| dc.description.abstract | Epidemiological evidence suggests higher incidence and severity of asthma in pre-menopausal women and aging men, suggesting a role of sex steroids, especially estrogen. In this regard, it is not clear whether specific estrogen receptors (ERα and ERβ) play differential roles or whether there is any imbalance in their normal signaling during asthma. Airway smooth muscle (ASM) cell is of contractile phenotype which is involved in contractions and airway hyperresponsiveness. Therefore, this research focused to understand ER signaling in the context of airway hyperresponsiveness and bridge the gaps in knowledge about the role of ERs in human ASM cells.
The first aim demonstrate the long-term differential signaling of ERs in the regulation of [Ca2+]i handling in the human ASM. It was found that ERα activation increases the [Ca2+]i response in baseline conditions, while ERβ activation has neutral effect. Moreover, the differential signaling of ERs is more evident in asthma or inflammation where ERβ activation decreases the [Ca2+]i response in the presence of inflammation while ERα increases it. Further elucidation of the mechanisms of their signaling on [Ca2+]i suggests that ERβ results in decreased [Ca2+]i response through increased SERCA2 expression and function, inhibition of pathways involved in activating the voltage gated LTCC and maintenance of the morphology of mitochondria.
In the next aim, it was found that ERβ causes a potentiation of the activity of β2-AR which leads to an increase in cAMP. Also, ERβ is found to be involved in dephosphorylation of contractile apparatus ultimately leading to bronchodilation. Presenting a contrasting picture, ERα causes an increase in pro-contractile machinery such as RhoA activity and phospho-MYPT leading to increased overall contractility in ASM cells.
To confirm these in vitro findings in the presence of other structural and immune cells involved in inflammation, I have further evaluated the ex vivo and in vivo roles of ER signaling in airways. Interestingly, ERβ was found to be protective for the airways while ERα further aggravated the contractility of the airways. These novel findings of ER signaling in the context of contractile mechanisms of the airways can be utilized in designing novel therapeutics for bronchodilation. | en_US |
