Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and trans-activation ability

<p>Abstract</p> <p>Background</p> <p>Peroxisome proliferator-activated receptor delta (PPARδ) is a member of the nuclear receptor superfamily. Numerous studies have aimed at unravelling the physiological role of PPARδ as a transcriptional regulator whereas the regulation of PPARδ gene expression has been less studied.</p> <p>Results</p> <p>The principal transcription start site in the human PPARδ gene identified here is positioned upstream of exon 1, although four alternative 5'-ends related to downstream exons were identified. The demonstration of multiple 5'-UTR splice variants of PPARδ mRNA, with an impact on translation efficiency, suggests a translational regulation of human PPARδ expression. Five untranslated exons identified in this study contribute to the variability among the 5'-UTRs of human PPARδ mRNAs. Moreover, <it>in vitro </it>studies of a 3'-splice transcript encoding a truncated variant of PPARδ (designated PPARδ2) show that this isoform constitutes a potential dominant negative form of the receptor.</p> <p>Conclusion</p> <p>We propose that alternative splicing of human PPARδ constitutes an intrinsic role for the regulation of PPARδ expression and thus activity, and highlight the significance of alternative splicing of this nuclear receptor in physiology and disease.</p

High intratumoral dihydrotestosterone is associated with antiandrogen resistance in VCaP prostate cancer xenografts in castrated mice

Antiandrogen treatment resistance is a major clinical concern in castration-resistant prostate cancer (CRPC) treatment. Using xenografts of VCaP cells we showed that growth of antiandrogen resistant CRPC tumors were characterized by a higher intratumor dihydrotestosterone (DHT) concentration than that of treatment responsive tumors. Furthermore, the slow tumor growth after adrenalectomy was associated with a low intratumor DHT concentration. Reactivation of androgen signaling in enzalutamide-resistant tumors was further shown by the expression of several androgen-dependent genes. The data indicate that intratumor DHT concentration and expression of several androgen-dependent genes in CRPC lesions is an indication of enzalutamide treatment resistance and an indication of the need for further androgen blockade. The presence of an androgen synthesis, independent of CYP17A1 activity, has been shown to exist in prostate cancer cells, and thus, novel androgen synthesis inhibitors are needed for the treatment of enzalutamide-resistant CRPC tumors that do not respond to abiraterone.Peer reviewe

Allele-specific regulation of MTTP expression influences the risk of ischemic heart disease

Peer reviewe

Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability-8

<p><b>Copyright information:</b></p><p>Taken from "Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability"</p><p>http://www.biomedcentral.com/1471-2199/8/70</p><p>BMC Molecular Biology 2007;8():70-70.</p><p>Published online 16 Aug 2007</p><p>PMCID:PMC2045109.</p><p></p>aque (; chr4) and chimpanzee (; chr6) orthologous genes are shown. Conserved sequences are defined as coding exons (blue), untranslated exons (yellow) and introns (pink). The locations of the novel untranslated human exons (2a-2e) in the PPARδ gene are indicated by arrows. The percent identity of the masked (unaligned) sequence harbouring exons 2b and 2c obtained by ClustalW alignment is indicated in the defined area, likewise the lack of identity over the masked region containing exon 2d is indicated by horizontal lines. A schematic view showing the locations of previously identified exons in human PPARδ gene are aligned above the conservation profile for orientation

Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability-7

<p><b>Copyright information:</b></p><p>Taken from "Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability"</p><p>http://www.biomedcentral.com/1471-2199/8/70</p><p>BMC Molecular Biology 2007;8():70-70.</p><p>Published online 16 Aug 2007</p><p>PMCID:PMC2045109.</p><p></p>ed for by the 63 kb versus 50 kb separating exon 2 and the first coding exon (4 or 3) in human and mouse genes, respectively. The relative positions of exons along the genes are given, specifying exons that are conserved between species (boxes) and species-specific exons (boxes). indicate the position of the initiation codon ATG and the stop codon TAA, respectively, with the intervening coding exons

Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability-3

<p><b>Copyright information:</b></p><p>Taken from "Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability"</p><p>http://www.biomedcentral.com/1471-2199/8/70</p><p>BMC Molecular Biology 2007;8():70-70.</p><p>Published online 16 Aug 2007</p><p>PMCID:PMC2045109.</p><p></p

Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability-5

<p><b>Copyright information:</b></p><p>Taken from "Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability"</p><p>http://www.biomedcentral.com/1471-2199/8/70</p><p>BMC Molecular Biology 2007;8():70-70.</p><p>Published online 16 Aug 2007</p><p>PMCID:PMC2045109.</p><p></p>DNA pUC19 (100 ng), untreated (control) or treated with 1 nM, 10 nM or 100 nM of the PPARδ specific ligand GW501516. . Co-transfection of pFABLuc reporter construct (200 ng) with constant amount of expression vector for PPARδ1 (50 ng) and increasing concentrations of the expression vector for PPARδ2 (50 to 200 ng) and treatment with 10 nM or 100 nM GW501516. Transfection of the pFABLuc vector alone was used as a control. Plasmid DNA pUC19 was added to ensure equal amount of DNA in all transfections. Plasmid pSV-β-galactosidase control vector (Promega) (260 ng) was co-transfected in all experiments for normalization of the transfection efficiency. The data presented are the mean (± SD) luciferase/β-galactosidase ratios of three independent transfections determined in quadruplicates. The activities are expressed as relative values setting the value of untreated control to 1 () or the value obtained without PPARδ2 expression plasmid to 1 (). C. Western blot analysis with nuclear extracts prepared from untransfected HeLa cells (Contr) and HeLa cells transfected with the expression vectors encoding PPARδ1 or PPARδ2, respectively, using a PPARδ antibody raised against the N-terminal region of the nuclear receptor (sc-7197, Santa Cruz Biotechnology). The sizes of standard molecule markers are given on the left side

Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability-6

<p><b>Copyright information:</b></p><p>Taken from "Alternative splicing of human peroxisome proliferator-activated receptor delta (PPARdelta):effects on translation efficiency and -activation ability"</p><p>http://www.biomedcentral.com/1471-2199/8/70</p><p>BMC Molecular Biology 2007;8():70-70.</p><p>Published online 16 Aug 2007</p><p>PMCID:PMC2045109.</p><p></p>XRα or mock lysate as described in "Methods". Unlabelled ACO-PPRE was added at 100-fold molar excess for competition. Supershift experiments were carried out using a PPARδ antibody directed against the N-terminal region of human PPARδ. indicate the positions of the shifted and the supershifted bands. None of the receptors (PPARδ1, PPARδ2 or RXRα) alone could be supershifted in the presence of the PPARδ antibody (data not shown)