Identification of a colon mucosa gene that is down-regulated in colon adenomas and adenocarcinomas

A cDNA, which we call DRA (for down-regulated in adenoma) has been isolated. Its mRNA is expressed exclusively in normal colon tissue, probably only in the mucosal epithelia. Expression of the DRA gene is significantly decreased in adenomas (polyps) and adenocarcinomas of the colon. The DRA gene appears to be a single-copy gene present on chromosome 7, a chromosome associated with colorectal tumorigenesis. The predicted DRA polypeptide is an 84,500-Da protein that contains charged clusters of amino acids, primarily at the NH2 and COOH termini. Together with potential nuclear targeting motifs, an acidic transcriptional activation domain, and a homeobox domain, these elements suggest a transcription factor or a protein that may interact with transcription factors. Such a function may be consistent with a role in tissue-specific gene expression and/or as a candidate tumor-suppressor gene.

Magnesium bisamides as reagents in synthesis

As part of the continued requirement for more selective reagents in organic synthesis, magnesium bisamides are becoming established as a class of organometallic bases with considerable potential. Their relatively mild reactivity, combined with their high degree of steric congestion, leads to a distinct class of reagents with significantly different chemo-, regio-, stereo- and enantioselectivities when compared with existing species and protocols.

Trimagnesium-bridged trinuclear ferrocenophanes cocomplexed with solvated mononuclear alkali metal amide molecules

Three prototypes of the remarkable new class of compound referred to in the title have been synthesised by treating ferrocene with the same mixed lithium (or sodium)-magnesium amide recipes as those used previously to make s-block metal inverse crowns.

Subtraction hybridization cDNA libraries from colon carcinoma and hepatic cancer

cDNA clones of differentially expressed mRNAs in a colon carcinoma and a hepatocellular carcinoma have been isolated by subtractive cDNA cloning. The subtracted material is at least 90 X enriched for differentially expressed sequences and can be used for construction of subtractive cDNA libraries and polymerase chain reaction (PCR) amplification to generate differential probes. Commercially available lambda ZAP II is used for construction of primary libraries since single-stranded phage bearing the cloned cDNA can be excised in vivo and because lambda libraries are convenient for subsequent screening and manipulations. Rare mRNAs (less than 0.01% abundance), which are differentially expressed, can be isolated utilizing this procedure.

Human DRA functions as a sulfate transporter in Sf9 insect cells

DRA is a gene that is down-regulated in colon adenomas and adenocarcinomas in humans. We have previously shown that DRA proteins are found as various forms in tissue due to differential glycosylation. This study has focused on the function of DRA related to its subcellular localization. We used the baculovirus expression system and overexpressed a nearly full-length DRA driven by a polyhedrin promoter in Sf9 insect cells. DRA protein expressed in this cell was underglycosylated relative to normal colon mucosa, but uniformly targeted to the cell membrane. It also appears to undergo posttranslational cleavage, removing about 100 amino acids from its amino terminus. This membrane localization is similar to what we observed in the colon mucosa. An ion transport assay demonstrated that DRA functions as a sulfate transporter. When DRA was expressed, sulfate import was increased more than threefold compared to the control. Sulfate import was inhibitable by the anion transporter inhibitor, DIDS, in a dose-dependent fashion. Given that (1) DRA has high similarity to other identified sulfate transporters and the proposed structure of DRA polypeptide is characteristic of those transporters, (2) DRA localization is limited to the cell membrane, and (3) DRA expression correlates with intestinal differentiation in mouse, we suggest that DRA represents a tissue-specific member of the sulfate transporter family.

Enantioselective deprotonation reactions using polymer-supported chiral magnesium amide bases

Novel and readily accessible polymer-supported chiral magnesium amide reagents have been prepared and shown to be effective in the asymmetric deprotonation of a series of prochiral cyclohexanones, affording good to excellent levels of both conversion and enantiomeric ratio (up to 93:7); the Merrifield-based chiral amine species has been shown to be readily recyclable.

Cloning and sequence analysis of Hsp89alpha DeltaN, a new member of theHsp90 gene family

We have identified a novel member of the Hsp90 gene family. This new gene, Hsp89alpha DeltaN, is remarkable in that it appears to represent a recent evolutionary event. Hsp89alpha DeltaN is identical in nucleotide sequence to Hsp89alpha for codons 224 to 732 (end). However, Hsp89alpha DeltaN cDNA lacks the ATP/geldanamycin binding domain (codons 1-220), instead containing 544 nucleotides of unique DNA at its 5' end including 30 novel codons.

Hindbrain and Spinal Cord Contributions to the Cutaneous Sensory Innervation of the Larval Zebrafish Pectoral Fin

Vertebrate forelimbs contain arrays of sensory neuron fibers that transmit signals from the skin to the nervous system. We used the genetic toolkit and optical clarity of the larval zebrafish to conduct a live imaging study of the sensory neurons innervating the pectoral fin skin. Sensory neurons in both the hindbrain and the spinal cord innervate the fin, with most cells located in the hindbrain. The hindbrain somas are located in rhombomere seven/eight, laterally and dorsally displaced from the pectoral fin motor pool. The spinal cord somas are located in the most anterior part of the cord, aligned with myomere four. Single cell reconstructions were used to map afferent processes and compare the distributions of processes to soma locations. Reconstructions indicate that this sensory system breaks from the canonical somatotopic organization of sensory systems by lacking a clear organization with reference to fin region. Arborizations from a single cell branch widely over the skin, innervating the axial skin, lateral fin surface, and medial fin surface. The extensive branching over the fin and the surrounding axial surface suggests that these fin sensory neurons report on general conditions of the fin area rather than providing fine location specificity, as has been demonstrated in other vertebrate limbs. With neuron reconstructions that span the full primary afferent arborization from the soma to the peripheral cutaneous innervation, this neuroanatomical study describes a system of primary sensory neurons and lays the groundwork for future functional studies.

