Resumen de Paper de la metacaspasa atmc1 en la formació d’agregats de proteïnes desencadenats per estrès en llevats i plantes
Protein aggregation is a widespread phenomenon in cells that can be associated with pathological conditions. The formation of protein aggregates is induced by multiple types of stress, including thermal, chemical, nutrient deficiency and aging. However, the machinery that the formation and deposition of misfolded proteins into specific deposition sites is poorly understood in plants.
Metacaspases are critical regulatory factors that have been shown to participate in cell death and cell survival processes. For example, the Saccharomyces cerevisiae metacaspase ScMCA1 has been shown to be important for maintaining cellular proteostasis and limiting protein aggregation. Similarly, the Arabidopsis thaliana metacaspase AtMC1, acts both as a positive regulator of pathogen-triggered programmed cell death and also has a pro-survival homeostatic function in aging plants in parallel to a similar pro-survival function of autophagy.
In this thesis, we have used yeast model system to analyze the role of AtMC1 in protein aggregation. Our results show that the plant AtMC1 co-localized with aggregate markers into aggregate deposition sites in yeast during stress and aging. AtMC1 is required for efficient removal of terminally unfolded proteins in yeast and this role is evolutionarily conserved.
In addition, taking advantage of the extensive knowledge of protein quality control and protein aggregation in yeast, we have generated and characterized new markers of protein aggregation in plants. We have identified the Arabidopsis orthologues of yeast protein aggregate marker ScHSP104 and ScUBC9TS, AtHSP101 and AtSCE1TS. Using these markers, we have characterized the function of AtMC1 in process of stress-triggered protein aggregation in plants. Our results show that the lack of AtMC1 leads to an increase in the accumulation of proteins aggregates during heat stress and pathogen attack. We also found that AtMC1 co-localizes and co-immunoprecipitates with AtHSP101 in planta.
In summary, this work provides a deeper insight of AtMC1 function in protein quality control in plants. These data may contribute to the elucidation of the mechanisms controlling protein aggregation in plants that can help developing new strategies to fight against environmental stresses in the field.
