title: Analysis of pseudoxanthoma elasticum-causing missense mutants of ABCC6 in vivo; pharmacological correction of the mislocalized proteins.
abstract: Mutations in the ABCC6 gene cause soft-tissue calcification in pseudoxanthoma elasticum (PXE) and, in some patients, generalized arterial calcification of infancy (GACI). PXE is characterized by late onset and progressive mineralization of elastic fibers in dermal, ocular, and cardiovascular tissues. GACI patients present a more severe, often prenatal arterial calcification. We have tested 10 frequent disease-causing ABCC6 missense mutants for the transport activity by using Sf9 (Spodoptera frugiperda) cells, characterized the subcellular localization in MDCKII (Madin-Darby canine kidney (cell line)) cells and in mouse liver, and tested the phenotypic rescue in zebrafish. We aimed at identifying mutants with preserved transport activity but with improper plasma membrane localization for rescue by the chemical chaperone 4-phenylbutyrate (4-PBA). Seven of the mutants were transport-competent but mislocalized in mouse liver. The observed divergence in cellular localization of mutants in MDCKII cells versus mouse liver underlined the limitations of this 2D in vitro cell system. The functionality of ABCC6 mutants was tested in zebrafish, and minimal rescue of the morpholino-induced phenotype was found. However, 4-PBA, a drug approved for clinical use, restored the plasma membrane localization of four ABCC6 mutants (R1114P, S1121W, Q1347H, and R1314W), suggesting that allele-specific therapy may be useful for selected patients with PXE and GACI.
authors.affiliation: Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Viola
authors.initials: V
authors.lastname: Pomozi
authors.affiliation: Department of Cell and Molecular Biology, John A Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Brampton
authors.affiliation: Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Krisztina
authors.initials: K
authors.lastname: Fülöp
authors.affiliation: Department of Cell and Molecular Biology, John A Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
authors.forename: Li-Hsieh
authors.initials: LH
authors.lastname: Chen
authors.affiliation: Department of Cell and Molecular Biology, John A Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
authors.forename: Ailea
authors.initials: A
authors.lastname: Apana
authors.affiliation: Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Qiaoli
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Jouni
authors.initials: J
authors.lastname: Uitto
authors.affiliation: Department of Cell and Molecular Biology, John A Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
authors.forename: Olivier
authors.initials: O
authors.lastname: Le Saux
authors.affiliation: Institute of Enzymology, RCNS, Hungarian Academy of Sciences, Budapest, Hungary. Electronic address: varadi@enzim.hu.
authors.forename: András
authors.initials: A
authors.lastname: Váradi
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000483:Alleles; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004285:Dogs; D006801:Humans; D007313:Insecta; D008099:Liver / Q000378:metabolism; D061985:Madin Darby Canine Kidney Cells; D051379:Mice; D008810:Mice, Inbred C57BL; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics*; D009154:Mutation; D020125:Mutation, Missense; D010641:Phenotype; D010654:Phenylbutyrates / Q000737:chemistry; D011487:Protein Conformation; D017510:Protein Folding; D011561:Pseudoxanthoma Elasticum / Q000235:genetics*; D015027:Zebrafish
chemical_list: D018528:ATP-Binding Cassette Transporters; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010654:Phenylbutyrates; C102029:ABCC6 protein, human; C504743:Abcc6 protein, mouse; C075773:4-phenylbutyric acid