Project description:Peripheral sensory neurons regenerate their axons after injury to regain function, but this ability declines with age. The mechanisms behind this decline are not fully understood. While excessive production of endothelin 1 (ET-1), a potent vasoconstrictor, is linked to many diseases that increase with age, the role of ET-1 and its receptors in axon regeneration is unknown. Using single cell RNA sequencing, we show that satellite glial cells (SGCs), which completely envelop the sensory neuron soma residing in the dorsal root ganglia (DRG), express the endothelin B receptor (ETBR), while ET-1 is expressed by endothelial cells. Inhibition of ETBR ex-vivo in DRG explant cultures improves axon growth in both adult and aged conditions. In vivo, treatment with the FDA-approved compound, Bosentan, improves axon regeneration and reverses the age-dependent decrease in axonal regenerative capacity. Single-nuclei RNA sequencing and electron microscopy analyses reveal a decreased abundance of SGCs in aged mice compared to adult mice. Additionally, the decreased expression of connexin 43 (Cx43) in SGCs in aged mice after nerve injury is partially rescued by Bosentan treatment. These results reveal that inhibiting ETBR function enhances axon regeneration and rescues the age-dependent decrease in axonal regenerative capacity, providing a potential avenue for future therapies.
Project description:Peripheral sensory neurons regenerate their axons after injury to regain function, but this ability declines with age. The mechanisms behind this decline are not fully understood. While excessive production of endothelin 1 (ET-1), a potent vasoconstrictor, is linked to many diseases that increase with age, the role of ET-1 and its receptors in axon regeneration is unknown. Using single cell RNA sequencing, we show that satellite glial cells (SGCs), which completely envelop the sensory neuron soma residing in the dorsal root ganglia (DRG), express the endothelin B receptor (ETBR), while ET-1 is expressed by endothelial cells. Inhibition of ETBR ex-vivo in DRG explant cultures improves axon growth in both adult and aged conditions. In vivo, treatment with the FDA-approved compound, Bosentan, improves axon regeneration and reverses the age-dependent decrease in axonal regenerative capacity. Single-nuclei RNA sequencing and electron microscopy analyses reveal a decreased abundance of SGCs in aged mice compared to adult mice. Additionally, the decreased expression of connexin 43 (Cx43) in SGCs in aged mice after nerve injury is partially rescued by Bosentan treatment. These results reveal that inhibiting ETBR function enhances axon regeneration and rescues the age-dependent decrease in axonal regenerative capacity, providing a potential avenue for future therapies.
Project description:Irreversible blindness from glaucoma and optic neuropathies is attributed to retinal ganglion cells (RGCs) losing the ability to regenerate axons. While several transcription factors and proteins have demonstrated enhancement of axon regeneration after optic nerve injury, mechanisms contributing to the age-related decline in axon regenerative capacity remains elusive. Here, we show that microRNAs are differentially expressed during RGC development, and identify microRNA-19a (miR-19a) as a heterochronic marker; developmental decline of miR-19a relieves suppression of PTEN, a key regulator of axon regeneration, and serves as a temporal indicator of decreasing axon regenerative capacity. Intravitreal injection of miR-19a promotes axon regeneration after optic nerve crush in adult mice, and increases axon extension in RGCs isolated from aged human donors. This uncovers a previously unrecognized involvement of the miR-19a-PTEN axis in RGC axon regeneration, and demonstrates therapeutic potential of microRNA-mediated restoration of axon regenerative capacity via intravitreal injection in patients with optic neuropathies.
Project description:Time resolved phosphorylation changes were measured the melanoma cell lines A2058 and UACC257. An endothelin B receptor knockout of UACC257 was processed in parallel. Protein abundance was also compared at the latest time point of the study (90 min) using DIA-SWATH
Project description:In this project, we isolate U1 snRNA associated proteins in Arabidopsis thaliana. We used an antisense oligonucleotide specific for the U1 snRNA and analyzed associated proteins by mass spectrometry. As a control, the same experiments were performed with U2 snRNA- and lacZ-specifc antisense oligonucleotides.
Project description:Endothelin signaling is one of the essential signaling pathways that control vertebrate development. Dysregulated Endothelin signaling plays an important role in the pathogenesis of human diseases such as Hirschsprung’s disease, pulmonary hypertension and cancer. However, the downstream transcriptional program and transcriptional factors of Endothelin signaling have been incompletely understood. Here, we used RNA-sequencing to identify the genes regulated by Endothelin signaling in the neural crest, where Endothelin signaling functions primarily during development. We further demonstrate that Endothelin induces gene expression through the de-repression of the MADS Box transcription factor MEF2C. Moreover, in the Mef2c gene locus, we identified an Endothelin responsive cis-regulatory element which functions as a central component of an Endothelin-MEF2C positive feedback transcriptional mechanism that regulates downstream gene expression.
