The cloning, genomic organization and tissue expression profile of the human DLG5 gene

BACKGROUND: Familial atrial fibrillation, an autosomal dominant disease, was previously mapped to chromosome 10q22. One of the genes mapped to the 10q22 region is DLG5, a member of the MAGUKs (Membrane Associated Gyanylate Kinase) family which mediates intracellular signaling. Only a partial cDNA was available for DLG5. To exclude potential disease inducing mutations, it was necessary to obtain a complete cDNA and genomic sequence of the gene. METHODS: The Northern Blot analysis performed using 3' UTR of this gene indicated the transcript size to be about 7.2 KB. Using race technique and library screening the entire cDNA was cloned. This gene was evaluated by sequencing the coding region and splice functions in normal and affected family members with familial atrial fibrillation. Furthermore, haploid cell lines from affected patients were generated and analyzed for deletions that may have been missed by PCR. RESULTS: We identified two distinct alternately spliced transcripts of this gene. The genomic sequence of the DLG5 gene spanned 79 KB with 32 exons and was shown to have ubiquitous human tissue expression including placenta, heart, skeletal muscle, liver and pancreas. CONCLUSIONS: The entire cDNA of DLG5 was identified, sequenced and its genomic organization determined

Global analysis of aberrant pre-mRNA splicing in glioblastoma using exon expression arrays

<p>Abstract</p> <p>Background</p> <p>Tumor-predominant splice isoforms were identified during comparative <it>in silico </it>sequence analysis of EST clones, suggesting that global aberrant alternative pre-mRNA splicing may be an epigenetic phenomenon in cancer. We used an exon expression array to perform an objective, genome-wide survey of glioma-specific splicing in 24 GBM and 12 nontumor brain samples. Validation studies were performed using RT-PCR on glioma cell lines, patient tumor and nontumor brain samples.</p> <p>Results</p> <p>In total, we confirmed 14 genes with glioma-specific splicing; seven were novel events identified by the exon expression array (<it>A2BP1, BCAS1, CACNA1G, CLTA, KCNC2, SNCB</it>, and <it>TPD52L2</it>). Our data indicate that large changes (> 5-fold) in alternative splicing are infrequent in gliomagenesis (< 3% of interrogated RefSeq entries). The lack of splicing changes may derive from the small number of splicing factors observed to be aberrantly expressed.</p> <p>Conclusion</p> <p>While we observed some tumor-specific alternative splicing, the number of genes showing exclusive tumor-specific isoforms was on the order of tens, rather than the hundreds suggested previously by <it>in silico </it>mining. Given the important role of alternative splicing in neural differentiation, there may be selective pressure to maintain a majority of splicing events in order to retain glial-like characteristics of the tumor cells.</p

Methylation of the candidate biomarker TCF21 is very frequent across a spectrum of early-stage nonsmall cell lung cancers

The transcription factor TCF21 is involved in mesenchymal-to-epithelial differentiation and was shown to be aberrantly hypermethylated in lung and head and neck cancers. Because of its reported high frequency of hypermethylation in lung cancer, we sought to characterize the stages and types of non-small cell lung cancer (NSCLC) that are hypermethylated and to define the frequency of hypermethylation and associated “second hits”

Effects of MDM2, MDM4 and TP53 Codon 72 Polymorphisms on Cancer Risk in a Cohort Study of Carriers of TP53 Germline Mutations

Previous studies have shown that MDM2 SNP309 and p53 codon 72 have modifier effects on germline P53 mutations, but those studies relied on case-only studies with small sample sizes. The impact of MDM4 polymorphism on tumor onset in germline mutation carriers has not previously been studied.We analyzed 213 p53 germline mutation carriers including 168(78.9%) affected with cancer and 174 who had genotypic data. We analyzed time to first cancer using Kaplan-Meier and Cox proportional hazards methods, comparing risks according to polymorphism genotypes. For MDM2 SNP309, a significant difference of 9.0 years in the average age of cancer diagnosis was observed between GG/GT and TT carriers (18.6 versus 27.6 years, P = 0.0087). The hazards ratio was 1.58 (P = 0.03) comparing risks among individuals with GG/GT to risk among TT, but this effect was only significant in females (HR = 1.60, P = 0.02). Compared to other genotypes, P53 codon 72 PP homozygotes had a 2.24 times (P = 0.03) higher rate for time to develop cancer. We observed a multiplicative joint effect of MDM2 and p53 codon72 polymorphism on risk. The MDM4 polymorphism had no significant effects.Our results suggest that the MDM2 SNP309 G allele is associated with cancer risk in p53 germline mutation carriers and accelerates time to cancer onset with a pronounced effect in females. A multiplicative joint effect exists between the MDM2 SNP309 G allele and the p53 codon 72 G allele in the risk of cancer development. Our results further define cancer risk in carriers of germline p53 mutations

Chromosomal organization and evolutionary conservation of the human chromosome 19q linkage group containing three DNA repair genes

