGFR

Abstract

Centrosomal P4.1-associated protein (CPAP) plays a critical role in restricting the centriole length in human cells. Here, we report a novel positive regulatory role for CPAP in endosome maturation during internalized-cell surface receptor trafficking. We found that CPAP is required for targeting ligand-bound cell surface receptor to the lysosome for degradation. While routing of ligand-engaged receptor, which is targeted for degradation or recycling, into early endosomes is not impacted by CPAP-deficiency, sequential transfer of the receptor to late endosome is severely diminished in CPAP-depleted cells. Importantly, activation and recruitment of Rab7, but not Rab5, is compromised upon CPAP depletion indicating its positive regulatory role in early to late endosome transition. Overall, this regulatory role of CPAP in endosome maturation provides new insights in understanding the cellular functions of CPAP, which is well recognized to be critical for centriole duplication and ciliogenesis.