1984-1990 Studium der Biologie: Universität Köln
1990-1994 Promotion: Universität Köln
1994-1998 Postdoctoral research associate: Brandeis University, Waltham, USA
1998-2006 Forschungsgruppenleiter am Institut für Zoologie, Universität Regensburg
2006-2013 Professor of Neurobiology, School of Biological and Chemical Sciences, Queen Mary, Universtiy of London, UK
2013-2016 Professor of Neurogenetics and Biological Timing, Department of Cell and Developmental Biology, University College London, UK
-neuronale und molekulare Mechanismen der Synchronisation zirkadianer Uhren
-Identifizierung zirkadianer Photo- und Thermorezeptoren
-Mechanismen der Temperaturkompensation zirkadianer Uhren
Life on our planet evolved in the context of the daily light/dark changes caused by the earths’ rotation around its own axis. As a consequence most organisms developed ‘circadian clocks’, which enable them to anticipate environmental changes in order to adapt their physiology and behaviour accordingly.
On a genetic and molecular level, these circadian clocks are constituted by dedicated clock genes and the proteins they encode. In higher organisms, these genes are expressed in neuronal pacemaker centres in (or close to) the brain, which coordinate the temporal organisation of many biological processes, like for example sleep/wake rhythms in humans.
The genetic make-up of these circadian clocks is remarkably similar between mammals and insects, which is exemplified by the period gene—a central clock gene both in humans and in fruit flies.
Research in our lab focuses on the genetic and neuronal substrates that contribute to the regulation of the rest/activity cycles in the fruit fly Drosophila melanogaster. In 1971 the first clock gene in any higher eukaryote was identified in this organism by Ron Konopka in Seymour Benzer’s laboratory. Since then, circadian clock research accelerated in many labs around the world and today we have a rather detailed understanding of the underlying molecular mechanisms in both Drosophila and mammals (Stanewsky et al., 2003). Nevertheless, several fundamental questions about circadian timekeeping remain unanswered, and with our work we attempt to answer at least some of them.
How can light/dark cycles reset circadian clocks?
Circadian clocks are self-sustained molecular oscillators and keep ticking in the absence of any environmental cues. But in order to be a useful tool for advantageous timing of biological processes in a natural day/night setting, these environmental changes must be able to influence (or reset) the molecular oscillations. In flies, an important photoreceptor mediating this ‘light-synchronization’ is the blue-light photoreceptor Cryptochrome (Cry) (Stanewsky et al., 1998). Interestingly, Cry is expressed within the brain clock neurons that drive the rest/activity cycles of the fly—so it’s a photoreceptor expressed in the brain. But it is clear that the visual photoreceptors in the retina of the fly are also important for light-synchronization, as well as sub-retinal structure known as the Hofbauer-Buchner eyelet (Yoshii et al., 2009, Helfrich-Förster et al., 2001, Stanewsky et al., 1998, Veleri et al., 2007, Emery et al., 2000). Current research in our lab tries to determine why such a complexity of photoreceptors and light-inputs is needed and used for proper clock resetting, and which role the non-visual Hofbauer-Buchner eyelet may play.
How does light synchronize the molecular clock works?
Most clock genes are expressed in a rhythmic fashion, meaning that like the biological processes they control, their expression reaches peak and trough values once during a 24-hr day (Stanewsky et al., 2003). In order to adjust these molecular oscillations to changing environmental conditions (for example the seasonal changes of day length), clock gene expression must somehow respond to changes in illumination. In flies, the clock protein Timeless (Tim) is degraded upon light-exposure. Since Tim is required to stabilize the clock protein Period (Per), the whole molecular oscillations are reset according to the light-dependent degradation of Tim. Therefore, light-signalling to Tim is a crucial step in light-resetting. Cry is probably the major photoreceptor mediating this task. Upon illumination Cry is thought to undergo a conformational change allowing it to bind to Tim. As a consequence both Tim and Cry become a substrate for the F-box protein Jetlag (Jet) and are subsequently degraded by the proteasome (Peschel et al., 2006, 2009). Although the light-dependent Cry/Tim/Jet interactions are arguably a crucial part of the molecular light-resetting apparatus, it is clear that Tim degradation can also be achieved by a Cry-independent pathway, because some clock neurons are ‘immune’ to a lack of Cry function (Stanewsky et al., 1998; Helfrich-Förster et al., 2001; Veleri et al., 2007). Current projects in our lab aim to identify both, novel factors mediating this alternative resetting pathway, and additional ones contributing to the Cry/Tim/Jet pathway.
