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Microarray Screening (microarray + screening)

Distribution by Scientific Domains

Medical Sciences	57%
Life Sciences	42%

Selected Abstracts

Calcium/calcineurin signaling in primary cortical astrocyte cultures: Rcan1-4 and cyclooxygenase-2 as NFAT target genes

GLIA, Issue 7 2008
Andrea Canellada
Abstract The calcineurin/nuclear factor of activated T cells (NFAT) signaling pathway mediates important cell responses to calcium, but its activity and function in astrocytes have remained unclear. We show that primary cortical astrocyte cultures express the regulatory and catalytic subunits of the phosphatase calcineurin as well as the calcium-regulated NFAT family members (NFATc1, c2, c3, and c4). NFATs are activated by calcium-mobilizing agents in astrocytes, and this activation is blocked by the calcineurin inhibitor cyclosporine A. Microarray screening identified cyclooxygenase-2 (Cox-2), which is implicated in brain injury, and Rcan 1-4, an endogenous calcineurin inhibitor, as genes up-regulated by calcineurin-dependent calcium signals in astrocytes. Mobilization of intracellular calcium with ionophore potently augments the promoter activity and mRNA and protein expression of Rcan 1-4 and Cox-2 induced by combined treatment with phorbol esters. Moreover, Rcan 1-4 expression is efficiently induced by calcium mobilization alone. For both the genes, the calcium signal component is dependent on calcineurin and is replicated by exogenous expression of a constitutively active NFAT, strongly suggesting that the calcium-induced gene activation is mediated by NFATs. Finally, we report that calcineurin-dependent expression of Cox-2 and Rcan 1-4 is induced by physiological calcium mobilizing agents, such as thrombin, agonists of purinergic and glutamate receptors, and L-type voltage-gated calcium channels. These findings provide insights into calcium-initiated gene transcription in astrocytes, and have implications for the regulation of calcium responses in astrocytes. © 2008 Wiley-Liss, Inc. [source]

Identification of novel markers expressed during fin regeneration by microarray analysis in medaka fish

DEVELOPMENTAL DYNAMICS, Issue 9 2007
Masanobu Nishidate
Abstract Urodeles and fish have a remarkable ability to regenerate lost body parts, whereas many higher vertebrates, including mammals, retain only a limited capacity. It is known that the formation of specialized cell populations such as the wound epidermis or blastema is crucial for regeneration; however, the molecular basis for their formation has not been elucidated. Recently, approaches using differential display and microarray have been done in zebrafish for searching molecules involved in regeneration. Here, we used the medaka fish, a distantly diverged fish species, for microarray screening of transcripts up-regulated during regeneration. By setting criteria for selecting transcripts that are reliably and reproducibly up-regulated during regeneration, we identified 140 transcripts. Of them, localized in situ expression of 12 transcripts of 22 tested was detected either in differentiating cartilage, basal wound epidermis, or blastema. Our results provide useful molecular markers for dissecting the regeneration process at a fine cellular resolution. Developmental Dynamics 236:2685,2693, 2007. © 2007 Wiley-Liss, Inc. [source]

Upregulation of the tumor suppressor gene menin in hepatocellular carcinomas and its significance in fibrogenesis,

HEPATOLOGY, Issue 5 2006
Pierre J. Zindy
The molecular mechanisms underlying the progression of cirrhosis toward hepatocellular carcinoma were investigated by a combination of DNA microarray analysis and literature data mining. By using a microarray screening of suppression subtractive hybridization cDNA libraries, we first analyzed genes differentially expressed in tumor and nontumor livers with cirrhosis from 15 patients with hepatocellular carcinomas. Seventy-four genes were similarly recovered in tumor (57.8% of differentially expressed genes) and adjacent nontumor tissues (64% of differentially expressed genes) compared with histologically normal livers. Gene ontology analyses revealed that downregulated genes (n = 35) were mostly associated with hepatic functions. Upregulated genes (n = 39) included both known genes associated with extracellular matrix remodeling, cell communication, metabolism, and post-transcriptional regulation gene (e.g., ZFP36L1), as well as the tumor suppressor gene menin (multiple endocrine neoplasia type 1; MEN1). MEN1 was further identified as an important node of a regulatory network graph that integrated array data with array-independent literature mining. Upregulation of MEN1 in tumor was confirmed in an independent set of samples and associated with tumor size (P = .016). In the underlying liver with cirrhosis, increased steady-state MEN1 mRNA levels were correlated with those of collagen ,2(I) mRNA (P < .01). In addition, MEN1 expression was associated with hepatic stellate cell activation during fibrogenesis and involved in transforming growth factor beta (TGF-,),dependent collagen ,2(I) regulation. In conclusion, menin is a key regulator of gene networks that are activated in fibrogenesis associated with hepatocellular carcinoma through the modulation of TGF-, response. (HEPATOLOGY 2006;44:1296,1307.) [source]

Detection of elafin as a candidate biomarker for ulcerative colitis by whole-genome microarray screening

