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Biosketch / Results /

Hyung Don Ryoo, Ph.D., D.Phil.

Associate Professor; Advsr Cellular Molecular Bio Trng Program; Co Dir CMB Training Program; Inst Lecturer-Cell Bio & Histology
Department of Cell Biology (Cell Biology) [1]

Contact Info

Address
550 First Avenue
Floor 6 Room 6102
Medical Science Building
New York, NY 10016

212-263-7257
HyungDon.Ryoo@nyumc.org

[2]

« Back to Results [6]

Education

1994-2000 — Columbia Univ, Graduate Education

« Back to Results [6]

Research Summary

Our laboratory is interested in understanding the basic mechanisms of apoptosis during animal development and in diseases. Our strategy is to use the genetic and cell biological tools of Drosophila as a model system.

Apoptosis is a morphologically distinct form of cell death that is programmed to sculpt body structures, maintain proper numbers of cells during development and eliminate damaged and potentially dangerous cells. Apoptosis is found defective in most cancers, and excess apoptosis underlies many neurodegenerative disorders. A critical event in apoptosis is the activation caspases, a family member of the Cysteine proteases that reside in living cells as inactive zymogens and activated in cells that undergo apoptosis. For proper apoptosis regulation, caspases are extensively regulated, both through its activators such as Apaf-1/cytochrome c and through its inhibitors such as IAPs (Inhibitor of Apoptosis Proteins). In Drosophila, various cell death stimuli converge on the transcriptional and post-transcriptional regulation of IAP inhibitors Reaper, Hid and Grim.

Our research program can be subdivided into two major areas. Our first area of interest is to understand the mechanism of caspase regulation. We have previously demonstrated that Drosophila IAP1 (DIAP1) acts as a ubiquitin-ligase that targets apical caspase Dronc in living cells, and undergoes auto-ubiquitylation during apoptosis (Ryoo et. al., 2002; Ryoo et. al., 2004). Furthermore, we showed that DIAP1 inhibition, which occurs in cells doomed to die, leads to the induction of secretory factors DPP and WG. In turn, these secreted factors promote the proliferation and growth of neighboring cells. We have proposed that this regulatory mechanism contributes to apoptosis-induced compensatory cell proliferation (Ryoo et. al., 2004). We plan to further investigate the mechanistic basis of coordination between apoptosis and cell proliferation with a special focus on Diap1 and caspases. Progress in this area may enhance our understanding of how tissue size is regulated during animal development and in cancer (Ryoo et. al., 2003).

Our second research program is aimed at understanding how endoplasmic stress (ER-stress) activates apoptosis. ER-stress is frequently caused by unfolded proteins in the ER, and is thought to be the cause of a wide variety of disorders, including alzheimer's disease, parkinson's disease, retinitis pigmentosa, multiple myeloma and diabetes. Although apoptosis is a pathologically relevant outcome of ER-stress, how caspases become activated under these conditions remains poorly characterized. We have begun investigating the Drosophila genes that make up the cellular response machinery to ER-stress, also known as the Unfolded Protein Response (UPR). Through this effort, we found that the Drosophila xbp1 mRNA undergoes unconventional splicing in response to ER-stress, similar to those found in other organisms. This property was used to generate an ER-stress sensor where GFP is expressed in frame only after xbp1 mRNA splicing. Significantly, xbp1 splicing and ER-chaperone induction occurs in the Drosophila model for the Autosomal Dominant Retinitis Pigmentosa (ADRP), where the expression of mutant rhodopsin-1 molecules leads to late onset retinal degeneration. These developments provide a basis to investigate how ER-stress activates apoptosis in Drosophila disease models (Ryoo et. al., 2007). Ongoing efforts aim to examine existing hypotheses and to identify new components linking ER-stress and caspase activation.

Research Documents

Apoptosis and stress response in Drosophila [7]

« Back to Results [6]

All data from NYU Health Sciences Library Faculty Bibliography — -

Contact:
http://hsl.med.nyu.edu/faculty-bibliography-search [8]

Drosophila p53 isoforms differentially regulate apoptosis and apoptosis-induced proliferation
Dichtel-Danjoy, M-L; Ma, D; Dourlen, P; Chatelain, G; Napoletano, F; Robin, M; Corbet, M; Levet, C; Hafsi, H; Hainaut, P; Ryoo, H D; Bourdon, J-C; Mollereau, B
2013 Jan;20(1):108-116, Cell death & differentiation
— id: 206302, year: 2013, vol: 20, page: 108, stat: Journal Article,

Compensatory proliferation and apoptosis-induced proliferation: a need for clarification
Mollereau, B; Perez-Garijo, A; Bergmann, A; Miura, M; Gerlitz, O; Ryoo, H D; Steller, H; Morata, G
2013 Jan;20(1):181-181, Cell death & differentiation
— id: 206292, year: 2013, vol: 20, page: 181, stat: Journal Article,

