Biology subjects

Hojo, Y.

Publications and source records attributed to Hojo, Y..

5 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↗

bioRxiv2025

Age-related decline of synaptic plasticity is regulated by neuro-androgen and neuro-estrogen in normal aging of hippocampus

We revealed a good relationship between age-dependent decrease in the hippocampal dendritic spine density and age-dependent decrease in hippocampal androgen and estrogen levels with normal aging of male rats. Approximately 25% decrease in the spine density was observed in hippocampal CA1 region by going from 3 month-old (3m; young adult) to 24 month-old (24m; aged). We found a significant age-induced decrease in hippocampal neuro-androgen levels by going from 3m to 24 m using mass-spectrometric analysis. The hippocampal levels of testosterone (T) and dihydrotestosterone (DHT) dramatically decreased from 17 nM T and 7 nM DHT at 3 m to 17/100 nM T and 7/15 nM DHT at 24 m. On the other hand, hippocampal estradiol (E2) was moderately decreased with aging, from 8 nM at 3 m to 2 nM at 24m. Comprehensive analysis of mRNAs of hippocampal steroidogenic enzymes and receptors showed an age-dependent decrease in their expression levels by approximately 50% (P450(17)), 25% (17-hydroxysteroid dehydrogenase) and 0% (5-reductase and P450arom). Androgen receptor AR was moderately decreased but estrogen receptor ER was not decreased with aging. The 25% decrease in the spine density with aging may be due to a balance between considerably decreased T and DHT levels (spine decrease factor) and remained moderately high E2 level (spine increase factor) in the 24m hippocampus. Aged hippocampus still has moderate capacity of sex-steroid synthesis and their functions. Interestingly, DHT-supplementation and T-supplementation recovered the spine density at 24m.

neuroscience↗

bioRxiv2019

Low temperature transcriptionally modulates natural peel degreening in lemon (Citrus limon L.) fruit independently of endogenous ethylene

AbstractPeel degreening is an important aspect of fruit ripening in many citrus fruit, and earlier studies have shown that it can be advanced either by ethylene treatment or during low temperature storage. However, the important regulators and pathways involved in natural peel degreening remain largely unknown. To understand how natural peel degreening is regulated in lemon (Citrus limon L.) fruit, flavedo transcriptome and physiochemical changes in response to either ethylene treatment or low temperature were studied. Ethylene treatment induced rapid peel degreening which was strongly inhibited by the ethylene antagonist, 1-methylcyclopropene (1-MCP). Compared with 25{degrees}C, moderately low temperatures (5{degrees}C, 10{degrees}C, 15{degrees}C and 20{degrees}C) also triggered peel degreening. Surprisingly, repeated 1-MCP treatments failed to inhibit the peel degreening induced by low temperature. Transcriptome analysis revealed that low temperature and ethylene independently regulated genes associated with chlorophyll degradation, carotenoid metabolism, photosystem proteins, phytohormone biosynthesis and signalling, and transcription factors. On-tree peel degreening occurred along with environmental temperature drops, and it coincided with the differential expression of low temperature-regulated genes. In contrast, genes that were uniquely regulated by ethylene showed no significant expression changes during on-tree peel degreening. Based on these findings, we hypothesize that low temperature plays a prominent role in regulating natural peel degreening independently of ethylene in citrus fruit. HighlightCitrus peel degreening is promoted by low temperature via modulation of multiple genes associated with chlorophyll degradation, carotenoid biosynthesis, photosystem disassembly, phytohormones and transcription factors without involving ethylene signalling.

plant biology↗

bioRxiv2017

Spodoptera exigua caterpillar feeding induces rapid defense responses in maize leaves

Insects such as beet armyworm caterpillars (Spodoptera exigua) cause extensive damage to maize (Zea mays) by consuming foliar tissue. Maize plants respond to such insect attack by triggering defense mechanisms that involve large changes in gene expression and the biosynthesis of specialized metabolites and defense signaling molecules. To investigate dynamic maize responses to herbivore feeding, leaves of maize inbred line B73 were infested with S. exigua caterpillars for 1 to 24 hours, followed by comprehensive transcriptomic and metabolomic characterization. Our results show that the most significant gene expression responses of maize to S. exigua feeding occur at early time points, within 4 to 6 hours after caterpillar infestation. However, both gene expression and metabolite profiles continued changing during the entire 24-hour experiment while photosynthesis genes were gradually decreased. The primary and specilaze metabolism shift maught be temporal and dynamic processes in the infested leaf tissue. We analyzed the effects of mutating genes in two major defense-related pathways, benzoxazinoids (Bx1 and Bx2) and jasmonic acid (Lox8), using Dissociation (Ds) transposon insertions in maize inbred line W22. Together, these results show that maize leaves shift to implementation of chemical defenses within one hour after the initiation of caterpillar attack. Thus, the induced biosynthesis of specialized metabolites can have major effects in maize-caterpillar interactions.\n\nHIGHLIGHTA comprehensive transcriptic and metabolomic profiling time course of maize foliar responses to caterpillar feeding identifies genes for the synthesis of benzoxazinoids and phytohormones.

plant biology↗