Biology subjects

Bastiaens, P.

Publications and source records attributed to Bastiaens, P..

6 recordsLinked to original sources

bioRxiv2026

Reversible Opto-Chemical activation of KRASG12V signaling with near single-cell precision

KRAS mutations drive some of the most lethal carcinomas, and genomic and inducible systems have established many of the cellular and tissue-level consequences. However, these approaches operate at the level of oncogene expression, allowing for cellular adaptation that masks the individual role of KRAS oncoprotein signaling. Here, we developed a reversible Opto-Chemical system to activate KRAS signaling by chemically translocating a cytosolic mutant KRASG12V G-domain to the plasma membrane upon light or small-molecule input. In MDCK cells, the G-domain plasma membrane recruitment activated downstream signaling and reduced collective migration. In mouse small Intestinal Organoids, G-domain recruitment promoted increased crypt size and number under Epidermal Growth Factor-deprived conditions. We further showed that the increased number of crypts depended on continuous KRASG12V signaling. Finally, under the same deprived conditions, localized activation in just one budding crypt promoted crypt formation compared to controls. This system decouples oncoprotein activity from oncogene expression, allowing to investigate the KRAS signaling contribution to early epithelial transformation.

Systems Biology↗

bioRxiv2018

A synthetic morphogenic perceptory cell

Reconstitution of artificial cells capable of transducing extracellular signals into cytoskeletal changes is a challenge in synthetic biology that will reveal fundamental principles of non-equilibrium phenomena of cellular morphogenesis and information processing. Here, we generated a life-like Synthetic Morphogenic Membrane System (SynMMS) by encapsulating a dynamic microtubule (MT) aster and a light-inducible signaling system driven by GTP/ATP chemical potential into cell-sized vesicles. The biomimetic design of the light-induced signaling system embodies the operational principle of morphogen induced Rho-GTPase signal transduction in cells. Activation of synthetic signaling promotes membrane-deforming growth of MT-filaments by dynamically elevating the membrane-proximal concentration of tubulin. The resulting membrane deformations enable the recursive coupling of the MT-aster with the signaling system, creating global self-organized morphologies that reorganize towards external light cues in dependence on prior sensory experience that is stored in the dynamically maintained morphology. SynMMS thereby signifies a step towards bio-inspired engineering of self-organized cellular morphogenesis.

synthetic biology↗

bioRxiv2018

A spatially regulated GTPase cycle of Rheb controls growth factor signaling to mTORC1

Growth factors initiate anabolism by activating mechanistic target of rapamycin complex 1 (mTORC1) via the small GTPase Rheb. We show that the GTPase cycle of Rheb is spatially regulated by the interaction with its GDI-like solubilizing factor (GSF) - PDE{delta}. Arl2-GTP mediated localized release of cytosolic Rheb-GTP from PDE{delta} deposits it onto perinuclear membranes where it forms a complex with mTORC1. The membrane associated GTPase activating protein (GAP) TSC2 hydrolyzes Rheb-GTP, weakening the interaction with mTOR. Rheb-GDP is readily released into the cytosol where it is maintained soluble by interaction with PDE{delta}. This solubilized Rheb is re-activated by nucleotide exchange to be re-deposited by Arl2-mediated release onto perinuclear membranes. This spatial GTPase cycle thereby enables mTORC1 activation to be solely controlled by growth factor induced inactivation of TSC2. The coupling between mTOR activation and spatially regulated Rheb nucleotide exchange makes growth factor induced proliferation critically dependent on PDE{delta} expression.

cell biology↗

bioRxiv2018

PDEδ inhibition impedes the proliferation and survival of human colorectal cancer cell lines harboring oncogenic KRas

Novelty and ImpactThe undruggable KRas is a prevalent oncogene in CRC with poor prognosis. In hPDAC cells pharmacological targeting of PDE{delta} affects oncogenic KRas signaling, but it remained unclear whether this approach is transferable to other cancer cells. Here, we show that genetic and pharmacologic PDE{delta} inhibition also impedes the proliferation of oncogenic, but not wild-type KRas bearing CRC cells indicating that PDE{delta} inhibition is a specific tool for targeting growth of oncogenic KRas bearing CRC.\n\nAbstractRas proteins, most notably KRas, are prevalent oncogenes in human cancer. Plasma membrane localization and thereby signaling of KRas is regulated by the prenyl-binding protein PDE{delta}. Recently, we have reported the specific anti-proliferative effects of PDE{delta} inhibition in KRas-dependent human pancreatic ductal adenocarcinoma cell lines. Here, we investigated the proliferative dependence on the solubilizing activity of PDE{delta} of human colorectal cancer (CRC) cell lines with or without oncogenic KRas mutations. Our results show that genetic and pharmacologic interference with PDE{delta} specifically inhibits proliferation and survival of CRC cell lines harboring oncogenic KRas mutations whereas isogenic cell lines in which the KRas oncogene has been removed, or cell lines with oncogenic BRaf mutations or EGFR overexpression are not dependent on PDE{delta}. Pharmacological PDE{delta} inhibition is therefore a possible new avenue to target oncogenic KRas bearing CRC.

cell biology↗

bioRxiv2018

A conformational sensor based on genetic code expansion reveals an autocatalytic component in EGFR activation

Epidermal growth factor receptor (EGFR) activation by growth factors (GFs) relies on dimerization and allosteric activation of its intrinsic kinase activity, resulting in trans-phosphorylation of tyrosines on its C-terminal tail. While structural and biochemical studies identified this EGF-induced allosteric activation, imaging collective EGFR activation in cells and molecular dynamics simulations pointed at additional catalytic EGFR activation mechanisms. To gain more insight in EGFR activation mechanisms in living cells, we developed a Forster Resonance Energy Transfer (FRET) based conformational EGFR indicator (CONEGI) using genetic code expansion that reports on conformational transitions in the EGFR activation loop. Comparing conformational transitions, self-association and auto-phosphorylation of CONEGI and its Y845F mutant revealed that Y845 phosphorylation induces a catalytically active conformation in EGFR monomers. This conformational transition depends on EGFR kinase activity and auto-phosphorylation on its C-terminal tail, generating a looped causality that leads to autocatalytic amplification of EGFR phosphorylation at low EGF dose.

molecular biology↗

bioRxiv2017

Contact inhibitory Eph signalling decouples EGFR activity from vesicular recycling to generate contextual plasticity

The ability of cells to adapt their behavior to growth factors in relation to their environment is an essential aspect of tissue development and homeostasis. Here we show that Eph receptor signaling from cell-cell contacts changes the cellular response to EGFR activation by altering its vesicular trafficking. Eph receptor activation traps EGFR in Rab5-positive early endosomes through an inhibition of Akt-dependent vesicular recycling. By altering the spatial distribution of EGFR activity during EGF stimulation, Eph receptor activation selectively suppresses migratory Akt signaling from the plasma membrane, while preserving proliferative ERK signaling from endosomes. We also show that soluble extracellular signals engaging the G-protein coupled receptor Kiss1 similarly suppress vesicular recycling to alter EGFR signaling. The cellular environment can thus modulate EGFR vesicular trafficking dynamics to generate context-dependent responses to EGF stimulation.\n\nSummaryEph receptor activation generates context-dependent cellular responses to EGFR activation by altering its vesicular trafficking dynamics.

cell biology↗