Laura A. Lee, M.D., Ph.D.
Assistant Professor of Cell and Developmental Biology
Vanderbilt University Medical Center
1161 21st Ave, U-4227 Learned Lab
Nashville, TN 37232-2175
Proper control of the cell cycle is essential for the formation and survival of multi-cellular organisms, and derangements in cell-cycle regulation are often observed in pathological states such as cancer and birth defects. My laboratory uses Drosophila melanogaster to study cell-cycle regulation during the development of a multi-cellular organism. The high degree of functional conservation of genes combined with the superb genetics and cell biology of Drosophila make it an attractive model organism.
Drosophila genetics is the major tool we use to identify and characterize new genes that regulate the cell cycle. We complement our genetic approaches with both cell biology and biochemistry, including genome-scale biochemical screening. We also utilize cultured mammalian cells and Xenopus embryos (in collaboration with Dr. Ethan Lee) to further characterize new genes identified in Drosophila that play conserved roles in cell-cycle regulation in higher organisms.
CELL CYCLE REGULATION BY DROSOPHILA MCPH1
Mutations in the human microcephalin (MCPH1) gene result in primary microcephaly ("small head" in Greek), a developmental condition in which cerebral cortex size is severely reduced. We identified mcph1, the Drosophila homolog of human MCPH1, in a genetic screen for cell-cycle regulators. Embryos from null mcph1 females undergo mitotic arrest as a consequence of mitotic entry in the face of DNA defects. Current efforts are directed towards identifying the pathways in which MCPH1 participates by using both genetic and biochemical approaches.
NOPO IS A CANDIDATE E3 UBIQUITIN LIGASE THAT CONTROLS EARLY EMBRYONIC CELL CYCLE
We also identified no poles (nopo) in our genetic screen for cell-cycle regulators in the early embryo. Like mcph1, embryos from null nopo females undergo mitotic arrest secondary to mitotic entry with damaged or incompletely replicated DNA. nopo-derived embryos exhibit a high frequency of spindles that lack centrosomes (hence the name "no poles") and misaligned chromosomes. The predicted NOPO protein contains a RING domain and is a candidate E3 ubiquitin ligase. Current efforts are directed towards identifying NOPO targets using both genetic and biochemical approaches.
MAT89Bb IS REQUIRED FOR SPERMATOGENESIS
We identified Mat89Bb as a substrate of PNG, a kinase that coordinates cell cycles in early embryos of Drosophila. Unexpectedly, we have found by mutant analysis that Mat89Bb is required for male fertility. We observe defects in coupling between the nucleus and centrosomes throughout spermatogenesis in Mat89Bb males leading to defects in meiotic spindle assembly and chromosome segregation. Our data indicate that these defects are due to lack of proper localization of dynein, a microtubule motor, to the nuclear periphery in Mat89Bb spermatocytes. Current efforts are directed towards understanding the basis for regulation of dynein by Mat89Bb.
- Jodoin, JN, Shboul, M, Sitaram, P, Zein-Sabatto, H, Reversade, B, Lee, E, Lee, LA Human Asunder promotes dynein recruitment and centrosomal tethering to the nucleus at mitotic entry. Mol Biol Cell, 23(24), 4713-24, 2012.
- Sitaram, P, Anderson, MA, Jodoin, JN, Lee, E, Lee, LA Regulation of dynein localization and centrosome positioning by Lis-1 and asunder during Drosophila spermatogenesis. Development, 139(16), 2945-54, 2012.
- Hang, BI, Thorne, CA, Robbins, DJ, Huppert, SS, Lee, LA, Lee, E Screening for small molecule inhibitors of embryonic pathways: sometimes you gotta crack a few eggs. Bioorg Med Chem, 20(6), 1869-77, 2012.
- Hanson, AJ, Wallace, HA, Freeman, TJ, Beauchamp, RD, Lee, LA, Lee, E XIAP monoubiquitylates Groucho/TLE to promote canonical Wnt signaling. Mol Cell, 45(5), 619-28, 2012.
- Thorne, CA, Lafleur, B, Lewis, M, Hanson, AJ, Jernigan, KK, Weaver, DC, Huppert, KA, Chen, TW, Wichaidit, C, Cselenyi, CS, Tahinci, E, Meyers, KC, Waskow, E, Orton, D, Salic, A, Lee, LA, Robbins, DJ, Huppert, SS, Lee, E A biochemical screen for identification of small-molecule regulators of the Wnt pathway using Xenopus egg extracts. J Biomol Screen, 16(9), 995-1006, 2011.
- Jernigan, KK, Cselenyi, CS, Thorne, CA, Hanson, AJ, Tahinci, E, Hajicek, N, Oldham, WM, Lee, LA, Hamm, HE, Hepler, JR, Kozasa, T, Linder, ME, Lee, E Gbetagamma activates GSK3 to promote LRP6-mediated beta-catenin transcriptional activity. Sci Signal, 3(121), ra37, 2010.
- Thorne, CA, Hanson, AJ, Schneider, J, Tahinci, E, Orton, D, Cselenyi, CS, Jernigan, KK, Meyers, KC, Hang, BI, Waterson, AG, Kim, K, Melancon, B, Ghidu, VP, Sulikowski, GA, LaFleur, B, Salic, A, Lee, LA, Miller, DM, Lee, E Small-molecule inhibition of Wnt signaling through activation of casein kinase 1Î±. Nat Chem Biol, 6(11), 829-36, 2010.
