bims-mireme 2021-09-26 papers

bims-mireme

Biomed News

on Mitochondria in regenerative medicine

Issue of 2021–09–26
seven papers selected by
Brian Spurlock, The University of North Carolina at Chapel Hill

LIN28A enhances regenerative capacity of human somatic tissue stem cells via metabolic and mitochondrial reprogramming.
An intermediate state in trans-differentiation with proliferation, metabolic, and epigenetic switching.
Fine-tuned repression of Drp1 driven mitochondrial fission primes a 'stem/progenitor-like state' to support neoplastic transformation.
Heritable shifts in redox metabolites during mitochondrial quiescence reprogramme progeny metabolism.
Metformin enhances the osteogenesis and angiogenesis of human umbilical cord mesenchymal stem cells for tissue regeneration engineering.
iPSC culture expansion selects against putatively actionable mutations in the mitochondrial genome.
Untargeted metabolomics in primary murine bone marrow stromal cells reveals distinct profile throughout osteoblast differentiation.

Cell Death Differ. 2021 Sep 23.

LIN28A enhances regenerative capacity of human somatic tissue stem cells via metabolic and mitochondrial reprogramming.

Kelvin Pieknell, Yanuar Alan Sulistio, Noviana Wulansari, Wahyu Handoko Wibowo Darsono, Mi-Yoon Chang, Ji-Yun Ko, Jong Wook Chang, Min-Jeong Kim, Man Ryul Lee, Sang A Lee, Hyunbeom Lee, Gakyung Lee, Byung Hwa Jung, Hyunbum Park, Geun-Ho Kim, Doory Kim, Gayoung Cho, Chun-Hyung Kim, Dat Da Ly, Kyu-Sang Park, Sang-Hun Lee.

Developing methods to improve the regenerative capacity of somatic stem cells (SSCs) is a major challenge in regenerative medicine. Here, we propose the forced expression of LIN28A as a method to modulate cellular metabolism, which in turn enhances self-renewal, differentiation capacities, and engraftment after transplantation of various human SSCs. Mechanistically, in undifferentiated/proliferating SSCs, LIN28A induced metabolic reprogramming from oxidative phosphorylation (OxPhos) to glycolysis by activating PDK1-mediated glycolysis-TCA/OxPhos uncoupling. Mitochondria were also reprogrammed into healthy/fused mitochondria with improved functional capacity. The reprogramming allows SSCs to undergo cell proliferation more extensively with low levels of oxidative and mitochondrial stress. When the PDK1-mediated uncoupling was untethered upon differentiation, LIN28A-SSCs differentiated more efficiently with an increase of OxPhos by utilizing the reprogrammed mitochondria. This study provides mechanistic and practical approaches of utilizing LIN28A and metabolic reprogramming in order to improve SSCs utility in regenerative medicine.

DOI: https://doi.org/10.1038/s41418-021-00873-1
iScience. 2021 Sep 24. 24(9): 103057

An intermediate state in trans-differentiation with proliferation, metabolic, and epigenetic switching.

Zhikai Ye, Wenbo Li, Zhenlong Jiang, Erkang Wang, Jin Wang.

  Although TGF-β signaling can effectively activate fibroblasts to transform to myofibroblasts, the underlying mechanisms involved in the cell fate switching for trans-differentiation have not been fully elucidated. In this study, we found the evidence of an intermediate state in the process of trans-differentiation. In the early stage of trans-differentiation, cells enter the intermediate state first with multiple characteristics such as accelerating cell cycle, metabolic switching, enhanced anti-apoptotic ability, and pluripotency, which is very similar to the early stage of reprogramming. As the trans-differentiation continues, these characteristics get switched. Therefore, trans-differentiation appears to require the switching of cell proliferation ability, metabolic pathway, and "stemness" to complete the process. In this study, we can conclude that an intermediate state may be necessary with high pluripotency in trans-differentiation from fibroblasts to myofibroblasts. Only after passing the intermediate state, the trans-differentiation is finally completed and will not easily return to the original state.

Keywords:  biophysics; cell biology; genetics

DOI:  https://doi.org/10.1016/j.isci.2021.103057
Elife. 2021 Sep 21. pii: e68394. [Epub ahead of print]10

Fine-tuned repression of Drp1 driven mitochondrial fission primes a 'stem/progenitor-like state' to support neoplastic transformation.

