%0 Generic %A Zhang, Jinzhong %A He, Jing %A Johnson, Jennifer L. %A Napolitano, Gennaro %A Ramadass, Mahalakshmi %A Rahman, Farhana %A Catz, Sergio D. %D 2019 %T Cross-regulation of defective endolysosome trafficking and enhanced autophagy through TFEB in UNC13D deficiency %U https://tandf.figshare.com/articles/dataset/Cross-regulation_of_defective_endolysosome_trafficking_and_enhanced_autophagy_through_TFEB_in_UNC13D_deficiency/7959500 %R 10.6084/m9.figshare.7959500.v2 %2 https://tandf.figshare.com/ndownloader/files/14814755 %2 https://tandf.figshare.com/ndownloader/files/14814758 %2 https://tandf.figshare.com/ndownloader/files/14814761 %2 https://tandf.figshare.com/ndownloader/files/14814764 %2 https://tandf.figshare.com/ndownloader/files/14814767 %2 https://tandf.figshare.com/ndownloader/files/14814770 %2 https://tandf.figshare.com/ndownloader/files/14814773 %2 https://tandf.figshare.com/ndownloader/files/14814776 %2 https://tandf.figshare.com/ndownloader/files/14814779 %2 https://tandf.figshare.com/ndownloader/files/14814782 %K Autophagy %K endosomal trafficking %K FHL3 %K fusion %K lysosomal signaling %K secretion %K TFEB %X

Several lines of evidence support the occurrence of cross-regulation between the endocytic pathway and autophagy, but the molecular mechanisms regulating this process are not well-understood. Here, we show that the calcium sensor UNC13D regulates the molecular mechanism of late endosomal trafficking and endosomal maturation, and defects in UNC13D lead to macroautophagy upregulation. unc13d-null cells showed impaired endosomal trafficking and defective endocytic flux. The defective phenotypes were rescued by the expression of UNC13D but not by its STX7-binding-deficient mutant. This defective endosomal function in UNC13D-deficient cells resulted in increased autophagic flux, increased long-lived protein degradation, decreased SQSTM1/p62 protein levels and increased autolysosome formation as determined by biochemical, microscopy and structural methods. The autophagic phenotype was not associated with increased recruitment of the UNC13D-binding proteins and autophagy regulators, RAB11 or VAMP8, but was caused, at least in part, by TFEB-mediated upregulation of a subset of autophagic and lysosomal genes, including Atg9b. Downregulation of TFEB decreased Atg9b levels and decreased macroautophagy in unc13d-null cells. UNC13D upregulation corrected the defects in endolysosomal trafficking and decreased the number of accumulated autophagosomes in a cellular model of the lysosomal-storage disorder cystinosis, under both fed and starvation conditions, identifying UNC13D as an important new regulatory molecule of autophagy regulation in cells with lysosomal disorders.

ACTB: actin, beta; CTSB: cathepsin B; EEA1: early endosome antigen 1; ESCRT: endosomal sorting complex required for transport; FHL3: familial hemophagocytic; lymphohistiocytosis type 3; HEX: hexosaminidase; HLH: hemophagocytic lymphohistiocytosis; LSD: lysosomal storage disorder; MEF: mouse embryonic fibroblast; SEM: standard errors of the mean; SNARE: soluble n-ethylmaleimide-sensitive-factor attachment receptor; STX: syntaxin; SYT7: synaptotagmin VII; TFE3: transcription factor E3; TFEB: transcription factor EB; TIRF: total internal reflection fluorescence ULK1: unc-51 like kinase 1; UNC13D: unc-13 homolog d; VAMP: vesicle-associate membrane protein; WT: wild-type

%I Taylor & Francis