Secretory expression, purification and functional characterization of 17β-hydroxysteroid dehydrogenase type 1 from mammalian HEK293T cells

Western blot analyses of various hamster tissues reveal high levels of expression of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in adrenal and liver, and moderate levels of expression in kidney. The expression in liver is sexually dimorphic; very high levels of protein are observed in adult male liver but very low levels are seen in the female liver. Three distinct cDNAs encoding isoforms of 3 beta-HSD were isolated from hamster cDNA libraries. The type 1 isoform is a high-affinity dehydrogenase/isomerase expressed in adrenal and male kidney. The type 2 isoform is also a high-affinity dehydrogenase/isomerase expressed in kidney and male liver. The type 3 enzyme is a 3-ketosteroid reductase expressed predominantly in kidney. Sequencing of the clones showed that all three are structurally very similar, although types 1 and 2 share the greatest degree of similarity. Immunohistochemical staining for 3 beta-HSD in the adrenal was found throughout the adrenal cortex. In the kidney staining was confined to tubules, and in the liver, heavy staining was found in hepatocytes. The cloning of cDNAs for 3 beta-HSD from the liver and kidney should help in elucidating the function of this enzyme in these tissues.

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Functional characterization of naturally occurring NR3C2 gene mutations in Italian patients suffering from pseudohypoaldosteronism type 1

Acta Endocrinologica ◽

10.1530/eje.1.02330 ◽

2007 ◽

Vol 156 (2) ◽

pp. 249-256 ◽

Cited By ~ 17

Author(s):

Antonio Balsamo ◽

Alessandro Cicognani ◽

Monia Gennari ◽

Wolfgang G Sippell ◽

Soara Menabò ◽

...

Keyword(s):

Receptor Gene ◽

Functional Characterization ◽

Clinical Signs ◽

Gene Mutations ◽

Ethnic Origin ◽

Snp Markers ◽

Italian Population ◽

Pseudohypoaldosteronism Type

Objective: The renal form of pseudohypoaldosteronism type 1 (PHA1) is a rare disease caused by mutations in the human mineralocorticoid receptor gene (NR3C2). Design: Aim of the study was to analyze the NR3C2 gene in three Italian patients with clinical signs of renal PHA1 and to evaluate the distribution of the -2G > C, c.538A > G, and c.722C > T single nucleotide polymorphism (SNP) pattern in the PHA1 patients and in 90 controls of the same ethnic origin. Methods: Analysis of the NR3C2 gene sequence and of the polymorphic SNP markers. Functional characterization of the detected novel NR3C2 mutations utilizing aldosterone-binding assays and reporter gene transactivation assays. Results: One novel nonsense (Y134X) and one novel frameshift (2125delA) mutation were detected. They exhibited no aldosterone binding and no transactivation abilities. No mutation was detected in the third patient. Haploinsufficiency of NR3C2 was ruled out by microsatellite analysis in this patient. The c.722T SNP was detected in 97% of alleles in the Italian population which is significantly different from the general German or US population. Conclusions: Molecular analysis of the NR3C2 gene in PHA1 patients is warranted to detect novel mutations in order to clarify the underlying genetic cause, which may extend the insight into relevant functional regions of the hMR protein. The effect the different distribution of the c.722T SNP is not clear to date. Further studies are necessary to provide evidence as to a possible advantage of a less sensitive hMR in southern countries.

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