SEARCH · PubMed Health

Results for “Alternative Splicing”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,117 records · Page 62Linked to original sources

PubMed1997

Alternatively spliced forms of the cGMP-gated channel in human keratinocytes.

Alternatively spliced forms of the alpha subunit of the cGMP-gated channel have been cloned from human keratinocytes. One form encodes a complete channel which is almost identical to the rod photoreceptor. A second spliced variant would encode a protein missing a portion of the intracellular hydrophilic domain and the putative first transmembrane domain. Both complete and spliced variants of the channel also were found in epidermis. The expression of the complete form of the channel was induced by levels of extracellular calcium which promote keratinocyte differentiation. The cGMP-gated channel may play an important role in calcium induced keratinocyte differentiation by mediating Ca2+ entry.

Alternative Splicing↗

PubMed2004

Alternative splicing modulates Disabled-1 (Dab1) function in the developing chick retina.

The Reelin-Disabled 1 (Dab1)-signaling pathway plays a critical role in neuronal cell positioning in the brain. We have isolated two alternatively spliced variants of Dab1 from chick retina, an early form (chDab1-E) expressed in undifferentiated cells and a late form (chDab1-L) expressed in amacrine and ganglion cells. A key difference between the two forms is the exclusion in chDab1-E of two Src-related tyrosine kinase recognition sites implicated in Reelin-mediated Dab1 tyrosine phosphorylation. Retinal cultures transfected with a chDab1-L expression construct undergo a dramatic change in morphology, accompanied by the formation of numerous thin elongated processes, increased tyrosine phosphorylation, activation of Src family kinase(s) and increased levels of the axonal outgrowth protein growth-associated protein-43. In contrast, chDab1-E transfectants retain an undifferentiated morphology. Mutational analysis implicates a specific tyrosine (tyr-198) in the morphological and biochemical alterations associated with chDab1-L expression. We propose that alternative splicing of chDab1 represents an effective and flexible way of regulating the Reelin-Dab1-signaling pathway in a mixed cell population, by ensuring that secreted Reelin activates the signaling cascade only in target neuronal cells.

Alternative Splicing↗

PubMed1999

Expression of novel alternatively spliced isoforms of the oct-1 transcription factor.

Analysis of the alternatively spliced isoforms of the human and mouse oct-1 genes, combined with their exon-intron structure, show a high level of evolutionary conservation between these two species. The differential expression of several oct-1 isoforms was examined by reverse transcription-polymerase chain reaction performed on the 3' region of the murine oct-1 cDNA. Variations in the relative levels and patterns of expression of the isoforms were found among different tissues. Three novel isoforms originating from the 3'-distal region of oct-1, were isolated and sequenced: Two were derived from testis, and one from myeloma cells. Splicing out of different exons as revealed in the structure of these isoforms results in reading frameshifts that presumably lead to the expression of shortened Oct-1 proteins, with distinct C-terminal tails. Altogether, six out of the eight known murine oct-1 isoforms may have distinct C-termini, implying that these multiple tails have different functional roles in cellular differentiation and physiology.

Alternative Splicing↗

PubMed2005

Multiple alternative splicing and differential expression of dmrt1 during gonad transformation of the rice field eel.

Morphologically distinct males and females are observed throughout the animal kingdom. Why and how sex evolved and is maintained in most living organisms remains a key question in cellular and evolutionary biology. Here we report that four isoforms of dmrt1 (dsx- and mab3-related transcription factor 1) are generated in testis, ovotestis, and ovary by alternative splicing in the rice field eel, a fresh water fish that undergoes natural sex reversal from female to male during its life cycle. These transcripts encode four different size proteins with 301, 196, 300, and 205 amino acids. Like fly doublesex splicing, the dmrt1 of the rice field eel is also alternatively spliced at the 3' region, which generates diverse isoforms in gonads by alternative use of 3' sequences. Not only is dmrt1 expressed specifically in gonads, but its multiple isoforms are differentially coexpressed in gonadal epithelium during gonad transformation. Expression levels of a and b isoforms of dmrt1 ranged from low to high (ovary < ovotestis I < ovotestis II < ovotestis III < testis), based on comparisons of mean values from real-time fluorescent quantitative reverse transcription-polymerase chain reaction analysis. The overall expression level of dmrt1 b was much lower than that of dmrt1 a. Expression of dmrt1 d was not only low, but it also did not change significantly during sex transformation. The differential expression of dmrt1 isoforms may also be regulated by their 3' untranslated regions (UTRs), although these 3' UTRs do not contribute to intracellular localization of the Dmrt1 protein. These results provide new insight into roles of regulation at the level of splicing of dmrt1 in governing the sex differentiation cascade.

