title: Bone Morphogenic Protein Type 2 Receptor Mutation-Independent Mechanisms of Disrupted Bone Morphogenetic Protein Signaling in Idiopathic Pulmonary Arterial Hypertension.
abstract: Altered bone morphogenic protein (BMP) signaling, independent of BMPR2 mutations, can result in idiopathic pulmonary arterial hypertension (IPAH). Glucose dysregulation can regulate multiple processes in IPAH. However, the role of glucose in BMP antagonist expression in IPAH has not been characterized. We hypothesized that glucose uptake regulates BMP signaling through stimulation of BMP antagonist expression in IPAH. Using human plasma, lung tissue, and primary pulmonary arterial smooth muscle cells (PASMCs), we examined the protein expression of BMP2, BMP-regulated Smads, and Smurf-1 in patients with IPAH and control subjects. Gremlin-1 levels were elevated in patients with IPAH compared with control subjects, whereas expression of BMP2 was not different. We demonstrate increased Smad polyubiquitination in IPAH lung tissue and PASMCs that was further enhanced with proteasomal inhibition. Examination of the Smad ubiquitin-ligase, Smurf-1, showed increased protein expression in IPAH lung tissue and localization in the smooth muscle of the pulmonary artery. Glucose dose dependently increased Smurf-1 protein expression in control PASMCs, whereas Smurf-1 in IPAH PASMCs was increased and sustained. Conversely, phospho-Smad1/5/8 levels were reduced in IPAH compared with control PASMCs at physiological glucose concentrations. Interestingly, high glucose concentrations decreased phosphorylation of Smad1/5/8 in control PASMCs. Blocking glucose uptake had opposing effects in IPAH PASMCs, and inhibition of Smurf-1 activity resulted in partial rescue of Smad1/5/8 activation and cell migration rates. Collectively, these data suggest that BMP signaling can be regulated through BMPR2 mutation-independent mechanisms. Gremlin-1 (synonym: induced-in-high-glucose-2 protein) and Smurf-1 may function to inhibit BMP signaling as a consequence of the glucose dysregulation described in IPAH.
authors.affiliation: Departments of 1 Pathobiology and.
authors.forename: Jarrod W
authors.initials: JW
authors.lastname: Barnes
authors.affiliation: Departments of 1 Pathobiology and.
authors.forename: Elif T
authors.initials: ET
authors.lastname: Kucera
authors.affiliation: Departments of 1 Pathobiology and.
authors.forename: Liping
authors.initials: L
authors.lastname: Tian
authors.affiliation: Departments of 1 Pathobiology and.
authors.forename: Noël E
authors.initials: NE
authors.lastname: Mellor
authors.affiliation: 2 Immunology, and.
authors.forename: Nina
authors.initials: N
authors.lastname: Dvorina
authors.affiliation: 2 Immunology, and.
authors.forename: William W
authors.initials: WW
authors.lastname: Baldwin
authors.affiliation: 3 Genomic Medicine Institute, Cleveland Clinic, Cleveland, Ohio; and.
authors.forename: Micheala A
authors.initials: MA
authors.lastname: Aldred
authors.affiliation: 4 Pathology, and.
authors.forename: Carol F
authors.initials: CF
authors.lastname: Farver
authors.affiliation: Departments of 1 Pathobiology and.
authors.forename: Suzy A A
authors.initials: SA
authors.lastname: Comhair
authors.affiliation: Departments of 1 Pathobiology and.|5 Department of Medical Biology, Faculty of Medicine, Erciyes University, Kayseri, Turkey.
authors.forename: Metin
authors.initials: M
authors.lastname: Aytekin
authors.affiliation: Departments of 1 Pathobiology and.|6 Pulmonary and Critical Care Medicine, Respiratory Institute.
authors.forename: Raed A
authors.identifier: http://orcid.org/0000-0002-4425-1288
authors.initials: RA
authors.lastname: Dweik
keywords: Gremlin-1; Smurf-1; bone morphogenetic proteins; idiopathic pulmonary arterial hypertension