Blowing Chunks Cell Biology Team Julia Bowsher, North Dakota State University David Goldstein, Wright State University Sadie Hebert, University of Minnesota Mill Miller, Wright State University Lisa Montplaisir, North Dakota State University Erika Offerdahl, North Dakota State University Katie Reindl, North Dakota State University

Teachable Unit: Cell Signaling Teachable Tidbit: Perturbation of G-protein coupled receptor (GPCR) signaling by cholera toxin

Context of the Teachable Unit 200-level (sophomore) cell biology course for biology majors Prerequisite Coursework: introductory general chemistry, introductory biology Cell signaling generally taught in the second half of the course, in 2 lecture periods.

Prior Knowledge Assumed Basics of enzyme activity Cell signaling terms – Ligand – Receptor – 2 nd messenger Cell membranes are selectively permeable Extracellular signals elicit cell responses Basics of regulation – Feedback – Conformational changes – Enzyme regulation

Learning Goals Students should understand 1. how a signal is transduced, relayed, and amplified to lead to a biological response. 2. the regulation and termination of a biological signal and response.

Learning Goals Students should understand 1. how a signal is transduced, relayed, amplified to lead to a biological response. 2. the regulation & termination of a biological signal and response. Day 1 of two lecture periods would focus on Learning Goal #1.

Learning Outcomes Compare receptor mediated vs. diffusible signals Draw a model of the GPCR pathway on a diagram Order the steps in a particular transduction (receptor mediated) pathway Compare/contrast transduction systems Discriminate between genomic & non-genomic responses Describe how a message is communicated by a signal Predict how perturbing components of the pathway impacts response Analyze data to determine how cholera toxin affects cell signaling

Pre-Assessments Online quiz – Completed before class – Multiple attempts allowed Begin class with clickers and Think-Pair-Share – Based on pre-class assessment data Review student-generated models

Review the Signaling Pathway

Results in fluid loss of nearly 25 liters per day in humans. Teachable Tidbit: Introducing Cholera

“Few afflictions have attracted as much attention and impacted on as many societal and biomedical areas as cholera.” -S. Schultz, 2007 Adv. Physiol. Educ. 31:

Cholera Video Cholera Cholera

Cholera Toxin Secreted by the bacterium Vibrio cholerae Multi-subunit protein 1 alpha and 5 beta subunits 87 kDa protein tml

Effects of Cholera Toxin on Intestinal Tissue Guerrant et al. (1972) J. Infect. Diseases 125(4), 377

Generate Hypotheses Knowing what we know from the previous figure, identify 3 potential targets where cholera toxin perturbs the signaling pathway Analyze data to determine how cholera toxin affects cell signaling.

Revisit the Model What is the likely route of exposure of intestinal cells to the toxin? Indicate on your model. Analyze data to determine how cholera toxin affects cell signaling.

Effect of cholera toxin on gut ion transport Lencer et al. JCB 117:1197 (1992)

Revisit the Model Based on the previous data, can any potential targets now be eliminated as the target for cholera toxin? Analyze data to determine how cholera toxin affects cell signaling.

Effect of cholera toxin on GTPase activity Cassel and Selinger PNAS 74(8) 3307

Revisit the Model Based on the previous data, what is the likely target of cholera toxin in the GPCR pathway? Analyze data to determine how cholera toxin affects cell signaling.

Summative Assessment In-class group reflection – revisit each hypothesis generated. How do the data rule out each of your previous hypotheses OR how do the data support your previous hypotheses? Individual homework problem – give them a another signaling pathway or another agonist and ask the student to predict outcomes based on the prescribed perturbation.

Feedback from NANSI participants Numbered points refer to reviewer responses. The indented material is our responses. 1.Connection between cholera and signaling Cartoon of colon flux to connect with water flux at cell and organ level Intentionally black box cAMP stimulating Na+ and water flux -or- add it to model after discussion of Figure 1 After each graph, have a ‘processing’ or ‘debriefing’ event to ensure everyone is on the same page. Instructor must be aware of importance of students explicating and restating their hypotheses after each data slide 2.Model of signaling pathway was complex Supplement handout with animation Use clicker questions to check understanding of model 3.Receptor in handout is too generic VIP receptor 4.Is there a video for GPCR signaling

Implementation Notes 1.This is a very structured activity. Make sure you are familiar with the knowledge (aka prior knowledge) students must bring to class. 2.Transition between Cholera and cell signaling pathway needs to be carefully managed 3.Figure 1 may require significant discussion a)Directionality of H 2 0 movement b)Example or reframing using dehydration may be effective 4.Be prepared for student questions regarding the movement of the cholera toxin into the cell. 5.Embrace the messiness of the data.