-
Children with Leukaemia Scientific ConferenceWednesday 8th September 2004
Novel insights into photoreception, Novel insights into photoreception, phototransductionphototransduction and biological rhythms and biological rhythms
–– how might this impact on how might this impact on carcinogenesis?carcinogenesis?
Russell G. [email protected]
-
Successfully fighting Successfully fighting cancer is dependent cancer is dependent
upon integrating upon integrating information across a information across a range of disciplines.range of disciplines.
-
Children with Leukaemia Scientific ConferenceWednesday 8th September 2004
Novel insights into Novel insights into photoreception, photoreception, phototransductionphototransduction and biological rhythmsand biological rhythms
–– how might this impact on how might this impact on carcinogenesis?carcinogenesis?
Russell G. [email protected]
-
Known links with Known links with cancer and the cancer and the
circadian systemcircadian system -- fall fall under three interlinked under three interlinked
categoriescategories
-
Links with cancer and the circadian system fall under three interlinked categories:
(i)(i) Treatment Treatment -- ChronotherapyChronotherapy or the timed or the timed application of antiapplication of anti--cancer drugs.cancer drugs.
G. E. Rivard, C. Infante-Rivard, M. F. Dresse, J. M. Leclerc and J. Champagne. Circadian time-dependent response of
childhood lymphoblastic leukemia to chemotherapy: A long-term follow-up study of survival, Chronobiol Int, 1993, 10,
201-204.
The study found that the risk of relapse was 2.56 times higher in children who received chemotherapy in the morning than in those
receiving the same treatment in the evening.
-
Links with cancer and the circadian system fall under three interlinked categories:
(ii) Cause (ii) Cause -- Circadian regulation of the cell Circadian regulation of the cell cycle.cycle.
L. Fu and C. C. Lee, The circadian clock: Pacemaker and tumour suppressor, Nat Rev Cancer, 2003, 3, 350-361.
The links between the circadian system and cell proliferation –e.g. Per2-mutant mice more susceptible to cancer – Per2
normally inhibits c-Myc signalling pathway.
-
Links with cancer and the circadian system fall under three interlinked categories:
(iii) Cause (iii) Cause -- Circadian disruption of due to Circadian disruption of due to abnormal environmental conditions.abnormal environmental conditions.
J. C. Li and F. Xu, Influences of light-dark shifting on the immune system, tumor growth and life span of rats, mice and fruit
flies as well as on the counteraction of melatonin, Biol Signals, 1997, 6, 77-89.
Carcinoma-bearing rats showed increased tumour growth and reduced survivalwhen kept under alternating light/dark (LD) cycles of 14L:10D followed by
10L:14D every 3 days
Continued:
-
Schernhammer ES, Laden F, Speizer FE, Willett WC, Hunter DJ, Kawachi I, Fuchs CS, Colditz GA. Night-shift work and risk of
colorectal cancer in the nurses' health study. J Natl Cancer Inst. 2003 Jun 4;95(11):825-8.
Sephton S, Spiegel D Circadian disruption in cancer: a neuroendocrine-immune pathway from stress to disease? Brain
Behav Immun. 2003 Oct;17(5):321-8.
Davis S, Mirick DK, Stevens RG Night shift work, light at night, and risk of breast cancer. J Natl Cancer Inst. 2001 Oct
17;93(20):1557-62.
-
One environmental factor One environmental factor that can be linked to all that can be linked to all
three of these categories of three of these categories of cancer and the circadian cancer and the circadian
system is system is lightlight
-
Light adjusts the clock to the appropriate phase of the circadian cycle for
chronopharmacology
-
Light adjusts the clock to the appropriate phase of the circadian cycle for
chronopharmacology
Light alters the expression of certain clock genes which in-turn regulate the cell cycle
-
Light adjusts the clock to the appropriate phase of the circadian cycle for
chronopharmacology
Light alters the expression of certain clock genes which in-turn regulate the cell cycle
Light exposure is primarily responsible for the synchronisation of the circadian system,
and through abnormal exposure to light, circadian disruption
-
Is abnormal light exposure a “risk factor” for
childhood leukaemia?
