A subcellular atlas of AKT as a predictive tool of its physiological and pathological roles

ANTONELLA VILA; ALEJANDRO COLMAN-LERNER; MATÍAS BLAUSTEIN

Simposio; Simposio Argentino de Jóvenes Investigadores en Bioinformática; 2022

Regulation of protein kinase AKT activity is associated with a diversity of processes, including cell metabolism, proliferation, differentiation and survival, as well as pathological processes such as viral infection and cancer development. AKT is a therapeutic target for cancer treatment and it is known to be regulated through numerous posttranslational modifications (PTMs) as well as to be recruited to different subcellular compartments. However, little is known about how a cell determines which substrates and functions AKT should regulate. Our hypothesis is that the profile of AKT PTMs can determine the subcellular localization of AKT, and vice versa, thus establishing the subset of AKT target substrates and the set of functions that AKT displays in response to each stimulus and each particular cellular context. The aim of this work is to develop an atlas of AKT subcellular localizations as a predictive tool of AKT physiological and pathological functions using bioinformatic and experimental tools. Using a combination of different bioinformatic resources, we performed an analysis of the AKT interactome, which allows us to explain and even predict the functional and subcellular code of AKT.The analysis of the AKT interactome showed an endomembrane system-enriched domain, associated with biological processes such as cell proliferation, cell death, cellular response to stress, and autophagy, and associated with different types of cancer. We experimentally tested these predictions by performing quantitative analysis of fluorescence microscopy images and we found a tight coregulation of Akt recruitment to endoplasmic reticulum, Golgi and lysosome membranes. Particularly, we show that Akt is recruited to these membranes in response to stressing signals like serum starvation and oxidative stress, in association with biological processes such as autophagy and cell death, as predicted.Furthermore, our bioinformatic analysis revealed a nuclear speckle-enriched domain on the AKT interactome, associated with RNA splicing, and diseases related to congenital malformations. However, to date, AKT has not been reported to be recruited to this subcellular compartment. Indeed, fluorescence microscopy experiments showed that both AKT and phosphorylated AKT substrates colocalize with nuclear speckles.These results shed light into the role of AKT recruitment to different cell compartments and the specific targets and physiological as well as pathological functions triggered by AKT in different subcellular localizations.