Upregulation of the 72-kDa type IV collagenase in epithelial and stromal cells during rat tracheal gland morphogenesis

Developmentally regulated expression of matrix metalloproteinases during fetal rat colon morphogenesis

To investigate the role of matrix metalloproteinases (MMPs) during gastrointestinal tract development, the expression of gelatinases (MMP-2 and MMP-9) was investigated during fetal rat colon morphogenesis. Fetal rat colons were separated into epithelial and mesenchymal fractions without cross contamination using a chelating agent and a dissecting microscope. Gelatinase activity measured using fluorescently labeled gelatin was higher in the mesenchymal than in the epithelial fraction; the developmental profile revealed that, in both fractions, gelatinase activity was enhanced during colon morphogenesis. During colonic gland formation, there was prominent MMP-2 activity, elevated MMP-2 mRNA expression, and an increase in the level of the active form of MMP-2 in the mesenchymal fraction. The mRNA expression of the tissue inhibitor of metalloproteinase 2 corresponded with an elevation in the level of the active form of MMP-2; the mRNA expression of the cell surface activator of MMP-2, membrane type matrix metalloproteinase 1, did not increase significantly. MMP-9 activity was low; only the pro-form was observed in the epithelial fraction at the end of fetal life. These results suggest that, during colon morphogenesis, MMP activity is under strict spatio-temporal control, and that the activity of MMP-2, which is regulated at both the transcriptional and proteolytic activation levels, is very much involved in rat colon morphogenesis.

Characterizing mucous cell remodeling in cystic fibrosis: relationship to neutrophils

RATIONALE

Relatively few studies have characterized mucous cells or mucins in detail in cystic fibrosis (CF), and the relationship between mucous cell abnormalities and neutrophilic inflammation is uncertain.

OBJECTIVES

To characterize mucous cell phenotypes and mucin profiles in CF and to determine if neutrophils accumulate around goblet cells in the epithelium and gland acini in the submucosa.

METHODS

Bronchial biopsies were collected from 7 subjects with CF and 15 control subjects, and the morphology of mucous cells was measured. Immunostains for gel-forming mucins and neutrophil elastase were quantified.

MEASUREMENTS AND MAIN RESULTS

Goblet cell size was increased in CF (p = 0.004), but the number of goblet cells was normal. The volume of submucosal glands was fourfold higher than normal (p = 0.031), but the proportion of mucous and serous cells in CF glands was normal. The patterns of expression of gel-forming mucins in epithelial and submucosal compartments in CF were similar to normal. Although neutrophil elastase immunostaining was intense in the epithelium in CF, neutrophils were largely absent around gland acini in the submucosa.

CONCLUSION

The most prominent pathologic feature in the CF airway is an increase in submucosal gland volume, but serous cell transdifferentiation to mucous cells does not occur, nor are gland acini inflamed with neutrophils. The mechanism for increased submucosal gland volume in CF deserves further study.

Expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases during normal human pulmonary development

AIMS

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are thought to be involved in lung development because they play an important role in the turnover of the extracellular matrix. Although limited data on MMP and TIMP expression are available from animal studies during prenatal pulmonary development, little is known about their expression during human fetal lung development. The aim of this study was to investigate the expression of MMP-1, -2, -9, TIMP-1, -2 and -3 in human fetal lungs from 9 to 42 weeks of gestation.

METHODS AND RESULTS

Forty-five normal human fetal lung samples were analysed by immunohistochemistry. MMP-1, -9, TIMP-1, -2 and -3, but not MMP-2, were expressed in the epithelium at all gestational ages. The endothelium of all vessels and the arterial smooth muscle cells expressed MMP-1, -2, -9, TIMP-2 and -3, but not TIMP-1, at all developmental stages.

CONCLUSION

The extensive distribution of MMPs and TIMPs throughout all stages of human lung development suggests that they play a significant role in the remodelling that occurs in the interstitium and epithelial basement membrane during lung development and in pulmonary vascular development. These data will serve as a base line for comparison with neonatal lung pathology, including pulmonary hypertension.

