Cited by 144Autophagy in Disease and TherapyRetinal Diseases and TreatmentsCellular transport and secretion

Lysosomal-mediated waste clearance in retinal pigment epithelial cells is regulated by CRYBA1/βA3/A1-crystallin via V-ATPase-MTORC1 signaling

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Valapala, Mallika, Wilson, Christine, Hose, Stacey, Bhutto, Imran A, Grebe, Rhonda, Dong, Aling, Greenbaum, Seth, Gu, Limin +12 more·2014·Autophagy

Abstract

In phagocytic cells, including the retinal pigment epithelium (RPE), acidic compartments of the endolysosomal system are regulators of both phagocytosis and autophagy, thereby helping to maintain cellular homeostasis. The acidification of the endolysosomal system is modulated by a proton pump, the V-ATPase, but the mechanisms that direct the activity of the V-ATPase remain elusive. We found that in RPE cells, CRYBA1/βA3/A1-crystallin, a lens protein also expressed in RPE, is localized to lysosomes, where it regulates endolysosomal acidification by modulating the V-ATPase, thereby controlling both phagocytosis and autophagy. We demonstrated that CRYBA1 coimmunoprecipitates with the ATP6V0A1/V0-ATPase a1 subunit. Interestingly, in mice when Cryba1 (the gene encoding both the βA3- and βA1-crystallin forms) is knocked out specifically in RPE, V-ATPase activity is decreased and lysosomal pH is elevated, while cathepsin D (CTSD) activity is decreased. Fundus photographs of these Cryba1 conditional knockout (cKO) mice showed scattered lesions by 4 months of age that increased in older mice, with accumulation of lipid-droplets as determined by immunohistochemistry. Transmission electron microscopy (TEM) of cryba1 cKO mice revealed vacuole-like structures with partially degraded cellular organelles, undigested photoreceptor outer segments and accumulation of autophagosomes. Further, following autophagy induction both in vivo and in vitro, phospho-AKT and phospho-RPTOR/Raptor decrease, while pMTOR increases in RPE cells, inhibiting autophagy and AKT-MTORC1 signaling. Impaired lysosomal clearance in the RPE of the cryba1 cKO mice also resulted in abnormalities in retinal function that increased with age, as demonstrated by electroretinography. Our findings suggest that loss of CRYBA1 causes lysosomal dysregulation leading to the impairment of both autophagy and phagocytosis.

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  • Endolysosomal acidification is thought to be regulated by direct interaction of βA3/A1-crystallin with lysosomal v-ATPase.

    “Endolysosomal acidification is thought to be regulated by direct interaction of βA3/A1-crystallin with lysosomal v-ATPase (Valapala et al., 2014).”

    From The cell biology of the retinal pigment epithelium (2020) · cites this paper as Valapala et al., 2014

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Authors
Valapala, M., Wilson, C., Hose, S., Bhutto, I. A., Grebe, R., Dong, A., Greenbaum, S., Gu, L., Sengupta, S., Cano, M., Hackett, S., Xu, G., Lutty, G. A., Dong, L., Sergeev, Y., Handa, J. T., Campochiaro, P., Wawrousek, E., Zigler, Jr., & Sinha, D.
Affiliations
  • Johns Hopkins University (US)
  • Tongji University (CN)
  • National Institutes of Health (US)
Corresponding author
Sinha, Debasish
Venue
Autophagy
Published
2014-01-23
Volume
10
Issue
3
Pages
480-496
ISSN
  • 1554-8627 (ISSN-L)
  • 1554-8635
OpenAlex
W2089525975
Cited by
144
References
70
Citations by year
2026: 7 · 2025: 10 · 2024: 13 · 2023: 13 · 2022: 11 · 2021: 11 · 2020: 17 · 2019: 9 · 2018: 14 · 2017: 6 · 2016: 10 · 2015: 17 · 2014: 6
FWCI
9.82
Type
journal article
Language
en
Open access
Licence
cc-by-nc
Locations
  • Autophagy (publishedVersion, cc-by-nc)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
Funders
  • Research to Prevent Blindness
  • National Eye Institute (R01EY019037, EY14005, R01EY014005, #EY01765, EY019037-S, P30EY001765, R01EY019904)
Topics
  • Health Sciences › Medicine › Epidemiology › Autophagy in Disease and Therapy
  • Health Sciences › Medicine › Ophthalmology › Retinal Diseases and Treatments
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Cellular transport and secretion
Keywords
retinal pigment epithelium, lysosomal acidification, V-ATPase, mTORC1 signaling, phagocytosis, lysosomal pH, cathepsin D, lipid droplet accumulation, retinal degeneration, electroretinogram
MeSH terms
Mechanistic Target of Rapamycin Complex 1, Animals, Autophagy, Crystallins, Lysosomes, Phagocytosis, Phagosomes, Signal Transduction, Mice, Knockout, Vacuolar Proton-Translocating ATPases, Multiprotein Complexes, Mice, Rats, Retinal Pigment Epithelium, TOR Serine-Threonine Kinases

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