Studies on the regulation of glucose transport in thyroid cells

El presente trabajo de tesis tuvo por objetivo principal estudiar la regulación del transporte de glucosa en células tiroideas. Se utilizó un análogo no metabolizable de la glucosa, la 2-deoxiglucosa, a fin de determinar la actividad de transporte de glucosa en la línea celular FRTL-5. Se encontró que tanto la insulina como la TSH estimulan el transporte, y que juntas a 72 horas tienen un efecto sinérgico, mientras que a tiempos cortos el efecto de la interacción es aditivo. La forskolina reproduce el efecto de la TSH indicando que esta actúa por la vía de la proteína kinasa A (PKA). El IGF-1 tiene un efecto similar a la insulina, aunque no tan potente. El forbol miristato acetato (PMA) estimula el transporte de 2-DOG, indicando que este transporte es también regulado por la vía de la PKC. Se encontró que el efecto de la insulina es revertido parcialmente por un inhibidor de PKC, la staurosporina. Además se verifica aditividad entre la vía de la PKA y la vía de la PKC. Los yodoaraquidonatos IL-δ e ILω, que son hipotéticos intermediarios del fenómeno autorregulatorio, inhiben el transporte estimulado por TSH, insulina o ambas hormonas.Since the thyroid has very low glycogen stores it depends on the input of glucose in order to maintain its cellular function. The present Thesis work had as its main aim the study of the regulation of glucose transport in thyroid cells. An non-metabolizable analogue of glucose, 2-deoxyglucose (2-DOG), was utilized to measure glucose transport in the thyroid cell line FRTL-5. Both TSH and insulin stimulate glucose transport, and after 72 h of simultaneousincubation they have a synergic effect, while at shorter periods they have an additive action. Forskolin reproduces the effect of TSH, suggesting that this hormone acts via protein kinase A (PKA). IGF-1 had an effect similar to that of insulin, although not as potent. Phorbol myristate acetate (PMA) stimulates 2-DOG indicating that the PKC pathway also participates in the regulation of glucose transport. The effect of insulin was partially reversed by a PKC inhibitor, staurosporine. An additive effect was observed between the PKA and PKC pathways. Iodoarachidonates IL-δ and IL-ω, the hypothetical intermediates of the autoregulatory mechanism, inhibit 2-DOG transport stimulated by TSH, insulin or both togetherFil: Silberschmidt, Daniel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil: Pisarev, Mario A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Studies on the regulation of glucose transport in thyroid cells

El presente trabajo de tesis tuvo por objetivo principal estudiar la regulación del transporte de glucosa en células tiroideas. Se utilizó un análogo no metabolizable de la glucosa, la 2-deoxiglucosa, a fin de determinar la actividad de transporte de glucosa en la línea celular FRTL-5. Se encontró que tanto la insulina como la TSH estimulan el transporte, y que juntas a 72 horas tienen un efecto sinérgico, mientras que a tiempos cortos el efecto de la interacción es aditivo. La forskolina reproduce el efecto de la TSH indicando que esta actúa por la vía de la proteína kinasa A (PKA). El IGF-1 tiene un efecto similar a la insulina, aunque no tan potente. El forbol miristato acetato (PMA) estimula el transporte de 2-DOG, indicando que este transporte es también regulado por la vía de la PKC. Se encontró que el efecto de la insulina es revertido parcialmente por un inhibidor de PKC, la staurosporina. Además se verifica aditividad entre la vía de la PKA y la vía de la PKC. Los yodoaraquidonatos IL-δ e ILω, que son hipotéticos intermediarios del fenómeno autorregulatorio, inhiben el transporte estimulado por TSH, insulina o ambas hormonas.Since the thyroid has very low glycogen stores it depends on the input of glucose in order to maintain its cellular function. The present Thesis work had as its main aim the study of the regulation of glucose transport in thyroid cells. An non-metabolizable analogue of glucose, 2-deoxyglucose (2-DOG), was utilized to measure glucose transport in the thyroid cell line FRTL-5. Both TSH and insulin stimulate glucose transport, and after 72 h of simultaneousincubation they have a synergic effect, while at shorter periods they have an additive action. Forskolin reproduces the effect of TSH, suggesting that this hormone acts via protein kinase A (PKA). IGF-1 had an effect similar to that of insulin, although not as potent. Phorbol myristate acetate (PMA) stimulates 2-DOG indicating that the PKC pathway also participates in the regulation of glucose transport. The effect of insulin was partially reversed by a PKC inhibitor, staurosporine. An additive effect was observed between the PKA and PKC pathways. Iodoarachidonates IL-δ and IL-ω, the hypothetical intermediates of the autoregulatory mechanism, inhibit 2-DOG transport stimulated by TSH, insulin or both togetherFil: Silberschmidt, Daniel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

