Targeting carbonic anhydrase in ageing

Increasing age brings frailty and disease with it. How and why we age are questions to which we don't yet have very good answers. Our approach is to examine the protein profiles of young and older tissues to see if there is a pattern to what changes with increasing years. Other ways to examine this question include extending our studies to other organisms. Bats for example are extremely long-lived considering their size and metabolic rate - how do their organs and tissues maintain good health for so long? We also look at animals that have outlasted the average for their species. In the case of Antarctic icefish, these are unique vertebrates in not having any haemoglobin to transport oxygen. Our cells use oxygen to generate ATP in mitochondria, how do the icefish live for so long without the assistance of oxygen carrying proteins. In addition we model the potential biochemical networks in cell culture systems to see whether we can understand the ageing process and how to modify it at the molecular level. All the work centres on energy production in cell and most specifically the mitochondrial organelle.
Mitochondrial dysfunction is a cellular hallmark of ageing. Carbonic anhydrases (CA) are a group of enzymes that we want to learn more about in the context of ageing. These enzymes are widespread in living organisms performing the crucial and reversible reaction converting carbon dioxide to bicarbonate and protons. Inhibitors of CA are already used in therapy for acute altitude sickness, glaucoma and under investigation for the potential to treat obesity and cancer.
Previously we have shown that Carbonic anhydrase 2 (CA2) levels are increased in mitochondrial fractions isolated from middle-aged mouse brain. We performed proteomic profiling in mitochondrial fractions from young and middle-aged mouse brain and muscle tissues. Several proteins were identified that changed significantly with age in each tissue type. Carbonic anhydrase (CA) isozymes II and III increased in quantity in older brain and skeletal muscle mitochondria respectively. We measured a concomitant increase in CA enzyme activity in older mitochondria. This increase is also apparent in degenerating brain and retina in the pcd5J mouse model of neurodegeneration(Chakrabarti et al., 2006), thus connecting increased CA with disease. We found increased CA levels cause a decrease in C. elegans lifespan. Others have shown that CA inhibitors (CAI) could have potential in the treatment of Alzheimer's disease (AD)(Fossati et al., 2015). A new connection between CAI, AD and mitochondrial toxicity has also been established(Solesio et al., 2018).
This project will focus on understanding how CA is involved in the process of ageing and how CA inhibitors might be a way to support healthy ageing. The methodologies to be used are rooted in protein biochemistry and mitochondrial physiology which together will give a picture of the ageing process and the results of targeting it to promote the chance of a longer healthspan.
Chakrabarti, L., Neal, J. T. J. T., Miles, M., Martinez, R. A. R. A., Smith, A. C. A. C., Sopher, B. L. B. L., et
al. (2006). The Purkinje cell degeneration 5J mutation is a single amino acid insertion that destabilizes Nna1 protein. Mamm. Genome 17, 103-10. doi:10.1007/s00335-005-0096-x.
Fossati, S., Giannoni, P., Solesio, M. E., Cocklin, S. L., Cabrera, E., Ghiso, J., et al. (2015). The carbonic anhydrase inhibitor methazolamide prevents amyloid beta-induced mitochondrial dysfunction and caspase activation protecting neuronal and glial cells in vitro and in the mouse brain. Neurobiol. Dis. 86, 29-40. doi:10.1016/j.nbd.2015.11.006.
Pollard, A., Shephard, F., Freed, J., Liddell, S., and Chakrabarti, L. (2016). Mitochondrial proteomic profiling reveals increased carbonic anhydrase II in aging and neurodegeneration. Aging (Albany.
NY). doi:10.18632/aging.101064.