The mammalian suprachiasmatic nuclei (SCN) coordinates organismic function with the diurnal light/dark cycle. My laboratory investigates 1) functional organization of the circadian timing system and mechanisms of glutamatergic signaling in the SCN, and 2) functions of circadian clock genes in peripheral tissues, specifically their roles in regulating cellular responses to environmental toxins and in carcinogenesis.

Glutamatergic Regulation of SCN Neurons
This project focuses on glutamatergic signal transduction. Specifically, we are interested in mechanisms that allow SCN neurons to survive excitotoxic stress. This project focuses on the role of circadian clock state and intracellular calcium regulation of downstream targets that include caspases, anti-apoptotic factors and core clock components.

Effects of Dioxins on Circadian Timing Mechanisms
Persistent activation of AhR by dioxins disrupts liver and reproductive function, and causes multi-site carcinogenesis.
We hypothesize that dysregulation of circadian clock genes underlies pathologies associated with dioxin exposure. We are exploring regulation of the circadian clock genes, Per1 and Per2, by AhR in reproductive tissues (GnRH neurons and ovarian granulosa cells) and in tumor cells.


Recent Publications

Tischkau SA.  2011.  AhR and the Circadian Clock. In:  The Aryl Hydrocarbon Receptor in Biology and Toxicology, R. Pohjanrihva, ed.

Tischkau SA, Howell RA, Hickok JR, Krager SL, and Bahr JM.  2011.  The luteinizing hormone surge regulates circadian clock gene expression in the chicken ovary.  Chronobiol. Int. 28(1):10-20.  PMID: 21182400.

Tischkau SA, Jaeger CD, and Krager SL.  2011.  Circadian clock disruption in the mouse ovary in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin.  Toxicol. Lett. 201:116-122.  PMID: 21182907

Karmarkar SW, Bottum KM, Krager SL, and Tischkau SA. 2011. ERK/MAPK Is Essential for Endogenous Neuroprotection in SCN2.2 Cells. PLoS ONE 6(8): e23493. doi:10.1371/journal.pone.0023493

Wang C, CX Xu, SL Krager, KM Bottum, DF Liao and SA Tischkau.  2011.  Aryl hydrocarbon receptor deficiency enhances insulin sensitivity and regulates PPAR-α pathway in mice.  Environmental Health Perspectives. 119:1739-44.

Tischkau SA, RA Howell, JR Hickok, SL Krager and JM Bahr.  2011.  The luteinizing hormone surge regulates circadian clock gene expression in the chicken ovary.  Chronobiol. Int. 28(1):10-20.  PMID: 21182400.

Tischkau SA, CD Jaeger and SL Krager.  2011.  Circadian clock disruption in the mouse ovary in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin.  Toxicol. Lett. 201:116-122.  PMID: 21182907

Karmarkar SW, SL Krager, KM Bottum and SA Tischkau. 2011.  ERK/MAPK as a neuroprotective agent in suprachiasmatic nucleus neurons.  PLoS One (In Press).

Wang C, CX Xu, SL Krager, KM Bottum, DF Liao and SA Tischkau.  2011.  Aryl hydrocarbon receptor deficiency enhances insulin sensitivity and regulates PPAR-α pathway in mice.  Environmental Health Perspectives (In press)

. Xu CX, DF Liao and SA Tischkau.  2011. Aryl Hydrocarbon Receptor Activation Represses Light-Induced Phase Resetting of the Circadian Clock through Inhibition CRE-Element Activity on the Per1 Promoter. (In preparation for submission to Journal of Biological Chemistry).

Krager SL, SW Karmarkar, KM Bottum and SA Tischkau.  2011.  Caspase activation after excitotoxic insult in suprachiasmatic nucleus neurons.  (In preparation for submission to Brain Research).

Tischkau SA, RA Trammell and LA Toth. 2011. Impact of sleep disruption on clock gene expression, cellular stress and inflammation in lung.  (In preparation for submission to PLoS One).  

Karmarkar SW, SL Krager, JA Cohen, JT Stark, SA Tischkau and KM Bottum. 2011.  Caspase activation and MAPK pathways are important in endogenous neuroprotection in suprachiasmatic nucleus neurons.  Annual Meeting of the American Stroke Association.  Los Angeles, CA.

Karmarkar SW, SL Krager, KM Bottum and SA Tischkau. 2011.  Mechanisms of neuroprotection in the SCN2.2 neurons.  University of Illinois at Springfield.  11th Annual Research Symposium.  Note: SW Karmarkar won 1st place in the oral presentation category for this work.

Karmarkar SW, SL Krager, KM Bottum and SA Tischkau. 2011.  Mechanisms of neuroprotection in the SCN2.2 neurons.  Southern Illinois University School of Medicine.  22nd Annual Research Symposium.  Note: SW Karmarkar won 1st place in the oral presentation category for this work.