Biology subjects

Konishi, R.

Publications and source records attributed to Konishi, R..

6 recordsLinked to original sources

bioRxiv2026

Parasitophorous vacuole membranes of Toxoplasma gondii and Plasmodium falciparum lack the lipid asymmetry characteristic of host cell plasma membranes

Apicomplexan parasites, including Toxoplasma gondii and Plasmodium falciparum, reside within a specialized compartment known as the parasitophorous vacuole (PV) during their intracellular life cycle. The PV membrane (PVM), which derives from the host plasma membrane upon invasion, serves as a selective barrier that permits nutrient acquisition while shielding the parasite from host defense mechanisms. Although the protein composition of the PVM has been studied extensively, its lipid organization remains poorly understood. Using the quick-freeze, freeze-fracture replica labeling (QF-FRL) method, we quantitatively analyzed the transbilayer distribution of phosphatidylserine (PtdSer), phosphatidylethanolamine (PtdEtn), and GM3 ganglioside in the PVM of T. gondii and P. falciparum. Unlike host cell plasma membranes, where these lipids exhibit strict asymmetry--PtdSer and PtdEtn confined to the cytoplasmic leaflet and GM3 to the exoplasmic leaflet--we found that all three lipids were symmetrically distributed across both leaflets of the PVM. This striking loss of lipid asymmetry suggests that the PVM undergoes profound remodeling during infection. The presence of PtdSer and PtdEtn in the luminal leaflet may facilitate the binding of perforin-like proteins (PLP1s) during egress. These findings reveal a unique feature of the PVM that redefines our understanding of host-parasite membrane biology.

cell biology↗

bioRxiv2025

Gelsolin Counteracts ER Stress-Driven Inflammatory Circuits in Psoriasis-like Dermatitis

Psoriasis is a chronic inflammatory skin disorder driven by amplified communication between immune cells and keratinocytes. Here, we show that imiquimod (IMQ) triggers organelle stress responses that directly contribute to this pathogenic circuit. In dendritic cells (DCs), IMQ promotes formation of ER-mitochondria contact sites (MAMs), inducing ER stress and activation of the unfolded protein response (UPR). These pathways act independently of, yet converge with, TLR7/MyD88 signaling to enhance IL-23 expression. IMQ also increases cytosolic Ca{superscript 2}+, facilitating NLRP3 inflammasome activation and release of mitochondrial DNA (mtDNA). In parallel, keratinocytes exposed to IMQ activate UPR-dependent genes, including Defb14 (mBD14), a psoriasis-associated antimicrobial peptide. Extracellular mtDNA and mBD14 then cooperatively stimulate plasmacytoid DCs through TLR9, establishing a feed-forward inflammatory loop. We further identify Gelsolin as a direct IMQ-binding protein that mitigates IMQ-induced ER stress; its loss amplifies ER stress, UPR activation, and oxidative stress, and its expression is reduced in human psoriatic lesions. Thus, MAM-UPR signaling links intracellular organelle stress to the intercellular networks that drive psoriatic inflammation, with Gelsolin acting as a critical intrinsic safeguard.

immunology↗

bioRxiv2025

Regulation of macroautophagy and microautophagic lipophagy by phosphatidylserine synthase Cho1 and external ethanolamine

Phospholipids play crucial roles in autophagy; however, the underlying mechanisms remain elusive. We previously found that the phosphatidylserine (PtdSer) transporter Osh5 is critical for autophagosome formation. Therefore, in this study, we aimed to investigate the impact of the knockout of cho1, which encodes PtdSer synthase, on autophagy. Green fluorescent protein-autophagy-related gene 8 (GFP-Atg8) processing assay revealed a significant defect in the macroautophagic activity of the cho1{Delta} mutant, regardless of the presence or absence of ethanolamine (Etn). Notably, autophagosomes were absent in the cytosol, and macroautophagic bodies were not observed in the vacuoles of the starved cho1{Delta} mutant, underscoring the essential role of PtdSer synthesized using Cho1 in autophagosome biogenesis. In contrast, numerous microautophagic vesicles containing lipid droplets were observed in the vacuoles of cho1{Delta} mutants starved in the presence of Etn, suggesting the crucial role of phosphatidylethanolamine (PtdEtn) synthesized via the Kennedy pathway in microautophagic lipophagy when PtdSer synthesis using Cho1 is disrupted. Given recent evidence pointing to the involvement of the ubiquitination system in various autophagy-related processes, we also examined the role of ubiquitin-conjugating enzyme E2 gene ubc4. Moreover, microautophagic lipophagy was significantly diminished in starved cho1{Delta} yeast with ubc4 knockout. These findings suggest the critical role of Ubc4-mediated ubiquitination in facilitating microautophagic lipophagy of the vacuole in yeast cells.

