(2013). Centriole distal appendages promote membrane docking, leading to cilia initiation. Genes dev,
The distal appendages (DAPs) of centrioles have been proposed to anchor cilia to the plasma membrane, but their molecular composition, assembly, and exact function in ciliogenesis remain poorly understood. Using quantitative centrosome proteomics and superresolution microscopy, we identified five DAP components, including one previously described (CEP164), one partially characterized (CEP89 [ccdc123]), and three novel (CEP83 [ccdc41], SCLT1, and FBF1) DAP proteins. Analyses of DAP assembly revealed a hierarchy. CEP83 recruits both SCLT1 and CEP89 to centrioles. Subsequent recruitment of FBF1 and CEP164 is independent of CEP89 but mediated by SCLT1. All five DAP components are essential for ciliogenesis; loss of CEP83 specifically blocks centriole-to-membrane docking. Undocked centrioles fail to recruit TTBK2 or release CP110, the two earliest modifications found on centrioles prior to cilia assembly, revealing centriole-to-membrane docking as a temporal and spatial cue promoting cilia initiation..
(2008). The epithelial polarity program: machineries involved and their hijacking by cancer. Oncogene,
The Epithelial Polarity Program (EPP) adapts and integrates three ancient cellular machineries to construct an epithelial cell. The polarized trafficking machinery adapts the cytoskeleton and ancestral secretory and endocytic machineries to the task of sorting and delivering different plasma membrane (PM) proteins to apical and basolateral surface domains. The domain-identity machinery builds a tight junctional fence (TJ) between apical and basolateral PM domains and adapts ancient polarity proteins and polarity lipids on the cytoplasmic side of the PM, which have evolved to perform a diversity of polarity tasks across cells and species, to provide 'identity' to each epithelial PM domain. The 3D organization machinery utilizes adhesion molecules as positional sensors of other epithelial cells and the basement membrane and small GTPases as integrators of positional information with the activities of the domain-identity and polarized trafficking machineries. Cancer is a disease mainly of epithelial cells (90% of human cancers are carcinomas that derive from epithelial cells) that hijacks the EPP machineries, resulting in loss of epithelial polarity, which often correlates in extent with the aggressiveness of the tumor. Here, we review how the EPP integrates its three machineries and the strategies used by cancer to hijack them..
(2007). Abi-1 forms an epidermal growth factor-inducible complex with Cbl: role in receptor endocytosis. Cell signaling,
The Abl-interactor (Abi) proteins are involved in the regulation of actin polymerization and have recently been shown to modulate epidermal growth factor receptor (EGFR) endocytosis. Here we describe the identification of a novel complex between Abi-1 and the Cbl ubiquitin ligase that is induced by stimulation with EGF. Notably, an Abi-1 mutant lacking the SH3 domain (DeltaSH3) fails to interact with Cbl and inhibits EGFR internalization. We show that expression of the Abi-1DeltaSH3 mutant inhibits Cbl accumulation at the plasma membrane after EGF treatment. We have previously shown that the oncogenic Abl tyrosine kinase inhibits EGFR internalization. Here we report that the oncogenic Abl kinase disrupts the EGF-inducible Abi-1/Cbl complex, highlighting the importance of Abl kinases and downstream effectors in the regulation of EGFR internalization. Thus, our work reveals a new role for oncogenic Abl tyrosine kinases in the regulation of the Abi-1/Cbl protein complex and uncovers a role for the Abi-1/Cbl complex in the regulation of EGFR endocytosis..
(2006). Abl tyrosine kinase regulates endocytosis of the epidermal growth factor receptor. J biol chem,
Signal attenuation from ligand-activated epidermal growth factor receptor (EGFR) is mediated in part by receptor endocytosis and trafficking to the lysosomal degradative compartment. Uncoupling the activated EGFR from endocytosis and degradation has emerged as a mechanism for oncogenic activation of the EGFR. The Abl nonreceptor tyrosine kinase is activated by ligand-stimulated EGFR, but the role of Abl in EGFR signaling has not been defined. Here we uncovered a novel role for the activated Abl kinase in the regulation of EGFR endocytosis. We show that activated Abl impairs EGFR internalization. Moreover, we show that activated Abl phosphorylates the EGFR primarily on tyrosine 1173, and that mutation of this site to phenylalanine restores ligand-dependent endocytosis of the EGFR in the presence of activated Abl. Furthermore, we show that activated Abl allows the ligand-activated EGFR to escape Cbl-dependent down-regulation by inhibiting the accumulation of Cbl at the plasma membrane in response to epidermal growth factor stimulation and disrupting the formation of the EGFR.Cbl complex without affecting Cbl protein stability. These findings reveal a novel role for Abl in promoting increased cell-surface expression of the EGFR and suggest that Abl/EGFR signaling may cooperate in human tumors..