β-estradiol Affected cAMP-signaling Molecule Expression in a Parotid Cell Line

Objectives: Women tend to have more caries than men. One explanation for this phenomenon is that women secret less saliva. Salivary glands are known to express receptors for sex hormones, including estrogen receptors. Among the three estrogen receptors, ERα and ERβ have been shown to be expressed in both acinar and ductal cells of salivary glands, while the expression of GPR30 is still unclear. In either lymphoid organs or endothelial cells, estrogen is shown to interact with β-adrenergic stimulation, leading to immunomodulation or changes in vasoconstriction, respectively. β-adrenergic stimulation and its downstream cAMP signaling activation are known to modulate fluid secretion caused by the parasympathetic innervation. When the interaction of the cAMP signaling and estrogen is still unclear in the salivary glands, we proposed the expression of the cAMP-signaling molecules is changed by estrogen.
Methods: The mouse parotid cell line, Par-C10, was cultured and lysed. After gel electrophoresis and lysate protein transfer, Western blot analyses were performed to identify of the expression of three receptors for estrogen: ERα, ERβ and GPR30. Cells were also treated by various concentrations (10^-12 – 10^-4 M) of β-estradiol for 24 hours, and then lysed for Western blot analyses of cAMP signaling molecules, including β1-adrenergic receptors (β1-AR), β2-adrenergic receptors (β2-AR), catalytic subunits of protein kinase A (PKA), A-kinase anchoring protein 5 (AKAP5).
Results: All three types of estrogen receptors, ERα, ERβ and GPR30, were identified in cell lysates of Par-C10 cells. Treatment of β-estradiol increased in the expression of β2-AR, PKA and AKAP5 in Par-C10 cells. However, only the expression of AKAP5 was statistically different.
Conclusions: β-estradiol increased the expression of AKAP5, the scaffolding protein of PKA. How this effect influences the cAMP signaling pathway in Par-C10 cells, and whether this interaction affects exocrine physiology of salivary cells require further investigation.