Publications by authors named "Ana Fontalba"

21 Publications

  • Page 1 of 1

Radixin modulates the function of outer hair cell stereocilia.

Commun Biol 2020 Dec 23;3(1):792. Epub 2020 Dec 23.

Department of Biomedical and Clinical Sciences, Linköping University, SE-581 83, Linköping, Sweden.

The stereocilia of the inner ear sensory cells contain the actin-binding protein radixin, encoded by RDX. Radixin is important for hearing but remains functionally obscure. To determine how radixin influences hearing sensitivity, we used a custom rapid imaging technique to visualize stereocilia motion while measuring electrical potential amplitudes during acoustic stimulation. Radixin inhibition decreased sound-evoked electrical potentials. Other functional measures, including electrically induced sensory cell motility and sound-evoked stereocilia deflections, showed a minor amplitude increase. These unique functional alterations demonstrate radixin as necessary for conversion of sound into electrical signals at acoustic rates. We identified patients with RDX variants with normal hearing at birth who showed rapidly deteriorating hearing during the first months of life. This may be overlooked by newborn hearing screening and explained by multiple disturbances in postnatal sensory cells. We conclude radixin is necessary for ensuring normal conversion of sound to electrical signals in the inner ear.
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http://dx.doi.org/10.1038/s42003-020-01506-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7758333PMC
December 2020

Rare Variants in 48 Genes Account for 42% of Cases of Epilepsy With or Without Neurodevelopmental Delay in 246 Pediatric Patients.

Front Neurosci 2019 8;13:1135. Epub 2019 Nov 8.

Genomes & Disease Group, Molecular Medicine and Chronic Diseases Research Centre (CiMUS), Santiago de Compostela University-IDIS, Santiago de Compostela, Spain.

In order to characterize the genetic architecture of epilepsy in a pediatric population from the Iberian Peninsula (including the Canary Islands), we conducted targeted exome sequencing of 246 patients with infantile-onset seizures with or without neurodevelopmental delay. We detected 107 variants in 48 different genes, which were implicated in neuronal excitability, neurodevelopment, synaptic transmission, and metabolic pathways. In 104 cases (42%) we detected variant(s) that we classified as pathogenic or likely pathogenic. Of the 48 mutated genes, 32 were dominant, 8 recessive and 8 X-linked. Of the patients for whom family studies could be performed and in whom pathogenic variants were identified in dominant or X-linked genes, 82% carried mutations. The involvement of small copy number variations (CNVs) is 9%. The use of progressively updated custom panels with high mean vertical coverage enabled establishment of a definitive diagnosis in a large proportion of cases (42%) and detection of CNVs (even duplications) with high fidelity. In 10.5% of patients we detected associations that are pending confirmation via functional and/or familial studies. Our findings had important consequences for the clinical management of the probands, since a large proportion of the cohort had been clinically misdiagnosed, and their families were subsequently able to avail of genetic counseling. In some cases, a more appropriate treatment was selected for the patient in question, or an inappropriate treatment discontinued. Our findings suggest the existence of modifier genes that may explain the incomplete penetrance of some epilepsy-related genes. We discuss possible reasons for non-diagnosis and future research directions. Further studies will be required to uncover the roles of structural variants, epimutations, and oligogenic inheritance in epilepsy, thereby providing a more complete molecular picture of this disease. In summary, given the broad phenotypic spectrum of most epilepsy-related genes, efficient genomic tools like the targeted exome sequencing panel described here are essential for early diagnosis and treatment, and should be implemented as first-tier diagnostic tools for children with epilepsy without a clear etiologic basis.
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http://dx.doi.org/10.3389/fnins.2019.01135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6856296PMC
November 2019

Quality of life in patients with hereditary haemorrhagic telangiectasia (HHT).

Health Qual Life Outcomes 2017 Jan 23;15(1):19. Epub 2017 Jan 23.

Department of Radiology, Hospital Universitario Marqués de Valdecilla and Instituto de Investigación Valdecilla (IDIVAL), Santander, Spain.

Background: There are very few studies about general quality of life parameters, standards for the description of health status and comparison with general population data on patients with Hereditary hemorrhagic telangiectasia (HHT), a rare disease in which epistaxis is a cardinal symptom.

Purpose: To assess the quality of life in a population of Spanish patients with HHT and compare it with the general population.

