Cai Y, Bolte C, Le T, Goda C, Xu Y, Kalin TV, Kalinichenko VV. FOXF1 maintains endothelial barrier function and prevents edema after lung injury. Sci Signal. 2016 Apr 19;9(424):ra40.
The regulation of endothelial barrier function involve multiple signaling pathways, structural proteins, and transcription factors. The forkhead protein FOXF1 is a key transcriptional regulator of embryonic lung development, and we used a conditional knockout approach to examine the role of FOXF1 in adult lung homeostasis, injury, and repair. Tamoxifen-regulated deletion of both Foxf1 alleles in endothelial cells of adult mice (Pdgfb-iCreER/Foxf1(-/-)) caused lung inflammation and edema, leading to respiratory insufficiency and death. Deletion of a single Foxf1 allele made heterozygous Pdgfb-iCreER/Foxf1(+/-)mice more susceptible to acute lung injury. FOXF1 abundance decreased in pulmonary endothelial cells of human patients with acute lung injury. Gene expression analysis of pulmonary endothelial cells with homozygous FOXF1 deletion indicated reduced expression of genes critical for maintenance and regulation of adherens junctions. FOXF1 knockdown in vitro and in vivo disrupted adherens junctions, enhanced lung endothelial permeability, and increased the abundance of the mRNA and protein for sphingosine 1-phosphate receptor 1 (S1PR1), a key regulator of endothelial barrier function. Chromatin immunoprecipitation and luciferase reporter assays demonstrated that FOXF1 directly bound to and induced the transcriptional activity of the S1pr1 promoter. Pharmacological administration of S1P to injured Pdgfb-iCreER/Foxf1(+/-)mice restored endothelial barrier function, decreased lung edema, and improved survival. Thus, FOXF1 promotes normal lung homeostasis and repair, in part, by enhancing endothelial barrier function through activation of the S1P/S1PR1 signaling pathway.
Zhang G, Bacelis J, Lengyel C, Teramo K, Hallman M, Helgeland O, Johansson S, Myhre R, Sengpiel V, Njolstad PR, Jacobsson B, Muglia L. Assessing the Causal Relationship of Maternal Height on Birth Size and Gestational Age at Birth: A Mendelian Randomization Analysis. PLoS Med. 2015 Aug 18;12(8):e1001865.
Observational epidemiological studies indicate that maternal height is often associated with gestational age at birth and fetal growth measures (i.e., shorter mothers deliver infants at earlier gestational ages with lower birth weight and birth length). To explain these associations, postulating of different mechanisms has occurred. This study aimed to investigate the casual relationships behind the strong association of maternal height with fetal growth measures (i.e., birth length and birth weight) and gestational age by a Mendelian randomization approach. Our results demonstrate that the observed association between maternal height and fetal growth measures (i.e., birth length and birth weight) is mainly defined by fetal genetics. In contrast, the association between maternal height and gestational age is more likely to be causal. In addition, our approach that utilizes the genetic score derived from the nontransmitted maternal haplotype as a genetic instrument is a novel extension to the Mendelian randomization methodology in casual inference between parental phenotype (or exposure) and outcomes in offspring.