Apoptotic Release of Histones from Nucleosomes

Abstract

Chromatin structure is influenced by histone modification, and this may help direct chromatin behavior to facilitate transcription, DNA replication, and DNA repair. Chromatin condensation and DNA fragmentation are the classic nuclear features but remain poorly characterized. It is highly probable that nucleosomal structure must be altered to allow these features to become apparent, but data to support this construct are lacking. We report here that in response to apoptotic signals from a death receptor (CD95 and tumor necrosis factor-␣) or mitochondrial (staurosporine) apoptotic stimulus, the core nucleosomal histones H2A, H2B, H3, and H4 become separated from DNA during apoptosis in Jurkat and HeLa cells and are consequently detectable in the cell lysate prepared using a non-ionic detergent. The timing of this histone release from DNA correlates well with the progression of apoptosis. We also show expression of a caspase cleavageresistant form of ICAD (ICAD-DM) in Jurkat and HeLa cells abolished DNA fragmentation and also dramatically reduced histone release in apoptotic cells. However, we demonstrate that apoptotic histone release is not an inevitable consequence of CAD/DFF-40-mediated DNA destruction as DNA fragmentation but not histone release occurs efficiently in tumor necrosis factor-␣-and etoposide-treated NIH3T3 cells. Furthermore, in an in vitro apoptotic assay, incubation of apoptotic Jurkat cellular extract with non-apoptotic Jurkat nuclei led to nuclear DNA fragmentation without obvious histone release. Taken together, these data demonstrate that CAD/DFF-40 functions indirectly in mediating nucleosomal destruction during apoptosis.

An endogenous calcium-dependent, caspase-independent intranuclear degradation pathway in thymocyte nuclei: Antagonism by physiological concentrations of K+ ions

“…Previous studies have shown that histones are released in various apoptotic cells [46,47]. Our findings indicate that 1) histones are also released in isolated nuclei treated with Ca 2+ and 2) the amount of histones released corresponds approximately to the amount of internucleosomal DNA.…”

Histidine-Rich Glycoprotein Binds to DNA and FcγRI and Potentiates the Ingestion of Apoptotic Cells by Macrophages

“…In this disease, defective clearance of apoptotic cells has been considered to play a role in its pathogenesis (49,50). Interestingly, recent studies also indicate that, during apoptosis, histones (H1, H2A, H2B, H3, and H4) are released from chromatin, leading to the formation of naked DNA (51). In this study, we provide evidence that DNA on apoptotic cell surfaces binds HRG and affects HRG-dependent binding and ingestion of apoptotic cells.…”

Induction of histone H1.2 cytosolic release in chronic lymphocytic leukemia cells after genotoxic and non-genotoxic treatment

“…These results support the concept that histone release into the cytoplasm was not merely a consequence of DNA fragmentation, and agree with the fact that apoptosis could be detected in apoptotic cells that did not present DNA frag- © F e r r a t a S t o r t i F o u n d a t i o n mentation. 17 To summarize, histone H1.2 release into the cytoplasm in CLL cells could represent a novel and common step in apoptosis induced by different stimuli. Importantly, this new apoptotic effector is abrogated when using DNA damaging agents in highly deleted 17p13 cases.…”

“…[15][16][17] Konishi et al recently reported new insights into the death signal transmission pathway. 18 They demonstrated the apoptogenic ability of histone H1.2 when this protein translocated from the nucleus into the cytosol after DNA double-strand breaks.…”