p53: 25 years of research and more questions to answer.
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Animals↗
Biomedical subjects
G Melino
Publications and source records attributed to G Melino.
Type I lamellar ichthyosis improved by tazarotene 0.1% gel.
The efficacy of tazarotene 0.1% gel in a 30-year-old woman with type I lamellar ichthyosis is reported. The drug was applied to 15% of the total body surface area as follows: once daily for 2 weeks, three times a week for further 2 weeks, followed by a once weekly maintenance application. During the first week of treatment there was partial improvement obtained and in the next 14 days further reduction of scaling within the tazarotene-treated areas was observed. After 4 months of maintenance application, there was a marked overall improvement in the treated areas. Side-effects consisted only of mild pruritus, slight burning and irritation. In essence, the therapeutic benefit obtained was comparable with that of systemic retinoids but without the adverse systemic side-effects. As noted in other reports, tazarotene 0.1% gel seems to be a valuable and safe therapeutic option for this severe genodermatosis.
Administration, Topical↗
The European death flying circus.
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Animals↗
'Tissue' transglutaminase ablation reduces neuronal death and prolongs survival in a mouse model of Huntington's disease.
By crossing Huntington's disease (HD) R6/1 transgenic mice with 'tissue' transglutaminase (TG2) knock-out mice, we have demonstrated that this multifunctional enzyme plays an important role in the neuronal death characterising this disorder in vivo. In fact, a large reduction in cell death is observed in R6/1, TG2(-/-) compared with R6/1 transgenic mice. In addition, we have shown that the formation of neuronal intranuclear inclusions (NII) is potentiated in absence of the 'tissue' transglutaminase. These phenomena are paralleled by a significant improvement both in motor performances and survival of R6/1, TG2(-/-) versus R6/1 mice. Taken together these findings suggest an important role for tissue transglutaminase in the regulation of neuronal cell death occurring in Huntington's disease.
Animals↗
The adenine nucleotide translocator: a target of nitric oxide, peroxynitrite, and 4-hydroxynonenal.
Nitric oxide (NO), peroxynitrite, and 4-hydroxynonenal (HNE) may be involved in the pathological demise of cells via apoptosis. Apoptosis induced by these agents is inhibited by Bcl-2, suggesting the involvement of mitochondria in the death pathway. In vitro, NO, peroxynitrite and HNE can cause direct permeabilization of mitochondrial membranes, and this effect is inhibited by cyclosporin A, indicating involvement of the permeability transition pore complex (PTPC) in the permeabilization event. NO, peroxynitrite and HNE also permeabilize proteoliposomes containing the adenine nucleotide translocator (ANT), one of the key components of the PTPC, yet have no or little effects on protein-free control liposomes. ANT-dependent, NO-, peroxynitrite- or HNE-induced permeabilization is at least partially inhibited by recombinant Bcl-2 protein, as well as the antioxidants trolox and butylated hydroxytoluene. In vitro, none of the tested agents (NO, peroxynitrite, HNE, and tert-butylhydroperoxide) causes preferential carbonylation HNE adduction, or nitrotyrosylation of ANT. However, all these agents induced ANT to undergo thiol oxidation/derivatization. Peroxynitrite and HNE also caused significant lipid peroxidation, which was antagonized by butylated hydroxytoluene but not by recombinant Bcl-2. Transfection-enforced expression of vMIA, a viral apoptosis inhibitor specifically targeted to ANT, largely reduces the mitochondrial and nuclear signs of apoptosis induced by NO, peroxynitrite and HNE in intact cells. Taken together these data suggest that NO, peroxynitrite, and HNE may directly act on ANT to induce mitochondrial membrane permeabilization and apoptosis.
Aldehydes↗
Transglutaminase 5 cross-links loricrin, involucrin, and small proline-rich proteins in vitro.