A modified UPR stress sensing system reveals a novel tissue distribution of IRE1/XBP1 activity during normal Drosophila development
Sone, Michio; Zeng, Xiaomei; Larese, Joseph; Ryoo, Hyung Don
2013 May;18(3):307-319, Cell stress chaperones
— id: 304812, year: 2013, vol: 18, page: 307, stat: Journal Article,

Drosophila BRUCE inhibits apoptosis through non-lysine ubiquitination of the IAP-antagonist REAPER
Domingues, C; Ryoo, H D
2012 Mar;19(3):470-477, Cell death & differentiation
— id: 158637, year: 2012, vol: 19, page: 470, stat: Journal Article,

CDK5 and MEKK1 mediate pro-apoptotic signalling following endoplasmic reticulum stress in an autosomal dominant retinitis pigmentosa model
Kang, Min-Ji; Chung, Jaehoon; Ryoo, Hyung Don
2012 Apr;14(4):409-415, Nature cell biology
— id: 163572, year: 2012, vol: 14, page: 409, stat: Journal Article,

Pro-apoptotic signaling pathway by CDK5 and MEKK1
Ryoo, Hyung Don
2012 May;11(9):1746-1747, Cell cycle
— id: 166825, year: 2012, vol: 11, page: 1746, stat: Journal Article,

The role of apoptosis-induced proliferation for regeneration and cancer
Ryoo, Hyung Don; Bergmann, Andreas
2012 ;4(8):a008797-a008797, Cold Spring Harbor perspectives in biology
— id: 174400, year: 2012, vol: 4, page: a008797, stat: Journal Article,

Drosophila IAP antagonists form multimeric complexes to promote cell death
Sandu, Cristinel; Ryoo, Hyung Don; Steller, Hermann
2010 Sep 20;190(6):1039-1052, Journal of cell biology
— id: 133803, year: 2010, vol: 190, page: 1039, stat: Journal Article,

Suppression of retinal degeneration in Drosophila by stimulation of ER-associated degradation
Kang, Min-Ji; Ryoo, Hyung Don
2009 Oct 6;106(40):17043-17048, Proceedings of the National Academy of Sciences of the United States of America
— id: 104349, year: 2009, vol: 106, page: 17043, stat: Journal Article,

ER stress protects from retinal degeneration
Mendes, CS; Levet, C; Chatelain, G; Dourlen, P; Fouillet, A; Dichtel-Danjoy, ML; Gambis, A; Ryoo, HD; Steller, H; Mollereau, B
2009 MAY 6 ;28(9):1296-1307, EMBO journal
— id: 99178, year: 2009, vol: 28, page: 1296, stat: Journal Article,

STAT92E is a positive regulator of Drosophila inhibitor of apoptosis 1 (DIAP/1) and protects against radiation-induced apoptosis
Betz, Aurel; Ryoo, Hyung Don; Steller, Hermann; Darnell, James E Jr
2008 Sep 16;105(37):13805-13810, Proceedings of the National Academy of Sciences of the United States of America
— id: 90753, year: 2008, vol: 105, page: 13805, stat: Journal Article,

Regulation of the Drosophila apoptosome through feedback inhibition
Shapiro, Peter J; Hsu, Hans H; Jung, Heekyung; Robbins, Edith S; Ryoo, Hyung Don
2008 Dec;10(12):1440-1446, Nature cell biology
— id: 90751, year: 2008, vol: 10, page: 1440, stat: Journal Article,

Ero1L, a thiol oxidase, is required for Notch signaling through cysteine bridge formation of the Lin12-Notch repeats in Drosophila melanogaster
Tien, An-Chi; Rajan, Akhila; Schulze, Karen L; Ryoo, Hyung Don; Acar, Melih; Steller, Hermann; Bellen, Hugo J
2008 Sep 22;182(6):1113-1125, Journal of cell biology
— id: 90752, year: 2008, vol: 182, page: 1113, stat: Journal Article,

Regulation of the Drosophila ubiquitin ligase DIAP1 is mediated via several distinct ubiquitin system pathways
Herman-Bachinsky, Y; Ryoo, HD; Ciechanover, A; Gonen, H
2007 APR ;14(4):861-871, Cell death & differentiation
— id: 71623, year: 2007, vol: 14, page: 861, stat: Journal Article,

Unfolded protein response in a Drosophila model for retinal degeneration
Ryoo, Hyung Don; Domingos, Pedro M; Kang, Min-Ji; Steller, Hermann
2007 Jan 10;26(1):242-252, EMBO journal
— id: 70029, year: 2007, vol: 26, page: 242, stat: Journal Article,

Unfolded protein response in Drosophila: why another model can make it fly
Ryoo, Hyung Don; Steller, Hermann
2007 Apr;6(7):830-835, Cell cycle
— id: 71606, year: 2007, vol: 6, page: 830, stat: Journal Article,

Developmental apoptosis
Ryoo HD; Steller H
Apoptosis in health and disease : clinical and therapeutic aspects Ca