Daily temperature fluctuations also synchronize circadian clocks
In nature, both the daily changes of light and dark and the concomitant changes in ambient temperature serve as signals to synchronize circadian clocks. In order to understand how these two pathways are integrated on a neuronal and molecular level we initiated studies using only temperature cycles as synchronizing factor (Glaser & Stanewsky, 2005). We found that both behavioural and molecular rhythms in Drosophila can be synchronized by temperature cycles within the physiological range of the fly (16°C to 29°C). Moreover, we were able to isolate several mutations that specifically interfere with synchronization to temperature cycles and not to light/dark cycles, demonstrating that the two input-pathways are distinct (Glaser & Stanewsky, 2005). The nocte mutant (for no circadian temperature entrainment) maps to a gene encoding a novel protein of unknown function. Further analysis indicates that nocte function within certain peripheral sensory structures is required for synchronization of the clock neurons within the brain and the behavioural rhythms controlled by these neurons (Sehadova et al., 2009). In contrast to light signals, which can be received by the clock neurons directly (via Cry, see above), temperature input to the brain therefore seems to require a novel periphery-to-brain neuronal pathway. Using Nocte protein-protein interaction screens, we identified the variant glutamate receptor IR25a as a new component of this peripheral thermosensing pathway (Chen et al 2015). Current research in our lab is aimed to further characterise this pathway by identifying other factors involved using a combination of candidate approaches, and characterization of newly isolated temperature synchronization mutants.
Temperature compensation: the holy grail of circadian clocks?
Even though daily temperature fluctuations serve as a synchronizing signal for circadian clocks (see above), clocks are also temperature compensated. This means that when kept under constant conditions (i.e., no daily fluctuations of either light/dark or temperature), circadian clocks tick at the same speed at low or high constant temperatures. This is quite a remarkable feature, because (a) temperature cycles do influence the clock (see above), and (b) biochemical reactions usually occur at a faster rate at higher temperatures. Temperature compensation is even more remarkable when considering poikilotherm animals like Drosophila, who adjust their body temperature with that of the environment. Of course it is crucial that circadian clocks are temperature compensated, because a clock that runs with different speed at different temperatures would not be a clock (rather a thermometer). Despite this fascinating feature, the molecular mechanisms underlying temperature compensation are not understood in any system. In Drosophila several models have been put forward that implicate temperature-dependent inter- and intra-molecular interactions between key clock proteins as crucial part of this mechanism. Recently, we identified a region within the Period protein that disrupts temperature compensation when altered. Similarly, we could show that a different region of this clock protein is important for the formation of a Per:Per homodimer and reveal its function within the circadian clock mechanism (Landskron et al., 2009). Following similar approaches, we are now determining the potential effects on protein:protein interactions mediated by the temperature compensation defective Per protein we identified. Our preliminary data lead to a hypothesis whereby temperature-dependent protein interactions between different clock proteins (e.g., Per and Tim) influence the rates of nuclear import and export of these proteins. Because the nuclear concentrations of Per and Tim influence the transcription rate of their own RNA, temperature-controlled nuclear-cytoplasmic shuttling could represent a basic principle of temperature compensation, at least in Drosophila.
Please contact us for further information regarding current projects in our group.
1) R. Klemz, S. Reischl, T. Wallach, N. Witte, K. Jürchott, S. Klemz, V. Lang, S. Lorenzen, M. Knauer, S. Heidenreich, M.Xu, J.A. Ripperger, M.Schupp, R.Stanewsky, A. Kramer (2016). Reciprocal regulation of carbon monoxide metabolism and the circdaian clock. Nat Struct Mol Biol (Nov 28, Epub ahead of print)
2) R.E.F. Harper, P. Dayan, J.T. Albert, R. Stanewsky (2016). Sensory conflict disrupts activity of the Drosophila circadian network. Cell Rep 17:1711-1718
3) E. Buhl, A. Bradlaugh, M. Ogueta, K-F. Chen, R. Stanewsky, J.J.L. Hodge (2016). Quasimodo mediates daily and acute light effects on Drosophila clock neuron excitability. Proc Natl Acad Sci USA 113:13486-13491.
