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Updated: Jul 13, 2026

Lighting Up the Pathways to Caspase Activation Using Bimolecular Fluorescence Complementation
Published on: March 5, 2018
Proapoptotic histone H1.2 induces CASP-3 and -7 activation by forming a protein complex with CYT c, APAF-1 and CASP-9
Antonio Ruiz-Vela1, Stanley J Korsmeyer
1Howard Hughes Medical Institute, Department of Pathology and Medicine, Harvard Medical School, Boston, MA 02115, USA. aruiz@cnio.es
Abstract:
Cytochrome c (CYT c) is a protein that employs the caspase recruitment domain (CARD)-containing proteins APAF-1 and CASP-9 to activate effectors CASP-3 and -7. By using affinity labeling techniques and mass spectrometry analysis, we show that histone H1.2 is a regulator of caspases upon UV irradiation. We demonstrated that histone H1.2 forms a protein complex with APAF-1, CASP-9 and CYT c upon UV irradiation. In cell-free systems, we show that histone H1.2 triggers activation of CASP-3 and -7 via APAF-1 and CASP-9. We therefore conclude that upon DNA damage histone H1.2 acts as a positive regulator of apoptosome formation.
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