Biology subjects

Colameo, D.

Publications and source records attributed to Colameo, D..

5 recordsLinked to original sources

bioRxiv2026

Isogenic forebrain organoids uncover early neurodevelopmental alterations and imbalances in neuronal function leading to hyperexcitation in Gaucher disease

Gaucher disease is a rare lysosomal storage disorder caused by autosomal recessive mutations in the GBA1 gene, encoding the lysosomal enzyme glucocerebrosidase. Gaucher disease is classified in 3 different subtypes depending on the presence and severity of neurological involvement, with type 2 resulting in fatal early-onset neuropathology and patients exhibiting developmental delays, seizures and early death. Studies investigating disease mechanisms of neuronopathic Gaucher disease are mainly based on animal models and focus predominantly on late neuronal phenotypes. Here, we established healthy control and Gaucher disease patient-derived iPSC lines and engineered them to obtain isogenic control and disease lines. Using these lines, we generated cortical and subpallial brain organoids in which we identified early-onset lipid dysregulation in form of glucosylceramide accumulation, highly elevated glucosylsphingosine, and a later increase in ganglioside levels, recapitulating clinical findings. Furthermore, single-cell transcriptomic profiling uncovered novel phenotypes in both cortical and subpallial forebrain organoids. Subpallial alterations consisted of an early increase in migrating interneurons in subpallial organoids, which upregulated cholesterol metabolism. Cortical alterations showed early upregulation of mitochondrial genes and a downregulation of proliferation, with a subsequent switch from GABAergic to glutamatergic neuron fate with a striking increase in gene expression related to the synaptic assembly. Functional assays demonstrated a marked hyperexcitability of cortical organoids and reduced response to GABA-A receptor blockage in Gaucher disease. Additional 2D neuronal network models confirmed the organoid data and showed that both glutamatergic and GABAergic neurons contribute to the phenotype, with hyperexcitability of Gaucher glutamatergic neurons and incapacity of Gaucher GABAergic neurons to balance the excessive excitation. This alteration represents a clinically significant phenotype as many patients exhibit an excitation/inhibition imbalance leading to treatment-resistant seizures, hastening their decline. In conclusion, our defined human models of Gaucher disease identify novel and clear phenotypes that can be used for drug screening or aid in development of new therapeutic strategies to ameliorate Gaucher disease.

neuroscience↗

bioRxiv2023

microRNA-218-5p Coordinates Scaling of Excitatory and Inhibitory Synapses during Homeostatic Synaptic Plasticity

Homeostatic synaptic plasticity (HSP) is a fundamental neuronal mechanism that allows networks to compensate for prolonged changes in activity by adjusting synaptic strength. This process is crucial for maintaining stable brain function and has been implicated in memory consolidation during sleep. While scaling of both excitatory and inhibitory synapses plays an important role during homeostatic synaptic plasticity, molecules coordinating both of these processes are unknown. In this study, we investigate the role of miR-218-5p as a regulator of inhibitory and excitatory synapses in the context of picrotoxin (PTX)-induced homeostatic synaptic downscaling (HSD) in rat hippocampal neurons. Using enrichment analysis of miRNA-binding sites in differentially expressed genes changing upon PTX-induced HSD, we bioinformatically predicted and experimentally validated increased miR-218-5p activity upon PTX-treatment in the process compartment. By monitoring synapse structure in vitro with confocal microscopy, we demonstrate that inhibiting miR-218-5p activity exerts a dual effect during HSD: it prevents the downscaling of excitatory synapses and dendritic spines, while at the same time blocking inhibitory synapse upscaling. Furthermore, we identify the Neuroligin2 interacting molecule Mdga1 as a crucial target of miR-218-5p in the context of homeostatic upscaling of inhibitory synapses. By performing long-term electroencephalographic (EEG) recordings, we further revealed that local inhibition of miR-218-5p in the somatosensory cortex reduced local slow-wave activity (SWA) during non-rapid-eye-movement (NREM) sleep. In summary, this study uncovers miR-218-5p as a key player in coordinating inhibitory and excitatory synapses during homeostatic plasticity and sleep. Our findings contribute to a deeper understanding of how neural circuits maintain stability in the face of activity-induced perturbations, with potential implications for both physiological and pathological conditions. Significance StatementHomeostatic synaptic plasticity mechanisms evolved to keep neuronal firing rates within a physiological range in response to alterations in neural network activity. It has been proposed that similar mechanisms take place during sleep in a process that promotes memory consolidation and synaptic renormalization. In this study, posttranscriptional regulation of synaptic proteins by miR-218-5p has been identified to coordinate both excitatory and inhibitory synaptic scaling during activity-dependent homeostatic synaptic plasticity. Intriguingly, local inhibition of miR-218-5p in the cortex of mice resulted in reduced slow-wave activity, an EEG-signature of synchronous firing during non-rapid eye movement sleep and a hallmark correlate of sleep pressure. Overall, these findings propose a convergent, posttranscriptional mechanism to coordinate both excitatory and inhibitory synaptic strength in response to alterations in neuronal activity with potential implications for sleep.

