Biology subjects

Deuchars, J.

Publications and source records attributed to Deuchars, J..

4 recordsLinked to original sources

bioRxiv2020

LncRNAs interacting with the translation machinery contribute to human neuronal differentiation.

LncRNAs are less conserved, yet more tissue and developmental-stage specific than mRNAs and are particularly enriched in the nervous system of Drosophila melanogaster, mouse and human. The function of cytoplasmic lncRNAs and their potential translation remains poorly understood. Here we performed Poly-Ribo-Seq to understand the interaction of lncRNAs with the translation machinery and the functional consequences during neuronal differentiation of SH-SH5Y cells. We discovered 237 cytoplasmic lncRNAs upregulated during early neuronal differentiation, most of which are associated with polysome complexes. The majority are cytoplasmically enriched and are intergenic or anti-sense. In addition, we find 45 small ORFs in lncRNAs to be actively translated, 17 specifically upon differentiation. 11 of these smORFs exhibit high sequence conservation across Hominidae suggesting they are under strong selective constraint with putative function in this clade. We discover LINC01116 is induced upon differentiation and contains an 87 codon smORF, which we detect as translated, with increased ribosome profiling signal upon differentiation. The LINC01116 peptide exhibits a cytoplasmic distribution and is detected in neurites. Knockdown of LINC01116 results in significant reduction of neurite length in differentiated cells indicating it contributes to neuronal differentiation. Our findings indicate lncRNAs are a source of non-canonical peptides and contribute to neuronal function.

molecular biology↗

bioRxiv2020

Graded calcium spikes differentially signal neurotransmitter input in cerebrospinal fluid contacting neurons of mouse spinal cord

The action potential and its all-or-none nature is fundamental to neural communication. Canonically the action potential is initiated once voltage-gated Na+ channels are activated, and their rapid kinetics of activation and inactivation give rise to the action potentials all-or-none nature. Here we show that cerebrospinal fluid contacting neurons (CSFcNs) surrounding the central canal of the mouse spinal cord employ a different strategy. Rather than using voltage-gated Na+ channels to generate binary spikes, CSFcNs use two different types of voltage-gated Ca2+ channel, enabling spikes of different amplitude. T-type Ca2+ channels generate small amplitude spikes, whereas large amplitude spikes require high voltage-activated Cd2+ sensitive Ca2+ channels. We show that these different amplitude spikes signal input from different transmitter systems; purinergic inputs evoke smaller T-type dependent spikes while cholinergic inputs evoke large T-type independent spikes. Different synaptic inputs to CSFcNs can therefore be signalled by the spike amplitude.

neuroscience↗

bioRxiv2020

Inhibition of Mitochondrial Fission and iNOS in the Dorsal Vagal Complex Protects from Overeating and Weight Gain

The dorsal vagal complex (DVC) senses changes in insulin levels and controls glucose homeostasis, feeding behaviour and body weight. Three days of high-fat diet (HFD) in rats is sufficient to induce insulin resistance in the DVC and impair its ability to regulate feeding behaviour. HFD-feeding is associated with increased mitochondrial fission in the DVC and fission is regulated by dynamin-related protein 1 (Drp1). Higher Drp1 activity can inhibit insulin signalling, although the exact mechanisms controlling body weight remain elusive. Here we show that Drp1 activation in DVC leads to higher body weight in rats and Drp1 inhibition in HFD-fed rats reduced body weight gain, cumulative food intake and adipose tissue, and prevented insulin resistance. Rats expressing active Drp1 in the DVC had higher levels of inducible nitric oxide synthase (iNOS) and knockdown of iNOS in the DVC of HFD-fed rats led to a reduction in body weight gain, cumulative food intake and adipose tissue, and prevented insulin resistance. In obese insulin-resistant animals, inhibition of mitochondrial fission or DVC iNOS knockdown restored insulin sensitivity and decreased food intake, body weight and fat deposition. Finally, we show that inhibiting mitochondrial fission in DVC astrocytes is sufficient to protect rats from developing HFD-dependent insulin resistance, hyperphagia, body weight gain and fat deposition. Our study uncovers new molecular and cellular targets for brain regulation of whole-body metabolism, which could inform new strategies to combat obesity and diabetes.

neuroscience↗

bioRxiv2020

Piggybacking on the Cholera Toxin: Identification of a Toxoid-binding Protein as an Approach for Targeted Delivery of Proteins to Motor Neurons

A significant unmet need exists for the delivery of biologic drugs such as polypeptides or nucleic acids, to the central nervous system (CNS) for the treatment and understanding of neurodegenerative diseases. Naturally occurring toxoids have been considered as tools to meet this need. However, due to the complexity of tethering macromolecular drugs to toxins, and the inherent dangers of working with large quantities of recombinant toxin, no such route has been successfully exploited. Developing a method where toxoid and drug can be assembled immediately prior to in vivo administration has the potential to circumvent some of these issues. Using a phage-display screen, we identified two antibody mimetics, Anti-Cholera Toxoid Affimer (ACTA) -A2 and ACTA-C6 that non-covalently associate with the non-binding face of the cholera toxin B-subunit. In a first step toward the development of a non-viral motor neuron drug-delivery vehicle, we show that Affimers can be selectively delivered to motor neurons in vivo.

biochemistry↗