FKBP38 participates in the regulation of the autophagic pathway

WAPPNER, P; COLOMBO MI; MELANI, M; AGUILERA MO

Merlo, San Luis

Congreso; XXXV Reunión Anual de la Sociedad de Biología de Cuyo.; 2017

Sociedad Sociedad de Biología de Cuyo

Autophagy is a process in which a double membrane vesicle sequesters cytoplasmic material destined to degradation. FKBP38 is a member of the family of FK506 binding proteins which play a role in some critical cellular functions such trafficking and folding of proteins. Recently has been showed that FKBP38 participates in mitophagy, a specific kind of autophagy, but not data are present about the participation in the general pathway. First, we analyzed LC3 processing (the most used marker of autophagy) by western blot and the LC3 positive vesicles number by confocal microscopy. The single overexpression of FKBP38 in HeLa cells stimulates the pathway while the knock down of the protein using siRNA leads to inhibition of starvation induced autophagy. When we examined in HeLa cells overexpressing FKBP38 the size and morphology of mitochondria by fluorescence microscopy and functionality by flow cytometry using TMRE staining we do not observed mitochondrial damage. These results rule out mitophagy activation. Afterwards, using confocal microscopy plus deconvolution we observed that FKBP38 colocalizes with Beclin1 and Atg14L, members of the PI3K complex. Using FRET assays we observed that FKBP38 interact with Beclin1, and this interaction strongly diminished when we deleted the transmembrane domain of FKBP38. Furthermore, FKBP38 regulates the formation of PI3P by PI3K. This is evidenced by change in the number of vesicles positives to DFCP1, a specific PI3P binder in autophagy, depending on the expression levels of FKBP38. Taken together, our data indicate that FKBP38 regulates the autophagy modulating early stages of the pathway