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Samir Mehanović

Društvene mreže:

Debarpan Dhar, S. Mehanovic, Walter N. Moss, C. Miller

Mammalian orthoreovirus (MRV) is a prototypic member of the Spinareoviridae family and has ten double-stranded RNA segments. One copy of each segment must be faithfully packaged into the mature virion, and prior literature suggests that nucleotides (nts) at the terminal ends of each gene likely facilitate their packaging. However, little is known about the precise packaging sequences required or how the packaging process is coordinated. Using a novel approach, we have determined that 200 nts at each terminus, inclusive of untranslated regions (UTR) and parts of the open reading frame (ORF), are sufficient for packaging each S gene segment (S1-S4) individually and together into replicating virus. Further, we mapped the minimal sequences required for packaging the S1 gene segment to 25 5′ nts and 50 3′ nts. The S1 UTRs alone are not sufficient, but are necessary for packaging, as mutations of the 5′ or 3′ UTRs led to a complete loss of virus recovery. Using a second novel assay, we determined that 50 5′nts and 50 3′ nts of S1 are sufficient to package a non-viral gene segment into MRV. The 5′ and 3′ termini of the S1 gene are predicted to form a panhandle structure and specific mutations within the predicted stem of the panhandle region led to a significant decrease in viral recovery. Additionally, mutation of six nts that are conserved in the three major serotypes of MRV and are predicted to form an unpaired loop in the S1 3′UTR, led to a complete loss of viral recovery. Overall, our data provide strong experimental proof that MRV packaging signals lie at the terminal ends of the S gene segments and offer support that the sequence requirements for efficient packaging of the S1 segment include a predicted panhandle structure and specific sequences within an unpaired loop in the 3′ UTR.

Pierre-Olivier Hébert-Mercier, Francis Bergeron, N. Robert, S. Mehanovic, Kenley Joule Pierre, Raifish E. Mendoza-Villarroel, Karine de Mattos, C. Brousseau, J. Tremblay

S. Mehanovic, Raifish E. Mendoza-Villarroel, Robert S Viger, J. Tremblay

Abstract The nuclear receptor chicken ovalbumin upstream promoter–transcription factor type II (COUP-TFII)/NR2F2 is expressed in adult Leydig cells, and conditional deletion of the Coup-tfii/Nr2f2 gene impedes their differentiation. Steroid production is also reduced in COUP-TFII–depleted Leydig cells, supporting an additional role in steroidogenesis for this transcription factor. COUP-TFII action in Leydig cells remains to be fully characterized. In the present work, we report that COUP-TFII is an essential regulator of the gene encoding the anti-Müllerian hormone receptor type 2 (Amhr2), which participates in Leydig cell differentiation and steroidogenesis. We found that Amhr2 mRNA levels are reduced in COUP-TFII–depleted MA-10 Leydig cells. Consistent with this, COUP-TFII directly activates a −1486 bp fragment of the mouse Amhr2 promoter in transient transfection assays. The COUP-TFII responsive region was localized between −67 and −34 bp. Chromatin immunoprecipitation assay confirmed COUP-TFII recruitment to the proximal Amhr2 promoter whereas DNA precipitation assay revealed that COUP-TFII associates with the −67/−34 bp region in vitro. Even though the −67/−34 bp region contains an imperfect nuclear receptor element, COUP-TFII–mediated activation of the Amhr2 promoter requires a GC-rich sequence at −39 bp known to bind the specificity protein (SP)1 transcription factor. COUP-TFII transcriptionally cooperates with SP1 on the Amhr2 promoter. Mutations that altered the GCGGGGCGG sequence at −39 bp abolished COUP-TFII–mediated activation, COUP-TFII/SP1 cooperation, and reduced COUP-TFII binding to the proximal Amhr2 promoter. Our data provide a better understanding of the mechanism of COUP-TFII action in Leydig cells through the identification and regulation of the Amhr2 promoter as a novel target.

I. Shin, J. Ray, Vinayak Gupta, M. Ilgu, J. Beasley, L. Bendickson, S. Mehanovic, G. Kraus, M. Nilsen-Hamilton

We describe a ribonucleic acid (RNA) reporter system for live-cell imaging of gene expression to detect changes in polymerase II activity on individual promoters in individual cells. The reporters use strings of RNA aptamers that constitute IMAGEtags (Intracellular MultiAptamer GEnetic tags) that can be expressed from a promoter of choice. For imaging, the cells are incubated with their ligands that are separately conjugated with one of the FRET pair, Cy3 and Cy5. The IMAGEtags were expressed in yeast from the GAL1, ADH1 or ACT1 promoters. Transcription from all three promoters was imaged in live cells and transcriptional increases from the GAL1 promoter were observed with time after adding galactose. Expression of the IMAGEtags did not affect cell proliferation or endogenous gene expression. Advantages of this method are that no foreign proteins are produced in the cells that could be toxic or otherwise influence the cellular response as they accumulate, the IMAGEtags are short lived and oxygen is not required to generate their signals. The IMAGEtag RNA reporter system provides a means of tracking changes in transcriptional activity in live cells and in real time.

Reporters, I. Shin, J. Ray, V. Gupta, M. Ilgu, J. Beasley, L. Bendickson, S. Mehanovic, G. Kraus et al.

Introduction: Serum CA15-3 has been one of the most reliable tumor markers used in monitoring of breast cancer patients. To increase its sensitivity, the combined measurement of other tumor markers (CEA and ferritin) with CA15-3 was investigated. The aim of this study was determination of CA 15-3, CEA and ferritin in female patients with breast cancer, lung cancer and mastitisMethods: 300 patients with carcinoma, hospitalized at Department of Gynecologic Oncology and Department for Oncology at the University Clinics Center of Sarajevo and 200 healthy subjects were compared.Results: In patients with breast cancer the mean value of tumor markers were CEA 155.61 ng/mL, CA 15-3 106.38 U/mL and ferritin 197.03 ng/mL. In patients with lung cancer CEA was 58.97 ng/ml, CA 15-3 40.62 U/mL and ferritin 544.16 ng/mL. Patients with mastitis had CEA 5.17 ng/mL, CA 15-3 112.67 U/mL and ferritin 174.92 ng/mL. The control group had values of tumor markers CEA 1.62 ng/mL, CA 15-3 11.72 U/mL and ferritin 85.35 ng/mL. We found good correlation between CA 15-3 and CEA correlation coeffi cient was r = 0.750. There was a low correlation between CA 15-3 and ferritin with correlation coeffi cient r = 0.274.Conclusions: The CA 15-3 and CEA are useful markers in patients with confi rmed diagnosis of breast and lung cancers. The ferritin concentration has not increased in patients with breast cancer but it increased inlung patients. The future study has to make investigations of tumor markers and ferritin in different stage of breast cancer.

G. Kraus, Vinayak Gupta, Marjan Mokhtarian, S. Mehanovic, M. Nilsen-Hamilton

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