Design And Methods: Between January 1 2005 and December 31 2013, 187 adult patients diagnosed with HHT who were admitted to the HHT Unit of the Hospital Sierrallana, completed on their first visit, the EuroQol 5D-3L (five dimensions and three levels) quality of life descriptive test and the visual analog scale (VAS). The numerical social index value was also determined and the subjective effect of the nasal epistaxis on their quality of life was estimated classified as mild, moderate or severe.

Results: Patients with HHT had greater problems than the general population in the five dimensions of the EuroQol 5D-3L, particularly considering pain/discomfort and anxiety/depression. In the VAS and the social index value, patients with HHT also scored lower than the general population, particularly older patients, males, and patients with HHT2. They also had values similar to those of populations with chronic illnesses. The subjective perception of the severity of epistaxis correlated strongly with the VAS and social index values.

Conclusions: The quality of life of patients with HHT, estimated using the EuroQol 5D-3L scale, is affected across all dimensions. The scores are similar to those seen in cases of other chronic diseases. Older patients, males and the carriers of the ACVRL1 mutation generally have worse scores on these scales. The VAS and the social index value are index that correlate well with the severity of the clinical symptoms associated mainly with epistaxis.
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http://dx.doi.org/10.1186/s12955-017-0586-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5259834PMC
January 2017

Copy number variations in endoglin locus: mapping of large deletions in Spanish families with hereditary hemorrhagic telangiectasia type 1.

BMC Med Genet 2013 Nov 25;14:121. Epub 2013 Nov 25.

Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain.

Background: The hereditary hemorrhagic telangiectasia syndrome (HHT), also known as the Rendu-Osler-Weber syndrome is a multiorganic vascular disorder inherited as an autosomal dominant trait. Diagnostic clinical criteria include: epistaxis, telangiectases in mucocutaneous and gastrointestinal sites, arteriovenous malformations (AVMs) most commonly found in pulmonary, hepatic and cerebral circulations, and familial inheritance. HHT is transmitted in 90% of the cases as an autosomal dominant condition due to mutations in either endoglin (ENG), or activin receptor-like kinase 1 (ACVRL1/ALK1) genes (HHT type 1 and 2, respectively).

Methods: We have carried out a genetic analysis of four independent Spanish families with HHT clinical criteria, which has permitted the identification of new large deletions in ENG. These mutations were first detected using the MLPA technique and subsequently, the deletion breakpoints were mapped using a customized copy number variation (CNV) microarray. The array was designed to cover the ENG gene and surrounding areas.

Results: All tested families carried large deletions ranging from 3-kb to 100-kb, involving the ENG gene promoter, several ENG exons, and the two downstream genes FGSH and CDK9. Interestingly, common breakpoints coincident with Alu repetitive sequences were found among these families.

Conclusions: The systematic hybridization of DNA from HHT families, with deletions or duplications, to custom designed microarrays, could allow the mapping of breakpoints, coincident with repetitive Alu sequences that might act as "hot spots" in the development of chromosomal anomalies.
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http://dx.doi.org/10.1186/1471-2350-14-121DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4222255PMC
November 2013

Genetic diagnosis of X-linked dominant Hypophosphatemic Rickets in a cohort study: tubular reabsorption of phosphate and 1,25(OH)2D serum levels are associated with PHEX mutation type.

BMC Med Genet 2011 Sep 8;12:116. Epub 2011 Sep 8.

Fundación Pública Galega de Medicina Xenómica, Santiago de Compostela, Spain.

Background: Genetic Hypophosphatemic Rickets (HR) is a group of diseases characterized by renal phosphate wasting with inappropriately low or normal 1,25-dihydroxyvitamin D3 (1,25(OH)2D) serum levels. The most common form of HR is X-linked dominant HR (XLHR) which is caused by inactivating mutations in the PHEX gene. The purpose of this study was to perform genetic diagnosis in a cohort of patients with clinical diagnosis of HR, to perform genotype-phenotype correlations of those patients and to compare our data with other HR cohort studies.

Methods: Forty three affected individuals from 36 non related families were analyzed. For the genetic analysis, the PHEX gene was sequenced in all of the patients and in 13 cases the study was complemented by mRNA sequencing and Multiple Ligation Probe Assay. For the genotype-phenotype correlation study, the clinical and biochemical phenotype of the patients was compared with the type of mutation, which was grouped into clearly deleterious or likely causative, using the Mann-Whitney and Fisher's exact test.

