Toshiro Saito1, Takeshi Uchiumi1, Mikako Yagi1, Rie Amamoto1,2, Daiki Setoyama1, Yuichi Matsushima1, Dongchon Kang1. 1. Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-Ku, Fukuoka 812-8582, Japan. 2. Department of Nutritional Sciences, Faculty of Health and Welfare, Seinan Jo Gakuin University, Kokurakita-Ku, Kitakyushu 803-0835, Japan.
Abstract
AIMS: Mitochondria are important organelles, dedicated to energy production. Mitochondrial p32/C1qbp, which functions as an RNA and protein chaperone, interacts with mitochondrial mRNA and is indispensable for mitochondrial function through its regulation of mitochondrial translation in cultured cell lines. However, the precise role of p32/C1qbp in vivo is poorly understood because of embryonic lethality in the systemic p32-deficient mouse. The goal of this study was to examine the physiological function of mitochondrial p32/C1qbp in the heart. METHODS AND RESULTS: We investigated the role of p32 in regulating cardiac function in mice using a Cre-loxP recombinase technology against p32 with tamoxifen-inducible knockdown or genetic ablation during postnatal periods. Cardiomyocyte-specific deletion of p32 resulted in contractile dysfunction, cardiac dilatation and cardiac fibrosis, compared with hearts of control mice. We also found decreased COX1 expression, decreased rates of oxygen consumption and increased oxidative stress, indicating that these mice had cardiac mitochondrial dysfunction provoked by p32-deficiency at early stage. Next, we investigated lifespan in cardiac-specific p32-deficient mice. The mice died beginning at 12 months and their median lifespan was ∼14 months. Cardiac mitochondria in the p32-deficient mice showed disordered alignment, enlargement and abnormalities in their internal structure by electron microscopy. We observed that, in p32-deficient compared with control myocytes, AMPKɑ was constitutively phosphorylated and 4EBP-1 and ribosomal S6K were less phosphorylated, suggesting impairment of mammalian target of rapamycin signalling. Finally, we found that expression levels of mitokines such as FGF21 and of integrated stress response genes were significantly increased. Metabolic analysis demonstrated that the urea cycle was impaired in the p32-deficient hearts. CONCLUSION: These findings support a key role for mitochondrial p32 protein in cardiac myocytes modulating mitochondrial translation and function, and thereby survival. Published on behalf of the European Society of Cardiology. All rights reserved.
AIMS: Mitochondria are important organelles, dedicated to energy production. Mitochondrial p32/C1qbp, which functions as an RNA and protein chaperone, interacts with mitochondrial mRNA and is indispensable for mitochondrial function through its regulation of mitochondrial translation in cultured cell lines. However, the precise role of p32/C1qbp in vivo is poorly understood because of embryonic lethality in the systemic p32-deficient mouse. The goal of this study was to examine the physiological function of mitochondrial p32/C1qbp in the heart. METHODS AND RESULTS: We investigated the role of p32 in regulating cardiac function in mice using a Cre-loxP recombinase technology against p32 with tamoxifen-inducible knockdown or genetic ablation during postnatal periods. Cardiomyocyte-specific deletion of p32 resulted in contractile dysfunction, cardiac dilatation and cardiac fibrosis, compared with hearts of control mice. We also found decreased COX1 expression, decreased rates of oxygen consumption and increased oxidative stress, indicating that these mice had cardiac mitochondrial dysfunction provoked by p32-deficiency at early stage. Next, we investigated lifespan in cardiac-specific p32-deficient mice. The mice died beginning at 12 months and their median lifespan was ∼14 months. Cardiac mitochondria in the p32-deficient mice showed disordered alignment, enlargement and abnormalities in their internal structure by electron microscopy. We observed that, in p32-deficient compared with control myocytes, AMPKɑ was constitutively phosphorylated and 4EBP-1 and ribosomal S6K were less phosphorylated, suggesting impairment of mammalian target of rapamycin signalling. Finally, we found that expression levels of mitokines such as FGF21 and of integrated stress response genes were significantly increased. Metabolic analysis demonstrated that the urea cycle was impaired in the p32-deficient hearts. CONCLUSION: These findings support a key role for mitochondrial p32 protein in cardiac myocytes modulating mitochondrial translation and function, and thereby survival. Published on behalf of the European Society of Cardiology. All rights reserved.
Authors: Gregory Webster; Meredith Reynolds; Nicoleta C Arva; Lisa M Dellefave-Castillo; Hilary S McElligott; Amber Kofman; Aleksandra Laboski; Defne Magnetta; Alfred L George; Elizabeth M McNally; Megan J Puckelwartz Journal: Am J Med Genet A Date: 2021-05-18 Impact factor: 2.578
Authors: René G Feichtinger; Monika Oláhová; Yoshihito Kishita; Caterina Garone; Laura S Kremer; Mikako Yagi; Takeshi Uchiumi; Alexis A Jourdain; Kyle Thompson; Aaron R D'Souza; Robert Kopajtich; Charlotte L Alston; Johannes Koch; Wolfgang Sperl; Elisa Mastantuono; Tim M Strom; Saskia B Wortmann; Thomas Meitinger; Germaine Pierre; Patrick F Chinnery; Zofia M Chrzanowska-Lightowlers; Robert N Lightowlers; Salvatore DiMauro; Sarah E Calvo; Vamsi K Mootha; Maurizio Moggio; Monica Sciacco; Giacomo P Comi; Dario Ronchi; Kei Murayama; Akira Ohtake; Pedro Rebelo-Guiomar; Masakazu Kohda; Dongchon Kang; Johannes A Mayr; Robert W Taylor; Yasushi Okazaki; Michal Minczuk; Holger Prokisch Journal: Am J Hum Genet Date: 2017-09-21 Impact factor: 11.025