Carbon monoxide, autophagy and cytoprotection in response to cerebral ischemia

Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina

There is an increasing need for promoting neuroprotection against cerebral ischemia, which is the main cause of brain damage in adults. Astrocytes are the most abundant cells inboard the central nervous system (CNS), being known as key glial cell for promoting neuronal survival and homeostasis. It is more established in nowdays that astrocytic dysfunction contributes to neurodegenerative processes. Although, carbon monoxide is a well renown as a lethal and toxic gas due to its high affinity to hemoglobin, CO exerts anti-apoptotic, anti-inflammatory and anti-proliferative functions. Recent studies showed likewise that CO induces autophagy, promoting therefore cytoprotective and anti-inflammatory effects. Autophagy is a major catabolic pathway, known as an autodigestive process that degrades cellular organelles and proteins, playing an important role in cellular homeostasis during environmental stress. Due to the great interest on the signaling and cytoprotective actions of CO, novel strategies have been put forward to exploit the potential therapeutic effects of this gaseous molecule. One of these approaches consist on the development of CO-releasing molecules (CO-RMs), compounds that deliver small quantities of CO to tissues and first identified by the group of Motterlini and co-workers. The aim of this Master thesis was to study the action of CORM-A1, a boron-containing compound that spontaneously releases CO, against cell death in primary culture of astrocytes. In particular, we examined the role of CORM-A1 in autophagy, mitophagy and cell metabolism. Here, we demonstrated that CORM-A1 promotes the induction of autophagy in primary culture of astrocytes. Furthermore,autophagy is directly involved in the cytoprotective effect of CORM-A1 against cell death. In some preliminary experiments we have shown that CORM-A1 also induced mitophagy, while autophagy and inhibition of cell death promoted by CORM-A1 seem to occur under hypoxia (5% of oxygen). This master thesis has addressed several important questions on the role of CO in astrocyte function but also opened to many other important questions on the mechanism of action of CO. For instance, future work must be undertaken in order to explore whether CO-mediated induction of reactive oxygen species (ROS), which play an important role in cell signaling, which are the factors directly involved in mitophagy and the cross-talk between apoptosis and modulation of autophagy.

e-COST,(COST Action BM1005)