“Learning to die is also learning how to live.”
Morris Schwartz, Professor of Sociology (1916-1995)
Programmed cell death (PCD) has a paramount role in eukaryotic development and disease control. As plant and animal lineages diverged over one billion years ago, their extant phyla exhibit marked differences in molecular regulation, physiological roles and morphology of PCD. Particularly remarkable is that plants utilize their dying cells and cell corpses to perform a number of fundamental physiological processes; for example to feed young embryo (suspensor cells), to feed and water the whole plant (vascular elements in phloem and xylem), to store nutrients in a seed (endosperm cells) or to protect tree stems from physical injury (the outer cell layers of the bark).
Plant genomes do not encode direct homologues of core regulators of apoptotic PCD found in animals. Further- more, the presence of rigid cell walls and lack of phagocytic cells in plants exclude breakdown of cells into membrane-surrounded bodies and their engulfment typical for apoptosis. Morphological ways of plant PCD are classified into two broad classes: vacuolar cell death and necrosis.
Molecular components of plant cell death regulation are beginning to emerge. In our laboratory, we study how particular gene/protein acts in the pathway leading to cell death using spruce somatic embryos and Arabidopsis plants as model systems.
In particular, we address mechanistic role of meta- caspases (proteases ancestral to animal caspases) and autophagy-related proteins in making decision which way of cell demise, vacuolar or necrotic, will be chosen by the suicidal cell.
Peng Zhao, Xue-mei Zhou, Li-yao Zhang, Wei Wang, Li-gang Ma, Li-bo Yang, Xiong-bo Peng, Bozhkov PV, Meng-xiang Sun. (2013) A bipartite molecular module controls cell death activation in the basal cell lineage of plant embryos. PLOS Biol 11(9): e1001655. doi:10.1371/journal.pbio.1001655.
Minina EA, Sanchez-Vera V, Moschou PN, Suarez MF, Sundberg E, Weih M and Bozhkov PV. (2013) “Autophagy mediates caloric restriction-induced lifespan extension in Arabidopsis”. Aging Cell 12: 327-329.
Moschou PN, Smertenko AP, Fukada K, Savenkov EI, Minina EA, Robert S, Hussey PJ, Bozhkov PV (2013) “The Caspase-Related Protease Separase (EXTRA SPINDLE POLES) Regulates Cell Polarity and Cytokinesis in Arabidopsis”. Plant Cell 25: 2171-2186
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Bozhkov, Peter V, Maria F Suarez, Lada H Filonova, Geoffrey Daniel, Andrey A Zamyatnin, Salvador Rodriguez-Nieto, Boris Zhivotovsky, and Andrei Smertenko. 2005. “Cysteine protease mcII-Pa executes programmed cell death during plant embryogenesis.” Proceedings of the National Academy of Sciences of the United States of America 102 (40) (October 4): 14463-8. doi:10.1073/pnas.0506948102.
Suarez, Maria F, Lada H Filonova, Andrei Smertenko, Eugene I Savenkov, David H Clapham, Sara von Arnold, Boris Zhivotovsky, and Peter V Bozhkov. 2004. “Metacaspase-dependent programmed cell death is essential for plant embryogenesis.” Current biology : CB 14 (9) (May 4): R339-40. doi:10.1016/j.cub.2004.04.019.