Biology subjects

Clavane, E. M.

Publications and source records attributed to Clavane, E. M..

3 recordsLinked to original sources

bioRxiv2024

Chloride intracellular channel 4 (CLIC4) is a global regulator of type 1 interferon signaling in Systemic Sclerosis (SSc) epithelial cells

ObjectivesSystemic sclerosis (SSc) is an autoimmune disease in which an immune-related injury induces fibrosis of the skin, progressing to affect the internal organs in the most serve cases. Type 1 interferon (IFN) signaling plays a major role in SSc disease progression. We have previously shown the chloride intracellular channel 4 (CLIC4) is upregulated in SSc skin fibroblasts and plays an important role in SSc fibrosis. In this study we investigated the role of CLIC4 in SSc keratinocyte biology. Methodshealthy (HC) and SSc skin biopsies were analysed by immunohistochemistry for the expression of CLIC4. The skin keratinocyte cell line Hacats was stimulated with a range of type 1 IFN signaling agonists (POLY I:C, POLY dA:Dt, ODN 2216 and IFN-). CLIC4 was inhibited with the chloride channel inhibitors NPPB and IAA-94 or siRNA. Conditioned media from HC or SSc fibroblasts was employed for indirect co-culture of Hacats and HUVECs. ResultsSSc skin biopsies showed high levels of CLIC4 in SSc skin fibroblasts, keratinocytes and endothelial cells compared to HC. Co-culture of Hacats and Huvecs with SSc fibroblast media induced CLIC4 expression. CLIC4 played an important role in type 1 IFN signalling in keratinocytes. Inhibition of CLIC4 blocked TLR3, TLR9 and cGAS mediated activation of the type 1 IFN signaling pathway. Additionally, inhibition of CLIC4 prevented SSc fibroblast media from inducing a type 1 IFN response in keratinocytes. ConclusionsThe data presented in this study suggests CLIC4 is a global regulator of type 1 IFN signalling in SSc epithelial cells. Key MessagesO_ST_ABSWhat is already knownC_ST_ABSSSc disease progression is driven in part by a Type 1 IFN signature and CLIC4 has previously been implicated in SSc fibroblast activation. What this study addsWe show for the first time CLIC4 is a regulator of type 1 interferon signalling in epithelial cells and plays an important role in the signalling found in SSc skin. How this study might affect researchTargeting CLIC4 in the context of SSc may disrupt the fibrosis and inflammation associated with SSc.

immunology↗

bioRxiv2024

Small molecule modulation of insulin receptor-insulin like growth factor-1 receptor heterodimers in human endothelial cells

ObjectivesThe insulin receptor (IR) and insulin like growth factor-1 receptor (IGF-1R) are heterodimers consisting of two extracellular -subunits and two transmembrane {beta} -subunits. Insulin {beta} and insulin like growth factor-1 {beta} hemi-receptors can heterodimerize to form hybrids composed of one IR {beta} and one IGF-1R {beta}. The function of hybrids in the endothelium is unclear. We sought insight by developing a small molecule capable of reducing hybrid formation in endothelial cells. MethodsWe performed a high-throughput small molecule screening, based on a homology model of hybrid structure. Endothelial cells were studied using western blotting and qPCR to determine the effects of small molecules that reduced hybrid formation. ResultsOur studies unveil a first-in-class quinoline-containing heterocyclic small molecule that reduces hybrids by >50% in human umbilical vein endothelial cells (HUVECs) with no effects on insulin or insulin like growth factor-1 receptors. This small molecule reduced expression of the negative regulatory p85 subunit of phosphatidylinositol 3-kinase, increased basal phosphorylation of the downstream target Akt and enhanced insulin/insulin-like growth factor-1 and shear stress-induced serine phosphorylation of Akt. In primary saphenous vein endothelial cells (SVEC) from patients with type 2 diabetes mellitus undergoing coronary artery bypass (CABG) surgery, hybrid receptor expression was greater than in patients without type 2 diabetes mellitus. The small molecule significantly reduced hybrid expression in SVEC from patients with type 2 diabetes mellitus. ConclusionsWe identified a small molecule that decreases the formation of IR: IGF-1R hybrid receptors in human endothelial cells, without significant impact on the overall expression of IR or IGF-1R. In HUVECs, reduction of IR: IGF-1R hybrid receptors leads to an increase in insulin-induced serine phosphorylation of the critical downstream signalling kinase, Akt. The underpinning mechanism appears, at least in part to involve the attenuation of the adverse effect of IR: IGF-1R hybrid receptors on PI3-kinase signalling. HighlightsO_LIWe have discovered a small molecule (HI) that inhibits insulin receptor/IGF-1 receptor hybrid formation. C_LIO_LIHI reveals previously unrecognised actions of insulin receptor/IGF-1 receptor hybrids distinct to insulin and IGF-1 receptors in endothelial cells. C_LIO_LITreatment of endothelial cells with HI enhances activity of the downstream signalling kinase Akt due to inhibitory regulation via PI3-K. C_LI

cell biology↗

bioRxiv2022

The Beta secretase BACE1 drives Systemic Sclerosis fibroblasts activation through B-catenin and Notch signalling

The beta-amyloid precursor protein cleaving enzyme 1 (BACE1) is well known for its role in the development of Alzheimers disease. Recent publications, including our own, have demonstrated a role for this enzyme in other chronic diseases. The aim of this study was to investigate the role of BACE1 in the autoimmune disease systemic sclerosis (SSc). BACE1 protein levels were elevated in SSc patient skin. Inhibition of BACE1 with small molecule inhibitors or siRNA blocked SSc and fibrotic stimuli mediated fibroblast activation. Furthermore, we show that BACE1 regulation of dermal fibroblast activation is dependent on {beta}-catenin and Notch signalling. The Neurotropic factor BDNF negatively regulates BACE1 expression and activity in dermal fibroblasts. Finally, sera from SSc patients show higher A{beta} and lower BDNF levels compared to healthy controls. The ability of BACE1 to regulate SSc fibroblast activation reveals a new therapeutic target in SSc. Several BACE1 inhibitors have been shown to be safe in clinical trials for Alzheimers disease and could be repurposed to ameliorate fibrosis progression.

immunology↗