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PubMedDate not supplied

[Identification and characterization of differentially expressed ESTs of Gossypium barbadense infected by Verticillium dahliae with suppression subtractive hybridization].

Cotton wilt defense reaction is a complicated continuous process and involves a battery of genes. In this study, we adopted suppression subtractive hybridization (SSH) technique to isolate differentially expressed ESTs from Gossypium barbadense variety 7124 during Verticillium wilt defense process. An array of 1165 clones from the subtractive library has been screened with reverse northern blotting, of which 131 ESTs were considered as over-expressed and 16 ESTs were down-regulated. Sequence analysis and blast search showed that 83 ESTs were homologous to 45 unique sequences in the databases. Among all these differentially expressed ESTs, at least three kinds of genes were characterized. The majority of ESTs with deduced identity to aerobic metabolism enzymes strongly expressed in the infection process. Likewise, ESTs similar to those reported for pathogen-related protein genes were also picked out in this study. These ESTs in combination with other kinase-like genes and a defensin-like EST constituted an assembly of genes responded during pathogens' infection. These results imply that sea-island cotton undergoes strong oxidative stress and results in a series of defense responses when attacked by V. dahliae. To our knowledge, this is the first report on the isolation of global ESTs during sea-island cotton defense reaction.

Base Sequence↗
PubMed2002

Differential expression of a chloride intracellular channel gene, CLIC4, in transforming growth factor-beta1-mediated conversion of fibroblasts to myofibroblasts.

Conversion of fibroblasts into myofibroblasts as mediated by transforming growth factor-beta1 (TGF-beta1) is the most prominent stromal reaction to a number of epithelial lesions including breast cancer. To identify genes which are regulated during this process, the mRNA profiles from primary breast fibroblasts treated with or without TGF-beta1 were analyzed by differential display. Ninety-five differentially expressed transcripts were PCR-cloned and sequenced, and 28 clones were selected for verification in a hybridization array. By use of gene-specific sequence tags, nine differentially expressed genes were identified. One of the clones, identified as CLIC4, a member of the CLIC family of chloride channels, was up-regulated more than 16 times in myofibroblasts and was therefore chosen for further analysis. Using RT-PCR, comparison with CLIC1, CLIC2, CLIC3, and CLIC5 demonstrated that CLIC4 was unique by being up-regulated by TGF-beta1 in myofibroblasts. Immunohistochemistry showed a hitherto unknown, distinctive pattern of CLIC4 expression in breast stroma. Whereas normal breast fibroblasts were devoid of CLIC4 protein expression, myofibroblasts of breast carcinomas were strongly CLIC4-positive. The functional significance of CLIC4 was analyzed in MEF/3T3 fibroblasts by conditional expression using the tetracycline-repressive gene regulation system. In a migration assay, we found that CLIC4 inhibited cell motility by 27%. These results suggest that CLIC4 is differentially regulated in fibroblasts and that its expression contributes to a collective stationary myofibroblast phenotype.

Breast↗
PubMed2002

Differential expression profiling of head and neck squamous carcinoma: significance in their phenotypic and biological classification.

The genetic events associated with the development and progression of head and neck squamous carcinoma (HNSC) are largely unknown. We analysed 12 matched pairs of histologically normal squamous mucosa and tumor specimens from six conventional and six phenotypic variants HNSC to define the differentially expressed genes in these tumors. Parallel expression analysis of 8055 unique genes was performed, and the level of the hybridization signal for each gene was measured after normalization. Hierarchical cluster analysis of the expressed genes showed distinct inter- and intra-tumoral patterns in and between conventional squamous carcinoma and squamous carcinoma variants. We also identified 26 (0.32%) differentially expressed genes that were consistently different between matched pairs of normal and tumor specimens; a selected set of the overexpressed genes was validated using real-time quantitative RT-PCR. The majority of the genes were associated with differentiation and proliferation. Our study defines a set of genes that could form the basis for the construction of limited HNSC targeted expression array and in-depth studies and further highlights gene profile differences that may be useful in pathobiologic classification of HNSC.