A series of human-rodent somatic cell hybrids were investigated by Southern blot analysis for the presence or absence of twenty-six molecular markers and three isozyme loci from human chromosome 19. Based on the co-retention of these markers in the various independent hybrid clones containing portions of human chromosome 19 and on pulsed field mapping, chromosome 19 is divided into twenty ordered regions. The most likely marker order for the chromosome is: (LDLR, C3)-(cen-MANNB)-D19S7-PEPD-D19S9-GPI-TGF$\beta$-(CYP2A, NCA, CGM2, BCKAD)-PSG1a-(D19S8, XRCC1)-(D19S19, ATP1A3)-(D19S37, APOC2)-CKMM-ERCC2-ERCC1-(D19S62, D19S51)-D19S6-D19S50-D19S22-(CGB, FTL)-qter. The region of 19q between the proximal marker D19S7 and the distal gene coding for the beta subunit of chorionic gonadotropin (CGB) is about 37 Mb in size and covers about 37 cM genetic distance. The ration of genetic to physical distance on 19q is therefore very close to the genomic average OF 1 cM/Mb. Estimates of physical distances for intervals between chromosome 19 markers were calculated using a mapping function which estimates distances based on the number of breaks in hybrid clone panels. The consensus genetic distances between individual markers (established at HBM10) were compared to these estimates of physical distances. The close agreement between the two estimates suggested that spontaneously broken hybrids are as appropriate for this type of study as radiation hybrids. All three DNA repair genes located on chromosome 19 were found to have homologues on Chinese hamster chromosome 9, which is hemizygous in CHO cells, providing an explanation for the apparent ease with which mutations at these loci were identified in CHO cells. Homologues of CKMM and TGF$\beta$ (from human chromosome 19q) and a mini-satellite DNA specific to the distal region of human chromosome 19q were also mapped to Chinese hamster 9. Markers from 19p did not map to this hamster chromosome. Thus the q-arm of chromosome 19, at least between the genes PEPD and ERCC1, appears to be a linkage group which is conserved intact between humans and Chinese hamsters

Molecular signatures of metastasis in head and neck cancer

Background: Metastases are the primary cause of cancer treatment failure and death, yet metastatic mechanisms remain incompletely understood. Methods: We studied the molecular basis of head and neck cancer metastasis by transcriptionally profiling 70 samples from 27 patients-matching normal adjacent tissue, primary tumor, and cervical lymph node metastases. Results: We identified tumor-associated expression signatures common to both primary tumors and metastases. Use of matching metastases revealed an additional 46 dysregulated genes associated solely with head and neck cancer metastasis. However, despite being metastasis-specific in our sample set, these 46 genes are concordant with genes previously discovered in primary tumors that metastasized. Conclusions: Although our data and related studies show that most of the metastatic potential appears to be inherent to the primary tumor, they are also consistent with the notion that a limited number of additional clonal changes are necessary to yield the final metastatic cell(s), albeit in a variable temporal order

A long-range restriction map of the human chromosome 19q13 region: Close physical linkage between CKMM and the ERCC1 and ERCC2 genes

We report on the physical ordering of genes in a relatively small area of chromosome 19, segment q13, containing the locus for myotonic dystrophy (DM), the most frequent heritable muscular dystrophy of adulthood in man. DNAs from somatic cell hybrids with der 19q products that carry a breakpoint across the muscle-specific creatine kinase (CKMM) gene were analyzed by Southern blotting using probes for CKMM, APOC2, and the repair genes ERCC1 and ERCC2. Results were combined with data from CHEF and field inversion-gel-electrophoresis separation of large-sized DNA restriction fragments to establish a map localizing both DNA-repair genes and the CKMM gene within the same 250 kb of DNA, the order being cen–CKMM–ERCC2–ERCC1–ter, with APOC2 being at more than 260 kb proximal to CKMM. Transcriptional start sites of the CKMM and DNA-repair genes are all on the telomeric side of the genes. Our results provide a framework for the construction of a larger physical map of the area, which will facilitate the search for the DM gene

Mutant (CCTG)n Expansion Causes Abnormal Expression of Zinc Finger Protein 9 (ZNF9) in Myotonic Dystrophy Type 2

The mutation that underlies myotonic dystrophy type 2 (DM2) is a (CCTG)n expansion in intron 1 of zinc finger protein 9 (ZNF9). It has been suggested that ZNF9 is of no consequence for disease pathogenesis. We determined the expression levels of ZNF9 during muscle cell differentiation and in DM2 muscle by microarray profiling, real-time RT-PCR, splice variant analysis, immunofluorescence, and Western blotting. Our results show that in differentiating myoblasts, ZNF9 protein was localized primarily to the nucleus, whereas in mature muscle fibers, it was cytoplasmic and organized in sarcomeric striations at the Z-disk. In patients with DM2, ZNF9 was abnormally expressed. First, there was an overall reduction in both the mRNA and protein levels. Second, the subcellular localization of the ZNF9 protein was somewhat less cytoplasmic and more membrane-bound. Third, our splice variant analysis revealed retention of intron 3 in an aberrant isoform, and fourth quantitative allele-specific expression analysis showed the persistence of intron 1 sequences from the abnormal allele, further suggesting that the mutant allele is incompletely spliced. Thus, the decrease in total expression appears to be due to impaired splicing of the mutant transcript. Our data indicate that ZNF9 expression in DM2 patients is altered at multiple levels. Although toxic RNA effects likely explain overlapping phenotypic manifestations between DM1 and DM2, abnormal ZNF9 levels in DM2 may account for the differences in DM1