Dichlorobis(dibenzylamino)bis(tetrahydrofuran)zirconium(IV) toluene hemisolvate

The title complex, [ZrCl2(C4H8O)2(C14H14N)2].0.5C7H8, was prepared in an unusual manner by utilizing [Mg[N(CH2Ph)2]2] as a ligand transfer reagent. The Zr atom lies in a distorted octahedral environment where steric repulsion from the large dibenzylamino ligands leads to a widening of the N-Zr-N angle [99.95 (9) degrees ] and corresponding compression of other angles [Cl-Zr-Cl 160.95 (3) degrees and O-Zr-O 78.22 (7) degrees ]. This distortion is compared with those found in the previously determined structures of the dimethylamino and diethylamino analogues.

Differential expression of S19 ribosomal protein, laminin-binding protein, and human lymphocyte antigen class I messenger RNAs associated with colon carcinoma progression and differentiation

Three complementary DNA encoding S19 ribosomal protein (S19), laminin-binding protein (LBP), and HLA class I (HLA-I) genes were isolated from a colon tumor-enriched subtraction library. To evaluate this mRNA expression, surgically removed colon tumors as well as matched normal tissue and human colon carcinoma cell lines showing various differentiation states, anchorage dependence, and proliferation states were examined by Northern blot analysis. The mRNA level of S19 mRNA (0.6 kilobase) was higher in primary colon carcinoma tissue than in matched normal colon tissue in 5 of 6 cases. In 2 of 4 cases, the expression of LBP mRNA (1.2 kilobases) was higher in carcinoma than in normal tissue. In 12 human colon cell lines, the level of LBP mRNA was higher in poorly differentiated cells. On the other hand, HLA-I mRNA (1.7 kilobases) was higher in well-differentiated cells. Although the S19 mRNA was expressed in both well- and poorly differentiated cells, a concomitant increase with tumor progression was observed in two pairs of cell lines derived from the same patients (SW480 and SW620; COLO201 and COLO205). Anchorage dependence of butyrate-treated HT29 colon carcinoma cells was correlated with lower levels of S19 and LBP mRNAs and higher levels of HLA-I mRNA expression compared with untreated cells. While the expression of S19 and LBP mRNAs was not changed due to cell growth states, HLA-I mRNA levels were found to be low in proliferating HT29 cells but highly induced in contact-inhibited cells. In summary, therefore, high expression of S19 and LBP combined with low expression of HLA-I were well correlated with colon carcinoma cells of higher malignant potential.

Down-regulation of the down-regulated in adenoma (DRA) gene correlates with colon tumor progression

The down-regulated in adenoma (DRA) gene was originally identified as a gene that was down-regulated in colon tumors. It encodes a protein with anion transporter function that is expressed predominantly in the mucosa of the lower gastrointestinal tract. In this study, expression of DRA and its cellular distribution have been investigated in a series of benign adenomatous polyps and malignant colorectal tumors and in corresponding normal colonic mucosa. We show that DRA mRNA and protein are expressed in all normal colonic tissue specimens with the protein restricted primarily to the terminally differentiated columnar epithelium and some goblet cells. Apical membrane localization was especially apparent in the columnar epithelium. The levels of DRA mRNA transcripts were down-regulated in all colon tumors examined relative to matched normal mucosa, with most specimens showing undetectable levels of DRA mRNA (77 of 104 tumors). DRA down-regulation was positively associated with colonic tumor progression according to Dukes' stage and was particularly significant in the early transition from normal mucosa to polyp to adenocarcinoma. DRA expression does not appear to be strictly associated with colonic cell differentiation; rather, its absence and down-regulation were associated with the proliferating component of the crypt epithelium and with neoplastic transformation, respectively.

The down-regulated in adenoma (DRA) gene encodes an intestine-specific membrane glycoprotein

The protein product of the DRA gene, a gene whose expression is down-regulated in colon adenomas and adenocarcinomas, is a membrane glycoprotein and a member of a family of sulfate transporters. It is expressed in the intestinal tract (duodenum, ileum, cecum, distal colon), but not in the esophagus or stomach. DRA mRNA expression is restricted to the mucosal epithelium, and DRA protein expression is further limited to the columnar epithelial cells, particularly to the brush border. Consistent with its expression in the differentiated columnar epithelium of the adult human colon, DRA is first expressed in the midgut of developing mouse embryos at day 16.5, corresponding with the time of differentiation of the epithelium of the small intestine. A model for the structure of the DRA protein is proposed and its possible role in colon tumorigenesis is discussed.

Oncogenes in hematopoietic and hepatic fish neoplasms

Neoplastic transformation of cells has often been associated with changes in cellular oncogenes. While much information has been collected in mammalian systems, relatively little is known about the molecular basis of tumor progression in lower vertebrates. For our studies, tumors were collected from feral northern pike (Esox lucius) from Ostego Lake, MI, where the local population exhibited a 15% incidence of large external lymphomas. In laboratory studies, tumors were induced under controlled conditions by known mammalian carcinogens in the Japanese medaka (Oryzias latipes), a small aquarium fish widely used in carcinogenicity studies. DNA isolated from these tumors was assayed for transforming sequences by transfection into NIH3T3 cells. DNAs from the northern pike lymphomas and the chemically induced tumors in the medaka were able to transform NIH3T3 cells and induce tumors in athymic mice. The results of our studies to date are summarized here, together with the current status of oncogene activation in other fish systems.