3' Untranslated Regions↗

PubMed1990

The alpha 1 chain of type XIII collagen consists of three collagenous and four noncollagenous domains, and its primary transcript undergoes complex alternative splicing.

We have recently reported a characterization of cDNA clones that encode an apparently novel human collagen that undergoes alternative splicing. These cDNAs covered one-third of the corresponding 2.5-2.8-kilobase mRNAs. We have now determined the complete primary structure of the protein encoded by several overlapping cDNAs isolated from a human endothelial cell library. Since the deduced translation product of the cDNAs is different in structure from all other collagen types, we have given the collagen chain encoded by the cDNAs the designation alpha 1 (XIII). The deduced polypeptide consists of three collagenous domains and four noncollagenous domains, two of them separating the collagenous domains and two located at the N-terminal and C-terminal ends of the polypeptide. Cysteine residues are found in three of the noncollagenous domains and also in the extreme N-terminal collagenous domain. Surprisingly, comparison of the nucleotide sequences encoded by the overlapping cDNA clones demonstrates that there are several alpha 1 (XIII) collagen mRNAs in HT-1080 human fibrosarcoma cells and human endothelial cells which differ in coding potential. Nuclease S1 mapping experiments suggest that these different mRNAs arise through alternative splicing of the precursor RNA at five locations within the coding region. This property makes type XIII collagen unique among all the collagen types studied so far. Its polypeptide length, therefore, may vary between 614 and 526 amino acids, depending on what internal splicing has taken place.

Amino Acid Sequence↗

PubMed1997

The region encoded by the alternatively spliced exon IIIA in mesenchymal fibronectin appears essential for chondrogenesis at the level of cellular condensation.

Fibronectin in the extracellular matrix of tissues acts as a substrate for cell adhesion and migration during development. Heterogeneity in the structure of fibronectin is largely due to the alternative splicing of at least three exons (IIIB, IIIA, and V) during processing of a single primary transcript. Fibronectin mRNA alternative splicing patterns change from B+A+V+ to B+A-V+ during chondrogenesis. In this report, immunohistochemical analysis demonstrates that while fibronectin protein containing the region encoded by exon IIIB is present throughout the limb at all stages of development, fibronectin protein containing the region encoded by exon IIIA disappears from cartilaginous regions just after condensation in vivo and in high-density mesenchymal micromass cultures in vitro. Treatment of mesenchymal micromass cultures prior to condensation with an antibody specific for the region encoded by exon IIIA disrupts the formation of cellular condensations and inhibits subsequent chondrogenesis in a dose- and time-dependent manner. Furthermore, microinjection of the exon IIIA antibody into embryonic chick limb primordia in vivo results in malformations characterized by smaller limbs and loss of limb skeletal elements. These results strongly suggest that the presence of the region encoded by exon IIIA in mesenchymal fibronectin is necessary for the condensation event that occurs during chondrogenesis.

Alternative Splicing↗

PubMed2000

The gas 5 gene shows four alternative splicing patterns without coding for a protein.

