Endocrine Abstracts

Calcium is important for physiological functioning in many tissues and is essential in mucus secretion and muscle contraction. Intracellular concentrations of calcium are regulated by calcium-related proteins such as TRPV4, TRPV6, CaBP-9k, NCX1, and PMCA1. In this study, the relationship between secretion of pulmonary mucus and calcium regulation was investigated. To confirm the effect of steroid hormones, immature mice were injected with estrogen (E2) or progesterone (P4) and mature mice were injected with dexamethasone (DEX). Subsequently, the location and expression of TRPV4, TRPV6, CaBP-9k, NCX1, and PMCA1 in lung tissue were examined. PAS staining was performed to investigate functional aspects of the protein expressions. There were no significant differences in calcium-related gene expressions in E2- and P4-treated mice, but TRPV4, NCX1, and PMCA1 were increased in DEX-treated mice and were recovered by RU486 treatment. This regulation is via the glucocorticoid receptor and is involved in the mucus secretion in the lung. TRPV4, TRPV6, CaBP-9k, NCX1, and PMCA1 were specifically expressed in Clara and alveolar type 2 cells of mouse lung. CC10, a marker of Clara cell, was decreased by DEX. In addition, mucin secretion, which is a functional aspect of this cell, was also decreased by DEX treatment. Control of calcium-related gene expression may affect the control of mucus secretion in the lung. Such a control mechanism can form the basis of studies into diseases such as inflammation due to mucus secretion abnormalities, coughing, and respiratory disorders and distress.