{
  "abstract": "Background and Aims IPF is a progressive, incurable scarring disease of the lung. A common genetic variant near AKAP13 has been associated with IPF susceptibility and elevated gene and protein expression. How this common variant contributes to the pathogenesis of IPF is not known. AKAP13 is a multifunctional scaffold protein, with high expression in lung epithelial cells and integrates intracellular signalling through its interactions with RhoA and protein kinase A (PKA). A13 is a selective small-molecule inhibitor of AKAP13’s RhoGEF domain. This study investigates how an AKAP13 variant alters epithelial signalling and evaluates the therapeutic potential of targeting AKAP13 using A13.Methods CRISPR-Cas9 editing was used to introduce the AKAP13 variant into immortalized human bronchial epithelial cells (iHBECs). Overexpression constructs modelled a truncated AKAP13 isoform lacking the PKA-binding domain. Real-time adhesion and proliferation were measured (xCELLigence). Cell transcriptional profiling is performed using ncounter. Intracellular cAMP was measured by FRET. RhoA activity was measured by G-LISA, and SMAD2 phosphorylation was measured by immunoblotting, both in the presence or absence of LPA stimulation. IPF patient-derived precision-cut lung slices (PCLS) were treated with A13 and analysed for profibrotic gene expression by real-time PCR analysis and SMAD2 nuclear translocation using immunofluorescence and cellpose single cell segmentation.Results iHBECs carrying the AKAP13 variant showed increased expression of truncated isoform of AKAP13. These cells exhibited a ~50% increase in cell adhesion and ~30% reduction in proliferation compared to cells not expressing the AKAP13 variant. These cells showed a profibrotic gene signature had increased RhoA activation and SMAD2 phosphorylation following LPA stimulation. Furthermore, cells harbouring the AKAP13 variant displayed a reduced capacity to generate intracellular cAMP. A13 treatment reversed the pro-adhesive phenotype and significantly reduced RhoA activation. In IPF-derived PCLS (n=4), A13 suppressed SERPINE1, CCN2, and MMP7 expression and reduced SMAD2 nuclear translocation.Conclusions Presence of an AKAP13 variant disrupts epithelial homeostasis and promotes pro-fibrotic signalling. Inhibition of AKAP13’s RhoGEF domain with A13 restores epithelial function and attenuates fibrotic activation, supporting AKAP13 as a therapeutic target in IPF.",
  "authors": [
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "B Liu"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "S Gangi"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "C Wong"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "J May"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "S Wang"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "E Pyman"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "A Vairon"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "M Zarcone"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "EL Lopez Jimenez"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "AE John"
    },
    {
      "affiliations": [
        "Imperial College London, London, UK"
      ],
      "name": "RG Jenkins"
    }
  ],
  "title": "S87 Targeting AKAP13 RhoGEF activity ameliorates pro-fibrotic phenotypes driven by the IPF associated AKAP13 risk variant",
  "uid": "6ed0ecf7-52c2-5fbf-8dcd-33b0ac99e121"
}