Expression of MATE1, P-gp, OCTN1 and OCTN2, in epithelial and immune cells in the lung of COPD and healthy individuals.

BACKGROUND: Several inhaled drugs are dependent on organic cation transporters to cross cell membranes. To further evaluate their potential to impact on inhaled drug disposition, the localization of MATE1, P-gp, OCTN1 and OCTN2 were investigated in human lung. METHODS: Transporter proteins were analysed by immunohistochemistry in lung tissue from healthy subjects and COPD patients. Transporter mRNA was analysed by qPCR in lung tissue and in bronchoalveolar lavage (BAL) cells from smokers and non-smokers. RESULTS: We demonstrate for the first time MATE1 protein expression in the lung with localization to the apical side of bronchial and bronchiolar epithelial cells. Interestingly, MATE1 was strongly expressed in alveolar macrophages as demonstrated both in lung tissue and in BAL cells, and in inflammatory cells including CD3 positive T cells. P-gp, OCTN1 and OCTN2 were also expressed in the alveolar epithelial cells and in inflammatory cells including alveolar macrophages. In BAL cells from smokers, MATE1 and P-gp mRNA expression was significantly lower compared to cells from non-smokers whereas no difference was observed between COPD patients and healthy subjects. THP-1 cells were evaluated as a model for alveolar macrophages but did not reflect the transporter expression observed in BAL cells. CONCLUSIONS: We conclude that MATE1, P-gp, OCTN1 and OCTN2 are expressed in pulmonary lung epithelium, in alveolar macrophages and in other inflammatory cells. This is important to consider in the development of drugs treating pulmonary disease as the transporters may impact drug disposition in the lung and consequently affect pharmacological efficacy and toxicity.

Airway epithelial cell differentiation during lung organogenesis requires C/EBPα and C/EBPß.

BACKGROUND: CCAAT/enhancer-binding protein (C/EBP)α is crucial for lung development and differentiation of the pulmonary epithelium. Conversely, no lung defects have been observed in C/EBPß-deficient mice, although C/EBPß trans-activate pulmonary genes by binding to virtually identical DNA-sequences as C/EBPα. Thus, the pulmonary phenotype of mice lacking C/EBPß could be explained by functional replacement with C/EBPα. We investigated whether C/EBPα and C/EBPß have overlapping functions in regulating lung epithelial differentiation during organogenesis. Epithelial differentiation was assessed in mice with a lung epithelial-specific (SFTPC-Cre-mediated) deletion of C/EBPα (Cebpa(ΔLE) ), C/EBPß (Cebpb(ΔLE) ), or both genes (Cebpa(ΔLE) ; Cebpb(ΔLE) ). RESULTS: Both Cebpa(ΔLE) mice and Cebpa(ΔLE) ; Cebpb(ΔLE) mice demonstrated severe pulmonary immaturity compared to wild-type littermates, while no differences in lung histology or epithelial differentiation were observed in Cebpb(ΔLE) mice. In contrast to Cebpa(ΔLE) mice, Cebpa(ΔLE) ; Cebpb(ΔLE) mice also displayed undifferentiated Clara cells with markedly impaired protein and mRNA expression of Clara cell secretory protein (SCGB1A1), compared to wild-type littermates. In addition, ectopic mucus-producing cells were observed in the conducting airways of Cebpa(ΔLE) ; Cebpb(ΔLE) mice. CONCLUSIONS: Our findings demonstrate that C/EBPα and C/EBPß play pivotal, and partly overlapping roles in determining airway epithelial differentiation, with possible implications for tissue regeneration in lung homeostasis and disease.

Lung epithelial-C/EBPß contributes to LPS-induced inflammation and its suppression by formoterol.

