Trefoil peptides promote restitution of wounded corneal epithelial cells

Trefoil Factor Family (TFF) Peptides and Their Diverse Molecular Functions in Mucus Barrier Protection and More: Changing the Paradigm

Trefoil factor family peptides (TFF1, TFF2, TFF3) are typically co-secreted together with mucins. Tff1 represents a gastric tumor suppressor gene in mice. TFFs are also synthesized in minute amounts in the immune and central nervous systems. In mucous epithelia, they support rapid repair by enhancing cell migration ("restitution") via their weak chemotactic and anti-apoptotic effects. For a long time, as a paradigm, this was considered as their major biological function. Within recent years, the formation of disulfide-linked heterodimers was documented for TFF1 and TFF3, e.g., with gastrokine-2 and IgG Fc binding protein (FCGBP). Furthermore, lectin activities were recognized as enabling binding to a lipopolysaccharide of Helicobacter pylori (TFF1, TFF3) or to a carbohydrate moiety of the mucin MUC6 (TFF2). Only recently, gastric TFF1 was demonstrated to occur predominantly in monomeric forms with an unusual free thiol group. Thus, a new picture emerged, pointing to diverse molecular functions for TFFs. Monomeric TFF1 might protect the gastric mucosa as a scavenger for extracellular reactive oxygen/nitrogen species. Whereas, the TFF2/MUC6 complex stabilizes the inner layer of the gastric mucus. In contrast, the TFF3-FCGBP heterodimer (and also TFF1-FCGBP) are likely part of the innate immune defense of mucous epithelia, preventing the infiltration of microorganisms.

Mucosal Mesenchymal Cells: Secondary Barrier and Peripheral Educator for the Gut Immune System

Stromal connective tissue contains mesenchymal cells, including fibroblasts and myofibroblasts, which line the tissue structure. However, it has been identified that the function of mesenchymal cells is not just structural-they also play critical roles in the creation and regulation of intestinal homeostasis. Thus, mucosal mesenchymal cells instruct intestinal immune cell education (or peripheral immune education) and epithelial cell differentiation thereby shaping the local environment of the mucosal immune system. Malfunction of the mesenchymal cell-mediated instruction system (e.g., fibrosis) leads to pathological conditions such as intestinal stricture.

Forced Trefoil Factor Family Peptide 3 (TFF3) Expression Reduces Growth, Viability, and Tumorigenicity of Human Retinoblastoma Cell Lines

Trefoil factor family (TFF) peptides have been shown to effect cell proliferation, apoptosis, migration and invasion of normal cells and various cancer cell lines. In the literature TFF peptides are controversially discussed as tumor suppressors and potential tumor progression factors. In the study presented, we investigated the effect of TFF3 overexpression on growth, viability, migration and tumorigenicity of the human retinoblastoma cell lines Y-79, WERI-Rb1, RBL-13 and RBL-15. As revealed by WST-1 and TUNEL assays as well as DAPI and BrdU cell counts, recombinant human TFF3 significantly lowers retinoblastoma cell viability and increases apoptosis levels. Transient TFF3 overexpression likewise significantly increases RB cell apoptosis. Stable, lentiviral TFF3 overexpression lowers retinoblastoma cell viability, proliferation and growth and significantly increases cell death in retinoblastoma cells. Blockage experiments using a broad-spectrum caspase inhibitor and capase-3 immunocytochemistry revealed the involvement of caspases in general and of caspase-3 in particular in TFF3 induced apoptosis in retinoblastoma cell lines. Soft agarose and in ovo chicken chorioallantoic membrane (CAM) assays revealed that TFF3 overexpression influences anchorage independent growth and significantly decreases the size of tumors forming from retinoblastoma cells. Our study demonstrates that forced TFF3 expression exerts a significant pro-apoptotic, anti-proliferative, and tumor suppressive effect in retinoblastoma cells, setting a starting point for new additive chemotherapeutic approaches in the treatment of retinoblastoma.

