Project description:We previously identified that the RNA binding protein Nucleolin is localized to axons of DRG sensory neurons by interaction with the molecular motor Kinesin-1 (Kif5A) and subsequently localizes importin beta1 mRNA there (Perry et al., 2016). To further identify additional RNAs that are localized to axons in a similar mechanism, we immunopercipitated Kif5A from dorsal roots (centrally projecting axons) or Sciatic nerves (peripherally projecting axons), isolated the bound RNA and sequnced it.
Project description:We previously showed that the RNA binding protein Nucleolin is localized to axons of DRG sensory neurons by interaction with the molecular motor Kinesin-1 (Kif5A) and subsequently localizes importin beta1 mRNA there (Perry et al., 2016). In this work, we created a mouse with a heterozygous deletion of the domain in nucleolin responsible for the Kif5A interaction and showed that nucelolin protein levels are reduced in the axons of dorsal root ganglia neurons in this mouse model. The goal of this study was to identify RNAs who's axonal localization is affected by this perturbation.
Project description:Damage to and/or loss of sensory neurons can result in debilitating neuropathies that often have a dramatic impact on quality of life. The cellular mechanisms involved in the response of neurons and glia to such pathological insults are poorly understood. Investigation has shown that peripheral glia play critical roles in both the degenerative and regenerative processes that are involved in the responses to peripheral nerve damage. The vast majority of studies have focused primarily on myelinating Schwann cells], with the result that very little is known regarding how the non-myelinating glia that ensheath axons and neuronal somas respond to nerve damage. This is a significant knowledge gap, given that over 80% of cutaneous fibers are unmyelinated, that they transduce such important modalities as itch, pain, temperature, touch and pressure, and that they are affected in many prevalent peripheral neuropathies. It is the goal of this study to shed light on the genetic programs involved in the responses of non-myelinating glia roles to nerve degeneration. We utilized RNA-seq to identify genes that were differentially expressed in the larval head during the process of sensory neuron ablation and axon degeneration in both wild-type larvae and in larvae that do not have peripheral glia (foxd3 mutants) using a selective, conditional approach. Overall, the information regarding differential gene expression in these conditions will provide a basis for further investigation into the cellular processes that underlie pathophysiological responses of neurons and glia to sensory nerve damage.
Project description:Mice lacking the POU-domain transcription factor Brn3a exhibit marked defects in sensory axon growth and abnormal sensory apoptosis. We have determined the regulatory targets of Brn3a in the developing trigeminal ganglion using microarray analysis of Brn3a mutant mice. These results show that Brn3 mediates the coordinated expression of neurotransmitter systems, ion channels, structural components of axons and inter- and intracellular signaling systems. Loss of Brn3a also results in the ectopic expression of transcription factors normally detected in earlier developmental stages and in other areas of the nervous system. Target gene expression is normal in heterozygous mice, consistent with prior work showing that autoregulation by Brn3a results in gene dosage compensation. Detailed examination of the expression of several of these downstream genes reveals that the regulatory role of Brn3a in the trigeminal ganglion appears to be conserved in more posterior sensory ganglia but not in the CNS neurons that express this factor. Experiment Overall Design: Microarrays used to compare the patterns of gene expression in the trigeminal ganglia of Brn3a knockout and wild-type mice. Embryonic day 13.5 (E13.5) was chosen because at this point in development mutant mice exhibit major defects in sensory axon growth, but have yet to undergo the period of extensive sensory neuron death associated with later stages.
Project description:Spinal motor axons traverse large distances to innervate target muscle, and thus require local control of cellular events for proper functioning of the distal axon. To interrogate axon-specific processes we developed Axon-seq, a refined method incorporating microfluidic devices and stringent bioinformatic quality controls. Axon-seq demonstrates improved sensitivity and accuracy in whole-transcriptome sequencing of axons compared to previously published studies. Importantly, we show that axon transcriptomes are distinct from those of somas, displaying fewer detected genes and no contaminating astrocytic markers. We identified >5,000 transcripts in stem cell-derived spinal motor axons required for local oxidative energy production and ribosome generation. Axons contained unique transcription factor mRNAs, e.g. Ybx1, with implications for local axonal functions. Cross-comparison with existing mouse motor axon datasets, as well as our own human motor axon data identified a common axon transcriptome. As motor axons degenerate in amyotrophic lateral sclerosis (ALS), we investigated their response to the disease-causing SOD1G93A mutation, identifying 121 ALS-dysregulated transcripts. Several of these are implicated in axonal and dendritic outgrowth, including Nrp1, Dbn1, and Nek1, a known ALS-causing gene. In conclusion, Axon-seq proves a robust and improved method for RNA-seq of axons, furthers our understanding of peripheral axon biology, and identifies novel therapeutic targets to maintain neural connectivity in disease.
Project description:Our objective was to evaluate the gene expression changes occuring in early sensory neuron development that were lost in the absence of Tmem184b and restored upon its reintroduction into mutant neurons in culture.
Project description:Integration of nutritional, microbial and inflammatory events along the gut-brain axis can alter bowel physiology and organism behaviour. The principal neural unit in the bowel encoding these stimuli is the visceral sensory neuron with endings at the mucosa, intramurally and along mesenteric blood vessels. Sensory neurons activate reflex pathways and give rise to conscious sensation, however, the diversity and division of function within these neurons is poorly understood. The identification of signalling pathways contributing to visceral sensation is constrained by the current paucity of molecular markers. Here we overcome these limitations by comprehensive transcriptomic profiling and unsupervised clustering of single colonic sensory neurons revealing 7 classes characterised from both lumbar splanchnic (LSN) and pelvic nerves (PN). We identify and classify neurons based on novel marker genes, confirm translation of patterning to protein expression and show subtype-selective differential agonist activation, describing sensory diversity encompassing all modalities of colonic neuronal sensitivity.