Biology subjects

Konno, A.

Publications and source records attributed to Konno, A..

15 recordsLinked to original sources

bioRxiv2026

The vagus nerve drives cognitive function through the default mode network

The afferent vagus nerve transmits interoceptive signals to the brain but a systematic understanding of how vagal signals affect brain-wide neuronal dynamics remains elusive. Here, comprehensive spatiotemporal analyses across the entire mouse brain revealed that vagus nerve stimulation activated neuronal ensembles within the default mode network (DMN). In contrast, vagal-independent mechanisms predominantly affected the salience network. The vagal-DMN association was mediated by locus coeruleus neuronal subpopulations. Selective activation or silencing of vagal-responsive DMN neuronal ensembles replicated or abolished VNS-induced enhancement of cognitive behaviors and progressive problem-solving behaviors. These findings establish a unifying framework for how the vagus nerve drives cognitive functions by engaging the DMN.

neuroscience↗

bioRxiv2025

A compact glutamic acid decarboxylase 67 promoter enables inhibitory neuron-targeted AAV gene therapy for treatment-resistant epilepsy

Epilepsy often becomes treatment-resistant, partly due to impaired inhibitory neurotransmission and reduced {gamma}-aminobutyric acid (GABA) function. Enhancing inhibitory neuron activity via gene therapy may restore excitation-inhibition (E/I) balance. We developed a compact 410-bp glutamic acid decarboxylase 67 promoter (cmGAD67) that enables strong, selective transgene expression in inhibitory neurons while preserving AAV packaging capacity. When delivered systemically, AAV vectors carrying cmGAD67 preferentially targeted parvalbumin interneurons and supported effective circuit manipulation. To evaluate therapeutic potential, we expressed glutamic acid decarboxylase 65 (GAD65) under cmGAD67 (AAV-GAD65) in pentylenetetrazole (PTZ) epilepsy models. Systemic AAV-GAD65 suppressed abnormal delta oscillations, reduced seizure-like events, normalized anxiety-like behavior, and improved survival in a severe PTZ paradigm. Biochemical analyses confirmed increased cortical and hippocampal GABA levels, linking behavioral and electrophysiological improvements to enhanced inhibitory neurotransmitter synthesis. Prior clinical evidence indicates that AAV-GAD65 delivery to the subthalamic nucleus is safe and effective in Parkinsons disease. Building on this foundation, our findings establish the cmGAD67 promoter as a powerful platform for inhibitory neuron-targeted AAV gene therapy and highlight AAV-cmGAD67-GAD65 as a promising approach for treatment-resistant epilepsy and other disorders involving disrupted E/I balance.

neuroscience↗

bioRxiv2025

VCAP-102 Achieves Exceptional BBB Penetration in Marmosets After Ten Years of AAV Capsid Evaluation

Efficient passage of adenoassociated virus (AAV) vectors across the blood-brain barrier (BBB) is essential for achieving broad central nervous system transduction following systemic delivery. Since PHP.B was reported in 2016 to exhibit high BBB permeability in C57BL/6J mice, many BBB-penetrant capsids have been developed, yet their performance often varies substantially across species. From 2016 to 2025, we produced each newly reported BBB-penetrant capsid as its sequence became available and evaluated it under standardized intravenous administration conditions in marmosets. This included PHP.B, PHP.eB, AAV-F, CAP-B22, CAP-B10, CPP.16, CAP-Mac, and BR1N. Although several of these capsids have been reported to penetrate the marmoset BBB, none reproduced these effects under our unified evaluation conditions. We also pursued several directed-evolution approaches to engineer AAV9-based variants with improved BBB permeability; however, none surpassed AAV9. In 2025, VCAP-102 was reported as an AAV9-derived capsid with BBB permeability in mice and non-human primates. When evaluated using our standardized framework, VCAP-102 consistently mediated markedly stronger and more widespread whole-brain transduction than AAV9 across all three animals tested. These findings provide a decade-long, systematic assessment of BBB-penetrant AAV capsids in marmosets and identify VCAP-102 as a highly promising candidate for future systemically delivered AAV-based gene therapies.