Protective effects of intestinal trefoil factor (ITF) on gastric mucosal epithelium through activation of extracellular signal-regulated kinase 1/2 (ERK1/2)

The rapid repair of gastric mucosa is critical upon exposure to injurious agents. Intestinal trefoil factor (ITF) is a member of the trefoil factor family domain peptides, which play an important role in the cytoprotection of gastric epithelium. However, the underlying molecular mechanisms that are responsible for ITF-induced gastric epithelial repair remain unclear. In the present study, we demonstrate that ITF enhances the proliferation and migration of GES-1 gastric endothelial cells in a dose- and time-dependent manner through the activation of extracellular signal-regulated kinase 1/2 (ERK1/2). Furthermore, the ITF-mediated protection of GES-1 cells from a NS398 (nonsteroidal anti-inflammatory drug) was dependent on the ERK1/2 signaling pathway. Taken together, the results provide a mechanistic explanation for ITF-mediated protection of gastric epithelial mucosa cells, suggesting that activation of the ERK1/2 signaling pathway may provide a new therapeutic strategy for repairing gastric injury.

Trefoil factor family protein 3 (TFF3) is present in cartilage during endochondral ossification in the developing mouse fetus

Trefoil factor family protein 3 (TFF3) is found in cartilage affected by osteoarthritis and septic arthritis, whereas no TFF3 presence is observed in healthy cartilage. During endochondral ossification, bone tissue replaces degenerating cartilage. There is no data about the role of TFF3 in this process. Our aim was to study the localization of TFF3 in cartilage during endochondral ossification in the mouse fetus. CD1 mouse fetuses, days 14-17, were isolated, fixed, and paraffin embedded. Fetuses were cut into 6μm sections, and processed for immunohistochemical staining with affinity purified polyclonal rabbit anti-TFF3 antibody. TFF3 was present in cartilage chondrocytes undergoing endochondral ossification, particularly in zone of proliferation, hypertrophy and calcification as well as in zone of cartilage degeneration during the monitored fetal period. Resting cartilage showed no presence of TFF3, while during endochondral ossification TFF3 localization showed an analogous pattern to that reported in cartilage affected by osteoarthritis and septic arthritis. Our data indicate that the role of TFF3 in these pathological conditions is similar to its role in the physiological process of endochondral ossification.

Trefoil factor 2 negatively regulates type 1 immunity against Toxoplasma gondii

IL-12-mediated type 1 inflammation confers host protection against the parasitic protozoan Toxoplasma gondii. However, production of IFN-γ, another type 1 inflammatory cytokine, also drives lethality from excessive injury to the intestinal epithelium. As mechanisms that restore epithelial barrier function following infection remain poorly understood, this study investigated the role of trefoil factor 2 (TFF2), a well-established regulator of mucosal tissue repair. Paradoxically, TFF2 antagonized IL-12 release from dendritic cells (DCs) and macrophages, which protected TFF2-deficient (TFF2(-/-)) mice from T. gondii pathogenesis. Dysregulated intestinal homeostasis in naive TFF2(-/-) mice correlated with increased IL-12/23p40 levels and enhanced T cell recruitment at baseline. Infected TFF2(-/-) mice displayed low rates of parasite replication and reduced gut immunopathology, whereas wild-type (WT) mice experienced disseminated infection and lethal ileitis. p38 MAPK activation and IL-12p70 production was more robust from TFF2(-/-)CD8+ DC compared with WT CD8+ DC and treatment of WT DC with rTFF2 suppressed TLR-induced IL-12/23p40 production. Neutralization of IFN-γ and IL-12 in TFF2(-/-) animals abrogated resistance shown by enhanced parasite replication and infection-induced morbidity. Hence, TFF2 regulated intestinal barrier function and type 1 cytokine release from myeloid phagocytes, which dictated the outcome of oral T. gondii infection in mice.

