The BH4 domain of Bcl-2 inhibits ER calcium release and apoptosis by binding the regulatory and coupling domain of the IP3 receptor

Rong, Yi-Ping; Bultynck, Geert; Aromolaran, Ademuyiwa S.; Zhong, Fei; Parys, Jan B.; De Smedt, Humbert; Mignery, Gregory A.; Roderick, H Llewelyn; Bootman, Martin and Distelhorst, Clark W. (2009). The BH4 domain of Bcl-2 inhibits ER calcium release and apoptosis by binding the regulatory and coupling domain of the IP3 receptor. Proceedings of the National Academy of Sciences of the United States of America, 106(34) pp. 14397–14402.

DOI: https://doi.org/10.1073/pnas.0907555106

Abstract

Although the presence of a BH4 domain distinguishes the antiapoptotic protein Bcl-2 from its proapoptotic relatives, little is known about its function. BH4 deletion converts Bcl-2 into a proapoptotic protein, whereas a TAT-BH4 fusion peptide inhibits apoptosis and improves survival in models of disease due to accelerated apoptosis. Thus, the BH4 domain has antiapoptotic activity independent of full-length Bcl-2. Here we report that the BH4 domain mediates interaction of Bcl-2 with the inositol 1,4,5-trisphosphate (IP3) receptor, an IP3-gated Ca(2+) channel on the endoplasmic reticulum (ER). BH4 peptide binds to the regulatory and coupling domain of the IP3 receptor and inhibits IP3-dependent channel opening, Ca(2+) release from the ER, and Ca(2+)-mediated apoptosis. A peptide inhibitor of Bcl-2-IP3 receptor interaction prevents these BH4-mediated effects. By inhibiting proapoptotic Ca(2+) signals at their point of origin, the Bcl-2 BH4 domain has the facility to block diverse pathways through which Ca(2+) induces apoptosis.

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