-
Is abnormal light exposure a “risk factor” for
childhood leukaemia?
Better understanding of the mechanisms
whereby light regulates the circadian system
-
The Circadian System
The “time-signal” that coordinates
rhythmicity in physiology and
behaviourSCN(Suprachiasmatic nuclei)
-
The Circadian System
Eye SCN(Suprachiasmatic nuclei)
A clock is not a clock unless it is set to local time!
Light is the primary “zeitgeber” -changes in the quantity and quality of
light at dawn and dusk.
-
Eye SCN
Behaviour
Endocrine
Peripheral oscillators
ActivitySleep/wake
MelatoninCortisol
HeartLiverLung
-
Eye SCN
Behaviour
Endocrine
Peripheral oscillators
ActivitySleep/wake
MelatoninCortisol
HeartLiverLung
-
The receptor mechanisms that adjust the clock to the light/dark cycle are complex and involve non‐rod, non‐
cone photoreceptors.
-
NonNon--rod, nonrod, non--cone photoreception in the cone photoreception in the vertebrate eyevertebrate eye
•• A novel ocular photoreceptor?A novel ocular photoreceptor?
•What is the nature of the novel
photopigment?
•Which retinal neurones are photosensitive?
•What about melanopsin?
• Is melanopsin the circadian photopigment?
-
The rodless + coneless mouse (rd/rd cl)
X
rd/rd cl/‐
-
Circadian Adjustment to the Light Cycle
Responses to a single 15 min. light‐pulse are
broadly similar between +/+ and rd/rd clmice
Freedman, M. S., Lucas, R. J., Soni, B., von Schantz, M., Munoz, M., David‐Gray, Z. K. and Foster, R. G. (1999).
Regulation of mammalian circadian behavior by non‐rod, non‐cone, ocular photoreceptors. Science 284, 502‐504.
Lucas, R. J., Freedman, M. S., Munoz, M., Garcia‐Fernandez, J. M. and Foster, R. G. (1999). Regulation of the mammalian pineal by non‐rod, non‐cone, ocular photoreceptors. Science 284, 505‐507.
-
The eye contains a non-rod, non-cone photoreceptor that
regulates the circadian system – and probably a
range of other physiological responses to light.
-
Sleep - Photic modulation of VLPO activity in the rd/rd cl mouse.
15 – 60 min.
Sham Light
0 12 24X4 fold induction of Fos by
light in the VLPO
-
NonNon--rod, nonrod, non--cone photoreception in the cone photoreception in the vertebrate eyevertebrate eye
• A novel ocular photoreceptor?
••What is the nature of the novel What is the nature of the novel
photopigmentphotopigment? ?
•Which retinal neurones are photosensitive?
•What about melanopsin?
• Is melanopsin the circadian photopigment?
-
Describing the spectral sensitivity or action spectrum of any light‐dependent
response is a critical step in characterising the
photopigments upon which the response is based – you can deduce biochemistry.
-
Action Spectrum for Phase Shifting Circadian Locomotor
Rhythms in rd/rd cl mice.
Novel Opsin with a λmax ~ 480 nm
Hattar, S., Lucas, R.J., Mrosovsky, N., Thompson, S., Douglas, R.H., Hankins,
M.W., Lem, J., Biel, M., Hofmann, F., Foster, R.G. & Yau, K.W.
Melanopsin and rod-cone photoreceptive systems account for all major accessory
visual functions in mice.
Nature, 424 76-81 (2003)
-
Action Spectrum for Phase Shifting Circadian Locomotor
Rhythms in rd/rd cl mice.
Novel Opsin with a λmax ~ 480 nm
Hattar, S., Lucas, R.J., Mrosovsky, N., Thompson, S., Douglas, R.H., Hankins,
M.W., Lem, J., Biel, M., Hofmann, F., Foster, R.G. & Yau, K.W.
