Biology subjects

Miharada, N.

Publications and source records attributed to Miharada, N..

3 recordsLinked to original sources

bioRxiv2022

Inducing synthetic lethality for selective targeting of acute myeloid leukemia cells harboring STAG2 mutations

Targeted therapies exploiting selective vulnerabilities of malignant cells are highly desired for clinical applications. The cohesin protein complex comprises of RAD21, SMC3, SMC1A as well as a fourth subunit that consists of either STAG1 or STAG2 and is essential for proper chromosomal segregation during mitosis. STAG2 loss-of-function mutations are recurrent driver events in acute myeloid leukemia (AML) and appear relatively early during leukemogenesis. Studies in cell lines have shown that STAG2 deficient cells are uniquely vulnerable to STAG1 perturbation, and this vulnerability could thus be exploited to selectively eliminate STAG2 null AML cells. Here we show that partial perturbation of STAG1 is well tolerated by normal human hematopoietic stem cells and does not affect their functionality. By contrast, STAG1 knockdown is lethal to STAG2 null human HSCs by inducing major mitotic defects. Moreover, STAG1 knockdown induced synthetic lethality in primary human AML cells harboring a STAG2 mutation and completely abrogated leukemia progression in xenograft models. Overall, our study provides proof-of-concept demonstration of a synthetic lethal approach to selectively target primary human cancer cells with STAG2 mutations

cancer biology↗

bioRxiv2021

Retinoids rescue ceruloplasmin secretion and alleviate oxidative stress in Wilson's disease-specific hepatocytes

Wilsons disease (WD) is a copper metabolic disorder, which is caused by defective ATP7B function. Here, we have generated induced pluripotent stem cells (iPSCs) from WD patients carrying compound heterozygous mutations on ATP7B. ATP7B loss- and gain-of-functions were further manifested with ATP7B-deficient iPSCs and heterozygously-corrected R778L WD patient-derived iPSCs using CRISPR-Cas9-based gene editing. Transcriptome analysis identified abnormalities of retinoid signaling pathway and lipid metabolism in WD-specific hepatocytes. Although the expression level of ATP7B protein was variable among WD-specific hepatocytes, the expression and secretion of ceruloplasmin (Cp), which is a downstream copper carrier in plasma, were consistently decreased. Cp secretion-based drug screening identified all-trans retinoic acid (ATRA) as promising candidates for rescuing Cp secretion. ATRA also alleviated reactive oxygen species (ROS) production induced by lipid accumulation in WD-specific hepatocytes. Our patient-derived iPSC-based hepatic models provide potential therapeutics for liver steatosis in WD and other fatty liver diseases.

cell biology↗

bioRxiv2021

Genome-wide association study on 13,167 individuals identifies regulators of hematopoietic stem and progenitor cell levels in human blood

Understanding how hematopoietic stem and progenitor cells (HSPCs) are regulated is of central importance for the development of new therapies for blood disorders and stem cell transplantation. To date, HSPC regulation has been extensively studied in vitro and in animal models, but less is known about the mechanisms in vivo in humans. Here, in a genome-wide association study on 13,167 individuals, we identify 9 significant and 2 suggestive DNA sequence variants that influence HSPC (CD34+) levels in human blood. The identified loci associate with blood disorders, harbor known and novel HSPC genes, and affect gene expression in HSPCs. Interestingly, our strongest association maps to the PPM1H gene, encoding an evolutionarily conserved serine/threonine phosphatase never previously implicated in stem cell biology. PPM1H is expressed in HSPCs, and the allele that confers higher blood CD34+ cell levels downregulates PPM1H. By functional fine-mapping, we find that this downregulation is caused by the variant rs772557-A, which abrogates a MYB transcription factor binding site in PPM1H intron 1 that is active in specific HSPC subpopulations, including hematopoietic stem cells, and interacts with the promoter by chromatin looping. Furthermore, rs772557-A selectively increases HSPC subpopulations in which the MYB site is active, and PPM1H shRNA- knockdown increased CD34+ and CD34+90+ cell proportions in umbilical cord blood cultures. Our findings represent the first large-scale association study on a stem cell trait, illuminating HSPC regulation in vivo in humans, and identifying PPM1H as a novel inhibition target that can potentially be utilized clinically to facilitate stem cell harvesting for transplantation.

genomics↗