Biology subjects

Tabata, T.

Publications and source records attributed to Tabata, T..

12 recordsLinked to original sources

bioRxiv2025

Ptpn14 Knockout Mice Reveal Critical Female-Specific Roles for the Hippo Pathway

The Hippo pathway regulates many physiological processes, including development, tumor suppression, and wound healing. One understudied Hippo pathway component is PTPN14, an evolutionarily conserved tyrosine-phosphatase that inhibits YAP/TAZ. While an established tumor suppressor, PTPN14s role in tissue homeostasis has remained unclear. We thus generated Ptpn14-deficient mice and found that only [~]60% of Ptpn14-/- mice survived postnatally, highlighting the importance of PTPN14 for viability, while also enabling the discovery of PTPN14 physiological functions. Ptpn14-/-mice developed debilitating corneal lesions and the uterus defect, hydrometra, as well as heart and kidney abnormalities. Ptpn14-deficiency precipitated an impaired injury response in the cornea and dysregulated YAP signaling in the uterus. Notably, these phenotypes were female-specific, revealing sexually-dimorphic Hippo pathway function through PTPN14. Finally, analysis of human PTPN14 variants suggested that PTPN14s essential roles are conserved in humans, underscoring the importance of our insights for designing therapies to improve womens health.

developmental biology↗

bioRxiv2024

The swarming behaviors of Vorticella

Two Vorticella species undergo a synchronous transition from sessile zooids to motile telotrochs, which swarm enveloped in secreted mucus, subsequently forming dense aggregations on substrates and reverting to the zooid form. This cyclical process recurs on a daily basis. Each species exhibits a unique mode of swarming behavior. We hypothesize that these behaviors may serve to facilitate efficient feeding while concurrently acting as a mechanism for predator avoidance.

animal behavior and cognition↗

bioRxiv2024

UniScore, a unified and universal measure for peptide identification by multiple search engines

We propose UniScore as a metric for integrating and standardizing the outputs of multiple search engines in the analysis of data-dependent acquisition (DDA) data from LC/MS/MS-based bottom-up proteomics. UniScore is calculated from the annotation information attached to the product ions alone by matching the amino acid sequences of candidate peptides suggested by the search engine with the product ion spectrum. The acceptance criteria are controlled independently of the score values by using the false discovery rate based on the target-decoy approach. Compared to other rescoring methods that use deep learning-based spectral prediction, larger amounts of data can be processed using minimal computing resources. When applied to large-scale global proteome data and phosphoproteome data, the UniScore approach outperformed each of the conventional single search engines examined (Comet, X! Tandem, Mascot and MaxQuant). Furthermore, UniScore could also be directly applied to peptide matching in chimeric spectra without any additional filters.

bioinformatics↗

bioRxiv2024

Regulation of virion production by the ORF8 signal peptide across SARS-CoV-2 variants

The open reading frame 8 (ORF8), an accessory protein of SARS-CoV-2, is prone to deletions and mutations across different viral variants, which was first described in several Singapore variants. The reason why viral evolution favors loss or inactivation of ORF8 is not fully understood, although the effects of ORF8 on inflammation, immune evasion, and disease severity have been described. Here we show -using clinical ORF8-deficient viral isolates, virus-like particles (VLPs) and viral replicons- that ORF8 expression dampens viral particle production. ORF8 physically interacts with the viral Spike protein and induces Golgi fragmentation, overall contributing to less virus particle production. Using systematic ORF8 deletions, we mapped the particle-reducing function to its N-terminal signal peptide. Interestingly, this part of ORF8 is severely truncated in the recent XBB.1.5 variant, and when restored, suppresses viral particle production in the context of the entire viral genome. Collectively, our data supports the model that evolutionary pressure exists to delete ORF8 sequence and expression across SARS-CoV-2 variants to fully enable viral particle production. ImportanceSARS-CoV-2 variants continue to emerge worldwide with advantages in replication and immune evasion. Many variants have acquired distinct mutations in independent lineages to abolish ORF8 expression. To understand the molecular mechanisms behind this evolutionary trend, we utilized reverse genetics, molecular virology, and confocal microscopy to show that ORF8 has antiviral functions by dampening viral particle production and inducing Golgi stress during infection. Our data demonstrate that SARS-CoV-2 is continuing its adaptation to optimize viral particle production and other unknown aspects of viral infection.

