KCTD15 INDUCES GIANT VACUOLES FORMATION IN MAMMALIAN CELLS.

ZARELLI VEP, LOPEZ DE ARMENTIA MM AND COLOMBO MI.

Sorrento

Congreso; The 2018 Golgi meeting: Membrane trafficking in cell organization and homeostasis.; 2018

FEBS

Kctd15 belongs to the potassium channel tetramerization domain (KCTD) proteins that contain bric-a-brac, tramtrak and broad complex (BTB) domain. The BTB domain is a protein-protein interaction motif that is found throughout eukaryotes. Kctd15 homologs are found in different vertebrates, representing a well-conserved family. It has been demonstrated that Kctd15 affects Wnt signaling and AP-2 transcription factor function during embryonic development in zebrafish. The precise molecular mechanism of these processes remains unknown. To better understand the role of Kctd15 we transfected CHO, MEF and HeLa cells with Kct15-FOS plasmid and analyzed the protein localization by immunofluorescence using a confocal microscope. We observed the formation of giant vacuoles when we overexpressed Kctd15 in mammalian cells. In order to characterize these structures, we used endosomal markers, such as Rab5, Rab7, CD63 and lysosomal markers (Lysotraker). Our recent results indicate that these vacuoles do not acquire Rab5, Rab7 neither CD63. In addition, Lysotraker was not observed inside the vacuoles. Taken together, these results suggest that the vacuoles induced by Kctd15 do not correspond to early/late endosomal compartments. Indeed, we used other Rab proteins to characterized these vacuoles and we did observe Rab29 at the membrane of these structures, suggesting an interaction with the trans-Golgi. We consider that the particular phenomenon induced by Kctd15 overexpression might be part of the regulation of some of the pathways it modulates.