Amyotrophic lateral sclerosis (ALS) is the most common form of adult onset motor neuron disease and is characterized by the progressive degeneration and death of motor neurons. The pathologic mechanisms underlying ALS are poorly understood although our laboratory identified decreased levels of transthyretin (TTR), a protein that impacts the retinoid signaling pathway, in the cerebrospinal fluid of ALS patients. Differential expression of retinoid signaling components has been reported in ALS patients and transgenic animal models of familial ALS. We sought to further characterize TTR and retinoid signaling proteins in ALS and to evaluate the role of retinoid signaling in motor neuron cell death.
Mass spectrometry and immunoblotting were used to investigate TTR. Immunohistochemistry using lumbar spinal cord tissue from ALS patients and non-neurologic disease controls was used to characterize retinoid signaling pathway proteins. Spinal cord tissue homogenates were used for co-immunoprecipitation studies and electrophoretic mobility shift assays. Motor neuron-enriched cultures established from embryonic day 14 rats were utilized for in vitro studies. RAR-mediated signaling was modulated with pan-agonists and isotype-specific agents and hydrogen peroxide used to model oxidative stress/injury.
Altered post-translational modifications and high molecular weight species of the TTR protein were observed in ALS. Cellular retinoic acid binding protein-II (CRABP-II) and retinoic acid receptor beta (RARβ) exhibited increased nuclear localization in motor neurons of sporadic ALS patients. Protein-protein interactions (between CRABP-II and RARα or RARβ) did not differ although retinoic acid response element binding was increased in ALS as compared to controls. Treatment with a pan-RAR or RARβ-specific agonist significantly decreased oxidative stress-induced motor neuron cell death in vitro and genes downstream of RARβ were increased with treatment.
Our results indicate that TTR genetic polymorphisms do not represent a novel susceptibility factor for ALS, although protein modification and aggregation appear to be altered in ALS. Localization of proteins of the retinoid signaling pathway is altered in ALS patients and these changes translate to the transcriptional level. Our in vitro work indicates that stimulating the RARs (particularly RARβ) is neuroprotective and that pharmacologic agents that target this nuclear receptor may be of value in slowing the progression of ALS.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-08262010-150252 |
| Date | 27 August 2010 |
| Creators | Kolarcik, Christi L |
| Contributors | Kacey G. Marra, Ph.D., Charleen T. Chu, M.D., Ph.D., Michael J. Zigmond, Ph.D., Robert Bowser, Ph.D., Satdarshan P.S. Monga, M.D. |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-08262010-150252/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0018 seconds