Factors regulating dynamics of chromatin structure have direct impact on expression of genetic in... more Factors regulating dynamics of chromatin structure have direct impact on expression of genetic information. Cohesin is a multi-subunit protein complex crucial for pairing sister chromatids during cell division, DNA repair and regulation of gene transcription and silencing. In non-plant species cohesin is loaded on chromatin by the Scc2/Scc4 (NIBPL/MAU2) complex. Here we identify AtSCC4, the Arabidopsis homolog of Scc4, and show that it forms a functional complex with AtSCC2, the homolog of Scc2. We demonstrate that AtSCC2 and AtSCC4 act in the same pathway and that both proteins are indispensable for cell fate determination during early stages of embryo development. Mutant embryos lacking either of these proteins develop only up to the globular stage, and show suspensor over-proliferation phenotype preceded by ectopic auxin maxima distribution. We further establish a new assay to reveal the AtSCC4-dependent dynamics of cohesin loading on chromatin in vivo. Our findings define Scc2/S...
In the animal life cycle, the earliest manifestations of programmed cell death (PCD) can already ... more In the animal life cycle, the earliest manifestations of programmed cell death (PCD) can already be seen during embryogenesis. The aim of this work was to determine if PCD is also involved in the elimination of certain cells during plant embryogenesis. We used a model system of Norway spruce somatic embryogenesis, which represents a multistep developmental pathway with two broad phases. The first phase is represented by proliferating proembryogenic masses (PEMs). The second phase encompasses development of somatic embryos, which arise from PEMs and proceed through the same sequence of stages as described for their zygotic counterparts. Here we demonstrate two successive waves of PCD, which are implicated in the transition from PEMs to somatic embryos and in correct embryonic pattern formation, respectively. The first wave of PCD is responsible for the degradation of PEMs when they give rise to somatic embryos. We show that PCD in PEM cells and embryo formation are closely interlinke...
Vacuolar programmed cell death (PCD) is indispensable for plant development and is accompanied by... more Vacuolar programmed cell death (PCD) is indispensable for plant development and is accompanied by a dramatic growth of lytic vacuoles, which gradually digest cytoplasmic content leading to self-clearance of dying cells. Our recent data demonstrate that vacuolar PCD critically requires autophagy and its upstream regulator, a caspase-fold protease metacaspase. Furthermore, both components lie downstream of the point of no return in the cell-death pathway. Here we consider the possibilities that i) autophagy could have both cytotoxic and cytoprotective roles in the vacuolar PCD, and ii) metacaspase could augment autophagic flux through targeting an as yet unknown autophagy repressor.
Successful embryonic development in plants, as in animals, requires a strict coordination of cell... more Successful embryonic development in plants, as in animals, requires a strict coordination of cell proliferation, cell differentiation, and cell-death programs. The role of cell death is especially critical for the establishment of polarity at early stages of plant embryogenesis, when the differentiation of the temporary structure, the suspensor, is followed by its programmed elimination. Here, we review the emerging knowledge of this and other functions of programmed cell death during plant embryogenesis, as revealed by developmental analyses of Arabidopsis embryo-specific mutants and gymnosperm (spruce and pine) model embryonic systems. Cell biological studies in these model systems have helped to identify and order the cellular processes occurring during self-destruction of the embryonic cells. While metazoan embryos can recruit both apoptotic and autophagic cell deaths, the ultimate choice depending on the developmental task and conditions, plant embryos use autophagic cell disas...
Methods in molecular biology (Clifton, N.J.), 2008
Programmed cell death (PCD) is an integral part of embryogenesis. In plant embryos, PCD functions... more Programmed cell death (PCD) is an integral part of embryogenesis. In plant embryos, PCD functions during terminal differentiation and elimination of the temporary organ, suspensor, as well as during establishment of provascular system. Embryo abortion is another example of embryonic PCD activated at pathological situations and in polyembryonic seeds. Recent studies identified the sequence of cytological events leading to cellular self-destruction in plant embryos. As in most if not all the developmental cell deaths in plants, embryonic PCD is hallmarked by autophagic degradation of the cytoplasm and nuclear disassembly that includes breakdown of the nuclear envelope and DNA fragmentation. The optimized setup of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) allows the routine in situ analysis of nuclear DNA fragmentation in plant embryos. This chapter provides step-by-step procedure of how to process embryos for TUNEL and how to combine TUNEL with immu...
