Role of TGF-β Activated Kinase 1(TAK1) in Chick Retinal Development

poster abstractBone morphogenetic proteins (BMPs) play a critical role in vertebrate eye development by regulating cell fate processes in the retina through canonical SMAD and non-canonical MAPK pathways. TGF-β Activated Kinase 1(TAK1) is a MAPKKK that activates the MAPK cascade upon BMP activation. Dysregulation of TAK1 is associated with a variety of diseased states including cancer, but little is known about the role of TAK1 in development. Recent in vitro studies have indicated that TAK1 inhibits the G1-S phase Cyclin D, a process known to be critical to cell cycle exit. Although no studies have focused on the role of TAK1 in retinal development, many studies have indicated that BMPs as well as properly timed cell cycle exit are critical for the differentiation of specific cell types. In studies designed to test the hypothesis that TAK1 is an essential regulator of cell cycle exit in the chick embryonic retina, we have performed immunohistochemistry using an antibody that specifically detects the activated form of TAK1 (pTAK1) and shown the extensive localization of pTAK1 in a subset of differentiated cells and, more prominently, in the mitotic progenitor cells of the retina. Our preliminary studies, aimed at in vivo pharmacological inhibition of TAK1 activity using (5Z)-7-Oxozeaenol in the developing chick eye, show that TAK1 inhibition could lead to a range of developmental defects in the retina. While further studies focusing on molecular changes resulting from TAK1 inhibition and overexpression would shed more light on its functional role in the retina, our results suggest that TAK1 signaling is critical for normal eye development. The heavy localization of pTAK1 in mitotic progenitor cells especially, could be indicative of its role in cell cycle exit. Understanding the functional role of this protein in the context of eye development could aid in understanding the pathophysiology of diseased states associated with TAK1

Role of TGF-β activated kinase 1 (TAK1) in chick retinal development

Cell cycle exit and concomitant commitment to a differentiated cell fate are critical processes that require an intricate communication between intrinsic guides within the cell and extrinsic cues from the environment. As the focal points of various signaling pathways, the mitogen activated protein kinases (MAPK) are the crossroads at which a multitude of extrinsic signals converge and are relayed to the cell. TGF-β activated kinase 1 (TAK1), a MAP3K known to be activated downstream of BMP and TGF-β signaling, is increasingly being implicated in control of proliferation and differentiation in many cell types. Clues to its mechanism come from in vitro studies that have shown TAK1 to inhibit a G1-S phase cyclin D1, a protein critical to progression of cell cycle. As such, TAK1 has the potential to act as an intermediary that translates extrinsic cues to intrinsic cell fate decisions in the retina. Using the embryonic chick as a model for vertebrate retinal development, we have performed immunohistochemistry using an antibody that specifically detects the activated form of TAK1 (pTAK1). This has revealed, for the first time, the extensive localization of pTAK1 in a subset of differentiated cells and more prominently, in the mitotic progenitor cells of the retina. Our preliminary studies aimed at in vivo pharmacological inhibition of TAK1 activity, using (5Z)-7-Oxozeaenol, in the developing chick eye, show that TAK1 inhibition down-regulates the JNK MAPK pathway while resulting in an increase in progenitor cell population, paralleled by a decrease in differentiated cell types. The nuclear localization of both active and inactive TAK1 is a novel finding of this study that contrasts the known cytoplasmic localization and might suggest unique roles for TAK1 in retinal cells. This is the first study to show that TAK1 signaling is active during retinal development and potentially regulates exit of retinal progenitors from the cell cycle

Liposomal delivery of ferritin heavy chain 1 (FTH1) siRNA in patient xenograft derived glioblastoma initiating cells suggests different sensitivities to radiation and distinct survival mechanisms.

