Non-functional ubiquitin C-terminal hydrolase L1 drives podocyte injury through impairing proteasomes in autoimmune glomerulonephritis

In membranous nephropathy autoantibodies target podocytes of the kidney filter resulting in injury. Here the authors show that the ensuing proteostatic disturbances and proteinuria relate to aberrant interactions of non-functional UCH-L1 enzyme with the proteasome, curtailing its capacity.Little is known about the mechanistic significance of the ubiquitin proteasome system (UPS) in a kidney autoimmune environment. In membranous nephropathy (MN), autoantibodies target podocytes of the glomerular filter resulting in proteinuria. Converging biochemical, structural, mouse pathomechanistic, and clinical information we report that the deubiquitinase Ubiquitin C-terminal hydrolase L1 (UCH-L1) is induced by oxidative stress in podocytes and is directly involved in proteasome substrate accumulation. Mechanistically, this toxic gain-of-function is mediated by non-functional UCH-L1, which interacts with and thereby impairs proteasomes. In experimental MN, UCH-L1 becomes non-functional and MN patients with poor outcome exhibit autoantibodies with preferential reactivity to non-functional UCH-L1. Podocyte-specific deletion of UCH-L1 protects from experimental MN, whereas overexpression of non-functional UCH-L1 impairs podocyte proteostasis and drives injury in mice. In conclusion, the UPS is pathomechanistically linked to podocyte disease by aberrant proteasomal interactions of non-functional UCH-L1.Bio-organic Synthesi

Identification of molecular signatures specific for distinct cranial sensory ganglia in the developing chick

Background The cranial sensory ganglia represent populations of neurons with distinct functions, or sensory modalities. The production of individual ganglia from distinct neurogenic placodes with different developmental pathways provides a powerful model to investigate the acquisition of specific sensory modalities. To date there is a limited range of gene markers available to examine the molecular pathways underlying this process. Results Transcriptional profiles were generated for populations of differentiated neurons purified from distinct cranial sensory ganglia using microdissection in embryonic chicken followed by FAC-sorting and RNAseq. Whole transcriptome analysis confirmed the division into somato- versus viscerosensory neurons, with additional evidence for subdivision of the somatic class into general and special somatosensory neurons. Cross-comparison of distinct ganglia transcriptomes identified a total of 134 markers, 113 of which are novel, which can be used to distinguish trigeminal, vestibulo-acoustic and epibranchial neuronal populations. In situ hybridisation analysis provided validation for 20/26 tested markers, and showed related expression in the target region of the hindbrain in many cases. Results One hundred thirty-four high-confidence markers have been identified for placode-derived cranial sensory ganglia which can now be used to address the acquisition of specific cranial sensory modalities.</p

ARD: Die cDNA fuer ein neuronales, entwicklungsspezifisch reguliertes Polypeptid des nikotinischen Acetylcholinrezeptors von Drosophila

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Expression of the KCl cotransporter KCC2 parallels neuronal maturation and the emergence of low intracellular chloride

Fast synaptic inhibition in the adult central nervous system (CNS) is mediated by GABA and glycine. During early development GABA acts as an excitatory neurotransmitter, which is deemed to be important for the maturation of the CNS. During development GABAergic responses undergo a switch from excitatory to inhibitory. This switch is correlated with upregulation of KCC2, the neuronal isoform of the potassium-chloride cotransporter family. KCC2 lowers the intraneuronal chloride concentration below its electrochemical equilibrium. KCC2 activity is thought to depend on phosphorylation by endogenous tyrosine kinases. Here, we analyzed the expression pattern of KCC2 during murine embryonic and postnatal development by in situ hybridization and Western blot analysis. KCC2 expression paralleled neuronal differentiation and preceded the decline of the GABA reversal potential (EGABA) in spinal cord motoneurons and hippocampal pyramidal cells. The adult inhibitory response to GABA was established earlier in the spinal cord than in the hippocampus. Phosphorylated KCC2 protein was already present early in development when the functional GABA switch had not yet occurred. Thus, tyrosine-phosphorylation seems to be less important than the transcriptional upregulation of KCC2

Disruption of KCC2 reveals an essential role of K-Cl cotransport already in early synaptic inhibition

Synaptic inhibition by GABA(A) and glycine receptors, which are ligand-gated anion channels, depends on the electrochemical potential for chloride. Several potassium-chloride cotransporters can lower the intracellular chloride concentration [Cl(-)](i), including the neuronal isoform KCC2. We show that KCC2 knockout mice died immediately after birth due to severe motor deficits that also abolished respiration. Sciatic nerve recordings revealed abnormal spontaneous electrical activity and altered spinal cord responses to peripheral electrical stimuli. In the spinal cord of wild-type animals, the KCC2 protein was found at inhibitory synapses. Patch-clamp measurements of embryonic day 18.5 spinal cord motoneurons demonstrated an excitatory GABA and glycine action in the absence, but not in the presence, of KCC2, revealing a crucial role of KCC2 for synaptic inhibition

Desert Hedgehog Links Transcription Factor Sox10 to Perineurial Development

Schwann cells are the main glial cell type in the PNS. They develop along nerves during embryogenesis and rely on the HMG domain containing Sox10 transcription factor for specification, lineage progression, and terminal differentiation. Sox10 deletion in immature Schwann cells caused peripheral nerve defects in mice that were not restricted to this glial cell type, although expression in the nerve and gene loss were. Formation of the perineurium as the protecting sheath was, for instance, heavily compromised. This resembled the defect observed after loss of Desert hedgehog (Dhh) in mice. Here we show that Sox10 activates Dhh expression in Schwann cells via an enhancer that is located in intron 1 of the Dhh gene. Sox10 binds this enhancer in monomeric form via several sites. Mutation of these sites abolishes both Schwann-cell-specific activity and Sox10 responsiveness in vitro and in transgenic mouse embryos. This argues that Sox10 activates Dhh expression by direct binding to the enhancer and by increasing Dhh levels promotes formation of the perineurial sheath. This represents the first mechanism for a non-cell-autonomous function of Sox10 during peripheral nerve development