The BH4 domain of Bcl-2 orthologues from different classes of vertebrates can act as an evolutionary conserved inhibitor of IP3receptor channels.
Ca2+signalling plays an important role in various physiological processes in vertebrates. In mammals, the highly conserved anti-apoptotic B-cell lymphoma-2 (Bcl-2) protein is an important modulator of the inositol 1,4,5-trisphosphate receptor (IP3R), i.e. the main intracellular Ca2+- release channel located at the endoplasmic reticulum (ER). The Bcl-2 Homology (BH) 4 domain of Bcl-2 (BH4-Bcl-2) is a critical determinant for inhibiting IP3Rs, by directly targeting a region in the modulatory domain of the receptor (domain 3). In this paper, we aimed to track the evolutionary history of IP3R regulation by the BH4 domain of Bcl-2 orthologues from different classes of vertebrates, including Osteichthyes, Amphibia, Reptilia, Aves and Mammalia. The high degree of conservation of the BH4 sequences correlated with the ability of all tested peptides to bind to the domain 3 of mouse IP3R1 in GST-pull downs and their overall ability to inhibit IP3-induced Ca2+release (IICR) in permeabilized cells. Nevertheless, the BH4 domains differed in their potency to suppress IICR. The peptide derived from X. laevis was the least potent inhibitor. We identified a critical residue in BH4-Bcl-2 from H. sapiens, Thr7, which is replaced by Gly7 in X. laevis. Compared to the wild type X. laevis BH4-Bcl-2, a "humanized" version of the peptide (BH4-Bcl-2 Gly7Thr), displayed increased IP3R-inhibitory properties. Despite the differences in the inhibitory efficiency, our data indicate that the BH4 domain of Bcl-2 orthologues from different classes of vertebrates can act as a binding partner and inhibitor of IP3R channels.
KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and, Herestraat 49, BE-3000, Leuven, Belgium.
Hristina
H
Ivanova
KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and, Herestraat 49, BE-3000, Leuven, Belgium.
Tomas
T
Luyten
Ghent University, Physiology Group, Department of Basic Medical Sciences, BE-9000, Ghent, Belgium.
Elke
E
Decrock
KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and, Herestraat 49, BE-3000, Leuven, Belgium.
Tim
T
Vervliet
Ghent University, Physiology Group, Department of Basic Medical Sciences, BE-9000, Ghent, Belgium.
Luc
L
Leybaert
KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and, Herestraat 49, BE-3000, Leuven, Belgium; KU Leuven, Leuven Cancer Institute (LKI), BE-3000, Leuven, Belgium.
Jan B
JB
Parys
KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine and, Herestraat 49, BE-3000, Leuven, Belgium; KU Leuven, Leuven Cancer Institute (LKI), BE-3000, Leuven, Belgium. Electronic address: geert.bultynck@kuleuven.be.
Geert
G
Bultynck
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D015186:Hominidae; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051379:Mice; D000072417:Protein Domains; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D014982:Xenopus laevis
D053496:Inositol 1,4,5-Trisphosphate Receptors; D019253:Proto-Oncogene Proteins c-bcl-2; D002118:Calcium
BH4 domain; Bcl-2 orthologues; Calcium signalling; Evolution; IP(3) receptor