microbiology↗

bioRxiv2023

Revisiting the role of cAMP in Drosophila aversive olfactory memory formation

In the olfactory aversive conditioning of Drosophila melanogaster, an odor, the conditioned stimulus (CS), is associated with electric shock, the unconditioned stimulus (US). The Rutabaga adenylyl cyclase in Kenyon cells (KCs) of the fly brain synthesizes cAMP, which is believed to serve as the coincidence detector synergistically stimulated by calcium/calmodulin evoked by the odor reception and GS released in response to the dopamine signaling elicited by electric shock. However, live imaging analyses revealed that olfactory stimulation itself prompted the activation of dopaminergic neurons and resulted in the elevation of cAMP levels in KCs that received dopamine, regardless of calcium signaling. This finding raises questions about the longstanding and fundamental comprehension of conditioning mechanisms, as the cAMP levels in conditioned stimulus-positive (CS+) KCs could not be distinguished from those in the rest of the KCs. Our findings suggest that cAMP concentrations do not function as a mnemonic engram to CS+ neurons. Rather, the collective dynamics of cAMP are capable of integratively encoding the valence ascribed to odors being perceived at a given time. Furthermore, our investigation revealed that associative conditioning induces modifications in dopamine levels in response to both CS and US, resulting in alterations in cAMP levels. The increase in cAMP exerts a deleterious effect on the acetylcholine transmission from KCs. Accordingly, we postulate that, during conditioning, cAMP depresses KCs, thereby skewing the valence of the CS+ odor towards a more aversive state for the conditioned flies, and ultimately culminating in the formation of aversive memories.

neuroscience↗

bioRxiv2023

Rapid assembly of SARS-CoV-2 genomes reveals attenuation of the Omicron BA.1 variant through NSP6

Although the SARS-CoV-2 Omicron variant (BA.1) spread rapidly across the world and effectively evaded immune responses, its viral fitness in cell and animal models was reduced. The precise nature of this attenuation remains unknown as generating replication-competent viral genomes is challenging because of the length of the viral genome (30kb). Here, we designed a plasmid-based viral genome assembly and rescue strategy (pGLUE) that constructs complete infectious viruses or noninfectious subgenomic replicons in a single ligation reaction with >80% efficiency. Fully sequenced replicons and infectious viral stocks can be generated in 1 and 3 weeks, respectively. By testing a series of naturally occurring viruses as well as Delta-Omicron chimeric replicons, we show that Omicron nonstructural protein 6 harbors critical attenuating mutations, which dampen viral RNA replication and reduce lipid droplet consumption. Thus, pGLUE overcomes remaining barriers to broadly study SARS-CoV-2 replication and reveals deficits in nonstructural protein function underlying Omicron attenuation.

microbiology↗

bioRxiv2023

SARS-CoV-2 Omicron XBB.1.5 may be a cautionary variant by in silico study

In this research, we aimed to predict the relative risk of the recent new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on the basis of our previous research. We first performed molecular docking simulation analyses of the spike proteins with human angiotensin-converting enzyme 2 (ACE2) to determine the binding affinities to human cells of three new variants of SARS-CoV-2: Omicron BQ.1, XBB, and XBB.1.5 We then investigated the three variants to discover the evolutionary distance of the spike protein gene (S gene) from the Wuhan, Omicron BA.1, and Omicron BA.4/5 variants, to understand the changes in the S gene. The results indicated that the XBB.1.5 variant had the highest binding affinity of the spike protein with ACE2 and the longest evolutionary distance of the S gene. This in silico evidence suggested that the XBB.1.5 variant may produce infections that spread more widely and faster than can infections of preexisting variants.

bioinformatics↗

bioRxiv2022

Accelerating PERx Reaction Enables Covalent Nanobodies for Potent Neutralization of SARS-Cov-2 and Variants

The long-lasting COVID-19 pandemic and increasing SARS-CoV-2 variants demand effective drugs for prophylactics and treatment. Protein-based biologics offer high specificity yet their noncovalent interactions often lead to drug dissociation and incomplete inhibition. Here we developed covalent nanobodies capable of binding with SARS-CoV-2 spike protein irreversibly via proximity-enabled reactive therapeutic (PERx) mechanism. A novel latent bioreactive amino acid FFY was designed and genetically encoded into nanobodies to accelerate PERx reaction rate. After covalent engineering, nanobodies binding with the Spike in the down state, but not in the up state, were discovered to possess striking enhancement in inhibiting viral infection. In comparison with the noncovalent wildtype nanobody, the FFY-incorporated covalent nanobody neutralized both authentic SARS-CoV-2 and its Alpha and Delta variants with potency drastically increased over tens of folds. This PERx-enabled covalent nanobody strategy and uncovered insights on potency increase can be valuable to developing effective therapeutics for various viral infections.

synthetic biology↗

bioRxiv2021

Post-transcriptionally regulated genes are essential for pluripotent stem cell survival

