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Transcript- and tissue-specific imprinting of a tumour suppressor gene.

Schulz R, McCole RB, Woodfine K, Wood AJ, Chahal M, Monk D, Moore GE, Oakey RJ - Hum. Mol. Genet. (2008)

Bottom Line: We propose that the tissue-specific imprinting of Blcap is due to the particularly high transcriptional activity of Nnat in brain, as has been suggested previously for the similarly organized and imprinted murine Commd1/U2af1-rs1 locus.For Commd1/U2af1-rs1, we show that it too produces distinct transcript variants with reciprocal allele-specific expression.The imprinted expression of BLCAP and its interplay with NNAT at the transcriptional level may be relevant to human carcinogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical and Molecular Genetics, King's College London, London SE1 9RT, UK.

ABSTRACT
The Bladder Cancer-Associated Protein gene (BLCAP; previously BC10) is a tumour suppressor that limits cell proliferation and stimulates apoptosis. BLCAP protein or message are downregulated or absent in a variety of human cancers. In mouse and human, the first intron of Blcap/BLCAP contains the distinct Neuronatin (Nnat/NNAT) gene. Nnat is an imprinted gene that is exclusively expressed from the paternally inherited allele. Previous studies found no evidence for imprinting of Blcap in mouse or human. Here we show that Blcap is imprinted in mouse and human brain, but not in other mouse tissues. Moreover, Blcap produces multiple distinct transcripts that exhibit reciprocal allele-specific expression in both mouse and human. We propose that the tissue-specific imprinting of Blcap is due to the particularly high transcriptional activity of Nnat in brain, as has been suggested previously for the similarly organized and imprinted murine Commd1/U2af1-rs1 locus. For Commd1/U2af1-rs1, we show that it too produces distinct transcript variants with reciprocal allele-specific expression. The imprinted expression of BLCAP and its interplay with NNAT at the transcriptional level may be relevant to human carcinogenesis.

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Related in: MedlinePlus

Detection of Blcap_v1a and Blcap_v2a in MatDp(dist2), PatDp(dist2) and non-UpDp (T11H) newborn brain RNA by northern hybridization. The signal obtained with an Actb probe is shown as a loading control (bottom). Left: Hybridization signal produced by the probe designed to the last Blcap exon (N1 in Fig. 1B). A single band was observed in all three lanes where the relative band intensity was highest in the MatDp(dist2) lane and lowest in the PatDp(dist2) lane. Band position and relative intensities were consistent with the known size of the major Blcap transcript Blcap_v1a (2079 bp) and overall preferential expression of Blcap from the maternal allele in newborn brain. Right: Results obtained with a probe specific to the first exon of Blcap_v2a (N2 in Fig. 1B). No band was present in the MatDp(dist2) lane. A single band was visible in the PatDp(dist2) lane. At the corresponding position in the non-UpDp lane, a very faint band was present. This indicates paternal-only expression of Blcap_v2a. The band was slightly shifted upward relative to the band obtained with the N1 probe, as is expected of the slightly larger Blcap_v2a (2258 bp). The exposure times necessary to visualize the results for Blcap_v2a were considerably longer than for the N1 probe, which is consistent with the low abundance of Blcap_v2a relative to Blcap_v1a as determined by qRT–PCR.
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DDN322F4: Detection of Blcap_v1a and Blcap_v2a in MatDp(dist2), PatDp(dist2) and non-UpDp (T11H) newborn brain RNA by northern hybridization. The signal obtained with an Actb probe is shown as a loading control (bottom). Left: Hybridization signal produced by the probe designed to the last Blcap exon (N1 in Fig. 1B). A single band was observed in all three lanes where the relative band intensity was highest in the MatDp(dist2) lane and lowest in the PatDp(dist2) lane. Band position and relative intensities were consistent with the known size of the major Blcap transcript Blcap_v1a (2079 bp) and overall preferential expression of Blcap from the maternal allele in newborn brain. Right: Results obtained with a probe specific to the first exon of Blcap_v2a (N2 in Fig. 1B). No band was present in the MatDp(dist2) lane. A single band was visible in the PatDp(dist2) lane. At the corresponding position in the non-UpDp lane, a very faint band was present. This indicates paternal-only expression of Blcap_v2a. The band was slightly shifted upward relative to the band obtained with the N1 probe, as is expected of the slightly larger Blcap_v2a (2258 bp). The exposure times necessary to visualize the results for Blcap_v2a were considerably longer than for the N1 probe, which is consistent with the low abundance of Blcap_v2a relative to Blcap_v1a as determined by qRT–PCR.

Mentions: Two northern blots with newborn brain RNA of MatDp(dist2), PatDp(dist2) and non-UpDp mice were hybridized with a probe to the last Blcap exon and a probe to the first exon of Blcap_v2a. The former generated a single band in all three lanes (Fig. 4), which corresponds to the known size of Blcap_v1a (2079 bp), the more abundant of the two Blcap transcripts. The lack of additional distinct bands is evidence for the absence of additional major Blcap transcripts. However, the last Blcap exon contributes >87% to the length of the two known transcripts so that additional transcripts with small alternative first exons may have been subsumed in the one band. The band was most intense in the MatDp(dist2) and least intense in the PatDp(dist2) lane, even though the RNA load of the PatDp(dist2) lane was higher (Fig. 4). This indicates that in newborn brain, transcripts sharing the last Blcap exon cumulatively originate most often from the maternal allele, consistent with the microarray measurements in whole newborn head.


