Kim Moran-jones | University of Glasgow (original) (raw)

Papers by Kim Moran-jones

Research paper thumbnail of INC280, an orally available small molecule inhibitor of c-MET, reduces migration and adhesion in ovarian cancer cell models

Scientific reports, 2015

5-year survival rates for ovarian cancer are approximately 40%, and for women diagnosed at late s... more 5-year survival rates for ovarian cancer are approximately 40%, and for women diagnosed at late stage (the majority), just 27%. This indicates a dire need for new treatments to improve survival rates. Recent molecular characterization has greatly improved our understanding of the disease and allowed the identification of potential new targets. One such pathway of interest is the HGF/c-MET axis. Activation of the HGF/c-MET axis has been demonstrated in certain ovarian tumours, and been found to be associated with decreased overall survival, suggesting its potential as a therapeutic target. The objective of this study was to determine the efficacy of a novel, highly potent, orally-bioavailable c-MET inhibitor, INC280, in blocking cell phenotypes important in ovarian cancer metastasis. Using in vitro and ex vivo models, we demonstrate that INC280 inhibits HGF-induced c-MET, and reduces downstream signalling. HGF-stimulated chemotactic and random migration are decreased by INC280 treatm...

Research paper thumbnail of hnRNPs A2 and A3: nucleic acid interactions

Research paper thumbnail of The roles of heterogeneous nuclear ribonucleoproteins A2 and A3 in telomere biogenesis

Research paper thumbnail of b1 integrin deletion enhances progression of prostate cancer in the TRAMP mouse model

Research paper thumbnail of FAK deletion promotes p53-mediated induction of p21, DNA-damage responses and radio-resistance in advanced squamous cancer cells

PLoS ONE, 2011

Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase that is elevated in a variety of hum... more Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase that is elevated in a variety of human cancers. While FAK is implicated in many cellular processes that are perturbed in cancer, including proliferation, actin and adhesion dynamics, polarisation and invasion, there is only some limited information regarding the role of FAK in radiation survival. We have evaluated whether FAK is a general radio-sensitising target, as has been suggested by previous reports. We used a clean genetic system in which FAK was deleted from mouse squamous cell carcinoma (SCC) cells (FAK 2/2), and reconstituted with exogenous FAK wild type (wt). Surprisingly, the absence of FAK was associated with increased radio-resistance in advanced SCC cells. FAK re-expression inhibited p53-mediated transcriptional up-regulation of p21, and a sub-set of other p53 target genes involved in DNA repair, after treatment with ionizing radiation. Moreover, p21 depletion promoted radiosensitisation, implying that FAK-mediated inhibition of p21 induction is responsible for the relative radio-sensitivity of FAKproficient SCC cells. Our work adds to a growing body of evidence that there is a close functional relationship between integrin/FAK signalling and the p53/p21 pathway, but demonstrates that FAK's role in survival after stress is contextdependent, at least in cancer cells. We suggest that there should be caution when considering inhibiting FAK in combination with radiation, as this may not always be clinically advantageous.

Research paper thumbnail of β1 integrin deletion enhances progression of prostate cancer in the TRAMP mouse model

Scientific Reports, 2012

β1 integrin regulates the response of both normal and cancer cells to their local environment. Al... more β1 integrin regulates the response of both normal and cancer cells to their local environment. Although mis-localised in prostate cancer, the role β1 integrin plays in prostate development and carcinogenesis remains unknown. To assess the role of β1 integrin in vivo, we conditionally deleted β1 integrin from prostate epithelium and subsequently crossed these mice to the TRAMP prostate carcinogenesis model. Deletion of β1 integrin following castration and subsequent androgen supplementation resulted in an expansion of the p63-positive basal cell population and decreased differentiation. Consistent with these findings, deletion of β1 integrin in TRAMP mice decreased animal survival, decreased retention of normal prostate morphology, increased the percentage of tissue with poorly differentiated carcinoma, and increased cell proliferation. This study demonstrates that β1 integrin regulates several aspects of normal prostate development and in contrast to its role in several other tissues, its loss is associated with increased rates of prostate tumour progression.

