Renkema, H. | Search bioRxiv

bioRxiv2024

Restoring oxidative phosphorylation enhances osteogenesis in mitochondrial DNA translation defective human bone marrow stromal cells

Bone formation is critical to maintain bone integrity. Here, we studied the importance of intact energy metabolism for bone formation in humans. The skeletal impact of impaired oxidative phosphorylation (OXPHOS) was investigated in adult individuals with genetically defective mitochondrial DNA translation (m.3243A>G). Although impaired mitochondrial ATP production in m.3243A>G human bone marrow stromal cells (hBMSC) was compensated by increased glycolytic ATP production (unchanged net ATP production), both in vitro osteoblast differentiation and in vivo ectopic bone formation were decreased. The impaired OXPHOS was associated with mitochondrial stress and disruption of the pro-osteogenic transcriptional program characteristic of hBMSC. Supporting OXPHOS pharmacologically in hBMSC restored mitochondrial ATP production, their transcriptional program and metabolism, leading to upregulation of osteogenic genes and restoration of bone formation capacity. These findings demonstrate a mitochondrial regulation mechanism of the osteogenic capacity of hBMSCs and identify OXPHOS as a potential target for increasing bone formation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/629993v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@fca817org.highwire.dtl.DTLVardef@17fb2d3org.highwire.dtl.DTLVardef@b5667forg.highwire.dtl.DTLVardef@15c35db_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2020

Sonlicromanol improves neuronal network dysfunction and transcriptome changes linked to m.3243A > G heteroplasmy in iPSC-derived neurons

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) is often caused by an adenine to guanine mutation at m.3243 (m.3243A>G) of the MT-TL1 gene (tRNAleu(UUR)). To understand how this mutation affects the nervous system, we differentiated human induced-pluripotent stem cells (iPSCs) into excitatory neurons with normal (low heteroplasmy) and impaired (high heteroplasmy) mitochondrial function from MELAS patients with the m.3243A>G mutation. We combined micro-electrode array (MEA) measurements with RNA sequencing (MEA-seq) and found that the m.3243A>G mutation affects expression of genes involved in mitochondrial respiration- and presynaptic function, as well as non-cell autonomous processes in co-cultured astrocytes. Finally, we show that the clinical II stage drug sonlicromanol (KH176) improved neuronal network activity in a patient-specific manner when treatment is initiated early in development. This was intricately linked with changes in the neural transcriptome. Overall, MEA-seq is a powerful approach to identify mechanisms underlying the m.3243A>G mutation and to study the effect of pharmacological interventions in iPSC-derived neurons. Highlights- High m.3243A>G heteroplasmy leads to lower neuronal network activity and synchronicity - High heteroplasmy affects expression of genes involved in mitochondrial ATP production and the synaptic function / the presynaptic vesicle cycle - High neuronal heteroplasmy non cell autonomously affects gene expression in healthy co-cultured astrocytes - Sonlicromanol partially rescues neuronal network activity and transcriptome changes induced by high heteroplasmy eTOC BlurbUsing human inducible pluripotent stem cell-derived neurons with high levels of m.3243A>G heteroplasmy, Klein Gunnewiek et al. show transcriptome changes underlying the functional neuronal network phenotype, and how sonlicromanol can partially improve both this neuronal network phenotype, and the transcriptome changes, in a patient-specific manner.

neuroscience↗