title: E50K-OPTN-induced retinal cell death involves the Rab GTPase-activating protein, TBC1D17 mediated block in autophagy.
abstract: The protein optineurin coded by OPTN gene is involved in several functions including regulation of endocytic trafficking, autophagy and signal transduction. Certain missense mutations in the gene OPTN cause normal tension glaucoma. A glaucoma-causing mutant of optineurin, E50K, induces death selectively in retinal cells. This mutant induces defective endocytic recycling of transferrin receptor by causing inactivation of Rab8 mediated by the GTPase-activating protein, TBC1D17. Here, we have explored the mechanism of E50K-induced cell death. E50K-OPTN-induced cell death was inhibited by co-expression of a catalytically inactive mutant of TBC1D17 and also by shRNA mediated knockdown of TBC1D17. Endogenous TBC1D17 colocalized with E50K-OPTN in vesicular structures. Co-expression of transferrin receptor partially protected against E50K-induced cell death. Overexpression of the E50K-OPTN but not WT-OPTN inhibited autophagy flux. Treatment of cells with rapamycin, an inducer of autophagy, reduced E50K-OPTN-induced cell death. An LC3-binding-defective mutant of E50K-OPTN showed reduced cell death, further suggesting the involvement of autophagy. TBC1D17 localized to autophagosomes and inhibited autophagy flux dependent on its catalytic activity. Knockdown of TBC1D17 rescued cells from E50K-mediated inhibition of autophagy flux. Overall, our results suggest that E50K mutant induced death of retinal cells involves impaired autophagy as well as impaired transferrin receptor function. TBC1D17, a GTPase-activating protein for Rab GTPases, plays a crucial role in E50K-induced impaired autophagy and cell death.
authors.affiliation: Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India.
authors.forename: Madhavi Latha Somaraju
authors.initials: ML
authors.lastname: Chalasani
authors.affiliation: Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India.
authors.forename: Asha
authors.initials: A
authors.lastname: Kumari
authors.affiliation: Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India.
authors.forename: Vegesna
authors.initials: V
authors.lastname: Radha
authors.affiliation: Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India.
authors.forename: Ghanshyam
authors.initials: G
authors.lastname: Swarup
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D019084:Fluorescent Antibody Technique, Indirect; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D005822:Genetic Vectors; D051379:Mice; D018613:Microscopy, Confocal; D020691:rab GTP-Binding Proteins
chemical_list: D005136:Eye Proteins; D020690:GTPase-Activating Proteins; C581544:TBC1D17 protein, human; C082377:RAB8A protein, human; D020691:rab GTP-Binding Proteins
references.citation: J Cell Sci. 2012 Nov 1;125(Pt 21):5026-39
references.pmid: 22854040
references.citation: FEBS Lett. 2008 Mar 19;582(6):997-1002
references.pmid: 18307994
references.citation: Mol Vis. 2007 Feb 02;13:151-63
references.pmid: 17293779
references.citation: Cell Mol Life Sci. 2011 Oct;68(20):3349-58
references.pmid: 21687989
references.citation: Exp Eye Res. 2010 Aug;91(2):273-85
references.pmid: 20650699
references.citation: Curr Biol. 2007 Aug 21;17(16):1438-43
references.pmid: 17702576
references.citation: J Biol Chem. 2003 Dec 26;278(52):52188-94
references.pmid: 14551197
references.citation: Science. 2002 Feb 8;295(5557):1077-9
references.pmid: 11834836
references.citation: Curr Opin Pharmacol. 2013 Feb;13(1):5-11
references.pmid: 23041078
references.citation: J Biosci. 2004 Jun;29(2):129-31
