Barrett, The Honors College Thesis/Creative Project Collection
Barrett, The Honors College at Arizona State University proudly showcases the work of undergraduate honors students by sharing this collection exclusively with the ASU community.
Barrett accepts high performing, academically engaged undergraduate students and works with them in collaboration with all of the other academic units at Arizona State University. All Barrett students complete a thesis or creative project which is an opportunity to explore an intellectual interest and produce an original piece of scholarly research. The thesis or creative project is supervised and defended in front of a faculty committee. Students are able to engage with professors who are nationally recognized in their fields and committed to working with honors students. Completing a Barrett thesis or creative project is an opportunity for undergraduate honors students to contribute to the ASU academic community in a meaningful way.
Displaying 1 - 4 of 4
Description
Transient receptor potential (TRP) channels are a superfamily of ion channels found in plasma membranes of both single-celled and multicellular organisms. TRP channels all share the common aspect of having six transmembrane helices and a TRP domain. These structures tetramerize to form a receptor-activated non-selective ion channel. The specific protein being investigated in this thesis is the human transient receptor potential melastatin 8 (hTRPM8), a channel activated by the chemical ligand menthol and temperatures below 25 °C. TRPM8 is responsible for cold sensing and is related to pain relief associated with cooling compounds. TRPM8 has also been found to play a role in the regulation of various types of tumors. The structure of TRPM8 has been obtained through cryo-electron microscopy, but the functional contribution of individual portions of the protein to the overall protein function is unknown.
To gain more information about the function of the transmembrane region of hTRPM8, it was expressed in Escherichia coli (E. coli) and purified in detergent membrane mimics for experimentation. The construct contains the S4-S5 linker, pore domain (S5 and S6 transmembrane helices), pore helix, and TRP box. hTRPM8-PD+ was purified in the detergents n-Dodecyl-B-D-Maltoside (DDM), 16:0 Lyso PG, 1-Palmitoyl-2-hydroxy-sn-glycero-3-phosphoglycerol (LPPG), and 14:0 Lyso PG, 1-Myristoyl-2-hydroxy-sn-glycero-3-phosphoglycerol (LMPG) to determine which detergent resulted in a hTRPM8-PD+ sample of the most stability, purity, and highest concentrations. Following bacterial expression and protein purification, hTRPM8-PD+ was studied and characterized with circular dichroism (CD) spectroscopy to learn more about the secondary structures and thermodynamic properties of the construct. Further studies can be done with more circular dichroism (CD) spectroscopy, planar lipid bilayer (BLM) electrophysiology, and nuclear magnetic resonance spectroscopy (NMR) to gain more understanding of how the pore domain plus contributes to the activity of the whole protein construct.
To gain more information about the function of the transmembrane region of hTRPM8, it was expressed in Escherichia coli (E. coli) and purified in detergent membrane mimics for experimentation. The construct contains the S4-S5 linker, pore domain (S5 and S6 transmembrane helices), pore helix, and TRP box. hTRPM8-PD+ was purified in the detergents n-Dodecyl-B-D-Maltoside (DDM), 16:0 Lyso PG, 1-Palmitoyl-2-hydroxy-sn-glycero-3-phosphoglycerol (LPPG), and 14:0 Lyso PG, 1-Myristoyl-2-hydroxy-sn-glycero-3-phosphoglycerol (LMPG) to determine which detergent resulted in a hTRPM8-PD+ sample of the most stability, purity, and highest concentrations. Following bacterial expression and protein purification, hTRPM8-PD+ was studied and characterized with circular dichroism (CD) spectroscopy to learn more about the secondary structures and thermodynamic properties of the construct. Further studies can be done with more circular dichroism (CD) spectroscopy, planar lipid bilayer (BLM) electrophysiology, and nuclear magnetic resonance spectroscopy (NMR) to gain more understanding of how the pore domain plus contributes to the activity of the whole protein construct.