4) C. Chen, E. Buhl, M. Xu, V. Croset, J.S. Rees, K.S. Lilley, R. Benton, J.J. Hodge, R. Stanewsky (2015). Drosophila Ionotropic Receptor 25a mediates circadian clock resetting by temperature. Nature 527:516-520.
5) S. Roessingh, W. Wolfgang, R. Stanewsky (2015). Loss of Drosophila melanogaster TRPA1 function affects ‘siesta’ behavior but not synchronization to temperature cycles. J Biol Rhythms 30:492-505.
6) A. Simoni, W. Wolfgang, MP Topping, RG Kavlie, R. Stanewsky, and J. Albert (2014). A mechanosensory pathway to the Drosophila circadian clock. Science 343:525-528.
7) W. Wolfgang, A. Simoni, C. Gentile, and R. Stanewsky (2013). The Pyrexia transient receptor potential channel mediates circadian clock synchronization to low temperature cycles in Drosophila melanogaster. Proc Biol Sci 280: 20130959.
8) C. Gentile, H. Sehadova, A. Simoni, C. Chen, and R.Stanewsky (2013). Cryptochrome antagonizes synchronization of Drosophila’s circadian clock to temperature cycles Current Biology 23: 185-195.
9) L. Chittka, R.J. Stelzer, and R. Stanewsky (2013). Daily changes in UV light levels can synchronize the circadian clock of bumblebees (Bombus terrestris). Chronobiol Int 30:434-442.
10) J. Szular, H. Sehadova, C. Gentile, G. Szabo, W.-H. Chou, S.G. Britt, and R. Stanewsky (2011). Rhodopsin 5 and Rhodopsin 6 mediated clock synchronization in Drosophila melanogaster is independent of retinal Phospholipase C-ß signalling. J Biol Rhythms 27: 25-36.
11) F. Chen, N. Peschel, R. Zavodska, H. Sehadova, and R. Stanewsky (2011). QUASIMODO, a novel light-responsive protein involved in light-input to the Drosophila circadian clock. Current Biology 21: 719-729.
12) J. Stelzer, R. Stanewsky, and L. Chittka (2010). Circadian foraging rhythms of bumblebees monitored by radio-frequency identification. J Biol Rhythms 25: 257-267.
13) Sehadova, F.T. Glaser, C. Gentile, A. Simoni, A. Giesecke, J.T. Albert, and R. Stanewsky (2009). Temperature entrainment of Drosophila's circadian clock involves the novel gene nocte and signaling from peripheral tissues to the brain. Neuron 64: 251-266.
14) J. Landskron, K-F. Chen, E. Wolf, and R. Stanewsky (2009). A role for the PERIOD:PERIOD homodimer in the Drosophila circadian clock. PLoS Biol 7(4):e3.
15) TT. Yoshii, C. Wülbeck, H. Sehadova, S. Veleri, D. Bichler, R. Stanewsky, and C. Helfrich-Förster (2009). The neuropeptide pigment-dispersing factor adjusts period and phase of Drosophila's clock. J. Neurosci 29: 2597-6.
16) N. Peschel, K-F. Chen, G. Szabo, and R. Stanewsky (2009). Light-dependent interactions between the Drosophila circadian clock factors Cryptochrome, Jetlag, and Timeless. Current Biology 19: 241-247.
17) J.J. Hodge and R. Stanewsky (2008). Function of the Shaw potassium channel within the Drosophila circadian clock. PLoS ONE 3(5): e2274
18) T. Yoshii, T. Todo, C. Wülbeck, R. Stanewsky, and C. Helfrich-Förster (2008) Cryptochrome is present in the compound eyes and a subset of Drosophila's clock neurons. J Comp Neurol 20: 952-66.
