Profile of MicroRNAs following Rat Sciatic Nerve Injury by Deep Sequencing: Implication for Mechanisms of Nerve Regeneration

Unlike the central nervous system, peripheral nerves can regenerate when damaged. MicroRNA (miRNA) is a novel class of small, non-coding RNA that regulates gene expression at the post-transcriptional level. Here, we report regular alterations of miRNA expression following rat sciatic nerve injury using deep sequencing. We harvested dorsal root ganglia tissues and the proximal stumps of the nerve, and identified 201 and 225 known miRNAs with significant expression variance at five time points in these tissues after sciatic nerve transaction, respectively. Subsequently, hierarchical clustering, miRNA expression pattern and co-expression network were performed. We screened out specific miRNAs and further obtained the intersection genes through target analysis software (Targetscan and miRanda). Moreover, GO and KEGG enrichment analyses of these intersection genes were performed. The bioinformatics analysis indicated that the potential targets for these miRNAs were involved in nerve regeneration, including neurogenesis, neuron differentiation, vesicle-mediated transport, homophilic cell adhesion and negative regulation of programmed cell death that were known to play important roles in regulating nerve repair. Finally, we combined differentially expressed mRNA with the predicted targets for selecting inverse miRNA-target pairs. Our results show that the abnormal expression of miRNA may contribute to illustrate the molecular mechanisms of nerve regeneration and that miRNAs are potential targets for therapeutic interventions and may enhance intrinsic regenerative ability

Early and reversible changes to the hippocampal proteome in mice on a high-fat diet

Funding LMW, FMC, CG, ACM and C-DM were funded by the Scottish Government’s Rural and Environment Science and Analytical Services Division (RESAS). FHM was supported by an EASTBIO DTP BBSRC studentship. DS was supported by a SULSA studentship.Peer reviewedPublisher PD

Importin α3 regulates chronic pain pathways in peripheral sensory neurons

How is neuropathic pain regulated in peripheral sensory neurons? Importins are key regulators of nucleocytoplasmic transport. In this study, we found that importin α3 (also known as karyopherin subunit alpha 4) can control pain responsiveness in peripheral sensory neurons in mice. Importin α3 knockout or sensory neuron-specific knockdown in mice reduced responsiveness to diverse noxious stimuli and increased tolerance to neuropathic pain. Importin α3-bound c-Fos and importin α3-deficient neurons were impaired in c-Fos nuclear import. Knockdown or dominant-negative inhibition of c-Fos or c-Jun in sensory neurons reduced neuropathic pain. In silico screens identified drugs that mimic importin α3 deficiency. These drugs attenuated neuropathic pain and reduced c-Fos nuclear localization. Thus, perturbing c-Fos nuclear import by importin α3 in peripheral neurons can promote analgesia

Axonal transcription factors signal retrogradely in lesioned peripheral nerve

Retrograde axonal injury signalling stimulates cell body responses in lesioned peripheral neurons. The involvement of importins in retrograde transport suggests that transcription factors (TFs) might be directly involved in axonal injury signalling. Here, we show that multiple TFs are found in axons and associate with dynein in axoplasm from injured nerve. Biochemical and functional validation for one TF family establishes that axonal STAT3 is locally translated and activated upon injury, and is transported retrogradely with dynein and importin alpha5 to modulate survival of peripheral sensory neurons after injury. Hence, retrograde transport of TFs from axonal lesion sites provides a direct link between axon and nucleus