Chick Lrrn2, a novel downstream effector of Hoxb1 and Shh, functions in the selective targeting of rhombomere 4 motor neurons

<p>Abstract</p> <p>Background</p> <p>Capricious is a <it>Drosophila </it>adhesion molecule that regulates specific targeting of a subset of motor neurons to their muscle target. We set out to identify whether one of its vertebrate homologues, Lrrn2, might play an analogous role in the chick.</p> <p>Results</p> <p>We have shown that <it>Lrrn2 </it>is expressed from early development in the prospective rhombomere 4 (r4) of the chick hindbrain. Subsequently, its expression in the hindbrain becomes restricted to a specific group of motor neurons, the branchiomotor neurons of r4, and their pre-muscle target, the second branchial arch (BA2), along with other sites outside the hindbrain. Misexpression of the signalling molecule Sonic hedgehog (Shh) via <it>in ovo </it>electroporation results in upregulation of <it>Lrrn2 </it>exclusively in r4, while the combined expression of Hoxb1 and Shh is sufficient to induce ectopic <it>Lrrn2 </it>in r1/2. Misexpression of Lrrn2 in r2/3 results in axonal rerouting from the r2 exit point to the r4 exit point and BA2, suggesting a direct role in motor axon guidance.</p> <p>Conclusion</p> <p>Lrrn2 acts downstream of Hoxb1 and plays a role in the selective targeting of r4 motor neurons to BA2.</p

Analysis of Lrrn1 expression and its relationship to neuromeric boundaries during chick neural development

<p>Abstract</p> <p>Background</p> <p>The <it>Drosophila </it>leucine-rich repeat proteins Tartan (TRN) and Capricious (CAPS) mediate cell affinity differences during compartition of the wing imaginal disc. This study aims to identify and characterize the expression of a chick orthologue of TRN/CAPS and examine its potential function in relation to compartment boundaries in the vertebrate central nervous system.</p> <p>Results</p> <p>We identified a complementary DNA clone encoding Leucine-rich repeat neuronal 1 (Lrrn1), a single-pass transmembrane protein with 12 extracellular leucine-rich repeats most closely related to TRN/CAPS. <it>Lrrn1 </it>is dynamically expressed during chick development, being initially localized to the neural plate and tube, where it is restricted to the ventricular layer. It becomes downregulated in boundaries following their formation. In the mid-diencephalon, <it>Lrrn1 </it>expression prefigures the position of the anterior boundary of the zona limitans intrathalamica (ZLI). It becomes progressively downregulated from the presumptive ZLI just before the onset of expression of the signalling molecule Sonic hedgehog (Shh) within the ZLI. In the hindbrain, downregulation at rhombomere boundaries correlates with the emergence of specialized boundary cell populations, in which it is subsequently reactivated. Immunocolocalization studies confirm that Lrrn1 protein is endocytosed from the plasma membrane and is a component of the endosomal system, being concentrated within the early endosomal compartment.</p> <p>Conclusion</p> <p>Chick Lrrn1 is expressed in ventricular layer neuroepithelial cells and is downregulated at boundary regions, where neurogenesis is known to be delayed, or inhibited. The timing of <it>Lrrn1 </it>downregulation correlates closely with the activation of signaling molecule expression at these boundaries. This expression is consistent with the emergence of secondary organizer properties at boundaries and its endosomal localisation suggests that Lrrn1 may regulate the subcellular localisation of specific components of signalling or cell-cell recognition pathways in neuroepithelial cells.</p

The Scaffolding Function of LSD1 Controls DNA Methylation in Mouse ESCs

Lysine-specific histone demethylase 1 (LSD1), which demethylates mono- or di- methylated histone H3 on lysine 4 (H3K4me1/2), is essential for early embryogenesis and development. Here we show that LSD1 is dispensable for mouse embryonic stem cell (ESC) self-renewal but is required for mouse ESC growth and differentiation. Reintroduction of a catalytically-impaired LSD1 (LSD1MUT) recovers the proliferation capability of mouse ESCs, yet the enzymatic activity of LSD1 is essential to ensure proper differentiation. Indeed, increased H3K4me1 in Lsd1 knockout (KO) mouse ESCs does not lead to major changes in global gene expression programs related to stemness. However, ablation of LSD1 but not LSD1MUT results in decreased DNMT1 and UHRF1 proteins coupled to global hypomethylation. We show that both LSD1 and LSD1MUT control protein stability of UHRF1 and DNMT1 through interaction with HDAC1 and the ubiquitin-specific peptidase 7 (USP7), consequently, facilitating the deacetylation and deubiquitination of DNMT1 and UHRF1. Our studies elucidate a mechanism by which LSD1 controls DNA methylation in mouse ESCs, independently of its lysine demethylase activity

