Mechano-regulated tenascin-C orchestrates muscle repair

Tenascin-C (TNC) is a mechano-regulated, morphogenic, extracellular matrix protein that is associated with tissue remodeling. The physiological role of TNC remains unclear because transgenic mice engineered for a TNC deficiency, via a defect in TNC secretion, show no major pathologies. We hypothesized that TNC-deficient mice would demonstrate defects in the repair of damaged leg muscles, which would be of functional significance because this tissue is subjected to frequent cycles of mechanical damage and regeneration. TNC-deficient mice demonstrated a blunted expression of the large TNC isoform and a selective atrophy of fast-muscle fibers associated with a defective, fast myogenic expression response to a damaging mechanical challenge. Transcript profiling mapped a set of de-adhesion, angiogenesis, and wound healing regulators as TNC expression targets in striated muscle. Expression of these regulators correlated with the residual expression of a damage-related 200-kDa protein, which resembled the small TNC isoform. Somatic knockin of TNC in fast-muscle fibers confirmed the activation of a complex expression program of interstitial and slow myofiber repair by myofiber-derived TNC. The results presented here show that a TNC-orchestrated molecular pathway integrates muscle repair into the load-dependent control of the striated muscle phenotype.

The Protein-tyrosine-phosphatase SHP2 is phosphorylated on serine residues 576 and 591 by protein kinase C isoforms alpha, beta 1, beta 2, and eta

To study whether protein kinase C (PKC) isoforms can interact with protein-tyrosine-phosphatases (PTPs) which are connected to the insulin signaling pathway, we co-overexpressed PKC isoforms together with insulin receptor, docking proteins, and the PTPs SHP1 and SHP2 in human embryonic kidney (HEK) 293 cells. After phorbol ester induced activation of PKC isoforms alpha, beta 1, beta 2, and eta, we could show a defined gel mobility shift of SHP2, indicating phosphorylation on serine/threonine residues. This phosphorylation was not dependent on insulin receptor or insulin receptor substrate-1 (IRS-1) overexpression and did not occur for the closely related phosphatase SHP1. Furthermore, PKC phosphorylation of SHP2 was completely blocked by the PKC inhibitor bisindolylmaleimide and was not detectable when SHP2 was co-overexpressed with kinase negative mutants of PKC beta 1 and -beta 2. The phosphorylation also occurred on endogenous SHP2 in Chinese hamster ovary (CHO) cells stably overexpressing PKC beta 2. Using point mutants of SHP2, we identified serine residues 576 and 591 as phosphorylation sites for PKC. However, no change of phosphatase activity by TPA treatment was detected in an in vitro assay. In summary, SHP2 is phosphorylated on serine residues 576 and 591 by PKC isoforms alpha, beta 1, beta 2, and eta.

Ueber Wistaria chinensis D. C. (Glycine sinensis Bol. May)

Von Juwelier M. Hermann

Immago Spectaculi quod, in Nobiliore Theatro de vico S Benedicti, Magnis Russiæ Ducibus Nicolaus Michaelius, et Philippus Calbo, Sapienties Ærario Præfecti, ex D. C. exhibuerunt XI. Kal. Feb. MDCCLXXXII.

Signatur des Originals: S 36/G04596

Astronomía, astrología y política en Marco Tulio Cicerón S.I A.C y en Marco Manilio S.I D.C.

Realizamos un estudio de la "simpatía cósmica": la visión filosófica unificada y armónica del universo propia del Estoicismo Medio de Panecio y Posidonio y su influencia en estos dos autores. Analizamos la relación de la astronomía y de la astrología vinculada al aspecto político-filosófico en De Republica de Cicerón, y en las Astronomica de Manilio: planteamos interrogantes acerca de la causa de esta vinculación, e indagamos en la posible necesidad, en el caso de Manilio, de enmascarar políticamente una posición filosófica. Las referencias a Augusto en la obra de Manilio, a los grandes héroes de Roma en la de Cicerón, o el hecho de "mostrar" la grandeza de Roma, o la buena estrella de sus gobernantes son algunas de las estrategias argumentativas utilizadas: el empleo de recursos retóricos como la "escenificación" y la "analogía", entre otros, "ayudarían" a sostener una determinada postura ideológica política y filosófica en los mencionados autores

Representaciones de la vejez y formas del discurso ejemplar romano durante el S. I d.C.

Examinaremos cómo la vejez en el corpus fedriano se configura a partir de los diálogos que este establece con sus contextos literarios y culturales. Así, la construcción de la ancianidad femenina incorpora estereotipos cómicosatíricos que evidencian la perspectiva romanocéntrica desde la que el género se reformula (Phaed.2.2 y 3.1). Por su parte, la debilidad atribuida a los ancianos (Phaed.1.15 y 1.21) -leída en contraposición con la fortaleza que su contemporáneo, Valerio Máximo, adjudica a la ancianidad modélica en sus exempla (V. Max. 8.13)- contribuye a la construcción de la máscara del fabulista como sujeto marginal (3. 9 y 3. epil.).

Juan Antonio López Férez (Ed.) Desde los poemas homéricos hasta la prosa griega del siglo IV d. C., Madrid, Ediciones Clásicas, 1999, VIII + 523 pp.

Fil: Chazarreta, Daniela Evangelina. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.