Research paper thumbnail of ZNF300P1 Encodes a lincRNA that regulates cell polarity and is epigenetically silenced in type II epithelial ovarian cancer

Molecular Cancer, 2014

Background: We previously identified that the CpG island-associated promoter of the novel lincRNA... more Background: We previously identified that the CpG island-associated promoter of the novel lincRNA ZNF300P1 (also known as LOC134466) is frequently hypermethylated and silenced in ovarian cancer tissues. However, the function of ZNF300P1 was unknown. In this report we demonstrate that ZNF300P1 is involved in the regulation of key cell cycle and cell motility networks in human ovarian surface epithelial cells, and may play a role in promoting metastasis in ovarian cancer cells. Methods: We applied methylated DNA immunoprecipitation on whole genome promoter tiling arrays and Sequenom assays to examine methylation status of ZNF300P1 in multiple ovarian cancer cell lines, as well as in normal ovarian and ovarian tumor tissues. Transcript profiling was used to investigate the effects of ZNF300P1 suppression in ovarian cancer cells. We utilized siRNA knockdown in normal ovarian surface epithelial cells and performed cellular proliferation, migration and adhesion assays to validate and explore the profiling results. Results: We demonstrate that ZNF300P1 is methylated in multiple ovarian cancer cell lines. Loss of ZNF300P1 results in decreased cell proliferation and colony formation. In addition, knockdown of the ZNF300P1 transcript results in aberrant and less persistent migration in wound healing assays due to a loss of cellular polarity. Using an ex vivo peritoneal adhesion assay, we also reveal a role for ZNF300P1 in the attachment of ovarian cancer cells to peritoneal membranes, indicating a potential function of ZNF300P1 expression in metastasis of ovarian cancer cells to sites within the peritoneal cavity. Conclusion: Our findings further support ZNF300P1 as frequently methylated in ovarian cancer and reveal a novel function for ZNF300P1 lincRNA expression in regulating cell polarity, motility, and adhesion and loss of expression may contribute to the metastatic potential of ovarian cancer cells.

Research paper thumbnail of In vitro properties of hnRNP A2: A role in telomere protection and telomerase recruitment

Research paper thumbnail of Abstract B58: Connective tissue growth factor (CTGF) as a novel therapeutic target in high grade serous ovarian cancer

Clinical Cancer Research, 2013

Research paper thumbnail of In vitro properties of hnRNP A2: A role i telonere protection and telomerase recruitment

Research paper thumbnail of hnRNP A3, A novel RNA cytoplasmic trafficking response element binding protein

Research paper thumbnail of Binding of an RNA trafficking response element to heterogeneous nuclear ribonucleoproteins A1 and A2

Journal of Biological Chemistry, 2000

Heterogeneous nuclear ribonucleoprotein (hnRNP) A2 binds a 21-nucleotide myelin basic protein mRN... more Heterogeneous nuclear ribonucleoprotein (hnRNP) A2 binds a 21-nucleotide myelin basic protein mRNA response element, the A2RE, and A2RE-like sequences in other localized mRNAs, and is a trans-acting factor in oligodendrocyte cytoplasmic RNA trafficking. Recombinant human hnRNPs A1 and A2 were used in a biosensor to explore interactions with A2RE and the cognate oligodeoxyribonucleotide. Both proteins have a single site that bound oligonucleotides with markedly different sequences but did not bind in the presence of heparin. Both also possess a second, specific site that bound only A2RE and was unaffected by heparin. hnRNP A2 bound A2RE in the latter site with a K(d) near 50 nm, whereas the K(d) for hnRNP A1 was above 10 microm. UV cross-linking assays led to a similar conclusion. Mutant A2RE sequences, that in earlier qualitative studies appeared not to bind hnRNP A2 or support RNA trafficking in oligodendrocytes, had dissociation constants above 5 microm for this protein. The two concatenated RNA recognition motifs (RRMs), but not the individual RRMs, mimicked the binding behavior of hnRNP A2. These data highlight the specificity of the interaction of A2RE with these hnRNPs and suggest that the sequence-specific A2RE-binding site on hnRNP A2 is formed by both RRMs acting in cis.

