Research Groups

Cell biology and Biotechnology

Dr Jose Antonio Sánchez-Alcazar. UPO
Programmed cell death during development and disease
Dr Jose Antonio Sánchez-Alcazar. UPO
Principal Investigator

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 The Apoptotic microtubule network during the execution phase of apoptosis

It has recently been shown that the microtubule cytoskeleton is reformed during the execution phase of apoptosis forming an apoptotic microtubule network (AMN). AMN is closely associated with the plasma membrane, forming a cortical ring or cellular “cocoon”. Concomitantly other components of the cytoskeleton, such as actin and cytokeratin filaments disassemble. Previously, we have demonstrated that this microtubule reformation occurs in many cell types and under different apoptotic stimuli. Our working hypothesis proposes that AMN is required to maintain plasma membrane integrity and cell morphology during the execution phase of apoptosis. AMN disruption leads cells to secondary necrosis, release of toxic molecules, and it might damage neighbours cells. Therefore, AMN formation in apoptosis during development and adult organisms is essential for tissue homeostasis in multicelullar organisms. We will generate different models expressing fluorescent actin and tubulin to study the reorganization of actin filaments and microtubules in vivo. In these models we will look for the signaling pathways involved on AMN formation. To study AMN nucleation, whose molecular mechanism is unknown, we will study AMN components and associated proteins, and we will evaluate their particular contribution to AMN formation. Moreover, we will study whether AMN maintenance dependent on mitochondrial function, and the effects of cytoskeleton reorganization on mitochondrial function and dynamics. Finally, we will study the role of AMN in the context of a multicelullar organism during developmental apoptosis. We will generate a Drosophila transgenic strain expressing a mutant tubulin with the cleavage consensus sequence of caspases (DEVD). In this transgenic strain, we expect that mutant tubulin will be degraded by caspases, microtubules disorganized, and the formation of AMN will be impaired during the execution phase of apoptosis. We will look for abnormalities in normal development in this transgenic strain.
In summary, we propose the development of different molecular and cellular approaches to better know the formation, dynamics, coordination and function of AMN during the execution phase of apoptosis.

 Molecular and physiopathological mechanisms of mitophagy in mitochondrial diseases

Coenzyme Q10 (CoQ) deficiencies have a great relevance due to its high prevalence, easy diagnosis, and efficient treatment. More than ten genes have been identified in the human nuclear genome required for CoQ biosynthesis (COQ genes). Mutations in these genes induce primary CoQ deficiency with different clinical manifestations. Secondary CoQ deficiencies have been found in a wide spectrum of diseases including, mitochondrial diseases with mutations in both mitochondrial DNA or nuclear DNA, neurodegenerative diseases such as Parkinson, fibromyalgia, cancer, and in patients under statin treatment. We hypothesize that CoQ deficiency alters mitochondrial function, and induce increase oxidative stress, and the activation of mitochondrial permeability transition, which triggers the selective degradation of impaired mitochondria by mitophagy. To demonstrate it, we will work with fibroblasts derived from patients with mitochondrial diseases with primary o secondary CoQ deficiency, and with animal models of mitochondrial diseases with CoQ deficiency generated by us. As model of primary deficiency, we will generate Caenorhabditis elegans strains with COQ genes mutated or silenced by RNAi. As secondary CoQ deficiency, we will work with Caenorhabditis elegans strains by silencing mitochondrial citochrome c oxidase assembly genes. In these models, we will study mitophagy in muscular and nervous tissues which are the most affected in CoQ deficiencies.