Wilms' tumour (WT) has a diverse and complex molecular aetiology, with several different loci identified by cytogenetic and molecular analyses. One such locus is on chromosome 7p, where cytogenetic abnormalities and loss of heterozygosity (LOH) indicate the presence of a Wilms' tumour suppressor gene. In order to isolate a candidate gene for this locus, we have characterized the breakpoint regions at a novel constitutional chromosome translocation (t(1;7)(q42;p15)), found in a child with WT and skeletal abnormalities. We identified two genes that were interrupted by the translocation: the parathyroid hormone-responsive B1 gene (PTH-B1) at 7p and obscurin at 1q. With no evidence for LOH at 1q42, we focused on the characterization of PTH-B1. We detected novel alternately spliced isoforms of PTH-B1, which were expressed in a wide range of adult and foetal tissues. Importantly, expression of two isoforms were disrupted in the WT of the t(1;7) patient. We also identified an additional splice isoform expressed only in 7p LOH tumours. The disruption of PTH-B1 by the t(1;7), together with aberrant splicing in sporadic WTs, suggests that PTH-B1 is a candidate for the 7p Wilms' tumour suppressor gene.

Bacteriophage grows in both IHF

No abstract

The N protein of phage acts with Escherichia coli Nus proteins at RNA sites, NUT, to modify RNA polymerase (RNAP) to a form that overrides transcription terminators. These interactions have been thought to be the primary determinants of the effectiveness of N-mediated antitermination. We present evidence that the associated promoter, in this case the early P R promoter, can influence N-mediated modification of RNAP even though modification occurs at a site (NUTR) located downstream of the intervening cro gene. As predicted by genetic analysis and confirmed by in vivo transcription studies, a combination of two mutations in P R , at positions ؊14 and ؊45 (yielding P R-GA ), reduces effectiveness of N modification, while an additional mutation at position ؊30 (yielding P R-GCA ) suppresses this effect. In vivo, the level of P R-GA -directed transcription was twice as great as the wild-type level, while transcription directed by P R-GCA was the same as that directed by the wild-type promoter. However, the rate of open complex formation at P R-GA in vitro was roughly one-third the rate for wild-type P R . We ascribe this apparent discrepancy to an effect of the mutations in P R-GCA on promoter clearance. Based on the in vivo experiments, one plausible explanation for our results is that increased transcription can lead to a failure to form active antitermination complexes with NUT RNA, which, in turn, causes failure to read through downstream termination sites. By blocking antitermination and thus expression of late functions, the effect of increased transcription through nut sites could be physiologically important in maintaining proper regulation of gene expression early in phage development.Expression of the delayed-early genes of coliphage is regulated by transcription termination and antitermination (19). Transcription initiating at the two early promoters P L and P R partially terminates at terminators t L1 and t R1 , respectively (Fig. 1A). Early transcription from P L results in production of N protein, which acts together with a number of host factors (Nus proteins) at NUT sites in nascent-early transcripts with RNA polymerase (RNAP) to form a transcription complex that is resistant to both intrinsic (Rho-independent) and Rhodependent terminators. Escherichia coli proteins that combine with N and NUT RNA to modify RNAP include NusA, NusB, ribosomal protein S10 (NusE), and NusG (10,23,40,43,55).Two classes of mutations in nus genes have been isolated. Class 1 mutations reduce effective N action, while class 2 mutations suppress the action of class 1 mutations by restoring the effectiveness of N in the presence of a class 1 mutation. For example, the failure of E. coli nusA1 or nusE71 mutants to support N action can be suppressed by class 2 mutations in either nusB or nusG (50,52). In addition to these class 2 nus mutations, a point mutation in rpoA, encoding the ␣ subunit of RNAP, suppresses the effects of nusA1 or nusE71 (47).With the exception of N, all phage-encoded factors required for lytic development ...