Brian Spurlock, Danitra Parker, Malay Kumar Basu, Anita Hjelmeland, Sajina Gc, Shanrun Liu, Gene P Siegal, Alan Gunter, Aida Moran, Kasturi Mitra.

  Gene knockout of the master regulator of mitochondrial fission, Drp1, prevents neoplastic transformation. Also, mitochondrial fission and its opposing process of mitochondrial fusion are emerging as crucial regulators of stemness. Intriguingly, stem/progenitor cells maintaining repressed mitochondrial fission are primed for self-renewal and proliferation. Using our newly derived carcinogen transformed human cell model we demonstrate that fine-tuned Drp1 repression primes a slow cycling 'stem/progenitor-like state', which is characterized by small networks of fused mitochondria and a gene-expression profile with elevated functional stem/progenitor markers (Krt15, Sox2 etc) and their regulators (Cyclin E). Fine tuning Drp1 protein by reducing its activating phosphorylation sustains the neoplastic stem cell markers. Whereas, fine-tuned reduction of Drp1 protein maintains the characteristic mitochondrial shape and gene-expression of the primed 'stem/progenitor-like state' to accelerate neoplastic transformation, and more complete reduction of Drp1 protein prevents it. Therefore, our data highlights a 'goldilocks'; level of Drp1 repression supporting stem/progenitor state dependent neoplastic transformation.

Keywords:  cancer biology; cell biology; mouse

DOI:  https://doi.org/10.7554/eLife.68394
Nat Metab. 2021 Sep;3(9): 1259-1274

Heritable shifts in redox metabolites during mitochondrial quiescence reprogramme progeny metabolism.

Helin Hocaoglu, Lei Wang, Mengye Yang, Sibiao Yue, Matthew Sieber.

Changes in maternal diet and metabolic defects in mothers can profoundly affect health and disease in their progeny. However, the biochemical mechanisms that induce the initial reprogramming events at the cellular level have remained largely unknown owing to limitations in obtaining pure populations of quiescent oocytes. Here, we show that the precocious onset of mitochondrial respiratory quiescence causes a reprogramming of progeny metabolic state. The premature onset of mitochondrial respiratory quiescence drives the lowering of Drosophila oocyte NAD+ levels. NAD+ depletion in the oocyte leads to reduced methionine cycle production of the methyl donor S-adenosylmethionine in embryos and lower levels of histone H3 lysine 27 trimethylation, resulting in enhanced intestinal lipid metabolism in progeny. In addition, we show that triggering cellular quiescence in mammalian cells and chemotherapy-resistant human cancer cell models induces cellular reprogramming events identical to those seen in Drosophila, suggesting a conserved metabolic mechanism in systems reliant on quiescent cells.

DOI: https://doi.org/10.1038/s42255-021-00450-3
Int J Biochem Cell Biol. 2021 Sep 19. pii: S1357-2725(21)00167-9. [Epub ahead of print] 106086

Metformin enhances the osteogenesis and angiogenesis of human umbilical cord mesenchymal stem cells for tissue regeneration engineering.

Tong Lei, Shiwen Deng, Peng Chen, Zhuangzhuang Xiao, Shanglin Cai, Zhongci Hang, Yanjie Yang, Xiaoshuang Zhang, Quanhai Li, Hongwu Du.

  Human umbilical cord mesenchymal stem cells (hUC-MSCs) are a potential clinical material in regenerative medicine applications. Metformin has shown safety and effectiveness as a clinical drug. However, the effect of metformin as a treatment on hUC-MSCs is unclear. Our research aimed to explore the effects of metformin on the osteogenesis, adipogenesis and angiogenesis of hUC-MSCs, and attempted to explain the molecular fluctuations of metformin through the mapping of protein profiles. Proliferation assay, osteogenic and adipogenic differentiation induction, cell cycle, flow cytometry, quantitative proteomics techniques and bioinformatics analysis were used to detect the influences of metformin treatment on hUC-MSCs. Our results demonstrated that low concentrations of metformin promoted the proliferation of hUC-MSCs, but high concentrations of metformin inhibited it. Metformin exhibited promotion of osteogenesis but inhibition of adipogenesis. Metformin treated hUC-MSCs up-regulated the expression of osteogenic marker ALP, OCN and RUNX2, but down-regulated the expression of adipogenic markers PPARγ and LPL. Proteomics analysis found that up-regulation of differentially expressed proteins in metformin treatment group involved the biological process of cell migration in Gene Ontology analysis. Metformin enhanced cell migration of HUVEC in a co-culture system, and hUC-MSCs treated with metformin exhibited stronger angiogenesis in vitro and in vivo compared to the hUC-MSCs group. The results of RT-qPCR revealed that the SCF and VEGFR2 were raised in metformin treatment. This study can promote the application of hUC-MSCs treated with metformin to tissue engineering for vascular reconstruction and angiogenesis.