Transglutaminases (TGases) are seven enzymes, cross-linking proteins by gamma-glutamil-epsilon-lysine bonds, four of which are expressed in the skin. A new member of the TGase family, TGase 5, has been identified recently, and in the present study we evaluated its role in keratinocyte differentiation in vitro. In addition to the previously described isoforms, full-length TGase 5 and Delta3 (deletion of exon 3), we identified two new splicing variants, Delta11 and Delta3Delta11 (deletion of exons 11 or 3, 11). We expressed full-length TGase 5, Delta3, Delta11, and Delta3Delta11 isoforms in the keratinocyte and baculovirus systems. The results indicate that both full-length TGase 5 and Delta11 are active, whereas Delta3 and Delta3Delta11 have very low activity. Expression studies show that full-length TGase 5 is induced during the early stages of keratinocyte differentiation and is differently regulated in comparison with the other epidermal TGases. Kinetic and in vitro cross-linking experiments indicate that full-length TGase 5 is very efficient in using specific epidermal substrates (loricrin, involucrin, and SPR3). In keratinocyte expression system, TGase 5 isoforms are retained in an intermediate filament-enriched fraction, suggesting its association with insoluble proteins. Indeed, TGase 5 co-localize with vimentin and it is able to cross-link vimentin in vitro.
Baculoviridae↗
Induction of gene expression via activator protein-1 in the ascorbate protection against UV-induced damage.
UV irradiation is a major insult to the skin. We have shown previously that exogenous vitamin C (ascorbate) accumulates in HaCaT keratinocytes, thus conferring the ability to prevent radical formation and cell death elicited by UV-B. Here, we have investigated the potential mechanisms accounting for the cytoprotective effects exerted by this antioxidant. Using a cDNA microarray hybridization, we identified several genes whose expression was up-regulated by ascorbate. We focused on the fra-1 gene, a member of the Fos family of transcription factors that down-regulates activator protein-1 (AP-1) target genes. Both in HaCaT and in normal human epidermal keratinocytes, we found Fra-1 mRNA induction as early as 2 h after ascorbate loading. Electrophoretic mobility-shift assay and antibody supershift analysis revealed that ascorbate modulates AP-1 DNA-binding activity and that Fra-1 is in AP-1 complexes in treated cells. Furthermore, transient-transfection studies, using an AP-1 reporter construct, showed that ascorbate was able to inhibit both basal and UV-B-induced AP-1-dependent transcription. Ascorbate also modulates UV-B-induced AP-1 activity by preventing the phosphorylation and activation of the upstream c-Jun N-terminal kinase (JNK), thus inhibiting phosphorylation of the endogenous c-Jun protein. These data suggest that ascorbate mediates cellular responses aimed at counteracting UV-mediated cell damage and cell death by interfering at multiple levels with the activity of the JNK/AP-1 pathway and modulating the expression of AP-1-regulated genes.
Ascorbic Acid↗
Apoptosis in neuroblastomas induced by interferon-gamma involves the CD95/CD95L pathway.
BACKGROUND AND PROCEDURE: The CD95/CD95 ligand (CD95L) system is a key regulator of apoptosis. To evaluate a possible role of the CD95/CD95L system in human neuroblastoma (NB) cells, we investigated the constitutive and interferongamma (INFgamma)-induced expression of CD95 and CD95L, and CD95-mediated cell death in the SK-N-BE(2) cell line. RESULTS: Modulation of CD95/CD95L expression and triggering of an autocrine apoptotic mechanism by IFNgamma suggest a potential role for INFgamma as a therapeutic agent for NB. CONCLUSIONS: The evidence that retinoids induce apoptosis via tissue transglutaminase (tTG) and that N-methyl-D-aspartate (NMDA) and gp120 act through the nitric oxide synthase (NOS) activation pathway, indicates the existence of different molecular mechanisms of action, whose pharmacological exploitation might be used in an additive fashion.
Apoptosis↗
Publications in cell death: the golden age.
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Animals↗
The European Cell Death Group.
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Apoptosis↗
Lipoxygenases and their involvement in programmed cell death.
