Biology subjects

Murakoshi, T.

Publications and source records attributed to Murakoshi, T..

6 recordsLinked to original sources

bioRxiv2026

MHC class II in dopaminergic neurons prunes GABAergic synapses in neurodevelopmental disorders

Although the brain was traditionally considered immune-privileged, recent studies show immune factors play key roles in brain function. Dysfunction of these factors is linked to neurodevelopmental disorders, but mechanisms remain unclear. Using a maternal immune activation (MIA) mouse model, we investigated immune-related genes in neurodevelopmental disorder pathogenesis. MIA mice showed increased locomotor activity and disrupted prepulse inhibition. RNA-seq and qPCR analyses revealed persistent increases in major histocompatibility complex class II (MHCII) expression and persistent decreases in GABAergic synapse-related gene expression, particularly glutamate decarboxylase (Gad) expression, in dopaminergic regions. These expressions were negatively correlated, and immunohistochemistry showed MHCII at postsynaptic GABAergic synapses on dopaminergic neurons. Patch-clamp recordings confirmed reduced mIPSC frequency in MIA mice. MHCII knockout mice showed opposite phenotypes, while MHCII overexpression in dopaminergic neurons decreased Gad expression. These results suggest MIA-induced MHCII upregulation enhances pruning of GABAergic synapses on dopaminergic neurons, leading to behavioral deficits.

neuroscience↗

bioRxiv2025

The rhythmic bimodal sensory stimulation in synchronous manner entrains the network oscillation in basolateral amygdala

The state of neural oscillation is important for various brain functions. In the basolateral nucleus of amygdala (BA), the oscillation frequency is accelerated in retrieval of conditioned fear memory. The amygdala receives sensory inputs from associated cortex and thalamus. Therefore, we tried to apply the bimodal sensory stimulation at slow frequency (5 Hz, functional frequency in behavioral context) for the entrainment of the BA oscillation. Young adult rats (P24-30) were stimulated by LED illuminator and acoustic speaker at 1 or 5 Hz for 1 hour. Immediately after the stimulus was finished, BA slices were prepared and whole-cell recording was applied to projection neuron. The slow (0.5-2 Hz) rhythmic IPSCs obtained from the pyramidal neuron was accelerated at [~]4 Hz by synchronous opto-acoustic stimulation at 5 Hz. However, the frequency of the neuron at the later recording did not change in the same slice, suggesting that this induced entrainment is transient and reversible phenomenon. As a result, the power distribution was shifted from 0.1-2 to 2-6 Hz by synchronous bimodal 5 Hz stimulation. The regularity of the interval between IPSCs, quantified by rhythm index and the concentration of power around peak frequency in the power spectrum, was not changed by rhythmic sensory stimulation. These results suggest that synchronous bimodal sensory stimuli control the neuronal oscillation frequency by applying with rhythmicity.

neuroscience↗

bioRxiv2020

Bimolecule detection for Extracellular Vesicle Screening

Extracellular vesicle (EV) has been investigated for use in clinical testing in recent years. Specific EV surface proteins provide distinguishing characteristics, but are insufficient for more detailed classification of EVs. Here, we suggest a novel "Bimolecular surface antigen expressed in EV" (BiEV) as a potential indicator for more efficient EV screening. A BiEV can be identified using a previously developed method, enzyme-mediated activation of radical sources, to label the components proximal (within 20 nm) to a given molecule. We examined the screening of cancer cell-secreted EV (cEV) included in serum EVs from a model mouse for lung cancer. The cEV-specific BiEVs were first identified by through a comparison of serum EVs from wild-type and lung cancer mice, showing that the CHL1-SLC4A1 bimolecule was a significant candidate for cEV-specific BiEV. Enzyme-linked immunosorbent assay quantification of CHL1-SLC4A1 BiEV appeared to suggest a potential for cancer screening of these mice. Using the same protocols, we found that CHL1-caspase 14 BiEV was significantly elevated in lung cancer patients compared with healthy persons. A BiEV strategy may be able to make a contribution to more effective EV screening, resulting in novel biological and clinical applications.

biochemistry↗

bioRxiv2020

Targeted disruption of Pparγ1 promotes trophoblast endoreplication in the murine placenta

