Purchase this article with an account.
Qian Wang, Abdul Hannan, Sungtae Yoon, Xin Zhang; PI3K cooperates with MAPK to regulate mTOR signaling during lacrimal gland development. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2617.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The PI3K-mTOR axis is a pivotal regulator of tissue growth and homeostasis, but its role in the lacrimal gland development is poorly understood. In this study, we combined mouse genetics and biochemical experiments to investigate the regulation and function of PI3K-mTOR in the lacrimal gland development.
We generated conditional knockout mouse lines using Le-Cre, which is specifically expressed in the lacrimal gland epithelium and linked to an IRES-GFP reporter. GFP fluorescence was used to visualize the structure of the lacrimal gland at different stages of development. Immunofluorescence was performed to further characterize the lacrimal gland phenotype. In order to decipher the regulatory network of PI3K-mTOR signaling, we performed RNA sequencing analysis of lacrimal gland epithelial tissues which was collected using laser capture microdissection. In addition, we established mouse embryonic fibroblast (MEF) cell model to corroborate our results in vitro. In all experimental conditions, heterozygous litter-mates carrying Le-Cre were used as control.
Conditional knockout of PI3K catalytic subunits p110α/β (p110 cko) completely abolished the lacrimal gland budding and caused reduction of MAPK signaling. Consistent with the interplay between PI3K and MAPK pathways, the p110 cko phenotypes were partially rescued by the constitutively active Mek1 (Mek1DD) which elevates the MAPK activity. Mechanistically, we showed that PI3K enhances MAPK signaling by promoting Ras activity via its Ras binding domain. We further demonstrated that PI3K and MAPK are both required for mTOR activity during the lacrimal gland budding. As a result, inactivation of the mTOR complex 1 reproduced the loss of lacrimal gland phenotype in the PI3K and MAPK deletion mutants.
During the lacrimal gland development, 1) PI3K cross-activates the MAPK signaling, 2) mTOR signaling is controlled by both PI3K and MAPK pathways.
This is a 2020 ARVO Annual Meeting abstract.
This PDF is available to Subscribers Only