19) F. Sandrelli, E. Tauber, M. Pegoraro, G. Mazzotta, P. Cisotto, J. Landskron, R. Stanewsky, A. Piccin, E. Rosato, M. Zordan, R. Costa, and C.P. Kyriacou (2007). A molecular basis for natural selection at the timeless locus in Drosophila melanogaster Science 316: 1898-1900.
20) S. Veleri, D. Rieger, C. Helfrich-Förster, and R. Stanewsky (2007). Hofbauer-Buchner eyelet affects circadian photosensitivity and coordinates TIM and PER expression in Drosophila clock neurons. J Biol Rhythms 22: 29-42.
21) N. Peschel, S. Veleri, and R. Stanewsky (2006). Veela defines a molecular link between Cryptochrome and Timeless in the light-input pathway to Drosophila's circadian clock. Proc Natl Acad Sci USA 103:17313-17318.
22) B. Collins, E.O. Mazzoni, R. Stanewsky, and J. Blau (2006). Drosophila Cryptochrome is a circadian transcriptional repressor. Current Biology 16: 441-449.
23) F.T. Glaser and R. Stanewsky (2005). Temperature synchronization of the Drosophila circadian clock. Current Biology 15: 1352-1363.
24) C. Wülbeck, G. Szabo, O.T. Shafer, C. Helfrich-Förster, and R. Stanewsky (2004). The novel Drosophila timblind mutant affects behavioral rhythms but not periodic eclosion. Genetics 169: 751-766.
25) S. Veleri, C. Brandes, C. Helfrich-Förster, J.C. Hall, and R. Stanewsky (2003). A self-sustaining, light-entrainable neuronal circadian oscillator in the brain of Drosophila Current Biology 13:1758-1767.
26) D. Rieger, R. Stanewsky, and C. Helfrich-Förster (2003). Cryptochrome, compound eyes, Hofbauer-Buchner eyelets, and ocelli play different roles in the entrainment and masking pathway of the locomotor activity rhythm in the fruit fly Drosophila melanogaster. J Biol Rhythms 18:377-391.
27) C. Helfrich-Förster, T. Edwards, K. Yasuyama, B. Wisotzki, S. Schneuwly, R. Stanewsky, I.A. Meinertzhagen, and A. Hofbauer (2002) The extraretinal eyelet of Drosophila: development, ultrastructure, and putative circadian function. J Neurosci 22:9255-9266.
28) R. Stanewsky, K. Sison, C. Brandes, and J.C. Hall (2002). Mapping of elements involved in regulating normal temporal period and timeless RNA expression patterns in Drosophila melanogaster. J Biol Rhythms 17:293-306.
29) T. Stempfl, M. Vogel, G. Szabo, C. Wülbeck, J. Liu, J.C. Hall, and R. Stanewsky (2002). Identification of circadian-clock regulated enhancers and genes of Drosophila melanogaster by transposon mobilization and luciferase reporting of cyclical gene expression. Genetics 160:571-593.
30) L.M. Beaver, B.O. Gvakharia, T.S. Vollintine, D.M. Hege, R. Stanewsky, and J.M. Giebultowicz (2002). Loss of circadian clock function decreases reproductive fitness in males of Drosophila melanogaster. Proc Natl Acad Sci USA 99:2134-2139.
31) C. Helfrich-Förster, C. Winter, A. Hofbauer, J.C. Hall, and R. Stanewsky (2001). The circadian clock of Drosophila is blind after elimination of all known photoreceptors. Neuron 30: 1-20.
32) M. Ivanchenko, R. Stanewsky, and J.M. Giebultowicz (2001). Circadian photoreception in Drosophila: Functions of cryptochrome in peripheral and central clocks. J Biol Rhythms 16: 205-215.
33) P. Emery, R. Stanewsky, C. Helfrich-Förster, M. Emery-Le, J.C. Hall and M. Rosbash (2000). Drosophila CRY is a deep brain circadian photoreceptor. Neuron 26: 493-504.
34) P. Emery, R. Stanewsky, J.C. Hall and M. Rosbash (2000). A unique circadian rhythm photoreceptor. Nature 404: 456-457.
35) J.M. Giebultowicz, R. Stanewsky, J.C. Hall and D.M. Hege (2000). Transplanted Drosophila excretory tubules maintain circadian clock cycling out of phase with the host. Curr Biol 10: 107-110.