Project description:Spliceosomal snRNA are key components of small nuclear ribonucleoprotein particles (snRNPs), the building blocks of the spliceosome. The biogenesis of snRNPs is a complex process involving multiple cellular and subcellular compartments, the details of which are yet to be described. In short, the snRNA is exported to the cytoplasm as 3‘-end extended precursor (pre-snRNA), where it acquires a heptameric Sm ring. The SMN complex which catalyses this step, recruits Sm proteins and assembles them around the pre-snRNA at the single stranded Sm site. After additional modification, the complex is re-imported into the nucleus where the final maturation step occurs. Our modeling suggests that during the cytoplasmic stage of maturation pre-snRNA assumes a compact secondary structure containing Near Sm site Stem (NSS) which is not compattible with the formation of the Sm ring. To validate our in silico predictions we employed selective 2'-hydroxyl acylation analyzed by primer extension sequencing (SHAPE-Seq) on U2 snRNA in vivo, ex vivo and in vitro, and U4 pre-snRNA in vitro. For the in vivo experiment HeLa cells were incubated for 10 min at 37°C with NAI or DMSO to final concentration 200 mM. RNA was isolated using Trizol (Sigma) and 200 µl chloroform and precipitated with ethanol at -20°C overnight. For the ex vivo experiment, RNA was isolated from HeLa cells after Protease K treatment at room temperature for 45 min. After incubation, RNA was isolated using equilibrated phenol/chloroform/isoamyl alcohol buffered by folding buffer (110 mM HEPES pH 8.0, 110 mM KCl, 11 mM MgCl2) and cleaned on a PD-10 column according to the manufacturer’s instructions. Isolated RNA was treated with 100mM NAI or DMSO for 10 min at 37°C. For the in vitro experiment, U2WT and U4 pre-snRNA were transcribed by T7 polymerase followed by DNase I (30 min at 37 °C) and Proteinase K (30 min at 37°C) treatments. U2 snRNA was purified on 30 kDa Amicon columns, folded for 30 min at 37°C in 57 mM MgCl2 and incubated with 100 mM NAI at 37°C for 10 min. DMSO was used as a negative control. U4 pre-snRNA was purified on Superdex 200 Increase 10/300GL, folded for 30 min at 37°C in 60 mM MgCl2 and incubated with 100 mM NAI at 37°C for 10 min. DMSO was used as a negative control. All prepared RNA samples (in vitro, ex vivo, in vivo) were used for reverse transcription with the gene-specific primer 5’-CGTTCCTGGAGGTACTGCAA for U2 snRNA and 5’- AAAAATTCAGTCTCCG for U4 pre-snRNA. We used SHAPE MaP buffer (50 mM Tris-HCl pH 8.0, 75 mM KCl, 10 mM DTT, 0.5 mM dNTP, 6 mM MnCl2) and SuperScript II (Invitrogen). Amplicons for snRNAs were generated using gene-specific forward and reverse primers. Importantly, the primers include Nextera adaptors required for downstream library construction. PCR reaction products were cleaned using Monarch PCR&DNA Clean-up Kits. Remaining Illumina adaptor sequences were added using the PCR MasterMix and index primers provided in the NexteraXT DNA Library Preparation Kit (Illumina) according to the manufacturer’s protocol. Libraries were quantified using Qubit (Invitrogen) and BioAnalyzer (Agilent). Amplicons were sequenced on a NextSeq 500/550 platform using a 150 cycle mid-output kit. All sequencing data was analyzed using the ShapeMapper 2 analysis pipeline1. The ‘—amplicon’ and ‘—primers’ flags were used, along with sequences of gene-specific handles PCR primers, to ensure primer binding sites are excluded from reactivity calculations. Default read-depth thresholds of 5000x were used. Analysis of statistically significant reactivity differences between ex vivo and in vivo-determined SHAPE reactivities was performed using the DeltaSHAPE automated analysis tool and default settings2. 1. Busan, S. & Weeks, K.M. Accurate detection of chemical modifications in RNA by mutational profiling (MaP) with ShapeMapper 2. RNA 24, 143-148 (2018). 2. Smola, M.J., Rice, G.M., Busan, S., Siegfried, N.A. & Weeks, K.M. Selective 2'-hydroxyl acylation analyzed by primer extension and mutational profiling (SHAPE-MaP) for direct, versatile and accurate RNA structure analysis. Nat Protoc 10, 1643-69 (2015).