Trefoil factor family peptide 2 acts pro-proliferative and pro-apoptotic in the murine retina

Although expression of trefoil factor family (TFF) peptides has been reported in the brain, nothing is known about TFF expression in the retina. The aim of this study was to test whether TFF peptides are expressed in the murine retina and have any function here. In contrast to most tissues studied, where TFF1 and TFF3 are the predominant peptides, TFF2 is the only peptide expressed in the murine retina. Immunohistochemical studies on murine retinal sections indicate that cells of the ganglion cell layer are the retinal source for murine TFF2 (Tff2). In organotypic murine retina cell cultures recombinant TFF2 exerted a strong pro-apoptotic and pro-proliferative rather than an anti-apoptotic and anti-proliferating effect described in most human cancer cell lines investigated so far. In blockage experiments we were able to demonstrate that the pro-apoptotic effect of TFF2 is caspase-dependent. Western blot analysis of TFF2 treated retinal wholemount homogenates revealed significant reductions in the phosphorylation level of ERK and STAT3 proteins compared to basal conditions, suggesting that in the developing murine retina survival mechanism are down-regulated upon TFF2 administration. Our results suggest that during retinal cell death periods, requiring a tightly regulated balance between cell survival and cell death, TFF2 acts pro-proliferative and pro-apoptotic at least in developing mouse retinae cultured in vivo.

[Trefoil factor: from laboratory to clinic]

Trefoil factor (TFF) family is a group of peptides with one or several trefoil factor domains in their structure, which are highly conserved in evolution, and are characterized by heat and enzymatic digestion resistance. The mammalian TFFs have three members (TFF1-3), and the gastrointestinal tract and the airway system are major organs of their expression and secretion. At certain physiological conditions, with a tissue-specific distribution, TFF plays an important role in mucosal protection and wound healing. But in the malignant tissues, TFF is widely expressed, correlated strongly with the genesis, metastasis and invasion of tumor cells. These phenomena indicated that TFF may be a possible common mediator of oncogenic responses to different stimuli. The biological functions of TFF involve complex regulatory processes. Single chain TFF may activate cell membrane receptors and induce specific signaling transduction. On the other hand, TFF can form a complex with other proteins to exert its biological effects. In clinical medicine, TFF is primarily applied as drugs in the mucosal protection, in the prevention and the treatment of mucosal damage-related diseases and as pathological biomarkers of tumors. At present the first hand actions and the molecular mechanisms related to TFFs are still the major challenges in TFF research. Furthermore, the discovery of the naturally occurring complex of TFF and crystallins is highly valuable to the understanding of the biological functions and action mechanisms of TFF.

Trefoil factor 3 is induced during degenerative and inflammatory joint disease, activates matrix metalloproteinases, and enhances apoptosis of articular cartilage chondrocytes

OBJECTIVE

Trefoil factor 3 (TFF3, also known as intestinal trefoil factor) is a member of a family of protease-resistant peptides containing a highly conserved motif with 6 cysteine residues. Recent studies have shown that TFF3 is expressed in injured cornea, where it plays a role in corneal wound healing, but not in healthy cornea. Since cartilage and cornea have similar matrix properties, we undertook the present study to investigate whether TFF3 could induce anabolic functions in diseased articular cartilage.

METHODS

We used reverse transcriptase-polymerase chain reaction, Western blot analysis, and immunohistochemistry to measure the expression of TFF3 in healthy articular cartilage, osteoarthritis (OA)-affected articular cartilage, and septic arthritis-affected articular cartilage and to assess the effects of cytokines, bacterial products, and bacterial supernatants on TFF3 production. The effects of TFF3 on matrix metalloproteinase (MMP) production were measured by enzyme-linked immunosorbent assay, and effects on chondrocyte apoptosis were studied by caspase assay and annexin V assay.

RESULTS

Trefoil factors were not expressed in healthy human articular cartilage, but expression of TFF3 was highly up-regulated in the cartilage of patients with OA. These findings were confirmed in animal models of OA and septic arthritis, as well as in tumor necrosis factor alpha- and interleukin-1beta-treated primary human articular chondrocytes, revealing induction of Tff3/TFF3 under inflammatory conditions. Application of the recombinant TFF3 protein to cultured chondrocytes resulted in increased production of cartilage-degrading MMPs and increased chondrocyte apoptosis.