The murine gas5 gene was originally isolated based on its preferential expression in the growth arrest phase of the cell cycle. This gene contains 12 exons from which two alternatively spliced transcripts have been initially identified. More recently, it has been reported that both human and murine gas5 genes contain in their introns sequences homologous to the small nucleolar RNAs involved in the processing of ribosomal RNA. Here we report on the identification and analysis of the expression pattern of two novel alternatively spliced mouse gas5 mRNAs which contain no obvious open reading frame (ORF). Using antibodies generated against the putative amino acid sequence deduced from the gas5 cDNAs, we were not able to detect any Gas5 protein in cultured cells or murine tissues extracts. Even more definitive evidence that the gas5 gene may not encode a protein was obtained by cloning and sequencing the rat gas5 gene which revealed that the putative ORF is interrupted by a stop codon after the first 13 amino acids.

3T3 Cells↗

PubMed1998

A naturally occurring isoform of the human macrophage scavenger receptor (SR-A) gene generated by alternative splicing blocks modified LDL uptake.

The class A macrophage scavenger receptors (SR-A) are macrophage-specific trimeric integral membrane glycoproteins that have been implicated in many macrophage-associated physiological and pathological processes including atherosclerosis, Alzheimer's disease, and host defense. There are two forms of the receptor that have been previously cloned, and both are generated by alternative splicing of a single gene. Here we report the cloning of a third, alternatively spliced isoform of the human SR-A gene (type III hSR-A). The novel isoform is expressed in the human monocytic leukemia cell line THP-1 and also in primary human monocyte derived macrophages. When expressed in CHO-K1 cells, type III hSR-A does not internalize AcLDL despite having the domain shown to mediate this function in type I and II hSR-A. We show that type III protein has altered intracellular processing and is trapped within the endoplasmic reticulum, making it unable to perform endocytosis. Type III protein acts as a dominant negative isoform by reducing modified LDL uptake in CHO cells stably expressing either type I or type II SR-A. The demonstration that a naturally occurring splice variant of SR-A mRNA can act as a dominant negative isoform suggests a novel mechanism for regulation of scavenger receptor activity in macrophages.

Alternative Splicing↗

PubMed1993

Molecular analysis of human beta-arrestin-1: cloning, tissue distribution, and regulation of expression. Identification of two isoforms generated by alternative splicing.

The cDNA for human beta-arrestin-1 was cloned by polymerase chain reaction (PCR) and identified based on its remarkably high amino acid identity (98.6%) with the bovine sequence. Two alternatively spliced isoforms of human beta-arrestin-1, differing only in the presence or absence of 24 base pairs/8 amino acids within the sequence, were identified and called beta-arrestin-1A and beta-arrestin-1B, respectively. Both isoforms were found in all tissues tested. Southern blot analysis revealed the existence of a single gene for beta-arrestin-1, suggesting that the two isoforms are generated by alternative mRNA splicing. The possible presence of similar isoforms was investigated for the other members of the arrestin/beta-arrestin gene family by PCR. Two isoforms of arrestin were revealed in bovine peripheral blood leukocytes. The expression of beta-arrestin-1 was studied in several human tissues and cell types. High levels of beta-arrestin-1 mRNA and immunoreactivity were found in peripheral blood leukocytes. The possible regulation of the expression of beta-arrestin-1 was also investigated. Our work documents for the first time that the expression of beta-arrestin-1 is modulated by intracellular cAMP. Using two cell types, human endothelial cells and smooth muscle cells, we found that 6-8-h treatments with the cAMP-inducing agents cholera toxin, forskolin, iloprost, and isoproterenol raised beta-arrestin-1 mRNA by 2-4-fold. Forskolin preferentially increased beta-arrestin-1A expression in smooth muscle cells, as assessed by PCR. beta-Arrestin-1 immunoreactivity was 2-3-fold higher in smooth muscle cells exposed to forskolin for 8 h, compared with untreated controls. We conclude that (i) the finding of alternatively spliced isoforms of beta-arrestin-1 and arrestin documents a novel mechanism to generate diversity within the arrestin/beta-arrestin gene family; (ii) the abundant expression of beta-arrestin-1 in peripheral blood leukocytes further supports our previous suggestion of a major role for the beta ARK/beta-arrestin system in regulating receptor-mediated immune functions; (iii) the increased expression of beta-arrestin-1 by cAMP suggests a new mechanism for the regulation of receptor-mediated responses.