36) I. Reim, R. Stanewsky and H. Saumweber (1999). The puff-specific RRM protein NonA is a single-stranded nucleic acid binding protein. Chromosoma 108: 162-172.
37) R. Stanewsky, M. Kaneko, P. Emery, B. Beretta, K. Wager-Smith, S.A. Kay, M. Rosbash and J.C. Hall (1998). The cryb mutation identifies cryptochrome as a circadian photoreceptor in Drosophila. Cell 95: 681-692.
38) D.M. Hege, R. Stanewsky, J.C. Hall and J.M. Giebultowicz (1997). Rhythmic expression of a PER-reporter in the Malpighian Tubules of decapitated Drosophila: evidence for a brain-independent circadian clock. J Biol Rhythms 12: 300-308.
39) R. Stanewsky, C. Jamison, J.D. Plautz, S.A. Kay and J.C. Hall (1997). Multiple circadian-regulated elements contribute to cycling period gene expression in Drosophila. EMBO J 16: 5006-5018.
40) J.D. Plautz, M. Straume, R. Stanewsky, C.F. Jamison, C. Brandes, H.B. Dowse, J.C. Hall, and S.A. Kay (1997) Quantitative analysis of Drosophila period gene transcription in living animals. J Biol Rhythms 12: 204-217.
41) M.E. Dembinska, R. Stanewsky, J.C. Hall, and M. Rosbash (1997). Circadian cycling of a period-lacZ fusion protein in Drosophila: evidence for cyclical degradation. J Biol Rhythms 12: 157-172.
42) R. Stanewsky, B. Frisch, C. Brandes, M.J. Hamblen-Coyle, M. Rosbash, and J.C. Hall (1997). Temporal and spatial expression patterns of transgenes containing increasing amounts of the Drosophila clock gene period and a lacZ reporter: mapping elements of the PER protein involved in circadian cycling. J Neurosci 17: 676-696.
43) C. Brandes, J.D. Plautz, R. Stanewsky, C.F. Jamison, M. Straume, K.V. Wood, S.A. Kay, and J.C. Hall (1996). Novel features of Drosophila period transcription revealed by real-time Luciferase reporting. Neuron 16: 687-692.
44) R. Stanewsky, T.A. Fry, I. Reim, H. Saumweber, and J.C. Hall (1996). Bioassaying putative RNA-binding motifs in a protein encoded by a gene that influences courtship and visually mediated behavior in Drosophila: in vitro mutagenesis of nonA. Genetics 143: 259-275.
45) R. Stanewsky, K.G. Rendahl, M. Dill, and H. Saumweber (1993). Genetic and molecular Analysis of the X chromosomal region 14B17-14C4 in Drosophila melanogaster: loss of function in NONA, a nuclear protein common to many cell types, results in specific physiological and behavioral defects. Genetics 135: 419-442.
46) H.v. Besser, P. Schnabel, C. Wieland, E. Fritz, R. Stanewsky, and H. Saumweber (1990). The puff-specific Drosophila Protein Bj6, encoded by the gene no-on-transient A, shows homology to RNA-binding proteins. Chromosoma 100: 37-47.
47) R. Costa and R.Stanewsky (2013). When population and evolutionary genetics met behaviour. Mem Inst Oswaldo Cruz 108:74-79.
48) C.W. Mullineux and R. Stanewsky (2009). The Rolex and the hour-glass: a simplified circadian clock in Prochlorococcus? J Bacteriol 191: 5333-5335.
49) F.T. Glaser and R. Stanewsky (2008). Synchronization of the Drosophila circadian clock by temperature cycles. Cold Spring Harb Symp Quant Biol 72:233-42.
50) R. Stanewsky (2007) Analysis of rhythmic gene expression in adult Drosophila using the firefly luciferase reporter gene. Methods Mol Biol 362: 131-42.
51) R. Stanewsky (2003) Genetic analysis of the circadian system in Drosophila melanogaster and mammals. J Neurobiol 54:111-147.
52) R. Stanewsky (2002) Clock mechanisms in Drosophila. Cell Tissue Res 309:11-26.