We have shown that osteogenic protein-1 (OP-1) (bone morphogenetic protein-7) is responsible for the induction of nephrogenic mesenchyme during embryonic kidney development. Gene knock-out studies showed that OP-1 null mutant mice die of renal failure within the first day of postnatal life. In the present study, we evaluated the effect of recombinant human OP-1 for the treatment of acute renal failure after 60 min bilateral renal artery occlusion in rats. Bioavailability studies in normal rats indicate that ‫ف‬ 1.4 g OP-1/ml is available in the circulation 1 min after intravenous administration of 250 g/kg, which then declines steadily with a half life of 30 min. About 0.5% of the administered OP-1 dose/g tissue is targeted for OP-1 receptors in the kidney. We show that OP-1 preserves kidney function, as determined by reduced blood urea nitrogen and serum creatinine, and increased survival rate when administered 10 min before or 1 or 16 h after ischemia, and then at 24-h intervals up to 72 h after reperfusion.

The SV40 enhancer contains three genetically defined elements, called A, B and C, that can functionally compensate for one another. By using short, synthetic DNA oligonucleotides, we show that each of these elements can act autonomously as an enhancer when present as multiple tandem copies. Analysis of a progressive series of B element oligomers shows a single element is ineffective as an enhancer and that the activity of two or more elements increases with copy number. Assay in five different cell lines of two separate enhancers containing six tandem copies of either the B or C element shows that these elements possess different cell‐specific activities. Parallel oligomer enhancer constructs containing closely spaced double point mutations display no enhancer activity in any of the cell lines tested, indicating that these elements represent single units of enhancer function. These elements contain either a ‘core’ or ‘octamer’ consensus sequence but these consensus sequences alone are not sufficient for enhancer activity. The different cell‐specific activities of the B and C elements are consistent with functional interactions with different trans‐acting factors. We discuss how tandem duplication of such dissimilar elements, as in the wild‐type SV40 72‐bp repeats, can serve to expand the conditions under which an enhancer can function.

A truncated ICP4 peptide which contains the amino-terminal 774 amino acids of the 1,298-amino-acid polypeptide is proficient for DNA binding, autoregulation, and transactivation of some viral genes (N. A. DeLuca and P. A. Schaffer, J. Virol. 62:732-743, 1988) and hence exhibits many of the properties characteristic of intact ICP4. To define the primary sequence important for the activities inherent in the amino-terminal half of the ICP4 molecule, insertional and deletion mutagenesis of the sequences encoding these residues were conducted. The DNA-binding activity of the molecule as assayed by the association with a consensus binding site was sensitive to insertional mutagenesis in two closely linked regions of the molecule. One region between amino acids 445 and 487 is critical for DNA binding and may contain a helix-turn-helix motif. The second region between amino acids 263 and 338 reduces the binding activity to a consensus binding site. When analyzed in the viral background, the DNA-binding activity of a peptide containing an insertion at amino acid 338 to a consensus binding site was reduced while the association with an alternative sequence was eliminated, suggesting a possible mechanism by which ICP4 may recognize a broader range of sequence elements. Mutations which eliminated DNA binding also eliminated or reduced both transactivation and autoregulation, supporting the requirement for DNA binding for these activities. Peptides that retained the deduced DNA-binding domain but lacked amino acids 143 through 210 retained the ability to associate with the consensus site and autoregulatory activity but were deficient for transactivation, demonstrating that the structural requirements for transactivation are greater than those required for autoregulation.

The herpes simplex virus (HSV) type 1 immediate-early regulatory protein ICP4 is required for induced expression of HSV early and late genes, yet the mechanism by which this occurs is not known. We examined the promoter and flanking sequences of the HSV early gene that encodes thymidine kinase for the ability to interact specifically with ICP4 in gel retardation assays. Protein-DNA complexes containing ICP4 were observed with several distinct regions flanking the tk promoter. cis-Acting elements that interact with cellular transcription factors were apparently not required for these interactions to form. Purified ICP4 formed protein-DNA complexes with fragments from these regions, and Southwestern (DNA-protein blot) analysis indicated that the interaction between ICP4 and these sequences can be direct. None of the tk sequences that interact with ICP4 contains a consensus binding site for ICP4 (S. W. Faber and K. W. Wilcox, Nucleic Acids Res. 14:6067-6083, 1986), reflecting the ability of ICP4 to interact with more than one DNA sequence. A mutated ICP4 protein expressed from the viral genome that retains the ability to bind to a consensus binding site but does not bind specifically to the identified sites flanking the tk promoter results in induced transcription of the tk gene. These data support hypotheses for ICP4-mediated transactivation of the tk promoter in Vero cells that do not require the intrinsic ability of ICP4 to bind specifically in or near the promoter of the tk gene.