Faculty Mentor

Rebecca Prosser

Department (e.g. History, Chemistry, Finance, etc.)

Biochem/Cellular/Molecular Bio

College (e.g. College of Engineering, College of Arts & Sciences, Haslam College of Business, etc.)

Arts and Sciences

Year

2015

Abstract

Mammalian circadian rhythms are controlled by a central pacemaker located in the suprachiasmatic nucleus (SCN) of the brain. The SCN exhibits endogenous rhythms in neuronal activity and entrains to external stimuli, particularly light. Interestingly, phase shifts in response to light only occur at night and the mechanisms gating phase shifting are not well characterized. Our lab demonstrated that the extracellular protease, tissue-type plasminogen activator (tPA) and its inhibitor, plasminogen activator inhibitor (PAI-1), help gate phase shifting. Total tPA and PAI-1 expression are rhythmic in mouse SCN. These proteins mediate different functions depending on their exact subcellular localization. Therefore, knowing where they are located within the SCN will clarify their actions with respect to SCN clock phase regulation. The immortalized rat SCN2.2 cell culture exhibits rhythms in protein expression in vitro that mirror those found in vivo and can be separated into cellular, extracellular matrix, and media fractions. Here, we investigate tPA and PAI-1 expression using western blotting in the cellular fraction of the SCN2.2 line over a 36-hr timecourse. Preliminary results suggest a rhythm of PAI-1 levels inside the cell with peak expression in the early subjective night. Future studies are aimed toward elucidating the subcellular localization and temporal expression patterns of these proteins in the SCN.

Share

COinS
 

Circadian Rhythmic Localization of tPA and PAI-1 in the SCN 2.2 Cell Culture May Provide Evidence for Determining the Mechanism of Gating Photic Phase Shifts

Mammalian circadian rhythms are controlled by a central pacemaker located in the suprachiasmatic nucleus (SCN) of the brain. The SCN exhibits endogenous rhythms in neuronal activity and entrains to external stimuli, particularly light. Interestingly, phase shifts in response to light only occur at night and the mechanisms gating phase shifting are not well characterized. Our lab demonstrated that the extracellular protease, tissue-type plasminogen activator (tPA) and its inhibitor, plasminogen activator inhibitor (PAI-1), help gate phase shifting. Total tPA and PAI-1 expression are rhythmic in mouse SCN. These proteins mediate different functions depending on their exact subcellular localization. Therefore, knowing where they are located within the SCN will clarify their actions with respect to SCN clock phase regulation. The immortalized rat SCN2.2 cell culture exhibits rhythms in protein expression in vitro that mirror those found in vivo and can be separated into cellular, extracellular matrix, and media fractions. Here, we investigate tPA and PAI-1 expression using western blotting in the cellular fraction of the SCN2.2 line over a 36-hr timecourse. Preliminary results suggest a rhythm of PAI-1 levels inside the cell with peak expression in the early subjective night. Future studies are aimed toward elucidating the subcellular localization and temporal expression patterns of these proteins in the SCN.

 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.