Novel insights into photoreception, phototransduction and ...cwl2004.powerwatch.org.uk/programme/speakers/day3-foster-pres.pdf · childhood lymphoblastic leukemia to chemotherapy:

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.


(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.


(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


chronopharmacology

Light alters the expression of certain clock genes which in-turn regulate the cell cycle


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

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


• A novel ocular photoreceptor?

••What is the nature of the novel What is the nature of the novel

photopigmentphotopigment? ?




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)

~ 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.




photopigment?

••Which retinal neurones are photosensitive?Which retinal neurones are photosensitive?



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




photopigment?


••What about What about melanopsinmelanopsin??


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)




photopigment?



•• 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 structure of melanopsin does not resemble

the known photosensory opsins.



• 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



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??



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

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Novel insights into photoreception, phototransduction and ...cwl2004.powerwatch.org.uk/programme/speakers/day3-foster-pres.pdf · childhood lymphoblastic leukemia to chemotherapy: