Biology subjects

Tokumoto, S.

Publications and source records attributed to Tokumoto, S..

5 recordsLinked to original sources

bioRxiv2023

A Sodium-dependent Trehalose Transporter Contributes to Anhydrobiosis in Insect Cell Line, Pv11

Pv11 is the only animal cell culture that, when preconditioned with a high concentration of trehalose, can be preserved in the dry state at room temperature for more than one year while retaining the ability to resume proliferation. This extreme desiccation tolerance is referred to as anhydrobiosis. Here we identified a novel transporter that contributes to the recovery of Pv11 cells from anhydrobiosis. In general, the SLC5 family of secondary active transporters co-transport Na+ and carbohydrates including glucose. Here we identified a novel transporter STRT1 (sodium-ion trehalose transporter 1) belonging to the SLC5 family that is highly expressed in Pv11 cells and transports trehalose with Na+ dependency. This is the first report of an SLC5 family member that transports a naturally occurring disaccharide, such as trehalose. Knockout of the Strt1 gene significantly reduced the viability of Pv11 cells upon rehydration after desiccation. During rehydration, when intracellular trehalose is no longer needed, Strt1-knockout cells released the disaccharide more slowly than the parent cell line. During rehydration, Pv11 cells became roughly spherical due to osmotic pressure changes, but then returned to their original spindle shape after about 30 min. Strt1-knockout cells, however, required about 50 min to adopt their normal morphology. STRT1 probably regulates intracellular osmolality by releasing unwanted intracellular trehalose with Na+, thereby facilitating the recovery of normal cell morphology during rehydration. STRT1 likely improves the viability of dried Pv11 cells by rapidly alleviating the significant physical stresses that arise during rehydration. Significance StatementThis is the first report of an SLC5 family member, STRT1 (sodium ion trehalose transporter 1), with Na+-dependent trehalose transport activity. A Strt1-knockout cell line revealed that STRT1 likely plays an important role during anhydrobiosis in Pv11 cells: it efficiently discharges unwanted trehalose in the presence of Na+ during rehydration of dried Pv11 cells, effectively reducing intracellular osmolality and thereby restoring cell morphology to a normal state.

biochemistry↗

bioRxiv2020

Cas9-mediated Genome Editing Reveals a Significant Contribution of Calcium Signaling Pathways to Anhydrobiosis in Pv11

Pv11 is an insect cell line established from the midge Polypedilum vanderplanki that exhibits an extreme desiccation tolerance known as anhydrobiosis. Pv11 has also an anhydrobiotic ability which is induced by trehalose treatment. Here we report the successful construction of the genome editing system for Pv11 cells and its application for identifying the signaling pathways in the anhydrobiosis. Using the Cas9-mediated gene knock-in system, we established GCaMP3-stably expressing Pv11 cells to monitor intracellular Ca2+ mobilization. Intriguingly, trehalose treatment evoked a transient increase of cytosolic Ca2+ concentration, and further experiments indicated the contribution of the calmodulin - calcineurin - NFAT pathway to the tolerance for trehalose treatment as well as the desiccation tolerance, while the calmodulin - calmodulin Kinase - CREB pathway conferred only the desiccation tolerance on Pv11 cells. Thus, our results show the critical contribution of the trehalose-induced Ca2+ surge to the anhydrobiosis and the temporal different roles of each signaling pathway.

molecular biology↗

bioRxiv2020

Development of a Tet-On inducible expression system for the anhydrobiotic cell line, Pv11

The Pv11 cell line established from an African chironomid, Polypedilum vanderplanki, is the only cell line tolerant to complete desiccation. In Pv11 cells, a constitutive expression system for Pv11 cells was previously exploited and several reporter genes were successfully expressed. Here we report the identification of an effective minimal promoter for Pv11 cells and its application to the Tet-On inducible expression system. First, using a luciferase reporter assay, we showed that a 202 bp deletion fragment derived from the constitutively active 121-promoter functions in Pv11 cells as an appropriate minimal promoter with the Tet-On inducible expression system. The AcGFP1 protein was also successfully expressed in Pv11 cells using the inducible system. In addition to these reporter genes, avian myeloblastosis virus reverse transcriptase subunit (AMV RT), which is one of the most widely commercially available RNA-dependent DNA polymerases, was successfully expressed through the inducible expression system and its catalytic activity was verified. These results demonstrate the establishment of an inducible expression system in cells that can be preserved in the dry state and highlight a possible application to the production of large and complex proteins. HighlightsO_LIA 202 bp-deletion fragment derived from a constitutively active promoter was identified as a minimal promoter in Pv11 cells. C_LIO_LIA Tet-On inducible expression system was developed for Pv11 cells using the minimal promoter. C_LIO_LITypical reporter genes (GFP and luciferase) and an enzyme with complex structure, i.e. a viral reverse transcriptase, were successfully and inducibly expressed in Pv11 cells using the Tet-On system. C_LI

bioengineering↗

bioRxiv2019

Intracellular localization and gene expression analysis provide new insights on LEA proteins diversity in anhydrobiotic midge

Anhydrobiosis, an adaptive ability to withstand complete desiccation, is in insects limited to a single species: the nonbiting midge Polypedilum vanderplanki (the sleeping chironomid). Evolution of anhydrobiosis in a single representative of a large genus is associated with drastic changes in genome structure, including the emergence of new multimember gene families directly involved in desiccation tolerance. Among them, Late Embryogenesis Abundant (LEA) proteins, which protect other proteins from aggregation caused by desiccation, are believed to originate via horizontal gene transfer from a bacterial donor. To obtain new insights on the biological background of the expanded 27-member LEA protein group in P. vanderplanki, we investigated the expression of corresponding genes in a P. vanderplanki-derived cell line, capable of anhydrobiosis, in a normal state and during induction of desiccation tolerance. We found that all LEA proteins genes identified in P. vanderplankis genome except PvLea16 and PvLea17 are also expressed in Pv11 cells. Their expression was elevated in response to anhydrobiosis-inducing trehalose treatment. Expression patterns of PvLea genes were well preserved in Pv11 cells in comparison to P. vanderplankis larvae both in the control group and during the anhydrobiosis cycle. We also investigated localization of LEA proteins in Pv11 cells and Sf9 cells and found a different level of conservation in intracellular localization of the protein expressed in mammalian and insect cells.

molecular biology↗

bioRxiv2019

Three-dimensional analysis of β-cell proliferation by a novel mouse model

Inducing {beta}-cell proliferation could inhibit diabetes progression. Many factors have been suggested as potential {beta}-cell mitogens, but their impact on {beta}-cell replication has not been confirmed due to the lack of a standardized {beta}-cell proliferation assay. In this study, we developed a novel method that specifically labels replicating {beta} cells and yields more reproducible results than current immunohistochemical assays. We established a mouse line expressing the fluorescent ubiquitination-based cell cycle indicator (Fucci2a) reporter only in {beta} cells through Cre-mediated recombination under the control of the rat insulin promoter (RIP-Cre;Fucci2aR). Three-dimensional imaging of optically cleared pancreas tissue from these mice enabled the quantification of replicating {beta} cells in islets and morphometric analysis of islets following mitogen treatment. Intravital imaging of RIP-Cre;Fucci2aR mice revealed cell cycle progression of {beta} cells. Thus, this novel mouse line is a powerful tool for spatiotemporal analysis of {beta}-cell proliferation in response to mitogen stimulation.

cell biology↗