Thyroid hormone (TH) is critical for the maintenance of cellular homeostasis during stress responses, but its role in lung fibrosis is unknown. Here, we found that the activity and expression of iodothyronine deiodinase 2 (DIO2), an enzyme that activates TH, was higher in lungs of patients with idiopathic pulmonary fibrosis compared to control individuals and correlated with disease severity. We also found that Dio2 knockout mice exhibited enhanced bleomycin-induced lung fibrosis. Aerosolized TH delivery increased survival and resolved fibrosis in two models of pulmonary fibrosis in mice (intratracheal bleomycin and inducible TGF-β1). Sobetirome, a TH mimetic, also blunted bleomycin-induced lung fibrosis. Given after bleomycin-induced injury, TH promoted mitochondrial biogenesis, improved mitochondrial bioenergetics and attenuated mitochondria-regulated apoptosis in alveolar epithelial cells both in vivo and in vitro. TH did not blunt fibrosis in Ppargc1a or Pink1 knockout mice suggesting dependence on these pathways. We conclude that the TH anti-fibrotic properties are associated with protection of alveolar epithelial cells and restoration of mitochondrial function and thus may represent an effective therapy for pulmonary fibrosis.

A large-scale effort, termed the Secreted Protein Discovery Initiative (SPDI), was undertaken to identify novel secreted and transmembrane proteins. In the first of several approaches, a biological signal sequence trap in yeast cells was utilized to identify cDNA clones encoding putative secreted proteins. A second strategy utilized various algorithms that recognize features such as the hydrophobic properties of signal sequences to identify putative proteins encoded by expressed sequence tags (ESTs) from human cDNA libraries. A third approach surveyed ESTs for protein sequence similarity to a set of known receptors and their ligands with the BLAST algorithm. Finally, both signal-sequence prediction algorithms and BLAST were used to identify single exons of potential genes from within human genomic sequence. The isolation of full-length cDNA clones for each of these candidate genes resulted in the identification of >1000 novel proteins. A total of 256 of these cDNAs are still novel, including variants and novel genes, per the most recent GenBank release version. The success of this large-scale effort was assessed by a bioinformatics analysis of the proteins through predictions of protein domains, subcellular localizations, and possible functional roles. The SPDI collection should facilitate efforts to better understand intercellular communication, may lead to new understandings of human diseases, and provides potential opportunities for the development of therapeutics.

Glutathione peroxidase 3 is a selenium-dependent enzyme playing a critical role in detoxifying reactive oxidative species and maintaining the genetic integrity of mammalian cells. In this report, we found that the expression of glutathione peroxidase 3 (GPx3) was widely inactivated in prostate cancers. Complete inactivation of GPx3 correlates with a poor clinical outcome. Deletions (hemizygous and homozygous) of GPx3 gene are frequent in prostate cancer samples, occurring in 39% of the samples studied. The rate of methylation of the GPx3 exon 1 region in prostate cancer samples reaches 90%. Overexpression of GPx3 in prostate cancer cell lines induced the suppression of colony formation and anchorage-independent growth of PC3, LNCaP, and Du145 cells. PC3 cells overexpressing GPx3 reduced invasiveness in Matrigel transmigration analysis by an average of 2.7-fold. Xenografted PC3 cells expressing GPx3 showed reduction in tumor volume by 4.8-fold, elimination of metastasis (0/16 versus 7/16), and reduction of animal death (3/16 versus 16/16). The tumor suppressor activity of GPx3 seems to relate to its ability to suppress the expression of c-met. The present findings suggest that GPx3 is a novel tumor suppressor gene.

Over the last decade, great enthusiasm has evolved for microRNA (miRNA) therapeutics. Part of the excitement stems from the fact that a miRNA often regulates numerous related mRNAs. As such, modulation of a single miRNA allows for parallel regulation of multiple genes involved in a particular disease. While many studies have shown therapeutic efficacy using miRNA inhibitors, efforts to restore or increase the function of a miRNA have been lagging behind. The miR-29 family has gained a lot of attention for its clear function in tissue fibrosis. This fibroblast-enriched miRNA family is downregulated in fibrotic diseases which induces a coordinate increase of many extracellular matrix genes. Here, we show that intravenous injection of synthetic RNA duplexes can increase miR-29 levels in vivo for several days. Moreover, therapeutic delivery of these miR-29 mimics during bleomycin-induced pulmonary fibrosis restores endogenous miR-29 function whereby decreasing collagen expression and blocking and reversing pulmonary fibrosis. Our data support the feasibility of using miRNA mimics to therapeutically increase miRNAs and indicate miR-29 to be a potent therapeutic miRNA for treating pulmonary fibrosis.

In this study, we explored the regulation and the role of up-regulated microRNAs in idiopathic pulmonary fibrosis (IPF), a progressive interstitial lung disease of unknown origin. We analyzed the expression of microRNAs in IPF lungs and identified 43 significantly upregulated microRNAs. Twenty-four of the 43 increased microRNAs were localized to the chromosome 14q32 microRNA cluster. We validated the increased expression of miR-154, miR-134, miR-299-5p, miR-410, miR-382, miR-409-3p, miR-487b, miR-31, and miR-127 by quantitative RT-PCR and determined that they were similarly expressed in embryonic lungs. We did not find evidence for differential methylation in this region, but analysis of transcription factor binding sites identified multiple SMAD3-binding elements in the 14q32 microRNA cluster. TGF-b1 stimulation of normal human lung fibroblasts (NHLF) caused up-regulation of microRNAs on chr14q32 that were also increased in IPF lungs. Chromatin immunoprecipitation confirmed binding of SMAD3 to the putative promoter of miR-154. Mir-154 was increased in IPF fibroblasts, and transfection of NHLF with miR-154 caused significant increases in cell proliferation and migration. The increase in proliferation induced by TGF-b was not observed when NHLF or IPF fibroblasts were transfected with a mir-154 inhibitor. Transfection with miR-154 caused activation of the WNT pathway in NHLF. ICG-001 and XAV939, inhibitors of the WNT/b-catenin pathway, reduced the proliferative effect of miR-154. The potential role of miR-154, one of multiple chr14q32 micro-RNA cluster members up-regulated in IPF and a regulator of fibroblast migration and proliferation, should be further explored in IPF.