Research paper thumbnail of VEGFR1 (Flt1) Regulates Rab4 Recycling to Control Fibronectin Polymerization and Endothelial Vessel Branching

Research paper thumbnail of hnRNP A2, a potential ssDNA/RNA molecular adapter at the telomere

Nucleic Acids Research, 2005

The heterogeneous nuclear ribonucleoprotein (hnRNP) A2 is a multi-tasking protein that acts in th... more The heterogeneous nuclear ribonucleoprotein (hnRNP) A2 is a multi-tasking protein that acts in the cytoplasm and nucleus. We have explored the possibility that this protein is associated with telomeres and participates in their maintenance. Rat brain hnRNP A2 was shown to have two nucleic acid binding sites. In the presence of heparin one site binds single-stranded oligodeoxyribonucleotides irrespective of sequence but not the corresponding oligoribonucleotides. Both the hnRNP A2-binding cis-acting element for the cytoplasmic RNA trafficking element, A2RE, and the ssDNA telomere repeat match a consensus sequence for binding to a second sequence-specific site identified by mutational analysis. hnRNP A2 protected the telomeric repeat sequence, but not the complementary sequence, against DNase digestion: the glycine-rich domain was found to be necessary, but not sufficient, for protection. The N-terminal RRM (RNA recognition motif) and tandem RRMs of hnRNP A2 also bind the single-stranded, template-containing segment of telomerase RNA. hnRNP A2 colocalizes with telomeric chromatin in the subset of PML bodies that are a hallmark of ALT cells, reinforcing the evidence for hnRNPs having a role in telomere maintenance. Our results support a model in which hnRNP A2 acts as a molecular adapter between singlestranded telomeric repeats, or telomerase RNA, and another segment of ssDNA.

Research paper thumbnail of Heterogeneous Nuclear Ribonucleoprotein A3, a Novel RNA Trafficking Response Element-binding Protein

Journal of Biological Chemistry, 2002

The cis-acting response element, A2RE, which is sufficient for cytoplasmic mRNA trafficking in ol... more The cis-acting response element, A2RE, which is sufficient for cytoplasmic mRNA trafficking in oligodendrocytes, binds a small group of rat brain proteins. Predominant among these is heterogeneous nuclear ribonucleoprotein (hnRNP) A2, a trans-acting factor for cytoplasmic trafficking of RNAs bearing A2RE-like sequences. We have now identified the other A2RE-binding proteins as hnRNP A1/A1(B), hnRNP B1, and four isoforms of hnRNP A3. The rat and human hnRNP A3 cDNAs have been sequenced, revealing the existence of alternatively spliced mRNAs. In Western blotting, 38-, 39-, 41-, and 41.5-kDa components were all recognized by antibodies against a peptide in the glycine-rich region of hnRNP A3, but only the 41- and 41.5-kDa bands bound antibodies to a 15-residue N-terminal peptide encoded by an alternatively spliced part of exon 1. The identities of these four proteins were verified by Edman sequencing and mass spectral analysis of tryptic fragments generated from electrophoretically separated bands. Sequence-specific binding of bacterially expressed hnRNP A3 to A2RE has been demonstrated by biosensor and UV cross-linking electrophoretic mobility shift assays. Mutational analysis and confocal microscopy data support the hypothesis that the hnRNP A3 isoforms have a role in cytoplasmic trafficking of RNA.

Research paper thumbnail of ?IV tubulin is selectively expressed by oligodendrocytes in the central nervous system

Glia, 2005

Oligodendrocyte differentiation and myelination involve dramatic changes in cell signaling pathwa... more Oligodendrocyte differentiation and myelination involve dramatic changes in cell signaling pathways, gene expression patterns, cell shape, and cytoskeletal organization. In a pilot study investigating CNS angiogenesis, oligodendrocytes were intensely labeled by antisera directed against the C-terminal of Tie-2, a 140-kDa transmembrane receptor for angiopoietin. Immunoprecipitation of rat brain proteins with Tie-2 C-terminal antisera, however, produced a single spot of *55-kDa pI *5 by two-dimensional (2D) electrophoresis, which was identified as b-tubulin by mass spectrometry. Isotype-specific antibodies for b IV tubulin selectively labeled oligodendrocytes. First detected in premyelinating oligodendrocytes, b IV tubulin was abundant in myelinating oligodendrocyte perinuclear cytoplasm and processes extending to and along developing myelin internodes. b IV tubulin-positive MTs were diffusely distributed in oligodendrocyte perinuclear cytoplasm and not organized around the centrosome. b IV tubulin may play a role in establishing the oligodendrocyte MT network, which is essential for the transport of myelin proteins, lipids, and RNA during myelination. V V C 2005 Wiley-Liss, Inc.

