Gurushivam at 17:21, 18 February 2026

2026-02-18T17:21:02Z

New page

{{short description|Indian biologist}}
{{Use dmy dates|date=August 2025}}
{{Use Indian English|date=August 2025}}
{{Infobox scientist
| honorific_prefix =
| name = Amita Sehgal
| honorific_suffix =
| native_name =
| native_name_lang =
| image = 
| image_size =
| image_upright =
| alt =
| caption =
| death_date = 
| death_place =
| death_cause =
| resting_place =
| resting_place_coordinates = 
| other_names =
| pronounce =
| residence =
| citizenship =
| nationality =
| fields = [[chronobiology]]
| workplaces = [[Perelman School of Medicine]]
| patrons =
| education =
| alma_mater = {{Nowrap|[[Delhi University]] <br /> [[Jawaharlal Nehru University, Delhi|Jawaharlal Nehru University]] <br /> [[Cornell University]]}}
| thesis_title = 
| thesis_url = 
| thesis_year = 
| doctoral_advisor = 
| academic_advisors = [[Michael W. Young|Michael Young]], [[Moses Chao]]
| doctoral_students =
| notable_students =
| known_for =
| influences =
| influenced =
| awards =
| author_abbrev_bot =
| author_abbrev_zoo =
| spouse = 
| partner = 
| children =
| signature = 
| signature_alt =
| website = 
| footnotes =
}}

'''Amita Sehgal''' is a [[molecular biologist]] and [[chronobiologist]] in the Department of Neuroscience at the [[Perelman School of Medicine]] at the [[University of Pennsylvania]].<ref name=":2">{{Cite web|url=https://www.med.upenn.edu/sehgallab/|title=Home | Sehgal Lab | Perelman School of Medicine at the University of Pennsylvania|website=www.med.upenn.edu}}</ref> Sehgal was involved in the discovery of ''Drosophila'' TIM and many other important components of the ''Drosophila'' clock mechanism.<ref name=":3">Pennsylvania scientist played role in research that won 2017 Nobel Prize https://www.pennlive.com/news/2017/10/pennsylvania_scientist_contrib.html</ref> Sehgal also played a pivotal role in the development of ''Drosophila'' as a model for the study of sleep.<ref name=":7">{{cite journal |last1=Sehgal |first1=Amita |last2=Mignot |first2=Emmanuel |title=Genetics of Sleep and Sleep Disorders |journal=Cell |date=July 2011 |volume=146 |issue=2 |pages=194–207 |doi=10.1016/j.cell.2011.07.004 |pmid=21784243 |pmc=3153991 }}</ref><ref>{{Cite web|url=https://www.consultant360.com/podcast/neurology/sleep-medicine/amita-sehgal-phd-using-fruit-flies-sleep-research|title = Amita Sehgal, PHD, on Using Fruit Flies for Sleep Research|date = 11 July 2019}}</ref> Her research continues to be focused on understanding the genetic basis of sleep and also how circadian systems relate to other aspects of physiology.<ref>{{Cite web|url=https://www.sleepreviewmag.com/sleep-treatments/therapy-devices/light-therapy/time-flies-amita-seghal/|title=How Time Flies: Amita Sehgal, PhD | Sleep Review|first=Sree|last=Roy|date=4 September 2016}}</ref>

== Education and early career ==
Sehgal grew up in India, and earned her BSc as an undergraduate at [[Delhi University]] and her MSc at [[Jawaharlal Nehru University, Delhi|Jawaharlal Nehru University]], both in New Delhi, India.<ref name=":0">{{Cite web|url=https://www.the-scientist.com/profile/time-flies-32620|title=Time, Flies|website=The Scientist Magazine®}}</ref> She began pursuing her PhD in cell biology and genetics at [[Cornell University]] in 1983.<ref name=":0" /> It was here, while studying a human neuronal growth factor, that her interest in science truly developed.<ref name=":0" /> In 1988, she began her Postdoctoral Fellowship at [[Rockefeller University]] in the lab of [[Michael W. Young|Michael Young]], where she had her first exposure to the study of [[circadian rhythm]]s, a field in which she has since remained.<ref name=":0" />

