The cells of humans and vertebrate and invertebrate animals have a signaling pathway, called WNT dependent on the beta-catenin protein, which is fundamental for the development of embryos and for cell proliferation and tissue structuring. WNT dysregulation can cause embryo malformation and the development of a series of diseases, such as breast and cervical cancer.
A group of researchers from the Center for Medicinal Chemistry (CQMED), directed by professor Paulo Arruda, from Unicamp, discovered a way to regulate this route, according to an article published by Fapesp Research. Created with support from FAPESP through the Research Support Program in Partnership for Technological Innovation (PIES), CQMED is a unit of the Brazilian Industrial Research and Innovation Company (Embrapii) specialized in the area of biopharmaceuticals and pharmaceuticals. The unit is formed by researchers from the Center for Molecular Biology and Genetic Engineering and the Institute of Biology at the State University of Campinas (Unicamp), in partnership with the Structural Genomics Consortium (SGC). CQMED also has support from FAPESP, from CNPq and Capes through the National Institutes of Science and Technology program.
The results of the study, originating from a partnership between the SGC laboratories located at Unicamp, the universities of North Carolina, Chapel Hill, in the United States, Oxford, England, and Frankfurt, Germany, with other research institutions in the United States, United Kingdom and Japan, were published in the magazine Cell reports.
“Through a chemically synthesized compound that we developed in recent years, we were able to advance the understanding and regulate the WNT signaling pathway dependent on the beta-catenin protein,” he said. Roberta Regina Ruela de Souza, postdoctoral fellow at SGC-Unicamp with FAPESP scholarship and one of the first authors of the study, FAPESP Agency.
The chemical compound used to study the functioning of the WNT signaling pathway was a selective inhibitor of AP1-associated protein kinase 2 (AAK1), developed by researchers at SGC-Unicamp.
Recent studies indicated that AAK1 is involved in endocytosis and that this process – by which cells take into them different types of particles from the extracellular environment, such as micronutrients and even some types of viruses and bacteria – would have a regulatory role in the WNT signaling pathway. . Inhibiting AAK1 would decrease the frequency of endocytosis, these studies indicated.
In order to prove these hypotheses and verify the specific role played by AAK1 in WNT signaling, the researchers used its inhibitor as a chemical probe – a small molecule capable of selectively binding and inhibiting the function of a disease-related protein in a biological model.
The results of the analysis of the experiments showed that AAK1 inhibits beta-catenin-dependent WNT signaling in cells derived from different tissue types by promoting the endocytosis of low-density lipoprotein receptor-related protein 6 (LRP6).
To activate a cascade of signals, the WNT protein initially binds to LRP6. When activated by WNT, LRP6 triggers a series of internal signaling in the cell so that it can carry out processes related to cell development, growth and proliferation. At the same time, WNT activates AAK1 to turn it off and prevent it from proliferating indefinitely and causing problems in the signaling pathway, which can give rise to cancer and a series of other diseases.
To turn off WNT, AAK1 activates the endocytosis of LRP6, in order to reduce its presence on the cell's plasma membrane and make it no longer available to bind to WNT, the researchers found. “In this way, AAK1 is able to turn off the pathway and interrupt the entire signaling cascade,” explained Souza.
The researchers also found that genetic silencing or pharmacological inhibition of AAK1 through the inhibitor they developed, conversely, activates WNT signaling by stabilizing levels of the beta-catenin protein in cells.
“These findings open up the possibility of regulating the activity of this signaling pathway. The chemical compound that inhibits AAK1 can make the pathway more active, for example, by allowing LRP6 to remain in the cell's plasma membrane,” said the researcher.
drug precursor
The discoveries made during the study also confirmed that the AAK1 inhibitor molecule they developed meets the criteria of a chemical probe and that it can be a precursor to a drug that interferes with processes that depend on endocytosis, such as the entry of certain viruses into the host cell. , for example.
Through collaboration with other groups, researchers can study the application of the inhibitor to prevent infection by arboviruses – viruses transmitted by mosquitoes, such as dengue fever, yellow fever and Zika.
“We know that these viruses can infect cells through the endocytosis pathway. By inhibiting this pathway using the chemical probe we developed, it would be possible to block the entry of these viruses into cells,” said Souza.
Following the SGC's premise of operating in an “open science” system, the AAK1 inhibitor will be placed in the public domain, so that any researcher linked to a university, research institution or pharmaceutical industry can carry out studies that eventually result in the development of drugs from the molecule.
“The SGC acts at the beginning of the drug discovery chain. We produce chemical probes for human proteins that can be used as initial molecules for drug development by pharmaceutical industries,” said Souza.
In addition to her, seven other researchers who authored the article are linked to CQMED and SGC-Unicamp.
The article WNT activates the AAK1 kinase to promote clathrin-mediated endocytosis of LRP6 and establish a negative feedback loop(DOI: 10.1016/j.celrep.2018.12.023, by Megan J. Agajanian, Matthew P. Walker, Alison D. Axtman, Roberta R. Ruela-de-Sousa, D. Stephen Serafin, Alex D. Rabinowitz, David M .Graham, Meagan B. Ryan, Tigist Tamir, Yuko Nakamichi, Melissa V. Gammons, James M. Bennett, Rafael M. Couñago, David H. Drewry, Jonathan M. Elkins, Carina Gileadi, Opher Gileadi, Paulo H. Godoi and Michael B. Major, can be read in the magazine Cell reports em www.sciencedirect.com/science/article/pii/S2211124718319533?via%3Dihub.
Article published in Fapesp Agency
