Solo, Keaton
(2024)
The Therapeutic Application of Medium Chain Acylcarnitines for Genetic Disorders of Long Chain Fatty Acid Oxidation.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Medium chain fatty acids (MFA) are commonly used as oral therapeutics to correct energy deficits causes by genetic long-chain fatty acid oxidation disorders (LCFAOD); however, patients taking medium chain fatty acid therapies often continue to experience hospitalization due to rhabdomyolysis. Before fatty acids of any chain length can be shortened and utilized to produce cellular energy through ß-oxidation, the free fatty acid must be conjugated to coenzyme A (CoA) to allow acyl-CoA production. The fatty acid chain length specific enzyme family known as acyl-CoA synthetases catalyze this necessary reaction. We show the five known medium-chain acyl-CoA synthetases (ACSMs) are expressed in the liver and the kidney but not in the skeletal muscle or heart tissue. Two pre-clinical mouse models of LCFAODs were used to show that current medium chain fatty acid therapies are ineffective in tissues lacking ACSMs. We demonstrate in vivo and in vitro that without the expression of the ACSMs, medium chain fatty acids are inefficiently oxidized through the carnitine shuttle and long-chain fatty acid enzymatic pathway. In testing the oral bioavailability of medium-chain therapies, we found that most of the oral treatment is taken up by the liver and does not reach the blood stream for systemic therapeutic use.
Carnitine-O-acetyltransferase (CrAT) is a mitochondrial enzyme shown to reversibly react short and medium-chain carnitines to their CoA conjugate forms and vice versa to balance cellular pools of free-carnitine and free-CoA in support of the ß-oxidation pathway. We show that CrAT is robustly expressed in the skeletal muscle and heart. Liver expresses very low levels of CrAT, allowing oral doses of medium-chain carnitines to partially escape first-pass liver metabolism and reach systemic circulation. We exploited CrAT’s expression profile and activity, testing the therapeutic potential of medium-chain carnitines against skeletomuscular symptoms of LCFAOD using three preclinical LCFAOD mouse models in both in vivo and in vitro experiments. Additional studies were performed with non-human primate tissue, wild type mice, and human cell lines, demonstrating treatment efficacy in near-human models. Finally, we demonstrate the therapeutic effects of medium-chain carnitines are ablated in the absence of CrAT, using a CrAT deficient mouse model.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
18 December 2024 |
| Date Type: |
Publication |
| Defense Date: |
4 October 2024 |
| Approval Date: |
18 December 2024 |
| Submission Date: |
15 November 2024 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
158 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Public Health > Human Genetics |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Fatty acid oxidation
metabolism
human genetics
rhabdomyolysis
oral supplementation
bioavailability |
| Date Deposited: |
18 Dec 2024 20:15 |
| Last Modified: |
18 Dec 2024 20:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/47083 |
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