Alternative Splicing↗

PubMed2000

One-codon alternative splicing of the CpG MTase Dnmt1 transcript in mouse somatic cells.

The genomic methylation patterns in the mammalian somatic cells are presumably maintained by a single enzyme, dnmt1. In mouse, this DNA (cytosine-5)-methyltransferase, or CpG MTase, is encoded by the Dnmt1 gene. We now present evidence that in different tissues and cell types, the primary transcript of mouse dnmt1 is alternatively spliced to generate two poly-(A) RNAs of approximately similar abundance. This alternative splicing most likely originates from the existence of two tandemly arranged acceptor sites separated by only 3 nt. The two Dnmt1 mRNAs thus encode two CpG MTases differing by two amino acids. We discuss the implications of the discovery of two dnmt1 isozymes, instead of one enzyme as previously thought, in the somatic cells of both mouse and human.

Alternative Splicing↗

PubMed2003

Nova regulates GABA(A) receptor gamma2 alternative splicing via a distal downstream UCAU-rich intronic splicing enhancer.

Nova is a neuron-specific RNA binding protein targeted in patients with the autoimmune disorder paraneoplastic opsoclonus-myoclonus ataxia, which is characterized by failure of inhibition of brainstem and spinal motor systems. Here, we have biochemically confirmed the observation that splicing regulation of the inhibitory GABA(A) receptor gamma2 (GABA(A)Rgamma2) subunit pre-mRNA exon E9 is disrupted in mice lacking Nova-1. To elucidate the mechanism by which Nova-1 regulates GABA(A)Rgamma2 alternative splicing, we systematically screened minigenes derived from the GABA(A)Rgamma2 and human beta-globin genes for their ability to support Nova-dependent splicing in transient transfection assays. These studies demonstrate that Nova-1 acts directly on GABA(A)Rgamma2 pre-mRNA to regulate E9 splicing and identify an intronic region that is necessary and sufficient for Nova-dependent enhancement of exon inclusion, which we term the NISE (Nova-dependent intronic splicing enhancer) element. The NISE element (located 80 nucleotides upstream of the splice acceptor site of the downstream exon E10) is composed of repeats of the sequence YCAY, consistent with previous studies of the mechanism by which Nova binds RNA. Mutation of these repeats abolishes binding of Nova-1 to the RNA in vitro and Nova-dependent splicing regulation in vivo. These data provide a molecular basis for understanding Nova regulation of GABA(A)Rgamma2 alternative splicing and suggest that general dysregulation of Nova's splicing enhancer function may underlie the neurologic defects seen in Nova's absence.

Alternative Splicing↗

PubMed2000

Profilin II is alternatively spliced, resulting in profilin isoforms that are differentially expressed and have distinct biochemical properties.

We deduced the structure of the mouse profilin II gene. It contains five exons that can generate four different transcripts by alternative splicing. Two transcripts encode different profilin II isoforms (designated IIa and IIb) that have similar affinities for actin but different affinities for polyphosphoinositides and proline-rich sequences. Profilins IIa and IIb are also present in humans, suggesting that all mammals have three profilin isoforms. Profilin I is the major form in all tissues, except in the brain, where profilin IIa is most abundant. Profilin IIb appears to be a minor form, and its expression is restricted to a limited number of tissues, indicating that the alternative splicing is tightly regulated. Western blotting and whole-mount in situ hybridization show that, in contrast to the expression of profilin I, the expression level of profilin IIa is developmentally regulated. In situ hybridization of adult brain sections reveals overlapping expression patterns of profilins I and IIa.

Alternative Splicing↗

PubMed2001

L552S, an alternatively spliced isoform of XAGE-1, is over-expressed in lung adenocarcinoma.

