Mithramycin selectively inhibits collagen-alpha 1(I) gene expression in human fibroblast.

The products of the collagen-alpha 1(I) and -alpha 2(I) genes form the triple helical molecule collagen type I, which constitutes the major ECM protein in tissue fibrosis. The collagen-alpha 1(I) gene is mainly transcriptionally regulated, and its promoter activity depends on the interaction of the transcription factors NF-I and Sp1 with a tandem repeat of evolutionary conserved NF-I/Sp1 switch elements. An increased affinity of Sp1 to these elements has been observed in experimental liver fibrosis. Here, we demonstrate that the DNA binding drug mithramycin displays a high affinity binding to the GC-rich elements in the collagen-alpha 1(I) promoter as measured by DNAse I protection and gel retardation assays. Mithramycin interferes with Sp1 but not with NF-I binding to these sites. At a concentration of 100 nM, mithramycin efficiently reduces basal and TGF-beta-stimulated alpha 1(I) gene expression in human primary fibroblasts. The transcriptional activity and mRNA steady state levels of other genes, including the collagenase gene, as well as the growth rate of fibroblasts remained unchanged on exposure to this drug. Taken together, our results indicate that the transcriptional activity of the type I collagen gene highly depends on its GC-rich regulatory elements, and further, that these elements can be differentially blocked, thereby changing the balance between ECM structural and degrading gene activities in human fibroblasts.

HTLV-I-associated adult T cell leukemia/lymphoma in two patients from Bucharest, Romania.

Two middle-aged patients with T cell lymphoma, both natives of Bucharest, Romania, tested positive for HTLV-I antibodies. Malignant cells had the typical phenotype and morphology of adult T cell leukemia/lymphoma (ATL). Both cases presented with extranodal manifestation, hypercalcemia, early recurrence after initial responses to therapy, and subsequent resistance to conventional and intensified chemotherapy. Infection with HTLV-I was confirmed by PCR analyses of serial biopsies. Neither patient reported known risk factors for HTLV-I infection. This report points to the possibility that Romania may represent an endemic area for HTLV-I and should heighten the awareness towards HTLV-I infections in Romanian patients.

YAC/P1 contigs defining the location of 56 microsatellite markers and several genes across a 3.4-cM interval on mouse chromosome 11.

The characterization of three YAC/P1 contigs from adjacent segments of the central region of mouse Chromosome (Chr) 11 is described. These contigs are based upon 63 YACs and 40 P1 recombinants. From these clones, 185 end sequences were obtained, of which 147 sequences could be converted into sequence-tagged sites and mapped within the three contigs. Deletions were detected in 16 out of 63 YACs; 19 of 63 YACs were found to be chimeric. No such aberrations were found in P1 recombinants. A total of 22 public and 34 newly developed microsatellite markers were unambiguously localized to and ordered in the contigs. In the cryb1/Nf1 interval of the central contig, several new genes have been identified by exon trapping and precisely localized with respect to known STS markers.