1,721,006 research outputs found
Dynamic relocation of nuclear proteins during the execution phase of apoptosis.
No full textIn the apoptotic program of controlled cell dismantling, the most characteristic nuclear changes involve chromatin, which condenses and often collapses against the nuclear envelope in the form of crescents. A severe reorganization also occurs in ribonucleoprotein (RNP)-containing structures which are involved in the synthesis and processing of transcripts: already during early apoptosis, the nucleoplasmic RNPs (namely, perichromatin fibrils, perichromatin granules, and interchromatin granules) coalesce in the interchromatin space where they associate with segregated nucleolar components, to ectopically form fibro-granular heterogeneous clusters. This was found to occur in cell systems in vivo and in cultured cell lines, after different apoptogenic stimuli. These RNP aggregates we have called heterogeneous ectopic RNP-derived structures (HERDS) move from the nucleus to the cytoplasm, and may be found in apoptotic bodies, in late apoptosis. Immunolabeling experiments demonstrated that several other proteins which are normally located inside the nucleus also move into the cytoplasm, during apoptosis, independently from HERDS. Apoptotic cells have been suggested to be a powerful source of nuclear auto-antigens, which are produced by the partial proteolytic or nucleolytic cleavage of a wide variety of nuclear substrates. In the presence of defective phagocytosis (or when massive apoptosis overwhelms the clearance capability of the tissue scavenger cells), the disposal of apoptotic cells becomes insufficient and unphagocytosed late apoptotic cells may accumulate in the tissue where they may be engulfed by antigen-presenting cells (such as dendritic cells); an autoimmune response may thus be elicited, by which apoptosis-derived auto-antigens are recognized and presented to the immune system
Two-color fluorescence detection of Poly(ADP-Ribose) Polymerase-1 (PARP-1) cleavage and DNA strand breaks in etoposide-induced apoptotic cells.
No full textNucleolus disassembly in mitosis and apoptosis: dynamic redistribution of phosphorylated-c-Myc, fibrillarin and Ki-67
No full textApoptosis without DNA fragmentation in HeLa cells after photosensitization with Rose Bengal acetate: involvement of mitochondria.
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Evidence of poly (ADP-ribosylation) in the cockroach Periplaneta americana.
No full textPoly(ADP-ribosylation) is a post-translational modification of nuclear proteins typical of most eukaryotic cells. This process
participates in DNA replication and repakandisnlainly regulated by two enzymes, poly(ADP-ribose) polymerase, which is responsible
for the synthesis of polymers of ADP-ribose, and poly(ADP-ribose) glycohydrolase, which perfonns polymer degradation. The aim 'of this work was to investigate in the cockroach Periplaneta americana L. (Blattaria: Blattidae) the behaviour of poly(ADPribosylation). In particular, we addressed: (i) the possible modulation of poly(ADP-ribosylation) during the embryonic development; (ii) the expression of poly(ADP-ribose) polymerase and glycobydrolase in dilierent tissues; and (iii) the role of poly(ADPribosylation) during spennatogenesis. In this work we demonstrated that: (i) as revealed, by specific biochemical assays, active poly(ADP-ribose) polymerase and glycohydrolase are present exclusively in P. americana embryos at early stages of development; (ii) an activity carrying out poly(ADP-ribose) synthesis was fouod in extracts from testes; and (iii) the synthesis of poly(ADPribose) occurs preferentia1ly in differentiating spermatids/spennatozoa. CoHectively, oUI results indicate that the poly(ADP-ribosylation) process in P. americana, which is a hemimetabolous insect, displays catalytical and structural features similar to those described in the holometabolous insects and in 'mammalian cells. Furthermore,
this process appears to be modulatedduring embryonic development and spermatogenesis
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