Adult↗
PubMed2000

Differential expression of Bcl-2-related proteins in differentiating NT2 cells.

Although the role of Bcl-2-related proteins as regulators of the apoptotic process has been well documented, recent studies suggest that they might also be implicated in neuronal differentiation. We have studied by immunocytochemistry, Western blotting and RT-PCR the expression pattern of Bcl-xL, Bcl-2 and BAX in the in vitro model of neuronal differentiation constituted by retinoic acid (RA)-treated NTera-2/D1 (NT2/D1) cells. Whereas BAX level did not change significantly during the RA treatment, Bcl-xL level increased markedly during the first week, before returning to basal level during the second week. Bcl-2 expression, undetectable in undifferentiated cells, increased progressively from the first week. From our results, we suggest that, at least in our model, Bcl-2-related proteins might be involved in neuronal differentiation.

Apoptosis↗
PubMed2000

Differentially expressed genes in two LNCaP prostate cancer cell lines reflecting changes during prostate cancer progression.

Prostate cancer tends to become transformed to androgen-independent disease over time when treated by androgen-deprivation therapy. We used two variants of the human prostate cancer cell line LNCaP to study gene expression differences during prostate cancer progression to androgen-independent disease. Production of prostate-specific antigen was regarded as a marker of androgen-dependence and loss of prostate-specific antigen was regarded as a marker of androgen-independence. mRNA from both cell lines was used for cDNA microarray screening. Differential expression of several genes was confirmed by Northern blotting. Monoamine oxidase A, an Expressed Sequence Tag (EST) similar to rat P044, and EST AA412049 were highly overexpressed in androgen-dependent LNCaP cells. Tissue-type plasminogen activator, interferon-inducible protein p78 (MxB), an EST similar to galectin-1, follistatin, fatty acid-binding protein 5, EST AA609749, annexin I, the interferon-inducible gene 1-8U, and phospholipase D1 were highly overexpressed in androgen-independent LNCaP cells. All studied genes had low or no expression in PC-3 cells. The EST similar to rat P044, the EST similar to galectin-1, follistatin, annexin I, and the interferon-inducible gene 1-8U were also expressed in benign prostatic hyperplasia tissue. The Y-linked ribosomal protein S4, Mat-8, and EST AA307912 were highly expressed in benign prostatic hyperplasia tissue. Additionally, both confirmation of differential expression in Northern blots and in situ hybridization were carried out for monoamine oxidase A, the EST similar to rat P044, the EST similar to galectin-1, fatty acid-binding protein 5, and the interferon-inducible gene 1-8U. We identified several potential prostate cancer markers, indicating that the method used is a useful tool for the screening of cancer markers, but other methods, such as in situ hybridization, are needed to further investigate the observations.

Animals↗
PubMed2005

Identification of novel differentially expressed genes in human astrocytomas by cDNA representational difference analysis.

Diffuse infiltrating gliomas are the most common tumors of the central nervous system (CNS), naturally progressing from a lower-grade to a higher-grade malignancy. Several genetic alterations have been correlated with astrocytic tumors; however, a number of as yet unknown genes may also be involved. Therefore, we set out to search for genes that are differentially expressed in anaplastic astrocytoma and normal CNS tissue by applying a PCR-based subtractive hybridization approach, namely, representational difference analysis (RDA). The results of DNA sequencing of a sample (96 cDNA clones) from the subtracted library allowed the identification of 18 different genes, some of which were represented by several cDNA clones, coding for the Np95, LMO1, FCGBP, DSCAM, and taxilin proteins. Quantitative real-time PCR analysis for five of these genes was performed using samples of astrocytic tumors of different grades, confirming their higher expression when compared to non-tumoral CNS tissue. Identification of differentially expressed genes present in gliomas but not in normal CNS tissue is important not only to better understand the molecular basis of these cancers, but also to generate diagnostic DNA chips, which may be useful in future therapeutic intervention.

Base Sequence↗
PubMed2006

Hepatocyte growth factor-regulated tyrosine kinase substrate (HGS) and guanylate kinase 1 (GUK1) are differentially expressed in GH-secreting adenomas.