neuroscience↗

bioRxiv2025

Establishment of spinocerebellar ataxia type 34 model mice accompanied by early glial activation and degeneration of cerebellar neurons

Spinocerebellar ataxia type 34 (SCA34) is an autosomal dominant neurodegenerative disease primarily characterized by progressive cerebellar atrophy and ataxia, frequently accompanied by cognitive dysfunction and erythrokeratodermia variabilis. In 2014, missense mutations in the gene encoding elongation of very long chain fatty acids protein 4 (ELOVL4) were identified as the causative gene for SCA34. ELOVL4, which is involved in the synthesis of very long chain fatty acids, is highly expressed in the cerebellum compared to other brain regions, with predominant expression in neurons. We attempted to establish a mouse model of SCA34 by expressing mutant ELOVL4 in cerebellar neurons using adeno-associated virus (AAV) vectors and to elucidate the underlying pathogenic mechanisms. Expression of W246G mutant ELOVL4 successfully induced progressive motor dysfunction beginning at two weeks post-AAV vector injection. Immunohistochemical analyses revealed that the degeneration of cerebellar Purkinje cells and neurons in the deep cerebellar nuclei (DCN) paralleled the observed motor decline. Importantly, microglial activation was detected in the molecular layer of the cerebellar cortices and the DCN prior to the onset of both neurodegeneration and motor dysfunction. Furthermore, after the onset of motor symptoms, the SCA34 model mice exhibited decreased synaptic inputs from climbing fibers to Purkinje cells, as well as reduced inputs from Purkinje cells to DCN neurons. These findings suggest that early microglial activation and the resulting synaptic disturbance are critical preceding events that lead to the progressive cerebellar neurodegeneration and motor dysfunction observed in this SCA34 mouse model.

neuroscience↗

bioRxiv2025

Functional and structural profiling of circulation via genetically encoded modular fluorescent probes.

Sustained labeling of fluids is crucial for their investigation in animal models. Here, we introduce a mouse line (Alb-mSc-ST), where blood and interstitial fluid are labeled with the red fluorescent protein mScarlet and SpyTag. The SpyTag-SpyCatcher technology is exploited to monitor circulating fluid properties by biosensors or detect blood-brain barrier disruption. This approach represents a valuable tool for studying vascular structure, permeability and microenvironment in body organs in vivo.

neuroscience↗

bioRxiv2024

Optimization of microRNA Target Sequence Arrangement in AAV Vectors Dramatically Enhances Specificity and Efficiency of Transgene Expression in Cortical Microglia

Microglia play a critical role in diseases such as Alzheimers and stroke, making them a significant target for therapeutic intervention. However, due to their immune functions in detecting and combating viral invasion, efficient gene delivery to microglia remains challenging. We achieved specific and efficient gene delivery to microglia using an adeno- associated virus (AAV) vector designed for this purpose. This microglia-targeting AAV vector includes the mouse microglia/macrophage-specific ionized calcium-binding adaptor molecule 1 (mIba1) promoter, green fluorescent protein (GFP), microRNA target sequences (miR.Ts), woodchuck hepatitis virus posttranscriptional regulatory element (WPRE), and polyadenylation (polyA) signal, positioned between inverted terminal repeats. When miR.Ts were placed downstream of WPRE (between WPRE and polyA), gene expression occurred not only in microglia but also in a substantial number of neurons. However, when miR.Ts were positioned upstream of WPRE (between GFP and WPRE) or on both sides of WPRE, neuronal expression was significantly suppressed, resulting in selective GFP expression in microglia. Notably, positioning miR.Ts on both sides of WPRE achieved over 90% specificity and more than 60% efficiency in transgene expression in microglia three weeks after viral administration. This vector also enabled GCaMP expression in microglia, facilitating real-time monitoring of calcium dynamics and microglial process activity in the cortex. Additionally, intravenous administration of this vector with the blood-brain barrier-penetrant AAV-9P31 capsid variant resulted in extensive GFP expression selectively in microglia throughout the brain. These findings establish this AAV vector system as a robust tool for long-term, specific, and efficient gene expression in microglia.