Research paper thumbnail of hnRNP A2 Regulates Alternative mRNA Splicing of TP53INP2 to Control Invasive Cell Migration

Cancer Research, 2009

Largely owing to widespread deployment of microarray analysis, many of the transcriptional events... more Largely owing to widespread deployment of microarray analysis, many of the transcriptional events associated with invasive cell migration are becoming clear. However, the transcriptional drives to invasive migration are likely modified by alternative splicing of pre-mRNAs to produce functionally distinct patterns of protein expression. Heterogenous nuclear ribonucleoprotein (hnRNP A2) is a known regulator of alternative splicing that is upregulated in a number of invasive cancer types. Here, we report that although siRNA of hnRNP A2 had little influence on the ability of cells to migrate on plastic surfaces, the splicing regulator was clearly required for cells to move effectively on three-dimensional matrices and to invade into plugs of extracellular matrix proteins. We used exon-tiling microarrays to determine that hnRNP A2 controlled approximately six individual splicing events in a three-dimensional matrix-dependent fashion, one of which influenced invasive migration. Here, we show that alternative splicing of an exon in the 5' untranslated region of a gene termed TP53INP2 is a key event downstream of hnRNP A2 that is necessary for cells to invade the extracellular matrix. Furthermore, we report that the consequences of altered TP53INP2 splicing on invasion are likely mediated via alterations in Golgi complex integrity during migration on three-dimensional matrices.

Research paper thumbnail of c-Myc Regulates RNA Splicing of the A-Raf Kinase and Its Activation of the ERK Pathway

Cancer Research, 2011

A-Raf kinase can inhibit apoptosis by binding to the pro-apoptotic MST2 kinase. This function rel... more A-Raf kinase can inhibit apoptosis by binding to the pro-apoptotic MST2 kinase. This function relies on expression of hnRNP H, which ensures the correct splicing of a-raf mRNA needed to produce full-length A-Raf protein. Here we show that expression of hnRNP H and production of full-length A-Raf is positively controlled by c-Myc. Low c-Myc reduces hnRNP H expression and switches a-raf splicing to produce A-Rafshort, a truncated protein. Importantly, A-Rafshort fails to regulate MST2 but retains the Ras binding domain such that it functions as a dominant negative mutant suppressing Ras activation and transformation. Human colon and head and neck cancers exhibit high hnRNP H and high c-Myc levels resulting in enhanced A-Raf expression and reduced expression of ARafshort. Conversely, in normal cells and tissues where c-Myc and hnRNP H are low, A-Rafshort suppresses ERK activation such that it may act as a safeguard against oncogenic transformation. Our findings offer a new paradigm to understand how c-Myc coordinates diverse cell functions by directly affecting alternate splicing of key signaling compotents. growth factor induced activation of A-Raf. However, A-Raf is a poor MEK kinase with barely measurable catalytic activity, which is due to unique non-conserved amino acid substitutions in the N-region (5). Independent of kinase activity, A-Raf constitutively binds mammalian sterile 20-like kinase (MST2) and suppresses MST2 activation and induced apoptosis (6).

Research paper thumbnail of RNA trafficking and localization

FASEB, 2011

... RNA trafficking and localization. Smith, RW, Shan, J., Moran-Jones, K., Ma, ASW, Hatfield, JT... more ... RNA trafficking and localization. Smith, RW, Shan, J., Moran-Jones, K., Ma, ASW, Hatfield, JT, Barbarese, E. and Carson, JH (2003). RNA trafficking and localization. In: , FASEB. FASEB, Snowmass, Colorado, (Abstract). June, 2003. Document type: Conference Paper. ...

