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Non-apoptotic function of caspases in a cellular model of hydrogen peroxide-associated colitis.

Poehlmann A, Reissig K, Just A, Walluscheck D, Hartig R, Schinlauer A, Lessel W, Guenther T, Silver A, Steinberg P, Roessner A - J. Cell. Mol. Med. (2013)

Bottom Line: Conversely, we found that oxidative stress led to caspase-dependent proteolytic degradation of the DNA-damage checkpoint protein ATM that is upstream of γ-H2AX.As a consequence, undetected DNA-damage and increased proliferation were found in repeatedly H2 O2 -exposed HCEC.Such features have been associated with neoplastic transformation and appear here to be mediated by a non-apoptotic function of caspases.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Otto-von-Guericke University, Magdeburg, Germany. angela.poehlmann@med.ovgu.de

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Non-apoptotic function of caspases through their role in cell cycle regulation. (A) Cell cycle analysis of H2O2-treated HCEC following pre-incubation with the pan-caspase inhibitor Z-VAD-FMK showed more cells in the G1-phase (24 hrs) and fewer cells in the G2/M-phase, but more cells in the G1- and S-phase after 48 hrs. After 72 hrs, an apoptotic cell population (cell debris) increased significantly. The data are representative of three independent experiments. (B) Immunoblot analysis of H2O2-exposed HCEC, pre-treated with the pan-caspase inhibitor Z-VAD-FMK, revealed a caspase-mediated negative regulation of γ-H2AX and a positive regulation of the JNK pathway, including p-JNK and p-c-jun (Ser63/Ser73), after 24 hrs.
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fig03: Non-apoptotic function of caspases through their role in cell cycle regulation. (A) Cell cycle analysis of H2O2-treated HCEC following pre-incubation with the pan-caspase inhibitor Z-VAD-FMK showed more cells in the G1-phase (24 hrs) and fewer cells in the G2/M-phase, but more cells in the G1- and S-phase after 48 hrs. After 72 hrs, an apoptotic cell population (cell debris) increased significantly. The data are representative of three independent experiments. (B) Immunoblot analysis of H2O2-exposed HCEC, pre-treated with the pan-caspase inhibitor Z-VAD-FMK, revealed a caspase-mediated negative regulation of γ-H2AX and a positive regulation of the JNK pathway, including p-JNK and p-c-jun (Ser63/Ser73), after 24 hrs.

Mentions: Cell cycle analysis following caspase inhibition using Z-VAD-FMK showed (i) fewer cells in S- and more cells in the G1-phase after 24 hrs, (ii) fewer cells in G2/M- and more cells in the S-, G1-phase and debris after 48 hrs and (iii) fewer cells in G2/M-phase, but more cell debris after 72 hrs (Fig. 3A, G1: 14.5–21.6% after 24 hrs, 10.2–16.3% after 48 hrs; cell debris: 58.0–67.0% after 72 hrs). Thus, caspases seem to promote progression of cells through the G1- and S-phase by overriding the G1/S- and intra-S checkpoint, respectively. Consequently, caspases support cell survival by halting cells in the G2/M-phase after 72 hrs. Without proteolytic active caspases, a considerably higher percentage of cells underwent apoptosis (Fig. 3A, cell debris: 67.0% instead of 58.0%). It is apparent, therefore, that apoptosis is caspase-independent and that survival is dependent on proteolytic active caspases, generating cleaved caspase fragments (Fig. 2A).


Non-apoptotic function of caspases in a cellular model of hydrogen peroxide-associated colitis.

Poehlmann A, Reissig K, Just A, Walluscheck D, Hartig R, Schinlauer A, Lessel W, Guenther T, Silver A, Steinberg P, Roessner A - J. Cell. Mol. Med. (2013)

Non-apoptotic function of caspases through their role in cell cycle regulation. (A) Cell cycle analysis of H2O2-treated HCEC following pre-incubation with the pan-caspase inhibitor Z-VAD-FMK showed more cells in the G1-phase (24 hrs) and fewer cells in the G2/M-phase, but more cells in the G1- and S-phase after 48 hrs. After 72 hrs, an apoptotic cell population (cell debris) increased significantly. The data are representative of three independent experiments. (B) Immunoblot analysis of H2O2-exposed HCEC, pre-treated with the pan-caspase inhibitor Z-VAD-FMK, revealed a caspase-mediated negative regulation of γ-H2AX and a positive regulation of the JNK pathway, including p-JNK and p-c-jun (Ser63/Ser73), after 24 hrs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3822895&req=5

fig03: Non-apoptotic function of caspases through their role in cell cycle regulation. (A) Cell cycle analysis of H2O2-treated HCEC following pre-incubation with the pan-caspase inhibitor Z-VAD-FMK showed more cells in the G1-phase (24 hrs) and fewer cells in the G2/M-phase, but more cells in the G1- and S-phase after 48 hrs. After 72 hrs, an apoptotic cell population (cell debris) increased significantly. The data are representative of three independent experiments. (B) Immunoblot analysis of H2O2-exposed HCEC, pre-treated with the pan-caspase inhibitor Z-VAD-FMK, revealed a caspase-mediated negative regulation of γ-H2AX and a positive regulation of the JNK pathway, including p-JNK and p-c-jun (Ser63/Ser73), after 24 hrs.
Mentions: Cell cycle analysis following caspase inhibition using Z-VAD-FMK showed (i) fewer cells in S- and more cells in the G1-phase after 24 hrs, (ii) fewer cells in G2/M- and more cells in the S-, G1-phase and debris after 48 hrs and (iii) fewer cells in G2/M-phase, but more cell debris after 72 hrs (Fig. 3A, G1: 14.5–21.6% after 24 hrs, 10.2–16.3% after 48 hrs; cell debris: 58.0–67.0% after 72 hrs). Thus, caspases seem to promote progression of cells through the G1- and S-phase by overriding the G1/S- and intra-S checkpoint, respectively. Consequently, caspases support cell survival by halting cells in the G2/M-phase after 72 hrs. Without proteolytic active caspases, a considerably higher percentage of cells underwent apoptosis (Fig. 3A, cell debris: 67.0% instead of 58.0%). It is apparent, therefore, that apoptosis is caspase-independent and that survival is dependent on proteolytic active caspases, generating cleaved caspase fragments (Fig. 2A).

Bottom Line: Conversely, we found that oxidative stress led to caspase-dependent proteolytic degradation of the DNA-damage checkpoint protein ATM that is upstream of γ-H2AX.As a consequence, undetected DNA-damage and increased proliferation were found in repeatedly H2 O2 -exposed HCEC.Such features have been associated with neoplastic transformation and appear here to be mediated by a non-apoptotic function of caspases.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Otto-von-Guericke University, Magdeburg, Germany. angela.poehlmann@med.ovgu.de

Show MeSH
Related in: MedlinePlus