Contento, G. | Search bioRxiv

bioRxiv2026

Targeting AKAP13 RhoGEF activity ameliorates pro-fibrotic phenotypes driven by the IPF associated AKAP13 risk variant

RationaleIdiopathic pulmonary fibrosis (IPF) is a progressive, incurable scarring disease of the lung. A common genetic variant near AKAP13, a multifunctional scaffold protein that integrates intracellular signalling through its interactions with RhoA and protein kinase A (PKA), has been associated with IPF susceptibility and elevated AKAP13 mRNA expression in lung tissue from patients. However, its contribution to the pathogenesis of IPF remains unclear. ObjectiveThis study investigates how an AKAP13 variant alters epithelial signalling and evaluates the therapeutic potential of targeting AKAP13. Findingsrs62025270-bearing iHBECs exhibited selective upregulation of AKAP13 isoforms, accompanied by increased cell adhesion and reduced proliferation. Transcriptomic profiling revealed upregulated fibrosis-related genes in rs62025270-bearing iHBECs, including SAA1, FGF2, MMP1, CTSB, COL4A1, and CDKN1A. rs62025270-bearing iHBECs also displayed increased RhoA activation and SMAD2 phosphorylation following LPA stimulation. Furthermore, cells harbouring the AKAP13 variant showed reduced intracellular cAMP levels. Pharmacological inhibition of AKAP13 with A13 reversed the pro-adhesive phenotype and reduced RhoA activation in iHBECs. Moreover, in IPF-derived PCLS, A13 suppressed SERPINE1, CCN2, and MMP7 expression, reduced SMAD2 nuclear translocation, and decreased hydroxyproline levels. ConclusionsPresence of an AKAP13 variant disrupts epithelial homeostasis and promotes pro-fibrotic signalling. Inhibition of AKAP13s RhoGEF domain with A13 restores epithelial function and attenuates fibrotic activation, supporting AKAP13 as a therapeutic target in IPF.

genetics↗

bioRxiv2024

Pyruvate metabolism dictates fibroblast sensitivity to GLS1 inhibition during fibrogenesis

Fibrosis is a chronic disease characterized by excessive extracellular matrix (ECM) production which leads to destruction of normal tissue architecture and disruption of organ function. Fibroblasts are key effector cells of this process and respond to a host of pro-fibrotic stimuli, including notably the pleiotropic cytokine, TGF-{beta}1, which promotes fibroblast to myofibroblast differentiation. This is accompanied by the simultaneous rewiring of metabolic networks to meet the biosynthetic and bioenergetic needs of contractile and ECM-synthesizing cells, but the exact mechanisms involved remain poorly understood. In this study, we report that extracellular nutrient availability profoundly influences the TGF-{beta}1 transcriptome of primary human lung fibroblasts (pHLFs) and the "biosynthesis of amino acids" emerges as a top enriched transcriptional module influenced by TGF-{beta}1. We subsequently uncover a key role for pyruvate in influencing the pharmacological impact of glutaminase (GLS1) inhibition during TGF-{beta}1-induced fibrogenesis. In pyruvate replete conditions which mimic the physiological concentration of pyruvate in human blood, GLS1 inhibition is ineffective in blocking TGF-{beta}1-induced fibrogenesis, as pyruvate is able to be used as the substrate for glutamate and alanine production via glutamate dehydrogenase (GDH) and glutamic-pyruvic transaminase 2 (GPT2), respectively. We further show that dual targeting of either GPT2 or GDH in combination with GLS1-inhibition is required to fully block TGF-{beta}1-induced collagen synthesis. These findings embolden a therapeutic strategy aimed at additional targeting of mitochondrial pyruvate metabolism in the presence of a glutaminolysis inhibitor in order to interfere with the pathological deposition of collagen in the setting of pulmonary fibrosis and potentially other fibrotic conditions.

cell biology↗