== Research ==

=== Timeline of selected major research contributions ===
*1994: Discovered the ''timeless'' mutation in fruit flies.
*1995: Cloned the ''timeless'' gene and showed the expression of the ''timeless'' gene has daily cycles.
*1996: Showed pulses of light degrade ''timeless''.
*2000: Developed a ''[[Drosophila]]'' model for sleep.
*2001: Showed ''neurofibromin 1'' plays a role in the circadian pathway in fruit flies.
*2006: Discovered the ''jetlag ''mutation and'' ''showed the JETLAG protein is involved in the degradation of the TIMELESS protein.
*2006: Showed mushroom bodies in fruit flies are important for sleep.
*2008: Discovered the ''sleepless'' gene in fruit flies.
*2014: Mapped neural circuits that link the clock to behavior
*2014: Discovered a function of sleep in early life
*2018: Identified a potential role of sleep in adult flies
*2018: Demonstrated circadian regulation of the blood brain barrier
*2019: Discovered a molecular link between sleep and the immune system

=== Timeless and Period ===
Amita Sehgal has contributed tremendously towards the understanding of the biological clock of ''Drosophila melanogaster''. In 1994, Sehgal, Price, Man, and Young, through [[forward genetics]], discovered a mutant of the gene [[Timeless (gene)|''timeless'']] (TIM) in ''Drosophila melanogaster''.<ref name=":3" /><ref>{{cite journal |last1=Sehgal |first1=A. |last2=Price |first2=J. L. |last3=Man |first3=B. |last4=Young |first4=M. W. |title=Loss of circadian behavioral rhythms and per RNA oscillations in the Drosophila mutant timeless |journal=Science |date=18 March 1994 |volume=263 |issue=5153 |pages=1603–1606 |doi=10.1126/science.8128246 |pmid=8128246 |bibcode=1994Sci...263.1603S }}</ref>'' ''In the following year, Sehgal and colleagues cloned TIM through [[positional cloning]] and were able to show that TIM and [[Period gene|PER]] had similar cycling levels of their mRNA.<ref name=":3" /><ref>{{cite journal |last1=Myers |first1=Michael P. |last2=Wager-Smith |first2=Karen |last3=Wesley |first3=Cedric S. |last4=Young |first4=Michael W. |last5=Sehgal |first5=Amita |title=Positional Cloning and Sequence Analysis of the Drosophila Clock Gene, timeless |journal=Science |date=3 November 1995 |volume=270 |issue=5237 |pages=805–808 |doi=10.1126/science.270.5237.805 |pmid=7481771 |bibcode=1995Sci...270..805M |s2cid=3211623 }}</ref><ref>{{cite journal |last1=Sehgal |first1=Amita |last2=Rothenfluh-Hilfiker |first2=Adrian |last3=Hunter-Ensor |first3=Melissa |last4=Chen |first4=Yifeng |last5=Myers |first5=Michael P. |last6=Young |first6=Michael W. |title=Rhythmic Expression of timeless: A Basis for Promoting Circadian Cycles in period Gene Autoregulation |journal=Science |date=3 November 1995 |volume=270 |issue=5237 |pages=808–810 |doi=10.1126/science.270.5237.808 |pmid=7481772 |bibcode=1995Sci...270..808S |s2cid=38151127 }}</ref> The model they proposed, which was confirmed over time, was that PER and TIM interact and accumulate during the day. In the evening, they enter the nucleus to inhibit the transcription of their mRNA. In 1996, Sehgal's laboratory showed that degradation in TIM levels caused by a pulse of light resets the circadian clock.<ref>{{cite journal |last1=Hunter-Ensor |first1=Melissa |last2=Ousley |first2=Andrea |last3=Sehgal |first3=Amita |title=Regulation of the Drosophila Protein Timeless Suggests a Mechanism for Resetting the Circadian Clock by Light |journal=Cell |date=March 1996 |volume=84 |issue=5 |pages=677–685 |doi=10.1016/S0092-8674(00)81046-6 |pmid=8625406 |s2cid=15049039 |doi-access=free }}</ref> Later, they showed that specific phosphatases control stability of PER and TIM in daily cycles.<ref>{{cite journal |last1=Sathyanarayanan |first1=Sriram |last2=Zheng |first2=Xiangzhong |last3=Xiao |first3=Rui |last4=Sehgal |first4=Amita |title=Posttranslational Regulation of Drosophila PERIOD Protein by Protein Phosphatase 2A |journal=Cell |date=February 2004 |volume=116 |issue=4 |pages=603–615 |doi=10.1016/S0092-8674(04)00128-X |pmid=14980226 |s2cid=295780 |doi-access=free }}</ref>