Results: Mutations in the PHEX gene were identified in all the patients thus confirming an XLHR. Thirty four different mutations were found distributed throughout the gene with higher density at the 3' end. The majority of the mutations were novel (69.4%), most of them resulted in a truncated PHEX protein (83.3%) and were family specific (88.9%). Tubular reabsorption of phosphate (TRP) and 1,25(OH)2D serum levels were significantly lower in patients carrying clearly deleterious mutations than in patients carrying likely causative ones (61.39 ± 19.76 vs. 80.14 ± 8.80%, p = 0.028 and 40.93 ± 30.73 vs. 78.46 ± 36.27 pg/ml, p = 0.013).

Conclusions: PHEX gene mutations were found in all the HR cases analyzed, which was in contrast with other cohort studies. Patients with clearly deleterious PHEX mutations had lower TRP and 1,25(OH)2D levels suggesting that the PHEX type of mutation might predict the XLHR phenotype severity.
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http://dx.doi.org/10.1186/1471-2350-12-116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3189111PMC
September 2011

Expression and function of toll-like receptors in peripheral blood mononuclear cells of patients with polymyalgia rheumatica and giant cell arteritis.

Ann Rheum Dis 2011 Sep 13;70(9):1677-83. Epub 2011 Jun 13.

Servicio de Reumatología, Universidad de Cantabria, Hospital Universitario Marqués de Valdecilla-IFIMAV, Santander, Spain.

Objective: To investigate the expression and function of the Toll-like receptor (TLR) family in peripheral blood mononuclear cells (PBMCs) of patients with polymyalgia rheumatica (PMR) and giant cell arteritis (GCA).

Methods: The authors analysed 70 patients with PMR, 20 with GCA, and 24 healthy controls (HC). TLR expression was assessed by flow cytometry. TLR function was assessed by stimulating PBMCs with specific ligands.

Results: A significantly increased expression of TLR7 in PBMCs of patients with active disease compared with HC was found. Despite increased expression of TLR7, circulating monocytes from patients showed a significantly lower in vitro response to TLR7 agonists. No amino acid substitutions predicted to be functionally damaging were found in TLR7. A normal response to specific TLR7 agonists in patients in complete remission eliminated a genetic defect. TLR expression and function were also affected to some degree in other diseases characterised by a strong acute phase response.

Conclusion: These data suggest activation of TLR7 during the active phase of PMR and GCA which resolves with complete disease remission. Whether this finding is the consequence of the marked inflammatory process in these disorders or activation by natural ligands remains to be explored.
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http://dx.doi.org/10.1136/ard.2010.140194DOI Listing
September 2011

Hereditary pancreatitis: clinical features and inheritance characteristics of the R122C mutation in the cationic trypsinogen gene (PRSS1) in six Spanish families.

JOP 2009 May 18;10(3):249-55. Epub 2009 May 18.

Hepato-Gastroenterology Unit, Marqués de Valdecilla Universitary Hospital, Santander, Spain.

Context: Hereditary pancreatitis is an autosomal dominant disease which is caused by mutations in the PRSS1 gene.

Objective: The aim of our study was to describe the penetrance and phenotype-genotype correlations of the c.346C>T (p.R122C) mutation.

Design: Case series descriptive study.

Patients: Forty-one members of six families from whom DNA samples were analyzed.

Main Outcome Measures: In subjects with R122C mutation symptoms, pancreatic calcifications, main pancreatic duct changes, diabetes, steatorrhea, pancreatic cancer and surgery were recorded.

Results: The R122C mutation was detected in 22 of the 41 family members studied, and 7 men and 2 women developed pancreatic disease, resulting in a penetrance of 40.9%. One out of the 9 patients was excluded because she died before the mutation was detected. The mean age at symptom onset was 23.5 years (range: 4-51 years). Abdominal pain was present in 6 (75.0%) of the 8 patients with the R122C mutation who developed pancreatic disease. Calcifications had developed in 5 (62.5%) at a mean age of 35.8 years (range: 14-56 years). Five (62.5%) developed changes in the pancreatic ducts at a mean age of 44.2 years (range: 19-65 years). Two patients (25.0%) developed steatorrhea during the follow-up at 26 and 35 years of disease progression. Diabetes developed in five patients (62.5%) at a mean age of 41.4 years old (range: 22-53 years). Three of the patients analyzed (37.5%) developed pancreatic cancer at 59 years of age, 63 years of age and 70 years of age.

