PT  - JOURNAL ARTICLE
AU  - Karbian, Netanel
AU  - Eshed-Eisenbach, Yael
AU  - Tabib, Adi
AU  - Hoizman, Hila
AU  - Morgan, B. Paul
AU  - Schueler-Furman, Ora
AU  - Peles, Elior
AU  - Mevorach, Dror
TI  - Molecular pathogenesis of human CD59 deficiency
AID  - 10.1212/NXG.0000000000000280
DP  - 2018 Dec 01
TA  - Neurology Genetics
PG  - e280
VI  - 4
IP  - 6
4099  - http://ng.neurology.org/content/4/6/e280.short
4100  - http://ng.neurology.org/content/4/6/e280.full
SO  - Neurol Genet2018 Dec 01; 4
AB  - Objective To characterize all 4 mutations described for CD59 congenital deficiency.Methods The 4 mutations, p.Cys64Tyr, p.Asp24Val, p.Asp24Valfs*, and p.Ala16Alafs*, were described in 13 individuals with CD59 malfunction. All 13 presented with recurrent Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy, recurrent strokes, and chronic hemolysis. Here, we track the molecular consequences of the 4 mutations and their effects on CD59 expression, localization, glycosylation, degradation, secretion, and function. Mutants were cloned and inserted into plasmids to analyze their expression, localization, and functionality.Results Immunolabeling of myc-tagged wild-type (WT) and mutant CD59 proteins revealed cell surface expression of p.Cys64Tyr and p.Asp24Val detected with the myc antibody, but no labeling by anti-CD59 antibodies. In contrast, frameshift mutants p.Asp24Valfs* and p.Ala16Alafs* were detected only intracellularly and did not reach the cell surface. Western blot analysis showed normal glycosylation but mutant-specific secretion patterns. All mutants significantly increased MAC-dependent cell lysis compared with WT. In contrast to CD59 knockout mice previously used to characterize phenotypic effects of CD59 perturbation, all 4 hCD59 mutations generate CD59 proteins that are expressed and may function intracellularly (4) or on the cell membrane (2). None of the 4 CD59 mutants are detected by known anti-CD59 antibodies, including the 2 variants present on the cell membrane. None of the 4 inhibits membrane attack complex (MAC) formation.Conclusions All 4 mutants generate nonfunctional CD59, 2 are expressed as cell surface proteins that may function in non–MAC-related interactions and 2 are expressed only intracellularly. Distinct secretion of soluble CD59 may have also a role in disease pathogenesis.CIDP=chronic inflammatory demyelinating polyradiculoneuropathy; ER=endoplasmic reticulum; GBS=Guillain-Barré syndrome; MAC=membrane attack complex; PNH=paroxysmal nocturnal hemoglobinuria; SDS-PAGE=sodium dodecyl sulfate–polyacrylamide gel electrophoresis; WT=wild type