AR intragenic deletions linked to androgen receptor splice variant expression and activity in models of prostate cancer progression.

Reactivation of the androgen receptor (AR) during androgen depletion therapy (ADT) underlies castration-resistant prostate cancer (CRPCa). Alternative splicing of the AR gene and synthesis of constitutively active COOH-terminally truncated AR variants lacking the AR ligand-binding domain has emerged as an important mechanism of ADT resistance in CRPCa. In a previous study, we demonstrated that altered AR splicing in CRPCa 22Rv1 cells was linked to a 35-kb intragenic tandem duplication of AR exon 3 and flanking sequences. In this study, we demonstrate that complex patterns of AR gene copy number imbalances occur in PCa cell lines, xenografts and clinical specimens. To investigate whether these copy number imbalances reflect AR gene rearrangements that could be linked to splicing disruptions, we carried out a detailed analysis of AR gene structure in the LuCaP 86.2 and CWR-R1 models of CRPCa. By deletion-spanning PCR, we discovered a 8579-bp deletion of AR exons 5, 6 and 7 in the LuCaP 86.2 xenograft, which provides a rational explanation for synthesis of the truncated AR v567es AR variant in this model. Similarly, targeted resequencing of the AR gene in CWR-R1 cells led to the discovery of a 48-kb deletion in AR intron 1. This intragenic deletion marked a specific CWR-R1 cell population with enhanced expression of the truncated AR-V7/AR3 variant, a high level of androgen-independent AR transcriptional activity and rapid androgen independent growth. Together, these data demonstrate that structural alterations in the AR gene are linked to stable gain-of-function splicing alterations in CRPCa.

Accumulation of extracellular proteins bearing unique proline-rich motifs in intercellular spaces of the legume nodule parenchyma.

Nodulins encoding repetitive proline-rich cell wall proteins (PRPs) are induced during early interactions with rhizobia, suggesting a massive restructuring of the plant extracellular matrix during infection and nodulation. However, the proteins corresponding to these gene products have not been isolated or characterized, nor have cell wall localizations been confirmed. Posttranslational modifications, conformation, and interactions with other wall polymers are difficult to predict on the basis of only the deduced amino acid sequence of PRPs. PsENOD2 is expressed in nodule parenchyma tissue during nodule organogenesis and encodes a protein with distinctive PRP motifs that are rich in glutamate and basic amino acids. A database search for the ENOD2 signature motifs indicates that similar proteins may have a limited phylogenetic distribution, as they are presently only known from legumes. To determine the ultrastructural location of the proteins, antibodies were raised against unique motifs from the predicted ENOD2 sequence. The antibodies recognized nodule-specific proteins in pea (Pisum sativum), with a major band detected at 110 kDa, representing a subset of PRPs from nodules. The protein was detected specifically in organelles of the secretory pathway and intercellular spaces in the nodule parenchyma, but it was not abundant in primary walls. Similar proteins with an analogous distribution were detected in soybean (Glycine max). The use of polyclonal antibodies raised against signature motifs of extracellular matrix proteins thus appears to be an effective strategy to identify and isolate specific structural proteins for functional analysis.

MetaFam: a unified classification of protein families. I. Overview and statistics.

MOTIVATION: Protein sequence classification is becoming an increasingly important means of organizing the voluminous data produced by large-scale genome sequencing projects. At present, there are several independent classification methods. To aid the general classification effort, we have created a unified protein family resource, MetaFam. MetaFam is a protein family classification built upon 10 publicly-accessible protein family databases (Blocks + DOMO, Pfam, PIR-ALN, PRINTS, PROSITE, ProDom, PROTOMAP, SBASE, and SYSTERS). MetaFam's family 'supersets', as we call them, are created automatically using set-theory to compare families among the databases. Families of one database are matched to those in another when the intersection of their members exceeds all other possible family pairings between the two databases. Pairwise family matches are drawn together transitively to create a new list of protein family supersets. RESULTS: MetaFam family supersets have several useful features: (1) each superset contains more members than the families from which it is composed, because each of the component family databases only works with a subset of our full non-redundant set of proteins; (2) conflicting assignments can be pinpointed quickly, since our analysis identifies individual members that are in conflict with the majority consensus; (3) family descriptions that are absent from automated databases can frequently be assigned; (4) statistics have been computed comparing domain boundaries, family size distributions, and overall quality of MetaFam supersets; (5) the supersets have been loaded into a relational database to allow for complex queries and visualization of the connections among families in a superset and the consensus of individual domain members; and (6) the quality of individual supersets has been assessed using numerous quantitative measures such as family consistency, connectedness, and size. We anticipate this new resource will be particularly useful to genomic database curators.

MetaFam: a unified classification of protein families. II. Schema and query capabilities.

MOTIVATION: Protein sequence and family data is accumulating at such a rapid rate that state-of-the-art databases and interface tools are required to aid curators with their classifications. We have designed such a system, MetaFam, to facilitate the comparison and integration of public protein sequence and family data. This paper presents the global schema, integration issues, and query capabilities of MetaFam. RESULTS: MetaFam is an integrated data warehouse of information about protein families and their sequences. This data has been collected into a consistent global schema, and stored in an Oracle relational database. The warehouse implementation allows for quick removal of outdated data sets. In addition to the relational implementation of the primary schema, we have developed several derived tables that enable efficient access from data visualization and exploration tools. Through a series of straightforward SQL queries, we demonstrate the usefulness of this data warehouse for comparing protein family classifications and for functional assignment of new sequences.

The MetaFam Server: a comprehensive protein family resource.

MetaFam is a comprehensive relational database of protein family information. This web-accessible resource integrates data from several primary sequence and secondary protein family databases. By pooling together the information from these disparate sources, MetaFam is able to provide the most complete protein family sets available. Users are able to explore the interrelationships among these primary and secondary databases using a powerful graphical visualization tool, MetaFamView. Additionally, users can identify corresponding sequence entries among the sequence databases, obtain a quick summary of corresponding families (and their sequence members) among the family databases, and even attempt to classify their own unassigned sequences. Hypertext links to the appropriate source databases are provided at every level of navigation. Global family database statistics and information are also provided. Public access to the data is available at http://metafam.ahc.umn.edu/.

PANAL: an integrated resource for Protein sequence ANALysis.

SUMMARY: We present PANAL, an integrated resource for protein sequence analysis. The tool allows the user to simultaneously search a protein sequence for motifs from several databases, and to view the result as an intuitive graphical summary.