Lynn Cooley, Ph.D.

Professor of Genetics and Cell Biology Director of Combined Program in the Biological & Biomedical Sciences
Cooley lab website FlyTrap website Phone: (203) 785-5067 Lab: (203) 737-2953/2675 Fax: (203) 785-6333 e-mail: lynn.cooley@yale.edu		Department of Genetics Yale University School of Medicine 333 Cedar Street PO Box 208005 New Haven, CT 06520-8005 <Courier Address> 333 Cedar Street, SHM I-363 New Haven, CT 06510-3206

---

Our research is focused on the cell biology of Drosophila oogenesis during which maternal products for directing early embryogenesis are deposited in oocytes. We have relied on female sterile mutants in which the movement of cytoplasm from nurse cells into oocytes via ring canals is disrupted. These mutants have led to the discovery that egg chamber development requires precise control of cytoskeletal structures in the nurse cells. Recently, additional insight into oocyte growth has come from a collection of fly lines expressing Green Fluorescent Protein fused to endogenous proteins.

Ring canals. Several cytoplasm transport mutants revealed protein components of germline intercellular junctions called ring canals that connect nurse cells to each other and to the oocyte. We have found that growth of ring canals during development requires actin dynamics similar to what occurs at the leading edge of motile cells. Current studies focus on the establishment of the ring canal actin cytoskeleton early in oogenesis, and the regulation of actin filament organization and stability during oocyte growth. In addition, we are studying the function and prevalence of ring canals in somatic cells.

Oocyte ER organization. One mutant we are studying affects the organization of the endoplasmic reticulum in oocytes. Just before the oocyte begins yolk uptake, the ER becomes concentrated subcortically in order to facilitate presentation of yolk receptor to the plasma membrane. When this ER reorganization fails to occur, yolk uptake is reduced and the oocyte surface organization is disrupted. One protein required for ER reorganization is a small tetraspan protein called Jagunal present in the ER. Ongoing work with Jagunal will help to understand how stage-specific ER clustering occurs.

Flytrap. We have carried out a large-scale protein-trapping screen in which fusions between Green Fluorescent Protein and endogenous proteins are generated (see http://flytrap.med.yale.edu). The cellular and subcellular patterns of GFP-fusion protein expression provide instant insight into protein function. Since the GFP coding sequence is introduced by a transposon, we can identify the trapped protein by sequencing genomic DNA flanking the insertion site. The expression patterns along with gene sequences provide a powerful starting point for genetic and functional analyses of proteins used during development.

Polarized protein transport. The nurse cells of egg chambers provide the vast majority of maternal components to growing oocytes, including key mRNAs that encode polarity-determining proteins. From the protein-trap screen we have found that a specific subset of proteins synthesized in nurse cells is highly enriched in oocytes starting very early in oogenesis, and many of these are predicted to bind mRNA. We are investigating whether these polarized proteins play a role in mRNA transport to the

 

Figure A:  Stage 10 egg chamber. Actin associated with plasma membranes and ring canals is labeled in red and nuclei are blue.
Figure B:  A single ring canal embedded in surrounding plasma membrane. Actin is red and HtsRC, a ring canal-specific protein, is green.

Selected Publications

Click for PDF

Petrella, L., Smith-Leiker, T. and Cooley, L. The Ovhts polyprotein produces fusome and ring canal proteins required for Drosophila oogenesis. (2007) Development 134: 703-712.

Quiñones-Coello, A.T., Petrella, L.N., Ayers, K., Melillo, A., Mazzalupo, S., Hudson, A.M., Wang, S., Castiblanco, C., Buszczak, M., Hoskins, R.A., and Cooley, L. (2007) Exploring strategies for protein trapping in Drosophila. Genetics 175: 1089-1104.

Lee, S. and Cooley, L. (2007) jagunal is required for reorganizing the endoplasmic reticulum during Drosophila oogenesis.  J. Cell Biol. 176: 941-952.

Mazzalupo, S. and Cooley, L. (2006) Illuminating the role of caspases during Drosophila oogenesis.  Cell Death Differen. 13: 1950-1959.

Mermall, V., Bonafé, N., Jones, L., Sellers, J.R., Cooley, L, and Mooseker, M.S. (2005) Drosophila Myosin V is required for larval development and spermatid individualization.  Devel. Biol. 286: 238-255.