Human IP3 receptor triple knockout stem cells remain pluripotent despite altered mitochondrial metabolism

Julius Rönkkö; Yago Rodriguez; Tiina Rasila; Rubén Torregrosa-Muñumer; Jana Pennonen; Jouni Kvist; Emilia Kuuluvainen; Ludo Van Den Bosch; Ville Hietakangas; Geert Bultynck; Henna Tyynismaa; Emil Ylikallio

doi:10.1016/j.ceca.2023.102782

Human IP₃ receptor triple knockout stem cells remain pluripotent despite altered mitochondrial metabolism

Cell Calcium. 2023 Sep:114:102782. doi: 10.1016/j.ceca.2023.102782. Epub 2023 Jul 17.

Affiliations

¹ Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland.
² Molecular and Integrative Bioscience Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, 00790, Finland; Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, 00790, Finland.
³ Department of Neurosciences, Experimental Neurology and Leuven Brain Institute, KU Leuven - University of Leuven, 3000, Leuven, Belgium; VIB Center for Brain & Disease Research, Laboratory of Neurobiology, 3000, Leuven, Belgium.
⁴ KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine & Leuven Kanker Instituut, Leuven, 3000, Belgium.
⁵ Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, 00290, Finland; Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, 00290, Finland. Electronic address: emil.ylikallio@helsinki.fi.

PMID: 37481871
DOI: 10.1016/j.ceca.2023.102782

Abstract

Inositol 1,4,5-trisphosphate receptors (IP₃Rs) are ER Ca²⁺-release channels that control a broad set of cellular processes. Animal models lacking IP₃Rs in different combinations display severe developmental phenotypes. Given the importance of IP₃Rs in human diseases, we investigated their role in human induced pluripotent stem cells (hiPSC) by developing single IP₃R and triple IP₃R knockouts (TKO). Genome edited TKO-hiPSC lacking all three IP₃R isoforms, IP₃R1, IP₃R2, IP₃R3, failed to generate Ca²⁺ signals in response to agonists activating GPCRs, but retained stemness and pluripotency. Steady state metabolite profiling and flux analysis of TKO-hiPSC indicated distinct alterations in tricarboxylic acid cycle metabolites consistent with a deficiency in their pyruvate utilization via pyruvate dehydrogenase, shifting towards pyruvate carboxylase pathway. These results demonstrate that IP₃Rs are not essential for hiPSC identity and pluripotency but regulate mitochondrial metabolism. This set of knockout hiPSC is a valuable resource for investigating IP₃Rs in human cell types of interest.

Keywords: Ca(2+) signaling; IP(3)R1; IP(3)R2; IP(3)R3; Induced pluripotent stem cells; Inositol 1,4,5-trisphosphate receptors; Mitochondria; TCA; iPSC.