PI3K/AKT pathway

PI3K/AKT pathway
Name	PI3K/AKT pathway
Caption	Schematic of PI3K/AKT signaling
Organism	Eukaryota

PI3K/AKT pathway The PI3K/AKT pathway is a conserved intracellular signaling cascade that transduces extracellular stimuli into cellular responses. Originating from receptor activation, the cascade regulates metabolism, growth, survival, and motility and is implicated in development and disease. Key discoveries were advanced by researchers at institutions such as Harvard University, Massachusetts Institute of Technology, Johns Hopkins University, and Cold Spring Harbor Laboratory and have been discussed in journals like Nature, Science, and Cell.

Overview

The pathway is initiated when receptor tyrosine kinases or G protein–coupled receptors engage ligands studied by teams at Stanford University, University of Cambridge, University of Oxford, and University of California, San Francisco. Seminal work by laboratories associated with Cold Spring Harbor Laboratory and The Scripps Research Institute mapped core components, while clinical links were pursued at Mayo Clinic, Memorial Sloan Kettering Cancer Center, and Dana-Farber Cancer Institute. Structural insights came from collaborations involving European Molecular Biology Laboratory, Max Planck Society, and Riken.

Components and Molecular Mechanism

Core enzymatic players include class I phosphoinositide 3-kinases (PI3Ks) discovered in biochemical studies at University of California, Berkeley and the serine/threonine kinase AKT (also known as protein kinase B) characterized in work from University of Pennsylvania and Yale University. Adaptor proteins and lipid second messengers connect membrane receptors such as the epidermal growth factor receptor studied at Memorial Sloan Kettering Cancer Center and the insulin receptor characterized at University of Cambridge to downstream effectors like mTOR, which was elucidated by researchers affiliated with MIT and University of Toronto. The conversion of PIP2 to PIP3 by PI3K recruits pleckstrin homology domain–containing proteins including AKT and PDK1; PDK1 phosphorylation and mTOR complex 2–mediated phosphorylation fully activate AKT, a mechanism detailed in publications from Harvard Medical School and Imperial College London. Negative regulation involves the lipid phosphatase PTEN, first cloned by groups at St. Jude Children's Research Hospital and University of California, Los Angeles, and protein phosphatases such as PP2A investigated at ETH Zurich.

Regulation and Crosstalk

The pathway is modulated by feedback loops and cross-communication with signaling axes uncovered by consortia including The Cancer Genome Atlas and ENCODE. Crosstalk partners include the RAS–RAF–MEK–ERK cascade studied at Cold Spring Harbor Laboratory and Francis Crick Institute, the WNT pathway investigated at Johns Hopkins University, and the TGF-β signaling network analyzed by researchers at University of California, San Diego. Metabolic regulators characterized at University of Basel and inflammatory signals examined at Karolinska Institutet further shape output. Oncogenic mutations in receptors or RAS family members identified in cohorts from MD Anderson Cancer Center and Memorial Sloan Kettering Cancer Center alter pathway dynamics, while tumor suppressor loss at loci mapped by Broad Institute modifies feedback control.

Physiological Roles

In development, PI3K/AKT signaling guides processes studied in model systems pioneered at The Scripps Research Institute and Wistar Institute, including cell proliferation and differentiation examined by groups at Stanford University and University of Cambridge. In metabolism, insulin-mediated AKT activation was characterized in clinical and basic studies at University of Oxford and Joslin Diabetes Center, linking to glucose homeostasis and lipid synthesis investigated by teams at University of Copenhagen and University of Melbourne. Neuronal survival and plasticity roles were defined in laboratories at Salk Institute, Massachusetts Institute of Technology, and Max Planck Society, while cardiovascular research at Cleveland Clinic and University College London connected pathway activity to endothelial function and cardiomyocyte hypertrophy.

Pathological Implications and Therapeutic Targeting

Aberrant activation is implicated in cancer types profiled by The Cancer Genome Atlas and treated at Memorial Sloan Kettering Cancer Center and MD Anderson Cancer Center, where PI3K inhibitors developed by pharmaceutical companies and academic collaborations underwent trials at centers including National Institutes of Health and European Medicines Agency studies. PTEN loss and AKT mutations identified in cohorts from Broad Institute and Wellcome Sanger Institute associate with tumor progression and therapy resistance documented in clinical series at Dana-Farber Cancer Institute. Beyond oncology, dysregulation contributes to insulin resistance and type 2 diabetes studied at Joslin Diabetes Center and University of California, San Francisco, as well as neurodegenerative disorders researched at Alzheimer's Disease Research Center programs. Therapeutic approaches include small-molecule inhibitors, allosteric modulators, and combination regimens evaluated in trials coordinated by National Cancer Institute and industry partners like GlaxoSmithKline, Novartis, and Pfizer.

Experimental Methods and Models

Key experimental systems include genetically engineered mouse models developed at The Jackson Laboratory and conditional alleles generated using CRISPR methods refined at Broad Institute and Harvard University. Cell-based assays use lines originally derived and distributed by repositories such as American Type Culture Collection and transfection tools standardized by Addgene. Biochemical analyses rely on mass spectrometry platforms advanced at Pacific Northwest National Laboratory and cryo-electron microscopy infrastructure supported by European Molecular Biology Laboratory. Clinical and translational studies leverage datasets from The Cancer Genome Atlas and biobanks curated at UK Biobank and ClinicalTrials.gov registries.

Category:Signal transduction