Research paper thumbnail of RNA: STRUCTURE, METABOLISM, AND CATALYSIS-Heterogeneous nuclear ribonucleoprotein A3, a novel RNA trafficking response element-binding protein

Research paper thumbnail of INC280, an orally available small molecule inhibitor of c-MET, reduces migration and adhesion in ovarian cancer cell models

Scientific reports, 2015

5-year survival rates for ovarian cancer are approximately 40%, and for women diagnosed at late s... more 5-year survival rates for ovarian cancer are approximately 40%, and for women diagnosed at late stage (the majority), just 27%. This indicates a dire need for new treatments to improve survival rates. Recent molecular characterization has greatly improved our understanding of the disease and allowed the identification of potential new targets. One such pathway of interest is the HGF/c-MET axis. Activation of the HGF/c-MET axis has been demonstrated in certain ovarian tumours, and been found to be associated with decreased overall survival, suggesting its potential as a therapeutic target. The objective of this study was to determine the efficacy of a novel, highly potent, orally-bioavailable c-MET inhibitor, INC280, in blocking cell phenotypes important in ovarian cancer metastasis. Using in vitro and ex vivo models, we demonstrate that INC280 inhibits HGF-induced c-MET, and reduces downstream signalling. HGF-stimulated chemotactic and random migration are decreased by INC280 treatm...

Research paper thumbnail of hnRNPs A2 and A3: nucleic acid interactions

Research paper thumbnail of The roles of heterogeneous nuclear ribonucleoproteins A2 and A3 in telomere biogenesis

Research paper thumbnail of b1 integrin deletion enhances progression of prostate cancer in the TRAMP mouse model

Research paper thumbnail of FAK deletion promotes p53-mediated induction of p21, DNA-damage responses and radio-resistance in advanced squamous cancer cells

PLoS ONE, 2011

Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase that is elevated in a variety of hum... more Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase that is elevated in a variety of human cancers. While FAK is implicated in many cellular processes that are perturbed in cancer, including proliferation, actin and adhesion dynamics, polarisation and invasion, there is only some limited information regarding the role of FAK in radiation survival. We have evaluated whether FAK is a general radio-sensitising target, as has been suggested by previous reports. We used a clean genetic system in which FAK was deleted from mouse squamous cell carcinoma (SCC) cells (FAK 2/2), and reconstituted with exogenous FAK wild type (wt). Surprisingly, the absence of FAK was associated with increased radio-resistance in advanced SCC cells. FAK re-expression inhibited p53-mediated transcriptional up-regulation of p21, and a sub-set of other p53 target genes involved in DNA repair, after treatment with ionizing radiation. Moreover, p21 depletion promoted radiosensitisation, implying that FAK-mediated inhibition of p21 induction is responsible for the relative radio-sensitivity of FAKproficient SCC cells. Our work adds to a growing body of evidence that there is a close functional relationship between integrin/FAK signalling and the p53/p21 pathway, but demonstrates that FAK's role in survival after stress is contextdependent, at least in cancer cells. We suggest that there should be caution when considering inhibiting FAK in combination with radiation, as this may not always be clinically advantageous.

Research paper thumbnail of β1 integrin deletion enhances progression of prostate cancer in the TRAMP mouse model

Scientific Reports, 2012

β1 integrin regulates the response of both normal and cancer cells to their local environment. Al... more β1 integrin regulates the response of both normal and cancer cells to their local environment. Although mis-localised in prostate cancer, the role β1 integrin plays in prostate development and carcinogenesis remains unknown. To assess the role of β1 integrin in vivo, we conditionally deleted β1 integrin from prostate epithelium and subsequently crossed these mice to the TRAMP prostate carcinogenesis model. Deletion of β1 integrin following castration and subsequent androgen supplementation resulted in an expansion of the p63-positive basal cell population and decreased differentiation. Consistent with these findings, deletion of β1 integrin in TRAMP mice decreased animal survival, decreased retention of normal prostate morphology, increased the percentage of tissue with poorly differentiated carcinoma, and increased cell proliferation. This study demonstrates that β1 integrin regulates several aspects of normal prostate development and in contrast to its role in several other tissues, its loss is associated with increased rates of prostate tumour progression.

