Eukaryotic activator proteins (activators) stimulate transcription by increasing assembly of the preinitiation complex. We have developed methods to quantify the stable assembly of general transcription factors into transcriptional complexes in response to activators. We show that activators function during at least two stages of preinitiation complex assembly: first, to recruit the general transcription factor TFIIB, and then at a second step, after TFIIB entry. It is at this second step that the TATA-box binding protein associated factors act. This step also seems to be critical for activators to stimulate transcription synergistically.

Conclusion. ESE-1 is expressed in synovial tissues in RA and, to a variable extent, in OA, and is specifically induced in synovial fibroblasts, chondroDr. Libermann

Type II collagen, encoded by the COL2A1 gene, is the major collagen of the extracellular matrix of mature articular cartilage. Together with the other cartilage-specific type IX and XI collagens, the highly cross-linked fibrils of triple helical type II collagen molecules form a fibrillar network that confers tensile strength to articular surfaces (1). Chondrocytes comprise the single cellular component of adult hyaline cartilage and are responsive to a number of growth factors and cytokines that either stimulate or inhibit type II collagen synthesis (2). Interleukin-1 (IL-1)

In the early Caenorhabditis elegans embryo, maternally expressed PIE-1 protein is required in germ-line blastomeres to inhibit somatic differentiation, maintain an absence of mRNA transcription, and block phosphorylation of the RNA polymerase II large subunit (Pol II) carboxy-terminal domain (CTD). We have determined that PIE-1 can function as a transcriptional repressor in cell culture assays. By fusing PIE-1 sequences to the yeast GAL4 DNA-binding domain, we have identified a PIE-1 repression domain that appears to inhibit the transcriptional machinery directly. A sequence element that is required for this repressor activity is similar to the Pol II CTD heptapeptide repeat, suggesting that the PIE-1 repression domain might target a protein complex that can bind the CTD. An alteration of this sequence element that blocks repression also impairs the ability of a transgene to rescue a pie-1 mutation, suggesting that this repressor activity may be important for PIE-1 function in vivo.