Pituitary tumors, adenomas in their vast majority, represent around 10-15% of the intracranial neoplasms. Pituitary carcinomas are exceedingly rare. Clinically, these neoplasms cause hormonal dysfunctions, and mass effect symptoms as headache and visual disorders in the case of macroadenomas. Pituitary tumorigenesis is still poorly understood. In order to investigate the expression of cancer-related genes in pituitary tumors, we employed a human cancer cDNA macroarray membrane with 1176 well-characterized human genes related to cancer and tumor biology. We were able to identify several differentially expressed genes, among them hepatocyte growth factor-regulated tyrosine kinase substrate (HGS) and guanylate kinase 1 (GUK1) which were over expressed in a pool of clinically nonfunctioning pituitary adenomas, compared with a spinal cord metastasis of a nonfunctioning pituitary carcinoma. HGS and GUK1 mRNA expression were chosen to be validated by quantitative RT-qPCR, however, only GUK1 had the differential expression confirmed between the adenomas and the metastasis of a pituitary carcinoma. We have also investigated HGS and GUK1 mRNA expressions in a series of 46 pituitary adenomas (18 nonfunctioning, 12 GH-secreting, nine PRL-secreting, and seven ACTH-secreting adenomas). HGS and GUK1 were significantly over expressed in GH-secreting adenomas, compared with ACTH-secreting adenomas and nonfunctioning tumors, and with PRL-secreting adenomas, respectively. We have shown that these genes, involved in tumorigenesis in other tissues, are as well over expressed in the pituitary tumors, however, their role in the oncogenesis of these tumors need to be further investigated.

ACTH-Secreting Pituitary Adenoma↗
PubMed2004

Differential expression of mast cell characteristics in human myeloid cell lines.

In order to better understand the mechanisms governing display of mast cell characteristics in human myeloid cells, we have studied the mast cell phenotype in human promyelocytic (HL-60) and myelocytic (U-937, TPH-1) vs. basophilic (KU-812) and mast cell (HMC-1) lines, in part also in skin mast cells and blood monocytes, at mRNA and protein level before and after stimulation with mast cell growth factors. In unstimulated cells, mRNA for the stem cell factor (SCF) receptor c-kit and the gamma chain of the high-affinity IgE receptor (FcepsilonRI) was noted in all cells studied. Like mast and basophilic cells, THP-1 cells expressed the FcepsilonRIalpha and beta chains and weakly histidine decarboxylase (HDC), but they lacked mRNA for mast cell-specific proteases [tryptase, chymase, carboxypeptidase A (CPA)]. In contrast, HL-60 and U-937 cells lacked FcepsilonRIalpha, but expressed tryptase and chymase, HL-60 cells also CPA. KU-812 cells failed to express the basophil-specific marker 2D7. After a 10-day culture with SCF or fibroblast supernatants, baseline mRNA expression of most mast cell characteristics was upregulated, whereas c-kit mRNA expression decreased in all but THP-1 cells. Differential mRNA expression of FcepsilonRI vs. protease (tryptase) was confirmed at protein level by immunocytochemistry and enzymatic activity. KU-812 cells are thus closest to skin mast cells in that they express all molecules studied, except for chymase, followed by THP-1 cells that lack all mast cell proteases. In contrast, HL-60 and U-937 cells fail to express the FcepsilonRIalpha and beta chains but express most mast cell proteases. The selective and differential expression of mast cell characteristics in human myeloid cell lines suggests that induction of the mast cell phenotype is regulated by several independent genes and that mast cells and basophils branch off at early and distinct points of myeloid development.

Cell Differentiation↗
PubMed2007

Genetic network and pathway analysis of differentially expressed proteins during critical cellular events in fracture repair.