DNA Editing for Amyotrophic Lateral Sclerosis : Leading Off First Base

Gene therapy in a mouse model for amyotrophic lateral sclerosis (ALS) illustrates the rapid deployment of base editing in therapeutic modeling of neurodegenerative disease

Role of pannexin-1 in the cellular uptake, release and hydrolysis of anandamide by T84 colon cancer cells

The large pore ion channel pannexin-1 (Panx1) has been reported to play a role in the cellular uptake and release of anandamide (AEA) in the hippocampus. It is not known whether this is a general mechanism or limited to the hippocampus. We have investigated this pharmacologically using T84 colon cancer cells. The cells expressed Panx1 at the mRNA level, and released ATP in a manner that could be reduced by treatment with the Panx1 inhibitors carbenoxolone and mefloquine and the Panxl substrate SR101. However, no significant effects of these compounds upon the uptake or hydrolysis of exogenously applied AEA was seen. Uptake by T84 cells of the other main endocannabinoid 2-arachidonoylglycerol and the AEA homologue palmitoylethanolamide was similarly not affected by carbenoxolone or mefloquine. Total release of tritium from [H-3]AEA-prelabelled T84 cells over 10 min was increased, rather than inhibited by carbenoxolone and mefloquine. Finally, AEA uptake by PC3 prostate cancer and SH-SY5Y neuroblastoma cells, which express functional Panx1 channels, was not inhibited by carbenoxolone. Thus, in contrast to the hippocampus, Panx1 does not appear to play a role in AEA uptake and release from the cells studied under the conditions used

Historia y trajes de las ordenes religiosas

3 t. en 2 vol.Menció d'ed.: vol. 2: Librería Española y Estrangera, Agencia Médica--Catalana; vol. 3: Agencia Médica Catalan

Additional file 2: of Cell-type- and region-specific restriction of neurotropic flavivirus infection by viperin

Figure S2. Viperin is highly upregulated in astrocytes after TBEV infection, and it inhibits LGTV infection in cortical astrocytes and neurons. Primary cortical neurons and cortical astrocytes were isolated and differentiated from WT mice and infected with TBEV (MOI, 0.1). (A) Viperin expression was measured by qPCR at the indicated time points. Viperin mRNA was normalized to the GAPDH expression and represented as dCt. Primary WT and viperin−/− astrocytes (B) and cortical neurons (C) were infected with LGTV (MOI, 0.1), and viral growth was determined at indicated time points by focus-forming assay. Statistical significance was calculated using unpaired t test, significance is indicated by asterisks (**P < 0.01, ***P < 0.001). Data are cumulative from at least two independent experiments performed in triplicates. (PDF 541 kb

CAM-Delam: an in vivo approach to visualize and quantify the delamination and invasion capacity of human cancer cells

The development of metastases is the major cause of cancer related death. To develop a standardized method that define the ability of human cancer cells to degrade the basement membrane, e.g. the delamination capacity, is of importance to assess metastatic aggressiveness. We now present the in vivo CAM-Delam assay to visualize and quantify the ability of human cancer cells to delaminate and invade. The method includes seeding cancer cells on the chick chorioallantoic membrane (CAM), followed by the evaluation of cancer-induced delamination and potential invasion within hours to a few days. By testing a range of human cancer cell lines in the CAM-Delam assay, our results show that the delamination capacity can be divided into four categories and used to quantify metastatic aggressiveness. Our results emphasize the usefulness of this assay for quantifying delamination capacity as a measurement of metastatic aggressiveness, and in unraveling the molecular mechanisms that regulate delamination, invasion, formation of micro-metastases and modulations of the tumor microenvironment. This method will be useful in both the preclinical and clinical characterization of tumor biopsies, and in the validation of compounds that may improve survival in metastatic cancer