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Biomedical subjects

R Gropp

Publications and source records attributed to R Gropp.

8 recordsLinked to original sources
PubMed2001

Expression of human beta-defensin-1 promotes differentiation of keratinocytes.

Epithelial cells have been shown to express the antibiotic peptides human beta-defensins-1 and 2. While beta-defensin-2 is known to be up-regulated by bacterial factors and proinflammatory mediators, the expression of beta-defensin-1 does not appear to be affected by these mediators. To determine the regulation and function of beta-defensin-1 we analyzed its expression upon stimulation of inflammatory mediators in vitro and ex vivo. In immortalized human cell lines (HaCaT) and nasal polyps beta-defensin-1 was not induced upon incubation with bacteria or proinflammatory mediators, suggesting that the inertness of beta-defensin-1 expression levels is not the result of the shortcoming of HaCaT cells. As proliferation and regeneration play an important role at sites of inflammation, we examined the expression level of beta-defensin-1 in relation to the differentiation and proliferation of HaCaT cells. beta-defensin-1 mRNA levels remained low during proliferation but were highly induced upon differentiation. In contrast, beta-defensin-2 expression was unaffected under these conditions. To examine the function of beta-defensin-1 in cellular proliferation and differentiation processes beta-defensin-1 was overexpressed in keratinocytes. Protein expression analysis of the differentiation marker keratin 10 revealed that its expression is highly induced in the presence of increased concentrations of beta-defensin-1. Hence our data indicate that high expression of beta-defensin-1 promotes cell differentiation processes of keratinocytes.

Blotting, Western↗
PubMed2000

Differential expression of human alpha- and beta-defensins mRNA in gastrointestinal epithelia.

BACKGROUND: While defensins have received great attention for their role in bronchial innate immune defence, little is known about the expression levels of the four human epithelial defensins (HD5, HD6, hBD1 and hBD2) in the digestive tract. In this study we quantified the alpha- and beta-defensins mRNA in biopsies obtained from the gastrointestinal mucosa and identified the cells expressing the beta-defensin hBD1 mRNA in ileal mucosa. MATERIAL AND METHODS: Biopsies from human stomach (corpus and antrum), duodenum, jejunum, ileum and colon were analysed for their expression of alpha- and beta-defensins. The mRNA of defensins was quantified by semiquantitative reverse transcription-polymerase chain reaction. Cells expressing beta-defensin hBD1 mRNA were identified by in situ hybridization with 35S-labelled RNA probes in tissue sections of human ileum. RESULTS: The hBD1 mRNA was expressed at low levels with little variability throughout the gastrointestinal tract and was detected in all epithelial cells of ileal mucosa. HD5 and HD6 mRNA expression was restricted to the intestine and displayed high interindividual variability. The highest expression levels were observed in jejunum and ileum. Biopsies obtained from duodenum displayed low levels or no expression of HD5 and HD6. The expression level increased considerably in a biopsy obtained from a patient with acute coeliac sprue. In contrast, low levels were observed in a biopsy from a patient with coeliac sprue in remission. CONCLUSIONS: The expression levels of hBD1, HD5 and HD6 throughout the gastrointestinal tract are tissue and peptide specific and these defensins are expressed with high interindividual variability.

Anti-Infective Agents↗
PubMed2000

Expression of human alpha-defensin 5 (HD5) mRNA in nasal and bronchial epithelial cells.

BACKGROUND/AIMS: Human defensins are antibiotic peptides expressed in myeloid and epithelial cells. Human alpha-defensin 5 (HD5) has been detected in Paneth cell granules in the crypts of Lieberkühn and has recently been identified in the female reproductive tract. The aim of this study was to investigate the presence of HD5 mRNA in nasal and bronchial epithelial cells. METHODS/RESULTS: Semiquantitative reverse transcription polymerase chain reaction (RT-PCR) analysis showed that HD5 mRNA was expressed infrequently and to varying degrees in bronchial and nasal epithelial cells. In situ hybridisation resulted in a positive signal in the epithelial layer of nasal polyps. HD5 mRNA was locally restricted to a specific area of epithelial cells and also occurred in submucosal glands. CONCLUSIONS: HD5 mRNA expression in nasal and bronchial epithelial cells is rare and seemed to be locally induced. The results indicate that HD5 might play a role in innate defence in nasal and bronchial epithelia.

