Biology subjects

Shin, H.-S.

Publications and source records attributed to Shin, H.-S..

6 recordsLinked to original sources

bioRxiv2025

Stabilization of the trimeric pre-fusion structures of influenza H1 and H9 hemagglutinins by mutations in the stem helices

Stabilizing the pre-fusion structures of antigenic proteins can enhance the effectiveness of antiviral vaccines. The pre-fusion form of hemagglutinin (HA) from the influenza virus typically adopts a stable trimeric structure. However, the recombinant ectodomain of HA from the A/California/04/2009 (H1N1) influenza virus formed a monomer in solution rather than the expected trimer. To promote trimer formation in the pre-fusion conformation, we redesigned five amino acid residues in the stem region of HA that are involved in trimerization. The engineered HA protein formed a stable trimer at both pH 8.0 and pH 5.5. Additionally, the thermal stability of the modified protein improved, as indicated by an approximately ten-degree increase in its denaturation temperature. Cryo-EM analysis at 2.2 [A] resolution confirmed that the mutant HA protein adopted the pre-fusion structure. Furthermore, the stabilized mutant exhibited enhanced immunogenicity in mice. We applied the same optimization strategy to the HA proteins from A/Malaysia/1706215/2007 (H1N1) and A/swine/Hong Kong/2106/98 (H9N2). These engineered proteins demonstrated increased thermal stability and retained a trimeric pre-fusion structure, as confirmed by cryo-EM analysis. Extending this optimization strategy to the equivalent five residues in hemagglutinins from six additional group 1 influenza viruses successfully stabilized their trimeric structures.

biophysics↗

bioRxiv2025

TMEM145 is a key component in stereociliary link structures of outer hair cells

Outer hair cells (OHCs) in the cochlea contain specialized stereociliary structures essential for auditory function. These include horizontal top connectors (HTCs), linking adjacent stereocilia and tectorial membrane-attachment crowns (TM-ACs), anchoring the tallest stereocilia to the tectorial membrane. The known molecular components of these structures, such as stereocilin, otogelin, otogelin-like, and tubby, lack transmembrane domains, suggesting the existence of anchoring proteins. This study identified TMEM145, a transmembrane protein with a Golgi dynamics (GOLD) domain, as a crucial OHC stereocilia component. TMEM145 was expressed in both OHCs and spiral ganglion neurons, with specific localization to TM-ACs and HTCs in OHCs. Tmem145 knockout (KO) mice exhibited profound hearing impairment at three weeks of age, with complete loss of distortion product otoacoustic emissions, indicating OHC dysfunction. Immunostaining and scanning electron microscopy revealed the absence of TM-ACs and HTCs in Tmem145 KO mice. In heterologous cell systems, TMEM145 interacted with stereocilin and tubby, facilitating their extracellular secretion. TMEM145 was undetectable in stereocilin KO and tubby mutant mice, indicating interdependence among these proteins. These findings establish TMEM145 as an essential membrane protein for the structural integrity of OHC stereocilia, providing insights into the molecular architecture of cochlear hair cells and their role in auditory function.

neuroscience↗

bioRxiv2023

Mediodorsal thalamic nucleus mediates resistance to ethanol through Cav3.1 T-type Ca2+ regulation of neural activity

Thalamocortical activity is known to orchestrate sensory gating and consciousness switching. The precise thalamic regions involved, or the firing patterns related to the unconsciousness remain unclear. Interestingly, the highly-expressed thalamic T-type calcium currents have been considered as a candidate for the ionic mechanism for the generation of thalamo-cortically-driven change in conscious state. Here, we tested the hypothesis that Cav3.1 T-type channels in the mediodorsal thalamic nucleus (MD) might control neuronal firing during unconsciousness using Cav3.1 T-type channel knock-out (KO) and knock-down (KD) mice under natural sleep and ethanol-induced unconsciousness. During natural sleep, the MD neurons in KO mice showed general characteristics of sustained firing across sleep stages. We found that KO and MD-specific KD mice showed enhanced resistance to ethanol. During ethanol-induced unconscious state, wild-type (WT) MD neurons showed a significant reduction in neuronal firing from baseline with increased burst firing, whereas Cav3.1 KO neurons showed well sustained neural firing, within the level of wakefulness, and no burst firing. Further, 20 Hz optogenetic and electrical activation of MD neurons mimicked the ethanol resistance behavior in WT mice. These results suggest that maintaining MD neural firing at a wakeful level is sufficient to induce resistance to ethanol-induced hypnosis in WT mice. This work has important implications for the design of treatments for consciousness disorders using thalamic stimulation of deeper nuclei including the targeting of the mediodorsal thalamic nucleus. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=161 HEIGHT=200 SRC="FIGDIR/small/558585v3_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@1ad68ccorg.highwire.dtl.DTLVardef@1bb698aorg.highwire.dtl.DTLVardef@10de4f0org.highwire.dtl.DTLVardef@1314b27_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

