Roy M. Long, PhD
Associate Professor
Microbiology and Molecular Genetics
Medical College of Wisconsin
Research Focus: RNA Localization in Yeast
PhD: Pennsylvania State University (1994) Biological Chemistry
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Using genetic, biochemical and cell biological approaches in the yeast S. cerevisiae, my laboratory is interested in studying mechanistic details of RNA localization, a process which post-transcriptionally regulates gene expression. In yeast ASH1 mRNA is localized to the distal end of the daughter cell during anaphase of the cell cycle, resulting in the exclusive deposition of Ash1p in daughter nuclei. Ash1p is a transcriptional repressor, and asymmetric sorting of Ash1p results in asymmetric regulation of transcription.
We have identified four cis-acting localization elements in the ASH1 mRNA sufficient to localize a heterologous reporter mRNA to daughter cells. One of these elements resides in the 3'-untranslated region (3-UTR) while the remaining three elements reside in the coding region of the ASH1 mRNA. Besides these cis-acting elements, five trans-acting factors (SHE1-5) and the actin cytoskeleton are required for localization of ASH1 mRNA. Our laboratory has focused on deciphering mechanistic details related to She1p, She2p and She3p. We demonstrated that She1p is type V myosin (Myo4p) that directly transports ASH1 mRNA containing particles to daughter cells. We also reported that She2p is an RNA-binding protein that directly interacts with each of the ASH1 cis-acting localization elements. Since She3p has the ability to interact with both Myo4p and She2p, we hypothesized that She3p functions to interface Myo4p with the She2p-ASH1 mRNA complex. Recently we demonstrated that a Myo4p-She3p-She2p complex does exist in vivo, and this heterotrimeric complex functions to transport ASH1 mRNA to the bud tip. However, our experimental evidence suggests that a molecular reorganization of the heterotrimeric complex is required for ASH1 mRNA to be anchored at the bud tip.
Model for ASH1 mRNA localization. She2p binds ASH1 mRNA and subsequently associates with She3p/Myo4p forming a heterotrimeric complex. The heterotrimeric complex is responsible for transporting the cargo to daughter cells on the polarized actin cytoskeleton. Following transport to the bud tip, molecular reorganization of the transport complex results in the release of She2p and allows anchoring factors (AC) to associate with ASH1 mRNA, She3p and Myo4p. Once anchored ASH1 mRNA is competent for translation in the daughter cell, and newly synthesized Ash1p is imported into the daughter cell nucleus.
It has been shown that the asymmetric segregation of specific mRNA molecules is imperative for normal development of higher eukaryotic organisms. The mechanisms controlling mRNA transport and localization remain elusive. However, many of the mechanisms controlling other aspects of gene expression such as transcription, translation and splicing, are highly conserved from yeast to man. Consequently, we expect that the mechanisms regulating mRNA localization will also be conserved from yeast to higher eukaryotes. With the power of yeast genetics, we are poised to make significant progress in dissecting the mechanisms controlling mRNA localization.
Recent Publications
Urbinati CR, Gonsalvez GB, Aris JP, Long RM. Loc1p is required for efficient assembly and nuclear export of the 60S ribosomal subunit. Mol Genet Genomics. 2006 Oct;276(4):369-77. Epub 2006 Jul 27.
Abstract
Gallas MR, Dienhart MK, Stuart RA, Long RM. Characterization of Mmp37p, a Saccharomyces cerevisiae Mitochondrial Matrix Protein with a Role in Mitochondrial Protein Import. Mol Biol Cell. 2006 Sep;17(9):4051-62. Epub 2006 Jun 21.
Abstract
Gonsalvez GB, Urbinati CR, Long RM. RNA localization in yeast moving towards a mechanism. Biology of the Cell. 2005 Jan 1;97(1):75-86.
Abstract
Gonsalvez GB, Little JL, Long RM. ASH1 mRNA anchoring requires reorganization of the Myo4p-She3p-She2p transport complex. J Biol Chem. 2004 Oct 29;279(44):46286-94. Epub 2004 Aug 23.
Abstract
Gonsalvez GB, Lehmann KA, Ho DK, Stanitsa ES, Williamson JR, Long RM. RNA-protein interactions promote asymmetric sorting of the ASH1 mRNA ribonucleoprotein complex. RNA. 2003 Nov;9(11):1383-99.
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Supplemental Materials
Long RM, McNally MT. mRNA decay: x (XRN1) marks the spot. Mol Cell. 2003 May;11(5):1126-8. Review.
Abstract
Chartrand P, Singer RH, Long RM. RNP localization and transport in yeast. Annu Rev Cell Dev Biol. 2001;17:297-310. Review.
Abstract
Long RM, Gu W, Meng X, Gonsalvez G, Singer RH, Chartrand P. An exclusively nuclear RNA-binding protein affects asymmetric localization of ASH1 mRNA and Ash1p in yeast. J Cell Biol. 2001 Apr 16;153(2):307-18.
Abstract
Long RM, Gu W, Lorimer E, Singer RH, Chartrand P. She2p is a novel RNA-binding protein that recruits the Myo4p-She3p complex to ASH1 mRNA. EMBO J. 2000 Dec 1;19(23):6592-601.
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Chartrand P, Bertrand E, Singer RH, Long RM. Sensitive and high-resolution detection of RNA in situ. Methods Enzymol. 2000;318:493-506.
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Chartrand P, Meng XH, Singer RH, Long RM. Structural elements required for the localization of ASH1 mRNA and of a green fluorescent protein reporter particle in vivo. Curr Biol. 1999 Mar 25;9(6):333-6.
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Contact Information
Email: rlong@mcw.edu
Phone: 414-456-8423
Room: BSB-252