LOSS-OF-FUNCTION MUTATIONS IN ATP6V0A2 IMPAIR VESICULAR عنوان الوثيقة Document ( TRAFFICKING, ELASTIN DEPOSITION, AND CELL SURVIVAL Autosomal recessive cutis laxa type 2 (ARCL2), a syndrome of growth and developmental delay and redundant, inelastic skin, is caused by mutations in the a2 subunit of the vesicular ATPase H +-pump (ATP6V0A2). The goal of this study was to define the disease mechanisms that lead to connective tissue lesions in ARCL2. In a new cohort of 17 CL patients, DNA sequencing of ATP6V0A2 detected either homozygous or compound heterozygous mutations. A great degree of allelic and phenotypic heterogeneity was observed, with a missense mutation of a moderately conserved residue p.P87L leading to unusually mild disease. Abnormal N- and/or mucin type O-glycosylation was observed in all patients tested. Premature stop codon mutations led to decreased ATP6V0A2 mRNA levels by destabilizing the mutant mRNA via the nonsense-mediated decay pathway. Loss of ATP6V0A2 either by siRNA knockdown or in ARCL2 cells resulted distended Golgi sacs, accumulation of abnormal secretory vesicles, and multivesicular bodies. Immunostaining of ARCL2 cells showed abundant staining for tropoelastin in the Golgi, and other intracellular compartments, often associated with apoptotic nuclear morphology. TUNEL staining confirmed increased rates of apoptosis in ARCL2 cell cultures, and insoluble elastin assays showed significantly reduced deposition of elastin. Fibrillin-1 micorfibrils and secreted lysyl oxidase activity were normal in ARCL2 cells. We conclude that loss of function mutations in ATP6V0A2 lead to secretory defects that specifically impair tropoelastin trafficking and cell survival leading to the observed skin and connective tissue abnormalities in ARCL2. Online ISSN 1460-2083 - Print ISSN 0964-6906 Human Molecular Genetics 2010 Oxford University Press Oxford Journals 18 12 15 June 2009. )Title المستخلص )Abstract( )ISSN( ردمد اسم الدورية Journal ( )Name اسم الناشر (Publisher) المجلد )Volume( Issue ( العدد )Number سنة النشر Publishing ( )Year الصفحات ()Pages من: 2149 االسم األول للباحث إلى 2165 : (ع) جمانة ()E Jumana االسم األخير للباحث (ع) : األعمى ()E Al-Aama العنوان المملكة العربية السعودية – جدة – جامعة الملك عبد العزيز – قسم األمراض الوراثية Step3 تعبئة هذا النموذج لكل بحث لدى الدكتور وإرسالها إلى med.it@hotmail.comفي أسرع وقت