The inflammatory processes associated with pulmonary disorders remains incompletely understood. CCAAT/enhancer-binding protein (C/EBP)ß is implicated in inflammatory lung disorders as well as in ß(2)-adrenoceptor signaling. We hypothesized that C/EBPß in the lung epithelium contributes to lipopolysaccharide (LPS)-induced airway neutrophilia and expression of neutrophil chemoattractant chemokine (C-X-C) motif ligand (CXCL)1, as well as the suppressive effects of long-acting ß(2)-agonists (LABAs) and glucocorticoids (GCs). To investigate this, mice with a lung epithelial-specific deletion of C/EBPß (Cebpb(ΔLE)) and control littermates (Cebpb(fl/fl)) were pre-treated with a LABA, formoterol and/or a GC, budesonide, and challenged with LPS. Inflammatory cell recruitment in bronchoalveolar lavage (BAL) fluid and pulmonary expression of inflammatory mediators were investigated. In addition, the ability of formoterol to increase C/EBP transactivation was assessed in vitro. LPS-challenged Cebpb(ΔLE) mice exhibited fewer BAL neutrophils and lower pulmonary expression of CXCL1 versus Cebpb(fl/fl) mice. Suppression of LPS-induced neutrophilia by formoterol was impaired in Cebpb(ΔLE) mice and Cxcl1 expression was increased. However, suppression of the neutrophilia by budesonide with/without formoterol was preserved. Further studies indicated that C/EBP transactivation was increased by the cAMP elevating agent forskolin and formoterol in a ß(2)-adrenoceptor dependent manner. Thus, C/EBPß in the lung epithelium contributes to LPS-induced CXCL1 expression and airway neutrophilia as well as to the suppressive effects of formoterol. Reduced C/EBPß activity, observed in smokers with chronic obstructive pulmonary disease, may impair the responsiveness to LABAs when used without GCs.

Lung epithelial CCAAT/enhancer-binding protein-ß is necessary for the integrity of inflammatory responses to cigarette smoke.

RATIONALE: Cigarette smoke is the major cause of chronic obstructive pulmonary disease and lung cancer. The mechanisms by which smoking induces pulmonary dysfunction are complex, involving stress from toxic components and inflammatory responses. Although CCCAAT/enhancer-binding protein (C/EBP)-ß is known as a key intracellular regulator of inflammatory signaling, its role in pulmonary inflammation has not been established. OBJECTIVES: To characterize the role of C/EBPß in the airway epithelial response to cigarette smoke. METHODS: mRNA expression in the airway epithelium of current, former, and never-smokers, and in in vitro cigarette smoke extract-treated primary human airway epithelial cells, was analyzed by microarray and quantitative real-time polymerase chain reaction, respectively. Mice with lung epithelial-specific inactivation of C/EBPß were generated and exposed to cigarette smoke for 4 or 11 days. Lung histology, bronchoalveolar lavage cell differentials, and expression of inflammatory and innate immune mediators in the lungs were assessed. MEASUREMENTS AND MAIN RESULTS: C/EBPß was significantly down-regulated in the airway epithelium of both current and former smokers compared with never-smokers, and in cigarette smoke-treated primary human airway epithelial cells in vitro. Cigarette smoke-exposed mice with a lung epithelial-specific inactivation of C/EBPß displayed blunted respiratory neutrophil influx and compromised induction of neutrophil chemoattractants growth-regulated oncogene-α, macrophage inflammatory protein-1γ, granulocyte colony-stimulating factor, and serum amyloid A 3 and proinflammatory cytokines tumor necrosis factor-α and interleukin-1ß, compared with smoke-exposed controls. Inhibition of C/EBPß in human airway cells in vitro caused a similarly compromised response to smoke. CONCLUSION: Our data suggest a previously unknown role for C/EBPß and the airway epithelium in mediating inflammatory and innate immune responses to cigarette smoke.

Heart failure in childhood cancer survivors-a systematic review protocol.

