Yazar "Erdem, Beril" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Identification of a Novel Deletion in AVP-NPII Gene in a Patient with Central Diabetes Insipidus
    (Assoc Clinical Scientists, 2015) Deniz, Ferhat; Acar, Ceren; Saglar, Emel; Erdem, Beril; Karaduman, Tugce; Yonem, Arif; Cagiltay, Eylem
    Central Diabetes Insipidus (CDI) is caused by a deficiency of antidiuretic hormone and characterized by polyuria, polydipsia and inability to concentrate urine. Our objective was to present the results of the molecular analyses of AVP-neurophysin II (AVP-NPII) gene in a large familial neurohypophyseal (central) DI pedigree. A male patient and his family members were analyzed and the prospective clinical data were collected. The proband applied to hospital for eligibility to be a recruit in Armed Forces. The patient had severe polyuria (20 L/day), polydipsia (20.5 L/day), fatique, and deep thirstiness. CDI was confirmed with the water deprivation-desmopressin test according to an increase in urine osmolality from 162 mOsm/kg to 432 mOsm/kg after desmopressin acetate injection. To evaluate the coding regions of AVP-NPII gene, polymerase chain reactions were performed and amplified regions were submitted to direct sequence analysis. We detected a heterozygous three base pair deletion at codon 69-70 (207_209delGGC) in exon 2, which lead to a deletion of the amino acid alanine. A three-dimensional protein structure prediction was shown for the deleted AVP-NPII and compared with the wild type. The three base pair deletion may yield an abnormal AVP precursor in neurophysin moiety, but further functional analyses are needed to understand the function of the deleted protein.
  • Küçük Resim Yok
    Öğe
    Investigation of Fibrillar Aggregates Formed by Pathogenic Pre-pro-vasopressin Mutants that Cause ADNDI
    (Endocrine Soc, 2025) Vaizoglu, Refika Dilara; Erdem, Beril; Gul, Mehmet; Acar, Ceren; Ozdemirel, Huseyin Ozgur; Ozer, Emel Saglar; Mergen, Hatice
    Context: Aggregations of unfolded or misfolded proteins, both inside and outside cells, are implicated in numerous diseases, collectively known as amyloidosis. Particularly, autosomal dominant neurohypophyseal diabetes insipidus (ADNDI) is a rare disease caused by mutations in the AVPNPII gene, leading to the inability to secrete arginine vasopressin. These misfolded proteins accumulate within the endoplasmic reticulum (ER), causing cellular dysfunction. Objective: This study aimed to investigate the formation of amyloid-like aggregates within the cell resulting from misfolded mutant precursor proteins, which induce disulfide-linked oligomers due to the G45C, 207_209delGGC, G88V, C98X, C104F, E108D-1, E108D-2 and R122H mutations identified by our group in the AVP-NPII gene of ADNDI patients. Methods: Deglycosylation studies were performed to analyze the glycosylation patterns of mutant protein precursors. The involvement of these precursors in the ER-related degradation pathway was studied by conducting protease inhibition experiments. Disulfide-linked oligomer analysis determined the oligomerization status of the mutant precursors. Immunofluorescence and electron microscopy studies provided evidence of aggregate structures in the ER lumen. In vitro studies involved bacterial expression and fibril formation in Escherichia coli (E. coli). Results: Our findings demonstrated that the N-glycan structure of mutant precursors remains intact within the ER. Protease inhibition experiments indicated the involvement of these precursors in the ER-related degradation pathway. Disulfide-linked oligomer analysis revealed homo-oligomer structures in mutations. Immunofluorescence and electron microscopy studies confirmed the presence of aggregate structures in the ER lumen. In vitro studies showed that mutant precursors could form fibril structures in E. coli. Conclusion: Our study may support the idea that ADNDI belongs to the group of neurodegenerative diseases due to the formation of fibrillar amyloid aggregates in the cell.