Interestingly, even the residual subpopulation of perimeter APPL1 endosomes in starved cells were sensitive to Akt inhibition (Fig
Interestingly, even the residual subpopulation of perimeter APPL1 endosomes in starved cells were sensitive to Akt inhibition (Fig. migration. Thus, Dyn1- and Akt-dependent perimeter APPL1 endosomes function as a nexus that integrates signaling and receptor ABBV-4083 trafficking, which can be co-opted and amplified in mutant p53Cdriven malignancy cells to increase migration and invasion. Introduction Malignancy cell invasion and metastasis are mechanistically heterogeneous and adaptive processes contributing to the majority of cancer-related deaths (Bacac and Stamenkovic, 2008; Friedl and Alexander, 2011). While driver gene mutations and epigenetic alterations can increase malignancy cell proliferation, survival, invasion, and migration, they cannot account for all of the metastatic characteristics acquired through development of aggressive malignancy cells (Schmid, 2017). The underlying mechanisms governing the transition from main to aggressive tumors, during which malignancy cells acquire their adaptive metastatic abilities, are heterogeneous and remain largely unknown. Understanding the possible mechanisms leading to cancer metastasis is crucial for successful malignancy treatment. Signaling receptors, including receptor tyrosine kinases and integrins, control many aspects of cell physiology and behavior and are frequently dysregulated in and associated with the initiation and progression of malignancy (Sever and Brugge, 2015). Their signaling activities are, in turn, modulated by endocytic trafficking (Mellman and Yarden, 2013). Indeed, expression of gain-of-function (GOF) p53 mutants, which contribute to a more invasive phenotype in multiple cancers (Lang et al., 2004; Olive et al., 2004), results in increased recycling of EGF receptor (EGFR), cMET, and 1 integrins (Muller et al., 2009, 2013; Lanzetti and Di Fiore, 2017). This prospects to increased invasion and migration. The mechanisms responsible for GOF mutant p53Cdependent changes in endocytic trafficking remain incompletely comprehended. Endocytic trafficking of signaling receptors, which are internalized primarily via clathrin-mediated endocytosis (CME), entails delivery through unique early endosomal compartments marked by the scaffold proteins APPL1 (adaptor protein, phosphotyrosine interacting with PH domain name and leucine zipper 1) or EEA1 (early endosome antigen 1; Zoncu et al., 2009; Kalaidzidis et al., 2015). Receptors can be recycled back to the cell ABBV-4083 surface along either fast (i.e., directly from early endosomes) or slow (i.e., via perinuclear recycling endosomes) pathways. Alternatively, receptors can be packaged in intralumenal ABBV-4083 vesicles and delivered to lysosomes for degradation (Kalaidzidis et al., 2015). Troubles in quantitatively measuring fast recycling render this the least mechanistically comprehended of these trafficking pathways. GOF p53-dependent increases in receptor recycling require the Rab11 effector, Rab-coupling protein (RCP; Muller et al., 2009, 2013). However, RCP expression levels are not regulated by p53; thus the mechanisms by which mutant p53 regulates components of the endocytic machinery to alter endocytic trafficking remain unknown. Also unknown are the identities of the endosomal compartments from which ABBV-4083 this recycling occurs, IL-11 although Rab11 is usually associated with recycling endosomes and the slow recycling pathway (Wandinger-Ness and Zerial, 2014). The temporal and functional relationships between the early APPL1 and EEA1 endosomes also remain incompletely defined (Zoncu et al., 2009; Kalaidzidis et al., 2015). One study suggested that APPL1 endosomes are intermediates along a maturation pathway from nascent endocytic vesicles to EEA1-positive early endosomes (Zoncu et al., 2009), while a second study suggested that they function as distinct, albeit dynamically interacting, sorting stations (Kalaidzidis et al., 2015). ABBV-4083 APPL1-positive endosomes are often referred to as signaling endosomes because APPL1, through its scaffolding properties, regulates many signaling events including Akt/GSK3 activity (Schenck et al., 2008; Ding et al., 2016; Diggins and Webb, 2017). In addition, APPL1 endosomes have been linked to the regulation of cell migration (Tan et al., 2010; Broussard et al., 2012; Ding et al., 2016) and to recycling of some G proteinCcoupled receptors (GPCRs; Jean-Alphonse et al., 2014; Sposini et al., 2017). APPL1 endosomes have been reported to be regulated by PKA signaling downstream of.