Selective Regulation of Agrin mRNA Induction and Alternative Splicing in PC12 Cells by Ras-dependent Actions of Nerve Growth Factor

Smith, Martin A.; Fanger, Gary R.; O'Connor, Lawrence T.; Bridle, Patricia; Maue, Robert A.

doi:10.1074/jbc.272.25.15675

Cited by 30 publications

(19 citation statements)

References 66 publications

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“…One of the surprising findings in this study is that at least 24 h are needed from the time of activation to the detection of a significant change in CD45 mRNA expression. This is consistent with the observation that a significant change in CD45 surface expression first occurs 2 to 3 days following stimulation (2,5,40) and with the time course observed for at least one other signaling-induced alternative splicing event (51). However, many other changes in gene expression, such as induction of interleukin-2 transcription and alternative splicing of CD44 (see below for further discussion), are observed within 6 to 7 h of T-cell activation.…”

Section: Discussionsupporting

confidence: 87%

“…Frequently, alternative splicing is regulated in a tissue-or developmental stage-specific fashion through the activity of tissue-specific factors (17,60). In addition, there have been several documented examples of exon inclusion being regulated in response to extracellular stimuli, including stimulation of the T-cell receptor (TCR) (10,21,47,51,61,65). However, the mechanisms by which such signaling events can influence premRNA splicing are largely unexplored.…”

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confidence: 99%

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A Model System for Activation-Induced Alternative Splicing of CD45 Pre-mRNA in T Cells Implicates Protein Kinase C and Ras

Lynch

Weiss

2000

Molecular and Cellular Biology

128

142

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Multiple isoforms of the protein tyrosine phosphatase CD45 are expressed on the surface of human T cells. Interestingly, the expression of these isoforms has been shown to vary significantly upon T-cell activation. In this report, we describe a novel cell line-based model system in which we can mimic the activation-induced alternative splicing of CD45 observed in primary T cells. Of the many proximal signaling events induced by T-cell stimulation, we show that activation of protein kinase C and activation of Ras are important for the switch toward the exclusion of CD45 variable exons, whereas events related to Ca 2؉ flux are not. In addition, the ability of cycloheximide to block the activation-induced alternative splicing of CD45 suggests a requirement for de novo protein synthesis. We further demonstrate that sequences which have previously been implicated in the tissue-specific regulation of CD45 variable exons are likewise necessary and sufficient for activationinduced splicing. These results provide an initial understanding of the requirements for CD45 alternative splicing upon T-cell activation, and they confirm the importance of this novel cell line in facilitating a more detailed analysis of the activation-induced regulation of CD45 than has been previously possible.Alternative pre-mRNA splicing is a process by which multiple functionally distinct proteins may be encoded from a single gene through the variable inclusion of individual exons. In general, variable exon inclusion is regulated by proteins which bind to sequences within the regulated gene and influence the recognition of splice sites by the basic splicing machinery, or spliceosome (for recent reviews, see references 1, 4, 6, and 18). Frequently, alternative splicing is regulated in a tissue-or developmental stage-specific fashion through the activity of tissue-specific factors (17, 60). In addition, there have been several documented examples of exon inclusion being regulated in response to extracellular stimuli, including stimulation of the T-cell receptor (TCR) (10,21,47,51,61,65). However, the mechanisms by which such signaling events can influence premRNA splicing are largely unexplored.Engagement of the TCR by ligand initiates a signal transduction cascade within the T cell which ultimately results in a number of morphological and functional changes in the cell (11,62). One such change is a dramatic alteration in the cell surface expression of isoforms of the transmembrane protein tyrosine phosphatase CD45 (for reviews see references 57 and 58). The gene encoding CD45 encompasses 33 exons. Most of these exons, including those which encode the intracellular phosphatase domains, are constitutively included in the mature mRNA. However, three of the exons which encode part of the extracellular domain (exons 4, 5, and 6) are variably excluded from the mRNA. The peptide sequences encoded by the CD45 variable exons are rich in O-linked glycosylation sites; thus, a change in inclusion of these exons from the mRNA results in a dramatic change in t...

