Genevieve Stapleton

Transcriptional regulation of cell invasion: AP-1 regulation of a multigenic invasion programme

The focus of this review will be on the regulation of the multigenic invasion programme by activator protein-1 (AP-1). Investigation of AP-1-regulated gene expression in transformed cells can be used to identify the genes in the multigenic invasion programme and to validate them as targets for diagnosis or therapy.

Regulation of a multigenic invasion programme by the transcription factor, AP-1: re-expression of a down-regulated gene, TSC-36, inhibits invasion.

The transcription factor AP-1 (activator protein-1) is required for transformation by many oncogenes, which function upstream of it in the growth factor-ras signal transduction pathway. Previously, we proposed that one role of AP-1 in transformation is to regulate the expression of a multigenic invasion programme. As a test of this proposal we sought to identify AP-1 regulated genes based upon their differential expression in 208F rat fibroblasts transformed by FBR-v-fos (FBR), and to determine if they functioned in the invasion programme. Subtracted cDNA libraries specific for up- or down-regulated genes in FBRs compared to 208Fs were constructed and analysed. Northern analysis revealed that the cDNAs in both libraries represented differentially expressed genes. Nucleic acid sequence analysis of randomly selected cDNA clones from each library coupled with searches of nucleic acid and amino acid sequence databases determined that many of the cDNAs represented proteins that function in various aspects of the invasion process. Functional analysis of one the down-regulated genes, TSC-36/follistatin-related protein (TSC-36/Frp), which has not previously been associated with invasion, demonstrated that its expression in FBRs inhibited in vitro invasion. These results support the proposal that AP-1 in transformed cells regulates a multigenic invasion programme.

Combined Extracellular Matrix Cross-linking Activity of the Peroxidase MLT-7 and the Dual Oxidase BLI-3 Is Critical for Post-embryonic Viability in Caenorhabditis elegans

The nematode cuticle is a protective collagenous extracellular matrix that is modified, cross-linked, and processed by a number of key enzymes. This Ecdysozoan-specific structure is synthesized repeatedly and allows growth and development in a linked degradative and biosynthetic process known as molting. A targeted RNA interference screen using a cuticle collagen marker has been employed to identify components of the cuticle biosynthetic pathway. We have characterized an essential peroxidase, MoLT-7 (MLT-7), that is responsible for proper cuticle molting and re-synthesis. MLT-7 is an active, inhibitable peroxidase that is expressed in the cuticle-synthesizing hypodermis coincident with each larval molt. mlt-7 mutants show a range of body morphology defects, most notably molt, dumpy, and early larval stage arrest phenotypes that can all be complemented with a wild type copy of mlt-7. The cuticles of these mutants lacks di-tyrosine cross-links, becomes permeable to dye and accessible to tyrosine iodination, and have aberrant collagen protein expression patterns. Overexpression of MLT-7 causes mutant phenotypes further supporting its proposed enzymatic role. In combination with BLI-3, an H2O2-generating NADPH dual oxidase, MLT-7 is essential for post-embryonic development. Disruption of mlt-7, and particularly bli-3, via RNA interference also causes dramatic changes to the in vivo cross-linking patterns of the cuticle collagens DPY-13 and COL-12. This points toward a functionally cooperative relationship for these two hypodermally expressed proteins that is essential for collagen cross-linking and proper extracellular matrix formation.

Chapter 2.2.3 Brain region-specific genes: the hippocampus

Publisher Summary The chapter discusses four approaches along with their merits and drawbacks, and possible means to the identification of genes and transcripts whose expression is restricted to the hippocampus, and the advantages and drawbacks of the techniques employed. Unexpectedly, each approach highlights a different and non-overlapping subset of genes, but the expression of at least some of these was largely if not exclusively restricted to the hippocampus. The most important method is differential hybridization. This yielded a gene, Cyp7b, whose expression is largely but not exclusively restricted to the hippocampal formation and encoding a novel enzyme metabolizing neurosteroids. The candidate gene family approach yielded a new serine protease, BSP1 with a highly restricted pattern of expression that permits exploitation in a transgenic context, and protein tyrosine phosphatase (PTP) gamma, whose restricted pattern of expression warrants further study.

Beatson International Cancer Conference: invasion and metastasis

While the salient feature of cancer is uncontrolled cell growth proliferation, the most life-threatening form of the disease oc in the latter stages as tumours acquire the ability to invade metastasize to other sites in the organism. During the progre to malignancy, changes in the regulation of motility and inva properties of tumour cells occur, involving changes in respon growth factors and the extracellular matrix (ECM). Onc secondary tumour is established, its new growth and survi dependent on the formation of new blood vessels to the tu (angiogenesis). Importantly, all of these processes occur nor in the organism and so it is their deregulation which results i malignant phenotype. The fourth Beatson International Ca Conference, sponsored by the Cancer Research Campaign a Association for International Cancer Research, provided a s lating forum in which to emphasize the advances in cellular molecular mechanisms controlling the various stages of m tasis, as well as highlighting the advances in potential therap strategies to control these latter stages of cancer.