Degree Name

PhD (Doctor of Philosophy)

Program

Biomedical Sciences

Date of Award

8-2018

Committee Chair or Co-Chairs

Gary Wright, Jonathan Peterson

Committee Members

Kenneth Ferslew, Krishna Singh, Stacy Brown, Douglas Thewke

Abstract

Changes to the metabolism of the cardiomyocyte are driven by complex signaling pathways in order to adjust to stress. For instance, HIF-1α is classically known to upregulate glycolytic metabolism to compensate for oxygen deficiency. Other important effects upon glucose metabolism, which we investigate here more extensively, were also observed. Hearts derived from mice with the cardiac-restricted expression of a stabilized form of HIF-1α are remarkably ischemia stress-tolerant. Here, stable isotope-resolved metabolomic analyses were utilized to investigate glucose cardiometabolism remodeling by HIF-1αduring ischemia. We found that 13C-lactate accumulation was significantly elevated in HIF-1α expressing hearts while paradoxically glycogen was maintained to a remarkable extent during an ischemic time course. These findings suggested an unexpected source of glucose in HIF-1α hearts during global ischemia. Accordingly, the presence of gluconeogenesis in hearts was evaluated. Indeed, gluconeogenic intermediates (i.e. m+3) including glucose-6-phosphate [m+3], fructose-6-phosphate [m+3], and fructose 1,6-bisphosphate [m+3] were observed at significantly elevated levels in the ischemic HIF-1α heart. Collectively, these data establish the surprising finding that HIF-1α supports active gluconeogenesis in the heart during ischemia.

As less is known regarding the effects of CTRP3 we first tested whether CTRP3 overexpression would protect the ischemic heart. Our data indicate that CTRP3 failed to confer ischemic tolerance in heart ex vivo. However,we were able to show that CTRP3 protected the liver from lipid-induced stress and prevented hepatic lipid accumulation. To further investigate the mechanisms of hepatic protective effect mediated by CTRP3, we identified the receptor and established that CTRP3 increases oxygen consumption in response to lipid overloaded. Lysosomal-associated membrane protein 1 (LAMP-1),

In summary, these data indicate that targeted metabolic rearrangements within cardiomyocyte/hepatocyte holds promise for the alleviation of common pathological conditions.

Document Type

Dissertation - Open Access

Copyright

Copyright by the authors.

Included in

Biochemistry Commons

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