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Section: Discussionsupporting

confidence: 87%

mentioning

confidence: 99%

A Model System for Activation-Induced Alternative Splicing of CD45 Pre-mRNA in T Cells Implicates Protein Kinase C and Ras

Lynch

Weiss

2000

Molecular and Cellular Biology

128

142

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“…Several transcriptional inductions and alternative splicings triggered by NGF stimulation followed by Ras activation in PC12 cells have been demonstrated (35). However, the specific mechanisms of these alternative splicings linked to the neurite outgrowth have not been studied precisely.…”

Section: Discussionmentioning

confidence: 99%

Neurofibromatosis Type I Tumor Suppressor Neurofibromin Regulates Neuronal Differentiation via Its GTPase-activating Protein Function toward Ras

Yunoue

Tokuo

Fukunaga

et al. 2003

Journal of Biological Chemistry

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Neurofibromin, the neurofibromatosis type 1 (NF1) gene product, contains a central domain homologous to a family of proteins known as Ras-GTPase-activating proteins (Ras-GAPs), which function as negative regulators of Ras. The loss of neurofibromin function has been thought to be implicated in the abnormal regulation of Ras in NF1-related pathogenesis. In this study, we found a novel role of neurofibromin in neuronal differentiation in conjunction with the regulation of Ras activity via its GAP-related domain (GRD) in neuronal cells. In PC12 cells, time-dependent increases in the GAP activity of cellular neurofibromin (NF1-GAP) were detected after NGF stimulation, which were correlated with the down-regulation of Ras activity during neurite elongation. Interestingly, the NF1-GAP increase was due to the induction of alternative splicing of NF1-GRD type I triggered by the NGF-induced Ras activation. Dominantnegative (DN) forms of NF1-GRD type I significantly inhibited the neurite extension of PC12 cells via regulation of the Ras state. NF1-GRD-DN also reduced axonal and dendritic branching/extension of rat embryonic hippocampal neurons. These results demonstrate that the mutual regulation of Ras and NF1-GAP is essential for normal neuronal differentiation and that abnormal regulation in neuronal cells may be implicated in NF1-related learning and memory disturbance. Neurofibromatosis type 1 (NF1)1 is one of the most common autosomal dominantly inherited disorders, with an incidence of about 1 in 3500 individuals (1). The NF1 hallmark is the development of benign tumors of the peripheral nervous system and the increased risk of developing malignancies. The NF1 phenotype is highly variable; it affects several organ systems, including bones, skin, irises, and central nervous system manifested as gliomas and learning disabilities. The NF1 gene lies on chromosome 17q11.2 and encodes neurofibromin, a large 2818-amino acid protein (2). Since the majority of NF1 gene mutations frequently found in NF1 patients prevent intact neurofibromin expression, functional disruption of neurofibromin is potentially relevant to the expression of some or all of the multiple abnormalities that occur in NF1 patients (3).A region centered around the 360 amino acids encoded by the NF1 gene shows significant homology to the known catalytic domains of mammalian Ras GTPase-activating protein (p120GAP) and is also similar to yeast IRA1/2 proteins, which interact with Ras and mediate hydrolysis of Ras-bound GTP to GDP, resulting in Ras protein inactivation. The GAP-related domain of the NF1 gene product (NF1-GRD) also stimulates Ras GTPase and consequently inactivates Ras protein (4, 5).Two different isoforms, type I and type II, which are formed by alternative splicing, have been identified in the NF1-GRD region. Type II contains an additional 63-bp insertion (exon 23a) that encodes 21 amino acids in the center of NF1-GRD type I (6). The specific expression patterns of the two isoforms have been studied in several organs and cells (7,8) and pro...

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“…The delayed response genes are transcriptionally active hours to days following NGF treatment (6,7), and the induction of several genes, such as agrin, tau, transin, and SCG10, has been shown to be Ras-dependent (8,10,11). Furthermore, transcriptional down-regulation of the epidermal growth factor receptor requires Ras activity (36).…”

Section: Resultsmentioning

confidence: 99%

Adenosine A2A Receptor mRNA Regulation by Nerve Growth Factor Is TrkA-, Src-, and Ras-dependent via Extracellular Regulated Kinase and Stress-activated Protein Kinase/c-Jun NH2-terminal Kinase

Malek¹,

Nie²,

Ramkumar³

et al. 1999

Journal of Biological Chemistry

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Selective Regulation of Agrin mRNA Induction and Alternative Splicing in PC12 Cells by Ras-dependent Actions of Nerve Growth Factor

Cited by 30 publications

References 66 publications

A Model System for Activation-Induced Alternative Splicing of CD45 Pre-mRNA in T Cells Implicates Protein Kinase C and Ras

A Model System for Activation-Induced Alternative Splicing of CD45 Pre-mRNA in T Cells Implicates Protein Kinase C and Ras

Neurofibromatosis Type I Tumor Suppressor Neurofibromin Regulates Neuronal Differentiation via Its GTPase-activating Protein Function toward Ras

Adenosine A2A Receptor mRNA Regulation by Nerve Growth Factor Is TrkA-, Src-, and Ras-dependent via Extracellular Regulated Kinase and Stress-activated Protein Kinase/c-Jun NH2-terminal Kinase

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