ContributorsMorelan, Danielle Taylor (Co-author) / Morelan, Danielle (Co-author) / Van Horn, Wade (Thesis director) / Chen, Julian (Committee member) / Luu, Dustin (Committee member) / Dean, W.P. Carey School of Business (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
Description
Transient receptor potential (TRP) channels are a diverse family of polymodally gated nonselective cation channels implicated in a variety of pathophysiologies. Two channels of specific interest are transient receptor potential melastatin 8 (TRPM8) and transient receptor potential vanilloid 1 (TRPV1).
TRPM8 is the primary cold sensor in humans and is activated by ligands that feel cool such as menthol and icilin. It is implicated to be involved in a variety of cancers, nociception, obesity, addiction, and thermosensitivity. There are thought to be conserved regions of structural and functional importance to the channel which can be identified by looking at the evolution of TRPM8 over time. Along with this, looking at different isoforms of TRPM8 which are structurally very different but functionally similar can help isolate regions of functional interest as well. Between TRP channels, the transmembrane domain is well conserved and thought to be important for sensory physiology. To learn about these aspects of TRPM8, three evolutionary constructs, the last common primate, the last common mammalian, and the last common vertebrate ancestor TRPM8 were cloned and subjected to preliminary studies. In addition to the initial ancestral TRPM8 studies, fundamental studies were initiated in method development to evaluate the use of biological signaling sequences to attempt to force non-trafficking membrane protein isoforms and biophysical constructs to the plasma membrane. To increase readout for these and other studies, a cellular based fluorescence assay was initiated. Eventual completion of these efforts will lead to better understanding of the mechanism that underlie TRPM8 function and provide enhanced general methods for ion channel studies.
Beyond TRPM8 studies, an experiment was designed to probe mechanistic features of TRPV1 ligand activation. TRPV1 is also a thermosensitive channel in the TRP family, sensing heat and vanilloid ligands like capsaicin, commonly found in chili peppers. This channel is also involved in many proinflammatory interactions and associated with cancers, nociception, and addiction. Better understanding binding interactions can lead to attempts to create therapeutics.
TRPM8 is the primary cold sensor in humans and is activated by ligands that feel cool such as menthol and icilin. It is implicated to be involved in a variety of cancers, nociception, obesity, addiction, and thermosensitivity. There are thought to be conserved regions of structural and functional importance to the channel which can be identified by looking at the evolution of TRPM8 over time. Along with this, looking at different isoforms of TRPM8 which are structurally very different but functionally similar can help isolate regions of functional interest as well. Between TRP channels, the transmembrane domain is well conserved and thought to be important for sensory physiology. To learn about these aspects of TRPM8, three evolutionary constructs, the last common primate, the last common mammalian, and the last common vertebrate ancestor TRPM8 were cloned and subjected to preliminary studies. In addition to the initial ancestral TRPM8 studies, fundamental studies were initiated in method development to evaluate the use of biological signaling sequences to attempt to force non-trafficking membrane protein isoforms and biophysical constructs to the plasma membrane. To increase readout for these and other studies, a cellular based fluorescence assay was initiated. Eventual completion of these efforts will lead to better understanding of the mechanism that underlie TRPM8 function and provide enhanced general methods for ion channel studies.
Beyond TRPM8 studies, an experiment was designed to probe mechanistic features of TRPV1 ligand activation. TRPV1 is also a thermosensitive channel in the TRP family, sensing heat and vanilloid ligands like capsaicin, commonly found in chili peppers. This channel is also involved in many proinflammatory interactions and associated with cancers, nociception, and addiction. Better understanding binding interactions can lead to attempts to create therapeutics.