Elevated expression of the iron regulatory protein, ferritin heavy chain 1 (FTH1), is increasingly being associated with high tumor grade and poor survival outcomes in glioblastoma. Glioma initiating cells (GICs), a small population of stem-like cells implicated in therapeutic resistance and glioblastoma recurrence, have recently been shown to exhibit increased FTH1 expression. We previously demonstrated that FTH1 knockdown enhanced therapeutic sensitivity in an astrocytoma cell line. Therefore, in this study we developed a liposomal formulation to enable the in vitro delivery of FTH1 siRNA in patient xenograft derived GICs from glioblastomas with pro-neural and mesenchymal transcriptional signatures to interrogate the effect of FTH1 downregulation on their radiation sensitivity. Transfection with siRNA decreased FTH1 expression significantly in both GICs. However, there were inherent differences in transfectability between pro-neural and mesenchymal tumor derived GICs, leading us to modify siRNA: liposome ratios for comparable transfection. Moreover, loss of FTH1 expression resulted in increased extracellular lactate dehydrogenase activity, executioner caspase 3/7 induction, substantial mitochondrial damage, diminished mitochondrial mass and reduced cell viability. However, only GICs from pro-neural glioblastoma showed marked increase in radiosensitivity upon FTH1 downregulation demonstrated by decreased cell viability, impaired DNA repair and reduced colony formation subsequent to radiation. In addition, the stemness marker Nestin was downregulated upon FTH1 silencing only in GICs of pro-neural but not mesenchymal origin. Using liposomes as a siRNA delivery system, we established FTH1 as a critical factor for survival in both GIC subtypes as well as a regulator of radioresistance and stemness in pro-neural tumor derived GICs. Our study provides further evidence to support the role of FTH1 as a promising target in glioblastoma

L'Avenir de Luchon : journal scientifique, littéraire, annonces et réclames : guide général des baigneurs et des touristes aux eaux thermales, bains de mer de la France et de l'étranger

28 avril 19291929/04/28 (N437)-1929/04/28.Appartient à l’ensemble documentaire : MidiPyren

Immunohistochemistry for Ki-67 expression on the sciatic nerves from the tumor induced and control (untreated) mice indicates that the IL13Rα2 staining pattern was intense in tumor tissue.

<p>Immunohistochemistry for Ki-67 expression on the sciatic nerves from the tumor induced and control (untreated) mice indicates that the IL13Rα2 staining pattern was intense in tumor tissue.</p

Immunohistochemistry for Ki-67 expression on the sciatic nerves from the tumor induced and control (untreated) mice indicates that the IL13Rα2 staining pattern was intense in tumor tissue.

<p>Immunohistochemistry for Ki-67 expression on the sciatic nerves from the tumor induced and control (untreated) mice indicates that the IL13Rα2 staining pattern was intense in tumor tissue.</p

Fluorescent microscopic images of sNF96.2 and ST88-14 MPNST cells after exposure to IL13LIPDXR for 2 hours, followed by immunocytochemistry for IL13Rα2.

<p>The green color in the cytoplasmic region represents the expression of IL13Rα2 receptor and the red color represents the endogenous fluorescence of the internalized doxorubicin delivered through targeted liposomes. (B) IL13LIPDXR is also able to bind and internalize through multicellular spheroids after exposure for 2 hours as evidenced by confocal microscopy images. More details can be found in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181529#pone.0181529.s002" target="_blank">S2 Fig</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0181529#pone.0181529.s004" target="_blank">S1 Video</a>.</p

IL13Rα2 expression in the sciatic nerve tumor developed in NIHIII mice injected with sNF96.2 NF-1 cells.

<p>The expression levels were compared with the control sciatic nerves which were not injected with the cells.</p

Serum chemistry analysis.

<p>The analysis was performed 48 hours post injection of the 7mg/kg dose of targeted and non-targeted liposomal doxorubicin. The values were compared with control mice injected with phosphate buffered saline. The levels indicate that liver functional enzymes including bilirubin and alkaline phosphatase are comparable in both the treated and control groups of mice. Creatinine and BUN levels are also comparable to that of untreated control mice, indicating that renal function is not significantly affected due to treatment.</p

IL13Rα2 expression in various tissues from a peripheral nerve carcinoma tissue microarray.

<p>Representative microscopic images from the tissue microarray after IHC for IL13Rα2 expression are shown (panel A-F). Malignant Schwannoma distinctly shows robust expression of IL13Rα2 in the tissue (D) with positive expression in benign neurofibromas as evident from the IHC (E,F). Normal nerve tissue indicated minimal staining without distinct cellular morphology. No IL13Rα2 staining was observed in cancer adjacent normal tissues.</p