GLUT10 deficiency leads to oxidative stress and non-canonical αvβ3 integrin-mediated TGFβ signalling associated with extracellular matrix disarray in arterial tortuosity syndrome skin fibroblasts

Abstract

Arterial tortuosity syndrome (ATS) is an autosomal recessive connective tissue disorder caused by loss-of-function mutations in SLC2A10, which encodes facilitative glucose transporter 10 (GLUT10). The role of GLUT10 in ATS pathogenesis remains an enigma, and the transported metabolite(s), i.e. glucose and/or dehydroascorbic acid, have not been clearly elucidated. To discern the molecular mechanisms underlying the ATS aetiology, we performed gene expression profiling and biochemical studies on skin fibroblasts. Transcriptome analyses revealed the dysregulation of several genes involved in TGFβ signalling and extracellular matrix (ECM) homeostasis as well as the perturbation of specific pathways that control both the cell energy balance and the oxidative stress response. Biochemical and functional studies showed a marked increase in ROS-induced lipid peroxidation sustained by altered PPARγ function, which contributes to the redox imbalance and the compensatory antioxidant activity of ALDH1A1. ATS fibroblasts also showed activation of a non-canonical TGFβ signalling due to TGFBRI disorganization, the upregulation of TGFBRII and connective tissue growth factor, and the activation of the αvβ3 integrin transduction pathway, which involves p125FAK, p60Src and p38 MAPK. Stable GLUT10 expression in patients' fibroblasts normalized redox homeostasis and PPARγ activity, rescued canonical TGFβ signalling and induced partial ECM re-organization. These data add new insights into the ATS dysregulated biological pathways and definition of the pathomechanisms involved in this disorder.

Glucose transporter type 10—lacking in arterial tortuosity syndrome—facilitates dehydroascorbic acid transport

“…These transfected cells do not only re-express GLUT10 but also rescue a control-like phenotype concerning the extracellular matrix homeostasis and GLUT10-dependent canonical signal transduction mechanisms, as shown in [25]. The absence of the immunoreactivity of GLUT10 was observed in nontransfected ( Fig.…”

“…P1 was intentionally used in the re-expression experiments to avoid any interference with an eventual mutated protein present in the ATS fibroblasts, because of the almost complete lack of GLUT10 mRNA, due to the activation of nonsense-mediated mRNA decay. These transfected cells do not only re-express GLUT10 but also rescue a control-like phenotype concerning the extracellular matrix homeostasis and GLUT10-dependent canonical signal transduction mechanisms, as shown in [25]. The absence of the immunoreactivity of GLUT10 was observed in nontransfected ( Fig.…”

“…Indeed, changes of gene expression has been demonstrated by a recently published transcriptome analyses in ATS fibroblasts. The alterations affected the expression of several genes involved not only in TGFb signaling and extracellular matrix organization and homeostasis but also in specific pathways that control cell energy balance and the oxidative stress response [25]. Although further studies are needed to clarify the role of these changes in the pathogenesis of ATS, the results presented here clearly show that GLUT10 can mediate the membrane transport of DAA and this transport is defective in the endomembranes of ATS fibroblasts.…”

“…A stable GLUT10 expression vector was generated as previously reported [25]. Briefly, the full length of human SLC2A10 cds (refseq: NM_030777.3) was amplified from total RNA of normal skin fibroblasts with the SuperScript III One-Step RT-PCR System and inserted into the eukaryotic pEF6/V5-His-TOPO TM expression vector containing the blasticidin-selectable marker gene and the strong human elongation factor 1a promoter (Life Technologies).…”

SLC2A knockout mice deficient in ascorbic acid synthesis recapitulate aspects of arterial tortuosity syndrome and display mitochondrial respiration defects

“…Arterial histopathology shows disorganization and fragmentation of the elastic fibers [1,[7][8][9][10]. Cultured fibroblasts of ATS patients show disorganization of the actin cytoskeleton and multiple extracellular matrix (ECM) components, including fibronectin, fibrillin, type 3 collagen, type 5 collagen and decorin [11,12].…”