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Biology subjects

Linding, R.

Publications and source records attributed to Linding, R..

4 recordsLinked to original sources

Thermodynamically Explicit Kinetics with Potential for Genome-wide Application

Metabolic processes are inherently dynamic, yet genome-scale models are often limited to steady-state analysis, which cannot capture time-dependent responses crucial for understanding complex diseases like cancer. This work introduces a Thermodynamically Explicit (TDE) kinetic framework to bridge this gap by constructing dynamic metabolic models grounded in fundamental thermodynamic principles. Our approach uses standard chemical potentials to derive simplified rate laws for metabolic reactions, reducing the kinetic complexity of each reaction to a single, biochemically determined prefactor ({lambda}), which we will name kinetic capacity factor. The number of parameters in the suggested TDE kinetics is indeed minimal in the sense that it uses the lowest possible number of free parameters required to define a reaction rate that is both dynamic and thermodynamically consistent. We demonstrate the validity and practical application of this framework by re-parameterizing a well-established kinetic model of glycolysis. The resulting TDE model successfully reproduces the dynamic behavior of the original, more complex model in simulations. By streamlining the parameterization process, the TDE kinetic framework offers a powerful and scalable tool for building genome-wide dynamic metabolic models. This approach paves the way for more accurate and predictive simulations of metabolic behavior, with significant potential for applications in systems biology, medicine, and biotechnology.

biophysics↗

High-dose oncogenic PIK3CA drives constitutive cellular stemness through self-sustained TGFβ pathway activation

Activating PIK3CA mutations are known "drivers" of human cancer and developmental overgrowth syndromes. We recently demonstrated that the "hotspot" PIK3CAH1047R variant exerts unexpected allele dose-dependent effects on stemness in human pluripotent stem cells (hPSCs). In the present study, we combine high-depth transcriptomics, total proteomics and reverse-phase protein arrays to reveal potentially disease-related alterations in heterozygous cells, and to assess the contribution of activated TGF{beta} signalling to the stemness phenotype of PIK3CAH1047R homozygous cells. We demonstrate signalling rewiring as a function of oncogenic PI3K signalling dose, and provide experimental evidence that self-sustained stemness is causally related to enhanced autocrine NODAL/TGF{beta} signalling. A significant transcriptomic signature of TGF{beta} pathway activation in PIK3CAH1047R heterozygous was observed but was modest and was not associated with the stemness phenotype seen in homozygous mutants. Notably, the stemness gene expression in PIK3CAH1047R homozygous iPSCs was reversed by pharmacological inhibition of TGF{beta} signalling, but not by pharmacological PI3K pathway inhibition. Altogether, this provides the first in-depth analysis of PI3K signalling in human pluripotent stem cells and directly links dose-dependent PI3K activation to developmental NODAL/TGF{beta} signalling.

cancer biology↗

Probability-based detection of phosphoproteomic uncertainty reveals rare signaling events driven by oncogenic kinase gene fusion

We describe a novel Bayesian method for estimating protein concentration and phosphorylation site occupancy ratios from mass spectrometry experiments. Our variance model assigns standard deviations to all quantitative ratios, even when only a single peptide is observed, increasing the number of quantifiable observations in a sample compared to conventional methods. We further demonstrate the application of this method using a dataset investigating the impact of the PRKAR1A-RET gene fusion in immortalized thyroid cells.

systems biology↗

Comprehensive substrate specificity profiling of the human nek kinome reveals unexpected signaling outputs

Human NimA-related kinases (Neks) have multiple mitotic and non-mitotic functions, but few substrates are known. We systematically determined the phosphorylation-site motifs for the entire Nek kinase family, except for Nek11. While all Nek kinases strongly select for hydrophobic residues in the -3 position, the family separates into four distinct groups based on specificity for a serine versus threonine phospho-acceptor, and preference for basic or acidic residues in other positions. Unlike Nek1-Nek9, Nek10 is a dual-specificity kinase that efficiently phosphorylates itself and peptide substrates on serine and tyrosine, and its activity is enhanced by tyrosine auto-phosphorylation. Nek10 dual-specificity depends on residues in the HRD+2 and APE-4 positions that are uncommon in either serine/threonine or tyrosine kinases. Finally, we show that the phosphorylation-site motifs for the mitotic kinases Nek6, Nek7 and Nek9 are essentially identical to that of their upstream activator Plk1, suggesting that Nek6/7/9 function as phospho-motif amplifiers of Plk1 signaling.

biochemistry↗