Bone repair consists of inflammation, intramembranous ossification, chondrogenesis, endochondral ossification, and remodeling. To better understand the translational regulation of these distinct but interrelated cellular events, we used the second generation of BD Clontechtrade mark Antibody Microarray to dissect and functionally characterize proteins differentially expressed between intact and fractured rat femur at each of these cellular events. Genetic network analysis showed that proteins differentially expressed within a given cellular event tend to be physically or functionally correlated. Seventeen such interacting networks were established over five cellular events that were most frequently associated with cell cycle, cell death, cell-to-cell signaling and interaction, and cell growth and proliferation. Eighteen molecular pathways were significantly enriched during the bone repair process, of which ERK/MAPK, NF-kB, PDGF, and T-cell receptor signaling pathways were significant during three or more cellular events. The analyses revealed dynamic temporal expression patterns and cellular-event-specific functions. The inflammation event on Day 1 was characteristic of the cell cycle-related molecular changes. The relative quiet stage of intramembranous ossification on Day 4 and the molecularly most active stage of chondrogenesis on Day 7 were featured by coordinated cell death and cell-proliferation signals. Endochondral ossification on Day 14 experienced a clear transition from the molecular/cellular function to the physiological system development/function. The osteoclast-mediated remodeling on Day 28 was highlighted by the integrin signaling pathway. The distinct changes in protein expression during these cellular events provide a molecular basis for developing cellular event-targeted therapeutic strategy to accelerate bone healing.

Animals↗
PubMedDate not supplied

Identification and molecular characterization of five novel kallikrein gene 13 (KLK13; KLK-L4) splice variants: differential expression in the human testis and testicular cancer.

The kallikrein gene family is comprised of genes that have either established or potential applications in prostate and breast cancer diagnostics. New members of the human kallikrein gene family have been recently identified. By using the positional candidate gene approach, we were able to clone a novel human serine protease gene that maps to chromosome 19q13.3-q13.4, the location of the kallikrein gene family. We named this gene KLK-L4 (now also known as KLK13). Here, we describe the identification of five new KLK-L4 splice variants which are not expressed in any other tissue except the human testis. We have further established that these splice variants can be detected in normal testis but not in the adjacent matched testicular tumors. In addition, differential expression of the KLK-L4 gene was found in various histological types of testicular cancer. Our results suggest that the KLK-L4 gene is expressed in normal and cancerous testicular tissue; however, its five variants are all expressed in normal tissue but not in testicular tumors. The physiological relevance of these variants and the implications of their differential expression between cancerous and normal tissues are currently unknown.

Alternative Splicing↗
PubMed2000

In vitro cloning of complex mixtures of DNA on microbeads: physical separation of differentially expressed cDNAs.

We describe a method for cloning nucleic acid molecules onto the surfaces of 5-micrometer microbeads rather than in biological hosts. A unique tag sequence is attached to each molecule, and the tagged library is amplified. Unique tagging of the molecules is achieved by sampling a small fraction (1%) of a very large repertoire of tag sequences. The resulting library is hybridized to microbeads that each carry approximately 10(6) strands complementary to one of the tags. About 10(5) copies of each molecule are collected on each microbead. Because such clones are segregated on microbeads, they can be operated on simultaneously and then assayed separately. To demonstrate the utility of this approach, we show how to label and extract microbeads bearing clones differentially expressed between two libraries by using a fluorescence-activated cell sorter (FACS). Because no prior information about the cloned molecules is required, this process is obviously useful where sequence databases are incomplete or nonexistent. More importantly, the process also permits the isolation of clones that are expressed only in given tissues or that are differentially expressed between normal and diseased states. Such clones then may be spotted on much more cost-effective, tissue- or disease-directed, low-density planar microarrays.

Cloning, Molecular↗
PubMed2005

Differential expression of IGF system components in proliferating vs. differentiating growth plate chondrocytes: the functional role of IGFBP-5.