MMP-2 plays an essential role in producing epithelial-mesenchymal transformations in the avian embryo

To investigate the roles that matrix-degrading proteases may have in development of the chicken embryo, we documented the expression pattern of matrix metalloprotease-2 (MMP-2, 72-kDa type IV collagenase or gelatinase A) and perturbed its function in vitro and in vivo. MMP-2 is expressed as neural crest cells detach from the neural epithelium during an epithelial-mesenchymal transformation (EMT) but is rapidly extinguished as they disperse. It is also expressed in the sclerotome and in the dermis at the time that the EMT is initiated, and also as these cells migrate, and is down-regulated once motility has ceased. These patterns suggest that MMP-2 plays a role in cell motility during the EMT and during later morphogenesis. Inhibitors of MMPs, including BB-94 and TIMP-2 (tissue inhibitor of metalloprotease-2), prevent the EMT that generates neural crest cells, both in tissue culture and in vivo, but do not affect migration of the cells that have already detached from the neural tube. Similarly, knockdown of MMP-2 expression in the dorsal neural tube using antisense morpholino oligos perturbs the EMT, but also does not affect migration of neural crest cells after they have detached from the neural tube. On the other hand, when somites in culture are treated with TIMP-2, some mesenchymal cells are produced, suggesting that they undergo the EMT, but show greatly reduced migration through the collagen gel. MMP-2 is also expressed in mesenchyme where tissue remodeling is in progress, such as in the developing feather germs, in the head mesenchyme, in the lateral plate mesoderm, and in the limb dermis, especially in the regions where tendons are developing. Comparisons of these expression patterns in multiple embryonic tissues suggest a probable role for MMP-2 in the migration phase of the EMT, in addition to mesenchyme dispersion and tissue remodeling. Developmental Dynamics 229:42-53, 2004.

Matrix metalloproteinase-2 from bronchial epithelial cells induces the proliferation of subepithelial fibroblasts

BACKGROUND

In bronchial asthma, subepithelial fibrosis in the conducting airways is associated with increased numbers of subepithelial fibroblasts.

OBJECTIVE

This study examined the hypothesis that MMP-2 from airway epithelial cells induces the proliferation of subepithelial fibroblasts.

METHODS

Using primary bronchial epithelial cells MMP-2, MT1-MMP and TIMP-2 mRNA expression were assessed by Northern blotting and RT-PCR. Primary bronchial epithelial cells transfected with constructs encoding pro-MMP-2 and MT1-MMP (MMP-14).

RESULTS

Transfected cells showed enhanced expression of the appropriate mRNA species by RT-PCR and enhanced MMP-2 or MT1-MMP activity by zymography. Active MMP-2 levels in epithelial supernatants were increased most by cotransfection with pro-MMP-2 and MT1-MMP encoding constructs. By measuring tritiated thymidine incorporation, supernatants from transfected cells were found to enhance DNA synthesis of primary airway fibroblast cultures compared with controls. There was a strong correlation (r = 0.9, P < 0.01) between MMP-2 levels in epithelial cell conditioned media and fibroblast proliferation as indicated by DNA synthesis. The MMP inhibitor 1,10-phenanthroline attenuated the increased proliferation, while the addition of exogenous purified MMP-2 alone also increased fibroblast proliferation.

CONCLUSIONS

Our results support a role for MMP-2 in mediating cross-talk between epithelial cells and myofibroblasts.

Expression of membrane-type 1 matrix metalloproteinase (MT1-MMP) mRNA in trophoblast and endometrial epithelial cell populations of the synepitheliochorial placenta of goats (Capra hircus)

