Membrane-type 1 matrix metalloproteinase-mediated progelatinase A activation in non-tumorigenic and tumorigenic humaneratinocytes

Elevated expression of type IV collagenases (MMP-2 and MMP-9) has been strongly correlated with tumour progression and metastasis in various tumours. Here, we analysed expression and activation of these MMPs in non-tumourigenic HaCaT cells and the malignant HaCaT variant II-4 rt. In monolayer cultures, both cell types secreted latent MMP-2 (proMMP-2) in comparable amounts, while MMP-9 production was clearly higher in II-4 rt cells. Upon contact with fibrillar collagen type I the malignant II-4 rt cells, but not the HaCaT cells, gained the capability to activate proMMP-2. This process is shown to be membrane-associated and mediated by MT1-MMP. Surprisingly, all membrane preparations from either HaCaT cells or II-4 rt cells grown as monolayers, as well as within collagen gels, contained considerable amounts of active MT1-MMP. However, within collagen gels HaCaT cells showed significantly higher TIMP-2 levels compared to II-4 rt cells. This indicates that TIMP-2 might play a central role for MT1-MMP-mediated gelatinolytic activity. Indeed, collagen type I-induced MT1-MMP-mediated proMMP-2 activation by II-4 rt membranes could be completely abolished by an excess of TIMP-2. In conclusion, our data suggest that MT1-MMP-mediated proMMP-2 activation might be associated with malignant progression of epidermal tumour cells. © 2000 Cancer Research Campaig

T2D: Generating Dialogues Between Virtual Agents Automatically from Text

The Text2Dialogue (T2D) system that we are developing allows digital content creators to generate attractive multi-modal dialogues presented by two virtual agents–by simply providing textual information as input. We use Rhetorical Structure Theory (RST) to decompose text into segments and to identify rhetorical discourse relations between them. These are then 'acted out' by two 3D agents using synthetic speech and appropriate conversational gestures. In this paper, we present version 1.0 of the T2D system and focus on the novel technique that it uses for mapping rhetorical relations to question–answer pairs, thus transforming (monological) text into a form that supports dialogues between virtual agents

Tetanus toxin entry. Nidogens are therapeutic targets for the prevention of tetanus.

Tetanus neurotoxin (TeNT) is among the most poisonous substances on Earth and a major cause of neonatal death in nonvaccinated areas. TeNT targets the neuromuscular junction (NMJ) with high affinity, yet the nature of the TeNT receptor complex remains unknown. Here, we show that the presence of nidogens (also known as entactins) at the NMJ is the main determinant for TeNT binding. Inhibition of the TeNT-nidogen interaction by using small nidogen-derived peptides or genetic ablation of nidogens prevented the binding of TeNT to neurons and protected mice from TeNT-induced spastic paralysis. Our findings demonstrate the direct involvement of an extracellular matrix protein as a receptor for TeNT at the NMJ, paving the way for the development of therapeutics for the prevention of tetanus by targeting this protein-protein interaction

Epidermal Transglutaminase (TGase 3) Is Required for Proper Hair Development, but Not the Formation of the Epidermal Barrier

Transglutaminases (TGase), a family of cross-linking enzymes present in most cell types, are important in events as diverse as cell-signaling and matrix stabilization. Transglutaminase 1 is crucial in developing the epidermal barrier, however the skin also contains other family members, in particular TGase 3. This isoform is highly expressed in the cornified layer, where it is believed to stabilize the epidermis and its reduction is implicated in psoriasis. To understand the importance of TGase 3 in vivo we have generated and analyzed mice lacking this protein. Surprisingly, these animals display no obvious defect in skin development, no overt changes in barrier function or ability to heal wounds. In contrast, hair lacking TGase 3 is thinner, has major alterations in the cuticle cells and hair protein cross-linking is markedly decreased. Apparently, while TGase 3 is of unique functional importance in hair, in the epidermis loss of TGase 3 can be compensated for by other family members

Analysis of skin of nidogen deficient mouse models

Basement membranes (BMs) are produced by complex interactions of laminins, collagen IV, perlecan and nidogen. Nidogen represents a small family of related proteins with two mammalian isoforms nidogen 1 and 2. Nidogens are ubiquitous BM components that have been proposed to play a key role for BM assembly. However, neither nidogen 1 nor nidogen 2 deficient mice showed BM defects suggesting overlapping functions of the two isoforms for the formation of BMs. Nidogen double null mice showed that this is indeed 1the case. These mice die shortly after birth showing various abnormalities particularly in the lung, heart and limb, directly related to BM defects. However, despite the fact that both nidogens are found in all BMs, some BMs in these mice appeared ultrastructurally normal. Mice lacking the high affinity binding site on the laminin g1 chain that is present in most laminin isoforms showed strikingly different phenotypes. While changes in the lung are common, these mice do not display cardiac changes and show a highly penetrant renal aplasia not seen in nidogen double null mice. We were therefore interested to analyse the skin phenotype in these mice in comparison to the nidogen double null mice to understand the biological contribution of the laminin nidogen interactions for nidogen function in skin development. Detailed analysis of the skin BMs revealed different phenotypes between the two mouse strains indicating differences in the role of nidogens and the laminin nidogen interaction for skin physiology

Sequence and regulatory responses of a ribosomal protein gene from the fission yeast Schizosaccharomyces pombe.

We have determined the nucleotide sequence and mapped the 5' and 3' termini of a ribosomal protein gene. The gene is transcribed into a RNA molecule of about 770 nt and appears to initiate at multiple sites, as judged by SI nuclease analysis. Gene dosage experiments with a plasmid born gene leads to a proportional increase of the messenger RNA, but not to an overproduction of the protein, suggesting a posttranscriptional control mechanism. However, the heat shock response of this gene indicates that there is also a potential for transcriptional control. Comparison of the 5' flanking region of this gene with the ribosomal protein gene S 6 from Schizosaccharomyces pombe and with ribosomal protein genes from Saccharomyces cerevisiae revealed homologous sequences, which may be involved in the regulation of ribosomal protein genes