Faculty

The eggs of most organisms contain molecular asymmetries that function critically in the formation of the embryonic body pattern. In Drosophila, for example, proteins that direct the formation of the embryo's head and tail are prelocalized to the egg's anterior and posterior ends, respectively, during oogenesis. My lab is interested in understanding how such asymmetries arise. This interest has led us into an investigation of mRNA localization, which we now know plays a key role in the localization of many proteins in a wide variety of animal cells.

More than a dozen localized mRNAs have been identified in the Drosophila oocyte. The localization of most of these involves unidirectional transport along microtubule tracks.

We have used a transgenic fly assay system to identify a small, stem-loop sequence in two localized mRNAs (K10 and orb) that mediate association with a microtubule-based motor protein. We are currently using a variety of genetic, molecular and biochemical techniques to identify the proteins that bind to this sequence. Related projects include a study of the mechanisms that prevent the translation of mRNAs during localization, and the identification of genes that control microtubule organization.

In another project, we have shown that the localization of oskar mRNA to the oocyte’s posterior pole requires Rab11, a protein previously known for its role in vescile trafficking. We are currently investigating the idea that oskar and possibly other mRNAs are moved through cells by hitching a ride on membrane vesicles.

Representative Publications

• Cohen RS and Meselson M. 1984. Inducible Transcription and Puffing in D. melanogaster transformed with hsp70-phage lambda hybrid genes. PNAS 81, 5509–5513.
• Cohen RS and Meselson M. 1985. Separate Regulatory Elements for the Heat-Inducible and Ovarian Expression of the Drosophila hsp26 Gene. Cell 42, 737–746.
• Cohen RS and Meselson M. 1988. Periodic Interactions of hsp70 Transcriptional Control Elements. Nature 332, 856–858.
• Frank LH, Cheung HK, and Cohen RS. 1992. Identification and characterization of Drosophila female germ line transcriptional control elements. Development 114: 481–491.
• Cheung HK, Serano TL and Cohen RS. 1992. Evidence for a highly selective RNA transport system and its role in establishing the dorsoventral axis of the Drosophila egg. Development 114: 653–661.
• Serano TL, Cheung HK, Frank LF and Cohen RS. 1994. P element transformation vectors for studying Drosophila melanogaster oogenesis and early embryogenesis. Gene 138: 181–186.
• Cohen RS and Serano TL. 1995. mRNA localization and function of the Drosophila fs(1)K10 gene. In: localized RNAs (ed. H.D. Lipshitz). pp 99-112. R.G. Landes Co.:Austin.
• Serano TL and Cohen RS. 1995. Gratuitous mRNA localization in the Drosophila oocyte. Development 121: 3013–3021.
• Serano TL and Cohen RS 1995. A single small stem-loop structure mediates K10 mRNA localization. Development 121: 3809–3818.
• Serano TL, Karlin-McGinness, M and Cohen RS. 1995. The role of fs(1)K10 in the localization of the mRNA of the TGFa homolog gurken within the Drosophila oocyte. Mechanisms of Development, 51: 183–192.
• Karlin-McGinness, M, Serano, TL and Cohen RS 1996. Comparative analysis of the kinetics and dynamics of K10, bicoid, and oskar mRNA localization in the Drosophila oocyte. Developmental Genetics 19: 238–248.
• Saunders, C and Cohen, RS. 1999. The role of oocyte transcription, the 5'UTR, and translation repression and depression in Drosophila gurken mRNA and protein localization. Molecular Cell 3, 43–54.
• Dollar GL, Struckhoff E, Michaud J and Cohen RS. 2002. Gurken-independent polarization of the Drosophila oocyte; Rab11-mediated organization of the posterior pole. Development 129, 517–526.
• Cohen RS. 2002. Oocyte Patterning: Dynein and Kinesin, Inc. Current Biology 12, R797-799.
• Cohen RS. 2003. Halo: A Guiding Light for Transport. Current Biology, 13, R869–870.
• Cohen RS. 2005. The role of membranes and membrane trafficking in RNA localization. Biol. Cell 97, 5–18.
• Cohen, RS, Zhang S, Dollar, GL. 2005. The positional, structural and sequence requirements of the Drosophila TLS RNA localization element. RNA 11, 1017–1029.
• Cohen, RS. 2005. Microtubule Motors: LSD2 Trips the Toggle. Current Biology in press.

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