Corneal keratin aggresome (CKAGG) formation and clearance by proteasome activation

Fawzia Bardag-Gorce; Andrew Makalinao; Imara Meepe; Richard H. Hoft; Daileen Cortez; Joan Oliva; Amanda Laporte; Jeremy Stark; Amber Gorce; Michael Di Lorenzo; Samuel W. French; William Lungo; Yutaka Niihara

Heliyon (Dec 2018)

Corneal keratin aggresome (CKAGG) formation and clearance by proteasome activation

Fawzia Bardag-Gorce,
Andrew Makalinao,
Imara Meepe,
Richard H. Hoft,
Daileen Cortez,
Joan Oliva,
Amanda Laporte,
Jeremy Stark,
Amber Gorce,
Michael Di Lorenzo,
Samuel W. French,
William Lungo,
Yutaka Niihara

Affiliations

Fawzia Bardag-Gorce: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA; Corresponding author.
Andrew Makalinao: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
Imara Meepe: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
Richard H. Hoft: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
Daileen Cortez: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
Joan Oliva: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA; Emmaus Medical, Inc. 21250 Hawthorne Blvd. Suite 800, Torrance, CA, 90503, USA
Amanda Laporte: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
Jeremy Stark: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
Amber Gorce: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
Michael Di Lorenzo: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
Samuel W. French: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
William Lungo: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA
Yutaka Niihara: Los Angeles BioMedical Research Institute, Torrance, CA, 90502, USA; Emmaus Medical, Inc. 21250 Hawthorne Blvd. Suite 800, Torrance, CA, 90503, USA

Journal volume & issue: Vol. 4, no. 12
p. e01012

Abstract

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Purpose: To understand the mechanism of corneal keratin expression and clearance in corneal epithelium with Limbal Stem Cell Deficiency (LSCD). The hypothesis is that LSCD-induced proteasome dysfunction is a contributing factor to keratin aggregation, causing corneal keratin aggresome (CKAGG) formation. Method: LSCD was surgically induced in rabbit corneas. LSCD corneal epithelial cells (D-CEC) were collected to investigate keratin K4 and K13 expression and CKAGG formation. Oral mucosal epithelial cells (OMECS) were isolated and cultured to study K4 and K13 expression. Cultured cells were treated with proteasome inhibitor to induce CKAGG formation. Results: K4 and K13 were strongly expressed in D-CEC, with additional higher molecular weight bands of K4 and K13, suggesting CKAGG formation. Double staining of K4/K13 and ubiquitin showed co-localization of these keratins with ubiquitin in D-CEC. Proteasome inhibition also showed K4/K13 modification and accumulation in cultured OMECS, similar to D-CEC. Proteasome activation was then performed in cultured OMEC. There was no accumulation of keratins, and levels of unmodified keratins were found significantly reduced. Conclusion: Results showed an abnormal expression of K4 and K13 after LSCD-induced proteasome dysfunction, which coalesce to form CKAGG in Corneal Epithelial Cells (CEC). We propose that CKAGG formation may be one of the causative factors of morphological alterations in the injured corneal epithelium, and that CKAGG could potentially be cleared by enhancing proteasome activity.

Published in Heliyon

ISSN: 2405-8440 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Science: Science (General); Social Sciences: Social sciences (General)
Website: https://www.cell.com/heliyon/home

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