Aberrant Multiciliogenesis in Idiopathic Pulmonary Fibrosis.

We previously identified a novel molecular subtype of idiopathic pulmonary fibrosis (IPF) defined by increased expression of cilium-associated genes, airway mucin gene MUC5B, and KRT5 marker of basal cell airway progenitors. Here we show the association of MUC5B and cilia gene expression in human IPF airway epithelial cells, providing further rationale for examining the role of cilium genes in the pathogenesis of IPF. We demonstrate increased multiciliogenesis and changes in motile cilia structure of multiciliated cells both in IPF and bleomycin lung fibrosis models. Importantly, conditional deletion of a cilium gene, Ift88 (intraflagellar transport 88), in Krt5 basal cells reduces Krt5 pod formation and lung fibrosis, whereas no changes are observed in Ift88 conditional deletion in club cell progenitors. Our findings indicate that aberrant injury-activated primary ciliogenesis and Hedgehog signaling may play a causative role in Krt5 pod formation, which leads to aberrant multiciliogenesis and lung fibrosis. This implies that modulating cilium gene expression in Krt5 cell progenitors is a potential therapeutic target for IPF.

IFN-α suppresses GATA3 transcription from a distal exon and promotes H3K27 trimethylation of the CNS-1 enhancer in human Th2 cells.

CD4(+) Th2 development is regulated by the zinc finger transcription factor GATA3. Once induced by acute priming signals, such as IL-4, GATA3 poises the Th2 cytokine locus for rapid activation and establishes a positive-feedback loop that maintains elevated GATA3 expression. Type I IFN (IFN-α/ß) inhibits Th2 cells by blocking the expression of GATA3 during Th2 development and in fully committed Th2 cells. In this study, we uncovered a unique mechanism by which IFN-α/ß signaling represses the GATA3 gene in human Th2 cells. IFN-α/ß suppressed expression of GATA3 mRNA that was transcribed from an alternative distal upstream exon (1A). This suppression was not mediated through DNA methylation, but rather by histone modifications localized to a conserved noncoding sequence (CNS-1) upstream of exon 1A. IFN-α/ß treatment led to a closed conformation of CNS-1, as assessed by DNase I hypersensitivity, along with enhanced accumulation of H3K27me3 mark at this CNS region, which correlated with increased density of total nucleosomes at this putative enhancer. Consequently, accessibility of CNS-1 to GATA3 DNA binding activity was reduced in response to IFN-α/ß signaling, even in the presence of IL-4. Thus, IFN-α/ß disrupts the GATA3-autoactivation loop and promotes epigenetic silencing of a Th2-specific regulatory region within the GATA3 gene.

Cutting edge: Type I IFN reverses human Th2 commitment and stability by suppressing GATA3.

T helper 2 cells regulate inflammatory responses to helminth infections while also mediating pathological processes of asthma and allergy. IL-4 promotes Th2 development by inducing the expression of the GATA3 transcription factor, and the Th2 phenotype is stabilized by a GATA3-dependent autoregulatory loop. In this study, we found that type I IFN (IFN-alpha/beta) blocked human Th2 development and inhibited cytokine secretion from committed Th2 cells. This negative regulatory pathway was operative in human but not mouse CD4(+) T cells and was selective to type I IFN, as neither IFN-gamma nor IL-12 mediated such inhibition. IFN-alpha/beta blocked Th2 cytokine secretion through the inhibition of GATA3 during Th2 development and in fully committed Th2 cells. Ectopic expression of GATA3 via retrovirus did not overcome IFN-alpha/beta-mediated inhibition of Th2 commitment. Thus, we demonstrate a novel role for IFN-alpha/beta in blocking Th2 cells, suggesting its potential as a promising therapy for atopy and asthma.

Regulation of effector and memory T-cell functions by type I interferon.

Type I interferon (IFN-α/ß) is comprised of a family of highly related molecules that exert potent antiviral activity by interfering with virus replication and spread. IFN-α/ß secretion is tightly regulated through pathogen sensing pathways that are operative in most somatic cells. However, specialized antigen-presenting plasmacytoid dendritic cells are uniquely equipped with the capacity to secrete extremely high levels of IFN-α/ß, suggesting a key role for this cytokine in priming adaptive T-cell responses. Recent studies in both mice and humans have demonstrated a role for IFN-α/ß in directly influencing the fate of both CD4(+) and CD8(+) T cells during the initial phases of antigen recognition. As such, IFN-α/ß, among other innate cytokines, is considered an important 'third signal' that shapes the effector and memory T-cell pool. Moreover, IFN-α/ß also serves as a counter-regulator of T helper type 2 and type 17 responses, which may be important in the treatment of atopy and autoimmunity, and in the development of novel vaccine adjuvants.

Overexpression of the dynein light chain km23-1 in human ovarian carcinoma cells inhibits tumor formation in vivo and causes mitotic delay at prometaphase/metaphase.

km23-1 is a dynein light chain that was identified as a TGFß receptor-interacting protein. To investigate whether km23-1 controls human ovarian carcinoma cell (HOCC) growth, we established a tet-off inducible expression system in SKOV-3 cells in which the expression of km23-1 is induced upon doxycycline removal. We found that forced expression of km23-1 inhibited both anchorage-dependent and anchorage-independent growth of SKOV-3 cells. More importantly, induction of km23-1 expression substantially reduced the tumorigenicity of SKOV-3 cells in a xenograft model in vivo. Fluorescence-activated cell sorting analysis of SKOV-3 and IGROV-1 HOCCs demonstrated that the cells were accumulating at G2/M. Phospho-MEK, phospho-ERK and cyclin B1 were elevated, as was the mitotic index, suggesting that km23-1 suppresses HOCCs growth by inducing a mitotic delay. Immunofluorescence analyses demonstrated that the cells were accumulating at prometaphase/metaphase with increases in multipolar and multinucleated cells. Further, although the mitotic spindle assembly checkpoint protein BubR1 was present at the prometaphase kinetochore in Dox+/- cells, it was inappropriately retained at the metaphase kinetochore in Dox- cells. Thus, the mechanism by which high levels of km23-1 suppress ovarian carcinoma growth in vitro and inhibit ovary tumor formation in vivo appears to involve a BubR1-related mitotic delay.

The complete mitochondrial genome sequence of the Canada goose (Branta canadensis).

The Canada goose (Branta canadensis) entire mitochondrial genome of a bird from Western Pennsylvania has 16,760 bp (GenBank accession number NC 007011) and has been analyzed for gene locations, length, start codon and stop codons. This genome from a bird harvested during the non-migratory season is the REFSEQ and the haplotype is designated GCC-A. There are two rRNAs, 22 tRNAs, 13 protein-coding regions, and 1 displacement loop region. The base composition of mtDNA was A (30.2%), G (15.1%), C (32.1%), and T (22.6%), so the percentage of A and T (52.8%) was slightly higher than G and C. All genes except ND6 and eight tRNA genes (Gln, Ala, Asn, Cys, Tyr, Ser, Pro and Glu) are encoded on the heavy strand. The gene arrangement is the same as most birds and differs from mammals by an inversion of the mtDNA at the connection between the D-loop and the ND5 junctions.