Stanniocalcin-1 protein expression profile and mechanisms in proliferation and cell death pathways in prostate cancer.

Prostate cancer (PCa) is one of the most prevalent male tumours. Stanniocalcin-1 (STC1) is a glycoprotein and, although the role of STC1 in human cancer is poorly understood, it is suggested to be involved in the development and progression of different neoplasms. This study investigated the protein expression profile of STC1 in PCa and benign prostatic hyperplasia (BPH) samples and STC1 signalling during cell proliferation and cell death in vitro using cell lines. We found higher levels of STC1 in PCa when compared to BPH tissue and that STC1 inhibited forskolin stimulation of cAMP in PC-3 cells. A monoclonal antibody against STC1 was effective in reducing cell proliferation, in promoting cell cycle arrest, and in increasing apoptosis in the same cells. Since STC1 acts as a regulator of prostatic tissue signalling, we suggest that this protein is a novel candidate biomarker for prostate tumour clinical progression and a potential therapeutic target.

Duplication of Dio3 genes in teleost fish and their divergent expression in skin during flatfish metamorphosis.

Deiodinase 3 (Dio3) plays an essential role during early development in vertebrates by controlling tissue thyroid hormone (TH) availability. The Atlantic halibut (Hippoglossus hippoglossus) possesses duplicate dio3 genes (dio3a and dio3b). Expression analysis indicates that dio3b levels change in abocular skin during metamorphosis and this suggests that this enzyme is associated with the divergent development of larval skin to the juvenile phenotype. In larvae exposed to MMI, a chemical that inhibits TH production, expression of dio3b in ocular skin is significantly up-regulated suggesting that THs normally modulate this genes expression during this developmental event. The molecular basis for divergent dio3a and dio3b expression and responsiveness to MMI treatment is explained by the multiple conserved TREs in the proximal promoter region of teleost dio3b and their absence from the promoter of dio3a. We propose that the divergent expression of dio3 in ocular and abocular skin during halibut metamorphosis contributes to the asymmetric pigment development in response to THs.

Divergence of duplicate POMC genes in gilthead sea bream Sparus auratus.

Proopiomelanocorticotrophin (POMC) in vertebrates is produced in the pituitary gland and undergoes post-translational processing to give rise to a range of biologically active peptides. Teleosts possess 2-3 different POMC transcripts which have been proposed to have originated from a whole or partial genome duplication. In the present study 2 transcripts of gilthead sea bream POMC (sbPOMC-α1 and α2) were cloned and characterised. sbPOMC-α1 is expressed principally in the melanotroph cells of the pars intermedia (PI) and sbPOMC-α2 is expressed in the corticotroph cells of the rostral pars distalis and probably also in the PI. The 2 sbPOMC transcripts have a differential tissue distribution in extra-pituitary sites. An appraisal of POMC evolution indicates sbPOMCs belong to one of the two main clades that exist in teleosts and that overall a non conservative process of gene loss occurred in this infraclass.

The secretin G-protein-coupled receptor family: teleost receptors.

Twenty-one members of the secretin family (family 2) of G-protein-coupled receptors (GPCRs) were identified via directed cloning and data-mining of the Fugu Genome Consortium database, representing the most comprehensive description of secretin GPCRs in a teleost fish to date. Duplicated genes were identified for many of the family members, namely the receptors for pituitary adenylate cyclase-activating polypeptide (PACAP)/vasoactive intestinal peptide (VIP), calcitonin, calcitonin gene-related peptide (CGRP), growth hormone releasing hormone (GHRH), glucagon receptor/glucagon-like peptide (GLP) and parathyroid hormone-related peptide (PTHrP)/PTH. Mining of other teleost genomes (zebrafish and Tetraodon) revealed that the duplicated genes identified in the Takifugu genome were also present in these fish. Additional database searching of the Escherichia coli, yeast, Drosophila, Caenorhabditis elegans and Ciona genomes revealed that the family 2 of GPCRs were only present in the multicellular organisms. Orthologues of all the human secretin receptors were identified with the exception of secretin itself. Additional database searches in the Fugu Genome Consortium database also failed to reveal a secretin ligand and so it is hypothesised that both the receptor and the ligand evolved after the divergence of teleost/tetrapod lineages. Phylogenetic analysis at both the protein and the DNA level provided strong support for each of the individual receptor family groupings, but weak support between groups, making evolutionary inferences difficult. A more critical analysis of the PACAP/VIP receptor family confirmed previous hypotheses that the vasoactive intestinal peptide receptor (VPAC(1)R) gene is the ancestral form of the receptor.

Duplicated receptors for VIP and PACAP (VPAC1R and PAC1R) in a teleost fish, Fugu rubripes.

Two principal groups of receptors orthologous with human PAC1R and VPAC1R and were identified and characterised at the genomic level in the teleost fish Fugu rubripes. An additional group orthologous with VPAC2R was also identified and partially characterised. In Fugu, gene duplication of each of the PAC1Rs, VPAC1Rs and VPAC2Rs appears to have occurred. The topology of the tree surrounding the Fugu duplications and other isolated piscine sequences indicates that the duplication events for these six genes clearly preceded the speciation event leading to the Cypriniformes and Tetraodontiformes and is probably teleost-specific. Overall, the combined pattern of gene expression for each pair of duplicated genes mirrored the expression in other vertebrates. However, within each pair of duplicates further specialisation had occurred, with each demonstrating differential tissue distribution profiles suggesting they that may be responsible for the divergent action of the ligands, vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP). The Fugu VPAC1R gene regions showed conserved synteny with human chromosome 3p21.3 and also C. elegans chromosome X, indicating that the putative ancestral human chromosome 3 region may be equivalent to chromosome X in Caenorhabditis elegans.

Isolation of a novel aquaglyceroporin from a marine teleost (Sparus auratus): function and tissue distribution.

The aquaporins (formerly called the major intrinsic protein family) are transmembrane channel proteins. The family includes the CHIP group, which are functionally characterised as water channels and the GLP group, which are specialised for glycerol transport. The present study reports the identification and characterisation of a novel GLP family member in a teleost fish, the sea bream Sparus auratus. A sea bream aquaporin (sbAQP) cDNA of 1047 bp and encoding a protein of 298 amino acids was isolated from a kidney cDNA library. Functional characterization of the sbAQP using a Xenopus oocyte assay revealed that the isolated cDNA stimulated osmotic water permeability in a mercury-sensitive manner and also stimulated urea and glycerol uptake. Northern blotting demonstrated that sbAQP was expressed at high levels in the posterior region of the gut, where two transcripts were identified (1.6 kb and 2 kb), and in kidney, where a single transcript was present (2 kb). In situ hybridisation studies with a sbAQP riboprobe revealed its presence in the lamina propria and smooth muscle layer of the posterior region of the gut and in epithelial cells of some kidney tubules. sbAQP was also present in putative chloride cells of the gill. Phylogenetic analysis of sbAQP, including putative GLP genes from Fugu rubripes, revealed that it did not group with any of the previously isolated vertebrate GLPs and instead formed a separate group, suggesting that it may be a novel GLP member.