Genes to Cells最新文献

Serine-arginine protein kinases (SRPKs) play important roles in diverse biological processes such as alternative splicing and cell cycle. However, the functions of SRPKs in DNA damage response remain unclear. Here we characterized the function of SRPKs homolog Dsk1 in regulating DNA repair in the fission yeast Schizosaccharomyces pombe. We demonstrated that Dsk1 defective mutants of loss of the gene, spacer domain, and kinase activity as well as its overexpression mutant exhibited sensitivities of replication stress. Genetic analysis revealed that the loss of dsk1⁺ compromised the efficiency of homologous recombination (HR) repair, and Dsk1 was probably involved in the Rad52- and Rad51-dependent HR repair pathways. Interestingly, Dsk1 translocated into the nucleus upon replication stress and directly interacted with Rad51-mediator Rad52 and phosphorylated Rad52-Ser365 residue. The Rad52-Ser365 phosphorylation-defective mutant was slightly sensitive to replication stress, and the phosphorylation-mimicking mutants exhibited more sensitivities, which were partially correlated with phenotypes of the loss- and gain-of-function of dsk1⁺. This study uncovers a potential HR repair regulator Dsk1 in response to replication stress and implies that its homolog SRPKs may have the conserved targets and functions in higher eukaryotes.

The 18th International Zebrafish Conference (IZFC2024) took place from August 17 to 21, 2024, at Miyako Messe in Kyoto, Japan. This conference attracted 641 researchers from around the world along with 83 virtual participants, making it the largest gathering since the COVID-19 pandemic. The event featured two keynote lectures, three award lectures, 36 plenary talks, 90 oral presentations, and 374 poster presentations. Participants also engaged in luncheons, workshops, and community sessions, all aimed at exploring innovative technologies, enhancing scientific environments and strengthening connections within the research community. Additionally, the conference included cultural elements that allowed participants to immerse themselves in Japanese traditions, enriching their overall experience. This commitment to blending scientific inquiry with cultural appreciation ensured that participants gained valuable insights into the latest research while enjoying a taste of Japan's rich heritage. Overall, IZFC2024 successfully promoted collaboration and innovation in zebrafish research while celebrating the unique cultural aspects of Japan, making this conference an unforgettable event for everyone involved.

During embryogenesis, organisms function as a robust system that ensures uniformity within individuals, but they lose robustness and develop variations at advanced ages. However, when and how organisms lose this robustness remains largely elusive. Here, we identified a sharp transition from interindividual uniformity to diversity in the appearance and transcriptional features of age-matched Caenorhabditis elegans in midlife. Convolutional neural network analysis of individual appearance alterations revealed that the transition occurs in midlife, which coincides with the cessation of egg-laying activity and increased motility defects. This period represents the transition from the young state, marked by shared homogeneous features among same-age individuals, to the old state, marked by shared among old individuals. Transcriptional coherence within the age-matched individuals shows essentially the same transition, coinciding with the appearance features. These findings provide a new framework for understanding the aging trajectory in C. elegans, demonstrating the occurrence of the loss of robust control over appearance and transcriptional homeostasis in midlife.

Sulforaphane (SFN), an isothiocyanate found in plants of the Brassicaceae family, possesses antioxidant, apoptosis-inducing, and radiosensitizing effects. As one of the mechanisms of cytotoxicity by SFN, SFN has been suggested to be involved in the induction of DNA damage and inhibition of DNA repair. Recently, we reported on the potency of SFN in inducing single-ended double-strand breaks (DSBs) that are caused by the collision of replication forks with single-strand breaks (SSBs). However, the mechanism of SSB accumulation by SFN remains unclear. In this study, we examined the effect of SFN on SSB-inducing factors in HeLa cells. Although the inhibitory effect of SFN on DNA topoisomerase I was not observed, we found that the reduced form of glutathione (GSH; an antioxidant) level was decreased in an SFN concentration-dependent manner. Furthermore, the addition of ascorbic acid partially increased the viability of SFN-treated HeLa cells. We subsequently observed that poly(ADP-ribose) accumulated in SFN-treated HeLa cells, which occurs during early SSB repair. Collectively, these findings suggest that SFN may transiently induce SSBs via reactive oxygen species in HeLa cells.

