Histology and histopathology Vol.19, nº 2 (2004)

Ir a Estadísticas

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    To NO or not to NO, where, is the question
    (Murcia : F. Hernández, 2004) Govers, R.; Oess, S.
    Nitric oxide (NO) is a gaseous radical with unique biological functions essential for the cardiovascular system, host defense and neurotransmission. For two decades it was thought that NO was able to diffuse freely across relatively long distances and to traverse major parts of the cell, if not multiple cell layers. However, NO has been proven to be extremely reactive: it reacts with other reactive oxygen species, heavy metals, as well as with cysteine and tyrosine residues in proteins. In accordance, it is now widely accepted that once NO is generated, it is very short-lived and diffuses only over a short distance. This urges for the local production of NO and the localization of NO synthases in the proximity of their downstream targets. This review discusses the highly organized localization of NO synthases, with the endothelial isoform (eNOS) as its main focus, since from this synthase most is known about its subcellular localization and regulation.
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    A truncated isoform of the PP2A B56g regulatory subunit reduces irradiation-induced Mdm2 phosphorylation and could contribute to metastatic melanoma cell radioresistance
    (Murcia : F. Hernández, 2004) Koma, Y.-i.; Ito, A.; Watabe, K.; Kimura, S. H.; Kitamura, Y.
    F10, a subline of the B16 mouse melanoma cell line, is itself the parent of the more metastatic BL6 line. BL6 cells differ from F10 cells by an alteration of the gene encoding the B56g regulatory subunit of protein phosphatase 2A (PP2A), which results in mRNA encoding a truncated variant of the subunit (Dg1). Expression of Dg1 protein is detectable only when BL6 cells are transplanted into mice and then g-irradiated. Recently, B56g subunit-containing PP2A holoenzymes have shown to dephosphorylate Mdm2, a negative regulator of p53. Thus, we assessed whether the expression of Dg1 affects irradiation-induced phosphorylation of Mdm2 and radioresistance of melanoma cells by perturbing the regulation of p53. Western blot analyses revealed that irradiated COS-7 and NIH3T3 cells stably expressing Dg1 showed significantly less irradiation-induced Mdm2 phosphorylation. Mdm2 phosphorylation reduces the ability of Mdm2 to target p53 for degradation, which probably explained why p53 protein levels in NIH3T3 cells expressing Dg1 were not significantly elevated by irradiation, unlike in wild-type cells. This was also true for F10 cells transfected with Dg1 (F10Dg1) when the cells expressed Dg1 after being irradiated in vivo. p53 mRNA levels in irradiated wild-type and Dg1-expressing cells were both only slightly elevated, suggesting that Mdm2 regulates p53 levels by a post-transcriptional mechanism. p53-mediated induction of the pro-apoptotic gene encoding Bax was also significantly lower in F10Dg1 cells irradiated in vivo. Moreover, F10Dg1 and BL6 cells were less apoptotic than F10 cells when the cells were irradiated in vivo. The p53 in F10 cells appears to be as functional as that in NIH3T3 cells because irradiation-induced expression of p53-target genes was comparable in both cells. Collectively, Dg1 appears to reduce irradiation-induced Mdm2 phosphorylation, which then blocks irradiation-stimulated p53 accumulation. Defects, such as Dg1, in PP2A may thus contribute to melanoma cell radioresistance.
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    Amplification of CDK4, MDM2, SAS and GLI genes in leiomyosarcoma, alveolar and embryonal rhabdomyosarcoma
    (Murcia : F. Hernández, 2004) Ragazzini, P.; Gamberi, G.; Pazzaglia, L.; Serra, M.; Magagnoli, Giovanna; Ponticelli, F.; Ferrari, C.; Ghinelli, C.; Alberghini, M.; Bertoni, F.; Picci, P.; Benassi, M.S.
    We evaluated amplification and overrepresentation of CDK4, MDM2, GLI and SAS genes of the 12q13-15 region, in a group of soft tissue sarcomas including leiomyosarcomas (LMS), alveolar rhabdomyosarcomas (ARMS) and embryonal (anaplastic and classic variants) rhabdomyosarcomas (ERMS), to ascertain genomic alterations and possible differences within histologic subtypes of rhabdomyosarcoma (RMS). Quantitative real-time PCR was performed on DNA samples from 29 LMS, 9 ARMS, 7 anaplastic ERMS and 6 classic ERMS. Alteration of one or more of the 12q13-15 genes was revealed in 13/29 LMS (45%) and 12/22 RMS (54%) including 5/9 ARMS (56%), 5/7 anaplastic ERMS (71%) and 2/6 classic ERMS (33%). The potential importance of overproduction of protein products in neoplastic development, led us also to study a possible high expression of cdk4, mdm2 and gli proteins in immunohistochemical staining experiments on paraffin-embedded tissue samples of the same cases. Among LMS and RMS most cases with CDK4, MDM2 and GLI gene alterations also showed a simultaneous high expression of the relative protein. In summary, these results indicate that amplification or overerepresentation of genes at 12q13-15 region involve both LMS and RMS. Moreover these genes alterations reveal predominantly in the alveolar and in the anaplastic variant of the embryonal subtype. These two seem to have a more similar behavior than anaplastic and classic embryonal that are classified in the same subtype.
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    Cholinergic, nitrergic and peptidergic (Substance P- and CGRP-utilizing) innervation of the horse intestine. A histochemical and immunohistochemical study
    (Murcia : F. Hernández, 2004) Domeneghini, C.; Radaelli, G.; Arrighi, S.; Bosi, G.; Dolera, M.
    The small and large intestine of adult horses were histochemically and immunohistochemically investigated in order to evidence components of the intramural nervous system. The general structural organization of the intramural nervous system was examined by using Nissl-thionin staining as well as the anti-neurofilament 200 (NF200) immunoreaction, which demonstrated the presence of neurons in the submucous as well as myenteric plexuses. The additional presence of subserosal ganglia was shown in the large intestine. Acetylcholinesterase (AChEase) activity was observed in both the submucous and myenteric plexuses. Localization of acetylcholine-utilizing neurons was also evidenced by immunohistochemical reactions for choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT). With both histochemistry and immunohistochemistry possible cholinergic nerve fibres were detected in the inner musculature. The two possible cholinergic co-mediators Calcitonin Gene-Related Peptide (CGRP) and Substance P (SP) have been investigated by an immunohistochemical approach. CGRP immunoreactivity was detected in roundish nerve cell bodies as well as in nerve fibres of the submucous plexus, whereas SP immunoreactivity was evidenced in nerve fibres of the tunica mucosa, in nerve cell bodies and fibres of the submucous plexus and in nerve fibres of the myenteric plexus. NADPH-diaphorase reactivity, which is linked to the synthesis and release of nitric oxide, was detected in nerve cell bodies and nerve fibres of both the submucous and myenteric plexuses as well as in a subserosal localization of the large intestine. The nitrergic components were confirmed by the anti-NOS (nitric oxide synthase) immunoreaction. Results are compared with those of other mammals and related to the complex intestinal horse physiology and pathophysiology.