Multidrug resistance protein-6 (MRP6) in human dermal fibroblasts. Comparison between cells from normal subjects and from Pseudoxanthoma elasticum patients

Boraldi, Federica; Quaglino, Daniela; Croce, Maria Antonietta; Fernandez, M. I. Garcia; Tiozzo, Roberta; Gheduzzi, Dealba; Bacchelli, Barbara; Ronchetti, Ivonne Pasquali

doi:10.1016/j.matbio.2003.09.001

Cited by 34 publications

(30 citation statements)

References 30 publications

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“…However, little is known about the mineralization process and in particular what may induce elastic fibres to mineralise in PXE. It can be hypothesize that ABCC6/MRP6 deficiency would induce retention of cellular products which affect fibroblast metabolism (Boraldi et al, 2003) causing, as final consequence, extracellular matrix alterations (Neldner and Struk, 2002;Gheduzzi et al, 2003). Therefore, the relevant heterogeneity in clinical manifestations between relatives may suggest that, apart from PXE causative mutations, other genes and/or metabolic pathways that may have overall influence on the clinical expression of the disorder, as also suggested in a 20% of beta-thalassemia patients with PXE-like alterations (Baccarani-Contri et al, 2001).…”

Section: Genotype-phenotype Correlationmentioning

confidence: 99%

ABCC6 mutations in Italian families affected by pseudoxanthoma elasticum (PXE)

et al. 2004

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Pseudoxanthoma elasticum (PXE) is a genetic disorder, characterized by cutaneous, ocular and cardiovascular clinical symptoms, caused by mutations in a gene (ABCC6) that encodes for MRP6 (Multidrug Resistance associated Protein 6), an ATP-binding cassette membrane transporter. The ABCC6 gene was sequenced in 38 unrelated PXE Italian families. The mutation detection rate was 82.9%. Mutant alleles occurred in homozygous, compound heterozygous and heterozygous forms, however the great majority of patients were compound heterozygotes. Twenty-three different mutations were identified, among which 11 were new. Fourteen were missense (61%); five were nonsense (22%); two were frameshift (8.5%) and two were putative splice site mutations (8.5%). The great majority of mutations were located from exon 24 to 30, exon 24 being the most affected. Among the others, exons 9 and 12 were particularly involved. Almost all mutations were located in the intracellular site of MRP6. A positive correlation was observed between patient's age and severity of the disorder, especially for eye alterations. The relevant heterogeneity in clinical manifestations between patients with identical ABCC6 mutations, even within the same family, seems to indicate that, apart from PXE causative mutations, other genes and/or metabolic pathways might influence the clinical expression of the disorder.

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Section: Genotype-phenotype Correlationmentioning

confidence: 99%

ABCC6 mutations in Italian families affected by pseudoxanthoma elasticum (PXE)

et al. 2004

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“…31 The principle of the assay in brief: cells were loaded with 0.1 mM of the nonfluorescent membrane-permeable calcein-acetoxymethyl (caAM) ester for 30 min at 371C. The AM ester is cleaved by Silencing of ABCC6/MRP6 Expression Using ABCC6-Specific Small-Interfering RNA ABCC6-specific small-interfering RNA (siRNA) and FAMlabeled control siRNA oligonucleotides were purchased from Ambion (Cambridgeshire, UK; Table 3).…”

Section: Measurement Of Mrp Efflux Activity By Flow Cytometrymentioning

confidence: 99%

“…MRPs are active in dermal fibroblasts as these cells exhibit a MRP efflux activity that can be blocked by specific inhibitors known to interfere with MRP function. [29][30][31] Furthermore, it was reported that PXE fibroblasts have a reduced MRP transporter activity compared to normal dermal fibroblasts. 31 Beside MRP6, other MRPs have also been reported to be associated with human diseases.…”

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Gene expression profiling of ABC transporters in dermal fibroblasts of pseudoxanthoma elasticum patients identifies new candidates involved in PXE pathogenesis

Hendig

Langmann

Kocken

et al. 2008

Laboratory Investigation

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Mutations in the ABCC6 gene, encoding the multidrug resistance-associated protein 6 (MRP6), cause pseudoxanthoma elasticum (PXE). This heritable disorder leads to pathological alterations in connective tissues. The implication of MRP6 deficiency in PXE is still unknown. Moreover, nothing is known about a possible compensatory expression of other ATP binding-cassette (ABC) transporter proteins in MRP6-deficient cells. We investigated the gene expression profile of 47 ABC transporters in human dermal fibroblasts of healthy controls (n ¼ 2) and PXE patients (n ¼ 4) by TaqMan low-density array. The analysis revealed the expression of 37 ABC transporter genes in dermal fibroblasts. ABCC6 gene expression was not quantifiable in fibroblasts derived from PXE patients. Seven genes (ABCA6, ABCA9, ABCA10, ABCB5, ABCC2, ABCC9 and ABCD2) were induced, whereas the gene expression of one gene (ABCA3) was decreased, comparing controls and PXE patients (with at least twofold changes). We reanalyzed the gene expression of selected ABC transporters in a larger set of dermal fibroblasts from controls and PXE patients (n ¼ 6, each). Reanalysis showed high interindividual variability between samples, but confirmed the results obtained in the array analysis. The gene expression of ABC transporter genes, as well as lineage markers of PXE, was further examined after inhibition of ABCC6 gene expression by using specific small-interfering RNA. These experiments corroborated the observed gene expression alterations, most notably in the ABCA subclass (up to fourfold, Po0.05). We therefore conclude that MRP6-deficient dermal fibroblasts exhibit a distinct gene expression profile of ABCA transporters, potentially to compensate for MRP6 deficiency. Moreover, our results point to a function for ABCC6/MRP6 in sterol transport, as sterols are preferential regulators of ABCA transporter activity and expression. Further studies are now required to uncover the role of ABCA transporters in PXE.

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“…What could be the significance and importance of the presence of at least part of MRP6 in the endoplasmic reticulum of mesenchymal cells have not been investigated. However, in the light of these observations, changes in membrane transport properties described in PXE cultured fibroblasts (Boraldi et al, 2003) would seem likely the result of the high level of reactive oxygen species (ROS) on the structural organization of cell membranes (Boraldi et al, 2009) and consequently on cell permeability. It has been in fact demonstrated in vitro (Pasquali-Ronchetti et al, 2006) and in vivo (Garcia-Fernandez et al, 2008) that PXE is characterized by an altered redox balance.…”

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confidence: 99%