=== Neurofibromin 1 ===
[[Neurofibromin 1]] (NF1) is a [[tumor suppressor gene]] known to be dis-regulated in [[Neurofibromatosis Type 1|Neurofibromatosis type 1]], a disorder which causes tumors along the spine. In 2001, Sehgal and her colleagues learned that some patients with Neurofibromatosis type 1 also experience irregularities in their sleep, and so decided to investigate the circadian rhythms of flies with a nonfunctional NF1 gene.<ref name="Williams et al 2001">{{cite journal |last1=Williams |first1=Julie A. |last2=Su |first2=Henry S. |last3=Bernards |first3=Andre |last4=Field |first4=Jeffrey |last5=Sehgal |first5=Amita |title=A Circadian Output in Drosophila Mediated by Neurofibromatosis-1 and Ras/MAPK |journal=Science |date=21 September 2001 |volume=293 |issue=5538 |pages=2251–2256 |doi=10.1126/science.1063097 |pmid=11567138 |bibcode=2001Sci...293.2251W |s2cid=23175890 }}</ref> They found that these flies also have disrupted circadian rhythms, and these rhythms could be restored by inserting NF1 [[transgene]]s, thus proving that NF1 is involved in the circadian pathway. They showed that in flies, NF1 functions through the [[Mitogen-activated protein kinase|MAP kinase]] pathway, which is the same pathway implicated in Neurofibromatosis type 1 in humans.<ref name="Williams et al 2001"/>

=== Jetlag ===
In 2006, Sehgal and her colleagues discovered a mutant fly which takes an abnormally long time to adjust to new light-dark cycles.<ref>{{cite journal |last1=Koh |first1=Kyunghee |last2=Zheng |first2=Xiangzhong |last3=Sehgal |first3=Amita |title=JETLAG Resets the Drosophila Circadian Clock by Promoting Light-Induced Degradation of TIMELESS |journal=Science |date=23 June 2006 |volume=312 |issue=5781 |pages=1809–1812 |doi=10.1126/science.1124951 |pmid=16794082 |pmc=2767177 |bibcode=2006Sci...312.1809K }}</ref> They named the underlying mutated gene ''jetlag'' (jet). This gene codes for an [[F-box protein]] called JET, a [[ubiquitin ligase]] that facilitates resetting the drosophila clock. Sequencing of the gene revealed two [[allele]]s of ''jetlag:'' the "c" allele (common) and the "r" allele (rare). In the presence of [[Cryptochrome|CRYPTOCHROME]] (CRY), JET plays a major role in the degradation of [[Timeless (gene)|TIMELESS (TIM)]] protein in response to light, which is necessary for the clock to entrain to external light cues.

=== Mushroom bodies ===
[[Mushroom bodies]] are located in the brains of ''Drosophila'' and are known to play a role in learning, memory, olfaction, and locomotion.<ref>{{cite journal |last1=Heisenberg |first1=Martin |title=Mushroom body memoir: from maps to models |journal=Nature Reviews Neuroscience |date=April 2003 |volume=4 |issue=4 |pages=266–275 |doi=10.1038/nrn1074 |pmid=12671643 |s2cid=5038386 }}</ref> In 2006, Sehgal and her colleagues discovered that mushroom bodies also play a major role in regulating sleep in flies. By using a steroid called [[Mifepristone|RU-486 (Mifepristone)]] to regulate protein kinase A ([[Protein kinase A|PKA]]), they were able to upregulate and downregulate the expression of genes in specific areas like the mushroom bodies, and found that this structure is critical for fly sleep.<ref>{{cite journal |last1=Joiner |first1=William J. |last2=Crocker |first2=Amanda |last3=White |first3=Benjamin H. |last4=Sehgal |first4=Amita |title=Sleep in Drosophila is regulated by adult mushroom bodies |journal=Nature |date=June 2006 |volume=441 |issue=7094 |pages=757–760 |doi=10.1038/nature04811 |pmid=16760980 |bibcode=2006Natur.441..757J |s2cid=4323353 }}</ref> While the specific pathway through which these mushroom bodies regulate sleep is currently unknown, it may be that they are involved in inhibiting processing of sensory information, allowing flies to fall asleep.{{fact|date=August 2025}}

