Browsing by Subject "Phosphate"

Inositol phosphates (IPs) are eukaryotic signaling molecules that play important roles in a wide range of biological processes. IPs are required for embryonic development and patterning, insulin secretion, the regulation of telomere length, proper progression through the cell cycle, and the regulation of ion channels. This work uses the yeast Saccharomyces cerevisiae as a model system for investigating the functions of IPs and focuses on the transcriptional regulation of the gene encoding the secreted mating pheromone MFα2 by the IP kinase Ipk2 (also called Arg82, ArgR3, and IPMK). This work shows that Ipk2 has both kinase-dependent and kinase-independent functions in regulating the transcription of MFα2. Transcription of MFα2 is also dependent upon the integrity of an Mcm1-binding site in its promoter. This is the first description of a role for this binding site in the transcription of MFα2.

In vivo and in vitro screening approaches to identify additional factors associated with MFα2 expression or with IP biology generally are also described. These unbiased approaches provide some valuable insight for further investigations.

Roots are developmentally plastic and highly dependent on the immediate environment. By studying root responses to abiotic stress, we have identified novel regulators of developmental modulation. When roots are deprived of phosphate (Pi), developmental programs are modulated to slow primary root growth and expand surface area through emergence of root hairs. By focusing on exposure time-periods of less than two days, we have described very early changes to root development in response to this condition that may reveal new mechanisms of root hair specification and emergence. Also, using transcriptomic analyses with high spatial resolution, we identified a kinase that is specifically induced in root vascular tissue within three hours of exposure and acts to modulate aspects of root development in response to deprivation of Pi. These data suggest that individual tissues play unique roles in whole organ development, and that interpretation of Pi -deprivation responses may change as we develop methods with resolution necessary to understand these roles. Beyond Pi, we compared transcriptomic data for four additional stresses and identified a novel stress-responsive transcription factor that modulates expression of a cell expansion protein. This putative network connection demonstrates the value of using high-dimensional data for inference of regulatory relationships. Overall, we have combined "-omics" approaches with reverse genetics to identify novel developmental regulators and described a phenotypic frame-work with resolution at which cellular mechanisms can be studied.