CONCLUSION

In this study using articular cartilage as a model, we demonstrated that TFF3 supports catabolic functions in diseased articular cartilage. These findings widen our knowledge of the functional spectrum of TFF peptides and demonstrate that TFF3 is a multifunctional trefoil factor with the ability to link inflammation with tissue remodeling processes in articular cartilage. Moreover, our data suggest that TFF3 is a factor in the pathogenesis of OA and septic arthritis.

Signal transduction and gene transcription induced by TFF3 in oral keratinocytes

Trefoil factor family 3 (TFF3) is secreted in saliva. The peptide improves the mechanical and chemical resistance of mucins, and it may act as a motility signal for oral keratinocytes during wound healing. This study aimed to identify novel functions of TFF3 in oral keratinocytes. To achieve this, we used phosphoprotein and messenger RNA (mRNA) arrays to compare TFF3-treated and untreated oral keratinocytes. Analysis of the phosphoprotein array indicated that TFF3 signals through the mitogen-activated protein kinases (MAPKs) c-Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK1/2), and through the phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB) pathway. Microarray analysis of mRNA showed that TFF3 stimulation induced changes in the expression of genes functionally related to cell death/survival, cell growth and proliferation, and cell movement. The reverse transcription-polymerase chain reaction (RT-PCR) results indicated that the transcription of some immediate-early genes (IEGs) was downregulated, whereas the IEGs FBJ osteosarkoma oncogene (FOS) and C-MYC binding protein (MYCBP2) were transiently upregulated by TFF3 stimulation. Together, the results of the arrays indicate that TFF3 is a modifying factor in pathways regulating cell survival, cell growth and proliferation, and cell migration of oral keratinocytes. Trefoil factor family 3 may therefore promote oral wound healing and it should be considered for the treatment of oral ulcerating diseases, or of other diseases.

Intestinal barrier dysfunction in inflammatory bowel diseases

The etiology of human inflammatory bowel diseases (IBDs) is believed to involve inappropriate host responses to the complex commensal microbial flora in the gut, although an altered commensal flora is not completely excluded. A multifunctional cellular and secreted barrier separates the microbial flora from host tissues. Altered function of this barrier remains a major largely unexplored pathway to IBD. Although there is evidence of barrier dysfunction in IBD, it remains unclear whether this is a primary contributor to disease or a consequence of mucosal inflammation. Recent evidence from animal models demonstrating that genetic defects restricted to the epithelium can initiate intestinal inflammation in the presence of normal underlying immunity has refocused attention on epithelial dysfunction in IBD. We review the components of the secreted and cellular barrier, their regulation, including interactions with underlying innate and adaptive immunity, evidence from animal models of the barrier's role in preventing intestinal inflammation, and evidence of barrier dysfunction in both Crohn's disease and ulcerative colitis.

Intestinal trefoil factor/TFF3 promotes re-epithelialization of corneal wounds

Disorders of wound healing characterized by impaired or delayed re-epithelialization are a serious medical problem. These conditions affect many tissues, are painful, and are difficult to treat. In this study using cornea as a model, we demonstrate the importance of trefoil factor 3 (TFF3, also known as intestinal trefoil factor) in re-epithelialization of wounds. In two different models of corneal wound healing, alkali- and laser-induced corneal wounding, we analyzed the wound healing process in in vivo as well as in combined in vivo/in vitro model in wild type (Tff3(+)(/)(+)) and Tff3-deficient (Tff3(-)(/)(-)) mice. Furthermore, we topically applied different concentrations of recombinant human TFF3 (rTFF3) peptide on the wounded cornea to determine the efficacy of rTFF3 on corneal wound healing. We found that Tff3 peptide is not expressed in intact corneal epithelium, but its expression is extensively up-regulated after epithelial injury. Re-epithelialization of corneal wounds in Tff3(-/-) mice is significantly prolonged in comparison to Tff3(+/+) mice. In addition, exogenous application of rTFF3 to the alkali-induced corneal wounds accelerates significantly in in vivo and in combined in vivo/in vitro model wound healing in Tff3(+/+) and Tff3(-/-) mice. These findings reveal a pivotal role for Tff3 in corneal wound healing mechanism and have broad implications for developing novel therapeutic strategies for treating nonhealing wounds.