Conclusions: Penetrance of the R122C mutation is lower than that described for the R122H and N29I mutations, and there is a tendency toward a predominance of males with the R122C mutation who developed the phenotype of pancreatitis.
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May 2009

Deficiency of CARD8 is associated with increased Alzheimer's disease risk in women.

Dement Geriatr Cogn Disord 2008 8;26(3):247-50. Epub 2008 Oct 8.

Unidad de Genética Molecular, Marqués de Valdecilla University Hospital, Santander, Spain.

NF-kappaB, a major transcription factor controlling inflammation, is activated in Alzheimer's disease (AD) brains. CARD8 protein has been implicated in the suppression of NF-kappaB activity, but a truncating polymorphism (p.C10X, rs2043211) renders a non-functional CARD8 protein that gives rise to a more active NF-kappaB and an amplification of the inflammatory process. Apolipoprotein E (ApoE) epsilon4 allele, the major genetic risk factor of AD, is associated with hyperactivation of NF-kappaB and enhanced brain inflammation. In a case-control study in 300 AD patients and 300 healthy controls, we examined whether the CARD8 (p.C10X) polymorphism, independently or in concert with the ApoE epsilon4 allele, might predispose to AD. Women, but not men, carrying the CARD8 AA genotype (truncated protein) had a 2.39-fold higher risk of developing AD than subjects with the CARD8 TT genotype (full-length protein). This association with susceptibility to AD was independent of the ApoE epsilon4 allele.
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http://dx.doi.org/10.1159/000160956DOI Listing
January 2009

Mutation study of Spanish patients with hereditary hemorrhagic telangiectasia.

BMC Med Genet 2008 Aug 1;9:75. Epub 2008 Aug 1.

Centro de Investigaciones Biologicas, CSIC, Ramiro de Maeztu, 9, Madrid 28040, Spain.

Background: Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant and age-dependent vascular disorder characterised mainly by mutations in the Endoglin (ENG) or activin receptor-like kinase-1 (ALK1, ACVRL1) genes.

Methods: Here, we have identified 22 ALK1 mutations and 15 ENG mutations, many of which had not previously been reported, in independent Spanish families afflicted with HHT.

Results: We identified mutations in thirty-seven unrelated families. A detailed analysis of clinical symptoms was recorded for each patient analyzed, with a higher significant presence of pulmonary arteriovenous malformations (PAVM) in HHT1 patients over HHT2. Twenty-two mutations in ALK1 and fifteen in ENG genes were identified. Many of them, almost half, represented new mutations in ALK1 and in ENG. Missense mutations in ENG and ALK1 were localized in a tridimensional protein structure model.

Conclusion: Overall, ALK1 mutations (HHT2) were predominant over ENG mutations (HHT1) in our Spanish population, in agreement with previous data from our country and other Mediterranean countries (France, Italy), but different to Northern Europe or North America. There was a significant increase of PAVM associated with HHT1 over HHT2 in these families.
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http://dx.doi.org/10.1186/1471-2350-9-75DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2518546PMC
August 2008

NLRP2, an inhibitor of the NF-kappaB pathway, is transcriptionally activated by NF-kappaB and exhibits a nonfunctional allelic variant.

J Immunol 2007 Dec;179(12):8519-24

Unidad de Genetica Molecular, Hospital Universitario Marques de Valdecilla, Santander, Spain.