cell biology↗

bioRxiv2023

Low albumin status accompanies multi-layered immunosuppressive phenotypes in metastatic breast cancer patients

Low albumin status is prevalent in advanced cancer patients, but the pathophysiology associated with this anomaly remains largely unexplored. To address this, we aim to search correlations of albumin levels with the transcriptome against peripheral blood mononuclear cells and the plasma metabolome within the same patients having metastatic breast cancers. We confirm that metastatic breast cancer patients exhibit low albumin levels in varying degrees without prominent systemic inflammation. Our data demonstrate that low albumin levels correlate with transcriptome signatures indicative of "neutrophil activation and T-cell down-regulation," an immunosuppressive phenotype. We also find that immunoregulatory metabolites, such as arginine, are reduced in plasma in an albumin-correlated manner, further corroborating systemic immunosuppression. These results are verified using a mouse model of breast cancer. We conclude that low albumin status in metastatic breast cancer patients accompanies immunosuppressive phenotypes, which is likely unfavorable for anti-cancer immunotherapy and thus can be a cause of unsuccessful treatment outcomes.

cancer biology↗

bioRxiv2022

Serum amyloid alpha 1-2 are not required for systemic inflammation in the 4T1 murine breast cancer model

Cancers induce the production of acute phase proteins such as serum amyloid alpha (SAA) in the liver and cause systemic inflammation. Despite the well-known coincidence of acute phase response and systemic inflammation, the direct roles of SAA proteins in systemic inflammation in the cancer context remains incompletely characterized, particularly in vivo. Here, we investigate the in vivo significance of SAA proteins in systemic inflammation in the 4T1 murine breast cancer model. 4T1 cancers elevate the expression of SAA1 and SAA2, the two major murine acute phase proteins in the liver. The elevation of Saa1-2 correlates with the up-regulation of immune cell-related genes including neutrophil markers. To examine this correlation in detail, we generate mice that lack Saa1-2 and investigate immune-cell phenotypes. RNA-seq experiments reveal that deletion of Saa1-2 does not strongly affect 4T1-induced activation of immune cell-related genes in the liver and bone marrow. Flow cytometry experiments demonstrate the dispensable roles of SAA1-2 in cancer-dependent neutrophil infiltration to the liver. This study clarifies the negligible contribution of SAA1-2 proteins in systemic inflammation in the 4T1 breast cancer model.

cancer biology↗

bioRxiv2022

Murine breast cancers disorganize the liver transcriptome in zonated manners

The spatially organized gene expression program within the liver specifies hepatocyte functions according to their relative distances to the bloodstream (i.e., zonation), contributing to liver homeostasis. Despite the knowledge that solid cancers remotely disrupt liver homeostasis, it remains unexplored whether solid cancers affect liver zonation. Here, using spatial transcriptomics, we thoroughly investigate the abundance and zonation of hepatic genes in cancer-bearing mice. We find that breast cancers affect liver zonation in various distinct manners depending on biological pathways. Aspartate metabolism and triglyceride catabolic processes retain relatively intact zonation patterns, but the zonation of xenobiotic catabolic process genes exhibits a strong disruption. The acute phase response is induced in zonated manners. Furthermore, we demonstrate that breast cancers activate innate immune cells in particular neutrophils in distinct zonated manners, rather than in a uniform fashion within the liver. Collectively, breast cancers disorganize hepatic transcriptomes in zonated manners, thereby disrupting zonated functions of the liver.

cancer biology↗