July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Effects of Chlorogenic acid on Lysosomal Function and Autophagy in Retinal Pigment Epthelial Cells.
Author Affiliations & Notes
  • Mallika Valapala
    Optometry, Indiana University, Bloomington, Indiana, United States
  • Hsuan-Yeh Pan
    Optometry, Indiana University, Bloomington, Indiana, United States
  • Kristen Renee Hatton
    Optometry, Indiana University, Bloomington, Indiana, United States
  • Footnotes
    Commercial Relationships   Mallika Valapala, None; Hsuan-Yeh Pan, None; Kristen Renee Hatton, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 4023. doi:
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      Mallika Valapala, Hsuan-Yeh Pan, Kristen Renee Hatton; Effects of Chlorogenic acid on Lysosomal Function and Autophagy in Retinal Pigment Epthelial Cells.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4023.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : The Retinal Pigmented Epithelium (RPE) serves many physiological roles crucial for maintaining homeostasis of the retina. RPE is the most active phagocytic cell in the body, phagocytosing 10% of the photoreceptor volume daily. Autophagy-mediated cellular clearance is crucial for the proper functioning of the RPE. The terminal events of both phagocytosis and autophagy involve fusion and subsequent degradation in the lysosomes. Dysfunctional lysosomes lead to impaired cellular clearance and subsequent degeneration of the RPE. Transcription Factor EB (TFEB) is identified as a master regulator of lysosomal function and autophagy. A serine/threonine protein phosphatase, calcineurin is known to promote nuclear translocation and activation of TFEB. We investigated the effects of chlorogenic acid, a calcineurin activator on the TFEB-mediated regulation of lysosomal and autophagy pathway in the RPE.

Methods : ARPE-19 cells were treated with chlorogenic acid (5 mM and 10 mM) for 24 and 48 hr. Calcineruin activity was measured in the presence of chlorogenic acid. Quantitative real time PCR (qPCR) analysis was performed to study the expression of the following genes: Lysosome associated membrane protein 1(LAMP-1), Cathepsin D (CTSD), Mucolipin 1 (MCON1), and BECN1 (Beclin 1). Immunoblotting and immunostaining with Transcription Factor EB (TFEB) antibody was used to examine TFEB protein level and localization of TFEB. Microtubule-associated protein 1A/1B-light chain 3 (LC3) antibody was used to study the autophagy pathway.

Results : Calcineurin activity was induced in the presence of chlorogenic acid. qPCR analysis of ARPE-19 cells, showed upregulation of TFEB-target genes in the autophagy and lysosomal pathway upon treatment with chlorogenic acid. Concomitantly, nuclear translocation of TFEB was observed. Immunostaining and immunoblotting of LC3 antibody showed increased levels of LC3 II in the presence of chlorogenic acid.

Conclusions : Our studies suggest that pharmacological upregulation of calcineurin activity by chlorogenic acid, induces nuclear localization of TFEB and expression of TFEB target genes in the RPE. Our data suggests that agents that promote nuclear localization of TFEB play a crucial role in upregulation of cellular clearance via autophagy in the RPE.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

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