Biology subjects

Oshima, S.

Publications and source records attributed to Oshima, S..

4 recordsLinked to original sources

bioRxiv2024

Atlas of Cynomolgus Macaque Hematopoiesis

Self-renewal and differentiation are inherent properties of hematopoietic stem cells (HSCs) that are necessary to support hematopoiesis; however, the underlying mechanisms, especially in human, remain unclear. Here, using the cynomolgus macaque as a surrogate model, we develop a new gating strategy to isolate with high purity transplantable cynomolgus HSCs and generated a single-cell transcriptomic map of cynomolgus HSCs and progenitor cells -- that covering gestational periods previously not analyzed in human. We show that hematopoietic cells from the late-1st to early-3rd trimester fetal liver and late-2nd trimester and thereafter bone marrow have repopulating potential, closely mimicking humans. Unexpectedly however, we found unlike in human, cynomolgus HSCs express CD38 but not CD33, indicating that these cellular counterparts are molecularly distinct. Our transcriptomic analysis reveals the presence of a direct differentiation pathway from HSCs to megakaryocyte lineages, lineage-primed multipotent progenitors and also identified putative HSC surface markers. Taken together, our comprehensive dataset highlights not only the utility of cynomolgus monkeys as model systems to study hematopoiesis but also their potential for translational applications.

cell biology↗

bioRxiv2023

Homologous recombination contributes to the repair of acetaldehyde-induced DNA damages.

Acetaldehyde, a chemical that can cause DNA damage and contribute to cancer, is prevalently present in our environment, e.g., in alcohol, tobacco, and food. Although aldehyde potentially promotes crosslinking reaction among biological substances including DNA, RNA, and proteins, it remains unclear what types of DNA damage are caused by acetaldehyde and how they are repaired. In this study, we examined acetaldehyde sensitivity of DNA damage-deficient cells established from human TK6 cell line. Among the mutants, mismatch repair mutants did not show a hypersensitivity to acetaldehyde, while cells deficient in base and nucleotide excision repair pathways increased its sensitivity. We found a delayed repair and hypersensitivity in homologous recombination (HR)-deficient cells but not in non-homologous end joining-deficient cells after acetaldehyde treatment. By analyzing the formation of acetaldehyde-induced RAD51 foci, which represent HR intermediates, HR-deficient cells, but not NHEJ, exhibits delayed repair of acetaldehyde-induced DNA damages, compared with wild-type. These results suggest that acetaldehyde causes complex DNA damages that requires various types of repair pathways. Interestingly, mutants deficient in TDP1 and TDP2, which are involved in the removal of protein adducts from DNA ends, exhibited hypersensitivity to acetaldehyde. the acetaldehyde sensitivity of the TDP1-/-/RAD54-/- double mutant was similar to that of each single mutant. This epistatic relationship between TDP1 and RAD54 suggests that that the removal of protein-DNA adducts generated by acetaldehyde needs to be removed for efficient repair by HR. Our study would help understand the molecular mechanism of genotoxic and mutagenic effects of acetaldehyde.

molecular biology↗

bioRxiv2022

SARS-CoV-2 ORF8 is a viral cytokine regulating immune responses

Many patients with severe COVID-19 suffer from pneumonia, and thus elucidation of the mechanisms underlying the development of such severe pneumonia is important. The ORF8 protein is a secreted protein of SARS-CoV-2, whose in vivo function is not well understood. Here, we analyzed the function of ORF8 protein by generating ORF8-knockout SARS-CoV-2. We found that the lung inflammation observed in wild-type SARS-CoV-2-infected hamsters was decreased in ORF8-knockout SARS-CoV-2-infected hamsters. Administration of recombinant ORF8 protein to hamsters also induced lymphocyte infiltration into the lungs. Similar pro-inflammatory cytokine production was observed in primary human monocytes treated with recombinant ORF8 protein. Furthermore, we demonstrate that the serum ORF8 protein levels are correlated well with clinical markers of inflammation. These results demonstrated that the ORF8 protein is a viral cytokine of SARS-CoV-2 involved in the in the immune dysregulation observed in COVID-19 patients, and that the ORF8 protein could be a novel therapeutic target in severe COVID-19 patients.

microbiology↗

bioRxiv2022

Indirect CRISPR screening with photoconversion revealed key factors of drug resistance with cell-cell interactions

Comprehensive screenings to clarify indirect cell-cell interactions, such as those in the tumor microenvironment, especially comprehensive assessments of supporting cells effects, are challenging. Therefore, in this study, indirect CRISPR screening for drug resistance with cell-cell interactions was invented. The photoconvertible fluorescent protein Dendra2 was inducted to determine the drug resistance responsible factors of supporting cells with CRISPR screenings. Random mutated supporting cells co-cultured with leukemic cells induced drug resistance with cell- cell interactions. Supporting cells responsible for drug resistance were isolated with green-to-red photoconversion, and 39 candidate genes were identified. Knocking out C9orf89, MAGI2, MLPH, or RHBDD2 in supporting cells reduced the ratio of apoptosis of cancer cells. In addition, the low expression of RHBDD2 in supporting cells, specifically fibroblasts, of clinical pancreatic cancer showed a shortened prognosis, and a negative correlation with CXCL12 was observed. Indirect CRISPR screening was established to isolate the responsible elements of cell-cell interactions. This screening method could reveal new mechanisms in all kinds of cell-cell interactions by revealing live phenotype-inducible cells, and it could be a new platform for discovering new targets of drugs for conventional chemotherapies.

cancer biology↗