Keywords:  Angiogenesis; Metformin; Osteogenesis; Proteomics; hUC-MSCs

DOI:  https://doi.org/10.1016/j.biocel.2021.106086
Stem Cell Reports. 2021 Sep 14. pii: S2213-6711(21)00434-3. [Epub ahead of print]

iPSC culture expansion selects against putatively actionable mutations in the mitochondrial genome.

Maike Kosanke, Colin Davenport, Monika Szepes, Lutz Wiehlmann, Tim Kohrn, Marie Dorda, Jonas Gruber, Kaja Menge, Maike Sievert, Anna Melchert, Ina Gruh, Gudrun Göhring, Ulrich Martin.

  Therapeutic application of induced pluripotent stem cell (iPSC) derivatives requires comprehensive assessment of the integrity of their nuclear and mitochondrial DNA (mtDNA) to exclude oncogenic potential and functional deficits. It is unknown, to which extent mtDNA variants originate from their parental cells or from de novo mutagenesis, and whether dynamics in heteroplasmy levels are caused by inter- and intracellular selection or genetic drift. Sequencing of mtDNA of 26 iPSC clones did not reveal evidence for de novo mutagenesis, or for any selection processes during reprogramming or differentiation. Culture expansion, however, selected against putatively actionable mtDNA mutations. Altogether, our findings point toward a scenario in which intracellular selection of mtDNA variants during culture expansion shapes the mutational landscape of the mitochondrial genome. Our results suggest that intercellular selection and genetic drift exert minor impact and that the bottleneck effect in context of the mtDNA genetic pool might have been overestimated.

Keywords:  genomic integrity; induced pluripotent stem cells; mitochondrial genome; prolonged expansion culture; reprogramming; selection; small-scale mutations

DOI:  https://doi.org/10.1016/j.stemcr.2021.08.016
Metabolomics. 2021 Sep 18. 17(10): 86

Untargeted metabolomics in primary murine bone marrow stromal cells reveals distinct profile throughout osteoblast differentiation.

Biswapriya B Misra, Shobana Jayapalan, Alison K Richards, Ron C M Helderman, Elizabeth Rendina-Ruedy.

   INTRODUCTION: Skeletal homeostasis is an exquisitely regulated process most directly influenced by bone resorbing osteoclasts, bone forming osteoblasts, and the mechano-sensing osteocytes. These cells work together to constantly remodel bone as a mechanism to prevent from skeletal fragility. As such, when an individual experiences a disconnect in these tightly coupled processes, fracture incidence increases, such as during ageing, gonadal hormone deficiency, weightlessness, and diabetes. While therapeutic options have significantly aided in the treatment of low bone mineral density (BMD) or osteoporosis, limited options remain for anabolic or bone forming agents. Therefore, it is of interest to continue to understand how osteoblasts regulate their metabolism to support the energy expensive process of bone formation.
OBJECTIVE: The current project sought to rigorously characterize the distinct metabolic processes and intracellular metabolite profiles in stromal cells throughout osteoblast differentiation using untargeted metabolomics.
METHODS: Primary, murine bone marrow stromal cells (BMSCs) were characterized throughout osteoblast differentiation using standard staining protocols, Seahorse XFe metabolic flux analyses, and untargeted metabolomics.
RESULTS: We demonstrate here that the metabolic footprint of stromal cells undergoing osteoblast differentiation are distinct, and while oxidative phosphorylation drives adenosine triphosphate (ATP) generation early in the differentiation process, mature osteoblasts depend on glycolysis. Importantly, the intracellular metabolite profile supports these findings while also suggesting additional pathways critical for proper osteoblast function.
CONCLUSION: These data are the first of their kind to characterize these metabolites in conjunction with the bioenergetic profile in primary, murine stromal cells throughout osteoblast differentiation and provide provocative targets for future investigation.

Keywords:  ATP; Bioenergetics; Bone; LC–MS/MS; Metabolism; Metabolomics

DOI:  https://doi.org/10.1007/s11306-021-01829-9