Joanne Kamens

Publications (18) View all

• Article: Potent and systematic RNAi mediated silencing with single oligonucleotide compounds.

  Jennifer Lapierre, William Salomon, James Cardia, Karen Bulock, Jessica T Lam, William J Stanney, Glenna Ford, Bernice Smith-Anzures, Tod Woolf, Joanne Kamens, Anastasia Khvorova, Dmitry Samarsky
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  ABSTRACT: RNA interference (RNAi) has been established as an important tool for functional genomics studies and has great promise as a therapeutic intervention for human diseases. In mammalian cells, RNAi is conventionally induced by 19-27-bp RNA duplexes generated by hybridization of two complementary oligonucleotide strands (oligos). Here we describe a novel class of RNAi molecules composed of a single 25-28-nucleotide (nt) oligo. The oligo has a 16-nt mRNA targeting region, followed by an additional 8-10 nt to enable self-dimerization into a partially complementary duplex. Analysis of numerous diverse structures demonstrates that molecules composed of two short helices separated by a loop can efficiently enter and activate the RNA-induced silencing complex (RISC). This finding enables the design of highly effective single-oligo compounds for any mRNA target.
  RNA 06/2011; 17(6):1032-7. · 5.09 Impact Factor
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  Available from: Joanne Kamens

  Article: Modified dsRNAs that are not processed by Dicer maintain potency and are incorporated into the RISC.

  William Salomon, Karen Bulock, Jennifer Lapierre, Pamela Pavco, Tod Woolf, Joanne Kamens
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  ABSTRACT: Chemical modification of RNA duplexes can provide practical advantages for RNA interference (RNAi) triggering molecules including increased stability, safety and specificity. The impact of nucleotide modifications on Dicer processing, RISC loading and RNAi-mediated mRNA cleavage was investigated with duplexes >or=25 bp in length. It is known that dsRNAs >or=25 bp are processed by Dicer to create classic 19-bp siRNAs with 3'-end overhangs. We demonstrate that the presence of minimal modification configurations on longer RNA duplexes can block Dicer processing and result in the loading of the full-length guide strand into RISC with resultant mRNA cleavage at a defined site. These longer, modified duplexes can be highly potent gene silencers, with EC50s in the picomolar concentration range, demonstrating that Dicer processing is not required for incorporation into RISC or potent target silencing.
  Nucleic Acids Research 02/2010; 38(11):3771-9. · 8.03 Impact Factor
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  Available from: Joanne Kamens

  Article: cis-Element clustering correlates with dose-dependent pro- and antisignaling effects of IL18.

  D Leyfer, A Bond, E Tworog, D Perron, S Maska, A Brito, J Kamens, Z Weng, J Voss
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  ABSTRACT: We examine the effects of IL18 on monocytes by performing microarray experiments using cell line KG1. Based on sensitivity to IL18, we identified three functionally distinct gene expression clusters (EC). We see little proinflammatory gene induction at low IL18 concentrations, but instead observe induction of diverse NF kappa B signaling inhibitors. Conversely, intermediate concentrations of IL18 induced proinflammatory genes including the activating subunits of NF kappa B. At the highest IL18 concentration, we observe a third gene cluster containing the proapoptotic Fas gene among others. Clustering of IL18-responsive genes based on cis-elements in their promoters agreed well with the ECs. We conclude that IL18 produces a dose-dependent transcriptional response that can in part be attributed to the composition of cis-elements in the promoters of IL18-responsive genes. These results also support a model for regulatory mechanisms that prevent spurious immune response due to weak cytokine fluctuations and a separate mechanism enabling induction of proinflammatory functions by higher levels of cytokine.
  Genes and Immunity 09/2004; 5(5):354-62. · 3.87 Impact Factor
• Article: Direct phosphorylation of NF-kappaB1 p105 by the IkappaB kinase complex on serine 927 is essential for signal-induced p105 proteolysis.

  A Salmerón, J Janzen, Y Soneji, N Bump, J Kamens, H Allen, S C Ley
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  ABSTRACT: The p105 precursor protein of NF-kappaB1 acts as an NF-kappaB inhibitory protein, retaining associated Rel subunits in the cytoplasm of unstimulated cells. Tumor necrosis factor alpha (TNFalpha) and interleukin-1alpha (IL-1alpha) stimulate p105 degradation, releasing associated Rel subunits to translocate into the nucleus. By using knockout embryonic fibroblasts, it was first established that the IkappaB kinase (IKK) complex is essential for these pro-inflammatory cytokines to trigger efficiently p105 degradation. The p105 PEST domain contains a motif (Asp-Ser(927)-Gly-Val-Glu-Thr), related to the IKK target sequence in IkappaBalpha, which is conserved between human, mouse, rat, and chicken p105. Analysis of a panel of human p105 mutants in which serine/threonine residues within and adjacent to this motif were individually changed to alanine established that only serine 927 is essential for p105 proteolysis triggered by IKK2 overexpression. This residue is also required for TNFalpha and IL-1alpha to stimulate p105 degradation. By using a specific anti-phosphopeptide antibody, it was confirmed that IKK2 overexpression induces serine 927 phosphorylation of co-transfected p105 and that endogenous p105 is also rapidly phosphorylated on this residue after TNFalpha or IL-1alpha stimulation. In vitro kinase assays with purified proteins demonstrated that both IKK1 and IKK2 can directly phosphorylate p105 on serine 927. Together these experiments indicate that the IKK complex regulates the signal-induced proteolysis of NF-kappaB1 p105 by direct phosphorylation of serine 927 in its PEST domain.
  Journal of Biological Chemistry 07/2001; 276(25):22215-22. · 4.77 Impact Factor
• Article: PRAM-1 is a novel adaptor protein regulated by retinoic acid (RA) and promyelocytic leukemia (PML)-RA receptor alpha in acute promyelocytic leukemia cells.

  C Moog-Lutz, E J Peterson, P G Lutz, S Eliason, F Cavé-Riant, A Singer, Y Di Gioia, S Dmowski, J Kamens, Y E Cayre, G Koretzky
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  ABSTRACT: The t(15;17) translocation, found in 95% of acute promyelocytic leukemia, encodes a promyelocytic leukemia (PML)-retinoic acid receptor alpha (RARalpha) fusion protein. Complete remission of acute promyelocytic leukemia can be obtained by treating patients with all-trans retinoic acid, and PML-RARalpha plays a major role in mediating retinoic acid effects in leukemia cells. A main model proposed for acute promyelocytic leukemia is that PML-RARalpha exerts its oncogenic effects by repressing the expression of retinoic acid-inducible genes critical to myeloid differentiation. By applying subtraction cloning to acute promyelocytic leukemia cells, we identified a retinoic acid-induced gene, PRAM-1 (PML-RARalpha target gene encoding an Adaptor Molecule-1), which encodes a novel adaptor protein sharing structural homologies with the SLAP-130/fyb adaptor. PRAM-1 is expressed and regulated during normal human myelopoiesis. In U937 myeloid precursor cells, PRAM-1 expression is inhibited by expression of PML-RARalpha in the absence of ligand and de novo superinduced by retinoic acid. PRAM-1 associates with other adaptors, SLP-76 and SKAP-55HOM, in myeloid cell lines and with protein tyrosine kinase lyn. By providing the first evidence that PML-RARalpha dysregulates expression of an adaptor protein, our data open new insights into signaling events that are disrupted during transformation by PML-RARalpha and induced by retinoic acid during de novo differentiation of acute promyelocytic leukemia cells.
  Journal of Biological Chemistry 07/2001; 276(25):22375-81. · 4.77 Impact Factor