BACKGROUND: Over the past decades, the survival rate for childhood cancer has greatly improved. However, the risk of late cardiac complications after cancer treatment remains high. Previous studies have shown that the risk for heart failure among childhood cancer survivors is significantly higher than that observed in varying control populations. The aim of this systematic review is to identify, critically appraise, and synthesize existing population-based studies reporting on the frequency of heart failure, both the incidence and prevalence, that may develop after treatment for childhood cancer. METHOD: The following databases will be searched from their inception date until May 17, 2021: MEDLINE, Embase, Scopus, CINAHL, CAB International, AMED, Global Health, PsycINFO, Web of Science, and Google Scholar. Population-based studies reporting on the incidence and/or prevalence of heart failure after the treatment of any type of childhood cancer will be included. The screening of articles, data extraction, and quality assessment will be performed independently by two reviewers. The quality and risk of bias in the included studies will be assessed by using the Effective Public Health Practice Project tool. A narrative synthesis of the extracted data will be carried out, and for studies that are sufficiently homogenous, a meta-analysis using random-effects models will be performed. DISCUSSION: This systematic review will provide a clearer picture of the epidemiology of heart failure after the treatment of childhood cancer. The collected data will be of value for future childhood cancer treatment protocols and will offer guidance for posttreatment cardiac surveillance among survivors. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42021247622 . Registered on April 28, 2021. This protocol follows the structure of the recommendation of the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P).

What is important for people with nontuberculous mycobacterial disease? An EMBARC-ELF patient survey.

Patients' experiences of NTM pulmonary disease highlight important and unmet needs for better pharmacological treatment and education of medical staff https://bit.ly/3mjrlwh.

ß-catenin regulates mesenchymal progenitor cell differentiation during hepatogenesis.

BACKGROUND: Understanding the pathways regulating mesenchymal progenitor cell fate during hepatogenesis may provide insight into postnatal liver injury or liver bioengineering. While ß-Catenin has been implicated in the proliferation of fetal hepatic epithelial progenitor cells, its role in mesenchymal precursors during hepatogenesis has not been established. MATERIALS AND METHODS: We used a murine model of conditional deletion of ß-Catenin in mesenchyme using the Dermo1 locus (ß-Catenin(Dermo1)) to characterize the role of ß-Catenin in liver mesenchyme during hepatogenesis. RESULTS: Lineage tracing using a LacZ reporter indicates that both hepatic stellate cells and pericytes derive from mesenchymal Dermo1 expressing precursor cells. Compared to control littermate livers, ß-Catenin(Dermo1) embryonic livers are smaller and filled with dilated sinusoids. While the fraction of mesenchymally-derived cells in ß-Catenin(Dermo1) embryos is unchanged compared to littermate controls, there is an increase in the expression of the mesenchymal markers, DESMIN, α-SMA, and extracellular deposition of COLLAGEN type I, particularly concentrated around dilated sinusoids. Analysis of the endothelial cell compartment in ß-Catenin(Dermo1)/Flk1(lacZ) embryos revealed a marked reorganization of the intrahepatic vasculature. Analysis of various markers for the endodermally-derived hepatoblast population revealed marked alterations in the spatial expression pattern of pan-cytokeratin but not E-cadherin, or albumin. ß-Catenin(Dermo1) phenocopies mesenchymal deletion of Pitx2, a known regulator of hepatic mesenchymal differentiation both during both organogenesis and postnatal injury. CONCLUSIONS: Our data implicate mesenchymal ß-Catenin signaling pathway in the differentiation of liver mesenchymal progenitor cells during organogenesis, possibly via Pitx2. Hepatic mesenchymal ß-Catenin signaling, in turn, modulates the development of both endothelium and endodermally-derived hepatoblasts, presumably via other downstream paracrine pathways.

Differential regulation of estrogen receptor (ER)alpha and ERbeta in primate mammary gland.