Expression of trefoil factor family members correlates with patient prognosis and neoangiogenesis

PURPOSE

Trefoil factor family (TFF) peptides are thought to contribute to epithelial protection and restitution by virtue of their protease-resistant nature and their strong affinity for mucins. However, they are often overexpressed in tumors, where they seem to be negative prognostic factors, possibly contributing to tumor spread, although the precise mechanisms have not been defined.

EXPERIMENTAL DESIGN

Tissue sections from 111 patients with curatively resected advanced gastric carcinoma were immunohistochemically stained for TFF2, ITF (TFF3), and CD34. Microvessel density was expressed as number and area of microvessels. Results were correlated with clinicopathological characteristics and patient survival.

RESULTS

Forty-nine (44.1%) and 41 (36.9%) tumors were immunohistochemically positive for TFF3 and TFF2, respectively. Among the various clinicopathologic variables, overexpression of TFF3 had a significant correlation with patient age only. In addition, a significantly higher prevalence of positive TFF2 staining was detected in large, diffuse tumors and in tumors with lymph node metastasis. The number of microvessels had a significant correlation with both TFF3 and TFF2 staining, whereas the area of microvessels had a significant correlation only with TFF3 staining. Both TFF3 and TFF2 were independent predictors of a worse disease-free survival. TFF3 had a gender-specific negative survival advantage, with a 91.3% disease-free survival in female patients with TFF3-negative advanced gastric carcinoma.

CONCLUSIONS

Induction of increased tumor vascularity might be one of the mechanisms by which TFFs confer metastatic phenotype and frequent disease recurrence in gastric carcinomas. Female patients with TFF3-negative advanced gastric carcinoma have comparable survival as that reported for patients with early gastric carcinoma.

Intestinal trefoil factor promotes invasion in non-tumorigenic Rat-2 fibroblast cell

Intestinal trefoil factor (TFF3) is essential in regulating cell migration and maintaining mucosal integrity in gastrointestinal tract. We previously showed that TFF3 was overexpressed in gastric carcinoma. Whether TFF3 possesses malignant potential is not fully elucidated. We sought to investigate the effects of inducting TFF3 expression in a non-malignant rat fibroblast cell line (Rat-2) on the cell proliferation, invasion and the genes regulating cell invasion. Invasiveness and proliferation of transfected Rat-2 cell line were assessed using in vitro invasion chamber assay and colorimetric MTS assay. Differential mRNA expressions of invasion-related genes, namely, metalloproteinases (MMP-9), tissue inhibitors of metalloproteinases (TIMP-1), beta-catenin and E-cadherin, were determined by quantitative real-time polymerase chain reaction (PCR). We showed that TFF3 did not inhibit the proliferation of Rat-2 cells. We also demonstrated that transfection of TFF3 significantly promoted invasion of Rat-2 cells by 1.4- to 2.2-folds. There was an upregulation of beta-catenin (13.1-23.0%) and MMP-9 (43.4-92.2%) mRNA expression levels, and downregulation of E-cadherin (25.6-33.8%) and TIMP-1 (31.5-37.8%) in TFF3-transfected cells compared to controls during 48-h incubation. Our results suggested that TFF3 possesses malignant potential through promotion of cell invasiveness and alteration of invasion-related genes.

