July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018

The role of inositol phosphatase OCRL in microtubule nucleation: Implications for Oculocerebrorenal Syndrome of Lowe
Author Affiliations & Notes
  • Biao Wang
    Ophthalmology, Stanford University School of Medicine, Palo Alto, California, United States
  • Philipp p Prosseda
    Ophthalmology, Stanford University School of Medicine, Palo Alto, California, United States
  • Wei He
    Ophthalmology, Stanford University School of Medicine, Palo Alto, California, United States
  • Tia Judeen Kowal
    Ophthalmology, Stanford University School of Medicine, Palo Alto, California, United States
  • Jorge A. Alvarado
    Ophthalmology, Stanford University School of Medicine, Palo Alto, California, United States
  • Ke Ning
    Ophthalmology, Stanford University School of Medicine, Palo Alto, California, United States
  • Yang Sun
    Ophthalmology, Stanford University School of Medicine, Palo Alto, California, United States
    Palo Alto VA Medical Center, Palo Alto, California, United States
  • Footnotes
    Commercial Relationships   Biao Wang, None; Philipp Prosseda, None; Wei He, None; Tia Kowal, None; Jorge Alvarado, None; Ke Ning, None; Yang Sun, None
  • Footnotes
    Support  NIH/NEI K08-EY022058 (Y.S.), R01-EY025295 (Y.S.), VA merit CX001298 (Y.S.), Ziegler Foundation for the Blind (Y.S.), Research for Prevention of Blindness Unrestricted grant (Stanford), Lowe syndrome association (Y.S.), NEI P30 grant (Stanford)
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 3082. doi:
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      Biao Wang, Philipp p Prosseda, Wei He, Tia Judeen Kowal, Jorge A. Alvarado, Ke Ning, Yang Sun;
      The role of inositol phosphatase OCRL in microtubule nucleation: Implications for Oculocerebrorenal Syndrome of Lowe. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3082.

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

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Abstract

Purpose : Inositol phosphatases are important regulators of cell signaling, polarity, and vesicular trafficking. Mutations in OCRL, an inositol polyphosphate 5-phosphatase which dephosphorylates PI(4,5)P2 to PI4P, results in Oculocerebrorenal syndrome of Lowe, an X-linked recessive disorder that presents with congenital cataracts, glaucoma, renal dysfunction and brain abnormalities. The function of OCRL in causing cataracts and glaucoma is not well understood. During cell division, microtubules are nucleated from the centrosome and are transport to other locations in the cell by molecular motors. Impairments in structural support, including modified cytoskeletal proteins, and microtubule-organization elements, could be initiating factors in congenital cataract and glaucoma pathogenesis. The purpose of this study is to investigate the role of OCRL mediated microtubule nucleation in the pathogenesis of the ocular phenotypes of Lowe syndrome.

Methods : Knockdown of OCRL in human retinal pigmented epithelial (RPE) cell lines was performed using Lentiviral CRISPR/cas9/OCRL. Immunofluorescence was performed to investigate the localization of OCRL and PI(4,5)P2 in RPE and Lowe syndrome patient fibroblast. Fluorescence-activated cell sorting was performed to detect the cell cycle progression.

Results : Our experiments revealed that OCRL localized to centrosome both in interphase and mitosis in RPE cells, indicating it may be involved in centrosome function. Lowe patient cells were observed to have significantly slower cell cycle progression, in comparison to normal human fibroblast. We also found OCRL knockdown RPE cells exhibited slower proliferation rate compared to wild type RPE cells. Notably, deficient of OCRL in patient fibroblasts and Ocrl knockdown cells resulted in an redistribution of PI(4,5)P2. Interestingly, Lowe patient fibroblasts demonstrated impaired microtubule network, which suggested a role of inositol phospholipid in microtubule network formation.

Conclusions : OCRL is localized to centrosome and regulates centrosomal phosphoinositide homeostasis, which may play critical roles on microtubule nucleation by which to control cell cycle progression.

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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