Karl Obrietan, Ph.D.
Associate Professor
Department of Neuroscience
Degree: Stanford University
Postdoctoral Training: University of Washington
Contact Information
4123 Graves Hall
333 W. 10th Avenue
Columbus, OH 43210
PHONE: (614) 292-4432
FAX: (614) 688-8742
E-MAIL: obrietan.1@osu.edu
Link to NLM PubMed publications list for Karl Obrietan (last 10 years)
Research Area:
Second messenger signaling and transcriptional pathways that regulate circadian timing: Ca2+, CREB and neuronal plasticity: peptidergic modulation of glutamatergic signaling.
Current Research:
Circadian rhythms of behavior and physiology are observed in a variety of organisms. In mammals, the suprachiasmatic nuclei (SCN) of the hypothalamus function as the major biological clock. The inherent pacemaker activity of the SCN can be effectively regulated by changes in the environmental light cycle. This allows an animal to synchronize its internal clock with the ever-changing light cycle encountered over a seasonal/yearly basis. What are the cellular events that underlie both the generation of a biological rhythm and the ability of light to affect clock timing? Recent work has revealed that coordinated transcriptional oscillations are required for circadian rhythm generation and that light-activated signaling events entrain the clock by resetting transcriptional rhythms. Given these observations, a characterization of the intracellular signaling pathways and downstream transcription factors activated by light will be critical for understanding the functional propertie! s of the circadian clock.
My laboratory examines how signaling through the mitogen-activated protein kinase (MAPK) signal transduction pathway and transcription mediated by the cAMP response element (CRE) affect circadian timing. Recent data reveal that exposure to light during the subjective night triggers activation of the MAPK pathway in the SCN. This contrasts with exposure during the subjective day, where light does not significantly increase MAPK signaling.
In addition, stimulation of MAPK-dependent signaling leads to phospho-activation of the transcription factor CREB and to activation of CRE-mediated gene expression. Current studies at a behavioral and molecular level focus on how signaling events downstream of the MAPK pathway and the CREB/CRE transcriptional pathway may regulate circadian timing.
Techniques:
- Molecular: Western blotting, Northern blotting, PCR
- Cell Biology: Primary neuronal culture, transfection, site-directed mutagenesis
- Surgical: small animal surgery
- Behavioral: behavioral assays
- Microscopy: digital fluorescent microscopy
- Other: transcriptional assays, kinase assays, immunohistochemistry
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