Changes in mitochondrial thymidine metabolism and mtDNA copy number during induced pluripotency

Abstract Somatic cell reprogramming into human induced pluripotent stem cells entails significant intracellular changes, including modifications in mitochondrial metabolism and a decrease in mitochondrial DNA copy number. However, the mechanisms underlying this decrease in mitochondrial DNA copy num...

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Main Authors: Hyun Kyu Kim, Yena Song, Minji Kye, Byeongho Yu, Hyung Kyu Choi, Sung-Hwan Moon, Man Ryul Lee
Format: Article
Language:English
Published: Nature Publishing Group 2025-06-01
Series:Experimental and Molecular Medicine
Online Access:https://doi.org/10.1038/s12276-025-01476-3
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author Hyun Kyu Kim
Yena Song
Minji Kye
Byeongho Yu
Hyung Kyu Choi
Sung-Hwan Moon
Man Ryul Lee
author_facet Hyun Kyu Kim
Yena Song
Minji Kye
Byeongho Yu
Hyung Kyu Choi
Sung-Hwan Moon
Man Ryul Lee
author_sort Hyun Kyu Kim
collection DOAJ
description Abstract Somatic cell reprogramming into human induced pluripotent stem cells entails significant intracellular changes, including modifications in mitochondrial metabolism and a decrease in mitochondrial DNA copy number. However, the mechanisms underlying this decrease in mitochondrial DNA copy number during reprogramming remain unclear. Here we aimed to elucidate these underlying mechanisms. Through a meta-analysis of several RNA sequencing datasets, we identified genes responsible for the decrease in mitochondrial DNA. We investigated the functions of these identified genes and assessed their regulatory mechanisms. In particular, the expression of the thymidine kinase 2 gene (TK2), located in the mitochondria and required for mitochondrial DNA synthesis, is decreased in human pluripotent stem cells as compared with its expression in somatic cells. TK2 was significantly downregulated during reprogramming and markedly upregulated during differentiation. Collectively, this decrease in TK2 levels induces a decrease in mitochondrial DNA copy number and contributes to shaping the metabolic characteristics of human pluripotent stem cells. However, contrary to our expectations, treatment with a TK2 inhibitor impaired somatic cell reprogramming. These results suggest that decreased TK2 expression may result from metabolic conversion during somatic cell reprogramming.
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series Experimental and Molecular Medicine
spelling doaj-art-e5e23873d6574d35b183e7ad2bd4aa722025-08-20T04:01:47ZengNature Publishing GroupExperimental and Molecular Medicine2092-64132025-06-015761272128210.1038/s12276-025-01476-3Changes in mitochondrial thymidine metabolism and mtDNA copy number during induced pluripotencyHyun Kyu Kim0Yena Song1Minji Kye2Byeongho Yu3Hyung Kyu Choi4Sung-Hwan Moon5Man Ryul Lee6Soonchunhyang Institute of Medi-bio Science, Soon Chun Hyang UniversitySoonchunhyang Institute of Medi-bio Science, Soon Chun Hyang UniversitySoonchunhyang Institute of Medi-bio Science, Soon Chun Hyang UniversitySoonchunhyang Institute of Medi-bio Science, Soon Chun Hyang UniversityDepartment of Animal Science and Technology, Chung-Ang UniversityDepartment of Animal Science and Technology, Chung-Ang UniversityDepartment of Stem Cell and Regenerative Biotechnology, KU Institute of Science and Technology, The Institute of Advanced Regenerative Science, Konkuk UniversityAbstract Somatic cell reprogramming into human induced pluripotent stem cells entails significant intracellular changes, including modifications in mitochondrial metabolism and a decrease in mitochondrial DNA copy number. However, the mechanisms underlying this decrease in mitochondrial DNA copy number during reprogramming remain unclear. Here we aimed to elucidate these underlying mechanisms. Through a meta-analysis of several RNA sequencing datasets, we identified genes responsible for the decrease in mitochondrial DNA. We investigated the functions of these identified genes and assessed their regulatory mechanisms. In particular, the expression of the thymidine kinase 2 gene (TK2), located in the mitochondria and required for mitochondrial DNA synthesis, is decreased in human pluripotent stem cells as compared with its expression in somatic cells. TK2 was significantly downregulated during reprogramming and markedly upregulated during differentiation. Collectively, this decrease in TK2 levels induces a decrease in mitochondrial DNA copy number and contributes to shaping the metabolic characteristics of human pluripotent stem cells. However, contrary to our expectations, treatment with a TK2 inhibitor impaired somatic cell reprogramming. These results suggest that decreased TK2 expression may result from metabolic conversion during somatic cell reprogramming.https://doi.org/10.1038/s12276-025-01476-3
spellingShingle Hyun Kyu Kim
Yena Song
Minji Kye
Byeongho Yu
Hyung Kyu Choi
Sung-Hwan Moon
Man Ryul Lee
Changes in mitochondrial thymidine metabolism and mtDNA copy number during induced pluripotency
Experimental and Molecular Medicine
title Changes in mitochondrial thymidine metabolism and mtDNA copy number during induced pluripotency
title_full Changes in mitochondrial thymidine metabolism and mtDNA copy number during induced pluripotency
title_fullStr Changes in mitochondrial thymidine metabolism and mtDNA copy number during induced pluripotency
title_full_unstemmed Changes in mitochondrial thymidine metabolism and mtDNA copy number during induced pluripotency
title_short Changes in mitochondrial thymidine metabolism and mtDNA copy number during induced pluripotency
title_sort changes in mitochondrial thymidine metabolism and mtdna copy number during induced pluripotency
url https://doi.org/10.1038/s12276-025-01476-3
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