Using a combination of cDNA subtraction and microarray analysis, we report here the identification and characterization of L552S, an over-expressed, alternatively spliced isoform of XAGE-1 in lung adenocarcinoma. Real-time RT-PCR analysis shows that L552S is expressed at levels greater than 10-fold in 12 of 25 lung adenocarcinoma tumors compared with the highest expression level found in all normal tissues tested. L552S is expressed in both early and late stages of lung adenocarcinoma, but it was not detected in large cell carcinoma, small cell carcinoma, or atypical lung neuroendocrine carcinoid. The full-length cDNA for L552S comprises 770 bp and encodes a polypeptide of 160 amino acids. C-terminal 94 amino acids of L552S are identical to a cancer testis antigen, XAGE-1, found in Ewing's sarcoma. Genomic sequence analysis has revealed that L552S and XAGE-1 are alternatively spliced isoforms, and expression of both L552S and XAGE-1 isoforms are present in lung adenocarcinoma. Immunohistochemistry analysis using affinity purified L552S polyclonal antibodies demonstrated specific nuclear staining in 10 of 12 lung adenocarcinoma samples. Furthermore, antibody responses to recombinant L552S protein were observed in seven of 17 lung pleural effusion fluids of lung cancer patients. These results strongly imply that L552S protein is immunogenic and suggest that it might have use as a vaccine target for lung cancer.

Adenocarcinoma↗

PubMed2005

The snoRNA HBII-52 regulates alternative splicing of the serotonin receptor 2C.

The Prader-Willi syndrome is a congenital disease that is caused by the loss of paternal gene expression from a maternally imprinted region on chromosome 15. This region contains a small nucleolar RNA (snoRNA), HBII-52, that exhibits sequence complementarity to the alternatively spliced exon Vb of the serotonin receptor 5-HT(2C)R. We found that HBII-52 regulates alternative splicing of 5-HT(2C)R by binding to a silencing element in exon Vb. Prader-Willi syndrome patients do not express HBII-52. They have different 5-HT(2C)R messenger RNA (mRNA) isoforms than healthy individuals. Our results show that a snoRNA regulates the processing of an mRNA expressed from a gene located on a different chromosome, and the results indicate that a defect in pre-mRNA processing contributes to the Prader-Willi syndrome.

Alternative Splicing↗

PubMed2003

Alternative splicing controls myotonic dystrophy protein kinase structure, enzymatic activity, and subcellular localization.

Transcripts of the myotonic dystrophy protein kinase (DMPK) gene, a member of the Rho kinase family, are subject to cell-type specific alternative splicing. An imbalance in the splice isoform profile of DMPK may play a role in the pathogenesis of DM1, a severe multisystemic disorder. Here, we report how structural subdomains determine biochemical properties and subcellular distribution of DMPK isoforms. A newly developed kinase assay revealed that DMPK is a Lys/Arg-directed kinase. Individual DMPK isoforms displayed comparable transphosphorylation activity and sequence preference for peptide substrates. However, DMPK autophosphorylation and phosphorylation of MYPT1 (as putative in vivo target of DMPK), were dependent on presence of an alternatively spliced VSGGG motif and the nature of the C terminus. In-gel effects of the VSGGG motif on the migration behavior of full-length kinase provide evidence for a model in which this motif mediates 3-D-conformational changes in DMPK isoforms. Finally, different C termini endow DMPK with the ability to bind to either endoplasmic reticulum or mitochondria or to adopt a cytosolic location. Our results suggest that DMPK isoforms have cell-type and location dependent substrate specificities with a role in organellar and cytoarchitectural dynamics.

Alternative Splicing↗

PubMed1992

The alternative splicing of the CD45 tyrosine phosphatase is controlled by negative regulatory trans-acting splicing factors.

