Associate Member, Department of Molecular and Cellular Biology

Roswell Park Cancer Institute
Elm and Carlton Streets
Buffalo NY 14263
Tel:       716-845-3429
Fax:      716-845-8389
E-mail: marina.antoch@roswellpark.org

Education

MS, Biochemistry/Molecular Biology, Moscow State University, Moscow, Russia, 1978
PhD, Biochemistry/Molecular Biology, Moscow State University, Moscow, Russia, 1989

Area of General Research Interest

• Mechanism of circadian clock function
• Role of circadian clock genes in modulating response to cancer therapy
• Non-circadian function of clock genes

Current Program

• Role of posttranslational modifications in functional regulation of clock proteins
• Mechanism of transcriptional activation/repression by major circadian CLOCK/BMAL1 complex
• Mechanisms of circadian output signaling
• Role of circadian clock genes in controlling the sensitivity to genotoxic stress
• Search for pharmacological modulators of the CLOCK/BMAL1 transcriptional activity

Brief Description

It is well established now that a broad variety of organisms display circadian rhythms (i.e. oscillations with 24-hr periodicities) in many aspects of their behavior, physiology and metabolism. These rhythms are generated endogenously and function under genetic control. In mammals, the basic molecular oscillator consists of two transcriptional activators - CLOCK and BMAL1 - and their transcriptional targets, CRYPTOCHROMES (CRYs) and PERIODS (PERs), which function as negative regulators of the CLOCK/BMAL1 activity, thus forming the major circadian autoregulatory feedback loop. Our laboratory is interested in understanding the molecular mechanisms determining CLOCK/BMAL1 transcriptional activity and suppression of this activity by CRY proteins. Thus, we have demonstrated that CLOCK and BMAL1 interaction triggers their posttranslational modification (phosphorylation), which plays an important role in determining the intracellular distribution, stability and functional activity of the transcriptional complex. We also examined the effect of CRY proteins on posttranslational modifications and intracellular distribution of CLOCK/BMAL1 and found that CRYs induce stabilization and nuclear accumulation of unphosphorylated and accordingly transcriptionally inactive forms of the proteins. These findings identify CRY as a factor that reverts the function of CLOCK/BMAL1 complex by converting it from a transactivating into a transrepressing one. Based on these data, we proposed a modified model of the circadian transcriptional control, which implies CRY-mediated periodic rotation of transcriptionally active and inactive forms of CLOCK/BMAL1 on the promoter.

We are planning to extend this research to identify phosphorylation sites in both proteins as well as kinase(s) involved in CLOCK/BMAL1 functional regulation. We also plan to further investigate repressor function of the CLOCK/BMAL1 complex and its possible role in modulation of stress response pathways.

The second major focus of the lab is to understand the role of the circadian clock system in modulating response to cancer therapy. It has been known for years that the organism’s sensitivity to different treatments varies greatly depending on the time of application. The numerous observations led to a concept of chronotherapy, where medication is delivered in different doses at different times of the day. Such programmed administration can significantly reduce the toxicity and enhance the efficacy of cancer treatment. But it was only recently, when the identification of the major circadian genes and the discovery of the basic principles of circadian regulation of cellular physiology and metabolism provided new tools to address these phenomena at the mechanistic level. Thus, it is known now that the circadian clock regulates transcriptional output through periodic activation/repression of the set of clock-controlled genes that are involved in various metabolic pathways including those that determine in vivo response to genotoxic stress induced by different types of cancer therapies.

The key role of major circadian proteins in genotoxic stress response was first demonstrated in our laboratory by testing the sensitivity of wild type, Clock mutant, Bmal1-/- knockout and Cry1-/-Cry2-/- double-knockout animals to toxicity induced by chemotherapeutic drug cyclophosphamide. We showed that wild type mice display a robust daily rhythm in sensitivity to the drug. Importantly, the morbidity and mortality associated with treatment are at their highest levels when cyclophosphamide is administered at the times of day corresponding to minimal functional activity of the CLOCK/BMAL1 complex and the lowest at the peak times of its activity. Consistently, animals with the mutations or the targeted disruption of Clock or Bmal1 genes that are characterized with the constant low levels of CLOCK/BMAL1 transcriptional activity show high levels of drug sensitivity at all times tested. Moreover, animals with constant high levels of CLOCK/BMAL1 functional activity due to the lack of circadian repressors (Cryptochrome double-knockout animals) are extremely resistant to the treatment. These data suggest that drug sensitivity is affected by the functional status of major circadian transactivation complex, which translates into different gene expression pattern of its direct and indirect targets. Currently, we are trying to understand the underlying mechanism for circadian modulation of stress response pathways.

An important application of our discovery of the mechanism of inhibitory action of CRYs is that it provides the methodological strategy for the search for pharmacological compounds that may be used for the modulation of circadian clock function. These compounds will have a potential to be developed into pharmaceuticals used both to treat different circadian-related disorders or, in combination with conventional drugs, for rational modulation and facilitation of anticancer treatment. In order to identify such compounds we developed a cell-based readout system for monitoring the activity of CLOCK/BMAL1 transcriptional complex and performed a screening of a chemical library of 34,000 compounds for their ability to activate or repress CLOCK/BMAL1-dependent transcription. We are planning to perform detailed analysis and characterization of the isolated compounds.

Selected Publications

• Kondratov R, Chernov MV, Kondratova A, Gorbacheva V, Gudkov AV, Antoch MP. BMAL1-dependent circadian oscillation of nuclear CLOCK. Genes Dev 17:1921-1932, 2003. 
• Gorbacheva VY, Kondratov RV, Zhang R, Cherukuri S, Gudkov AV, Takahashi JS, Antoch MP. Circadian sensitivity to the chemotherapeutic agent cyclophosphamide depends on the functional status of the CLOCK/BMAL1 transactivation complex. Proc Natl Acad Sci USA 102(9):3407-3412, 2005. 
• Kondratov RV, Shamanna RK, Kondratova AA, Gorbacheva VY, Antoch MP. Dual role of the CLOCK/BMAL1 circadian complex in transcriptional regulation. FASEB J 20:530-532, 2006.
• Kondratov RV, Kondratova AA, Lee C, Gorbacheva VY, Chernov MV, Antoch MP. Post-translational regulation of circadian transcriptional CLOCK(NPAS2)/BMAL1 complex by CRYPTOCHROMES. Cell Cycle 5(8):890-895, 2006.
• Kondratov RV, Kondratova AA, Gorbacheva VY, Vykhovanets OV, Antoch MP. Early aging and age-related pathologies in mice deficient in BMAL1, the core component of the circadian clock. Genes Dev20(14):1868-1873, 2006. 
• Antoch MP, Kondratov RV, Takahashi JS. Circadian clock genes as modulators of sensitivity to genotoxic stress. Cell Cycle 4(7):901-907, 2005.
• Kondratov RV, Gorbacheva VY, Antoch MP. The role of mammalian circadian proteins in normal physiology and genotoxic stress responses. Curr Top Dev Biol 78:173-216, 2007.
• Kondratov RV, Antoch MP. Circadian proteins in the regulation of cell cycle and genotoxic stress responses. Trends Cell Biol 17(7):311-317, 2007. 

 Selected Publications (please click here for a complete PubMed list for Dr. Antoch).