Biology subjects

Waldron, S.

Publications and source records attributed to Waldron, S..

6 recordsLinked to original sources

bioRxiv2026

Intracellular amino acid scarcity sensing tunes protein hunger

Protein is a key macronutrient that strongly governs food intake. Following dietary protein scarcity, animals display compensatory preference for amino acid-rich food, yet how the brain detects and encodes protein hunger remains unclear. To address this question, we used Drosophila melanogaster to investigate the function of peptidergic neurons, a major neuromodulatory cell population that includes key regulators of feeding behaviour and protein homeostasis. We present a high-resolution transcriptional atlas obtained by RNA sequencing of single peptidergic nuclei isolated from the brains of sated and amino acid deprived flies. Consistent with a resource-sparing response, differential expression analysis revealed widespread transcriptional downregulation in the amino acid deprived state. A screen of differently expressed candidates identified Lsp2, a gene encoding an amino acid storage protein, as a regulator of protein intake. Knock down and overexpression experiments demonstrate that Lsp2 levels act as a gauge in a specific population of peptidergic neurons expressing Myoinhibiting peptide precursor (Mip) to modulate protein appetite. We further show that compensatory protein feeding following amino acid deprivation depends on maintaining Mip+ neuron activity within an appropriate range. Our findings reveal that peptidergic neurons can directly sense intracellular protein deficiency and use this information to guide protein intake. By linking amino acid storage to the neuronal control of feeding, this work establishes a foundation for understanding how protein needs are encoded in the brain.

neuroscience↗

bioRxiv2026

Antisense Oligonucleotides Targeting an LDLR Regulatory RNA Increase LDLR Expression and Reduce LDL-cholesterol in Vivo

Regulatory RNAs (regRNAs) are non-coding RNAs expressed from promoters and enhancers that modulate gene transcription. Targeting regRNAs with antisense oligonucleotides (ASOs) can increase transcription and presents a potential therapeutic strategy to restore expression in haploinsufficient diseases. This approach requires high-quality regRNA maps, identification of ASOs targeting actionable sequences, and translation of efficacy to relevant animal models. Here, we describe this approach for human low-density lipoprotein receptor (LDLR). We characterized LDLR regRNAs in HepG2 cells and human liver using epigenomic mapping and regRNA Capture-seq, and designed ASOs targeting these regRNAs. Several ASOs increased LDLR expression in cells and a lead was evaluated for efficacy in a humanized liver mouse model. ASO administration increased human LDLR mRNA and protein, while lowering LDL-cholesterol in plasma. These data provide a framework for the discovery and translation of ASOs that increase gene expression as a potential therapeutic approach for the treatment of haploinsufficient diseases.

molecular biology↗

bioRxiv2026

Profiling and Targeting of Regulatory RNAs to Upregulate Gene Expression

Transcription of long noncoding RNAs (lncRNAs), including enhancer RNAs (eRNAs) and promoter-associated RNAs (paRNAs), collectively termed regulatory RNAs (regRNAs), is a hallmark of active gene expression, yet it remains unknown whether regRNAs can be targeted to selectively enhance transcription in cis. We developed regRNA Capture-seq, a high-throughput method to profile regRNAs, and applied it to primary human hepatocytes, annotating thousands of regRNAs at [~]2,000 enhancers and promoters. Using this approach, we interrogated a genetically validated enhancer of the ornithine transcarbamylase (OTC) gene, mutations of which cause OTC deficiency (OTCD), the most common urea cycle disorder. Antisense oligonucleotides (ASOs) targeting enhancer-derived regRNAs led to dose-dependent upregulation of OTC in hepatocytes. Mechanistically, ASOs altered regRNA structure, elevated regRNA levels, displaced transcriptional repressors, and increased H3K27 acetylation at the targeted enhancer. This work establishes a potential therapeutic strategy for addressing haploinsufficiency and highlights regRNAs as actionable targets for ASO-mediated upregulation of gene expression.

genomics↗

bioRxiv2023

Linked OXTR Variants Are Associated with Social Behavior Differences in Bonobos (Pan paniscus)