In murine placentas, peroxisome proliferator-activated receptor (PPAR) {gamma}1, a nuclear receptor, is abundant at the late stage of pregnancy (E15-E16), but its functional roles are still elusive because PPAR{gamma}-full knockout embryos die early (E10). We generated mice disrupted in only Ppar{gamma}1, one of the two major mRNA splicing variants of PPAR{gamma}1. Ppar{gamma}1- knockout embryos developed normally until 15.5 dpc, but their growth was retarded thereafter and they did not survive. At 15.5 dpc, in the wild-type placentas, intense PPAR{gamma}-immunostaining was detected in sinusoidal trophoblast giant cells (sTGCs), a cell lineage that coordinates the maternal blood microcirculation in the labyrinth, whereas they were absent in the knockouts. Although Ppar{gamma}1-knockout placentas were normal in morphology, we observed severely dilated maternal blood sinuses in the labyrinth. The Ppar{gamma}1-knockout sTGCs had abnormally large nuclei, an enhanced endocycling phenotype, indicating insufficient differentiation. RNA-sequencing of the placentas showed increased expression of genes coding for nucleosome assembly factors. Labyrinthine gene expressions for atypical E2Fs and cyclin E, key drivers for endocycling, were increased >3-fold. These findings suggested that PPAR{gamma}1 plays a key role in endocycle termination.

developmental biology↗

bioRxiv2020

NPC1L1 inhibition disturbs lipid trafficking and induces large lipid droplet formation in intestinal absorptive epithelial cells

Ezetimibe inhibits Niemann-Pick C1-like 1 (NPC1L1) protein, which mediates intracellular cholesterol trafficking from the brush border membrane to the endoplasmic reticulum, where chylomicron assembly takes place in enterocytes or in the intestinal absorptive epithelial cells. Cholesterol is a minor lipid component of chylomicrons; however, whether or not a shortage of cholesterol attenuates chylomicron assembly is unknown. The aim of this study was to examine the effect of NPC1L1 inhibition on trans-epithelial lipid transport, and chylomicron assembly and secretion in enterocytes. Caco-2 cells, an absorptive epithelial model, grown onto culture inserts were given lipid micelles from the apical side, and chylomicron-like triacylglycerol-rich lipoprotein secreted basolaterally were analyzed after a 24-h incubation period in the presence of ezetimibe up to 50 M. The secretion of lipoprotein and apolipoprotein B48 were reduced by adding ezetimibe (30%, p<0.01 and 34%, p<0.05, respectively). Additionally, ezetimibe accelerated intracellular apoB protein degradation by approximately 2.8-fold and activated sterol regulatory element binding protein 2 by approximately 1.5-fold: These are indicators whether the cells are sensing cellular cholesterol shortage. Thus, ezetimibe appeared to limit cellular cholesterol mobilization required for lipoprotein assembly. In such conditions, large lipid droplet formation in Caco-2 cells and the enterocytes in mice were induced, implying that unprocessed triglyceride was sheltered in these compartments. Although ezetimibe did not reduce the post-prandial lipid surge appreciably in triolein-infused mice, the results of the present study indicated that NPC1L1-mediated supply chylomicron with cholesterol may participate in a novel regulatory mechanism for the efficient chylomicron assembly and secretion.

biochemistry↗

bioRxiv2018

Proximity proteomics identifies cancer cell membrane cis-molecular complex as a potential cancer target

Cancer-specific antigens expressed in the cell membrane have been used as targets for several molecular targeted strategies in recent years with remarkable success. To develop more effective cancer treatments, novel targets and strategies for targeted therapies are needed. Here, we examined the cancer cell membrane-resident \"cis-bimolecular complex\" as a possible cancer target (cis-bimolecular cancer target: BiCAT) using proximity proteomics, a technique that has attracted attention in recent years. BiCATs were detected using a previously developed method, termed the enzyme-mediated activation of radical source (EMARS), to label the components proximal to a given cell membrane molecule. EMARS analysis identified some BiCATs, such as close homolog of L1 (CHL1), fibroblast growth factor 3 (FGFR3) and 2 integrin, which are commonly expressed in mouse primary lung cancer cells and human lung squamous cell carcinoma cells. Analysis of cancer specimens from 55 lung cancer patients revealed that approximately half of patients were positive for these BiCATs. In vitro simulation of effective drug combinations used for multiple drug treatment strategy was performed using reagents targeted to BiCAT molecules. The combination treatment based on BiCAT information moderately suppressed cancer cell proliferation compared with single administration, suggesting that the information about BiCATs in cancer cells is profitable for the appropriate selection of the combination among molecular targeted reagents. Thus, BiCAT has the possibility to make a contribution to several molecular targeted strategies in future.

biochemistry↗