This web page was produced as an assignment for Genetics 564, an undergraduate course at UW-Madison. http://genetics564.weebly.com/
Introduction
The cause of Crohn's Disease is unknown. However, a combination of genetics, environmental factors, and an impaired interaction with gut microbiota are believed to be associated with disease onset. Genetic predisposition involves genes identified through GWAS (Genome Wide Association Studies) that have been closely examined and further correlated with Crohn's. Environmental factors like vitamin D deficiency, smoking, and high sugar diets are known to increase your risk for the disease. Additionally, an impaired interaction with gut microbiota in the GI tract is associated with the inability of the immune system to distinguish healthy bacteria and pathogenic bacteria.
Many genes have been associated with the disease, however some genes have been more closely linked to Crohn's Disease than others. One gene, PTPN2, has recently been thought to have a close role with Crohn's. This gene is of particular interest because it is involved in mediating immune signaling through phosphorylation in the immune system. People with Crohn's often have mutations and differing protein expression of PTPN2.
The PTPN2 protein is highly conserved among organisms and the domains include a catalytic protein tyrosine phosphatase domain (PTPc), a coiled coil domain, and a transmembrane region. Gene ontology associated with the disease is a membrane cellular component, biological processes consisting of the immune response and glucose metabolism, and molecular function consisting of signaling and dephosphorylation activity.
PTPN2's protein interactions include proteins involved in glucose metabolism and the immune response. PTPN2's involvement in immune signaling has been heavily studied, however, its function in glucose metabolism is unclear. I plan to further study the relationship between PTPN2 and glucose metabolism. I hypothesize that PTPN2 regulates proteins involved in glucose metabolism.
Many genes have been associated with the disease, however some genes have been more closely linked to Crohn's Disease than others. One gene, PTPN2, has recently been thought to have a close role with Crohn's. This gene is of particular interest because it is involved in mediating immune signaling through phosphorylation in the immune system. People with Crohn's often have mutations and differing protein expression of PTPN2.
The PTPN2 protein is highly conserved among organisms and the domains include a catalytic protein tyrosine phosphatase domain (PTPc), a coiled coil domain, and a transmembrane region. Gene ontology associated with the disease is a membrane cellular component, biological processes consisting of the immune response and glucose metabolism, and molecular function consisting of signaling and dephosphorylation activity.
PTPN2's protein interactions include proteins involved in glucose metabolism and the immune response. PTPN2's involvement in immune signaling has been heavily studied, however, its function in glucose metabolism is unclear. I plan to further study the relationship between PTPN2 and glucose metabolism. I hypothesize that PTPN2 regulates proteins involved in glucose metabolism.
What I aim to study...
The relationship between PTPN2 and glucose metabolism using the Drosophila homolog, Ptp61F.
Aim 1: Determine if glucose metabolism genes are mis-regulated in Ptp61F mutants.
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Aim 2: Identify conserved Ptp61F interactors in regulated glucose metabolism.
After using Gene Ontology to sort my identified genes, I will use TAP-tag mass-spectrometry to identify Ptp61F interactors. I will use intestine cells and fat body cells from the Drosophila because of the intestine's role in Crohn's Disease and the fat body's (the Drosophila equivalent to the human liver) involvement in glucose metabolism. I will then identify conserved interactors between the wild-type and mutant Ptp61F in the intestine.
Aim 3: Determine which glucose metabolism pathway components Ptp61F is dephosphorylating.Ptp61F and PTPN2 are tyrosine phosphotases, therefore, they function by dephosphorylating other proteins. For this reason I will be looking for phosphorylation sites in my interacting protein from Aim 2 to discover how and where it is interacting with Ptp61F. I will use the conserved interactor found in Aim 2 to determine its phosphorylation sites that Ptp61F could potentially be dephosphorylating. I will use NetPhos 2.0 to determine the phosphorylation sites in my interactor. The program recognizes phosphorylation sites that are above the threshold. Once the phosphorylation sites were found, I would mutate the sites in vivo with the use of phosphomimetic mutations. After they were mutated, I will look at glucose levels in my constitutively phosphorylated interactor. I hypothesize that glucose levels will be increased when the interactor is constitutively phosphorylated because of Ptp61F's inability to dephosphorylate it. This rise in glucose levels will prove that Ptp61F is vital for regulation of glucose metabolism.
Using Ptp61F's STRING interaction network, I used an example glucose interactor, Chico, to see hypothetical interactions with Ptp61F. NetPhos 2.0:
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Future Directions
Transferring my research from a Drosophila model to humans will greatly progress Crohn's Disease research. A connection between PTPN2 and glucose metabolism can elucidate a connection between Diabetes and Crohn's Disease. This connection can help progress Crohn's Disease research with the use of treatment methods being used for Diabetes and apply current research with Diabetes to research for Crohn's Disease. This link can also investigate if the diagnosis of one disease could put you at risk for the other. For example, if you have Crohn's Disease are you at risk for obtaining Diabetes? No current research has made a connection between Diabetes and Crohn's Disease so this research will have great implications for the future.
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