Single-nucleotide polymorphisms (SNPs) in forkhead box protein P2 (FOXP2), oxytocin receptor (OXTR), and arginine vasopressin receptor gene 1A (AVPR1A) have been associated with linguistic and social development in humans, as well as symptom severity in autism. Studying biobehavioral mechanisms in the species most closely related to humans can provide insights into the origins of human communication, and the impact of genetic variation on complex behavioral phenotypes. Here, we tested the hypothesis that similar genetic factors underlie social communication differences in both bonobos (Pan paniscus) and humans. We analyzed Sanger sequencing results to determine if bonobos exhibit individual variation at 10 loci across FOXP2, OXTR, and AVPR1A that have been implicated in human social development and behavior. We identified a novel variant in bonobo FOXP2, as well as three novel variants in bonobo OXTR that were 19-184 base pairs away from the target human SNPs. We also found a linked SNP combination (TGA) across the 3 novel bonobo OXTR sites at high frequency (65%) in the study population, including 6 homozygous bonobos. When comparing the combined OXTR genotypes, we found significant group differences in social behavior; bonobos with two copies of the TGA combination were more social than bonobos with one copy and bonobos with zero copies of the TGA combination. Taken together, our findings suggest that these OXTR variants may influence individual-level social behavior in bonobos and support the notion that linked genetic variants are promising biomarkers for differences in human social communication. Revision SummaryThe original manuscript version underwent peer-review at Frontiers in Behavioral Neuroscience. As a part of this process, a reviewer requested that the sequence files be included in the manuscript. While preparing these files, Dr. Hudson identified several errors in his work regarding the individual bonobo genotypes reported in the original version of the manuscript. Upon discovery of the errors, Dr. Skiba and Dr. Taglialatela conducted a new genetic analysis using the raw files and subsequently corrected the misreported information - updating the editorial team and including the raw sequences with the revised manuscript. In addition to requested edits for improvement and clarity by the peer-reviewers, this revised manuscript corrects several errors in the human and bonobo reference genomes, the SNP locations, and the individual genotypes reported in the original manuscript. Information in the figures, main text, and supplementary materials has been corrected in this revised version. Dr. Hudson and his lab member, Mr. Hansen, were unable to identify how the errors in data reporting occurred, and neither party contributed to the revised version of this manuscript. The co-author list has been adjusted to reflect contributions to the corrected analyses and revised manuscript. We are deeply grateful to the editorial team and reviewers at Frontiers in Behavioral Neuroscience for their thorough peer-review of this work - improving the overall quality of the manuscript and leading to the discovery and correction of substantial errors in the original version.

evolutionary biology↗

bioRxiv2021

Behavioural and molecular characterisation of the Dlg2 haploinsufficiency rat model of genetic risk for psychiatric disorder

Genetic studies implicate disruption to the DLG2 gene in copy number variants as increasing risk for schizophrenia, autism spectrum disorders and intellectual disability. To investigate psychiatric endophenotypes associated with DLG2 haploinsufficiency (and concomitant PSD-93 protein reduction) a novel clinically relevant Dlg2+/- rat was assessed for abnormalities in anxiety, sensorimotor gating, hedonic reactions, social behaviour, and locomotor response to the N-Methyl-D-aspartic acid receptor antagonist phencyclidine. Dlg gene and protein expression were also investigated to assess model validity. Reductions in PSD-93 messenger RNA and protein were observed in the absence of compensation by other related genes or proteins. Behaviourally Dlg2+/- rats show potentiated locomotor response to phencyclidine, as is typical of psychotic disorder models, in the absence of deficits in the other behavioural phenotypes assessed here. This shows that the behavioural effects of Dlg2 haploinsufficiency may specifically relate to psychosis vulnerability but are subtle, providing a contrast to the gross deficits in Dlg2 homozygous models (Winkler, et al., 2018; Yoo et al., 2020a) which do not so specifically model the single chromosome DLG2 deletion in carriers of risk-associated copy number variants.

genetics↗

bioRxiv2021

Reduced expression of the psychiatric risk gene DLG2 (PSD93) impairs hippocampal synaptic integration and plasticity

Background: Genetic variations indicating loss of function in the DLG2 gene have been associated with markedly increased risk for schizophrenia, autism spectrum disorder, and intellectual disability. DLG2 encodes the postsynaptic scaffolding protein DLG2 (PSD93) that interacts with NMDA receptors, potassium channels, and cytoskeletal regulators but the net impact of these interactions on synaptic plasticity, likely underpinning cognitive impairments associated with these conditions, remains unclear. Methods: Hippocampal CA1 neuronal excitability and synaptic function were investigated in a novel clinically relevant heterozygous Dlg2+/- rat model using ex vivo patch-clamp electrophysiology, pharmacology, and computational modelling. Results: Dlg2+/- rats had increased NMDA receptor-mediated synaptic currents and, conversely, impaired associative long-term potentiation. This impairment resulted from an increase in potassium channel function leading to a decrease in input resistance and reduced supra-linear dendritic integration during induction of associative long-term potentiation. Enhancement of dendritic excitability by blockade of potassium channels or activation of muscarinic M1 receptors with selective allosteric agonist 77-LH-28-1 reduced the threshold for dendritic integration and 77-LH-28-1 rescued the associative long-term potentiation impairment in the Dlg2+/- rats. Conclusions: Despite increasing synaptic NMDA receptor currents, the combined impact of reduced DLG2 impairs synaptic integration in dendrites resulting in disrupted associative synaptic plasticity. This biological phenotype can be reversed by compound classes used clinically such as muscarinic M1 receptor agonists and is therefore a potential target for therapeutic intervention.

neuroscience↗