Research paper thumbnail of ZNF300P1 Encodes a lincRNA that regulates cell polarity and is epigenetically silenced in type II epithelial ovarian cancer

Molecular Cancer, 2014

Background: We previously identified that the CpG island-associated promoter of the novel lincRNA... more Background: We previously identified that the CpG island-associated promoter of the novel lincRNA ZNF300P1 (also known as LOC134466) is frequently hypermethylated and silenced in ovarian cancer tissues. However, the function of ZNF300P1 was unknown. In this report we demonstrate that ZNF300P1 is involved in the regulation of key cell cycle and cell motility networks in human ovarian surface epithelial cells, and may play a role in promoting metastasis in ovarian cancer cells. Methods: We applied methylated DNA immunoprecipitation on whole genome promoter tiling arrays and Sequenom assays to examine methylation status of ZNF300P1 in multiple ovarian cancer cell lines, as well as in normal ovarian and ovarian tumor tissues. Transcript profiling was used to investigate the effects of ZNF300P1 suppression in ovarian cancer cells. We utilized siRNA knockdown in normal ovarian surface epithelial cells and performed cellular proliferation, migration and adhesion assays to validate and explore the profiling results. Results: We demonstrate that ZNF300P1 is methylated in multiple ovarian cancer cell lines. Loss of ZNF300P1 results in decreased cell proliferation and colony formation. In addition, knockdown of the ZNF300P1 transcript results in aberrant and less persistent migration in wound healing assays due to a loss of cellular polarity. Using an ex vivo peritoneal adhesion assay, we also reveal a role for ZNF300P1 in the attachment of ovarian cancer cells to peritoneal membranes, indicating a potential function of ZNF300P1 expression in metastasis of ovarian cancer cells to sites within the peritoneal cavity. Conclusion: Our findings further support ZNF300P1 as frequently methylated in ovarian cancer and reveal a novel function for ZNF300P1 lincRNA expression in regulating cell polarity, motility, and adhesion and loss of expression may contribute to the metastatic potential of ovarian cancer cells.

Research paper thumbnail of In vitro properties of hnRNP A2: A role in telomere protection and telomerase recruitment

Research paper thumbnail of Abstract B58: Connective tissue growth factor (CTGF) as a novel therapeutic target in high grade serous ovarian cancer

Clinical Cancer Research, 2013

Research paper thumbnail of In vitro properties of hnRNP A2: A role i telonere protection and telomerase recruitment

Research paper thumbnail of hnRNP A3, A novel RNA cytoplasmic trafficking response element binding protein

Research paper thumbnail of Binding of an RNA trafficking response element to heterogeneous nuclear ribonucleoproteins A1 and A2

Journal of Biological Chemistry, 2000

Heterogeneous nuclear ribonucleoprotein (hnRNP) A2 binds a 21-nucleotide myelin basic protein mRN... more Heterogeneous nuclear ribonucleoprotein (hnRNP) A2 binds a 21-nucleotide myelin basic protein mRNA response element, the A2RE, and A2RE-like sequences in other localized mRNAs, and is a trans-acting factor in oligodendrocyte cytoplasmic RNA trafficking. Recombinant human hnRNPs A1 and A2 were used in a biosensor to explore interactions with A2RE and the cognate oligodeoxyribonucleotide. Both proteins have a single site that bound oligonucleotides with markedly different sequences but did not bind in the presence of heparin. Both also possess a second, specific site that bound only A2RE and was unaffected by heparin. hnRNP A2 bound A2RE in the latter site with a K(d) near 50 nm, whereas the K(d) for hnRNP A1 was above 10 microm. UV cross-linking assays led to a similar conclusion. Mutant A2RE sequences, that in earlier qualitative studies appeared not to bind hnRNP A2 or support RNA trafficking in oligodendrocytes, had dissociation constants above 5 microm for this protein. The two concatenated RNA recognition motifs (RRMs), but not the individual RRMs, mimicked the binding behavior of hnRNP A2. These data highlight the specificity of the interaction of A2RE with these hnRNPs and suggest that the sequence-specific A2RE-binding site on hnRNP A2 is formed by both RRMs acting in cis.

