Joni Seeling

Faculty Mentor: Joni Seeling, Assistant Professor, Department of Biological Sciences

Student Team Members:
Stacy Batres, Amanda Means, & Grayson Means

Funding provided by the College of Sciences Dean’s Office

Student Reflections

Faculty Report

Cells in our body communicate with one another through signaling molecules. Wnt is a signaling molecule that is a key regulator of embryogenesis and cancer. Colon cancer is the second leading cause of cancer deaths in the U.S., and Wnt pathway overactivity is an early event in most, if not all, colon cancers. Wnt is also frequently upregulated in lung, breast, and skin cancer. The Wnt pathway is highly conserved, and much of the pathway has been characterized in studies using the frog Xenopus laevis. Because of pathway conservation, information gained in Xenopus is applicable to the Wnt pathway in humans. Protein phosphatase 2A (PP2A) is an abundant serine/threonine phosphatase that modulates signaling pathways important in embryogenesis and cancer, most frequently in an inhibitory fashion. My lab previously found that PP2A modulates Wnt signaling. My current research characterizes the regulation of Wnt signaling by PP2A in frogs, and translates this information to the regulation of Wnt in human cancer. A clearer understanding of how B56 subunits modulate Wnt signaling will allow us to better understand colon tumorigenesis and may lead to innovative approaches for the treatment and prevention of one of the most deadly cancers.

Three undergraduate students, Grayson Means, Stacy Batres, and Amanda Means, carried out research in my lab during the summer of 2014 funded by the Summer 2014 Faculty and Student Team (FAST) Award. Grayson, Stacy, and Amanda are also continuing their research through the 2014-2015 academic year. One procedure that each student must master to study the Wnt pathway in frogs is embryo microinjection. Microinjection allows one to modify the content of an embryo, in our case changing PP2A activity, and then determine what affects this has on the embryos as they develop. The procedure involves making a glass needle to hold the substance to be microinjected, and then positioning and calibrating the needle to microinject embryos. To test their microinjection abilities, students microinject Wnt RNA, which induces the formation of a secondary body axis, i.e., a secondary head. This phenotype provides a clear measurement of microinjection success; each microinjected embryo should have some degree of a secondary head in a successful microinjection. Once a student has mastered this technique, they then microinject their specific factor to modify PP2A activity, and determine what affect this has on body axis formation and therefore also Wnt pathway activity.

Grayson’s project involves determining if loss of PP2A inhibits body axis elongation that occurs as an embryo develops from a sphere-shaped embryo into a tadpole. This involves removing a portion of the embryo (an explant) by microdissection and determining if PP2A microinjection prevents elongation of that explant. Grayson has mastered the microdissection technique, and is currently working on his microinjections so that he can determine if changes in PP2A activity affect body axis elongation.

Stacy is analyzing how two very similar B56 proteins can either inhibit (B56a) or activate (B56e) Wnt signaling. This involves first making chimeras of these two proteins, containing different regions of each gene, and then determining if these chimeric proteins inhibit or activate Wnt signaling. Stacy completed one chimera this summer, and she is continuing to make a second chimera. She is also practicing microinjection so that she can microinject her chimeras and analyze body axis formation in the resulting embryos to determine whether the chimeras inhibit or activate Wnt signaling.

Amanda is our lead frog surgeon and over the summer she has perfected her testes- removal surgeries, which provide sperm for in vitro fertilizations to generate embryos. She has carried out twelve survival surgeries. B56d/g and B56g/g are two alternative products that are synthesized from the B56g gene. Amanda has been quite successful with her Wnt RNA microinjections, and soon she will modulate B56d/g and B56g/g expression by microinjections to determine if these isoforms have distinct roles in Wnt signaling.