neuroscience↗

bioRxiv2024

Facial Coloration as a Social Signal in a Neotropical Cichlid: Testing the Facial Expression Hypothesis

The face is a uniquely distinctive stimulus, encapsulating a wealth of information. Among the myriad of social cues conveyed by the face, emotional signals, known as facial expressions, are paramount not only for humans but also for numerous social animals. The evolution of facial expressions in these animals can also manifest in taxa other than mammals, as suggested by various studies highlighting the socio-ecological benefits of facial expressions. In this study, we elucidated the social function of facial coloration, determined by melanophores, in the neotropical social cichlid Symphysodon aequifasciatus. In this species, facial coloration exhibits instantaneous changes in response to varying social contexts. Through behavioral observations and experimental manipulation, we confirmed that facial coloration in S. aequifasciatus serves to attenuate unnecessary aggressive competition among conspecifics. Furthermore, we observed that the facial area subjected to coloration in this species is innervated by the adenosine triphosphate- and noradrenaline-ergic nervous system. These findings indicated that facial expression in S. aequifasciatus depends on the sympathetic nervous system and has evolved independently of mammalian facial expressions. Our study highlights teleost fishes as valuable animal models for exploring the universality of facial expressions and their underlying cognitive mechanisms in vertebrates.

animal behavior and cognition↗

bioRxiv2024

Optimal AAV capsid/promoter combinations to target specific cell types in the common marmoset cerebral cortex

To achieve cell type-specific gene expression, using target cell-tropic AAV capsids is advantageous. However, their tropism across brain cell types remains unexplored in non-human primates. We assessed the tropism of nine AAV serotype capsids (AAV1, 2, 5, 6, 7, 8, 9, rh.10 (rh10), and DJ) on marmoset cerebral cortical cell types. Marmoset cerebral cortex was injected with different serotype AAVs expressing enhanced GFP (EGFP) by the ubiquitous chicken {beta}-actin hybrid (CBh) promoter. After 4 weeks, all nine AAV capsid vectors, especially AAV9 and AAVrh10, caused highly neuron-selective EGFP expression. Some AAV capsids, including AAV5, caused EGFP expression in oligodendrocytes to a lesser extent, with minimal or no expression in astrocytes and microglia. Different ubiquitous CMV and CAG promoters showed similar neuron-predominant transduction. Conversely, all nine AAV capsid vectors with the astrocyte-specific hGFA(ABC1D) promoter selectively transduced astrocytes, except AAV5, which transduced oligodendrocytes modestly. Oligodendrocyte-specific mouse myeline basic protein (mMBP) promoter in AAV5 vectors transduced oligodendrocytes specifically and efficiently. Our results suggest optimal combinations of capsids and promoters for cell type-specific expression: AAV9 or AAVrh10 and ubiquitous CBh, CMV, or CAG promoter for neuron-specific transduction; AAV2 or 7 and hGFA(ABC1D) promoter for astrocyte-specific transduction; and AAV5 and mMBP promoter for oligodendrocyte-specific transduction.

neuroscience↗

bioRxiv2023

Virally induced CRISPR/Cas9-based knock-in of fluorescent albumin allows long-term visualization of cerebral circulation in infant and adult mice

