title: Regulation of podocalyxin trafficking by Rab small GTPases in epithelial cells.
abstract: The characteristic feature of polarity establishment in MDCK II cells is transcytosis of apical glycoprotein podocalyxin (PCX) from the outer plasma membrane to the newly formed apical domain. This transcytotic event consists of multiple steps, including internalization from the plasma membrane, transport through early endosomes and Rab11-positive recycling endosomes, and delivery to the apical membrane. These steps are known to be tightly coordinated by Rab small GTPases, which act as molecular switches cycling between active GTP-bound and inactive GDP-bound states. However, our knowledge regarding which sets of Rabs regulate particular steps of PCX trafficking was rather limited. Recently, we have performed a comprehensive analysis of Rab GTPase engagement in the transcytotic pathway of PCX during polarity establishment in 2-dimensional (2D) and 3-dimensional (3D) MDCK II cell cultures. In this Commentary we summarize our findings and set them in the context of previous reports.
authors.affiliation: a Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences , Graduate School of Life Sciences, Tohoku University , Sendai, Miyagi , Japan.
authors.forename: Paulina S
authors.initials: PS
authors.lastname: Mrozowska
authors.affiliation: a Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences , Graduate School of Life Sciences, Tohoku University , Sendai, Miyagi , Japan.
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D016764:Cell Polarity; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology*; D061985:Madin Darby Canine Kidney Cells; D021381:Protein Transport; D012795:Sialoglycoproteins / Q000378:metabolism*; D057900:Transcytosis; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D012795:Sialoglycoproteins; C001643:podocalyxin; D020691:rab GTP-Binding Proteins
keywords: MDCK cells; Rab small GTPases; epithelial cell polarity; podocalyxin/gp135; recycling endosome; transcytosis