BIO 150Intro to Biolgcl Inqry w/lab

Catalog

p53: The Guardian of the Genome. During cell division, mistakes are often made during DNA replication. If the cell is allowed to continue cell division this can lead to genomic instability and uncontrolled cell division which can lead to cancer. Therefore, the cell must have a way of correcting errors made during this process, thereby eliminating potential cancer cells from forming. One of the proteins that "protect" us from getting cancer by maintaining genome integrity is p53. p53 is a transcriptional activator protein that "turns on" genes that initiate processes such as apoptosis(programmed cell death), pauses in the cell cycle, in response to DNA damage during cell division. In a mammalian cell, p53 works by binding to short stretches of DNA called response elements that are located in front of a target gene that p53 turns on. In response to DNA damage, p53 is activated and binds to various response elements that turn on genes like p21 that pause the cell cycle. If the DNA damage is irreparable, p53 will "turn on" genes like BAX that can induce apoptosis. If the damage is reparable, p53 "turns on" genes that induces cell cycle arrest and activates proteins that repair the DNA. In this way, p53 eliminates potential cancer cells and continues the cell cycle. Because of this feature, p53 is a tumor suppressor protein known as the "guardian of the genome". Therefore, if p53 is mutated, the cell can evade cell death because of an impaired DNA damage response. This action results in cells with damaged DNA continuing through the cell cycle and can eventually lead to cancer. Furthermore, p53 is mutated in ~50-80% of all cancers. Therefore, studying the function of p53 mutants is of great importance to the cancer community and is the focus of this course. To study the action of p53 mutants, we are using Saccharomyces cerevisiae (baker's yeast) as a model system. In addition to this, this strain of yeast does not contain its own p53. Therefore, this system is ideal for studying the function of p53 and its mutants. The experimental system uses two reporter genes that qualitatively and quantitatively measure p53's ability to bind to the p21 response elements in yeast. Prerequisite: none. STAFF.