Trefoil factor family (TFF) peptides of normal human Vater's ampulla

Vater's ampulla is of great clinical relevance with regard to the influx of chyme, ascending inflammation, intubation during diagnostic and therapeutic endoscopic maneuvers, therapeutic papillotomy and, especially, the formation of malignancies. Little is known about the distribution of trefoil factor family (TFF) peptides in the ampulla. We have therefore examined TFF peptide distribution in the normal ampulla of Vater and compared it with that in duodenal mucosa and Brunner's glands. Expression and synthesis of TFF peptides in Vater's ampulla and duodenum was investigated by reverse transcription-polymerase chain reaction, Western blot and immunohistochemistry. The samples studied originated from 30 autopsy cases with short postmortem intervals. TFF3 was expressed in the ampulla of Vater. mRNA expression of TFF1 was detected in only approximately 25% of the investigated samples. Western blot revealed the production of TFF3 and immunohistochemistry showed that TFF3 was the product of goblet cells. TFF peptide composition of Vater's ampulla varied in comparison with that in the duodenum regarding TFF2 expression. The ampulla of Vater thus has a unique profile of TFF peptide production, supporting the hypothesis that the ampulla is an autonomous organ. The observed differences in the TFF peptide distribution between the duodenum and Vater's ampulla favour the investigation of TFF peptides as prognostic markers in the classification of ampullary carcinomas.

Anti-sense trefoil factor family-3 (intestinal trefoil factor) inhibits cell growth and induces chemosensitivity to adriamycin in human gastric cancer cells

Intestinal trefoil factor (ITF), which is normally absent in gastric mucosa, is over-expressed in gastric cancer. However, the functional significance of ITF in gastric cancer is unknown. We examined the effects of blocking ITF expression on the growth of gastric cancer cells and their responses to chemotherapeutic agents. Anti-sense ITF cDNA was cloned into mammalian expression vector pcDNA3 and was transfected into an ITF-expressing gastric cancer cell line SNU-1. We assessed the doubling time and anchorage dependent growth of the transfected cells using growth curve and soft agar assay respectively. Cell cycle analysis and apoptosis were determined by flow cytometry and cell death ELISA. The response to chemotherapeutic agents after transfecting anti-sense ITF was also examined. Anti-sense ITF transfectant (3A-5) had a significantly longer doubling time as compared to control cells which were transfected with empty vector (32.4 hr vs 26.9 hr, p < 0.05). In the soft agar assay, 3A-5 formed fewer colonies than control (3.5 colonies vs 23.5 colonies, p < 0.05). Although there was no significant difference in the cell cycle distribution between 3A-5 and control, anti-sense ITF resulted in marked increase in adriamycin-induced apoptosis. Our results demonstrated that blocking the expression of ITF inhibits growth of gastric cancer cells and enhances the response to chemotherapy.

Distribution of TFF peptides in corneal disease and pterygium

The central cornea of 10 cadavers and 33 patients suffering from keratoconus, herpetic keratitis, Fuchs' dystrophy and pterygium were analysed focusing on the expression of TFF peptides by means of reverse transcription polymerase chain reaction and immunohistochemistry. TFF1 and TFF3 transcripts were detected in healthy corneae as well as in pterygia. Only TFF3 mRNA was transcribed in keratoconus, Fuchs' dystrophy and herpetic keratitis. Immunohistochemistry revealed absence of all three TFF peptides in healthy corneae but production of TFF3 in each of the diseased corneae. In pterygia both TFF1 and TFF3 synthesis was detectable in goblet cells. The absence of TFF peptide production in the healthy cornea indicates that TFF3 secretion is induced in different corneal diseases by yet unknown stimuli. Here TFF3 synthesis can be interpreted as a protection mechanism, because all corneal diseases analysed are characterized by progressive tissue destruction. TFF1 and TFF3 production by goblet cells in pterygia is comparable to the healthy conjunctiva suggesting that TFF peptides do not play a significant role in the pathogenesis of pterygia.

Trefoil factor family (TFF) peptides and cancer progression

TFF peptides are involved in mucosal maintenance and repair through motogenic and antiapoptotic activities. These peptides are overexpressed during inflammatory processes and cancer progression. They also function as scatter factors, proinvasive and angiogenic agents. Such a divergence is related to the pathophysiological state of tissues submitted to persistent aggressive situations during digestive processes in the normal gastrointestinal tract, inflammatory and neoplastic diseases. In agreement with this model, TFF peptides are connected with multiple oncogenic pathways. As a consequence, the TFF signaling pathways may serve as potential targets in the control of chronic inflammation and progression of human solid tumors.