We previously suggested that the signal transducer and activator of transcription 1 (STAT1) gene is autoregulated in an interferon (IFN)-dependent manner via a distal regulatory region approximately 5.5–6.2 kb upstream of the murine and human STAT1 promoters (designated 5.5URR). Here, we examined whether this IFN-dependent positive feedback mechanism of the STAT1 gene actually functions in cells. First, we created human embryonic kidney 293 cell mutants lacking the IFN-responsive transcription factor binding sites (IFN-stimulated response element and IFN-gamma-activated sequence) within the 5.5URR and stimulated them with IFN-α/γ. The mutants showed a loss of response to IFN, indicating that the 5.5URR is essential for IFN-induced transcriptional enhancement in STAT1 gene expression. Second, we cloned the full-length 11 kb human STAT1 promoter, including the region upstream of the 5.5URR, from the start codon and linked it to a luciferase gene. Reporter assays showed that IFN-α/γ significantly activated the STAT1 promoter via the 5.5URR. Furthermore, recombinant DNA linking the full-length STAT1 promoter to STAT1 cDNA was introduced into STAT1-deficient cells. In vitro reconstitution experiments showed that IFN-α/γ stimulation increased STAT1 protein levels via the 5.5URR. These results demonstrate that the 5.5URR confers IFN-dependent autoregulation of the STAT1 promoter.

Aggregation of alpha-synuclein (α-Syn) is implicated in the pathogenesis of several neurodegenerative disorders, such as Parkinson's disease and Dementia with Lewy bodies, collectively termed synucleinopathies. Thus, tremendous efforts are being made to develop strategies to prevent or inhibit α-Syn aggregation. Here, we genetically engineered fission yeast to express human α-Syn C-terminally fused to green fluorescent protein (GFP) at low and high levels. α-Syn was localized at the cell tips and septa at low-level expression. At high-level expression, α-Syn was observed to form cytoplasmic aggregates. Notably, rapamycin, a natural product that allosterically inhibits the mammalian target of rapamycin (mTOR) by forming a complex with FKBP12, and Torin1, a synthetic mTOR inhibitor that blocks ATP binding to mTOR, markedly reduced the number of cells harboring α-Syn aggregates. These mTOR inhibitors abrogate α-Syn aggregation without affecting α-Syn expression levels. Rapamycin, but not Torin1, failed to reduce α-Syn aggregation in the deletion cells of fkh1⁺, encoding FKBP12, indicating the requirement of FKBP12 for rapamycin-mediated inhibition of α-Syn aggregation. Importantly, the effect of rapamycin was also observed in the cells lacking atg1⁺, a key regulator of autophagy. Collectively, rapamycin abrogates human α-Syn aggregation expressed in fission yeast via an autophagy-independent mechanism mediated by FKBP12.

Acute liver failure is a serious, life-threatening disease. Although the gut microbiota has been considered to play a role in liver failure, the extent to which it is involved in the pathogenesis of this disease has not been fully elucidated to date. Therefore, we here analyzed the importance of the presence of intestinal microbiota in the pathogenesis of acute liver injury, using D-galactosamine (D-GalN)/lipopolysaccharide (LPS)-treated mice, which is a widely used experimental model of acute liver injury. First, administration of the antibiotic polymyxin B markedly alleviated liver injury. Liver injury was also reduced in germ-free mice, leading to the conclusion that the presence of intestinal microbiota aggravates D-GalN/LPS-induced liver injury. The amount of bacteria and LPS transferred from the gut to the blood was not increased by D-GalN/LPS, suggesting that the worsening of liver injury was not simply owing to the entry of bacteria into the circulation. In conclusion, acute liver injury in polymyxin B-pretreated or germ-free mice was ameliorated by modulation of the gut microbiota. Modification of the gut microbiota using polymyxin B may hence have the potential to alleviate acute liver injury in human patients.

Schizophyllum commune, a common wood-decay mushroom known for its extremely high genetic variation and as a rare cause of human respiratory diseases, could be a promising model fungus contributing to both biology and medicine. To better understand its phenotypic variation, we developed an image analysis system that quantifies morphological and physiological traits of mycelial colonies in Petri dishes. This study evaluated growth of six wild and one clinical isolates of Japanese S. commune, subjected to different temperatures and glucose concentrations, including a condition mimicking the human respiratory environment. Our analysis revealed that combinations of two growth indices, area and whiteness, and profiling by clustering algorithms highlighted strain-specific responses. For example, the clinical isolate was the whitest under the respiratory-like condition. We also found that the growth rate was strongly determined by glucose concentration, while the effects of temperature on growth varied among the strains, suggesting that while glucose preference is common in this species, responses to temperature differ between strains. This system showed sufficient sensitivity to detect variation in mycelial growth. Our study provides a key to unraveling morphological and physiological traits behind the high polymorphisms in S. commune, including the ability to colonize the human respiratory tract.