Mutation in the βA3/A1-crystallin gene impairs phagosome degradation in the retinal pigmented epithelium of the rat.
Phagocytosis of the shed outer segment discs of photoreceptors is a major function of the retinal pigmented epithelium (RPE). We demonstrate for the first time that βA3/A1-crystallin, a major structural protein of the ocular lens, is expressed in RPE cells. Further, by utilizing the Nuc1 rat, in which the βA3/A1-crystallin gene is mutated, we show that this protein is required by RPE cells for proper degradation of outer segment discs that have been internalized in phagosomes. We also demonstrate that in wild-type RPE, βA3/A1-crystallin is localized to the lysosomes. However, in the Nuc1 RPE, βA3/A1-crystallin fails to translocate to the lysosomes, perhaps because misfolding of the mutant protein masks sorting signals required for proper trafficking. The digestion of phagocytized outer segments requires a high level of lysosomal enzyme activity, and cathepsin D, the major enzyme responsible for proteolysis of the outer segments, is decreased in mutant RPE cells. Interestingly, our results also indicate a defect in the autophagy process in the Nuc1 RPE, which is probably also linked to impaired lysosomal function, because phagocytosis and autophagy might share common mechanisms in degradation of their targets. βA3/A1-crystallin is a novel lysosomal protein in RPE, essential for degradation of phagocytosed material.
The Wilmer Eye Institute, The Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287, USA.
J Samuel
JS
Zigler
Cheng
C
Zhang
Rhonda
R
Grebe
Gitanjali
G
Sehrawat
Laszlo
L
Hackler
Souvonik
S
Adhya
Stacey
S
Hose
D Scott
DS
McLeod
Imran
I
Bhutto
Walid
W
Barbour
Geetha
G
Parthasarathy
Donald J
DJ
Zack
Yuri
Y
Sergeev
Gerard A
GA
Lutty
James T
JT
Handa
Debasish
D
Sinha
D000818:Animals; D003459:Crystallins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010588:Phagosomes / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D055213:Retinal Pigment Epithelium / Q000378:metabolism* / Q000648:ultrastructure
D003459:Crystallins; C526189:betaA3-crystallin, rat
Biochim Biophys Acta. 2009 Apr;1793(4):605-14
19046998
Physiology (Bethesda). 2010 Feb;25(1):8-15
20134024
J Cell Sci. 1996 Feb;109 ( Pt 2):387-95
8838662
Nature. 1993 Feb 25;361(6414):724-6
8441466
J Cell Biol. 1967 Apr;33(1):61-72
6033942
J Mol Biol. 1991 Jan 20;217(2):373-88
1992168
Exp Eye Res. 2005 Mar;80(3):323-35
15721615
Nat Genet. 2000 Nov;26(3):270-1
11062461
J Biol Chem. 1993 Jul 25;268(21):15751-7
8340400
J Biol Chem. 1996 Aug 23;271(34):20536-9
8702796
Mol Biol Rep. 1999 Aug;26(3):201-5
10532316
Biochim Biophys Acta. 2009 Apr;1793(4):625-35
18977398
J Pathol. 2010 May;221(1):3-12
20225336
Proc Natl Acad Sci U S A. 2007 Jul 17;104(29):12005-10
17620600
J Cell Biol. 1968 Oct;39(1):169-84
5692679
J Cell Biol. 1969 Aug;42(2):392-403
5792328
Proc Natl Acad Sci U S A. 1997 Nov 25;94(24):12932-7
9371778
J Exp Med. 2004 Dec 20;200(12):1539-45
15596525
Biochim Biophys Acta. 1999 Oct 12;1434(2):331-46
10525151
Annu Rev Pharmacol Toxicol. 2007;47:469-512
16968212
J Histochem Cytochem. 1993 Feb;41(2):253-63
8419462
J Cell Biol. 2010 Jun 28;189(7):1059-70
20584912
Nature. 1983 Mar 31-Apr 6;302(5907):415-7
6835373
Invest Ophthalmol Vis Sci. 1994 Feb;35(2):568-79
8113008
Mol Vis. 2008;14:1872-85
18949065
Mol Ther. 2000 Nov;2(5):476-84
11082321
J Exp Med. 2001 Nov 5;194(9):1289-98
11696594
J Mol Biol. 1992 Jul 20;226(2):507-33
1640463
Invest Ophthalmol Vis Sci. 2010 Feb;51(2):1143-50
19741243
J Mol Biol. 1970 Mar;48(3):443-53
5420325
Hum Mol Genet. 2000 Mar 1;9(4):645-51
10699188
Mol Cell Neurosci. 2008 Jan;37(1):85-95
17931883
Nucleic Acids Res. 2001 May 1;29(9):e45
11328886
Trends Cell Biol. 2008 Oct;18(10):474-85
18774293
Nat Rev Mol Cell Biol. 2009 Sep;10(9):623-35
19672277
Prog Retin Eye Res. 2007 Jan;26(1):78-98
17166758
Exp Eye Res. 1992 May;54(5):821-3
1623969
J Mol Biol. 1994 Feb 25;236(3):918-39
8114102
J Mol Histol. 2011 Feb;42(1):59-69
21203897
Histochem Cell Biol. 2008 Mar;129(3):253-66
18274773
Cell Mol Life Sci. 2004 Jul;61(13):1664-74
15224189
Biochem J. 1997 Jun 15;324 ( Pt 3):935-40
9210419
FEBS Lett. 2010 Apr 2;584(7):1296-301
20188731
Physiol Rev. 2005 Jul;85(3):845-81
15987797
Nutr Rev. 2003 Oct;61(10):342-6
14604266
Biochemistry. 2009 Oct 13;48(40):9684-95
19746987
Nat Rev Mol Cell Biol. 2008 Oct;9(10):781-95
18813294