ABSTRACT
Alternative splicing of cardiac troponin T (cTNT) exon 5 undergoes a developmentally regulated switch such that exon inclusion predominates in embryonic, but not adult, striated muscle. We previously described four muscle-specific splicing enhancers (MSEs) within introns flanking exon 5 in chicken cTNT that are both necessary and sufficient for exon inclusion in embryonic muscle. We also demonstrated that CUG-binding protein (CUG-BP) binds a conserved CUG motif within a human cTNT MSE and positively regulates MSE-dependent exon inclusion. Here we report that CUG-BP is one of a novel family of developmentally regulated RNA binding proteins that includes embryonically lethal abnormal vision-type RNA binding protein 3 (ETR-3). This family, which we call CELF proteins for CUG-BP- and ETR-3-like factors, specifically bound MSE-containing RNAs in vitro and activated MSE-dependent exon inclusion of cTNT minigenes in vivo. The expression of two CELF proteins is highly restricted to brain. CUG-BP, ETR-3, and CELF4 are more broadly expressed, and expression is developmentally regulated in striated muscle and brain. Changes in the level of expression and isoforms of ETR-3 in two different developmental systems correlated with regulated changes in cTNT splicing. A switch from cTNT exon skipping to inclusion tightly correlated with induction of ETR-3 protein expression during differentiation of C2C12 myoblasts. During heart development, the switch in cTNT splicing correlated with a transition in ETR-3 protein isoforms. We propose that ETR-3 is a major regulator of cTNT alternative splicing and that the CELF family plays an important regulatory role in cell-specific alternative splicing during normal development and disease.
Subject(s)
Alternative Splicing , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Adult , Amino Acid Sequence , Animals , Base Sequence , Brain/growth & development , Brain/metabolism , CELF Proteins , CELF1 Protein , Cell Line , Chickens , DNA Primers/genetics , Enhancer Elements, Genetic , Exons , Female , Gene Expression , Humans , Male , Molecular Sequence Data , Muscle Development , Muscle, Skeletal/growth & development , Muscle, Skeletal/metabolism , Nerve Tissue Proteins , Ribonucleoproteins/genetics , Sequence Homology, Amino Acid , Tissue Distribution , Troponin T/geneticsABSTRACT
OBJECTIVE: To assess the prognostic value of Führman's nuclear grade and to compare it to various clinical and histological prognostic factors of renal carcinomas. PATIENTS AND METHOD: Single-centre retrospective study of 102 patients operated for renal tumours between January 1985 and December 1990 (mean follow-up: 8.2 years). Prognostic assessment was studied from survival curves. RESULTS: The prognostic factors most closely correlated with survival were, in decreasing order, metastatic invasion, nuclear grade, stage of local extension and lymph node invasion. A significant (p < 0.01) survival difference was only observed between Führman grade 2 and grade 3 tumours. This difference was accentuated (p < 0.001) when grade 1 and 2 tumours were compared to grade 3 and 4 tumours. Führman's nuclear grade is independent of the side affected, the tumour volume, its multifocal nature, microscopic venous invasion and metastatic invasion at the time of diagnosis. Führman's nuclear grade is correlated with invasion of fat, the presence of a contingent of eosinophilic cells, stage of local extension, lymph node invasion and the subsequent development of metastases. CONCLUSION: This study confirms the importance of Führman's nuclear grade among the various prognostic factors of renal carcinomas and quantifies its value with respect to other prognostic factors.
Subject(s)
Cell Nucleus/pathology , Kidney Neoplasms/mortality , Kidney Neoplasms/pathology , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Prognosis , Retrospective Studies , Survival RateSubject(s)
Chemical and Drug Induced Liver Injury, Chronic/etiology , Drug Eruptions/etiology , Platelet Aggregation Inhibitors/adverse effects , Ticlopidine/adverse effects , Aged , Female , Humans , Hypersensitivity, Delayed/etiology , Platelet Aggregation Inhibitors/therapeutic use , Ticlopidine/therapeutic useABSTRACT
The transcription factor GHF1/Pit1, required for the expression of the prolactin (PRL) and other pituitary-specific genes, is highly conserved from fish to mammals but the mechanisms by which it activates transcription are poorly understood. The activity of the promoter (-627/+15 region) of the rainbow trout PRL (tPRL) gene fused to the luciferase reporter gene was studied using GHF1-expressing rat pituitary GC cells. Nuclear extracts of GC cells produced five GHF1-specific footprints in the tPRL promoter, with the position of the two most proximal ones being highly conserved in trout and mammalian GHF1-regulated genes. Deletional and mutational analyses of the tPRL promoter showed that the most proximal GHF1 site alone is sufficient to confer sub-maximal GHF1-dependent transcriptional activity and that a glucocorticoid response element-like motif mediates dexamethasone stimulation. It is suggested that GHF1 molecules bound to different sites of the tPRL promoter cannot interact simultaneously with the transcriptional apparatus. Moreover, GHF1 and the ligand-bound glucocorticoid receptor tethered to their cognate elements in the promoter could cooperate to enhance transcription by interacting simultaneously with different members of the basal transcriptional complex.