Lipoxygenases are a family of enzymes which dioxygenate unsaturated fatty acids, thus initiating lipoperoxidation of membranes and the synthesis of signaling molecules. Consequently, they induce structural and metabolic changes in the cell in a number of pathophysiological conditions. Recently, a pro-apoptotic effect of lipoxygenase, and of the hydroperoxides produced thereof, has been reported in different cells and tissues, leading to cell death. Anti-apoptotic effects of lipoxygenases have also been reported; however, this has often been based on the use of enzyme inhibitors. Here we review the characteristics of the lipoxygenase family and its involvement in the initiation of oxidative stress-induced apoptosis. Finally, we discuss the role of lipoxygenase activation in apoptosis of animal and plant cells, suggesting a common signal transduction pathway in cell death conserved through evolution of both kingdoms.
Animals↗
Human delta Np73 regulates a dominant negative feedback loop for TAp73 and p53.
Inactivation of the tumour suppressor p53 is the most common defect in cancer cells. p53 is a sequence specific transcription factor that is activated in response to various forms of genotoxic stress to induce cell cycle arrest and apoptosis. Induction of p53 is subjected to complex and strict control through several pathways, as it will often determine cellular fate. The p73 protein shares strong structural and functional similarities with p53 such as the potential to activate p53 responsive genes and the ability to induce apoptosis. In addition to alternative splicing at the carboxyl terminus which yields several p73 isoforms, a p73 variant lacking the N-terminal transactivation domain (Delta Np73) was described in mice. In this study, we report the cloning and characterisation of the human Delta Np73 isoforms, their regulation by p53 and their possible role in carcinogenesis. As in mice, human Delta Np73 lacks the transactivation domain and starts with an alternative exon (exon 3'). Its expression is driven by a second promoter located in a genomic region upstream of this exon, supporting the idea of two independently regulated proteins, derived from the same gene. As anticipated, Delta Np73 is capable of regulating TAp73 and p53 function since it is able to block their transactivation activity and their ability to induce apoptosis. Interestingly, expression of the Delta Np73 is strongly up-regulated by the TA isoforms and by p53, thus creating a feedback loop that tightly regulates the function of TAp73 and more importantly of p53. The regulation of Delta Np73 is exerted through a p53 responsive element located on the Delta N promoter. Expression of Delta Np73 not only regulates the function of p53 and TAp73 but also shuts off its own expression, once again finely regulating the whole system. Our data also suggest that increased expression of Delta Np73, functionally inactivating p53, could be involved in tumorogenesis. An extensive analysis of the expression pattern of Delta Np73 in primary tumours would clarify this issue.
Amino Acid Sequence↗
Novel mutations of the transglutaminase 1 gene in lamellar ichthyosis.
Lamellar ichthyosis, one form of congenital autosomal recessive ichthyosis, is caused by mutations in the gene (TGM1) encoding the transglutaminase 1 enzyme. Mutations, deletions, or insertion of TGM1 have been reported so far. Here we report that three novel mutations of TGM1, D101V, N288T, and R306W, cause lamellar ichthyosis in two different families. The patient in family LI-KD has N288T and R306W mutations, and the patient in family LI-LK has D101V and R306W mutations. The activity of the transglutaminase 1 enzyme of the patient in family LI-LK was only about 15% of normal. Also, three-dimensional structural prediction analyses revealed that the N288T and R306W mutations, and possibly the D101V mutation, cause misfolding in the central catalytic core domain of the transglutaminase 1 enzyme that would probably result in reduced enzyme activity. Our data suggest that the greatly reduced transglutaminase 1 activities are due to disruptions of the native folding of transglutaminase 1, and that these mutations may play a critical role in the pathology of lamellar ichthyosis.
Amino Acid Substitution↗
Novel and recurrent mutations in the genes encoding keratins K6a, K16 and K17 in 13 cases of pachyonychia congenita.
