PMID: 12600824;Abstract:
β-Defensin is one of the major host defense shields produced by various tissues and organs against microbial infection. To date, four human β-defensins (DEFBs) gene products that share a consensus six-cysteine motif have been discovered. The hidden Markov model (HMM) profile was constructed from the common features of those known β-defensin peptides to search for additional novel DEFB genes. A genome-wide search of the profile against ORFeome-based peptide databases (e.g., Ensembl project) led to the identification of six new DEFB members that also shared the conserved six-cysteine motif. Phylogenetic analysis supported a close relationship of these six new members with existing DEFB genes. Polymerase Chain Reaction studies of human tissue cDNA panels confirmed the expression of all six novel DEFB genes in various tissues. Two of them, DEFB106 and DEFB109, were expressed in the lung. A pilot study with cRNA probes for in situ hybridization and a synthetic propeptide for the functional characterization demonstrated the tissue-/ cell-specific expression and the strong antimicrobial activity of DEFB106. These results support the utility of ORFeome-based HMM search in gene discovery for members of a specific gene family. The novel DEFB genes identified in this study may significantly contribute to overall antimicrobial host defenses.
PMID: 21531775;PMCID: PMC3129903;Abstract:
Exposure to environmental pollutants has been linked to various airway diseases and disease exacerbations. Almost all chronic airway diseases uch as chronic obstructive pulmonary disease and asthma are aused by complicated interactions between gene and environment. ne of the major hallmarks of those diseases is airway mucus verproduction (MO). Excessive mucus causes airway obstruction and significantly increases morbidity and mortality. Metals are major components of environmental particulate matters (PM). Among them, vanadium has been suggested to play an important role in PM-induced mucin production. Vanadium pentoxide (V2O5) is the most common commercial source of vanadium, and it has been associated with occupational chronic bronchitis and asthma, both of which are MO diseases. However, the underlying mechanism is not entirely clear. In this study, we used both in vitro and in vivo models to demonstrate the robust inductions of mucin production by V2O5. Furthermore, the follow-up mechanistic study revealed a novel v-raf-1 murine leukemia viral oncogene homolog 1-IKK-NF-κB pathway that mediated V2O5- induced mucin production. Most interestingly, the reactive oxygen species and the classical mucin-inducing epidermal growth factor receptor (EGFR)-MAPK pathway appeared not to be involved in this process. Thus the V2O5-induced mucin production may represent a novel EGFR-MAPK-independent and environmental toxicant-associated MO model. Complete elucidation of the signaling pathway in this model will not only facilitate the development of the treatment for V2O5-associated occupational diseases but also advance our understanding on the EGFR-independent mucin production in other chronic airway diseases. © 2011 the American Physiological Society.
PMID: 11587997;Abstract:
Using a BLAST-searching approach, we identified a mouse expressed sequence tag (EST) clone (AA038672) showing great similarity to the 3′ end of the human MUC5B gene. The clone was named "3pmmuc5b-1" after complete nucleotide sequencing (Genbank Accession, AF369933). A subsequent search of the mouse genome database with the 3pmmuc5b-1 sequence identified two overlapping genomic clones (AC020817 and AC020794) that contained the sequence of both 3pmmuc5b-1 and the mouse Muc5ac gene. Like their human homologs, the genomic order of the mouse Muc genes is 5′-Muc5ac-Muc5b-3′. These results suggest that the newly identified EST clone, 3pmmuc5b-1, is part of the 3′ portion of the mouse Muc5b gene. In situ hybridization demonstrated that this putative mouse Muc5b message was expressed in a restricted manner in the sublingual gland region of the tongue and the submucosal gland region of the mouse trachea in a normal animal. However, the gene expression was greatly enhanced in airway surface epithelium and the submucosal gland region in ovalbumin-induced asthmatic mice. These results were consistent with previous studies of human airway tissues. We therefore conclude that this newly cloned mouse Muc5b gene could be used as a marker for studying aberrant mucin gene expression in mouse models of various airway diseases.
Abstract:
Chronic lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis are characterized by persistent airway inflammation and the overproduction of mucus in airways. So-called "goblet (mucous) cell metaplasia/hyperplasia" is the pathologic feature in these diseased airways, in which the normal mucociliary epithelium is replaced by goblet/mucous cells. The nature of the goblet/mucous cell population which arises in these diseased airways is unknown. Our recent studies have shown that trans-differentiation of surface epithelial cells occurs so that they express the submucosal gland-type mucin gene, MUC5B , in addition to a general elevation of all mucin gene products in surface epithelial cells as well as in the submucosal area. In contrast to MUC5B , the surface type of mucin gene, MUC5AC , is restrictedly expressed in the surface epithelium. Using a panel of cytokines - interleukin (IL)-1a, -1ß, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -13, -15, -16, -17, -18, and -19, and tumor necrosis factor-a - we have found to our surprise that only IL-6 and -7 can directly stimulate both MUC5AC and MUC5B expression in well-differentiated and polarized primary human airway epithelial cell cultures. Other cytokines, such as the Th2 type IL-4, -5, -9, and -13, cannot. Inhibitor and signaling transduction studies revealed the presence of an IL-6 paracrine/autocrine loop and the dependence on extracellular signal-regulated kinase signaling activation in IL-17-stimulated mucin gene expression. Further studies are needed to connect cytokine-based mucin gene expression and the trans-differentiation phenomenon in airway diseases. © 2006 Taylor & Francis.