Melanopsin and rod-cone photoreceptive systems account for all major accessory
visual functions in mice.
Nature, 424 76-81 (2003)
-
~ 480 nm = “blue” light photopigment
-
0
0.5
1
1.5
2
2.5
log(
% s
ensi
tivity
)
350 400 450 500 550 600 650
Wavelength (nm)
Arabidopsis cry1**
Opsin Template λmax 479nm
Flavoprotein Action Spectrum*
* Phycomyces phototropism Smyth et al (1988) Progr Phycol Res6:255-286** Action spectrum for hypocotyl elongation in cry1 overexpressingArabidopsis Ahmad et al (2002) Plant Physiology 129:774-785
No direct evidence No direct evidence for a for a flavoproteinflavoproteinor or cryptochromecryptochrome‐‐
based based photopigmentphotopigment
-
0
0.5
1
1.5
2
2.5
log(
% s
ensi
tivity
)
350 400 450 500 550 600 650
Wavelength (nm)
Arabidopsis cry1**
Opsin Template λmax 479nm
Flavoprotein Action Spectrum*
* Phycomyces phototropism Smyth et al (1988) Progr Phycol Res6:255-286** Action spectrum for hypocotyl elongation in cry1 overexpressingArabidopsis Ahmad et al (2002) Plant Physiology 129:774-785
No direct evidence No direct evidence for a for a flavoproteinflavoproteinor or cryptochromecryptochrome‐‐
based based photopigmentphotopigment
Russell Van Gelder (Washington University School of Medicine) “It would thus appear that the primary photopigment in non-
visual photoreception is opsin-dependent, but not
cryptochrome-dependent” (Panda et al., 2003).
-
Are we like mice?Are we like mice?
-
rd/rd rd/rd clcl mouse pupil mouse pupil and circadian action and circadian action
spectra.spectra.
Action spectra for melatonin Action spectra for melatonin suppression and cone ERG in suppression and cone ERG in
humans. Data normalised and rehumans. Data normalised and re‐‐plotted from:plotted from:
Brainard, G.C., Brainard, G.C., HanifinHanifin, J.P., , J.P., GreesonGreeson, J.M., Byrne, B., , J.M., Byrne, B., Glickman, G., Glickman, G., GernerGerner, E., & , E., & RollagRollag, M.D. (2001). Action , M.D. (2001). Action
spectrum for melatonin regulation in humans: spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor. evidence for a novel circadian photoreceptor. J J
NeurosciNeurosci, 21, 21, 6405, 6405‐‐6412.6412.
ThapanThapan, K., Arendt, J., & Skene, D.J. (2001). An action , K., Arendt, J., & Skene, D.J. (2001). An action spectrum for melatonin suppression: evidence for a spectrum for melatonin suppression: evidence for a novel nonnovel non‐‐rod, nonrod, non‐‐cone photoreceptor system in cone photoreceptor system in
humans. humans. J J PhysiolPhysiol, 535, 535, 261, 261‐‐267.267.
Hankins, M.W., & Lucas, R.J. (2002). The primary Hankins, M.W., & Lucas, R.J. (2002). The primary visual pathway in humans is regulated according to visual pathway in humans is regulated according to longlong‐‐term light exposure through the action of a nonterm light exposure through the action of a non‐‐classical classical photopigmentphotopigment. . Current Biology, 12Current Biology, 12, 191, 191‐‐198.198.
-
rd/rd rd/rd clcl mouse pupil mouse pupil and circadian action and circadian action
spectra.spectra.