Estrogen, mainly estradiol (E2), and progesterone (P) are essential for the growth and differentiation of the breast, but their roles in breast cancer are highly debated. To understand how E2 and P influence cell proliferation and differentiation, it is essential to know how their receptors are regulated. Because of limited tissue availability, little is known about regulation of the two estrogen receptors (ERalpha and ERbeta) and the two progesterone receptor isoforms (PR-A and PR-B) in the normal human breast. What we know comes from rodent studies, which are not always pertinent for the human breast. We report now on regulation of gonadal hormone receptors during the menstrual cycle, pregnancy, and lactation in rhesus monkey mammary gland and on the relationship of these receptors to proliferation. We found that ERalpha but not ERbeta is down-regulated when E2 levels increase and when cells enter the cell cycle. PR-B but not PR-A is expressed in proliferating cells. Thus under normal conditions, the ratio of ERalpha to ERbeta in the breast depends on plasma concentrations of E2. Elevated expression of ERalpha (as occurs in postmenopausal women) is a normal response to loss of E2 and indicates nonproliferating cells. As selective receptor ligands become available, they will be helpful in delineation of the functions of these receptors.

Gpr116 Receptor Regulates Distinctive Functions in Pneumocytes and Vascular Endothelium.

Despite its known expression in both the vascular endothelium and the lung epithelium, until recently the physiological role of the adhesion receptor Gpr116/ADGRF5 has remained elusive. We generated a new mouse model of constitutive Gpr116 inactivation, with a large genetic deletion encompassing exon 4 to exon 21 of the Gpr116 gene. This model allowed us to confirm recent results defining Gpr116 as necessary regulator of surfactant homeostasis. The loss of Gpr116 provokes an early accumulation of surfactant in the lungs, followed by a massive infiltration of macrophages, and eventually progresses into an emphysema-like pathology. Further analysis of this knockout model revealed cerebral vascular leakage, beginning at around 1.5 months of age. Additionally, endothelial-specific deletion of Gpr116 resulted in a significant increase of the brain vascular leakage. Mice devoid of Gpr116 developed an anatomically normal and largely functional vascular network, surprisingly exhibited an attenuated pathological retinal vascular response in a model of oxygen-induced retinopathy. These data suggest that Gpr116 modulates endothelial properties, a previously unappreciated function despite the pan-vascular expression of this receptor. Our results support the key pulmonary function of Gpr116 and describe a new role in the central nervous system vasculature.

A method for generating pulmonary neutrophilia using aerosolized lipopolysaccharide.

Acute lung injury (ALI) is a severe disease characterized by alveolar neutrophilia, with limited treatment options and high mortality. Experimental models of ALI are key in enhancing our understanding of disease pathogenesis. Lipopolysaccharide (LPS) derived from gram positive bacteria induces neutrophilic inflammation in the airways and lung parenchyma of mice. Efficient pulmonary delivery of compounds such as LPS is, however, difficult to achieve. In the approach described here, pulmonary delivery in mice is achieved by challenge to aerosolized Pseudomonas aeruginosa LPS. Dissolved LPS was aerosolized by a nebulizer connected to compressed air. Mice were exposed to a continuous flow of LPS aerosol in a Plexiglas box for 10 min, followed by 2 min conditioning after the aerosol was discontinued. Tracheal intubation and subsequent bronchoalveolar lavage, followed by formalin perfusion was next performed, which allows for characterization of the sterile pulmonary inflammation. Aerosolized LPS generates a pulmonary inflammation characterized by alveolar neutrophilia, detected in bronchoalveolar lavage and by histological assessment. This technique can be set up at a small cost with few appliances, and requires minimal training and expertise. The exposure system can thus be routinely performed at any laboratory, with the potential to enhance our understanding of lung pathology.

Gene expression analysis of membrane transporters and drug-metabolizing enzymes in the lung of healthy and COPD subjects.