Dynamic switching between distinct oscillatory rhythms in prefrontal-amygdala circuits for dimorphic defensive behaviors under natural threats

The medial prefrontal cortex (mPFC) and basolateral amygdala (BLA) are involved in the regulation of defensive behavior under threat, but their engagement in flexible behavior shifts remains unclear. Here, we report the oscillatory activities of mPFC-BLA circuit in reaction to a naturalistic threat, created by a predatory robot in mice. Specifically, we found dynamic frequency tuning among two different theta rhythms ([~]5 or [~]10 Hz) was accompanied by agile changes of two different defensive behaviors (freeze or flight). By analyzing flight trajectories, we also found that high beta ([~]30 Hz) is engaged in the top-down process for goal-directed flights and accompanied by a reduction in fast gamma (60-120 Hz, peak near 70 Hz). The elevated beta nested the fast gamma activity by its phase more strongly. Our results suggest that the mPFC-BLA circuit has a potential role in oscillatory gear shifting allowing flexible information routing for behavior switches. HighlightsO_LIWhen threatened, mice take quick defensive behaviors such as freeze or flight. C_LIO_LImPFC-BLA theta tunes its frequency at 5 or 10 Hz for freeze or flight, respectively. C_LIO_LILow and high theta rhythms in mPFC-BLA emerge in a mutually exclusive way. C_LIO_LImPFC-driven beta emerges during goal-directed flights, coordinating fast gamma in BLA. C_LI eTOC BlurbHan et al. presents neural dynamics of mPFC-BLA network for freeze-or-flight defensive behaviors under naturalistic threats. Tuning the theta frequency in the mPFC-BLA network is for fast and agile actions under a naturalistic threat, and mPFC-driven beta oscillatory burst is for strategic action.

neuroscience↗

bioRxiv2017

LARGE, an AMPA receptor interactor, plays a large role in long-term memory formation by driving homeostatic scaling-down

Dynamic trafficking of AMPA-type glutamate receptor (AMPA-R) in neuronal cells is a key cellular mechanism for learning and memory in the brain, which is regulated by AMPA-R interacting proteins. LARGE, a protein associated with intellectual disability, was found to be a novel component of the AMPA-R protein complex in our proteomic study. Here, our functional study of LARGE showed that during homeostatic scaling-down, increased LARGE expression at the Golgi apparatus (Golgi) negatively controlled AMPA-R trafficking from the Golgi to the plasma membrane, leading to downregulated surface and synaptic AMPA-R targeting. In LARGE knockdown mice, long-term potentiation (LTP) was occluded by synaptic AMPA-R overloading, resulting in impaired long-term memory formation. These findings indicate that the fine-tuning of AMPA-R trafficking by LARGE at the Golgi is critical for memory stability in the brain. Our study thus provides novel insights into the pathophysiology of brain disorders associated with intellectual disability.

neuroscience↗

bioRxiv2017

Multiple reference genome sequences of hot pepper reveal the massive evolution of plant disease resistance genes by retroduplication

Transposable elements (TEs) provide major evolutionary forces leading to new genome structure and species diversification. However, the role of TEs in the expansion of disease resistance gene families has been unexplored in plants. Here, we report high-quality de novo genomes for two peppers (Capsicum baccatum and C. chinense) and an improved reference genome (C. annuum). Dynamic genome rearrangements involving translocations among chromosome 3, 5 and 9 were detected in comparison between C. baccatum and the two other peppers. The amplification of athila LTR-retrotransposons, members of the gypsy superfamily, led to genome expansion in C. baccatum. In-depth genome-wide comparison of genes and repeats unveiled that the copy numbers of NLRs were greatly increased by LTR-retrotransposon-mediated retroduplication. Moreover, retroduplicated NLRs exhibited great abundance across the angiosperms, with most cases lineage-specific and thus recent events. Our study revealed that retroduplication has played key roles in the emergence of new disease-resistance genes in plants.

plant biology↗