Thirteen patients with pachyonychia congenita types 1 and 2 were studied, two of which had a family history of pachyonychia and 11 of which were sporadic cases. Heterozygous mis-sense or small in-frame insertion/deletion mutations were detected in the genes encoding keratins K6a, K16, and K17 in all cases. Three novel mutations, F174V, E472K, and L469R were found in the K6a gene. Two novel mutations, M121T and L128Q were detected in K16. Similarly, three novel mutations, L95P, S97del, and L99P were found in K17. In addition, we identified recurrent mutations N171del (three instances) and F174S in K6a and R94H in K17. Analysis of both phenotype and genotype data led to the following conclusions: (i) K6a or K16 mutations produce the pachyonychia congenita type 1 phenotype, whereas K17 (or K6b) mutations cause pachyonychia congenita type 2; (ii) the presence of pilosebaceous cysts following puberty is the best indicator of pachyonychia congenita type 2; (iii) prepubescent patients are more difficult to classify due to the lack of cysts; and (iv) natal teeth are indicative of pachyonychia congenita type 2, although their absence does not preclude the pachyonychia congenita type 2 phenotype. This study establishes useful diagnostic criteria for pachyonychia congenita types 1 and 2, which will help limit unnecessary DNA analysis in the diagnosis and management of this genetically heterogeneous group of genodermatoses.
DNA Mutational Analysis↗
Gene disruption of tissue transglutaminase.
Transglutaminase 2 (TGase 2), or tissue transglutaminase, catalyzes either epsilon-(gamma-glutamyl)lysine or N(1), N(8)-(gamma-glutamyl)spermidine isopeptide bonds. TGase 2 expression has been associated with apoptosis, and it has been proposed that its activation should lead to the irreversible assembly of a cross-linked protein scaffold in dead cells. Thus, TGase 2-catalyzed protein polymerization contributes to the ultrastructural changes typical of dying apoptotic cells; it stabilizes the integrity of the apoptotic cells, preventing the release of harmful intracellular components into the extracellular space and, consequently, inflammation and scar formation. In order to perform a targeted disruption of the enzyme, we prepared a construct deleting part of exons 5 and 6, containing the active site, and intron 5. Complete absence of TGase 2 was demonstrated by reverse transcription-PCR and Western blot analysis. TGase activity measured on liver and thymus extracts showed, however, a minimal residual activity in TGase 2(-/-) mice. PCR analysis of mRNA extracted from the same tissues demonstrated that at least TGase 1 (normally present in the skin) is also expressed in these tissues and contributes to this residual activity. TGase 2(-/-) mice showed no major developmental abnormalities, and histological examination of the major organs appeared normal. Induction of apoptosis ex vivo in TGase 2(-/-) thymocytes (by CD95, dexamethasone, etoposide, and H(2)O(2)) and in vitro on TGase 2(-/-) mouse embryonal fibroblasts (by retinoids, UV, and H(2)O(2)) showed no significant differences. A reduction in cross-linked apoptotic bodies with a modestly increased release of lactate dehydrogenase has been detected in some cases. Together our results show that TGase 2 is not a crucial component of the main pathway of the apoptotic program. It is possible that the residual enzymatic activity, due to TGase 1 or redundancy of other still-unidentified TGases, can compensate for the lack of TGase 2.
Animals↗
A novel mutation in the keratin 13 gene causing oral white sponge nevus.
White sponge nevus (WSN) is an autosomal-dominantly inherited form of mucosal leukokeratosis. Defects in keratins, proteins that form the stress-bearing cytoskeleton in epithelia, have been shown to cause several epithelial fragility disorders. Recently, mutations in the genes encoding mucosal-specific keratins K4 and K13 were shown to be the underlying cause of WSN. We have studied a large Scottish family with 19 persons affected by WSN in four generations. The K4 locus was excluded by genetic linkage analysis; however, genetic linkage consistent with a K13 defect was obtained. Subsequently, a heterozygous missense mutation 335A>G was detected in exon 1 of the KRT13 gene, predicting the amino acid change N112S in the 1A domain of the K13 polypeptide. The mutation was confirmed in affected family members and was excluded from 50 unaffected people by restriction enzyme analysis. These results confirm that mucosal keratin defects are the cause of WSN.
Adenine↗