Biology subjects

Inouye, K.

Publications and source records attributed to Inouye, K..

4 recordsLinked to original sources

bioRxiv2024

E-cigarettes increase the risk of adenoma formation in murine colorectal cancer model.

BackgroundE-cigarettes (E.cigs) cause inflammation and damage to human organs, including the lungs and heart. In the gut, E.cig vaping promotes inflammation and gut leakiness. Further, E.cig vaping increases tumorigenesis in oral and lung epithelial cells by inducing mutations and suppressing host DNA repair enzymes. It is well known that cigarette (cig) smoking increases the risk of colorectal cancer (CRC). To date, it is unknown whether E.cig vaping impacts CRC development. MethodsA mouse model of human familial adenomatous polyposis (CPC-APC) was utilized wherein a mutation in the adenomatous polyposis coli (APC) gene, CDX2-Cre-APCMin/+, leads to the development of colon adenomas within 16 weeks. Mice were exposed to air (controls), E.cig vaping, cig, or both (dual exposure). After 4 weeks of 2-hour exposures per day (1 hour of each for dual exposures), the colon was collected and assessed for polyp number and pathology scores by microscopy. Expression of inflammatory cytokines and cancer stem cell markers were quantified. DNA damage such as double-strand DNA breaks was evaluated by immunofluorescence, western blot and gene-specific long amplicon qPCR. DNA repair enzyme levels (NEIL-2, NEIL-1, NTH1, and OGG1) were quantified by western blot. Proliferation markers were assessed by RT-qPCR and ELISA. ResultsCPC-APC mice exposed to E.cig, cig, and dual exposure developed a higher number of polyps compared to controls. Inflammatory proteins, DNA damage, and cancer stemness markers were higher in E-cig, cig, and dual-exposed mice as well. DNA damage was found to be associated with the suppression of DNA glycosylases, particularly with NEIL-2 and NTH1. E.cig and dual exposure both stimulated cancer cell stem markers (CD44, Lgr-5, DCLK1, and Ki67). The effect of E.cigs on polyp formation and CRC development was less than that of cigs, while dual exposure was more tumorigenic than either of the inhalants alone. ConclusionE.cig vaping promotes CRC by stimulating inflammatory pathways, mediating DNA damage, and upregulating transcription of cancer stem cell markers. Critically, combining E.cig vaping with cig smoking leads to higher levels of tumorigenesis. Thus, while the chemical composition of these two inhalants, E.cigs and cigs, is highly disparate, they both drive the development of cancer and when combined, a highly common pattern of use, they can have additive or synergistic effects.

cancer biology↗

bioRxiv2023

BAC Transgenic Expression of Human TREM2-R47H Remodels Amyloid Plaques but Unable to Reprogram Plaque-associated Microglial Reactivity in 5xFAD Mice

BackgroundGenetic study of late-onset Alzheimers disease (AD) reveals that a rare Arginine-to-Histamine mutation at amino acid residue 47 (R47H) in Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) results in increased disease risk. TREM2 plays critical roles in regulating microglial response to amyloid plaques in AD, leading to their clustering and activation surrounding the plaques. We previously showed that increasing human TREM2 gene dosage exerts neuroprotective effects against AD-related deficits in amyloid depositing mouse models of AD. However, the in vivo effects of the R47H mutation on human TREM2-mediated microglial reprogramming and neuroprotection remains poorly understood. MethodHere we created a BAC transgenic mouse model expressing human TREM2 with the R47H mutation in its cognate genomic context (BAC-TREM2-R47H). Importantly, the BAC used in this study was engineered to delete critical exons of other TREM-like genes on the BAC to prevent confounding effects of overexpressing multiple TREM-like genes. We crossed BAC-TREM2- R47H mice with 5xFAD [1], an amyloid depositing mouse model of AD, to evaluate amyloid pathologies and microglial phenotypes, transcriptomics and in situ expression of key TREM2-dosage dependent genes. We also compared the key findings in 5xFAD/BAC-TREM2-R47H to those observed in 5xFAD/BAC-TREM2 mice. ResultBoth BAC-TREM2 and BAC-TREM2-R47H showed proper expression of three splicing isoforms of TREM2 that are normally found in human. In 5xFAD background, elevated TREM2-R47H gene dosages significantly reduced the plaque burden, especially the filamentous type. The results were consistent with enhanced phagocytosis and altered NLRP3 inflammasome activation in BAC- TREM2-R47H microglia in vitro. However, unlike TREM2 overexpression, elevated TREM2- R47H in 5xFAD failed to ameliorate cognitive and transcriptomic deficits. In situ analysis of key TREM2-dosage dependent genes and microglial morphology uncovered that TREM2-R47H showed a loss-of-function phenotype in reprogramming of plaque-associated microglial reactivity and gene expression in 5xFAD. ConclusionOur study demonstrated that the AD-risk variant has a previously unknown, mixture of partial and full loss of TREM2 functions in modulating microglial response in AD mouse brains. Together, our new BAC-TREM2-R47H model and prior BAC-TREM2 mice are invaluable resource to facilitate the therapeutic discovery that target human TREM2 and its R47H variant to ameliorate AD and other neurodegenerative disorders.

neuroscience↗

bioRxiv2022

Influence of temperature on growth and development of dictyostelid slime moulds and its implication on the evolution of cold-tolerance

Environmental temperature is a major determinant of microbial life. Dictyostelids are soil amoebae capable of multicellular social behaviour upon starvation. They inhabit in a variety of environments from the tundra to the tropics, but how they have adapted to environmental temperature remains largely unknown. In this study, the effects of temperature on the growth and multicellular development of 36 dictyostelid species (58 strains/isolates) were examined. More than half of the species showed maximal growth and normal development at 28{degrees}C or above, whereas some could grow and develop at 4{degrees}C, or even at 0{degrees}C. Many of the isolates examined were from areas with temperatures far lower than their preferred range over a large part of the year. There was a significant correlation between thermal characteristics and phylogeny. Over 150 known dictyostelid species are divided into several taxonomic groups. Our phylogenetic analysis indicated that cold-tolerance evolved independently in major clades, most prominently in group 4 (genus Dictyostelium according to the new classification by Sheikh et al.), which contains many species that are often found in subarctic regions. These results suggest that ancestors that have acquired cold-tolerance expanded their ranges into cooler areas where they could proliferate and develop during summer and survive the severe winter.

evolutionary biology↗

bioRxiv2020

Aberrant Ca2+ homeostasis in adipocytes links inflammation to metabolic dysregulation in obesity

Chronic metabolic inflammation is a key feature of obesity, insulin resistance and diabetes, although the initiation and propagation mechanisms of metaflammation are not fully established, particularly in the adipose tissue. Here we show that in adipocytes, altered regulation of the Ca2+ channel inositol triphosphate receptor (IP3Rs) is a key, adipocyte-intrinsic, event involved in the emergence and propagation of inflammatory signaling and the resulting insulin resistance. Inflammation, either induced by cytokine exposure in vitro or by obesity in vivo lead to increased expression and activity of IP3Rs in adipocytes in a JNK-dependent manner. This results in increased cytosolic Ca2+ and impaired insulin action. In mice, adipocyte-specific loss of IP3R1/2 protected against adipose tissue inflammation and insulin resistance despite significant diet-induced weight gain. Thus, this work reveals that IP3R over-activation and the resulting increase in cytosolic Ca2+ is a key link between obesity, inflammation and insulin resistance, and suggests that approaches to target adipocyte Ca2+ homeostasis may offer new therapeutic opportunities against metabolic diseases, especially since GWAS studies also implicate this locus in human obesity.

physiology↗