Growth and differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15, GDF9B) are oocyte-derived proteins essential for the growth and function of ovarian follicles. Moreover, ovine (o) GDF9 and oBMP15 cooperate to increase both (3)H-thymidine incorporation and alpha-inhibin production and to inhibit progesterone production by rat or ovine granulosa cells. Although the receptors through which these proteins act individually have been determined, the receptor(s) involved in mediating the cooperative effects of GDF9 and BMP15 is (are) unknown. In this study, the effects of the extracellular domains of the types I and II TGFbeta receptors on (3)H-thymidine incorporation by rat granulosa cells stimulated by oGDF9 and oBMP15 were investigated. Stimulation of (3)H-thymidine incorporation was completely blocked by the BMP receptor II (BMPRII) extracellular domain but unaffected by any other type II or any type I receptor. These results suggest that the initial interaction of oGDF9 and oBMP15 is with BMPRII and that a type I receptor is either recruited or already associated with BMPRII to mediate the cooperative effects of these growth factors.

Nuclear localization and high levels of the Y-box binding protein YB1 appear to be important indicators of drug resistance and tumor prognosis. YB1 also interacts with the p53 tumor suppressor protein. In this paper, we explore a role for p53 in the nuclear localization of YB1. We report that various genotoxic stresses induce nuclear localization of YB1 in a small proportion of treated cells, but only in cells with wild-type p53. We go on to show directly that functional p53 is required for YB1 to translocate to the nucleus. Tumor-associated p53 mutants however are attenuated for YB1 nuclear localization as are mutants mutated in the proline-rich domain of p53. These data link the DNA-damage response of p53 to YB1 nuclear translocation. In addition, we find that YB1 inhibits p53-induced cell death and its ability to transactivate promoters of genes involved in cell death signaling. Together these data suggest that some forms of p53 cause YB1 to accumulate in the nucleus, which in turn inhibits p53 activity. These results provide a possible explanation for the correlation of nuclear YB1 with drug resistance and poor prognosis in some tumor types, and for the first time implicate p53 in the process of nuclear translocation.

Treacher Collins syndrome (TCS) is an autosomal dominant disorder of craniofacial development, the features of which include conductive hearing loss and cleft palate. Recently, the demonstration of a series of 10 mutations within a partial-length cDNA clone have indicated that the TCS gene (TCOF1) has been positionally cloned. Although it has been shown that the gene is expressed in a wide variety of fetal and adult tissues, database sequence comparisons have failed to provide significant information on the function of the gene. In the current investigation, a combination of cDNA library screening and rapid amplification of cDNA ends has permitted the isolation of the complete coding sequence of TCOF1, which is encoded by 26 exons and predicts a low complexity, serine/alanine-rich protein of approximately 144 kD. The use of a variety of bioinformatics tools has resulted in the identification of repeated units within the gene, each of which maps onto an individual exon. The predicted protein Treacle contains numerous potential phosphorylaiton sites, a number of which map to similar positions within the repeated units, and shows weak but significant homology to the nucleolar phosphoproteins. Although the precise function of Treacle remains unknown, these observations suggest that phosphorylation may be important for its role in early embryonic development and that it may play a role in nucleolar-cytoplasmic shuttling. The information presented in this study will allow continued mutation analysis in families with a history of TCS and should facilitate continued experimentation to shed further light on the function of the gene/protein during development of the craniofacial complex.

Treacher Collins syndrome is an autosomal dominant disorder of craniofacial development the features of which include conductive hearing loss and cleft palate. Recently, the Treacher Collins syndrome gene (TCOF1) has been positionally cloned and a series of five mutations within the coding sequence of the gene identified. In the current investigation, seven exons of TCOF1 have been identified which has permitted the identification of additional mutations in the gene. The mutations that have been identified are three distinct deletions and an insertion, which cause a frameshift, and a missense mutation which inactivates a donor splice site with extension of transcription into the intron. To date, all 10 of the mutations which have been reported result in a premature termination codon and are unique to a given family. As these mutations are spread throughout the gene, these observations provide further support for the hypothesis that Treacher Collins syndrome results from haploinsufficiency, although a dominant negative effect cannot, at this stage, be excluded.

Treacher Collins syndrome is an autosomal dominant disorder of craniofacial development, which has been localized to chromosome 5q32-33.1. In the present study, the isolation of new polymorphic markers has allowed the identification of overlapping recombination events in two affected individuals. Extension of the transcription map of the critical region proximally has resulted in the isolation of a new gene (which has been named Treacle) of unknown function. The identification of different mutations in five unrelated families, all of which would result in premature termination of the predicted protein, indicates that the Treacher Collins syndrome gene has been positionally cloned.