INFLAMMATORY BOWEL DISEASES, Issue 9 2006
Carl-Fredrik Flach PhD
Abstract The cause of ulcerative colitis (UC) is largely unknown. Microarray studies are an efficient way of investigating the various genes involved. Here, we have used whole-genome microarrays to clarify the clinical picture and to identify new biomarkers for improved diagnosis. Rectal biopsies were taken from five UC patients and five matched controls, and RNA transcripts were prepared. After labeling, each sample was individually applied to the microarray chips. All transcripts that were more than 10-fold up-regulated in all five patients were analyzed further in seven additional patients and seven controls using quantitative polymerase chain reaction. Of 47,000 transcripts examined, 4 were highly up-regulated in all patients: those encoding elafin, a secreted protease inhibitor, the ion and amino acid transporter B0,+ (SLC6A14), and the metabolic enzyme aldolase B, as well as a recently identified transcript named similar to numb-interacting homolog. The up-regulation of these transcripts appears to follow the progression of the disease because elevated expression was detected in the proximal part of the colon in patients with total colitis but not in patients with left-sided colitis. Immunohistologic examination showed very distinct differences in the expression of elafin. Extensive expression was detected in enterocytes and goblet cells of the affected mucosa, whereas there was no detectable expression in unaffected mucosa and in healthy controls. The results implicate four transcripts and proteins of special interest as possible targets for pharmacologic interference and as biomarkers in UC. Of these, elafin may be of special interest because it is a secreted protein that may be measured in body fluids. [source]

Upregulation of miR-23a,27a,24 decreases transforming growth factor-beta-induced tumor-suppressive activities in human hepatocellular carcinoma cells

INTERNATIONAL JOURNAL OF CANCER, Issue 4 2008
Shenglin Huang
Abstract Transforming growth factor-beta (TGF-beta) plays a dual and complex role in human cancer. In this report, we observe a specific set of MicroRNAs (miRNAs) changed in response to TGF-beta in human hepatocellular carcinoma (HCC) cells by miRNA microarray screening. A cluster of miRNA, miR-23a,27a,24, is induced in an early stage by TGF-beta in Huh-7 cells. Knockdown of Smad4, Smad2 or Smad3 expression by RNA interference can attenuate the response of miR-23a,27a,24 to TGF-beta addition, indicating that this induction is dependent on Smad pathway. We also explore that miR-23a,27a,24 can function as an antiapoptotic and proliferation-promoting factor in liver cancer cells. In addition, expression of this miRNA cluster is found to be remarkably upregulated in HCC tissues versus normal liver tissues. These findings suggest a novel, alternative mechanism through which TGF-beta could induce specific miRNA expression to escape from tumor-suppressive response in HCC cells. © 2008 Wiley-Liss, Inc. [source]

MicroRNA regulation in Ames dwarf mouse liver may contribute to delayed aging

AGING CELL, Issue 1 2010
David J. Bates
Summary The Ames dwarf mouse is well known for its remarkable propensity to delay the onset of aging. Although significant advances have been made demonstrating that this aging phenotype results primarily from an endocrine imbalance, the post-transcriptional regulation of gene expression and its impact on longevity remains to be explored. Towards this end, we present the first comprehensive study by microRNA (miRNA) microarray screening to identify dwarf-specific lead miRNAs, and investigate their roles as pivotal molecular regulators directing the long-lived phenotype. Mapping the signature miRNAs to the inversely expressed putative target genes, followed by in situ immunohistochemical staining and in vitro correlation assays, reveals that dwarf mice post-transcriptionally regulate key proteins of intermediate metabolism, most importantly the biosynthetic pathway involving ornithine decarboxylase and spermidine synthase. Functional assays using 3,-untranslated region reporter constructs in co-transfection experiments confirm that miRNA-27a indeed suppresses the expression of both of these proteins, marking them as probable targets of this miRNA in vivo. Moreover, the putative repressed action of this miRNA on ornithine decarboxylase is identified in dwarf mouse liver as early as 2 months of age. Taken together, our results show that among the altered aspects of intermediate metabolism detected in the dwarf mouse liver , glutathione metabolism, the urea cycle and polyamine biosynthesis , miRNA-27a is a key post-transcriptional control. Furthermore, compared to its normal siblings, the dwarf mouse exhibits a head start in regulating these pathways to control their normality, which may ultimately contribute to its extended healthspan and longevity. [source]

Distinct Mechanism of Small-for-Size Fatty Liver Graft Injury,Wnt4 Signaling Activates Hepatic Stellate Cells

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 5 2010
Q. Cheng
In this study, we aimed to investigate the significance of hepatic stellate cells (HSCs) activation in small-for-size fatty liver graft injury and to explore the underlying molecular mechanism in a rat liver transplantation model. A rat orthotopic liver transplantation model using fatty grafts (40% of fatty changes) and cirrhotic recipients was applied. Intragraft gene expression profiles, ultrastructure features and HSCs activation were compared among the rats received different types of grafts (whole vs. small-for-size, normal vs. fatty). The distinct molecular signature of small-for-size fatty graft injury was identified by cDNA microarray screening and confirmed by RT-PCR detection. In vitro functional studies were further conducted to investigate the direct effect of specific molecular signature on HSCs activation. HSCs activation was predominantly present in small-for-size fatty grafts during the first 2 weeks after transplantation, and was strongly correlated with progressive hepatic sinusoidal damage and significant upregulation of intragraft Wnt4 signaling pathway. In vitro suppression of Wnt4 expression could inhibit HSC activation directly. In conclusion, upregulation of Wnt4 signaling led to direct HSC activation and subsequently induced small-for-size fatty liver grafts injury. Discovery of this distinct mechanism may lay the foundation for prophylactic treatment for marginal graft injury in living donor liver transplantation. [source]