Oogenesis and embryogenesis require the precise orchestration of multiple signaling networks and molecular pathways. Perturbations in any one event can lead to a host of developmental abnormalities such as the Apert and Pfieffer syndromes and cancer. Among the crucial components are the RAS-extracellular regulated kinase (ERK) signaling pathway and Dicer and Drosha, essential mediators of small RNA biogenesis. They govern a wide array of cellular and developmental processes, including many critical aspects of oogenesis and embryogenesis. For example, in mice, loss of ERK signaling results in defective oocyte maturation and perturbed trophoblast development, while in Caenorhabditis elegans loss of ERK function disrupts oocyte differentiation and maturation, leading to sterility or early embryonic lethality. Similarly, in C. elegans and mice, loss of Dicer or Drosha disrupts oocyte meiotic maturation and embryonic development, respectively. However, the functional intersection between the RAS/ERK pathway and small RNA biogenesis remains unclear, and no studies have shown that the RAS/ERK pathway regulates the activity of Dicer or Drosha. Our work on the identification of substrates through which ERK governs germline development in Caenorhabditis elegans recently uncovered a direct, functional link between the RAS/ERK pathway and Dicer and Drosha. In a functional genomics screen, we identified Dicer and Drosha as novel, evolutionarily conserved substrates of ERK that each function in a reciprocally antagonistic manner with ERK. By generating antibodies specific to the phosphorylated form of Dicer, we also observed that ERK-mediated phosphorylation of Dicer induces it to translocate from the cytoplasm to the nucleus in the C. elegans germline;this phosphorylation event and its consequences on Dicer localization are conserved in mouse embryonic fibroblasts and human tumor cells. Therefore, the goals of our proposed study are three-fold: i) to elucidate the effect of ERK-dependent phosphorylation on the localization of Drosha;ii) to test the impact of ERK-mediated phosphorylation on Dicer and Drosha function and small RNA production;and, iii) to determine the mechanistic basis of phospho-Dicer function by identifying functional partners of the modified proteins. Given the general relevance of RAS/ERK signaling pathway and Dicer and Drosha, results from our work will likely inform multiple systems, including human oogenesis and oncogenesis. !

Public Health Relevance

This proposed project aims to investigate the role of the oncogenic RAS/Extracellular-signal regulated kinase (ERK) in regulating the tumor suppressors Dicer and Drosha, two key small RNA biogenesis enzymes. The study integrates multiple approaches ranging from classical genetics and cell biology to genomic and proteomic methods to assess the impact of ERK mediated phosphorylation on Dicer and Drosha function in vivo during Caenorhabitis elegans germline development. !

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM098200-02
Application #
8323245
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Haynes, Susan R
Project Start
2011-09-01
Project End
2016-08-31
Budget Start
2012-09-01
Budget End
2013-08-31
Support Year
2
Fiscal Year
2012
Total Cost
$297,040
Indirect Cost
$109,040
Name
University of Texas MD Anderson Cancer Center
Department
Genetics
Type
Other Domestic Higher Education
DUNS #
800772139
City
Houston
State
TX
Country
United States
Zip Code
77030
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Drake, Melanie; Furuta, Tokiko; Suen, Kin Man et al. (2014) A requirement for ERK-dependent Dicer phosphorylation in coordinating oocyte-to-embryo transition in C. elegans. Dev Cell 31:614-28
Berkseth, Matt; Ikegami, Kohta; Arur, Swathi et al. (2013) TRA-1 ChIP-seq reveals regulators of sexual differentiation and multilevel feedback in nematode sex determination. Proc Natl Acad Sci U S A 110:16033-8
Suen, Kin Man; Lin, Chi-Chuan; George, Roger et al. (2013) Interaction with Shc prevents aberrant Erk activation in the absence of extracellular stimuli. Nat Struct Mol Biol 20:620-7
Lopez 3rd, Andrew L; Chen, Jessica; Joo, Hyoe-Jin et al. (2013) DAF-2 and ERK couple nutrient availability to meiotic progression during Caenorhabditis elegans oogenesis. Dev Cell 27:227-40