Biology subjects

Strano, A.

Publications and source records attributed to Strano, A..

5 recordsLinked to original sources

bioRxiv2024

Altered neuronal network activity and connectivity in human Down Syndrome excitatory cortical neurons

Down syndrome (DS) is the most common genetic cause of intellectual disability, affecting one in 700 live births worldwide, and is caused by trisomy of the human chromosome 21 (Hsa21), yet the cellular and molecular mechanisms driving neuronal network dysfunction remain poorly understood. Here, we investigated whether trisomy 21 (TS21) alters the spontaneous synchronised activity of excitatory neuron networks, potentially contributing to the neurodevelopmental phenotypes of DS. By modelling human cortical development in vitro with TS21 and matched control human iPSCs from two DS donors, we investigated the impact of Hsa21 triplication on neural network activity and connectivity. Calcium imaging revealed an early and pronounced reduction in neuronal activity in TS21 cortical neurons, including a marked loss of synchronised bursting. These deficits persisted up to 80 days in vitro and for over 5 months in vivo following transplantation into the mouse forebrain, as shown by multiphoton calcium imaging through a cranial window. Viral trans-synaptic tracing identified significant reduction of neuronal connectivity in TS21 neuronal networks in vitro, suggesting that reduced network connectivity contributes to the dramatic reduction of synchronised bursting. Furthermore, TS21 neurons displayed significantly reduced expression of voltage-gated potassium channels, with single-neuron recordings confirming a reduction of hyperpolarization-activated currents. Together, these findings demonstrate long-lasting impairments in human cortical excitatory neuron network function associated with Trisomy 21.

neuroscience↗

bioRxiv2021

Effects of Hydroxychloroquine and Azithromycin on iPSC-derived Cardiomyocytes: Considerations for the Treatment of COVID-19 Patients

Despite known adverse effects of hydroxychloroquine (HCQ) and azithromycin (AZM) on cardiac function, HCQ and AZM have been used as combination therapy in the treatment of COVID-19 patients. Recent clinical data indicate higher complication rates with HCQ/AZM combination treatment in comparison to monotherapy. Here, we used human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) to systematically investigate the effects of HCQ and AZM individually and in combination. The clinically observed QT prolongation caused by treatment with HCQ could be recapitulated in iPSC-CMs based on prolonged field potential duration (FPDc). Interestingly, HCQ-induced FPDc prolongation was strongly enhanced by combined treatment with AZM, although AZM alone slightly shortened FPDc in iPSC-CMs. Furthermore, combined treatment with AZM and HCQ leads to higher cardiotoxicity, more severe structural disarrangement, and more pronounced contractile and electrophysiological dysfunctions, compared to respective mono-treatments. First mechanistic insights underlying the synergistic effects of AZM and HCQ on iPSC-CM functionality are provided based on increased Cx43- and Nav1.5-protein levels. Taken together, our results highlight that combined treatment with HCQ and AZM strongly enhances the adverse effects on cardiomyocytes, providing mechanistic evidence for the high mortality in patients receiving HCQ/AZM combination treatment.

pharmacology and toxicology↗

bioRxiv2020

Whole genome CRISPR screens identify LRRK2-regulated endocytosis as a major mechanism for extracellular tau uptake by human neurons

Extracellular release and cellular uptake of pathogenic forms of the microtubule-associated protein tau contribute to the pathogenesis of several neurodegenerative diseases, including Alzheimers disease. Defining the cellular mechanisms and pathways for tau entry to human neurons is essential to understanding tauopathy pathogenesis and the rational design of disease-modifying therapeutics. Whole genome CRISPR loss-of-function screens in human iPSC-derived excitatory neurons, the major neuronal cell type affected in these diseases, enabled the delineation of the different cellular pathways for uptake of extracellular monomeric and fibrillar tau. Monomeric and fibrillar tau are both taken up by human neurons by receptor-mediated endocytosis, but involve different routes of entry at the neuronal surface: the low-density lipoprotein LRP1 is the primary receptor for monomeric tau, but contributes less to fibrillar tau entry. Similarly, endocytosis of monomeric tau is dependent on the familial Parkinsons disease gene LRRK2, but not required for endocytosis of fibrillar tau. These findings implicate LRP1 and LRRK2 in the pathogenesis of tauopathies and Parkinsons disease and identify LRRK2 as a potential therapeutic target for altering progression of these diseases.

neuroscience↗

bioRxiv2020

Molecular and cellular pathology of monogenic Alzheimer's disease at single cell resolution

Cell and molecular biology analyses of sporadic Alzheimers disease brain are confounded by clinical variability, ageing and genetic heterogeneity. Therefore, we used single-nucleus RNA sequencing to characterize cell composition and gene expression in the cerebral cortex in early-onset, monogenic Alzheimers disease. Constructing a cellular atlas of frontal cortex from 8 monogenic AD individuals and 8 matched controls, provided insights into which neurons degenerate in AD and responses of different cell types to AD at the cellular and systems level. Such responses are a combination of positively adaptive and deleterious changes, including large-scale changes in synaptic transmission and marked metabolic reprogramming in neurons. The nature and scale of the transcriptional changes in AD emphasizes the global impact of the disease across all brain cell types. One Sentence SummaryAlzheimers disease brain atlas provides insights into disease mechanisms

neuroscience↗

bioRxiv2020

BAcTrace a new tool for retrograde tracing of neuronal circuits

New tools and techniques have enabled many key advances in our understanding of the brain. To elucidate circuit function, it is necessary to identify, record from and manipulate networks of connected neurons. Here we present BAcTrace (Botulinum Activated Tracer), the first fully genetically encoded, retrograde, transsynaptic labelling system. BAcTrace is based on C. botulinum neurotoxin A, Botox, which we have engineered to act as a Trojan horse that jumps retrogradely between neurons to activate an otherwise silent transcription factor. We validate BAcTrace at three connections in the Drosophila olfactory system and show that it enables electrophysiological recordings of connected neurons. Finally, in a challenging circuit with highly divergent connections, we used Electron Microscopy connectomics to show that BAcTrace correctly identifies 12 out of 16 connections.

neuroscience↗