title: Reduced number of CFTR molecules in erythrocyte plasma membrane of cystic fibrosis patients.
abstract: Cystic fibrosis (CF), the most common genetic disease among Caucasians, is caused by mutations in the gene encoding CFTR (cystic fibrosis transmembrane conductance regulator). The most frequent mutation, DeltaF508, results in protein misfolding and, as a consequence, prevents CFTR from reaching its final location at the cell surface. CFTR is expressed in various cell types including red blood cells. The functional role of CFTR in erythrocytes is still unclear. Since the number of CFTR copies in a single erythrocyte of healthy donors and CF patients with a homozygous DeltaF508 mutation is unknown, we counted CFTR, localized in erythrocyte plasma membrane, at the single molecule level. A novel experimental approach combining atomic force microscopy with quantum-dot-labeled anti-CFTR antibodies, used as topographic surface markers, was employed to detect individual CFTR molecules. Analysis of erythrocyte plasma membranes taken from healthy donors and CF patients with a homozygous DeltaF508 mutation reveals mean (SEM) values of 698 (12.8) (n=542) and 172 (3.8) (n=538) CFTR molecules per red blood cell, respectively. We conclude that erythrocytes reflect the CFTR status of the organism and that quantification of CFTR in a blood sample could be useful in the diagnosis of CFTR related diseases.
authors.affiliation: Institute of Physiology II, University of Muenster, and Department of Pediatrics, University Hospitals of Muenster, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Lange
authors.forename: Pia
authors.initials: P
authors.lastname: Jungmann
authors.forename: Johannes
authors.initials: J
authors.lastname: Haberle
authors.forename: Sabine
authors.initials: S
authors.lastname: Falk
authors.forename: Angelika
authors.initials: A
authors.lastname: Duebbers
authors.forename: Reimer
authors.initials: R
authors.lastname: Bruns
authors.forename: Andreas
authors.initials: A
authors.lastname: Ebner
authors.forename: Peter
authors.initials: P
authors.lastname: Hinterdorfer
authors.forename: Hans
authors.initials: H
authors.lastname: Oberleithner
authors.forename: Hermann
authors.initials: H
authors.lastname: Schillers
mesh_terms: D000906:Antibodies / Q000276:immunology; D002462:Cell Membrane / Q000737:chemistry / Q000648:ultrastructure; D003550:Cystic Fibrosis / Q000175:diagnosis*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000032:analysis*; D004910:Erythrocyte Membrane / Q000737:chemistry* / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D018625:Microscopy, Atomic Force / Q000379:methods; D045663:Quantum Dots
chemical_list: D000906:Antibodies; D019005:Cystic Fibrosis Transmembrane Conductance Regulator