ATP13A3Variants Promote Pulmonary Arterial Hypertension by Disrupting Polyamine Transport

Abstract

AimsPotential loss-of-function variants ofATP13A3, the gene encoding a P5B-type transport ATPase of undefined function, were recently identified in pulmonary arterial hypertension (PAH) patients. ATP13A3 is implicated in polyamine transport but its function has not been fully elucidated. Here, we sought to determine the biological function of ATP13A3 in vascular endothelial cells and how PAH-associated mutations may contribute to disease pathogenesis. We also generated mice harbouring anAtp13a3variant analogous to a human disease-associated variant to establish whether these mice develop PAH.Methods and ResultsWe studied the impact of ATP13A3 deficiency and overexpression in endothelial cell (EC) models (human pulmonary ECs, blood outgrowth ECs (BOECs) and HMEC-1 cells), including a PAH patient-derived BOEC line harbouring an ATP13A3 variant (LK726X). ATP13A3 localised to the recycling endosomes of human ECs. Knockdown of ATP13A3 in ECs generally reduced the basal polyamine content, consistently reduced putrescine uptake, and altered the expression of enzymes involved in polyamine metabolism. Conversely, overexpression of wild-type ATP13A3 increased polyamine uptake, with an overall preference of putrescine > spermidine > spermine. Functionally, loss of ATP13A3 was associated with reduced EC proliferation, increased apoptosis in serum starvation and increased monolayer permeability to thrombin. Assessment of five PAH-associated missense ATP13A3 variants (L675V, M850I, V855M, R858H, L956P) confirmed loss-of-function phenotypes represented by impaired polyamine transport and dysregulated EC function. Furthermore, mice carrying a heterozygous germ-lineAtp13a3frameshift variant representing a human mutation spontaneously developed a PAH phenotype, with increased pulmonary pressures, right ventricular remodelling and muscularisation of pulmonary vessels.ConclusionWe identify ATP13A3 as a polyamine transporter, deficiency of which leads to EC dysfunction and predisposes to PAH. This suggests a need for targeted therapies to alleviate the imbalances in polyamine homeostasis and EC dysfunction in PAH.Translational perspectiveRare missenseATP13A3disease-associated variants have been identified in patients with pulmonary arterial hypertension (PAH), though their pathogenicity has not been confirmed as the function of ATP13A3 is not known. We have identified ATP13A3 as a polyamine transporter, showing that ATP13A3 deficiency impaired polyamine homeostasis and uptake, and drove endothelial dysfunction. Conversely, overexpression increased polyamine uptake and rescued the proapoptotic phenotype of cells harbouring a disease-associate variant. Mice heterozygous for a disease-associated Atp13a3 mutation spontaneously develop PAH. These findings support the rationale for exploring dysregulated polyamine homeostasis in PAH and suggest a potential for therapeutic targeting of polyamine pathways in PAH.

Overexpression of miR-3168 impairs angiogenesis in Pulmonary Arterial Hypertension: Insights from circulating miRNA analysis

“…Recently, miR-31-5p was reported to be upregulated in the right ventricle of PAH patients, especially in male patients, where its expression was regulated by a network of circular RNAs and lncRNAs [45]. Besides, miR-31-5p could target ATP13A3 , whose haploinsufficiency causes PAH [46,47]. Thus, the implication of this miRNA in PAH pathogenesis make sense if we focus in proliferation/inhibition and how it is reported to interact with vascular smooth muscle cells [41,43], it could help in the overall proliferative environment of PAH-development with enhanced SMC/PAEC/AF proliferation and migration.…”

What Is All of the Hype About? Hypusine Signaling as a Driver of Pulmonary Hypertension

“…The central role of eIF5A in both metabolic and molecular alterations is raising the possibility that Hyp eIF5A serves as a coordinator of metabolic and molecular changes in PAH PASMCs. Furthermore, Hyp eIF5A regulates inflammation and immunity ( 3 ), the deficiency of polyamine transporter ATP13A3 was recently linked to the PA endothelial dysfunction in PAH ( 13 ) ( Figure 1 ), and Lemay and colleagues observed that inhibition of hypusine signaling decreases TGFβ-dependent production of matrix proteins by right ventricular fibroblasts ( 5 ), suggestive of broad multicellular and multiorgan involvement of eIF5A/polyamine metabolism in PAH pathogenesis.…”