Poster abstracts
Poster number 49 submitted by Allison Webb
EGL-38/PAX functions in communicating cells of the Caenorhabditis elegans egg-laying system to coordinate signaling and differentiation
Allison Webb (OSBP), Ryan Johnson (OSU Molecular Genetics), Helen Chamberlin (OSU Molecular Genetics)
Abstract:
Paired-box (Pax) transcription factors are essential regulators of coordinated development responsible for controlling the growth and differentiation of diverse cells into organ systems. Pax transcription factors rely on cellular context to initiate their cell-specific activity through poorly understood mechanisms. To investigate PAX function, we are utilizing the PAX2/5/8 Caenorhabditis elegans ortholog EGL-38 as a simplified model system. EGL-38 functions in the hermaphrodite egg-laying system to coordinate anchoring of the vulva to the uterus. To initiate creation of this vulval-uterine connection, a LIN-3/Epidermal Growth Factor (EGF) signal is sent from the vulval vulF cells to the LET-23/EGFR receptor on a subset of neighboring uterine cells. These cells are specified as uv1 and are characterized by non-migration and by expression of the neuropeptide nlp-2. EGL-38 is required for lin-3/egf expression in the vulF cells (1,2), thereby initiating this signaling pathway. EGL-38 may function in response to the LIN-3/EGF pathway in the uv1 cells, as we have confirmed that EGL-38 can bind the nlp-2 promoter in vitro, and that both uv1 non-migration and nlp-2 expression are significantly decreased in egl-38 mutants as well as in lin-1 mutants. LIN-1 is an ETS-family transcription factor; ETS proteins often serve as PAX co-factors to confer DNA binding specificity (3). To identify if an interaction with LIN-1 is the source of EGL-38 cell-specificity, we are investigating LIN-1 and its role in the creation of the vulval-uterine connection. We have discovered that a loss-of-function mutation in lin-1 significantly decreases lin-3 expression in the vulF cells, and further experiments are being conducted to examine the in vivo interaction of EGL-38 and LIN-1. Additionally, we are investigating the activation and role of EGL-38 in the uv1 cells to determine how PAX proteins may function discriminately in communicating cells.
References:
1. Rajakumar V and Chamberlin HM. 2007. “The Pax2/5/8 gene egl-38 coordinates organogenesis of the C. elegans egg-laying system.” Developmental Biology 301(1):240-253. PMID: 17020758
2. Chang C, et al. 1999. “Reciprocal EGF signaling back to the uterus from the induced C. elegans vulva coordinates morphogenesis of epithelia.” Current Biology 9(5):237-246. PMID: 10074449
3. Fitzsimmons D, et al. 2001. “Highly conserved amino acids in Pax and Ets proteins are required for DNA binding and ternary complex assembly.” Nucleic Acids Research 29(20):4154-4165. PMID: 11600704
Keywords: coordinated development, signaling, cell-specificity