Biology subjects

Nishiyama, N.

Publications and source records attributed to Nishiyama, N..

3 recordsLinked to original sources

bioRxiv2026

Sequentially Self-Assembled Supramolecular Nanocomplexes Enable Systemic Cas9 RNP Delivery and In Vivo Tumor Genome Editing

In vivo genome editing with CRISPR-Cas9 ribonucleoproteins (RNPs) holds substantial therapeutic promise, yet rapid bloodstream clearance and the absence of delivery systems capable of systemic tumor targeting have hindered its clinical translation. Herein, a supramolecular ternary complex platform is reported in which Cas9/sgRNA RNPs are co-assembled with tannic acid (TA) and phenylboronic acid (PBA)-conjugated polymers through sequential self-assembly, producing [~]30 nm core-shell ternary complexes that protect RNPs from enzymatic degradation and dissociate selectively at endosomal pH. Upon intravenous administration in subcutaneous tumor-bearing mice, these ternary complexes exhibit prolonged blood circulation and preferential tumor accumulation, achieving 37.2% gene editing at tumor sites compared with only 1.5% for free RNPs. The platform successfully knocks out previously undruggable oncogenes including mutant KRAS and polo-like kinase 1 (PLK1), markedly suppressing tumor growth in vivo. By integrating sequential supramolecular self-assembly with stimuli-responsive cargo release, this strategy establishes a generalizable framework for systemically administered in vivo CRISPR therapeutics.

bioengineering↗

bioRxiv2023

Loss of Purkinje cells in the developing cerebellum strengthens the cerebellothalamic synapses

Cerebellar damage early in life often causes long-lasting motor, social, and cognitive impairments, suggesting the roles of the cerebellum in developing a broad spectrum of behaviors. This recent finding has promoted research on how cerebellar damage affects the development of the cerebral cortex, the brain region responsible for higher-order control of all behaviors. However, the cerebral cortex is not directly connected to the cerebellum. The thalamus is the direct postsynaptic target of the cerebellum, sending cerebellar outputs to the cerebral cortex. Despite its crucial position in cerebello-cerebral interaction, thalamic susceptibility to cerebellar damage remains largely unclear. Here, we studied the consequences of early cerebellar perturbation on thalamic development. Whole-cell patch-clamp recordings showed that the synaptic organization of the cerebellothlamic circuit is similar to that of the primary sensory thalamus, in which aberrant sensory activity alters synaptic circuit formation. The hemizygous deletion of the tuberous sclerosis complex-1 (Tsc1) gene in the Purkinje cell--known to cause Purkinje cell hypoactivity and autistic behaviors--did not alter cerebellothalamic synapses or intrinsic membrane properties of thalamic neurons. However, the ablation of Purkinje cells in the developing cerebellum strengthened the cerebellothalamic synapses and enhanced thalamic suprathreshold activities. These results suggest that the cerebellothalamic circuit is resistant to moderate perturbation in the developing cerebellum, such as the reduced firing rate of Purkinje cells, and that autistic behaviors are not necessarily linked to thalamic abnormality. Still, Purkinje cell loss alters the thalamic circuit, suggesting the vulnerability of the thalamus to substantial disturbance in the developing cerebellum.

neuroscience↗

bioRxiv2020

Frequency switching between oscillatory homeostats and the regulation of p53

Homeostasis is an essential concept to understand the stability of organisms and their adaptive behaviors when coping with external and internal assaults. Many hormones that take part in homeostatic control come in antagonistic pairs, such as glucagon and insulin reflecting the inflow and outflow compensatory mechanisms to control a certain internal variable, such as blood sugar levels. By including negative feedback loops homeostatic controllers can exhibit oscillations with characteristic frequencies. In this paper we demonstrate the associated frequency changes in homeostatic systems when individual controllers in a set of interlocked feedback loops gain control in response to environmental changes. Taking p53 as an example, we show how the Per2, ATM and Mdm2 feedback loops -interlocked with p53-gain individual control in dependence to DNA damage and how each of these controllers provide certain functionalities in their regulation of p53. In unstressed cells, the circadian regulator Per2 ensures a basic p53 level to allow its rapid up-regulation in case of DNA damage. When DNA damage occurs the ATM controller increases the level of p53 and defends it towards uncontrolled degradation, which despite DNA damage, would drive p53 to lower values and p53 dysfunction. Mdm2 on its side keeps p53 at a maximum level to avoid premature apoptosis. However, with on-going DNA damage the Mdm2 set-point is increased by HSP90 and other p53 stabilizers leading finally to apoptosis. An essential aspect in p53 regulation at occurring cell stress is the coordinated inhibition of ubiquitin-independent and ubiquitin-dependent degradation reactions and the increasing stabilizing mechanisms of p53. Whether oscillations serve a function or are merely a by-product of the controllers are discussed in view of the finding that homeostatic control of p53, as indicated above, does in principle not require oscillatory homeostats.

systems biology↗