- Anderson, MA, Jodoin, JN, Lee, E, Hales, KG, Hays, TS, Lee, LA Asunder is a critical regulator of dynein-dynactin localization during Drosophila spermatogenesis. Mol Biol Cell, 20(11), 2709-21, 2009.
- Merkle, JA, Rickmyre, JL, Garg, A, Loggins, EB, Jodoin, JN, Lee, E, Wu, LP, Lee, LA no poles encodes a predicted E3 ubiquitin ligase required for early embryonic development of Drosophila. Development, 136(3), 449-59, 2009.
- Cselenyi, CS, Jernigan, KK, Tahinci, E, Thorne, CA, Lee, LA, Lee, E LRP6 transduces a canonical Wnt signal independently of Axin degradation by inhibiting GSK3''s phosphorylation of beta-catenin. Proc Natl Acad Sci U S A, 105(23), 8032-7, 2008.
- Von Stetina, JR, Tranguch, S, Dey, SK, Lee, LA, Cha, B, Drummond-Barbosa, D alpha-Endosulfine is a conserved protein required for oocyte meiotic maturation in Drosophila. Development, 135(22), 3697-706, 2008.
- Tahinci, E, Thorne, CA, Franklin, JL, Salic, A, Christian, KM, Lee, LA, Coffey, RJ, Lee, E Lrp6 is required for convergent extension during Xenopus gastrulation. Development, 134(22), 4095-106, 2007.
- Rickmyre, JL, Dasgupta, S, Ooi, DL, Keel, J, Lee, E, Kirschner, MW, Waddell, S, Lee, LA The Drosophila homolog of MCPH1, a human microcephaly gene, is required for genomic stability in the early embryo. J Cell Sci, 120(Pt 20), 3565-77, 2007.
- Greenstein, D, Lee, LA Oocyte-to-embryo transition: kinase cabal plots regime change. Curr Biol, 16(3), R93-5, 2006.
- Lee, Laura A, Lee, Ethan, Anderson, Michael A, Vardy, Leah, Tahinci, Emilios, Ali, Siraj M, Kashevsky, Helena, Benasutti, Matt, Kirschner, Marc W, Orr-Weaver, Terry L Drosophila Genome-Scale Screen for PAN GU Kinase Substrates Identifies Mat89Bb as a Cell Cycle Regulator. Dev Cell, 8(3), 435-42, 2005.
- Lee, Laura A, Orr-Weaver, Terry L Regulation of cell cycles in Drosophila development: intrinsic and extrinsic cues. Annu Rev Genet, 37545-78, 2003.
- Lee, Laura A, Van Hoewyk, Douglas, Orr-Weaver, Terry L The Drosophila cell cycle kinase PAN GU forms an active complex with PLUTONIUM and GNU to regulate embryonic divisions. Genes Dev, 17(23), 2979-91, 2003.
- Lee, L A, Elfring, L K, Bosco, G, Orr-Weaver, T L A genetic screen for suppressors and enhancers of the Drosophila PAN GU cell cycle kinase identifies cyclin B as a target.. Genetics, 158(4), 1545-56, 2001.
- Hofmann, S L, Lee, L A, Lu, J Y, Verkruyse, L A Palmitoyl-protein thioesterase and the molecular pathogenesis of infantile neuronal ceroid lipofuscinosis.. Neuropediatrics, 28(1), 27-30, 1997.
- Hepler, J R, Biddlecome, G H, Kleuss, C, Camp, L A, Hofmann, S L, Ross, E M, Gilman, A G Functional importance of the amino terminus of Gq alpha.. J Biol Chem, 271(1), 496-504, 1996.
- Camp, L A, Hofmann, S L Assay and isolation of palmitoyl-protein thioesterase from bovine brain using palmitoylated H-Ras as substrate.. Methods Enzymol, 250336-47, 1995.
- Vesa, J, Hellsten, E, Verkruyse, L A, Camp, L A, Rapola, J, Santavuori, P, Hofmann, S L, Peltonen, L Mutations in the palmitoyl protein thioesterase gene causing infantile neuronal ceroid lipofuscinosis.. Nature, 376(6541), 584-7, 1995.
- Camp, L A, Verkruyse, L A, Afendis, S J, Slaughter, C A, Hofmann, S L Molecular cloning and expression of palmitoyl-protein thioesterase.. J Biol Chem, 269(37), 23212-9, 1994.
- Camp, L A, Chauhan, P, Farrar, J D, Lehrman, M A Defective mannosylation of glycosylphosphatidylinositol in Lec35 Chinese hamster ovary cells.. J Biol Chem, 268(9), 6721-8, 1993 .
- Camp, L A, Hofmann, S L Purification and properties of a palmitoyl-protein thioesterase that cleaves palmitate from H-Ras.. J Biol Chem, 268(30), 22566-74, 1993.
- De Valoir, T., Tucker, M. A., Belikoff, E. J., Camp, L. A., Bolduc, C., Beckingham, K. "A second maternally expressed Drosophila gene encodes a putative RNA helicase of the "DEAD box" family.." Proc Natl Acad Sci U. S. A., 88(6), 2113-7, 1991.