# Kwang‐Wook Choi
**Kwang-Wook Choi** (최광욱) is a South Korean molecular geneticist who studies how organs are patterned and sized, using the fruit fly *Drosophila melanogaster* as his model organism. He is an active Emeritus Professor in the Department of Biological Sciences at the [Korea Advanced Institute of Science and Technology](https://www.edgepedia.org/korea-advanced-institute-of-science-and-technology) (KAIST).[1](https://koasas.kaist.ac.kr/researcher-profile?perno=6227) Over three decades his laboratory has worked on pattern formation, cell polarity, and cell fate specification in the developing *Drosophila* eye, and on genetic pathways that control organ growth.[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) According to a 1994 study in *Cell*, rotation of photoreceptor clusters in the developing *Drosophila* eye requires the *nemo* gene, and he is also known for showing that the peripodial membrane sends essential patterning signals to the eye disc and for establishing *Drosophila* [TCTP](https://www.edgepedia.org/translationally-controlled-tumour-protein) as a direct regulator of the Rheb GTPase (enzyme that switches cell signaling on/off by binding GTP) in the growth-control pathway.
| Key facts | |
|---|---|
| Field | Molecular genetics of *Drosophila* eye development and organ growth control[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) |
| Current position | Emeritus Professor, Department of Biological Sciences, KAIST[1](https://koasas.kaist.ac.kr/researcher-profile?perno=6227) |
| Training | BS in microbial genetics, Seoul National University; PhD in Biochemistry, Princeton University (thesis supervisor Chip Quinn)[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) |
| Postdoctoral training | Eye development in *Drosophila* with Seymour Benzer at Caltech[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) |
| Signature work | "Novel Signaling from the Peripodial Membrane Is Essential for Eye Disc Patterning in *Drosophila*", *Cell*, 2000[3](https://doi.org/10.1016/s0092-8674(00)00124-0) |
| Growth-control finding | *Drosophila* TCTP is a direct regulator of Rheb, a GTPase in the TSC pathway (*Nature*, 2007)[4](https://ideas.repec.org/a/nat/nature/v445y2007i7129d10.1038_nature05528.html) |
| Honor | Michael DeBakey Award for Excellence in Research, Baylor College of Medicine[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) |
## Education and career
Choi earned a BS in microbial genetics from [Seoul National University](https://www.edgepedia.org/seoul-national-university) and a PhD in [Biochemistry](https://www.edgepedia.org/biochemistry) from Princeton University, where he learned *Drosophila* neurogenetics from his thesis supervisor Chip Quinn.[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) As a postdoctoral fellow he studied eye development in *Drosophila* with [Seymour Benzer](https://www.edgepedia.org/seymour-benzer) at the California Institute of Technology.[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) His 1994 *Cell* paper on photoreceptor rotation was done at Caltech's Division of Biology and credits both Choi and Benzer.[5](https://pubmed.ncbi.nlm.nih.gov/8033204/) • [6](https://doi.org/10.1016/0092-8674(94)90579-7)
He then joined the faculty of the Department of Molecular and Cellular Biology at [Baylor College of Medicine](https://www.edgepedia.org/baylor-college-of-medicine), where he was an associate professor of molecular and cellular biology at the time of his 2007 *Nature* paper.[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) • [7](https://www.sciencedaily.com/releases/2007/02/070220182832.htm) After 14 years at Baylor he returned to Korea as Chair of the Bio-Department at KAIST.[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) He now holds emeritus status in KAIST's Department of Biological Sciences.[1](https://koasas.kaist.ac.kr/researcher-profile?perno=6227)
## The nemo gene and photoreceptor rotation
The *Drosophila* eye is a hexagonal array of photoreceptor cell clusters, the ommatidia. During normal morphogenesis, clusters in the dorsal and ventral halves of the eye disc rotate 90 degrees in opposite directions, producing a mirror-image arrangement.[5](https://pubmed.ncbi.nlm.nih.gov/8033204/) In the *nemo* (*nmo*) mutant, clusters make an initial turn of about 45 degrees, but further rotation toward the normal 90 degrees is blocked.[5](https://pubmed.ncbi.nlm.nih.gov/8033204/) The *nmo* gene encodes a serine/threonine protein kinase homolog, indicating that this kinase is required to initiate the second step of rotation.[5](https://pubmed.ncbi.nlm.nih.gov/8033204/) A separate mutant, *roulette*, shows excessive rotation, and this defect is suppressed by *nmo*, placing *nmo* upstream in a pathway that regulates rotation.[5](https://pubmed.ncbi.nlm.nih.gov/8033204/) An NIH grant record from his Baylor laboratory states that the dorso-ventral mirror image is established as photoreceptor clusters rotate 90 degrees clockwise or counter-clockwise depending on each cluster's dorso-ventral polarity, and lists isolating genes downstream of *nemo* in the rotation pathway among its aims.[8](https://grantome.com/grant/NIH/R29-EY011110-03)
## Representative work
Novel Signaling from the Peripodial Membrane Is Essential for Eye Disc Patterning in *Drosophila* (*Cell*, published 1 October 2000) is the work that best stands for his eye-development program. Choi, at Baylor College of Medicine, was the corresponding author.[3](https://doi.org/10.1016/s0092-8674(00)00124-0) It showed that the peripodial membrane, the epithelial layer overlying the eye disc, provides signaling essential for patterning the disc beneath it.