Proceedings of The National Academy of Sciences, 2005
Programmed cell death (PCD) is indispensable for eukaryotic development. In animals, PCD is execu... more Programmed cell death (PCD) is indispensable for eukaryotic development. In animals, PCD is executed by the caspase family of cysteine proteases. Plants do not have close homologues of caspases but possess a phylogenetically distant family of cysteine proteases named metacaspases. The cellular function of metacaspases in PCD is unknown. Here we show that during plant embryogenesis, metacaspase mcII-Pa translocates from
Factors regulating dynamics of chromatin structure have direct impact on expression of genetic in... more Factors regulating dynamics of chromatin structure have direct impact on expression of genetic information. Cohesin is a multi-subunit protein complex crucial for pairing sister chromatids during cell division, DNA repair and regulation of gene transcription and silencing. In non-plant species cohesin is loaded on chromatin by the Scc2/Scc4 (NIBPL/MAU2) complex. Here we identify AtSCC4, the Arabidopsis homolog of Scc4, and show that it forms a functional complex with AtSCC2, the homolog of Scc2. We demonstrate that AtSCC2 and AtSCC4 act in the same pathway and that both proteins are indispensable for cell fate determination during early stages of embryo development. Mutant embryos lacking either of these proteins develop only up to the globular stage, and show suspensor over-proliferation phenotype preceded by ectopic auxin maxima distribution. We further establish a new assay to reveal the AtSCC4-dependent dynamics of cohesin loading on chromatin in vivo. Our findings define Scc2/S...
In the animal life cycle, the earliest manifestations of programmed cell death (PCD) can already ... more In the animal life cycle, the earliest manifestations of programmed cell death (PCD) can already be seen during embryogenesis. The aim of this work was to determine if PCD is also involved in the elimination of certain cells during plant embryogenesis. We used a model system of Norway spruce somatic embryogenesis, which represents a multistep developmental pathway with two broad phases. The first phase is represented by proliferating proembryogenic masses (PEMs). The second phase encompasses development of somatic embryos, which arise from PEMs and proceed through the same sequence of stages as described for their zygotic counterparts. Here we demonstrate two successive waves of PCD, which are implicated in the transition from PEMs to somatic embryos and in correct embryonic pattern formation, respectively. The first wave of PCD is responsible for the degradation of PEMs when they give rise to somatic embryos. We show that PCD in PEM cells and embryo formation are closely interlinke...
Vacuolar programmed cell death (PCD) is indispensable for plant development and is accompanied by... more Vacuolar programmed cell death (PCD) is indispensable for plant development and is accompanied by a dramatic growth of lytic vacuoles, which gradually digest cytoplasmic content leading to self-clearance of dying cells. Our recent data demonstrate that vacuolar PCD critically requires autophagy and its upstream regulator, a caspase-fold protease metacaspase. Furthermore, both components lie downstream of the point of no return in the cell-death pathway. Here we consider the possibilities that i) autophagy could have both cytotoxic and cytoprotective roles in the vacuolar PCD, and ii) metacaspase could augment autophagic flux through targeting an as yet unknown autophagy repressor.
Successful embryonic development in plants, as in animals, requires a strict coordination of cell... more Successful embryonic development in plants, as in animals, requires a strict coordination of cell proliferation, cell differentiation, and cell-death programs. The role of cell death is especially critical for the establishment of polarity at early stages of plant embryogenesis, when the differentiation of the temporary structure, the suspensor, is followed by its programmed elimination. Here, we review the emerging knowledge of this and other functions of programmed cell death during plant embryogenesis, as revealed by developmental analyses of Arabidopsis embryo-specific mutants and gymnosperm (spruce and pine) model embryonic systems. Cell biological studies in these model systems have helped to identify and order the cellular processes occurring during self-destruction of the embryonic cells. While metazoan embryos can recruit both apoptotic and autophagic cell deaths, the ultimate choice depending on the developmental task and conditions, plant embryos use autophagic cell disas...
Methods in molecular biology (Clifton, N.J.), 2008
Programmed cell death (PCD) is an integral part of embryogenesis. In plant embryos, PCD functions... more Programmed cell death (PCD) is an integral part of embryogenesis. In plant embryos, PCD functions during terminal differentiation and elimination of the temporary organ, suspensor, as well as during establishment of provascular system. Embryo abortion is another example of embryonic PCD activated at pathological situations and in polyembryonic seeds. Recent studies identified the sequence of cytological events leading to cellular self-destruction in plant embryos. As in most if not all the developmental cell deaths in plants, embryonic PCD is hallmarked by autophagic degradation of the cytoplasm and nuclear disassembly that includes breakdown of the nuclear envelope and DNA fragmentation. The optimized setup of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) allows the routine in situ analysis of nuclear DNA fragmentation in plant embryos. This chapter provides step-by-step procedure of how to process embryos for TUNEL and how to combine TUNEL with immu...
Proceedings of The National Academy of Sciences, 2005
Programmed cell death (PCD) is indispensable for eukaryotic development. In animals, PCD is execu... more Programmed cell death (PCD) is indispensable for eukaryotic development. In animals, PCD is executed by the caspase family of cysteine proteases. Plants do not have close homologues of caspases but possess a phylogenetically distant family of cysteine proteases named metacaspases. The cellular function of metacaspases in PCD is unknown. Here we show that during plant embryogenesis, metacaspase mcII-Pa translocates from
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