Membrane-type 1 matrix metalloproteinase (MT1-MMP), a membrane-bound matrix metalloproteinase, plays crucial roles in cellular migration through the matrix during embryogenesis, wound healing, and the invasion of host tissues by cancer cells. Mammalian trophoblast cells exhibit different degrees of invasiveness towards the endometrium in different species during gestation. The highly invasive trophoblast cells of primates and rodents which form hemochorial placentae have often been compared to metastatic cancer cells, and are known to express MT1-MMP at their invasive edge. So far, however, little is known about MT1-MMP expression in the placenta of non-invasive type including the synepitheliochorial placenta of bovidae. As an approach to assess the role played by MT1-MMP in the non-invasive synepitheliochorial placentation, we determined the open reading frame (ORF) base sequence of caprine MT1-MMP (DDBJ/EMBL/GenBank database: AB010921); this sequence is the first registered MT1-MMP ORF sequence of artyodactyls which develop placentae of the non-invasive type. The deduced amino acid sequence of caprine MT1-MMP exhibited 92, 87 and 89% identity with its human, mouse and rat counterparts, respectively. Availability of the cloned caprine MT1-MMP cDNA allowed us to carry out Northern blot analysis which revealed that in the placentome, the expression levels of MT1-MMP mRNA were very low on Day 35 of gestation (peri-implantation stage), while the levels gradually increased from Day 75 to Day 100. In the interplacentome regions of the placenta and the uterus, the signal levels were higher than those in the placentome, and increased from Day 35 onward, peaking on Day 75. In situ hybridization experiments revealed that the binucleate trophoblast cells reacted with the MT1-MMP cRNA probe throughout the period examined while the uninuclear principal trophoblast cells did so only on Day 100. Of particular interest is the expression of MT1-MMP transcripts in the luminal and glandular epithelial cells of the gestational endometrium, since epithelial cells in general have been noted to lack MMP expression, including MT-MMPs. The high levels of MT1-MMP expression in the endometrial epithelial cell populations might reflect extensive remodeling during gestation.

Gelatinase A expression in endothelial cells is regulated by at least two cis-acting promoter elements

Increased expression of gelatinase A is associated with both angiogenesis and alterations in blood vessel structure. Heart-derived endothelial cells derived from spontaneously hypertensive rats (SHR) were found to express significantly more gelatinase A in culture, both at the protein and mRNA level, than endothelial cells from normotensive Wistar-Kyoto (WKY) rats. Other matrix metalloproteinases, as well as their tissue inhibitors, were not differentially regulated. A 1683 bp gelatinase A promoter fragment linked to a luciferase reporter demonstrated up to 40-fold more activity when transfected into SHR-derived cells versus WKY-derived cells. The promoter region between -1324 and -1272, previously termed RE1, contributed up to a five-fold increase in basal promoter activity in both cells, but contributed only 12% of the promoter activity in SHR-derived cells compared to 85% in WKY-derived cells. In SHR-derived cells, but not in WKY-derived cells, a second region between -1435 and -1375, termed RE2, contributed 60% of the total activity of the 1683 bp promoter fragment. Both electrophoretic mobility shift assays and Southwestern blots demonstrated differences in RE2-specific binding factors in nuclear extracts derived from the two cell types. SHR-derived endothelial cells thus represent a new model system to study the regulation of gelatinase A expression, which itself may contribute to the abnormal vascular structure seen in the SHR.

Tumor-derived EMMPRIN (extracellular matrix metalloproteinase inducer) stimulates collagenase transcription through MAPK p38

EMMPRIN (extracellular matrix metalloproteinase inducer) stimulates fibroblast metalloproteinases (MMP) 1, 2 and 3 (Kataoka et al. (1993) Cancer Res. 53, 3154-3158). Here we focus on MMP-1, showing that in lung tumors, MMP-1's cognate mRNA is strongly expressed in stromal fibroblasts adjacent to EMMPRIN-expressing tumor cells. In vitro, EMMPRIN upregulates MMP-1 mRNA expression in a concentration-dependent manner, with a peak accumulation at 24 h. The response is genistein-sensitive, suggesting it is dependent on tyrosine kinase activity. Analysis of tyrosine phosphorylation-dependent MAP kinases ERK 1/2, SAPK/JNK, and p38 showed that the activity of p38 but not that of the other 2 kinases was elevated in response to EMMPRIN. That p38 activity was required for EMMPRIN stimulation of MMP-1 was evident from results showing that the p38 inhibitor SB203580 blocked this response. This is the first available information regarding the mechanism by which tumor-associated molecules upregulate MMP synthesis in stromal fibroblasts.