This study describes for the first time the expression levels of genes encoding membrane transporters and drug-metabolizing enzymes in the lungs of ex-smoking patients with chronic obstructive pulmonary disease (COPD). Membrane transporters and drug-metabolizing enzymes are key determinants of drug uptake, metabolism, and elimination for systemically administered as well as inhaled drugs, with consequent influence on clinical efficacy and patient safety. In this study, while no difference in gene expression was found between healthy and COPD subjects, we identified a significant regional difference in mRNA expression of both membrane transporters and drug-metabolizing enzymes between central and peripheral tissue in both healthy and COPD subjects. The majority of the differentially expressed genes were higher expressed in the central airways such as the transporters SLC2A1 (GLUT1), SLC28A3 (CNT3), and SLC22A4 (OCTN1) and the drug-metabolizing enzymes GSTZ1, GSTO2, and CYP2F1. Together, this increased knowledge of local pharmacokinetics in diseased and normal lung may improve modeling of clinical outcomes of new chemical entities intended for inhalation therapy delivered to COPD patients. In addition, based on the similarities between COPD and healthy subjects regarding gene expression of membrane transporters and drug-metabolizing enzymes, our results suggest that clinical pharmacological studies in healthy volunteers could be a valid model of COPD patients regarding drug disposition of inhaled drugs in terms of drug metabolism and drug transporters.

Human enterovirus species B in ileocecal Crohn's disease.

OBJECTIVES: Advanced ileocecal Crohn's disease (ICD) is characterized by strictures, inflammation in the enteric nervous system (myenteric plexitis), and a high frequency of NOD2 mutations. Recent findings implicate a role of NOD2 and another CD susceptibility gene, ATG16L1, in the host response against single-stranded RNA (ssRNA) viruses. However, the role of viruses in CD is unknown. We hypothesized that human enterovirus species B (HEV-B), which are ssRNA viruses with dual tropism both for the intestinal epithelium and the nervous system, could play a role in ICD. METHODS: We used immunohistochemistry and in situ hybridization to study the general presence of HEV-B and the presence of the two HEV-B subspecies, Coxsackie B virus (CBV) and Echovirus, in ileocecal resections from 9 children with advanced, stricturing ICD and 6 patients with volvulus, and in intestinal biopsies from 15 CD patients at the time of diagnosis. RESULTS: All patients with ICD had disease-associated polymorphisms in NOD2 or ATG16L1. Positive staining for HEV-B was detected both in the mucosa and in myenteric nerve ganglia in all ICD patients, but in none of the volvulus patients. Expression of the cellular receptor for CBV, CAR, was detected in nerve cell ganglia. CONCLUSIONS: The common presence of HEV-B in the mucosa and enteric nervous system of ICD patients in this small cohort is a novel finding that warrants further investigation to analyze whether HEV-B has a role in disease onset or progress. The presence of CAR in myenteric nerve cell ganglia provides a possible route of entry for CBV into the enteric nervous system.

A Relationship between Epithelial Maturation, Bronchopulmonary Dysplasia, and Chronic Obstructive Pulmonary Disease.

Premature infants frequently develop bronchopulmonary dysplasia (BPD). Lung immaturity and impaired epithelial differentiation contribute together with invasive oxygen treatment to BPD onset and disease progression. Substantial evidence suggests that prematurity is associated with long term pulmonary consequences. Moreover, there is increasing concern that lung immaturity at birth may increase the risk of developing chronic obstructive pulmonary disease (COPD). The mechanisms contributing to this phenomenon remains unknown, largely as a consequence of inadequate experimental models and clinical follow-up studies. Recent evidence suggests that defective transcriptional regulation of epithelial differentiation and maturation may contribute to BPD pathogenesis as well as early onset of COPD. The transcriptional regulators CCAAT/enhancer-binding protein (C/EBP)α and C/EBPß, SMAD family member (Smad)3, GATA binding protein (GATA)6, and NK2 homeobox (NKX)2-1 are reported to be involved in processes contributing to pathogenesis of both BPD and COPD. Increased knowledge of the mechanisms contributing to early onset COPD among BPD survivors could translate into improved treatment strategies and reduced frequency of respiratory disorders among adult survivors of BPD. In this paper, we introduce critical transcriptional regulators in epithelial differentiation and summarize the current knowledge on the contribution of impaired epithelial maturation to the pathogenesis of inflammatory lung disorders.