=== Sleepless ===
In 2008, Sehgal ''et al.'' discovered the ''sleepless ''gene in fruit flies through [[insertional mutagenesis]].<ref>{{cite journal |last1=Koh |first1=Kyunghee |last2=Joiner |first2=William J. |last3=Wu |first3=Mark N. |last4=Yue |first4=Zhifeng |last5=Smith |first5=Corinne J. |last6=Sehgal |first6=Amita |title=Identification of SLEEPLESS, a Sleep-Promoting Factor |journal=Science |date=18 July 2008 |volume=321 |issue=5887 |pages=372–376 |doi=10.1126/science.1155942 |pmid=18635795 |pmc=2771549 |bibcode=2008Sci...321..372K }}</ref> Mutations in the ''sleepless'' gene caused the flies to sleep 80% less than normal flies, and live half as long as normal flies. Sehgal ''et al.'' discovered that the SLEEPLESS protein regulates the voltage-gated potassium channel, Shaker, and also nicotinic acetylcholine receptors, specifically one called redeye that they discovered through another genetic screen.<ref name=":6">{{Cite web|title = HHMI Bulletin Spring 2014: Around the Clock |publisher=Howard Hughes Medical Institute |url=http://www.hhmi.org/bulletin/spring-2014/around-clock |access-date = 2015-04-09}}</ref> Sehgal ''et al.'' also found increased stem cell activity within the testes of male flies with mutations in ''sleepless''.{{fact|date=August 2025}}

=== Functions of sleep ===
All species, including humans, sleep a lot in early life. Sehgal et al discovered what keeps sleep at high levels in young fruit flies. They also found that when sleep is disrupted in early life, mating behavior is perturbed in adults.<ref>{{cite journal |last1=Kayser |first1=Matthew S. |last2=Yue |first2=Zhifeng |last3=Sehgal |first3=Amita |title=A Critical Period of Sleep for Development of Courtship Circuitry and Behavior in Drosophila |journal=Science |date=18 April 2014 |volume=344 |issue=6181 |pages=269–274 |doi=10.1126/science.1250553 |pmid=24744368 |pmc=4479292 |bibcode=2014Sci...344..269K }}</ref> Thus, sleep may be required to allow brain development for behaviors that promote survival and species propagation. In adult animals, a possible function of sleep is to promote clearance of waste.<ref>{{cite news |last1=Makin |first1=Simon |title=Deep Sleep Gives Your Brain a Deep Clean |url=https://www.scientificamerican.com/article/deep-sleep-gives-your-brain-a-deep-clean1/ |work=Scientific American |date=1 November 2019 }}</ref> Sehgal et al found that sleep promotes endocytosis through the blood brain barrier in flies.<ref>{{cite journal |last1=Artiushin |first1=Gregory |last2=Zhang |first2=Shirley L |last3=Tricoire |first3=Hervé |last4=Sehgal |first4=Amita |title=Endocytosis at the Drosophila blood–brain barrier as a function for sleep |journal=eLife |date=26 November 2018 |volume=7 |article-number=e43326 |doi=10.7554/eLife.43326 |pmid=30475209 |pmc=6255390 |doi-access=free }}</ref>

=== Clocks and behavior and the blood brain barrier ===
The blood brain barrier (BBB) protects the brain from potentially harmful molecules in the periphery, but it can also impede the delivery of drugs to the central nervous system. Sehgal et al found that permeability of the fly BBB changes over the course of the day: night cycle, so an anti-epileptic works better at a specific time of day.<ref>{{cite journal |last1=Zhang |first1=Shirley L. |last2=Yue |first2=Zhifeng |last3=Arnold |first3=Denice M. |last4=Artiushin |first4=Gregory |last5=Sehgal |first5=Amita |title=A Circadian Clock in the Blood-Brain Barrier Regulates Xenobiotic Efflux |journal=Cell |date=March 2018 |volume=173 |issue=1 |pages=130–139.e10 |doi=10.1016/j.cell.2018.02.017 |pmid=29526461 |pmc=5866247 }}</ref> They have also mapped circuits that link the clock to behavioral activity.<ref>{{cite journal |last1=Cavanaugh |first1=Daniel J. |last2=Geratowski |first2=Jill D. |last3=Wooltorton |first3=Julian R.A. |last4=Spaethling |first4=Jennifer M. |last5=Hector |first5=Clare E. |last6=Zheng |first6=Xiangzhong |last7=Johnson |first7=Erik C. |last8=Eberwine |first8=James H. |last9=Sehgal |first9=Amita |title=Identification of a Circadian Output Circuit for Rest:Activity Rhythms in Drosophila |journal=Cell |date=April 2014 |volume=157 |issue=3 |pages=689–701 |doi=10.1016/j.cell.2014.02.024 |pmid=24766812 |pmc=4003459 }}</ref>