Base Sequence↗
PubMed1999

Epithelial defensins impair adenoviral infection: implication for adenovirus-mediated gene therapy.

Epithelial cells have been to participate actively in host defense by producing small cationic peptides called defensins. To investigate the biological activity of epithelial defensins in more detail, we expressed two defensins, hBD-1 and HD-5, in eukaryotic cell lines. Defensins were localized in the cytoplasm and in cell culture medium and exhibited strong microbicidal activity toward Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Moreover, our data indicate that the presence of defensins protected the cells from adenoviral infection. The presence of HD-5 or hBD-1 reduced the infectivity of Av1CF2 three- to fivefold. These results imply that defensins must be considered a serious obstacle whenever adenovirus is used to deliver genes to epithelial cells.

Adenoviridae↗
PubMed1995

Effects of upstream deletions on light- and oxygen-regulated bacterio-opsin gene expression in Halobacterium halobium.

The bacterio-opsin gene (bop) of Halobacterium halobium is located within a cluster with three other genes. Growth conditions of high light intensity and low oxygen tension induce bop gene cluster expression. To identify putative regulatory factor binding sites upstream of the bop gene, we have compared sequences upstream of the bop gene with the corresponding sequences from two other genes in the bop gene cluster. Conserved sequence motifs were observed which may mediate the effect of high light intensity and/or low oxygen tension on bop gene expression. Based on these motifs, a set of mutants was constructed which contained deletions upstream of the bop gene. These constructs were tested in a host strain where bop gene expression is independent of oxygen regulation and in another strain where it is regulated by oxygen and light. The minimal upstream sequence required for both light- and oxygen-regulated bop gene expression was determined to be 54 bp.

Bacteriorhodopsins↗
PubMed1992

Association of the halobacterial 7S RNA to the polysome correlates with expression of the membrane protein bacterioopsin.

The sedimentation behavior of the halobacterial 7S RNA and bacterioopsin mRNA was assessed after application of total cell lysates to sucrose gradients. These two RNAs cosedimented predominantly with membrane-bound polysomes, and the quantity of 7S RNA bound to the ribosomes was directly correlated with the expression of bacterioopsin. Puromycin treatment released the 7S RNA from the polysomes, indicating that it is transiently associated with protein translation. We suggest that halobacteria contain a signal-recognition-like particle involved in translation of membrane-associated proteins.

Amino Acid Sequence↗
PubMed1992

Expression of anchorin CII, a collagen-binding protein of the annexin family, in the developing chick embryo.

Expression of anchorin CII, a collagen-binding protein of the annexin family, was followed in the developing chick embryo using Northern and in situ hybridization and Western blotting. During chick somite development, anchorin CII mRNA was detected by Northern blotting as early as stage 11. At stage 24, anchorin mRNA accumulated in the anterior part of the somite sclerotome near the resegmentation line, as shown by in situ hybridization. The presence of anchorin CII protein during stages 11 to 20 was confirmed by Western blotting. In situ hybridization identified anchorin CII also in the otic vesicle adjacent to the site of contact with the statoacoustic ganglion and in the mandibular mesenchyme. The level of anchorin CII mRNA in differentiated hyaline cartilage, exemplified by sternal cartilage, was lower than that in differentiating somites or cultured chondrocytes. These findings are consistent with our notion that anchorin CII may be involved in cell-matrix interactions preceding chondrogenic differentiation events in the chick embryo. A significant level of anchorin CII mRNA and protein synthesis was also found in cultured myoblasts, but less than that in chondroblasts. This distribution pattern is different from that reported for a related protein, p34, or calpactin, the major protein substrate for tyrosine kinase phosphorylation in chick chondrocytes and fibroblasts. The results confirm suggestions from previous sequencing studies that anchorin CII and p34 are different proteins of the annexin/calpactin family.

Animals↗