NLRP2 has been shown to inhibit the NF-kappaB signaling pathway, and thus may contribute to modulate the inflammatory response, where NF-kappaB plays a major role. In this study, we report that expression of NLRP2 is induced upon differentiation of CD34+ hemopoietic progenitors into granulocyte or monocyte/macrophages. We also found that NLRP2 was up-regulated following differentiation of mesenchymal stem cells toward adipocytes. Notably, stimulation of HEK293T cells with TNF-alpha or overexpression of the p65 subunit of NF-kappaB resulted in up-regulation of NLRP2 and the formation of NF-kappaB-NLRP2 promoter complexes. Moreover, ectopic expression of p65 but not of other transcriptional regulators induced transactivation of the NLRP2 promoter. Thus, NLRP2 may control NF-kappaB activation through a regulatory loop. Nucleotide changes within the NACHT domain of other NLRP proteins have been associated with hereditary fever syndromes and chronic inflammatory diseases. We identified five single nucleotide polymorphisms present in the NACHT domain of NLRP2 by sequencing genomic DNA from 319 healthy controls. The frequencies of the rare alleles varied between 0.2 and 10%. Of note, one of these variants, I352S was unable to block the transcriptional activity of NF-kappaB and the formation of NF-kappaB-DNA-binding complexes following stimulation with TNF-alpha. Overall, our findings provide molecular insight into the expression of NLRP2 by NF-kappaB and suggest that a polymorphism within the NACHT domain of NLRP2 may contribute to the amplification of inflammatory responses due to a reduction of inhibitory signals on the NF-kappaB pathway.
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http://dx.doi.org/10.4049/jimmunol.179.12.8519DOI Listing
December 2007

Deficiency of the NF-kappaB inhibitor caspase activating and recruitment domain 8 in patients with rheumatoid arthritis is associated with disease severity.

J Immunol 2007 Oct;179(7):4867-73

Unidad de Genetica Molecular, Hospital Universitario Marques de Valdecilla, Santander, Spain.

Caspase activating and recruitment domain 8 (CARD8) potently inhibits NF-kappaB signaling, which plays a key role in inflammation, and may contribute to avoid a pathologic activation of NF-kappaB; however, the transcriptional mechanisms regulating CARD8 expression and the relevance of this protein in inflammatory diseases are poorly understood. We found a NF-kappaB-binding element within the human CARD8 promoter that was required for transcriptional activity in response to TNF-alpha and the p65 subunit of NF-kappaB. Moreover, TNF-alpha and overexpression of p65 induced the formation of NF-kappaB-CARD8 promoter complexes. Thus, CARD8 may control NF-kappaB activation through a regulatory loop. To study the relevance of CARD8 in chronic inflammatory disorders, we functionally characterized a deleterious polymorphism (p.C10X) and studied its association with rheumatoid arthritis (RA). Transfection of cell lines with the allelic variants of CARD8 revealed that full-length (CARD8-L) but not truncated (CARD8-S) protein inhibits NF-kappaB transcriptional activity, and abrogates the binding of NF-kappaB to its consensus site. Furthermore, in contrast to the full-length protein, CARD8-S did not modify the expression of NF-kappaB target genes (cIAP, A1), in response to TNF-alpha. We analyzed the p.C10X polymorphism in 200 patients with RA, and found that homozygous carriers of the CARD8-S allele have higher disease activity score (p = 0.014), more extra-articular manifestations (p = 0.03), and a lower probability of clinical remission (p = 0.03) than the CARD8-L allele carriers. Overall, our findings provide molecular insight into the expression of CARD8 by NF-kappaB, and suggest that a deleterious polymorphism of CARD8 may help predict the severity of RA.
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http://dx.doi.org/10.4049/jimmunol.179.7.4867DOI Listing
October 2007

Poly (ADP-ribose) polymerase-1 (PARP-1) genetic variants are protective against Parkinson's disease.

J Neurol Sci 2007 May 23;256(1-2):68-70. Epub 2007 Mar 23.

Service of Neurology, University Hospital Marqués de Valdecilla (University of Cantabria), Santander, Spain.

Poly (ADP-ribose) polymerase-1 (PARP-1) is involved in crucial pathogenic events in Parkinson's disease (PD). We studied the effect of promoter variations of PARP-1 gene on the risk for PD in a case-control association study comprising 146 PD patients and 161 controls from Northern Spain. Three polymorphisms from the promoter region of PARP-1 gene were analyzed: -410C/T, -1672G/A, and a (CA)n microsatellite. A protective effect against PD was found for heterozygosity at (-410) (OR 0.44) and (CA)n microsatellite (OR 0.53) polymorphisms, and heterozygosity at (-1672) polymorphism delayed by 4 years on the onset age of PD. Variations in the regulatory region of PARP-1 gene might modify the risk for PD.
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http://dx.doi.org/10.1016/j.jns.2007.02.008DOI Listing
May 2007

Identification of c-Kit gene mutations in patients with polycythemia vera.

