Functional evaluation of germline variants in the phosphodiesterase 2A (PDE2A) and 3A (PDE3A) genes in bilateral primary aldosteronism.

• Grant number: 24/18510-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: December 01, 2024
• End date: June 30, 2026
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Madson Queiroz Almeida
• Grantee: Jose Antonio Barbosa Lima Sobrinho
• Host Institution: Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
• Associated research grant: 19/15873-6 - Investigation of new genetic, clinical and pathological aspects of endocrine arterial hypertension, AP.TEM

Abstract

Primary aldosteronism (PA) is a condition characterized by the autonomous excessive secretion of aldosterone by the adrenal gland, not regulated by the renin-angiotensin-aldosterone system. PA is the most common cause of secondary hypertension and is associated with an increased cardiovascular risk. PA can be unilateral in 30-40% of cases or bilateral in 50-60% of cases. Familial PA is rare, affecting 1-5% of patients. Although bilateral PA is the most frequent cause of PH, few advances have been made in elucidating its genetic basis. Recently, we performed whole exome sequencing of 36 patients with bilateral PA with stage 3 or resistant hypertension and a diagnosis of hypertension before the age of 40 years. Rare germline variants were identified in the genes for phosphodiesterases 2A (PDE2A c.2469G>A / p.Ala823Ala) and 3A (PDE3A c.635T>G / p.Val212Gly) in 2 of the 36 (5.5%) of these patients. In a previous study by our group, a germline variant in PDE2A (c.1885A>G; p.Ile629Val) was identified in a patient with bilateral PA diagnosed at the age of 20 years. PDE2A was strongly expressed in hyperplastic areas and micronodules of adrenal hyperplasias. Additionally, strong expression of PDE2A was observed exclusively in the zona glomerulosa of normal adrenal glands. The synonymous variant identified in the PDE2A, despite being seemingly silent, is located at the last nucleotide of exon 28, near the canonical splicing site (donor) in IVS28. In silico predictions suggest pathogenicity with potential to cause skipping of the adjacent exon. The objective of this study is to perform in vitro functional studies of the germline variants in the PDE2A (c.2469G>A / p.Ala823Ala and c.1885A>G / p.Ile629Val) and PDE3A (c.635T>G / p.Val212Gly) genes in the adrenal tumor cell line NCI H295R-S2. Functional studies will include: cell culture, mutagenesis, transfection, minigene assays, RNA interference, real-time PCR, Western blot, measurement of PKA activity, and cell proliferation.