Chronic respiratory aeroallergen exposure in mice induces epithelial-mesenchymal transition in the large airways.

Chronic allergic asthma is characterized by Th2-polarized inflammation and leads to airway remodeling and fibrosis but the mechanisms involved are not clear. To determine whether epithelial-mesenchymal transition contributes to airway remodeling in asthma, we induced allergic airway inflammation in mice by intranasal administration of house dust mite (HDM) extract for up to 15 consecutive weeks. We report that respiratory exposure to HDM led to significant airway inflammation and thickening of the smooth muscle layer in the wall of the large airways. Transforming growth factor beta-1 (TGF-ß1) levels increased in mouse airways while epithelial cells lost expression of E-cadherin and occludin and gained expression of the mesenchymal proteins vimentin, alpha-smooth muscle actin (α-SMA) and pro-collagen I. We also observed increased expression and nuclear translocation of Snail1, a transcriptional repressor of E-cadherin and a potent inducer of EMT, in the airway epithelial cells of HDM-exposed mice. Furthermore, fate-mapping studies revealed migration of airway epithelial cells into the sub-epithelial regions of the airway wall. These results show the contribution of EMT to airway remodeling in chronic asthma-like inflammation and suggest that Th2-polarized airway inflammation can trigger invasion of epithelial cells into the subepithelial regions of the airway wall where they contribute to fibrosis, demonstrating a previously unknown plasticity of the airway epithelium in allergic airway disease.

Fibroblast growth factor 10 is critical for liver growth during embryogenesis and controls hepatoblast survival via beta-catenin activation.

UNLABELLED: Fibroblast growth factor (FGF) signaling and beta-catenin activation have been shown to be crucial for early embryonic liver development. This study determined the significance of FGF10-mediated signaling in a murine embryonic liver progenitor cell population as well as its relation to beta-catenin activation. We observed that Fgf10(-/-) and Fgfr2b(-/-) mouse embryonic livers are smaller than wild-type livers; Fgf10(-/-) livers exhibit diminished proliferation of hepatoblasts. A comparison of beta-galactosidase activity as a readout of Fgf10 expression in Fgf10(+/LacZ) mice and of beta-catenin activation in TOPGAL mice, demonstrated peak Fgf10 expression from E9 to E13.5 coinciding with peak beta-catenin activation. Flow cytometric isolation and marker gene expression analysis of LacZ(+) cells from E13.5 Fgf10(+/LacZ) and TOPGAL livers, respectively, revealed that Fgf10 expression and beta-catenin signaling occur distinctly in stellate/myofibroblastic cells and hepatoblasts, respectively. Moreover, hepatoblasts express Fgfr2b, which strongly suggests they can respond to recombinant FGF10 produced by stellate cells. Fgfr2b(-/-)/TOPGAL(+/+) embryonic livers displayed less beta-galactosidase activity than livers of Fgfr2b(+/+)/TOPGAL(+/+) littermates. In addition, cultures of whole liver explants in Matrigel or cell in suspension from E12.5 TOPGAL(+/+)mice displayed a marked increase in beta-galactosidase activity and cell survival upon treatment with recombinant FGF10, indicating that FGFR (most likely FGFR2B) activation is upstream of beta-catenin signaling and promote hepatoblast survival. CONCLUSION: Embryonic stellate/myofibroblastic cells promote beta-catenin activation in and survival of hepatoblasts via FGF10-mediated signaling. We suggest a role for stellate/myofibroblastic FGF10 within the liver stem cell niche in supporting the proliferating hepatoblast.