Leuk Res 2006 Oct 7;30(10):1325-6. Epub 2006 Feb 7.

Imatinib mesylate has recently been reported to have clinical activity in the treatment of polycythemia vera (PV), suggesting the involvement of one of the kinases targeted by this inhibitor, including c-Kit and PDGFR. Activating c-Kit mutations have been identified in patients with mastocytosis and other myeloid disorders such as acute myeloid leukemia. Thus, we wanted to analyze the presence of mutations of c-Kit in polycythemia vera patients. We found that 7 out of 20 patients carried missense mutations in the c-Kit gene whereas no sequence variation was detected in 15 healthy controls.
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http://dx.doi.org/10.1016/j.leukres.2005.12.020DOI Listing
October 2006

LRRK2 G2019S is a common mutation in Spanish patients with late-onset Parkinson's disease.

Neurosci Lett 2006 Mar 18;395(3):224-6. Epub 2005 Nov 18.

Service of Neurology, University Hospital Marqués de Valdecilla, University of Cantabria, 39008 Santander, Spain.

Mutations in the leucine-rich repat kinase 2 (LRRK2) gene have been shown to cause both autosomal dominant and sporadic Parkinson's disease (PD). The common G2019S mutation shows wide geographical distribution while R1441G has been only reported in Northern Spain. The overall frequency of these mutations remains to be established. To determine the prevalence of G2019S and R1441G mutations in our population of Cantabria (Northern Spain), we recruited 105 consecutive PD patients and 310 controls and conducted genetic analysis of these mutations. G2019S was detected in eight late-onset patients (7.6%). Five of them had no relevant family history. R1441G was not detected in any of our study subjects. The prevalence of G2019S mutation in unselected late-onset PD patients might be higher than previously reported: 3/16 (18.7%) of familial PD and 5/82 (6.1%) of sporadic PD.
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http://dx.doi.org/10.1016/j.neulet.2005.10.083DOI Listing
March 2006

Imatinib inhibits proliferation of Ewing tumor cells mediated by the stem cell factor/KIT receptor pathway, and sensitizes cells to vincristine and doxorubicin-induced apoptosis.

Clin Cancer Res 2004 Jan;10(2):751-61

Department of Histology and Pathology, School of Medicine-Universidad de Navarra, Pamplona, Spain.

Purpose And Experimental Design: The stem cell factor/KIT receptor loop may represent a novel target for molecular-based therapies of Ewing tumor. We analyzed the in vitro impact of KIT blockade by imatinib in Ewing tumor cell lines.

Results: KIT expression was detected in 4 of 4 Ewing tumor cell lines and in 49 of 110 patient samples (44.5%) by immunohistochemistry and/or Western blot analysis. KIT expression was stronger in Ewing tumors showing EWS-FLI1 nontype 1 fusions. Despite absence of c-kit mutations, constitutive and ligand-inducible phosphorylation of KIT was found in all tumor cell lines, indicating an active receptor. Treatment with KIT tyrosine kinase inhibitor imatinib (0.5-20 micro M) induced down-regulation of KIT phosphorylation and dose response inhibition of cell proliferation (IC(50), 12-15 micro M). However, imatinib administered alone at doses close to IC(50) for growth inhibition (10 micro M) did not induce a significant increase in apoptosis. We then analyzed if blockade of KIT loop through imatinib (10 micro M) was able to increase the antitumor in vitro effect of doxorubicin (DXR) and vincristine (VCR), drugs usually used in Ewing tumor treatment. Addition of imatinib decreased in 15-20 and 15-36% of the proliferative rate of Ewing tumor cells exposed to DXR and VCR, respectively, and increased in 15 and 30% of the apoptotic rate of Ewing tumor cells exposed to the same drugs.

Conclusions: Inhibition of Ewing tumor cell proliferation by imatinib is mediated through blockade of KIT receptor signaling. Inhibition of KIT increases sensitivity of these cells to DXR and VCR. This study supports a potential role for imatinib in the treatment of Ewing tumor.
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http://dx.doi.org/10.1158/1078-0432.ccr-0778-03DOI Listing
January 2004

Interaction of the H63D mutation in the hemochromatosis gene with the apolipoprotein E epsilon 4 allele modulates age at onset of Alzheimer's disease.