Albumin, a protein produced by liver hepatocytes, represents the most abundant protein in blood plasma. We have previously engineered a liver-targeting adeno-associated viral vector (AAV) that expresses fluorescent protein-tagged albumin to visualize blood plasma in mice. While this approach is versatile for imaging in adult mice, transgene expression vanishes when AAV is administered in neonates due to dilution of the episomal AAV genome in the rapidly growing liver. Here, we use CRISPR/Cas9 genome editing to insert the fluorescent protein mNeonGreen (mNG) gene into the albumin (Alb) locus of hepatocytes to produce fluorescently labeled albumin (Alb-mNG). We constructed a CRISPR AAV that includes [~]1 kb homologous arms around Alb exon 14 to express Alb-mNG. Subcutaneous injection of this AAV with AAV-CMV-Cas9 in postnatal day 3 mice resulted in two-photon visualization of the cerebral cortex vasculature within ten days. The expression levels of Alb-mNG were persistent for at least three months and were so robust that vasomotion and capillary blood flow could be assessed transcranially in early postnatal mice. This knock-in approach provides powerful means for micro- and macroscopic imaging of cerebral vascular dynamics in postnatal and adult mice.

neuroscience↗

bioRxiv2022

Dynamic Modulation of Pulsatile Activities of Oxytocin Neurons in Lactating Wild-type Mice

Breastfeeding, which is essential for the survival of mammalian infants, is critically mediated by pulsatile secretion of the pituitary hormone oxytocin from the central oxytocin neurons located in the paraventricular and supraoptic hypothalamic nuclei of mothers. Despite its importance, the molecular and neural circuit mechanisms of the milk ejection reflex remain poorly understood, in part because a mouse model to study lactation was only recently established. In our previous study, we successfully introduced fiber photometry-based chronic imaging of the pulsatile activities of oxytocin neurons during lactation. However, the necessity of Cre recombinase-based double knock-in mice substantially compromised the use of various Cre-dependent neuroscience toolkits. To overcome this obstacle, we developed a simple Cre-free method for monitoring oxytocin neurons by an adeno-associated virus vector driving GCaMP6s under a 2.6 kb mouse oxytocin mini-promoter. Using this method, we monitored calcium ion transients of oxytocin neurons in the paraventricular nucleus in wild-type C57BL/6N and ICR mothers without genetic crossing. By combining this method with video recordings of mothers and pups, we found that the pulsatile activities of oxytocin neurons require physical mother-pup contact for the milk ejection reflex. Notably, the frequencies of photometric signals were dynamically modulated by mother-pup reunions after isolation and during natural weaning stages. Collectively, the present study illuminates the temporal dynamics of pulsatile activities of oxytocin neurons in wild-type mice and provides a tool to characterize maternal oxytocin functions.

neuroscience↗

bioRxiv2022

Liver-secreted fluorescent blood plasma markers enable chronic imaging of microcirculation

Studying blood microcirculation is vital for gaining insights into vascular diseases. Acute administration of fluorescent tracers is currently used for deep tissue blood flow imaging. This is invasive, and the plasma fluorescence decreases within an hour of administration. We report a novel approach for the longitudinal study of vasculature. Using a single systemic administration of viral vectors, we express fluorescent secretory albumin-fusion proteins in the liver to label the blood in mice. All segments of the vasculature in brain and peripheral tissue are observable by two-photon microscopy within two weeks of vector administration. This approach allows for observation of circulation without the need for repeated administration for several months. We demonstrate the chronic assessment of vascular functions at micro-and mesoscopic scales. This genetic plasma labeling approach represents a versatile and cost-effective method for the chronic investigation of vasculature functions across the body in health and disease.

physiology↗

bioRxiv2021

Plasticity of Neural Connections Underlying Oxytocin-mediated Parental Behaviors of Male Mice

The adult brain can flexibly adapt behaviors to specific life-stage demands. For example, while sexually naive male mice are aggressive to the conspecific young, they start to provide caregiving to infants around the time when their own young are expected. How such behavioral plasticity is implemented at the level of neural connections remains poorly understood. Using viral-genetic approaches, here we establish hypothalamic oxytocin neurons as key regulators of parental caregiving behaviors of male mice. We then used rabies virus-mediated unbiased screen to identify excitatory neural connections originating from the lateral hypothalamus to the oxytocin neurons to be drastically strengthened when male mice become fathers. These connections are functionally relevant, as their activation suppresses pup-directed aggression in virgin males. These results demonstrate the life-stage associated, long-distance, and cell-type-specific plasticity of neural connections in the hypothalamus, the brain region classically assumed to be hard-wired. Highlight- OT is indispensable for parental caregiving behavior of male mice - Activation of OT neurons triggers paternal caregiving behavior in otherwise infanticidal sexually-naive male mice partly via OT ligand - Unbiased rabies virus-mediated screening reveals enhanced connectivity originated from excitatory LHA neurons to OT neurons in fathers. - This structural plasticity can support behavioral plasticity