6 Iodo-δ-lactone reproduces many but not all the effects of iodide

Background: Iodide has direct effects on thyroid function. Several iodinated lipids are biosynthesized by the thyroid and they were postulated as intermediaries in the action of iodide. Among them 6 iodo-δ-lactone (IL-δ) has been identified and proposed to play a role in thyroid autoregulation. The aim of this study was to compare the effect of iodide and IL-δ on several thyroid parameters. Methods: Thyroid bovine follicles were incubated with the different compounds during three days. Results: KI and IL-δ inhibited iodide uptake, total protein and Tg synthesis but only KI had an effect on NIS and Tg mRNAs levels. Both compounds inhibited Na+/K+ ATPase and deoxy-glucose uptake. As PAX 8, FOXE 1 and TITF1 are involved in the regulation of thyroid specific genes their mRNA levels were measured. While iodide inhibited the expression of the first two, the expression of TITF1 was stimulated by iodide and IL-δ had no effect on these parameters. Conclusion: These findings indicate that IL-δ reproduces some but not all the effects of excess iodide. These observations apply for higher micromolar concentrations of iodide while no such effects could be demonstrated at nanomolar iodide concentrations.Fil: Thomasz, Lisa. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Oglio, Romina. Comisión Nacional de Energía Atómica; ArgentinaFil: Dagrosa, María A.. Comisión Nacional de Energía Atómica; ArgentinaFil: Krawiec, León. Comisión Nacional de Energía Atómica; ArgentinaFil: Pisarev, Mario Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Juvenal, Guillermo Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica; Argentin

High-affinity binding of T3 to Epididymis Nuclei

Thyroid hormones play an important role in epididymal function. Hypothyroid animals experience a significant decrease in the number and forward motility of sperm and a remarkable impairment of epididymal morphology. However, it is yet unknown if such activity is due to direct actions of iodothyronines on the target epididymis. The eventual identification of T3 receptors in the nucleous of epididymal cells becomes relevant. For this reason, the authors searched for specific high-affinity binding of T3 to these nuclei. Twenty prepuberal male Wistar rats were used. The testes and epididymis were approached as one unit through a scrotal incision. The fat-free epididymides were subjected to standard techniques to prepare the nuclei for incubations with 125I-T3Fil: Del Rio, A. G.. Universidad de Buenos Aires; ArgentinaFil: Blanco, A. M.. Universidad de Buenos Aires; ArgentinaFil: Pignataro, Omar Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Niepomniszcze, H.. Universidad de Buenos Aires. Facultad de Medicina. Hospital de Clínicas General San Martín; ArgentinaFil: Juvenal, Guillermo Juan. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pisarev, Mario Alberto. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

A new plant protein interacts with eIF3 and 60S to enhance virus-activated translation re-initiation

The plant viral re-initiation factor transactivator viroplasmin (TAV) activates translation of polycistronic mRNA by a re-initiation mechanism involving translation initiation factor 3 (eIF3) and the 60S ribosomal subunit (60S). QJ; Here, we report a new plant factor-re-initiation supporting protein (RISP)-that enhances TAV function in re-initiation. RISP interacts physically with TAV in vitro and in vivo. Mutants defective in interaction are less active, or inactive, in transactivation and viral amplification. RISP alone can serve as a scaffold protein, which is able to interact with eIF3 subunits a/c and 60S, apparently through the C-terminus of ribosomal protein L24. RISP pre-bound to eIF3 binds 40S, suggesting that RISP enters the translational machinery at the 43S formation step. RISP, TAV and 60S co-localize in epidermal cells of infected plants, and eIF3-TAV-RISP-L24 complex formation can be shown in vitro. These results suggest that RISP and TAV bridge interactions between eIF3-bound 40S and L24 of 60S after translation termination to ensure 60S recruitment during repetitive initiation events on polycistronic mRNA; RISP can thus be considered as a new component of the cell translation machinery