references.pmid: 15295207
references.citation: Br J Ophthalmol. 2011 Jan;95(1):131-41
references.pmid: 20956277
references.citation: Cell Cycle. 2012 Aug 1;11(15):2808-18
references.pmid: 22801549
references.citation: Annu Rev Genet. 2009;43:67-93
references.pmid: 19653858
references.citation: Invest Ophthalmol Vis Sci. 2013 Aug 23;54(8):5712-9
references.pmid: 23975727
references.citation: Invest Ophthalmol Vis Sci. 2003 Aug;44(8):3675-84
references.pmid: 12882823
references.citation: Hum Mol Genet. 2013 Sep 1;22(17):3559-67
references.pmid: 23669351
references.citation: Tohoku J Exp Med. 2010 May;221(1):1-10
references.pmid: 20431268
references.citation: J Biol Chem. 2011 Feb 4;286(5):3618-29
references.pmid: 21059646
references.citation: Autophagy. 2013 Apr;9(4):510-27
references.pmid: 23357852
references.citation: Mol Cell. 2012 Feb 24;45(4):553-66
references.pmid: 22365832
references.citation: PLoS One. 2011 Mar 07;6(3):e17477
references.pmid: 21408173
references.citation: Invest Ophthalmol Vis Sci. 2004 Dec;45(12):4359-67
references.pmid: 15557444
references.citation: Eye (Lond). 2011 May;25(5):587-95
references.pmid: 21562585
references.citation: Invest Ophthalmol Vis Sci. 2004 Sep;45(9):3122-30
references.pmid: 15326130
references.citation: Invest Ophthalmol Vis Sci. 2003 Sep;44(9):3880-4
references.pmid: 12939304
references.citation: Int Rev Cell Mol Biol. 2012;294:223-58
references.pmid: 22364875
references.citation: Exp Mol Med. 2012 Feb 29;44(2):89-98
references.pmid: 22257884
references.citation: Science. 2011 Jul 8;333(6039):228-33
references.pmid: 21617041
references.citation: PLoS Pathog. 2010 Feb 19;6(2):e1000778
references.pmid: 20174559
references.citation: Cell. 2010 Feb 5;140(3):313-26
references.pmid: 20144757
references.citation: J Glaucoma. 2004 Aug;13(4):299-303
references.pmid: 15226658
references.citation: Invest Ophthalmol Vis Sci. 2007 Apr;48(4):1607-14
references.pmid: 17389490
references.citation: J Biol Chem. 2007 Aug 17;282(33):24131-45
references.pmid: 17580304
references.citation: Ophthalmic Res. 2009;42(4):176-84
references.pmid: 19672125
references.citation: Mol Vis. 2006 Oct 26;12:1272-82
references.pmid: 17110910
references.citation: Biochim Biophys Acta. 2013 Mar;1833(3):503-10
references.pmid: 23220125
references.citation: J Cell Biol. 2005 Nov 21;171(4):603-14
references.pmid: 16286508
references.citation: Br J Ophthalmol. 2006 Mar;90(3):262-7
references.pmid: 16488940
references.citation: J Cell Biol. 2007 Jun 18;177(6):1133-43
references.pmid: 17562788
references.citation: Neuropathology. 2011 Dec;31(6):569-74
references.pmid: 21284751
references.citation: Proc Natl Acad Sci U S A. 2002 Apr 30;99(9):6047-52
references.pmid: 11972060
references.citation: Mol Vis. 2009 Aug 20;15:1649-54
references.pmid: 19710941
references.citation: Arch Ophthalmol. 2000 Feb;118(2):235-45
references.pmid: 10676789
references.citation: Hum Mol Genet. 2010 Jul 1;19(13):2606-15
references.pmid: 20388642
references.citation: BMC Cell Biol. 2010 Jan 19;11:4
references.pmid: 20085643
references.citation: Lancet. 2004 May 22;363(9422):1711-20
references.pmid: 15158634
references.citation: Nature. 2010 May 13;465(7295):223-6
references.pmid: 20428114
references.citation: Invest Ophthalmol Vis Sci. 2009 Sep;50(9):4267-72
references.pmid: 19443730
references.citation: PLoS One. 2009;4(4):e5114
references.pmid: 19340308
references.citation: J Cell Sci. 2006 May 1;119(Pt 9):1703-14
references.pmid: 16595549
references.citation: PLoS Pathog. 2009 Jul;5(7):e1000521
references.pmid: 19609363
references.citation: PLoS One. 2010 Jul 12;5(7):e11547
references.pmid: 20634958