Dement Geriatr Cogn Disord 2003 ;15(3):151-4

Unit of Neurology, 'Marqués de Valdecilla' University Hospital, University of Cantabria, Spain.

The H63D mutation in the hemochromatosis gene (HFE) has recently been considered as a risk factor in Alzheimer's disease (AD) with advancing age at onset of the disease, independently of the apolipoprotein E (ApoE) epsilon4 allele effect. We examined the distribution of the H63D mutation and ApoE genotypes as a function of age at AD onset in 328 patients with sporadic AD. Our data show that the mutant H63D allele potentially interacts with the ApoE epsilon4 allele to significantly reduce age at onset of AD compared to ApoE epsilon4 carriers alone, but has no effect on age at onset in ApoE epsilon4 non-carriers.
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http://dx.doi.org/10.1159/000068480DOI Listing
July 2003

Host recognition of bacterial muramyl dipeptide mediated through NOD2. Implications for Crohn's disease.

J Biol Chem 2003 Feb 4;278(8):5509-12. Epub 2003 Jan 4.

Department of Pathology and Comprehensive Cancer Center, The University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.

NOD2, a protein associated with susceptibility to Crohn's disease, confers responsiveness to bacterial preparations of lipopolysaccharide and peptidoglycan, but the precise moiety recognized remains elusive. Biochemical and functional analyses identified muramyl dipeptide (MurNAc-L-Ala-D-isoGln) derived from peptidoglycan as the essential structure in bacteria recognized by NOD2. Replacement of L-Ala for D-Ala or D-isoGln for L-isoGln eliminated the ability of muramyl dipeptide to stimulate NOD2, indicating stereoselective recognition. Muramyl dipeptide was recognized by NOD2 but not by TLR2 or co-expression of TLR2 with TLR1 or TLR6. NOD2 mutants associated with susceptibility to Crohn's disease were deficient in their recognition of muramyl dipeptide. Notably, peripheral blood mononuclear cells from individuals homozygous for the major disease-associated L1007fsinsC NOD2 mutation responded to lipopolysaccharide but not to synthetic muramyl dipeptide. Thus, NOD2 mediates the host response to bacterial muropeptides derived from peptidoglycan, an activity that is important for protection against Crohn's disease. Because muramyl dipeptide is the essential structure of peptidoglycan required for adjuvant activity, these results also have implications for understanding adjuvant function and effective vaccine development.
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http://dx.doi.org/10.1074/jbc.C200673200DOI Listing
February 2003

Induction of Nod2 in myelomonocytic and intestinal epithelial cells via nuclear factor-kappa B activation.

J Biol Chem 2002 Nov 22;277(44):41701-5. Epub 2002 Aug 22.

Unidad de Genetica Molecular, Hospital Universitario Marques de Valdecilla, 39008 Santander, Spain.

Nod2, a member of the Apaf1/Nod protein family, confers responsiveness to bacterial products and activates NF-kappaB, a transcription factor that plays a central role in innate immunity. Recently, genetic variation in Nod2 has been associated with susceptibility to Crohn's disease. Here, we report that expression of Nod2 is induced upon differentiation of CD34(+) hematopoietic progenitor cells into granulocyte or monocyte/macrophages. In peripheral blood cells, the highest levels of Nod2 were observed in CD14(+) (monocytes), CD15(+) (granulocytes), and CD40(+)/CD86(+) (dendritic cells) cell populations. Notably, stimulation of myeloblastic and epithelial cells with bacterial lipopolysaccharide or TNFalpha resulted in up-regulation of Nod2. A search for consensus sites within the Nod2 promoter revealed a NF-kappaB binding element that was required for transcriptional activity in response to TNFalpha. Moreover, ectopic expression of p65 induced transactivation, whereas that of dominant-negative IkappaBalpha blocked the transcriptional activity of the Nod2 promoter. Upon stimulation with TNFalpha or lipopolysaccharide, both p50 and p65 subunits of NF-kappaB were bound to the Nod2 promoter. Thus, Nod2 expression is enhanced by proinflammatory cytokines and bacterial components via NF-kappaB, a mechanism that may contribute to the amplification of the innate immune response and susceptibility to inflammatory disease.
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http://dx.doi.org/10.1074/jbc.M206473200DOI Listing
November 2002