Research paper thumbnail of VEGFR1 (Flt1) Regulates Rab4 Recycling to Control Fibronectin Polymerization and Endothelial Vessel Branching

Research paper thumbnail of hnRNP A2, a potential ssDNA/RNA molecular adapter at the telomere

Nucleic Acids Research, 2005

The heterogeneous nuclear ribonucleoprotein (hnRNP) A2 is a multi-tasking protein that acts in th... more The heterogeneous nuclear ribonucleoprotein (hnRNP) A2 is a multi-tasking protein that acts in the cytoplasm and nucleus. We have explored the possibility that this protein is associated with telomeres and participates in their maintenance. Rat brain hnRNP A2 was shown to have two nucleic acid binding sites. In the presence of heparin one site binds single-stranded oligodeoxyribonucleotides irrespective of sequence but not the corresponding oligoribonucleotides. Both the hnRNP A2-binding cis-acting element for the cytoplasmic RNA trafficking element, A2RE, and the ssDNA telomere repeat match a consensus sequence for binding to a second sequence-specific site identified by mutational analysis. hnRNP A2 protected the telomeric repeat sequence, but not the complementary sequence, against DNase digestion: the glycine-rich domain was found to be necessary, but not sufficient, for protection. The N-terminal RRM (RNA recognition motif) and tandem RRMs of hnRNP A2 also bind the single-stranded, template-containing segment of telomerase RNA. hnRNP A2 colocalizes with telomeric chromatin in the subset of PML bodies that are a hallmark of ALT cells, reinforcing the evidence for hnRNPs having a role in telomere maintenance. Our results support a model in which hnRNP A2 acts as a molecular adapter between singlestranded telomeric repeats, or telomerase RNA, and another segment of ssDNA.

Research paper thumbnail of Heterogeneous Nuclear Ribonucleoprotein A3, a Novel RNA Trafficking Response Element-binding Protein

Journal of Biological Chemistry, 2002

The cis-acting response element, A2RE, which is sufficient for cytoplasmic mRNA trafficking in ol... more The cis-acting response element, A2RE, which is sufficient for cytoplasmic mRNA trafficking in oligodendrocytes, binds a small group of rat brain proteins. Predominant among these is heterogeneous nuclear ribonucleoprotein (hnRNP) A2, a trans-acting factor for cytoplasmic trafficking of RNAs bearing A2RE-like sequences. We have now identified the other A2RE-binding proteins as hnRNP A1/A1(B), hnRNP B1, and four isoforms of hnRNP A3. The rat and human hnRNP A3 cDNAs have been sequenced, revealing the existence of alternatively spliced mRNAs. In Western blotting, 38-, 39-, 41-, and 41.5-kDa components were all recognized by antibodies against a peptide in the glycine-rich region of hnRNP A3, but only the 41- and 41.5-kDa bands bound antibodies to a 15-residue N-terminal peptide encoded by an alternatively spliced part of exon 1. The identities of these four proteins were verified by Edman sequencing and mass spectral analysis of tryptic fragments generated from electrophoretically separated bands. Sequence-specific binding of bacterially expressed hnRNP A3 to A2RE has been demonstrated by biosensor and UV cross-linking electrophoretic mobility shift assays. Mutational analysis and confocal microscopy data support the hypothesis that the hnRNP A3 isoforms have a role in cytoplasmic trafficking of RNA.

Research paper thumbnail of ?IV tubulin is selectively expressed by oligodendrocytes in the central nervous system

Glia, 2005

Oligodendrocyte differentiation and myelination involve dramatic changes in cell signaling pathwa... more Oligodendrocyte differentiation and myelination involve dramatic changes in cell signaling pathways, gene expression patterns, cell shape, and cytoskeletal organization. In a pilot study investigating CNS angiogenesis, oligodendrocytes were intensely labeled by antisera directed against the C-terminal of Tie-2, a 140-kDa transmembrane receptor for angiopoietin. Immunoprecipitation of rat brain proteins with Tie-2 C-terminal antisera, however, produced a single spot of *55-kDa pI *5 by two-dimensional (2D) electrophoresis, which was identified as b-tubulin by mass spectrometry. Isotype-specific antibodies for b IV tubulin selectively labeled oligodendrocytes. First detected in premyelinating oligodendrocytes, b IV tubulin was abundant in myelinating oligodendrocyte perinuclear cytoplasm and processes extending to and along developing myelin internodes. b IV tubulin-positive MTs were diffusely distributed in oligodendrocyte perinuclear cytoplasm and not organized around the centrosome. b IV tubulin may play a role in establishing the oligodendrocyte MT network, which is essential for the transport of myelin proteins, lipids, and RNA during myelination. V V C 2005 Wiley-Liss, Inc.