CD45, a receptor-type protein tyrosine phosphatase involved in lymphocyte activation, consists of five isoforms generated by alternative mRNA splicing. The pattern of CD45 splicing depends upon cell type, state of activation, and thymic development. We previously showed that mouse B and thymocyte cell lines transfected with a human CD45 minigene construct appropriately splice the alternative exons, demonstrating the presence of trans-acting tissue-specific splicing factors. To study the regulation of CD45 alternative splicing, cells having different splicing patterns were transiently fused, and mRNA was analyzed using reverse transcription-polymerase chain reaction. Human B cells, normally producing only the largest CD45 mRNAs, could splice out the alternative exons after fusion with mouse thymocytes. In contrast, the splicing pattern of human T cell lines (smaller CD45 isoforms) was unaltered by fusion with mouse B cells. This suggests that cells expressing the smallest CD45 isoform contain negatively acting trans-factor(s) that allow the alternative exons to be skipped, and that the full length isoform containing all three alternative exons is the default pattern of splicing. In agreement, incubation of thymocytes or T cell subsets with cycloheximide increased mRNA corresponding to the larger isoforms. CD45 isoform expression can now be interpreted in terms of the presence or absence of negative regulatory trans-acting splicing factors.

Animals↗

PubMed2006

Relative expression of D3 dopamine receptor and alternative splice variant D3nf mRNA in high and low responders to novelty.

Studies in rodents suggest an important role for the D3 dopamine receptor in regulating locomotor responses to spatial novelty and psychostimulants. The D3 receptor alternatively spliced variant D3nf produces a non-dopamine binding protein that may alter D3 receptor localization by dimerizing with the full-length receptor. In the high responder/low responder (HR/LR) model, the locomotor response to an inescapable, novel spatial environment predicts individual differences in the locomotor and rewarding effects of psychostimulants. We hypothesized that individual differences in D3 receptor expression could contribute to individual differences in the locomotor response to novelty in the HR/LR model. To test this hypothesis, we screened rats for response to a novel spatial environment and analyzed brain tissue for mRNA levels of the D3 receptor and D3nf by real-time RT-PCR. The ratios of D3/D3nf mRNA in prefrontal cortex and substantia nigra/ventral tegmentum were significantly lower in HRs than in LRs. There were no differences in relative expression of D3/D3nf between HRs and LRs in nucleus accumbens. These data further support a role for the D3 dopamine receptor in behavioral responses to novelty and, given the established relationship between novelty and psychostimulant responses, suggest that the D3 receptor may be an important target for assessment of drug abuse vulnerability. Additionally, these findings are consistent with the hypothesis that alternative splicing may contribute to regulation of D3 dopamine receptor function.

Alternative Splicing↗

PubMed1994

An exon 28 mutation resulting in alternative splicing of the glycoprotein IIb transcript and Glanzmann's thrombasthenia.

The alternatively spliced from mRNA of platelet glycoprotein IIb (GPIIb) with a deletion of exon 28 (GPIIb-28) has been isolated from the HEL cell cDNA library. The defective expression on the surface of DNA cotransfected COS-1 cells with GPIIb-28 and GPIIIa cDNAs was described in an earlier report. We studied siblings with Glanzmann's thrombasthenia who expressed only the GPIIb-28 mRNA in their platelets. Flow cytometry showed that the patients' platelets failed to bind GPIIb/IIIa complex-specific and GPIIb-specific monoclonal antibody. Western blotting showed that the patients' platelets had defective GPIIb and have trace amounts of GPIIIa. Sequence analysis was performed after polymerase chain amplification of the patients' GPIIb and GPIIIa mRNAs. The patients' GPIIb cDNA had a deletion of the exon 28 nucleotides. The polymerase chain reaction (PCR) from exon 27 to 29 showed that the GPIIb-28 mRNA was 3% +/- 1.6% of the normally, spliced form in control platelets, and 61% in the megakaryoblastic cell line UT-7. The patients' platelets showed only the GPIIb-28. Family study and quantitative PCR studies showed that these patients were compound heterozygotes of two GPIIb gene defects. The father's allele is described in this report and involves skipping exon 28 secondary to a base substitution at codon Gln948, CAG-->TAG. The mother's allele appears to involve decreasing GPIIb mRNA levels in platelets. Our results indicate that the GPIIb-28 is not expressed on platelet membranes as a stable GPIIb/IIIa heterodimer or left as a monomer in platelets. Our studies confirm the previous data observed in COS-1 cells expressing recombinant GPIIb-28.

Alternative Splicing↗