Ectopic expression of C/EBPalpha in the lung epithelium disrupts late lung development.

The lung develops from the endoderm through a process of branching morphogenesis. This process is highly active during the pseudoglandular stage of lung development and continues into the canalicular stage, resulting in the formation of terminal sacs. CCAAT/enhancer binding proteins (C/EBPs) are transcription factors regulating central aspects of differentiation and proliferation. We report here the developmental expression of C/EBPalpha, -beta, and -delta in the lung. C/EBPalpha exhibits a dynamic expression pattern and is first detected during the late pseudoglandular stage. At this stage, expression is observed in a subset of epithelial cells in the distal parts of the branching tubules. The expression of C/EBPalpha is confined to nonproliferating cells. To examine the role of C/EBPalpha in lung development, we generated transgenic mice ectopically expressing C/EBPalpha in the lung epithelium using the human surfactant protein C promoter. Lungs from these mice were of normal size but exhibited a phenotype characterized by fewer and larger developing epithelial tubules, indicating that the branching process was affected. No effects on overall proliferation or cellular differentiation were observed. When this phenotype was compared with that of mice carrying a targeted mutation of the Cebpa gene, the Cebpa-/- mice exhibited a similar developmental phenotype. In conclusion, our results show a role for C/EBPalpha in lung development and suggest a function in the later stages of lung branching morphogenesis.

Glucocorticoids increase C/EBPbeta activity in the lung epithelium via phosphorylation.

Glucocorticoids are widely prescribed anti-inflammatory drugs used for the treatment of many inflammatory lung disorders. However, much still remains unknown about their molecular mechanisms of action. We have previously shown that glucocorticoid-induced transcription in the lung epithelial cell line NCI-H441 is mediated via C/EBP sites in the promoters of target genes, and is likely to involve the transcription factors C/EBPbeta and C/EBPdelta. Here, we report that C/EBPbeta is the most active C/EBP-factor in both human and mouse lung epithelium and that glucocorticoids induce DNA binding of C/EBPbeta in cultured primary mouse lung epithelial cells. Mechanistic studies in H441 cells revealed that glucocorticoids, acting via the glucocorticoid receptor, increase C/EBPbeta binding starting 10 min after stimulation. The mechanism is independent of de novo protein synthesis and involves phosphorylation of C/EBPbeta at Thr(235). Together this shows that glucocorticoids increase DNA-binding activity of C/EBPbeta via post-translational mechanism(s) involving phosphorylation.

Synergistic transactivation of the differentiation-dependent lung gene Clara cell secretory protein (secretoglobin 1a1) by the basic region leucine zipper factor CCAAT/enhancer-binding protein alpha and the homeodomain factor Nkx2.1/thyroid transcription factor-1.

The basic region-leucine zipper transcription factor CCAAT/enhancer-binding protein alpha (C/EBPalpha) and the homeodomain transcription factor Nkx2.1/thyroid transcription factor-1 are essential for normal lung morphogenesis. Nkx2.1 is expressed from the onset of lung development, whereas C/EBPalpha expression is turned on at later stages. The expression of C/EBPalpha correlates to the appearance of lung-specific proteins with differentiation-dependent expression patterns, such as the Clara cell secretory protein (secretoglobin 1a1 (Scgb1a1), CCSP). In this study, we demonstrate synergistic transactivation by C/EBPalpha and Nkx2.1 in the regulation of the CCSP gene. We show that the synergistic activity of C/EBPalpha and Nkx2.1 originates from cis-acting elements in the proximal promoter of CCSP and that the synergism is dependent on NH(2)-terminal transactivation domains of C/EBPalpha and Nkx2.1. Our results suggest that the cooperation of C/EBPalpha and Nkx2.1 is a major determinant for the high level, lung epithelial-specific expression of CCSP during the later stages of lung development and in the adult lung.