Matrix metalloproteinases MMP2 and MMP9 are produced in early stages of kidney morphogenesis but only MMP9 is required for renal organogenesis in vitro

We analyzed matrix metalloproteinase (MMP) production by 11-d embryonic mouse kidneys and the effects of these enzymes on subsequent renal organogenesis. In vivo, immunolocalization of metalloproteinases by laser scanning confocal microscopy and zymograms of kidney lysates showed that the mesenchyme of embryonic kidneys synthesized both MMP9 and MMP2 enzymes. In vitro, embryonic kidneys also secreted both enzymes when cultured in a medium devoid of hormone, growth factor, and serum for 24 h during which T-shaped branching of the ureter bud appeared. We then evaluated the role of MMP2 and MMP9 in kidney morphogenesis by adding anti-MMP2 or anti-MMP9 IgGs to the culture medium of 11-d kidneys for 24 or 72 h. Although it inhibited activity of the mouse enzyme, anti-MMP2 IgGs had no effect on kidney morphogenesis. In contrast, anti-MMP9 IgGs with enzyme-blocking activity impaired renal morphogenesis, in a concentration-dependent manner, by inhibiting T-shaped branching and further divisions of the ureter bud. This effect was irreversible, still observed after inductive events and reproduced by exogenous tissue inhibitor of metalloproteinase 1 (TIMP1), the natural inhibitor of MMP9. These data provide the first demonstration of MMP9 and MMP2 production in vivo by 11-d embryonic kidneys and further show that MMP9 is required in vitro for branching morphogenesis of the ureter bud.

The role of type IV collagenases in rat bladder development and obstruction

The role of type IV collagenases during rat bladder development and in response to partial bladder outlet obstruction was evaluated. Gelatinase gel zymography was performed on developing rat bladders (gestation d 16 and 19, at birth, 5, 10, 15, 20, 30, and 75 d postnatally), after partial obstruction of the bladder outlet in young adults and after separation of the epithelium from the mesenchyme in young adults. Bladder function was assessed by cystometry in obstructed animals. During development, the 72-kD type-IV collagenase [matrix metalloproteinase (MMP)-2, both latent and activated] was maximally expressed in the fetal period and decreased with age; whereas the 92-kD gelatinase (MMP-9) was not expressed in developing or adult bladders. MMP-2 was localized to the bladder mesenchyme and was undetectable in isolated epithelium. In 46 obstructed rats, there was an 8-fold increase in bladder volume and weight along with smooth muscle hypertrophy (mean smooth muscle cell diameter 7.09 +/- 0.11 microns versus 4.65 +/- 0.05 microns in normal animals, p < 0.001). Obstructed rats had increased quantities of latent and activated MMP-2 and MMP-9 compared with sham-operated and normal controls. These findings suggest that expression and activation of type IV collagenases (MMP-2 and 9) are developmentally regulated and play a role in bladder remodeling during developmental morphogenesis and after partial outlet obstruction.

Cell-matrix interactions in gland development in the lung

The tubulo-acinar glands of the conducting airways participate in lung host defense and the pathogenesis of chronic inflammatory airway disease. Models of gland development may provide clues to mechanisms that promote hypersecretion in diseases such as chronic bronchitis and cystic fibrosis. The developmental anatomy of airway glands was described 30 years ago, but the regulation of gland formation remains a mystery. During the pseudoglandular stage of lung development, poorly differentiated surface epithelial cells grow radially from the lumen and invade the airway submucosa. The basal lamina is remodeled during this process and animal studies indicate a correlation between the expression of the 72-kD gelatinase (MMP-2) and gland morphogenesis. Cell culture models with lung epithelial and mesenchymal elements mimic early gland morphogenesis. Studies using this model have corroborated the involvement of 72-kD gelatinase in the formation of gland-like structures. While the secretion and activation of 72-kD gelatinase is correlated with epithelial matrix invasion, the presence of activated 72-kD gelatinase is not by itself sufficient to permit epithelial matrix invasion. Whether the 72-kD gelatinase participates in a more complex proteolytic cascade or whether appropriate localization of the enzyme is critical to airway epithelial morphogenesis is the focus of ongoing investigation.

Focalized proteolysis: spatial and temporal regulation of extracellular matrix degradation at the cell surface

Cells respond to changes in their microenvironment by altering their cell surface and extracellular matrix proteins. Rapid and irreversible changes in these proteins are possible through their degradation or activation by proteolysis. By focalizing the proteolytic events at or near the cell surface, these processes can be effective even in the presence of high concentrations of inhibitors. Evidence is emerging that secreted and transmembrane matrix metalloproteinases, metalloproteinases of the adamalysin and astacin (tolloid) families, and serine proteinases are crucial in development, differentiation, cell motility and invasion, and cell-extracellular decisions.