## The TCTP growth-control program at KAIST
Choi's second major line of work concerns Translationally Controlled Tumor Protein (TCTP). His 2007 *Nature* paper reported genetic and biochemical evidence in *Drosophila* that TCTP is a direct regulator of Rheb, a Ras superfamily GTPase that is part of the TSC pathway, making TCTP a potential therapeutic target for tuberous sclerosis.[4](https://ideas.repec.org/a/nat/nature/v445y2007i7129d10.1038_nature05528.html) A companion addendum by Choi and a co-author stated that *Drosophila* TCTP displays guanine nucleotide exchange factor (GEF) activity toward Rheb and is essential for Rheb activation in organ growth, tightly linking dTCTP to the Rheb-TOR pathway.[9](https://doi.org/10.4161/cam.1.3.4901) The physiological stakes were direct: flies with only a little TCTP are very small, and complete knockout of TCTP function in the eye results in no eyes.[7](https://www.sciencedaily.com/releases/2007/02/070220182832.htm)
The cancer connection comes from the same protein. TCTP is over-expressed in cancer cells, and reducing TCTP levels made tumor cells revert to normal in the laboratory, although excess TCTP did not cause tumors in flies.[7](https://www.sciencedaily.com/releases/2007/02/070220182832.htm) A Springer chapter on TCTP function in organ growth, co-authored by Choi, surveys this line of work.[10](https://doi.org/10.1007/978-3-319-67591-6_8)
At KAIST the program broadened. In September 2016 the department announced a *Nature Communications* paper showing that Tctp binds the Brahma (Brm) chromatin remodeler to negatively modulate its activity; Tctp mutants show abnormally high transcription of many genes and transposons, and Tctp promotes the stability of repeated sequences such as rDNA and pericentromeric heterochromatin by opposing Brm function.[11](https://bio.kaist.ac.kr/index.php?document_srl=15256&mid=bio_news) A second 2016 *Nature Communications* paper, with Choi as corresponding author, showed that 14-3-3 proteins physically interact with Tctp and Rheb, and that knocking down both 14-3-3 isoforms abolishes Tctp–Rheb binding and disrupts organ development; the same paper records that human Tctp restores the growth defects of *Drosophila* Tctp knockdown, and that *Drosophila* Tctp rescues embryonic lethality in *Arabidopsis* Tctp loss-of-function mutants, indicating functional conservation across species.[12](https://doi.org/10.1038/ncomms11501) In 2022, a paper with Choi as corresponding author at KAIST showed that Tctp regulates the level and localization of Foxo for cell growth in *Drosophila*.[13](https://doi.org/10.1038/s41420-022-00937-2)
## Funding, honors and service
At Baylor, Choi held a grant from the National Eye Institute, "Genetic Control of Symmetry in the *Drosophila* Eye", which, according to the grant record, ran from 1 August 1995 to 31 July 2000 in the Department of Anatomy/Cell Biology.[8](https://grantome.com/grant/NIH/R29-EY011110-03) The 2007 TCTP work was also funded by the National Institutes of Health.[7](https://www.sciencedaily.com/releases/2007/02/070220182832.htm) He received the Michael DeBakey Award for Excellence in Research at Baylor, and he served as Chair of the Asia-Pacific Drosophila Board, organizing the Asia-Pacific Drosophila Research Conference in Seoul.[2](https://link.springer.com/book/10.1007/978-981-97-0830-7)
## Recent developments
Choi has published a book with Springer, *Genetic Studies in Model Organisms: From Classical to Modern Genetics*, written from his own career in *Drosophila* genetics; in it he credits Chip Quinn as his thesis supervisor and Seymour Benzer as his postdoctoral mentor.[2](https://link.springer.com/book/10.1007/978-981-97-0830-7) He remains listed as an active Emeritus Professor in KAIST's Department of Biological Sciences.[1](https://koasas.kaist.ac.kr/researcher-profile?perno=6227)
## References
1. [Choi, Kwang-Wook researcher profile, KOASAS (KAIST)](https://koasas.kaist.ac.kr/researcher-profile?perno=6227)
2. [Genetic Studies in Model Organisms: From Classical to Modern Genetics, Springer](https://link.springer.com/book/10.1007/978-981-97-0830-7)
3. https://doi.org/10.1016/s0092-8674(00)00124-0
4. [Drosophila TCTP is essential for growth and proliferation through regulation of dRheb GTPase, Nature](https://ideas.repec.org/a/nat/nature/v445y2007i7129d10.1038_nature05528.html)
5. [Rotation of photoreceptor clusters in the developing Drosophila eye requires the nemo gene, PubMed](https://pubmed.ncbi.nlm.nih.gov/8033204/)
6. https://doi.org/10.1016/0092-8674(94)90579-7
7. [Protein Key To Organ Growth, ScienceDaily](https://www.sciencedaily.com/releases/2007/02/070220182832.htm)
8. [Genetic Control of Symmetry in the Drosophila Eye, NIH R29-EY011110-03](https://grantome.com/grant/NIH/R29-EY011110-03)
9. [To Cease or To Proliferate, Cell Adhesion & Migration](https://doi.org/10.4161/cam.1.3.4901)
10. [Function of Translationally Controlled Tumor Protein in Organ Growth, Springer chapter](https://doi.org/10.1007/978-3-319-67591-6_8)
11. [최광욱 교수, 홍성태 박사 Nature Communications 논문 게재, KAIST Department of Biological Sciences](https://bio.kaist.ac.kr/index.php?document_srl=15256&mid=bio_news)
12. [14-3-3 proteins regulate Tctp–Rheb interaction for organ growth in Drosophila, Nature Communications](https://doi.org/10.1038/ncomms11501)
13. [Tctp regulates the level and localization of Foxo for cell growth in Drosophila, Cell Death & Discovery](https://doi.org/10.1038/s41420-022-00937-2)
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