Action spectra for melatonin Action spectra for melatonin suppression and cone ERG in suppression and cone ERG in
humans. Data normalised and rehumans. Data normalised and re‐‐plotted from:plotted from:
Brainard, G.C., Brainard, G.C., HanifinHanifin, J.P., , J.P., GreesonGreeson, J.M., Byrne, B., , J.M., Byrne, B., Glickman, G., Glickman, G., GernerGerner, E., & , E., & RollagRollag, M.D. (2001). Action , M.D. (2001). Action
spectrum for melatonin regulation in humans: spectrum for melatonin regulation in humans: evidence for a novel circadian photoreceptor. evidence for a novel circadian photoreceptor. J J
NeurosciNeurosci, 21, 21, 6405, 6405‐‐6412.6412.
ThapanThapan, K., Arendt, J., & Skene, D.J. (2001). An action , K., Arendt, J., & Skene, D.J. (2001). An action spectrum for melatonin suppression: evidence for a spectrum for melatonin suppression: evidence for a novel nonnovel non‐‐rod, nonrod, non‐‐cone photoreceptor system in cone photoreceptor system in
humans. humans. J J PhysiolPhysiol, 535, 535, 261, 261‐‐267.267.
Hankins, M.W., & Lucas, R.J. (2002). The primary Hankins, M.W., & Lucas, R.J. (2002). The primary visual pathway in humans is regulated according to visual pathway in humans is regulated according to longlong‐‐term light exposure through the action of a nonterm light exposure through the action of a non‐‐classical classical photopigmentphotopigment. . Current Biology, 12Current Biology, 12, 191, 191‐‐198.198.
-
NonNon--rod, nonrod, non--cone photoreception in the cone photoreception in the vertebrate eyevertebrate eye
• A novel ocular photoreceptor?
•What is the nature of the novel
photopigment?
••Which retinal neurones are photosensitive?Which retinal neurones are photosensitive?
•What about melanopsin?
• Is melanopsin the circadian photopigment?
-
Intrinsically Photosensitive Ganglion Cells
Berson et al. (2002)
Electrophysiology
Sekaran et al. (2003)
Calcium Imagingrd/rd cl retina
0.005DF/F
100 sec
-
rd/rd cl
Rods and cones ablated
-
We observe different types of response
50 sec
0.005∆F/F
Transient
50 sec
0.004∆F/F
Sustained
50 sec
0.005∆F/F
Repetitive
-
Pharmacological Studies
control carbenoxalone0
1
2
3
% c
ells *
Population is reduced by half when gap-junction
coupling is blocked. Though the diversity of
responses is unaffected.
Plexus or network of cells Plexus or network of cells not all of which show not all of which show
direct photosensitivitydirect photosensitivity
-
The Development of Inner Retinal Photoreceptors
-
Photosensitivity from birth – before the rods and cones have developed!
time (sec) after lights on0.005DF/F
50 sec0 8 16 24
P0
0 100%
2.9 x 10154.7 x 1013 4.4 x 1014
50sec
-
NonNon--rod, nonrod, non--cone photoreception in the cone photoreception in the vertebrate eyevertebrate eye
• A novel ocular photoreceptor?
•What is the nature of the novel
photopigment?
•Which retinal neurones are photosensitive?
••What about What about melanopsinmelanopsin??
• Is melanopsin the circadian photopigment?
-
The photosensitive retinal ganglion cells The photosensitive retinal ganglion cells ((RGCsRGCs) that project to the SCN express ) that project to the SCN express
melanopsinmelanopsin! !
-
What happens to circadian responses to light if the
rods, cones, andmelanopsin are all ablated
in the same animal?
Lucas, R.J., Hattar, S., Takao, M., Berson, D.M., Foster, R.G. and Yau, K.‐W., Diminished pupillary light reflex at high irradiances in melanopsin‐knockout
mice, Science, 299 (2003) 245‐247.
-
Circadian
Hattar, S., Lucas, R.J., Mrosovsky, N., Thompson, S., Douglas, R.H., Hankins, M.W., Lem, J., Biel, M., Hofmann, F., Foster, R.G. & Yau, K.W.
Melanopsin and rod-cone photoreceptive systems account for all major accessory visual functions in mice.
