title: Selective activation of p120ctn-Kaiso signaling to unlock contact inhibition of ARPE-19 cells without epithelial-mesenchymal transition.
abstract: Contact-inhibition ubiquitously exists in non-transformed cells and explains the poor regenerative capacity of in vivo human retinal pigment epithelial cells (RPE) during aging, injury and diseases. RPE injury or degeneration may unlock mitotic block mediated by contact inhibition but may also promote epithelial-mesenchymal transition (EMT) contributing to retinal blindness. Herein, we confirmed that EMT ensued in post-confluent ARPE-19 cells when contact inhibition was disrupted with EGTA followed by addition of EGF and FGF-2 because of activation of canonical Wnt and Smad/ZEB signaling. In contrast, knockdown of p120-catenin (p120) unlocked such mitotic block by activating p120/Kaiso, but not activating canonical Wnt and Smad/ZEB signaling, thus avoiding EMT. Nuclear BrdU labeling was correlated with nuclear release of Kaiso through p120 nuclear translocation, which was associated with activation of RhoA-ROCK signaling, destabilization of microtubules. Prolonged p120 siRNA knockdown followed by withdrawal further expanded RPE into more compact monolayers with a normal phenotype and a higher density. This new strategy based on selective activation of p120/Kaiso but not Wnt/β-catenin signaling obviates the need of using single cells and the risk of EMT, and may be deployed to engineer surgical grafts containing RPE and other tissues.
authors.affiliation: Tissue Tech, Inc, Ocular Surface Center, and Ocular Surface Research & Education Foundation, Miami, Florida, United States of America.
authors.forename: Hung-Chi
authors.initials: HC
authors.lastname: Chen
authors.forename: Ying-Ting
authors.initials: YT
authors.lastname: Zhu
authors.forename: Szu-Yu
authors.initials: SY
authors.lastname: Chen
authors.forename: Scheffer C G
authors.initials: SC
authors.lastname: Tseng
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D051177:Catenins / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D003260:Contact Inhibition / Q000187:drug effects / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000378:metabolism / Q000494:pharmacology; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000502:physiology*; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*; D000095002:Delta Catenin
chemical_list: D051177:Catenins; D014157:Transcription Factors; C492254:ZBTB33 protein, human; D016222:Fibroblast Growth Factor 2; D004815:Epidermal Growth Factor; D000095002:Delta Catenin; C000722347:CTNND1 protein, human