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Biomedical subjects

H Prentice

Publications and source records attributed to H Prentice.

24 records · Page 2Linked to original sources
PubMed1992

The human skeletal alpha-actin gene is regulated by a muscle-specific enhancer that binds three nuclear factors.

The tissue-specific distal promoter of the human skeletal alpha-actin gene (-1282 to -708) induces transcription in myogenic cells approximately 10-fold and, with the most proximal promoter domain (-153 to -87), it synergistically increases transcription 100-fold (Muscat and Kedes 1987). We report here that it is a short fragment of the distal promoter, the distal regulatory element (DRE) from -1282 to -1177 that functions as a muscle-specific, composite enhancer. An internal deletion in the DRE (delta -1282/-1151) in the context of the full-length 2000 bp promoter, resulted in a 10-fold reduction in transcription. Three distinct nuclear proteins, DRF-1, DRF-2, and DRF-3, interact specifically with the DRE between positions -1260 and -1193. A site specific mutation that abolishes DRF-2 binding also results in a 10-fold reduction in transcriptional activity. The DRF-2 nuclear protein has characteristics similar to those of the muscle-specific regulatory factor, MEF-2 (Buskin and Hauschka 1989; Gossett et al., 1989). Like the MEF-2 binding site in the muscle creatine kinase enhancer, the critical DRF-2 binding site is also an A/T-rich sequence element. The DRF-2 nuclear protein binds equally well to the MCK MEF-2 binding site and to the A/T-rich regulatory element of the skeletal muscle fast-twitch troponin C gene (Gahlmann and Kedes 1990). Furthermore, this troponin C site competes in vivo for DRF-2 driven expression of the skeletal alpha-actin gene in C2 cells. The DRF-2 site alone, however, does not activate transcription in muscle cells when linked to the SV40 promoter. We conclude that the DRF-2 binding element is a MEF-2 binding site that is required but insufficient for regulation of muscle-specific skeletal alpha-actin gene expression by the DRE. Thus, muscle-specific regulation of the human skeletal alpha-actin gene appears to require interactions between the other elements of the composite DRE enhancer with the protein:DNA complex formed by DRF-2.

Actins↗
PubMed1987

Multiple basal elements of a human hsp70 promoter function differently in human and rodent cell lines.

The human heat shock protein 70 (hsp70) gene is expressed constitutively in a wide variety of cells. Two separate promoter domains determine this basal level of hsp70 expression. The proximal domain is contained within 84 bases of the transcription initiation site and consists of three elements which appear to interact with the TATA factor(s) and CCAAT-box-binding transcription factor and SP1, respectively. The proximal domain is sufficient for near-maximal basal expression to rodent cell lines. The distal promoter domain consists of sequences upstream of -84 and is necessary in conjunction with the proximal domain for full basal expression in human cell lines. Although in BALB/c 3T3 cells the distal promoter domain plays little role in basal expression, it is functional as evidenced by the ability to compensate efficiently for mutations in the proximal CCAATC homology. The distal domain does not compensate as efficiently for proximal-domain mutations in HeLa cells. Basal expression of this human hsp70 promoter is, therefore, determined by multiple elements. Fewer elements are required for basal expression in rodent cell lines than in human cell lines, suggesting that there are significant differences between the rodent and human transcription apparatuses.

Animals↗
PubMed1986

Nerve growth factor activates Thy-1 and neurofilament gene transcription in rat PC12 cells.

The effect of nerve growth factor (NGF) on the expression of neurofilament and Thy-1 genes in rat PC12 pheochromocytoma cells was examined at both the transcriptional and post-transcriptional levels. Addition of NGF to cultured PC12 cells produced increases in mRNAs corresponding to the 68 kd neurofilament protein (NF68) and the Thy-1 glycoprotein within 24 h, with maximal effects of some 90- and 45-fold stimulation (relative to beta-actin mRNA) being observed after 12 and 4 days of treatment, respectively. In addition, transcriptional run-off analyses using isolated nuclei showed that NGF treatment resulted directly in 8- and 4-fold increases in the rate of NF68 and Thy-1 gene transcription. These gene activation events were independent of overt morphological differentiation of PC12 cells occurring both under conditions permissive and non-permissive for neurite outgrowth, and once established the new molecular phenotype was dependent upon the continued presence of NGF. This is the first molecular evidence for the reversible activation of neuron-specific genes during NGF-induced differentiation in PC12 cells.

Journal Article↗
PubMed1985

Gene organization of DC and DX subregions of the human major histocompatibility complex.

The DC and DX subregions of the human major histocompatibility complex (MHC) have been cloned from a cosmid library made from a human B-cell line, Priess. The DC subregion, 48 kilobases, includes the DC alpha and DC beta genes. A second DC-like region, the DX subregion, 35 kilobases, contains the DX alpha gene and a newly found beta gene termed DX beta. Since the DC and DX genes are highly homologous in nucleotide sequence, gene size, exon-intron organization, and direction of transcription, the DC and DX subregions were presumably generated by duplication of an ancestral alpha-beta gene pair. Nucleotide sequencing indicates that all four genes have intact coding sequences and promoter regions. Homology between the upstream promoter sequences of these four genes and seven other class II genes at nucleotides -69 to -78 and -98 to -110 highlights these previously described conserved elements. Moreover, a striking conservation of flanking alpha-gene-specific and beta-gene-specific sequences has been observed. Comparison of Southern blots of Priess DNA with DC alpha and DC beta cDNA probes with isolated cosmid clones showed that (i) the human chromosome encodes only two DC alpha-related and two DC beta-related genes, namely, DC alpha, DX alpha, DC beta, and DX beta, and (ii) the DC and DX subregions are homozygous in Priess cells.

Chromosome Mapping↗