A novel protein involved in Golgi homeostasis.

ZARELLI, VE; COLOMBO, MI; ZARELLI VEP, LOPEZ DE ARMENTIA MM AND COLOMBO MI.; ORTEGA, M

Salta

Congreso; LV Annual SAIB Meeting and XIV PABMB Congress; 2019

Kctd15 belongs to the potassium channel tetramerization domain (KCTD) proteinsthat contain bric-a-brac, tramtrak and broad complex (BTB) domain. The BTBdomain is a protein-protein interaction motif that is found throughout eukaryotes.Kctd15 homologs are found in different vertebrates, representing a well-conservedfamily. It has been demonstrated that Kctd15 affect Wnt signaling and AP-2transcription factor function during embryonic development in zebrafish. The precisemolecular mechanism of these processes remains unknown. To better understandthe role of Kctd15 we transfected CHO, MEF and HeLa cells with Kct15-FOSplasmid and analyzed the protein localization by immunofluorescence using aconfocal microscope. We observed the formation of giant vacuoles when Kctd15 activity is increased in mammalian cells. These structures do not acquired Rab5, Rab7 neither CD63. In addition, Lysotraker was not observed inside the vacuoles. Taken together, these results suggest that the vacuoles induced by Kctd15 are not endosomal compartments. Following characterization, we where able to trace the origin of these vacuoles to Golgi complex. Kctd15 overexpression mimics Brefeldin A effects in disrupting the cis-Golgi cisternae. Indeed, we used other Rab proteins to characterizedthese vacuoles and did observe Rab29, Rab34 and Rab38 in the membrane of these structures. Furthermore, Kctd15 colocalization with TGN38/46 suggesting a link with a most posterior Golgi region. We consider that the particular phenomenon induced by Kctd15 overexpression might be part of the regulation of some of the pathways it modulates by affecting cell homeostasis.