Transcript- and tissue-specific imprinting of a tumour suppressor gene.

Schulz R, McCole RB, Woodfine K, Wood AJ, Chahal M, Monk D, Moore GE, Oakey RJ - Hum. Mol. Genet. (2008)

Detection of Blcap_v1a and Blcap_v2a in MatDp(dist2), PatDp(dist2) and non-UpDp (T11H) newborn brain RNA by northern hybridization. The signal obtained with an Actb probe is shown as a loading control (bottom). Left: Hybridization signal produced by the probe designed to the last Blcap exon (N1 in Fig. 1B). A single band was observed in all three lanes where the relative band intensity was highest in the MatDp(dist2) lane and lowest in the PatDp(dist2) lane. Band position and relative intensities were consistent with the known size of the major Blcap transcript Blcap_v1a (2079 bp) and overall preferential expression of Blcap from the maternal allele in newborn brain. Right: Results obtained with a probe specific to the first exon of Blcap_v2a (N2 in Fig. 1B). No band was present in the MatDp(dist2) lane. A single band was visible in the PatDp(dist2) lane. At the corresponding position in the non-UpDp lane, a very faint band was present. This indicates paternal-only expression of Blcap_v2a. The band was slightly shifted upward relative to the band obtained with the N1 probe, as is expected of the slightly larger Blcap_v2a (2258 bp). The exposure times necessary to visualize the results for Blcap_v2a were considerably longer than for the N1 probe, which is consistent with the low abundance of Blcap_v2a relative to Blcap_v1a as determined by qRT–PCR.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2666296&req=5

DDN322F4: Detection of Blcap_v1a and Blcap_v2a in MatDp(dist2), PatDp(dist2) and non-UpDp (T11H) newborn brain RNA by northern hybridization. The signal obtained with an Actb probe is shown as a loading control (bottom). Left: Hybridization signal produced by the probe designed to the last Blcap exon (N1 in Fig. 1B). A single band was observed in all three lanes where the relative band intensity was highest in the MatDp(dist2) lane and lowest in the PatDp(dist2) lane. Band position and relative intensities were consistent with the known size of the major Blcap transcript Blcap_v1a (2079 bp) and overall preferential expression of Blcap from the maternal allele in newborn brain. Right: Results obtained with a probe specific to the first exon of Blcap_v2a (N2 in Fig. 1B). No band was present in the MatDp(dist2) lane. A single band was visible in the PatDp(dist2) lane. At the corresponding position in the non-UpDp lane, a very faint band was present. This indicates paternal-only expression of Blcap_v2a. The band was slightly shifted upward relative to the band obtained with the N1 probe, as is expected of the slightly larger Blcap_v2a (2258 bp). The exposure times necessary to visualize the results for Blcap_v2a were considerably longer than for the N1 probe, which is consistent with the low abundance of Blcap_v2a relative to Blcap_v1a as determined by qRT–PCR.
Mentions: Two northern blots with newborn brain RNA of MatDp(dist2), PatDp(dist2) and non-UpDp mice were hybridized with a probe to the last Blcap exon and a probe to the first exon of Blcap_v2a. The former generated a single band in all three lanes (Fig. 4), which corresponds to the known size of Blcap_v1a (2079 bp), the more abundant of the two Blcap transcripts. The lack of additional distinct bands is evidence for the absence of additional major Blcap transcripts. However, the last Blcap exon contributes >87% to the length of the two known transcripts so that additional transcripts with small alternative first exons may have been subsumed in the one band. The band was most intense in the MatDp(dist2) and least intense in the PatDp(dist2) lane, even though the RNA load of the PatDp(dist2) lane was higher (Fig. 4). This indicates that in newborn brain, transcripts sharing the last Blcap exon cumulatively originate most often from the maternal allele, consistent with the microarray measurements in whole newborn head.

Bottom Line: We propose that the tissue-specific imprinting of Blcap is due to the particularly high transcriptional activity of Nnat in brain, as has been suggested previously for the similarly organized and imprinted murine Commd1/U2af1-rs1 locus.For Commd1/U2af1-rs1, we show that it too produces distinct transcript variants with reciprocal allele-specific expression.The imprinted expression of BLCAP and its interplay with NNAT at the transcriptional level may be relevant to human carcinogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical and Molecular Genetics, King's College London, London SE1 9RT, UK.

ABSTRACT
The Bladder Cancer-Associated Protein gene (BLCAP; previously BC10) is a tumour suppressor that limits cell proliferation and stimulates apoptosis. BLCAP protein or message are downregulated or absent in a variety of human cancers. In mouse and human, the first intron of Blcap/BLCAP contains the distinct Neuronatin (Nnat/NNAT) gene. Nnat is an imprinted gene that is exclusively expressed from the paternally inherited allele. Previous studies found no evidence for imprinting of Blcap in mouse or human. Here we show that Blcap is imprinted in mouse and human brain, but not in other mouse tissues. Moreover, Blcap produces multiple distinct transcripts that exhibit reciprocal allele-specific expression in both mouse and human. We propose that the tissue-specific imprinting of Blcap is due to the particularly high transcriptional activity of Nnat in brain, as has been suggested previously for the similarly organized and imprinted murine Commd1/U2af1-rs1 locus. For Commd1/U2af1-rs1, we show that it too produces distinct transcript variants with reciprocal allele-specific expression. The imprinted expression of BLCAP and its interplay with NNAT at the transcriptional level may be relevant to human carcinogenesis.

Show MeSH
Related in: MedlinePlus