Biology subjects

Shirai, K.

Publications and source records attributed to Shirai, K..

4 recordsLinked to original sources

bioRxiv2024

Florigen-producing cells express FPF1-LIKE PROTEIN 1 that accelerates flowering and stem growth in long days with sunlight red/far-red ratio in Arabidopsis

Seasonal changes in spring induce flowering by expressing the florigen, FLOWERING LOCUS T (FT), in Arabidopsis. FT is expressed in unique phloem companion cells with unknown characteristics. The question of which genes are co-expressed with FT and whether they have roles in flowering remains elusive. Through tissue-specific translatome analysis, we discovered that under long-day conditions with the natural sunlight red/far-red ratio, the FT-producing cells express a gene encoding FPF1-LIKE PROTEIN 1 (FLP1). The master FT regulator, CONSTANS (CO), controls FLP1 expression, suggesting FLP1s involvement in the photoperiod pathway. FLP1 promotes early flowering independently of FT, is active in the shoot apical meristem, and induces the expression of SEPALLATA 3 (SEP3), a key E-class homeotic gene. Unlike FT, FLP1 facilitates inflorescence stem elongation. Our cumulative evidence indicates that FLP1 may act as a mobile signal. Thus, FLP1 orchestrates floral initiation together with FT and promotes inflorescence stem elongation during reproductive transitions.

plant biology↗

bioRxiv2024

CD39 is expressed on functional effector and tissue resident memory CD8+ T cells

The ecto-ATPase CD39 is expressed on exhausted CD8+ T cells in chronic viral infection and has been proposed as a marker of tumor-specific CD8+ T cells in cancer, but the role of CD39 in an effector and memory T cell response has not been clearly defined. We report that CD39 is expressed on antigen-specific CD8+ short-lived effector cells (SLECs), while its co-ecto-enzyme, CD73, is found on memory precursor effector cells (MPEC) in vivo. Inhibition of CD39 enzymatic activity during in vitro T cell priming enhances MPEC differentiation in vivo after transfer and infection. The enriched MPEC phenotype is associated with enhanced tissue resident memory (TRM) establishment in the brain and salivary gland following an acute intranasal viral infection, suggesting that CD39 ATPase activity plays a role in memory CD8+ T cell differentiation. We also show that CD39 is expressed on human and murine TRM across several non-lymphoid tissues and melanoma, while CD73 is expressed on both circulating and resident memory subsets in mice. In contrast to exhausted CD39+ T cells in chronic infection, CD39+ TRM are fully functional when stimulated ex vivo with cognate antigen. This work further expands the identity of CD39 beyond a T cell exhaustion marker.

immunology↗

bioRxiv2023

Cytosolic heme metabolism by alternative localization of heme oxygenase 1 in plant cells

Heme, an organometallic molecule, is widely engaged in oxygen transport, electron delivery, enzymatic reactions, and signal transduction. Additionally, heme serves as a precursor to phytochromobilin, the chromophore of plant phytochrome. Heme oxygenase (HO) initiates the first committed step in heme metabolism. Our transcription start site-sequencing (TSS-seq) revealed that HO1 in Arabidopsis thaliana and Oryza sativa (rice) has two TSSs, producing long (HO1L) and short (HO1S) transcripts, with or without an intact N-terminal plastid transit peptide. HO1L and HO1S products localize in plastids and the cytosol, respectively. In Arabidopsis, HO1L is prevalent in light-exposed shoots, while HO1S is clearly detected in roots and etiolated seedlings. During de-etiolation and early development, HO1L ratio gradually rises and HO1S ratio decreases. Light perception via phytochrome and cryptochrome elevates HO1L ratio and reduce HO1S ratio through the functioning of HY5 and HYH transcription factors, and the suppression of DET1, E3 ubiquitin ligase COP1, and PIFs transcription factors. As expected, HO1L product was able to complement the HO1-deficient mutant gun2 (hy1), but surprisingly, HO1S expression could also restore the short hypocotyl phenotype and high pigment content, and make the mutant recover from the gun phenotype. This indicates the formation of functional holo-phytochrome within these lines. Our work highlights the presence of a cytosolic pathway for heme metabolism, especially during etiolation and early development. Furthermore, it supports the hypothesis that a mobile heme signal is involved in the mediation of retrograde signaling from the chloroplast. Significance StatementIn this research, through both TSS-seq and CAGE-seq, we discovered that the HO1 (GUN2 or HY1) gene in both Arabidopsis and rice has two TSSs, generating HO1L and HO1S transcripts. We reveal that the HO1 TSS regulation pathway is the same as the light signaling pathway. Significantly, our study identifies that a cytosolic heme metabolism pathway is existent in plant cells.

plant biology↗

bioRxiv2019

The effect of sword bean extract on the relationship between rheumatoid arthritis and periodontitis in mice

ObjectivesSeveral studies in humans and experimental animals have reported an interaction between rheumatoid arthritis (RA) and periodontitis (PD). We previously showed that extracts of Canavalia gladiata (sword bean extract, SBE) can treat PD in rats. Here, we investigated the relationship between RA and PD and the effects of SBE in an experimental mouse model. MethodsFemale SKG mice were assigned to eight groups (n=6/group): (1) Untreated controls, (2) RA (induced at 6 weeks of age), (3) PD (induced at 10 weeks of age), (4) RA + PD, (5) SBE (2 mg/ml in drinking water starting at 5 weeks of age), (6) PD + SBE, (7) RA + SBE, and (8) RA + PD + SBE. Mice were sacrificed at 13 weeks of age, and alveolar bone resorption, periodontal tissue inflammation, and paw joint inflammation were assessed by histology and immunohistochemistry. ResultsMice in the RA + PD group exhibited significantly higher inflammation scores in the joint tissues as well as more abundant IL-17-positive cells and cathepsin K-positive osteoclasts in the radial bone compared with the RA mice. Alveolar bone resorption was also significantly more severe in the RA + PD mice than in the PD mice. SBE treatment significantly improved all bone resorption and tissue inflammation scores in mice with RA + PD. ConclusionConcomitant RA and PD exacerbates the tissue destruction symptomatic of each condition. SBE suppresses all parameters evaluated, suggesting that it is has anti-inflammatory activities in both RA and PD.

immunology↗