title: Rab7 Regulates CDH1 Endocytosis, Circular Dorsal Ruffles Genesis, and Thyroglobulin Internalization in a Thyroid Cell Line.
abstract: Rab7 regulates the biogenesis of late endosomes, lysosomes, and autophagosomes. It has been proposed that a functional and physical interaction exists between Rab7 and Rac1 GTPases in CDH1 endocytosis and ruffled border formation. In FRT cells over-expressing Rab7, increased expression and activity of Rac1 was observed, whereas a reduction of Rab7 expression by RNAi resulted in reduced Rac1 activity, as measured by PAK1 phosphorylation. We found that CDH1 endocytosis was extremely reduced only in Rab7 over-expressing cells but was unchanged in Rab7 silenced cells. In Rab7 under or over-expressing cells, Rab7 and LC3B-II co-localized and co-localization in large circular structures occurred only in Rab7 over-expressing cells. These large circular structures occurred in about 10% of the cell population; some of them (61%) showed co-localization of Rab7 with cortactin and f-actin and were identified as circular dorsal ruffles (CDRs), the others as mature autophagosomes. We propose that the over-expression of Rab7 is sufficient to induce CDRs. Furthermore, in FRT cells, we found that the expression of the insoluble/active form of Rab7, rather than Rab5, or Rab8, was inducible by cAMP and that cAMP-stimulated FRT cells showed increased PAK1 phosphorylation and were no longer able to endocytose CDH1. Finally, we demonstrated that Rab7 over-expressing cells are able to endocytose exogenous thyroglobulin via pinocytosis/CDRs more efficiently than control cells. We propose that the major thyroglobulin endocytosis described in thyroid autonomous adenomas due to Rab7 increased expression, occurs via CDRs. J. Cell. Physiol. 231: 1695-1708, 2016. © 2015 Wiley Periodicals, Inc.
authors.affiliation: IEOS Istituto di Endocrinologia e Oncologia Sperimentale "G. Salvatore", National Council of Research, Napoli, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Mascia
authors.affiliation: IEOS Istituto di Endocrinologia e Oncologia Sperimentale "G. Salvatore", National Council of Research, Napoli, Italy.
authors.forename: Flaviana
authors.initials: F
authors.lastname: Gentile
authors.affiliation: Department of Molecular Medicine and Medical Biotechnologies, University "Federico II", Napoli, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Izzo
authors.affiliation: Department of Molecular Medicine and Medical Biotechnologies, University "Federico II", Napoli, Italy.
authors.forename: Nunzia
authors.initials: N
authors.lastname: Mollo
authors.affiliation: Department of Biological and Environmental Sciences and Technologies, University of Salento (DiSTeBA), Lecce, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: De Luca
authors.affiliation: Department of Biological and Environmental Sciences and Technologies, University of Salento (DiSTeBA), Lecce, Italy.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Bucci
authors.affiliation: Department of Molecular Medicine and Medical Biotechnologies, University "Federico II", Napoli, Italy.
authors.forename: Lucio
authors.initials: L
authors.lastname: Nitsch
authors.affiliation: IEOS Istituto di Endocrinologia e Oncologia Sperimentale "G. Salvatore", National Council of Research, Napoli, Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Calì
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001343:Autophagy; D015820:Cadherins / Q000378:metabolism*; D002460:Cell Line; D022081:Cell Surface Extensions / Q000187:drug effects / Q000201:enzymology*; D051356:Cortactin / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010766:Phosphorylation; D010873:Pinocytosis; D034622:RNA Interference; D011916:Rats, Inbred F344; D015290:Second Messenger Systems; D013954:Thyroglobulin / Q000378:metabolism*; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D013997:Time Factors; D014162:Transfection; D014617:Vacuoles / Q000187:drug effects / Q000201:enzymology*; D054462:p21-Activated Kinases / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000090802:rab7 GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000199:Actins; D015820:Cadherins; D051356:Cortactin; D000242:Cyclic AMP; D008869:Microtubule-Associated Proteins; D013954:Thyroglobulin; D054462:p21-Activated Kinases; D020691:rab GTP-Binding Proteins; D000090802:rab7 GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; C000610228:CDH1 protein, rat; C526109:Anxa3 protein, rat; C000716466:rab7 GTP-binding proteins, rat; C515906:Pak1 protein, rat; C499134:Rac1 protein, rat