Trefoil factors: initiators of mucosal healing

Maintaining the integrity of the gastrointestinal tract, despite the continual presence of microbial flora and injurious agents, is essential. Epithelial continuity depends on a family of small, yet abundant, secreted proteins--the trefoil factors (TFFs). TFFs protect mucous epithelia from a range of insults and contribute to mucosal repair, although the signalling events that mediate these responses are only partially understood.

Preventive effect of hydrotalcite on gastric mucosal injury in rats induced by taurocholate

AIM: To study the preventive effect of hydrotalcite on gastric mucosal injury in rat induced by taurocholate, and to investigate the relationship between the protective mechanism of hydrotalcite and the expression of trefoil factor family 2 (TFF2) mRNA and c-fos protein.

METHODS: Forty five male Wistar rats were randomly divided into hydrotalcite group, ranitidine group and control group. Gastric mucosal injury was induced by introgastric acidified taurocholate. OD value of TFF2 mRNA expression in gastric mucous cells was determined by hybridization and computer image analysis system. OD value of c-fos protein expression in gastric mucous cells was measured by immunohistochemistry and computer image analysis system.

RESULTS: The gross mucosal injury index in hydrotalcite group was significantly lower than that in ranitidine group and control group (8.60 ± 2.20 vs 16.32 ± 4.27, 29.53 ± 5.39; P < 0.05, P < 0.01). The expression level of TFF2 mRNA in hydrotalcite group was markedly higher than that in ranitidine group and control group (0.56 ± 0.09 vs 0.30 ± 0.05, 0.28 ± 0.03, P < 0.05). The OD value of c-fos protein in hydrotalcite group was higher than that in ranitidine group and control group (0.52 ± 0.07 vs 0.31 ± 0.04, 0.32 ± 0.05, P < 0.05).

CONCLUSION: Hydrotalcite can protect gastric mucosal injury in rats induced by taurocholate, which may be related to the increased expression of TFF2 and c-fos protein.

Age-related trends in gene expression in the chemosensory-nasal mucosae of senescence-accelerated mice

We have utilized high-density GeneChip oligonucleotide arrays to investigate the use of the senescence-accelerated mouse (SAM) as a biogerontological resource to identify patterns of gene expression in the chemosensory-nasal mucosa. Gene profiling in chronologically young and old mice of the senescence-resistant (SAMR) and senescence-prone (SAMP) strains revealed 133 known genes that were modulated by a three-fold or greater change either in one strain or the other or in both strains during aging. We also identified known genes in our study which based on their encoded proteins were identified as aging-related genes in the aging neocortex and cerebellum of mice as reported by Lee et al. (2000) [Nat. Genet. 25 (2000) 294]. Changes in gene profiles for chemosensory-related genes including olfactory and vomeronasal receptors, sensory transduction-associated proteins, and odor and pheromone transport molecules in the young SAMR and SAMP were compared with age-matched C57BL/6J mice. An analysis of known gene expression profiles suggests that changes in the expression of immune factor genes and genes associated with cell cycle progression and cell death were particularly prominent in the old SAM strains. A preliminary cellular validation study supported the dysregulation of cell cycle-related genes in the old SAM strains. The results of our initial study indicated that the use of the SAM models of aging could provide substantive information leading to a more fundamental understanding of the aging process in the chemosensory-nasal mucosa at the genomic, molecular, and cellular levels.

Cell type specific expression of secretory TFF peptides: colocalization with mucins and synthesis in the brain

