Browsing by Author "Fardella, C. E."

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    A de novo unequal cross-over mutation between CYP11B1 and CYP11B2 genes causes familial hyperaldosteronism type I
    (2010) Carvajal, C. A.; Stehr, C. B.; González, P. A.; Riquelme, E. M.; Montero, T.; Santos, M. J.; Kalergis, Alexis M.; Fardella, C. E.
    Familial hyperaldosteronism type I (FH-I) is an autosomal dominant disorder caused by an unequal cross-over of the gene encoding steroid 11β-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2), giving rise to a chimeric CYP11B1/CYP11B2 gene that displays aldosterone synthase activity regulated by ACTH instead of angiotensin II.To report an unprecedented case of a de novo unequal crossover mutation between CYP11B1 and CYP11B2 genes causing FH-I.The index case is a 45-yr-old Chilean male diagnosed with primary aldosteronism (PA). All family members were also studied: his biological parents, 1 brother, 6 sisters, 2 daughters, and 1 son. Plasma renin activity, serum aldosterone, and its ratio were measured in all patients. Genetic analyses were performed using long-extension PCR (XL-PCR), DNA sequencing and Southern blot methods.PA was diagnosed for the index case, 1 of his daughters, his son but not for his parents or siblings. XLPCR and Southern blotting demonstrated the presence of the chimeric CYP11B1/CYP11B2 gene solely in PA-affected subjects, suggesting a case of a de novo mutation. Sequence analysis showed the unequal cross-over CYP11B1/CYP11B2 at intron 2 (c.2600-273 CYP11B2). We also identified a polymorphism at the same intron (c.2600-145C>A CYP11B2) in the genome of the index case's father.We describe an unprecedented case of unequal cross-over mutation for the chimeric CYP11B1/CYP11B2 gene causing FH-I, which may be linked to a polymorphism in the index case's father germ line.
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    Immune System Alterations by Aldosterone During Hypertension: From Clinical Observations to Genomic and Non-Genomic Mechanisms Leading to Vascular Damage
    (2013) Munoz-Durango, N.; Barake, M. F.; Letelier, N. A.; Campino, C.; Fardella, C. E.; Kalergis, A. M.
    Hypertension is traditionally considered a disease in which elevated blood pressure contributes to inflammation and activation of the immune system, leading to cardiovascular injury and end-organ damage. Here, we discuss the effects of aldosterone on the immune system and aldosterone's contribution to vascular pathogenesis. Studies in human have suggested a broader role for aldosterone, beyond elevating blood pressure. Recent clinical data support the notion that aldosterone can directly alter the function of the immune system and cause vascular-damaging inflammation. Clinical observations have been reproduced in experimental models of hypertension, further supporting the idea that an aberrant immune response contributes to the onset of hypertension. Such studies have shown that myeloid cells are required to induce the disease and IL-17-producing CD4(+) T cells may contribute to maintaining aldosterone-mediated hypertension. In addition, regulatory T cells diminish the inflammatory damage caused by aldosterone during hypertension. This is a very active area of research that could lead to new therapeutic targets for treating hypertension.
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    New splicing mutation of MEN1 gene affecting the translocation of menin to the nucleous
    (2006) Tala, H. P.; Carvajal, C. A.; Gonzalez, A. A.; Garrido, J. L.; Tobar, J.; Solar, A.; Campino, C.; Arteaga, E.; Fardella, C. E.
    Multiple endocrine neoplasia type 1 (MEN1) is a syndrome inherited in an autosomal dominant trait caused by the inactivation of the tumor suppressor gene MEN1. Objective: To communicate a family with a new heterozygous germ line mutation in the intronic region of MEN1 gene and to study its influence in the menin expression. Patients and Methods: We studied 5 members of a family with symptomatic hyperparathyroidism (HIPT). One of them had also a neuroendocrine pancreatic tumor, and 2 had non-functional multinodular cortical adrenal hyperplasia compatible with the diagnosis of MEN1. After the mutation was identified, HSP9211 restriction enzyme was used to determine both zygosity and segregation of the mutation. RT-PCR from leukocyte's isolated mRNA and western blot from pancreatic tumor tissue were performed. In vitro studies were done in Chinese hamster ovary (CHO) cells transfected with reporter minigenes carrying the coding regions spanning exon (EX)-intron 9 and EX10 with the mutant and the wild type sequences. Results: We identified a heterozygous G-to-T substitution in the intron-EX junction (IVS9-1 G > T) of MEN1 gene in the index case and the family members. The mRNA from patient's leukocytes was larger (934 bp) in comparison to the normal transcript (717 bp). Immunoblot analysis demonstrated that wild type (67 kDa) and two additional mutant proteins (similar to 55 and similar to 90 kDa) were expressed in the pancreatic tissue. The in vitro study showed a 45% nuclear localization of the mutated menin signal and a 95% in the wild type protein. Conclusions: We identified a new intronic heterozygous germ line mutation (IVS9-1G > T) of MEN1 gene in a family affected by MEN1 syndrome. This mutation alters the splice acceptor site of intron 9 that promotes an incorrect splicing, generating aberrant proteins without the nuclear localization signals necessary for the normal menin translocation to the nucleus.