The effects of transcription factors on the maintenance and differentiation of pluripotent stem cells (PSCs) have been well studied. However, the importance of post-transcriptional regulatory mechanisms, which cause the quantitative dissociation of mRNA and protein expression, has not been explored in detail. Here, by combining transcriptome and proteome profiling, we identified 228 post-transcriptionally regulated genes with strict upregulation of the protein level in PSCs. Among them, we found that 84 genes were vital for the survival of PSCs and HDFs, including 20 genes that were specifically necessary for the survival of PSCs. These 20 proteins were upregulated only in PSCs and not in differentiated cells derived from the three germ layers. Subcellular fractionation of the mRNA showed that the expression of most of the 20 proteins was regulated at the mRNA localization stage from the nucleus to the cytoplasm, but their translation efficiency was constant. Together, these results revealed that post-transcriptionally regulated genes have a crucial role in PSC survival.

molecular biology↗

bioRxiv2021

A stress-reduced passaging technique improves the viability of human pluripotent cells

Xeno-free culture systems have expanded the clinical and industrial application of human pluripotent stem cells (PSCs). However, yet some problems, such as the reproducibility among the experiments, remain. Here we describe an improved method for the subculture of human PSCs. The revised method significantly enhanced the viability of human PSCs by lowering DNA damage and apoptosis, resulting in more efficient and reproducible downstream applications such as gene editing, gene delivery, and directed differentiation. Furthermore, the method did not alter PSC characteristics after long-term culture and attenuated the growth advantage of abnormal subpopulations. This robust passaging method minimizes experimental error and reduces the rate of PSCs failing quality control of human PSC research and application. HighlightsO_LIThe revised passaging method significantly increases the viability of human PSCs. C_LIO_LIThe method triggers less DNA damage and apoptosis signals compared to the conventional method. C_LIO_LIThe stress-reduced method improves the results of downstream applications. C_LIO_LIThe method does not alter PSC characters and attenuates the overgrowth of abnormal subpopulations. C_LI

cell biology↗

bioRxiv2021

Rapid assessment of SARS-CoV-2 evolved variants using virus-like particles

Newly evolved SARS-CoV-2 variants are driving ongoing outbreaks of COVID-19 around the world. Efforts to determine why these viral variants have improved fitness are limited to mutations in the viral spike (S) protein and viral entry steps using non-SARS-CoV-2 viral particles engineered to display S. Here we show that SARS-CoV-2 virus-like particles can package and deliver exogenous transcripts, enabling analysis of mutations within all structural proteins and rapid dissection of multiple steps in the viral life cycle. Identification of an RNA packaging sequence was critical for engineered transcripts to assemble together with SARS-CoV-2 structural proteins S, nucleocapsid (N), membrane (M) and envelope (E) into non-replicative SARS-CoV-2 virus-like particles (SC2-VLPs) that deliver these transcripts to ACE2- and TMPRSS2-expressing cells. Using SC2-VLPs, we tested the effect of 30 individual mutations within the S and N proteins on particle assembly and entry. While S mutations unexpectedly did not affect these steps, SC2-VLPs bearing any one of four N mutations found universally in more-transmissible viral variants (P199L, S202R, R203M and R203K) showed increased particle production and up to 10-fold more reporter transcript expression in receiver cells. Our study provides a platform for rapid testing of viral variants outside a biosafety level 3 setting and identifies viral N mutations and viral particle assembly as mechanisms to explain the increased spread of current viral variants, including Delta (N:R203M). One-Sentence SummaryR203M substitution within SARS-CoV-2 N, found in delta variant, improves RNA packaging into virus-like particles by 10-fold.

microbiology↗

bioRxiv2020

Cystal structure of inhibitor-bound human MSPL/TMPRSS13 that can activate high pathogenic avian influenza

Infection of certain influenza viruses is triggered when its hemagglutinin (HA) is cleaved by host cell proteases such as proprotein convertases and type II transmembrane serine proteases (TTSP). HA with a monobasic motif is cleaved by trypsin-like proteases, including TMPRSS2 and HAT, while the multibasic motif found in high pathogenicity avian influenza HA is cleaved by furin, PC5/6, or MSPL. MSPL belongs to the TMPRSS family and preferentially cleaves [R/K]-K-K-R{downarrow} sequences. Here, we solved the crystal structure of the extracellular region of human MSPL in complex with an irreversible substrate-analog inhibitor. The structure revealed three domains clustered around the C-terminal -helix of the SPD. The inhibitor structure and its putative model show that the P1-Arg inserts into the S1 pocket, whereas the P2-Lys and P4-Arg interacts with the Asp/Glu-rich 99-loop that is unique to MSPL. Based on the structure of MSPL, we also constructed a homology model of TMPRSS2, which is essential for the activation of the SARS-CoV-2 spike protein and infection. The model may provide the structural insight for the drug development for COVID-19.

biophysics↗