neuroscience↗

bioRxiv2021

Cortical cell ensemble control of past experience-dependent memory updating

When processing current sensory inputs, animals refer to related past experiences. Current information is then incorporated into the related neural network to update previously stored memories. However, the neuronal mechanism underlying the impact of memories of prior experiences on current learning is not well understood. Here, we found that a cellular ensemble in the posterior parietal cortex (PPC) that is activated during past experience mediates an interaction between past and current information to update memory through a PPC-anterior cingulate cortex circuit in mice. Moreover, optogenetic silencing of the PPC ensemble immediately after retrieval dissociated the interaction without affecting individual memories stored in the hippocampus and amygdala. Thus, a specific subpopulation of PPC cells represents past information and instructs downstream brain regions to update previous memories.

neuroscience↗

bioRxiv2020

Mechanical impact on the head has an antihypertensive effect

Physical exercise is known to be beneficial for various brain functions. However, the mechanisms behind the positive effects of exercise on the brain remain to be elucidated. Here we show that passive head motion in hypertensive rats, which reproduces the mechanical accelerations generated in their heads during moderate-velocity treadmill running, decreases the expression of angiotensin II type 1 receptor (AT1R) in astrocytes in the rostral ventrolateral medulla (RVLM), thereby lowering blood pressure. Passive head motion generates interstitial fluid movement that is estimated to exert shear stress with an average magnitude of <1 Pa on the cells in the rat medulla. Fluid shear stress of a sub-Pa magnitude decreases AT1R expression in cultured astrocytes. In hypertensive rats, inhibition of interstitial fluid movement following hydrogel introduction to the RVLM eliminates the antihypertensive effects of passive head motion and treadmill running. Furthermore, vertically oscillating chair riding by hypertensive adult humans, which reproduces the mechanical accelerations generated in their heads during light jogging or fast walking, lowers their blood pressure. Our findings indicate that moderate mechanical intervention can have antihypertensive effects by modulating the function of RVLM astrocytes through interstitial fluid shear stress. We anticipate that mechanical regulation is responsible for a variety of the positive effects of physical exercise on human health, particularly those related to brain functions.

bioengineering↗

bioRxiv2018

Deletion of class II ARF causes essential tremors through Nav1.6 traffic impairment

ADP-ribosylation factors (ARFs) are a family of small monomeric GTPases consisting of three classes. In the present study, we generated class II ARF-deficient mice (ARF4+/-/ARF5-/-) and found that they exhibited severe movement-associated tremors. Treatment of the mice with propranolol and gabapentin, which alleviate symptoms in patients with essential tremors, similarly reduced the amplitude of the pathologic tremors. In vivo electrophysiological recordings of the ARF4+/-/ARF5-/- mice revealed that they exhibited reduced excitability of their cerebellar Purkinje cells. Immunohistochemical studies revealed that ARF4+/-/ARF5-/- mice exhibit a severe, selective reduction of Nav1.6 proteins that are important for maintaining repetitive action potential firing in the axon initial segments (AISs) of the Purkinje cells. This decrease in Nav1.6 protein expression and the consequent tremors were alleviated by Purkinje cell-specific expression of ARF5. These results indicate that class II ARF mediates the selective trafficking of Nav1.6 to the AISs in cerebellar Purkinje cells, and suggest that the essential tremors can be ascribed to the reduced intrinsic excitability of Purkinje cells, caused by the selective decrease of Nav1.6 proteins in the AISs.

neuroscience↗