The "TFF domain" is an ancient cysteine-rich shuffled module forming the basic unit for the family of secretory TFF peptides (formerly P-domain peptides and trefoil factors). It is also an integral component of mosaic proteins associated with mucous surfaces. Three mammalian TFF peptides are known (i.e., TFF1-TFF3); however, in Xenopus laevis the pattern is more complex (xP1, xP4.1, xP4.2, and xP2). TFF peptides are typical secretory products of a variety of mucin-producing epithelial cells (e.g., the conjunctiva, the salivary glands, the gastrointestinal tract, the respiratory tract, and the uterus). Each TFF peptide shows an unique expression pattern and different mucin-producing cells are characterized by their specific TFF peptide/secretory mucin combinations. TFF peptides have a pivotal role in maintaining the surface integrity of mucous epithelia in vivo. They are typical constituents of mucus gels, they modulate rapid mucosal repair ("restitution") by their motogenic and their cell scattering activity, they have antiapoptotic effects, and they probably modulate inflammatory processes. Pathological expression of TFF peptides occurs as a result of chronic inflammatory diseases or certain tumors. TFF peptides are also found in the central nervous system, at least in mammals. In particular, TFF3 is synthesized from oxytocinergic neurons of the hypothalamus and is released from the posterior pituitary into the bloodstream.

TGF-β1-induced PAI-1 gene expression requires MEK activity and cell-to-substrate adhesion

The type-1 inhibitor of plasminogen activator (PAI-1) is an important physiological regulator of extracellular matrix (ECM) homeostasis and cell motility. Various growth factors mediate temporal changes in the expression and/or focalization of PAI-1 and its protease target PAs, thereby influencing cell migration by barrier proteolysis and/or ECM adhesion modulation. TGF-β1, in particular, is an effective inducer of matrix deposition/turnover, cell locomotion and PAI-1 expression. Therefore, the relationship between motility and PAI-1 induction was assessed in TGF-β1-sensitive T2 renal epithelial cells. PAI-1 synthesis and its matrix deposition in response to TGF-β1 correlated with a significant increase in cell motility. PAI-1 expression was an important aspect in cellular movement as PAI-1-deficient cells had significantly impaired basal locomotion and were unresponsive to TGF-β1. However, the induced migratory response to this growth factor was complex. TGF-β1 concentrations of 1-2 ng/ml were significantly promigratory, whereas lower levels (0.2-0.6 ng/ml) were ineffective and final concentrations ≥5 ng/ml inhibited T2 cell motility. This same growth factor range progressively increased PAI-1 transcript levels in T2 cells consistent with a bifunctional role for PAI-1 in cell migration. TGF-β1 induced PAI-1 mRNA transcripts in quiescent T2 cells via an immediate-early response mechanism. Full TGF-β1-stimulated expression required tyrosine kinase activity and involved MAPK/ERK kinase (MEK). MEK appeared to be a major mediator of TGF-β1-dependent PAI-1 expression and T2 cell motility since PD98059 effectively attenuated both TGF-β1-induced ERK1/2 activation and PAI-1 transcription as well as basal and growth factor-stimulated planar migration. Since MEK activation in response to growth factors is adhesion-dependent, it was important to determine whether cellular adhesive state influenced TGF-β1-mediated PAI-1 expression in the T2 cell system. Cells maintained in suspension culture (i.e., over agarose underlays) in growth factor-free medium or treated with TGF-β1 in suspension expressed relatively low levels of PAI-1 transcripts compared with the significant induction of PAI-1 mRNA evident in T2 cells upon stimulation with TGF-β1 during adhesion to a fibronectin-coated substrate. Attachment to fibronectin alone (i.e., in the absence of added growth factor) was sufficient to initiate PAI-1 transcription, albeit at levels considerably lower than that induced by the combination of cell adhesion in the presence of TGF-β1. T2 cells allowed to attach to vitronectin-coated surfaces also expressed PAI-1 transcripts but to a significantly reduced extent relative to cells adherent to fibronectin. Moreover, newly vitronectin-attached cells did not exhibit a PAI-1 inductive response to TGF-β1, at least during the short 2 hour period of combined treatment. PAI-1 mRNA synthesis in response to substrate attachment, like TGF-β1-mediated induction in adherent cultures, also required MEK activity as fibronectin-stimulated PAI-1 expression was effectively attenuated by the MEK inhibitor PD98059. These data indicate that cellular adhesive state modulates TGF-β1 signaling to particular target genes (i.e., PAI-1) and that MEK is a critical mediator of the PAI-1+/promigratory phenotype switch induced by TGF-β1 in T2 cells.