Research paper thumbnail of hnRNP A2 Regulates Alternative mRNA Splicing of TP53INP2 to Control Invasive Cell Migration

Cancer Research, 2009

Largely owing to widespread deployment of microarray analysis, many of the transcriptional events... more Largely owing to widespread deployment of microarray analysis, many of the transcriptional events associated with invasive cell migration are becoming clear. However, the transcriptional drives to invasive migration are likely modified by alternative splicing of pre-mRNAs to produce functionally distinct patterns of protein expression. Heterogenous nuclear ribonucleoprotein (hnRNP A2) is a known regulator of alternative splicing that is upregulated in a number of invasive cancer types. Here, we report that although siRNA of hnRNP A2 had little influence on the ability of cells to migrate on plastic surfaces, the splicing regulator was clearly required for cells to move effectively on three-dimensional matrices and to invade into plugs of extracellular matrix proteins. We used exon-tiling microarrays to determine that hnRNP A2 controlled approximately six individual splicing events in a three-dimensional matrix-dependent fashion, one of which influenced invasive migration. Here, we show that alternative splicing of an exon in the 5' untranslated region of a gene termed TP53INP2 is a key event downstream of hnRNP A2 that is necessary for cells to invade the extracellular matrix. Furthermore, we report that the consequences of altered TP53INP2 splicing on invasion are likely mediated via alterations in Golgi complex integrity during migration on three-dimensional matrices.

Research paper thumbnail of c-Myc Regulates RNA Splicing of the A-Raf Kinase and Its Activation of the ERK Pathway

Cancer Research, 2011

A-Raf kinase can inhibit apoptosis by binding to the pro-apoptotic MST2 kinase. This function rel... more A-Raf kinase can inhibit apoptosis by binding to the pro-apoptotic MST2 kinase. This function relies on expression of hnRNP H, which ensures the correct splicing of a-raf mRNA needed to produce full-length A-Raf protein. Here we show that expression of hnRNP H and production of full-length A-Raf is positively controlled by c-Myc. Low c-Myc reduces hnRNP H expression and switches a-raf splicing to produce A-Rafshort, a truncated protein. Importantly, A-Rafshort fails to regulate MST2 but retains the Ras binding domain such that it functions as a dominant negative mutant suppressing Ras activation and transformation. Human colon and head and neck cancers exhibit high hnRNP H and high c-Myc levels resulting in enhanced A-Raf expression and reduced expression of ARafshort. Conversely, in normal cells and tissues where c-Myc and hnRNP H are low, A-Rafshort suppresses ERK activation such that it may act as a safeguard against oncogenic transformation. Our findings offer a new paradigm to understand how c-Myc coordinates diverse cell functions by directly affecting alternate splicing of key signaling compotents. growth factor induced activation of A-Raf. However, A-Raf is a poor MEK kinase with barely measurable catalytic activity, which is due to unique non-conserved amino acid substitutions in the N-region (5). Independent of kinase activity, A-Raf constitutively binds mammalian sterile 20-like kinase (MST2) and suppresses MST2 activation and induced apoptosis (6).

Research paper thumbnail of RNA trafficking and localization

FASEB, 2011

... RNA trafficking and localization. Smith, RW, Shan, J., Moran-Jones, K., Ma, ASW, Hatfield, JT... more ... RNA trafficking and localization. Smith, RW, Shan, J., Moran-Jones, K., Ma, ASW, Hatfield, JT, Barbarese, E. and Carson, JH (2003). RNA trafficking and localization. In: , FASEB. FASEB, Snowmass, Colorado, (Abstract). June, 2003. Document type: Conference Paper. ...

Research paper thumbnail of RNA: STRUCTURE, METABOLISM, AND CATALYSIS-Heterogeneous nuclear ribonucleoprotein A3, a novel RNA trafficking response element-binding protein