Nature, 424 76-81 (2003)
-
NonNon--rod, nonrod, non--cone photoreception in the cone photoreception in the vertebrate eyevertebrate eye
• A novel ocular photoreceptor?
•What is the nature of the novel
photopigment?
•Which retinal neurones are photosensitive?
•What about melanopsin?
•• Is Is melanopsinmelanopsin the circadian the circadian photopigmentphotopigment??
-
Gene ablation studies tell you that a
gene is/is not important – but such
studies do not tell you the function of
the gene!
-
The case for melanopsin as a photopigment is not yet settled.
• Functional biochemical data is incomplete.
-
The case for melanopsin as a photopigment is not yet settled.
• Functional biochemical data is incomplete.
• The structure of melanopsin does not resemble
the known photosensory opsins.
-
The case for melanopsin as a photopigment is not yet settled.
• Functional biochemical data is incomplete.
• The structure of melanopsin does not resemble
the known photosensory opsins.
• Melanopsin is expressed outside the
photosensory ganlion cells of mice.
-
•• There is a complex network of There is a complex network of
directly lightdirectly light‐‐sensitive sensitive RGCsRGCs
that provide light information that provide light information
to the circadian system.to the circadian system.
•• Calcium is part of the light Calcium is part of the light
signalling pathway.signalling pathway.
•• MelanopsinMelanopsin is a critical is a critical
element for the photosensitive element for the photosensitive
RGCsRGCs ‐‐ But if melanopsin is a But if melanopsin is a
photosensoryphotosensory pigment it is pigment it is
like no other.like no other.
-
How can an understanding of
mechanisms of the photicinput to the circadian
system help us?
-
Need to establish whether abnormal light Need to establish whether abnormal light exposure is a “risk factor” for leukaemia and exposure is a “risk factor” for leukaemia and
other forms of cancer other forms of cancer
-
Need to establish whether abnormal light Need to establish whether abnormal light exposure is a “risk factor” for leukaemia and exposure is a “risk factor” for leukaemia and
other forms of cancer other forms of cancer
Light treatments could provide new ways to manipulate Light treatments could provide new ways to manipulate the cell cycle and cellular proliferation. Will different light the cell cycle and cellular proliferation. Will different light treatments or the pharmacological replacement of light treatments or the pharmacological replacement of light
alter tumour progression alter tumour progression in vivoin vivo??
-
Need to establish whether abnormal light Need to establish whether abnormal light exposure is a “risk factor” for leukaemia and exposure is a “risk factor” for leukaemia and
other forms of cancer other forms of cancer
Light treatments could provide new ways to manipulate the cell cycle and cellular proliferation. Will different light treatments or the pharmacological replacement of light
alter tumour progression in vivo?
Inform approaches of “light hygiene” for all age groups. Inform approaches of “light hygiene” for all age groups. What is the most appropriate light exposure to mitigate What is the most appropriate light exposure to mitigate some of the problems of abnormal light exposure in our some of the problems of abnormal light exposure in our
24/7 society?24/7 society?
-
Acknowledgements
ImperialMark HankinsRobert Lucas
James BellinghamDaniela LupiMarta MuñozStuart Peirson
Joanne ApplefordJason Butler
Melanie FreedmanParaskevi MoutsakiAlistair Philp Ma’ayan Semo
Stewart ThompsonAaron Jenkins
WorldWim DeGrip
Nicholas MrosovskyRon Douglas
Ignacio ProvencioGlen Jeffrey
David WhitmoreKing‐Wai Yau
http://www.wellcome.ac.uk/en/1/hme.html
Responses to a single 15 min. light-pulse are broadly similar between +/+ and rd/rd cl miceThe eye contains a non-rod, non-cone photoreceptor that regulates the circadian system – and probably a range of other physiolSleep - Photic modulation of VLPO activity in the rd/rd cl mouse.What happens to circadian responses to light if the rods, cones, and melanopsin are all ablated in the same animal?Acknowledgements