=== Sleep and immune function ===
Seeking to identify molecules that induce sleep, Toda et al conducted a genetic screen of >10,000 of fruit fly strains, and found one that drives sleep. This molecule, which they named nemuri, is an anti-microbial peptide. Its expression is switched on by infection or [[sleep deprivation]], and it promotes survival by killing bacteria and increasing sleep.<ref>{{cite journal |last1=Toda |first1=Hirofumi |last2=Williams |first2=Julie A. |last3=Gulledge |first3=Michael |last4=Sehgal |first4=Amita |title=A sleep-inducing gene, nemuri, links sleep and immune function in Drosophila |journal=Science |date=1 February 2019 |volume=363 |issue=6426 |pages=509–515 |doi=10.1126/science.aat1650 |pmid=30705188 |pmc=6505470 |bibcode=2019Sci...363..509T }}</ref><ref>{{cite news |last1=Lambert |first1=Jonathan |title=Sick And Tired? Scientists Find Protein That Puts Flies To Sleep And Fights Infection |url=https://www.npr.org/sections/health-shots/2019/01/31/690170468/sick-and-tired-scientists-find-protein-that-puts-flies-to-sleep-and-fights-infection |work=NPR |date=31 January 2019 }}</ref>

== Awards and positions ==

=== Positions ===
*Director, Chronobiology and Sleep Institute (CSI), Perelman School of Medicine, University of Pennsylvania, 2019-present
*Director of Penn Chronobiology Program, 2014-19
*[[Howard Hughes Medical Institute]] Investigator, 1997 – present
*John Herr Musser Professor of Neuroscience, Perelman School of Medicine, University of Pennsylvania
*Vice Chair of the Department of Neuroscience
*Co-Director of the Penn Medicine Neuroscience Center, 2008-2014
<ref>{{Cite web|url=http://www.upenn.edu/pennnews/current/peopleofpenn/amita-sehgal |title=Amita Sehgal |access-date=8 April 2015 |website=Penn Current |editor-last=Johnson |editor-first=Greg |archive-url=https://web.archive.org/web/20150908083239/http://www.upenn.edu/pennnews/current/peopleofpenn/amita-sehgal |archive-date=8 September 2015 }}</ref>

=== Awards ===
*Outstanding Scientific Achievement Award, [[Sleep Research Society]]
*[[Michael Stuart Brown|Michael S. Brown]] Junior Faculty Research Award
*[[Stanley Cohen (biochemist)|Stanley Cohen]] Senior Faculty Research Award
*Elected to the [[National Academy of Medicine]] (formerly Institute of Medicine), 2009
*Elected to the [[American Academy of Arts and Sciences]], 2011
*Elected Fellow of the [[American Association for the Advancement of Science]], 2016
*Elected to the [[National Academy of Sciences]], 2016<ref>{{citation|url=http://www.nasonline.org/news-and-multimedia/news/may-3-2016-NAS-Election.html|title=National Academy of Sciences Members and Foreign Associates Elected|department=News from the National Academy of Sciences|publisher=[[National Academy of Sciences]]|date=3 May 2016|access-date=2016-05-14|archive-url=https://web.archive.org/web/20160506052951/http://www.nasonline.org/news-and-multimedia/news/may-3-2016-NAS-Election.html|archive-date=6 May 2016}}.</ref>
*Switzer Prize from the [[David Geffen School of Medicine at UCLA]], 2020 <ref>{{Cite web|url=https://newsroom.ucla.edu/releases/david-geffen-school-of-medicine-names-2020-winner-of-switzer-prize-for-research-excellence|title=David Geffen School of Medicine at UCLA names 2020 Switzer Prize recipient|website=UCLA}}</ref>

== References ==
{{Reflist}}

{{Authority control}}

{{DEFAULTSORT:Sehgal, Amita}}
[[Category:Cornell University alumni]]
[[Category:Jawaharlal Nehru University alumni]]
[[Category:Living people]]
[[Category:Indian molecular biologists]]
[[Category:Delhi University alumni]]
[[Category:Indian women molecular biologists]]
[[Category:Year of birth missing (living people)]]
[[Category:Place of birth missing (living people)]]
[[Category:Chronobiologists]]
[[Category:Members of the United States National Academy of Sciences]]
[[Category:Women scientists from Delhi]]
[[Category:Perelman School of Medicine at the University of Pennsylvania faculty]]
[[Category:Members of the National Academy of Medicine]]
[[Category:Howard Hughes Medical Investigators]]

Amita Sehgal - Revision history

Gurushivam at 17:21, 18 February 2026