The growth plate is an important target tissue for insulin-like growth factors (IGFs), but little is known about the regulation of the IGF system during the developmental sequence of chondrocytes. We therefore examined the expression profile of IGF system components in proliferating vs. differentiating growth plate chondrocytes by use of two cell culture models of the growth cartilage. In rat growth plate chondrocytes in primary culture, IGF-I expression increased twofold during the process of differentiation. IGF-binding protein-3 (IGFBP-3) expression showed a biphasic pattern of with a twofold increase at the onset of differentiation and a downregulation in late differentiating chondrocytes to 25% of baseline levels; the expression patterns of IGFBP-2, -4 and -6 were not dependent on the developmental stage. In IGF- and IGFBP-3-deficient RCJ3.1C5.18 (RCJ) mesenchymal chondrogenic cells, IGFBP-2 and -6 synthesis declined by 50% during differentiation. IGFBP-5 expression was markedly upregulated during the process of differentiation in both cell culture models. Although IGFBP-5 overexpression did not have an IGF-independent effect on RCJ cell differentiation, it promoted IGF-I-enhanced differentiation of these cells. A potential mechanism for this effect is the specific increase of Akt phosphorylation in IGFBP-5-overexpressing cells in the presence of IGF-I, indicating an increased activity of the phosphatidylinositol (PI) 3-kinase pathway. These data suggest that the developmental stage of the chondrocyte is an important determinant of IGF and IGFBP expression and imply a functional role for IGFBP-5 for upregulating IGF action during chondrocyte differentiation in vivo.

Animals↗
PubMed1997

Differential expression of integrins and laminin-5 in normal oral epithelia.

beta 1 and beta 4 integrins are receptors on epithelial cells mediating cell-extracellular matrix adhesion. Furthermore, alpha 2 beta 1 and alpha 3 beta 1 contribute to cell-cell adhesion. Laminin-5 in epithelial basement membranes (BMs) is a ligand for alpha 6 beta 4 and alpha 3 beta 1. Expression of different integrins and laminin-5 was studied in oral epithelium to characterize regional variations in these adhesion molecules. Monoclonal antibodies directed against alpha 2-alpha 6 beta 1/alpha 6 beta 4 and laminin-5 were examined in cryopreserved biopsies of normal mucosa by immunohistochemistry. Laminin-5 was expressed as a line along the BMs. The junctional epithelium showed a unique phenotype: Laminin-5 was detected in the internal BM at the tooth surface and in the external BM, where excessive laminin-5 was seen in the stroma. alpha 6 beta 4 was expressed in all cells of the junctional epithelium. Integrins alpha 4 beta 1 and alpha 5 beta 1 were not detected in the epithelia, whereas alpha 2 beta 1 and alpha 3 beta 1 showed differential expression. Epithelia with well-developed rete pegs and connective tissue papillae showed polarized alpha 3 beta 1 expression along the BM in the rete pegs, in contrast to negative expression at the tips of the connective tissue papillae. A variation in the suprabasal distribution of alpha 2 beta 1 and alpha 3 beta 1 was observed between epithelia from different regions. alpha 2 beta 1 and alpha 3 beta 1 were detected in basal/parabasal cells in keratinized epithelia, whereas there was increased suprabasal expression in nonkeratinized mucosa. These results indicate inhomogeneity in the basal cell population of oral squamous epithelia and differential expression of integrins, which may reflect differences in the underlying stroma. Laminin-5 deposits in the stroma underneath the junctional epithelium may indicate subclinical gingival inflammation.

Adult↗
PubMed1999

Encoding of Ca2+ signals by differential expression of IP3 receptor subtypes.

Inositol 1,4,5-trisphosphate (IP3) plays a key role in Ca2+ signalling, which exhibits a variety of spatio-temporal patterns that control important cell functions. Multiple subtypes of IP3 receptors (IP3R-1, -2 and -3) are expressed in a tissue- and development-specific manner and form heterotetrameric channels through which stored Ca2+ is released, but the physiological significance of the differential expression of IP3R subtypes is not known. We have studied the Ca2+-signalling mechanism in genetically engineered B cells that express either a single or a combination of IP3R subtypes, and show that Ca2+-signalling patterns depend on the IP3R subtypes, which differ significantly in their response to agonists, i.e. IP3, Ca2+ and ATP. IP3R-2 is the most sensitive to IP3 and is required for the long lasting, regular Ca2+ oscillations that occur upon activation of B-cell receptors. IP3R-1 is highly sensitive to ATP and mediates less regular Ca2+ oscillations. IP3R-3 is the least sensitive to IP3 and Ca2+, and tends to generate monophasic Ca2+ transients. Furthermore, we show for the first time functional interactions between coexpressed subtypes. Our results demonstrate that differential expression of IP3R subtypes helps to encode IP3-mediated Ca2+ signalling.