ContributorsShah, Karan (Author) / Van Horn, Wade (Thesis director) / Neisewander, Janet (Committee member) / Biegasiewicz, Kyle (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / School of Molecular Sciences (Contributor, Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Preliminary studies indicate that the use of dietary menthol may prevent excessive weight gain through the activation of the transient receptor potential melastatin family member 8 (TRPM8) ion channel. It has also been expressed that elevation of the core temperature (Tc) inducing mild hyperthermia via an increase in ambient temperature aids in a marked reduction of the drive to eat and weight gain. While caloric restriction (CR) aims to treat obesity and secondary sicknesses, weight regain is a common result during long term weight maintenance. The goal of these studies was to evaluate and identify if the menthol and mild hyperthermia mechanisms could couple synergistically to reduce or abrogate weight gain. Ambient temperature (Ta) was increased incrementally to identify the threshold in which rodents display mild hyperthermia. Our initial attempts at hyperthermia induction failed because of limitations in the environmental chamber. These trials fail to note a threshold at which elevated Tc is sustained for any period of time. The data suggests an ambient temperature of 36-38 °C would be appropriate to induce a mild hyperthermia. A mild hyperthermia is described as the elevation of Tc 2-3 ° above the hypothalamic set point. To facilitate future hyperthermia studies, an environmental chamber was designed. A wine cooler was converted to withstand the desired temperatures, through the use of heat tape, a proportional controller, and a translucent Plexiglas custom fit door. Beyond leveraging temperature to regulate weight gain, dietary changes including a comparison between standard chow food, high fat diet, and menthol supplemented chow food treatment illustrate a strong likelihood of weight gain variability. In this pilot study, weight gain expression when given a diet supplemented with menthol (1%) showed no statistical significance relative to a high fat diet nor chow food, however, it revealed a trend of reduced weight gain. It is assumed the combination of supplemental menthol and mild hyperthermia induction will exacerbate their effects.
ContributorsJohnsson, Kailin Alexis (Author) / Van Horn, Wade (Thesis director) / Herman, Richard (Committee member) / Towe, Bruce (Committee member) / Sanford School of Social and Family Dynamics (Contributor) / School of Life Sciences (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
This study was conducted to observe the effects of varying diets on weight regain after caloric restriction. Touted as a potentially effective non-invasive treatment to obesity, caloric restriction uses the gradual decrease in caloric intake to aid in weight loss. However, once a patient is taken off caloric restriction, a marked regain of weight regain occurs, nullifying the weight loss from caloric restriction. To find ways to suppress this weight regain, this study observed the effects of four different diets: low-fat diet (chow), high-fat diet (HFD), 0.5% concentration menthol infused chow, and 1% concentration menthol infused chow. Over a span of 3 years, 43 male Sprague-Dawley rats were placed through a strict feeding protocol: 3 weeks of chow food (3.1 kcal/gram), 8 or 12 weeks of HFD (5.42 kcal/gram), and caloric restriction for 4 weeks. Separate data analysis was conducted for the year 2017-2018, due to a slightly different protocol when compared to 2018-2019 and 2019-2020.
In 2017-2018, the results showed that 0.5% menthol (n=4) suppressed weight gain more effectively than both the baseline chow diet (n=4, p=0.022) and the HFD (n=4, p=0.027). Again in 2018-2020, the 0.5% menthol (n=6) showed promising results, showing significant suppression of weight gain when compared to chow (n=13, p=0.022). Unfortunately, the difference in weight gain in 1% menthol (n=6) was inconclusive when comparing to both chow and HFD. Although 1% menthol was inconclusive in its efficacy in suppressing weight regain, the promising results on 0.5% menthol show that menthol has the potential to be an effective treatment to both prevent rapid weight gain and maintain weight loss from caloric restriction.
In 2017-2018, the results showed that 0.5% menthol (n=4) suppressed weight gain more effectively than both the baseline chow diet (n=4, p=0.022) and the HFD (n=4, p=0.027). Again in 2018-2020, the 0.5% menthol (n=6) showed promising results, showing significant suppression of weight gain when compared to chow (n=13, p=0.022). Unfortunately, the difference in weight gain in 1% menthol (n=6) was inconclusive when comparing to both chow and HFD. Although 1% menthol was inconclusive in its efficacy in suppressing weight regain, the promising results on 0.5% menthol show that menthol has the potential to be an effective treatment to both prevent rapid weight gain and maintain weight loss from caloric restriction.
ContributorsLee, Justin (Author) / Van Horn, Wade (Thesis director) / Baluch, Debra (Committee member) / Herman, Richard (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05