La Montanara, P. | Search bioRxiv

bioRxiv2019

Cyclin-dependent-like kinase 5 is required for pain signalling in both human neurons and mouse models

Cyclin-dependent-like kinase 5 (Cdkl5) gene mutations lead to an X-linked disorder that is characterized by infantile epileptic encephalopathy, developmental delay and hypotonia. However, we found that a substantial percentage of these patients also report a previously unrecognised anamnestic deficiency in pain perception. Consistent with a role in nociception, we discovered that Cdkl5 is expressed selectively in nociceptive dorsal root ganglia (DRG) neurons in mice and in iPS-derived human nociceptors. CDKL5 deficient mice display defective epidermal innervation and conditional deletion of Cdkl5 in DRG sensory neurons significantly impairs nociception, phenocopying CDKL5 deficiency disorder in patients. Mechanistically, Cdkl5 interacts with CaMKII to control outgrowth as well as TRPV1-dependent signalling, which are disrupted in both Cdkl5 mutant murine DRG and human iPS-derived nociceptors. Together, these findings unveil a previously unrecognized role for Cdkl5 in nociception, proposing an original regulatory mechanism for pain perception with implications for future therapeutics in CDKL5 deficiency disorder.\n\nOne Sentence SummaryCyclin-dependent-like kinase 5 (Cdkl5) controls nociception in patients and murine models of Cdkl5 deficiency disorder via CaMKII-dependent mechanisms

neuroscience↗

bioRxiv2019

Combinatorial proteomics and transcriptomics identify AMPK in the control of the axonal regeneration programme of DRG sensory neurons after spinal injury

Regeneration after injury occurs in axons that lie in the peripheral nervous system but it fails in the central nervous system limiting functional recovery. Despite recent progress, the signalling response to injury of peripheral versus central projecting axons that might underpin this differential regenerative ability is currently largely uncharacterized. To fill this knowledge gap, here we combined axoplasmic proteomics from peripheral sciatic or central projecting dorsal root axons from sciatic DRG neurons. Proteomics was combined with cell body RNAseq to compare axonal and soma responses between a spinal regeneration-incompetent versus sciatic regeneration-competent nerve injury. This allowed the identification of injury-dependent signalling pathways uniquely represented in peripheral versus central projecting sciatic DRG axons. RNAseq and proteomics analysis suggested AMPK as a putative regulator of axonal regenerative signalling pathways. AMPK immunoprecipitation followed by mass spectrometry from DRG suggested that the 26S proteasome and its regulatory subunit PSMC5 preferentially interact with AMPK for proteasomal degradation following sciatic axotomy. Mechanistically, we found that the proteasome and CaMKII-dependent proteasomal subunit PSMC5 regulates AMPK1 protein expression. Finally, conditional deletion of AMPK1 promoted multiple regenerative signalling pathways and robust axonal growth across the injured spinal cord, suggesting inhibition of AMPK as a novel regenerative target following spinal injury.\n\nHIGHLIGHTSO_LIAxoplasmic proteomics from sciatic or centrally projecting branches of sciatic DRG identifies unique protein enrichment and signalling pathways, including prior and subsequent to a spinal regeneration-incompetent versus sciatic regeneration-competent axonal injury\nC_LIO_LICombined axoplasmic DRG proteomics and cell body RNAseq analysis suggest AMPK as a central regulator controlling axonal regeneration\nC_LIO_LIThe 26S proteasome and the 19S regulatory subunit PSMC5 interact with AMPK following sciatic axotomy. PSMC5 regulates AMPK1 protein levels\nC_LIO_LIAMPK1 conditional deletion enhances robust axonal growth following SCI\nC_LI

neuroscience↗