Abstract

Lipotoxicity (LTx) is involved in mostly every process of neuronal injury. Using NGFDPC12 cells we show that palmitic acid (PA) induces the expression of stress response genes HIF-1α and BNIP3, increases the accumulation of reactive oxygen species, and decreases cell viability by apoptosis. Inhibition of cathepsins does not rescue neurons from PA-LTx but inhibition of necroptosis and promotion of autophagy do. DHA decreases the expression of HIF-1α and BNIP3 and rescues PA-induced cell death by inhibiting apoptosis and necroptosis. Besides DHA stimulates the mRNA expression, phosphorylation and conjugation of autophagy controlling proteins. Inhibiting autophagy during DHA treatment decreases its capacity to rescue cells from PA-LTx. PA-induced ROS also stimulate the expression of EFABP that could be prevented by co-treating the cells with the antioxidant N-Acetyl-Cystein during PA-LTx. Conversely lowering EFABP expression by siRNA increases the accumulation of ROS and decreases cell viability but stimulating PPARβ and PPARγ with direct agonists increases the expression of EFABP and increases cell viability during PA-LTx.

As a parallel study .5% [O2] hypoxia induces the expression of the same stress response genes and triggered apoptosis in NGFDPC12 cells just like PA-LTx. Hypoxia disrupts the architecture of NGFDPC12 cells microscopically by diminishing the body size, reducing the confluency, thinning the neurites and producing apoptotic bodies. The decrease in cell viability can be prevented with an array of different concentration of DHA and the autophagy promoter rapamycin just like in PA-LTx. Pre-treatment of NGFDPC12 cells with DHA and EPA (another PUFA) increases cell viability under hypoxia. As in PA-LTx hypoxia also induces ROS and can be prevented with antioxidant MCI-186. The mRNA and protein level of FABP5 are also increased under hypoxia and can be prevented by co-treatment with antioxidant. Lastly the hypoxia-induced expression of EFABP can be inhibited by antagonizing PPARγ.

LLU Discipline

Physiology

Department

Basic Sciences

School

School of Medicine

First Advisor

Marino A. De Leon

Second Advisor

Carlos A. Casiano

Third Advisor

Johnny D. Figueroa

Fourth Advisor

Anthony F. Firek

Fifth Advisor

William H. R. Langridge

Degree Name

Doctor of Philosophy (Medical Science)

Degree Level

Ph.D.

Year Degree Awarded

2018

Date (Title Page)

9-2018

Language

English

Library of Congress/MESH Subject Headings

Autophagy--physiology; Docosahexaenoic acid; Hypoxia--Pathophysiology; Palmitic acid--Metabolism.

Subject - Local

Autophagy; Docosahexaenoic acid; Epidermal fatty acid binding Protein; Hypoxia; Necroptosis; Palmitic acid lipotoxicity

Type

Dissertation

Page Count

210 p.

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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