An ultra-high sulfur keratin gene is expressed specifically during hair growth.

To study the regulation of the hair cycle in the mouse, we have isolated and characterized a gene for ultra high sulfur keratin that is expressed specifically during the active hair growth cycle. The gene (gUHSK-704Eco) was isolated as a member of a gene cluster on a recombinant phage with a DNA insert of 18 kb that was isolated by screening a murine genomic library at low stringency with a synthetic oligonucleotide derived from a sheep high sulfur keratin gene (Powell, Nucleic Acids Res. 1983 11, 5327). The murine ultra-high sulfur keratin gene has no intervening sequence; the 558 nucleotide of the coding region specify 186 amino acids, of which 70 (37%) are cysteine. A Cys-Cys-Gln-Pro repeat is found 12 times within the coding region. RNA dot blots show that the ultra-high sulfur keratin gene is expressed during the hair cycle concomitant with the anterior-posterior temporal pattern of the normal murine hair cycle.

Characterization of the promoter region of the human thrombospondin gene. DNA sequences within the first intron increase transcription.

Thrombospondin (TSP) is an extracellular matrix glycoprotein whose synthesis and secretion by mesenchymal cells is regulated at the level of gene transcription by platelet-derived growth factor. To examine the transcriptional regulation of the TSP gene at the molecular level, a genomic clone containing the human TSP promoter and flanking sequence was isolated and characterized. A 3.8-kilobase pair (kb) DNA fragment containing the first three exons, the first two introns, and 2.2 kb of 5'-flanking region was sequenced, and the site of transcription initiation was determined by both primer extension and S1 nuclease mapping. Consensus sequences for several potential regulatory elements were found in the 5'-flanking sequence, including a TATA box consensus sequence, TTTAAAA, located 24 base pairs upstream from the transcription start site. A chimeric gene was constructed containing the first intron, the first exon, and 2.0 kb of 5'-flanking sequence of the TSP gene fused to the promoterless gene for chloramphenicol acetyltransferase. When transfected into COS-1 or NIH3T3 cells this gene construct was transcribed, indicating the presence of a functional promoter in the TSP sequence. Transient transfection studies using deletion mutants of this TSP-chloramphenicol acetyltransferase construct were performed to locate cis-acting regulatory sequences. The deletion of flanking sequence 5' to position -234 had little or no effect on transcriptional activity, whereas deletion of 5'-flanking sequence extending further in the 3' direction resulted in the gradual loss of transcriptional activity. The removal of the first intron resulted in a 4-fold decrease in transcript levels, indicating the presence of a cis-acting positive element(s) in the first intron of the human TSP gene. This element(s) was further localized to the region between position +576 and position +727.

Deletions in vaccine strains of pseudorabies virus and their effect on synthesis of glycoprotein gp63.

The pseudorabies virus vaccine strains Norden and Bartha each have been reported to have deletions in the small unique component of the genome (B. Lomniczi, M. L. Blankenship, and T. Ben-Porat, J. Virol. 49:970-979, 1984). The deletion in Norden was shown to delete the entire coding region for gI but not any of the coding sequences for gp63. However, gp63 in Norden-infected cells was only 36 kilodaltons, and a 44-kilodalton form of gp63 was released into the medium. In Bartha, the deletion removed the coding region for all but 89 amino acids of gp63, and no gp63 was detected in either Bartha-infected cells or medium.

The eukaryotic translation initiation factor 4E is not modified during the course of vaccinia virus replication.

The ability of vaccinia virus to inhibit processes of cap-dependent translational initiation by inactivating the eukaryotic translation initiation factor 4E (eIF-4E) has been examined. Analyses of the quantities of eIF-4E present in either uninfected mouse L929 cells or vaccinia virus-infected cells showed that during the first 12 hr of virus replication, when there is a marked decrease in host gene expression in infected cells, there is no change in the total amount of eIF-4E present. Analyses of eIF-4E that was metabolically labeled with [32P] and then purified by affinity chromatography using m7GTP-Sepharose 4B, indicated that neither the incorporation of radiolabel into eIF-4E nor the amounts of eIF-4E capable of binding to cap structures changed significantly during virus replication. Immunodetection of phosphorylated and unphosphorylated eIF-4E in cell lysates fractionated by two-dimensional gel electrophoresis showed that the steady-state levels of phosphorylated and unphosphorylated forms of eIF-4E were similar in uninfected and virus-infected cells. These results suggest that vaccinia virus does not gain preferential translation of viral mRNAs over other mRNAs in the cell by reducing either eIF-4E phosphorylation or its ability to bind to the cap structure.