neuroscience↗

bioRxiv2023

A human-specific microRNA controls the timing of excitatory synaptogenesis

Neural circuit development in the human cortex is considerably prolonged in comparison to non-human primates, a trait that contributes to the remarkable cognitive capacity of modern humans. Here, we explore the regulatory role of non-coding RNAs, which dramatically expanded during brain evolution, in synapse development of human-induced pluripotent stem-cell derived neurons. We found that inhibition of a human-specific microRNA, miR-1229-3p, alters the trajectory of human neuronal maturation and enhances excitatory synaptic transmission. Transcriptome analysis following miR-1229 knockdown revealed a downregulation of mitochondrial DNA (mtDNA) encoded genes. We further show that miR-1229 regulates mitochondrial morphology, mtDNA abundance and matrix calcium concentration, and that stimulation of mitochondrial metabolism rescues decreased calcium buffering in miR-1229-3p depleted neurons. Accordingly, miR-1229 directly targets an entire network of genes involved in mitochondrial function and ER-associated protein homeostasis. Our findings reveal an important function of human-specific miR-1229-3p in developmental timing of human synaptogenesis and generally implicate non-coding RNAs in the control of human connectivity and cognition. One-Sentence SummaryA human-specific microRNA slows down the formation and maturation of neuronal synapses by reducing mitochondrial metabolism.

neuroscience↗

bioRxiv2022

miR-329 and miR-495-mediated Prr7 downregulation isrequired for homeostatic synaptic depression in rathippocampal neurons

Homeostatic synaptic depression (HSD) in excitatory neurons is a cell autonomous mechanism which protects excitatory neurons from over-excitation as a consequence of chronic increases in network activity. In this process, excitatory synapses are weakened and eventually eliminated, as evidenced by a reduction in synaptic AMPA receptor expression and dendritic spine loss. Originally considered a global, cell-wide mechanism, local forms of regulation, such as the local control of mRNA translation in dendrites, are being increasingly recognized in HSD. Yet, identification of excitatory proteins whose local regulation is required for HSD is still limited. Here, we show that Proline-rich protein 7/Transmembrane Adapter Protein 3 (Prr7) downregulation in dendrites of rat hippocampal neurons is necessary for HSD induced by chronic increase in network activity resulting from a blockade of inhibitory synaptic transmission by picrotoxin (PTX). We further identify two activity-regulated miRNAs, miR-329-3p and miR-495-3p, which inhibit Prr7 mRNA translation and are required for HSD. Moreover, we found that Prr7 knockdown reduces expression of the synaptic scaffolding protein SPAR, which is rescued by pharmacological inhibition of CDK5, indicating a role of Prr7 protein in the maintenance of excitatory synapses via protection of SPAR from degradation. Together, our findings highlight a novel HSD mechanism in which chronic activity leads to miR-329 and miR-495-mediated local Prr7 reduction upstream of the CDK5-SPAR pathway.

neuroscience↗

bioRxiv2020

Pervasive compartment-specific regulation of gene expression during homeostatic synaptic scaling

Synaptic scaling is a form of homeostatic plasticity which allows neurons to adjust their action potential firing rate in response to chronic alterations in neural activity. Synaptic scaling requires profound changes in gene expression, but the relative contribution of local and cell-wide mechanisms is controversial. Here we performed a comprehensive multi-omics characterization of the somatic and process compartments of primary rat hippocampal neurons during synaptic scaling. Thereby, we uncovered both highly compartment-specific and correlated changes in the neuronal transcriptome and proteome. Whereas downregulation of crucial regulators of neuronal excitability occurred primarily in the somatic compartment, structural components of excitatory postsynapses were mostly downregulated in processes. Motif analysis further suggests an important role for trans-acting post-transcriptional regulators, including RNA-binding proteins and microRNAs, in the local regulation of the corresponding mRNAs. Altogether, our study indicates that compartmentalized gene expression changes are widespread in synaptic scaling and might co-exist with neuron-wide mechanisms to allow synaptic computation and homeostasis.

neuroscience↗