Hematological changes induced by various stress stimuli are accompanied by replacement of the primary acetylcholinesterase (AChE) 3′ splice variant acetylcholinesterase-S (AChE-S) with the myelopoietic acetylcholinesterase-R (AChE-R) variant. To search for putative acetylcholinesterase-S interactions with hematopoietic pathways, we employed a yeast two-hybrid screen. The transcriptional co-repressor C-terminal binding protein (CtBP) was identified as a protein partner of the AChE-S C terminus. In erythroleukemic K562 cells, AChE-S displayed nuclear colocalization and physical interaction with CtBP. Furthermore, co-transfected AChE-S reduced the co-repressive effect of CtBP over the hematopoietic transcription factor, Ikaros. In transgenic mice, overexpressed human (h) AChE-S mRNA induced selective bone marrow upregulation of Ikaros while suppressing FOG, another transcriptional partner of CtBP. Transgenic bone marrow cells showed a correspondingly elevated potential for producing progenitor colonies, compared with controls, while peripheral blood showed increased erythrocyte counts as opposed to reduced platelets, granulocytes and T lymphocytes. AChE's 3′ alternative splicing, and the corresponding changes in AChE-S/ CtBP interactions, thus emerge as being actively involved in controlling hematopoiesis and the potential for modulating immune functions, supporting reports on malfunctioning immune reactions under impaired splice site selection.
Bibliographical noteFunding Information:
This work was supported by grants from the Bat Sheva de Rothschild Career Development Award, the Israel Ministry of Health (to CP), United States–Israel Binational Science Foundation (BSF no. 2003028-01 to CP and HS), the Israeli Ministry of Science Grant (to HS and CP), the EU’s Alternative Splicing Network of Excellence (no. 518238) and the EU’s STREP (LSHG-CT no. 2006-037277) and the Israel/Germany Biodisc Program (to HS). We are grateful to Dr M Crossley (Sydney, Australia) for Ikaros and mCtBP vectors, to Dr R Goodman (Portland, OR) for the hCtBP1 vector and to K Ofek and D Toiber (Jerusalem) for assistance in experiments. This work was done at The Hebrew University of Jerusalem and the Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.