Leo1 subunit of the yeast paf1 complex binds RNA and contributes to complex recruitment

The Paf1 complex (Paf1C) affects RNA polymerase II transcription by coordinating co-transcriptional chromatin modifications and helping recruit mRNA 3' end processing factors. Paf1C cross-links to transcribed genes, but not downstream of the cleavage and polyadenylation site, suggesting that it may interact with the nascent mRNA. Paf1C purified from Saccharomyces cerevisiae binds RNA in vitro, as do the purified Leo1 and Rtf1 subunits of the complex. In vivo cross-linking and immunoprecipitation of RNA associated with Paf1C (RNA-IP) show that Leo1, but not Rtf1, is necessary for the complex to bind RNA. Cells lacking Leo1 have reduced Paf1C recruitment as well as decreased levels of histone H3 and trimethylated H3 Lys(4) within transcribed chromatin. Together, these results suggest that association of Paf1C with RNA stabilizes its localization at actively transcribed regions where it influences chromatin structure.

Abstract B178: Nanoscale quantification of phosphorylated and unphosphorylated ERK and MEK isoforms differentiates tumor and nontumor clinical specimens

The MAP Kinase pathway is commonly dysregulated in cancer. We have developed the use of a highly sensitive microfluidic nano-immunoassay system (NIA) to perform detailed analysis of ERK and MEK activation in hematopoietic and solid tumors. We recently reported use of NIA for measurement of proteins in as little as 4 nanoliters of lysate from preclinical and clinical lymphoma and leukemia specimens (Fan et al, Nature Medicine 2009). Now, we present results measuring specific isoforms of MAP Kinase proteins in cells sampled from patients with solid tumors and Myelodysplastic Syndrome (MDS). First, we developed tissue collection, handling and processing protocols to produce reliable NIA results in a small number of cells obtained by minimally invasive techniques. We collected over 100 blood buffy coat and fine needle aspirate (FNA) specimens from normal controls and patients with MDS or solid tumors. Using a single antibody that recognizes both the phosphorylated and unphosphorylated isoforms of ERK, we can determine not only relative levels of phosphorylated isoforms of ERK protein, but also calculate the percent phosphorylation of ERK in each clinical specimen. We have developed a similar method to quantify MEK isoforms. NIA revealed that adenocarcinoma, squamous cell carcinoma, renal cell carcinoma, and MDS samples could be distinguished from non-tumor specimens based upon different patterns of phosphorylated ERK isoforms. To determine if signaling changes can be detected by NIA upon treatment of cells with novel targeted therapies, human leukemic TF1 cells were treated with a polo-1 kinase (PLK-1) inhibitor, ON01910 (Onconova, Inc.). We found the surprising result that only 5% of ERK1 and ERK2 were found to be phosphorylated in the TF1 cell line, whereas 45% and 90% of MEK1 and MEK2 were phosphorylated, respectively. Additionally, NIA analysis revealed a 20% decrease in the percent of phosphorylated MEK2 after treatment with ON01910. Taken together, our studies demonstrate that NIA can be used to identify specific changes in MAPK signaling pathway that distinguish normal from malignant cells as well as quantitatively measure the response of malignant cells to a targeted therapeutic.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B178.

Unphosphorylated SR-like protein Npl3 stimulates RNA polymerase II elongation

The production of a functional mRNA is regulated at every step of transcription. An area not well-understood is the transition of RNA polymerase II from elongation to termination. The S. cerevisiae SR-like protein Npl3 functions to negatively regulate transcription termination by antagonizing the binding of polyA/termination proteins to the mRNA. In this study, Npl3 is shown to interact with the CTD and have a direct stimulatory effect on the elongation activity of the polymerase. The interaction is inhibited by phosphorylation of Npl3. In addition, Casein Kinase 2 was found to be required for the phosphorylation of Npl3 and affect its ability to compete against Rna15 (Cleavage Factor I) for binding to polyA signals. Our results suggest that phosphorylation of Npl3 promotes its dissociation from the mRNA/RNAP II, and contributes to the association of the polyA/termination factor Rna15. This work defines a novel role for Npl3 in elongation and its regulation by phosphorylation.

Occupational therapy students' perspectives on occupation as an agent that promotes healthful lifestyles

OBJECTIVES

This study was conducted to determine occupational therapy students' perspectives on occupation as an agent that promotes healthful lifestyles, what factors influence these perspectives, and the extent to which formal classroom instruction in occupation as a health-promoting agent influenced their perspective transformation.

METHOD

Through a precourse and postcourse survey, weekly log sheets, and audiotaped class discussions, data regarding attitudes and beliefs about health promotion were collected from 23 occupational therapy master's students enrolled in the course Wellness Through Occupation. The data were analyzed with a priori concept coding to determine whether perspective transformation occurred as a result of formal classroom instruction.

RESULTS

Participants indicated that family values, previous formal and informal instruction, and personal experience were the major factors that influenced their perspectives on occupation as an agent that promotes a healthful lifestyle. The results demonstrated that participants had a perspective transformation, which is the first step in the behavioral change process.

CONCLUSION

Formal classroom instruction can be a factor in promoting healthful lifestyles through occupation. Such instruction can be an important step in empowering people to take responsibility for their own health.