James Erickson

Associate Professor

Fax: 979-845-2891

3258 TAMU
Biological Sciences Building West
Room 348C

Biological Sciences Building West
Room 348

Joined the Department in 2003

  • B.S., 1981, University of California, Davis, Environmental Toxicology.
  • Ph.D., 1989, University of Wisconsin, Madison, Bacteriology.
  • Postdoctoral research, Princeton University and University of California, Berkeley.

Sex Determination and Threshold Responses in Development

Alternative developmental fates are often determined by small differences in the concentrations of signaling molecules. In many cases, cells respond to these signals within narrowly defined temporal windows and are unresponsive to the same signal molecules at other times in development. A number of aspects of Drosophila sex determination make it an ideal experimental system to study how strict temporal controls and small quantitative differences in protein concentration can elicit different developmental fates.

Sex is determined in Drosophila by the number of X chromosomes, with one X specifying male development and two specifying female. The dose of X chromosomes controls sex determination through its effects on the establishment promoter, SxlPe, of the regulatory gene Sex-lethal. Female development occurs as a consequence of Sxl being turned on in diplo-X animals while male development occurs in haplo-X animals because Sxl is left inactive. Although Sxl protein is required at all times to direct female differentiation, X chromosome dose affects Sxl expres ion only during a 30-40 min period in the pre-cellular embryo. After this time, Pe shuts off and Sxlis transcribed from a maintenance promoter, Pm, that operates in both sexes.

Genetic experiments have identified five elements on the X chromosome whose relative dose (one vs. two) is used to determine sex. These include the genes sisterlessA and -B, -C, runt, as well as Sxl itself. The sisA sisB and runt genes encode transcriptional activators of the bZIP, bHLH, and runt/AML class. The dose of these “counted” elements is measured with respect to a number of maternal and zygotically expressed proteins, some of which function as activators and some as inhibitors. We are studying the molecular interactions between the positively acting and inhibitory protein factors and their SxlPe promoter target. Our approach combines biochemistry with classical and molecular genetic analyses to identify novel molecules, and to characterize the protein/protein and protein/DNA interactions that regulate SxlPe. Given the ability to identify the key regulatory molecules, to study their expression, and to manipulate their levels and activity, in vitro, and in vivo; studies on Drosophila sex determination should prove ideal for understanding how transcriptional regulators of different classes can cooperate to generate sharp threshold responses.

  1. Chang, WH, Nguyen, TT, Hsu, CH, Bryant, KL, Kim, HJ, Ying, H et al.. KRAS-dependent cancer cells promote survival by producing exosomes enriched in Survivin. Cancer Lett. 2021;517 :66-77. doi: 10.1016/j.canlet.2021.05.031. PubMed PMID:34111513 PubMed Central PMC8324551.
  2. Chen, AM, Erzurum, SA, Chandler, DL, Hercinovic, A, Melia, BM, Bhatt, AR et al.. Overminus Lens Therapy for Children 3 to 10 Years of Age With Intermittent Exotropia: A Randomized Clinical Trial. JAMA Ophthalmol. 2021;139 (4):464-476. doi: 10.1001/jamaophthalmol.2021.0082. PubMed PMID:33662112 PubMed Central PMC7934080.
  3. Mahadeveraju, S, Jung, YH, Erickson, JW. Evidence That Runt Acts as a Counter-Repressor of Groucho During Drosophila melanogaster Primary Sex Determination. G3 (Bethesda). 2020;10 (7):2487-2496. doi: 10.1534/g3.120.401384. PubMed PMID:32457096 PubMed Central PMC7341146.
  4. Li, Y, Ramachandran, S, Nguyen, TT, Stalnecker, CA, Cerione, RA, Erickson, JW et al.. The activation loop and substrate-binding cleft of glutaminase C are allosterically coupled. J Biol Chem. 2020;295 (5):1328-1337. doi: 10.1074/jbc.RA119.010314. PubMed PMID:31871054 PubMed Central PMC6996896.
  5. Greene, KS, Lukey, MJ, Wang, X, Blank, B, Druso, JE, Lin, MJ et al.. SIRT5 stabilizes mitochondrial glutaminase and supports breast cancer tumorigenesis. Proc Natl Acad Sci U S A. 2019; :. doi: 10.1073/pnas.1911954116. PubMed PMID:31843902 PubMed Central PMC6936584.
  6. Lukey, MJ, Cluntun, AA, Katt, WP, Lin, MJ, Druso, JE, Ramachandran, S et al.. Liver-Type Glutaminase GLS2 Is a Druggable Metabolic Node in Luminal-Subtype Breast Cancer. Cell Rep. 2019;29 (1):76-88.e7. doi: 10.1016/j.celrep.2019.08.076. PubMed PMID:31577957 PubMed Central PMC6939472.
  7. Gao, Y, Hu, H, Ramachandran, S, Erickson, JW, Cerione, RA, Skiniotis, G et al.. Structures of the Rhodopsin-Transducin Complex: Insights into G-Protein Activation. Mol Cell. 2019;75 (4):781-790.e3. doi: 10.1016/j.molcel.2019.06.007. PubMed PMID:31300275 PubMed Central PMC6707884.
  8. Mateos, M, Silva, NO, Ramirez, P, Higareda-Alvear, VM, Aramayo, R, Erickson, JW et al.. Effect of heritable symbionts on maternally-derived embryo transcripts. Sci Rep. 2019;9 (1):8847. doi: 10.1038/s41598-019-45371-0. PubMed PMID:31222094 PubMed Central PMC6586653.
  9. Gao, Y, Erickson, JW, Cerione, RA, Ramachandran, S. Reconstitution of the Rhodopsin-Transducin Complex into Lipid Nanodiscs. Methods Mol Biol. 2019;2009 :317-324. doi: 10.1007/978-1-4939-9532-5_24. PubMed PMID:31152414 .
  10. Gao, Y, Erickson, JW, Cerione, RA, Ramachandran, S. Purification of the Rhodopsin-Transducin Complex for Structural Studies. Methods Mol Biol. 2019;2009 :307-315. doi: 10.1007/978-1-4939-9532-5_23. PubMed PMID:31152413 .
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