Adenosine Triphosphate↗
PubMed2002

Use of cDNA arrays to generate differential expression profiles for inflammatory genes in human gestational membranes delivered at term and preterm.

Inflammatory processes are implicated in preterm labour (PTL). To identify potential novel markers for PTL, we have used commercial cDNA arrays to generate profiles of differential expression of inflammation-associated genes in gestational membranes with term and PTL. RNA for cDNA probe synthesis was isolated from reflected human amnion and choriodecidua membranes delivered following Caesarean section at term before the onset of labour (TNL, n = 4), spontaneous labour at term (TSL, n = 4), and PTL with and without chorioamnionitis (PTL(+INF) and PTL(-INF) respectively, n = 4 each). Profiles were displayed relative to TNL and statistical comparisons of TSL versus TNL and PTL(+INF) versus PTL(-INF) were performed. Elevated expression of chemokines macrophage inflammatory protein 1beta(MIP-1beta) and pulmonary and activation-regulated chemokine (PARC) was observed in PTL(+INF) compared to PTL(-INF) amnion and choriodecidua respectively (P = 0.03). Likewise, the cytokines oncostatin-M and pre-B cell enhancing factor (PBEF) were more highly expressed in PTL(+INF) compared with PTL(-INF) and in TSL compared with TNL respectively (P = 0.03). Conversely, inhibin A, tissue inhibitors of matrix metalloproteinase (TIMP)-3 and TIMP-4 were all significantly elevated in PTL(-INF) compared with PTL(+INF) (P = 0.03). Furthermore, differential expression patterns of classes of genes, grouped according to function (e.g. chemokines), were noted. The cDNA array approach holds promise for identification of new candidate markers or combinations thereof for prediction or diagnosis of PTL, as well as for increasing our understanding of the particular aetiologies involved.

Cytokines↗
PubMed2026

The prognostic value and molecular mechanisms of Porphyromonas gingivalis infection-associated differentially expressed genes in oral squamous cell carcinoma.

BACKGROUND: Increasing evidence suggests that Porphyromonas gingivalis (Pg) is associated with oral squamous cell carcinoma (OSCC) development and progression. This study aimed to identify Pg-associated genes with prognostic relevance in OSCC through integrated bioinformatics analysis. METHODS: OSCC-related differentially expressed genes (DEGs) were identified from the The Cancer Genome Atlas (TCGA)-OSCC cohort and intersected with Pg supernatant-associated DEGs from GSE192887. Raw count data were analyzed with DESeq2, whereas transcripts per million (TPM)-transformed expression values were used for downstream visualization and model construction. Weighted gene co-expression network analysis (WGCNA), univariate Cox regression, least absolute shrinkage and selection operator (LASSO) regression, and multivariable Cox modeling were used to develop a seven-gene prognostic signature, which was externally evaluated in GSE41613. Additional analyses examined treatment-associated expression changes in the seven model genes, pairwise correlations among the model genes, and correlations between Pg supernatant-associated differentially expressed gene (PgSDEG)-derived module eigengenes and immune-cell fractions. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was performed in eight paired OSCC and adjacent non-tumor tissues and in supplemented-brain heart infusion (BHI) vehicle-control and Pg culture-supernatant-treated HOK, HSC-3, and CAL-27 cells. RESULTS: A prognostic signature comprising CXCL8, GAST, HBQ1, PADI3, STC1, TEX19, and TMEM92 was established. The signature showed limited-to-moderate discrimination in the TCGA training cohort, with 1-, 3-, and 5-year areas under the curve (AUCs) of 0.68, 0.69, and 0.69, respectively, and limited discrimination in the GSE41613 external cohort (AUCs: 0.66, 0.67, and 0.61). Kaplan-Meier analysis showed poorer survival in the high-risk group in both cohorts. The GSE192887 analysis showed significant treatment-associated expression changes in all seven genes after Pg culture-supernatant exposure. In paired tissues, CXCL8 and TMEM92 were significantly higher in OSCC tissues, whereas STC1 was not significant after Holm correction. In CAL-27 cells, CXCL8, STC1, and TMEM92 increased significantly after culture-supernatant treatment, whereas the corresponding comparisons were not significant in HOK or HSC-3 cells after adjustment. CONCLUSIONS: This study developed a seven-gene Pg-associated prognostic signature for OSCC and provided complementary transcriptomic, immune-correlation, tissue, and cell-based evidence that placed the signature in biological context. The model showed limited-to-moderate discrimination and is not ready for clinical use. The enrichment, gene-correlation, and immune-correlation findings are hypothesis-generating rather than mechanistic evidence. Further independent validation and dedicated functional studies are required.

Oral squamous cell carcinoma (OSCC)↗
PubMed2003

Reversed-phase high-performance liquid chromatography prefractionation prior to two-dimensional difference gel electrophoresis and mass spectrometry identifies new differentially expressed proteins between striate cortex of kitten and adult cat.

Two-dimensional difference gel electrophoresis (2-D DIGE), in combination with mass spectrometry, is a highly effective method for the rapid and reproducible detection of differentially expressed proteins. This approach, however, has the unfortunate drawback that it preferentially displays rather abundantly expressed proteins. Nevertheless, comparison of the protein expression levels of the striate cortex of adult cats and 30-day-old kittens, resulted in the identification of several proteins related to postnatal brain development and possibly age-dependent plasticity as well (Van den Bergh et al., J. Neurochem. 2003, in press). The goal of the present study was the selective enrichment and identification of less abundant proteins within the same paradigm. Hereto, we performed a reversed-phase chromatography prefractionation of our tissue lysate to separate the proteins in four fractions based on their hydrophobicity prior to 2-D DIGE analysis. This approach not only confirmed the differential expression levels of a number of proteins from the previous study, but also identified three additional proteins preferentially expressed in kitten visual cortex and five additional proteins with higher expression levels in adult cat visual cortex. These spots were not visible on the total tissue lysate protein maps, indicating that the high-performance liquid chromatography (HPLC) prefractionation enabled us to visualize additional, less abundant proteins.

Age Factors↗
PubMed1999

Differential expressions of CD44 variants in tumors affecting the central nervous system.

BACKGROUND: The polymorphic cell adhesion molecule CD44 exists as a family of proteins generated by extensive alternative splicing of the CD44 pre-messenger RNA and marked posttranslational modification. The differential expression of CD44 isoforms in a variety of human cancers has been proposed to influence tumorigenesis and metastasis. In this study, CD44 gene expression was analyzed in primary and metastatic tumors and in cell lines derived from tumors that affect the central nervous system (CNS), including tumors metastatic to the spine. MATERIALS AND METHODS: Fifty-four samples were subjected to semiquantitative reverse-transcriptase polymerase chain reaction with CD44-specific primers and hybridized individually with probes specific for the CD44 variant (CD44v) exons v3 to v10. RESULTS: Compared with CD44v-positive breast cancer cell lines and CD44v-negative normal brain tissue, CD44v expression was weak in primary brain tumors and cell lines derived from normal brain and tumor tissue. However, high levels of isoforms encoding multiple-variant exons were shown in all metastatic brain tumors. In contrast, tumors metastatic to the spine were virtually negative for CD44v expression. Several rare CD44 isoforms composed of single-variant exons v3, v4, v6, or v9 were identified in primary brain tumors and may reflect their invasive potential or culturability in vitro. CONCLUSION: These data suggest differential expression of CD44v may substantially influence the end-organ site of metastasis for tumor cells destined for the CNS.

Antigens, Neoplasm↗