My research focuses on the
dynamic regulation of Protein Phosphatase 1 (PP1) in mammalian
cells by "targeting subunits" that direct its activity
toward particular sites within the cell and particular substrates
at these sites. More than 90 targeting subuntis have been
identified so far, and the ubiquitous role of PP1 in the regulation
of cellular serine/threonine phosphorylation levels indicates
that many more remain to be identified. Part of my work involves
cataloguing these known and novel targeting subunits and identifying
any preferential associations with a particular PP1 isoform
in live cells. This work has been greatly facilitated by the
development of SILAC (Stable Isotope Labeling of Amino acids
in Cell culture)-based quantitative proteomics, and our initial
study of differential PP1 isoform targeting was published
in 2006 (Trinkle-Mulcahy, L., Andersen,
J., Lam, Y.W., Moorhead, G., Mann, M. and Lamond, A.I. Repo-Man
recruits PP1γ to chromatin and is essential for cell
viability. J. Cell Biol. 172:679-92).
I have since extended this work to optimize the
rapid and reliable identification of protein interaction partners
by a combination of affinity purification (tagged or endogenous
proteins), SILAC-based quantitative proteomics and bead proteome
filtering (submitted). For more information
see our SILAC IP page and SILAC
FAQ page. Details are also on our
Proteomics page.
The use of GFP-tagged PP1 isoforms has enabled me to study
localization and regulation of the phosphatase in living cells,
both throughout the cell cycle and following various cellular
perturbations. For more information about working with fluorescent
PP1 (establishing stable cell lines, photobleaching experiments,
FRET, etc.), check out our chapter on "Visualization
of intracellular PP1 targeting through transiently and stably
expressed fluorescent protein fusions" in the Methods
in Molecular Biology book entitled Protein Phosphatase Protocols
(edited by Greg Moorhead).
For more general information about the role of protein phosphatases
in the cell nucleus and during cell division, check out the
following reviews:
Moorhead, G.B.G., Trinkle-Mulcahy, L.
and Ulke-Lemee, A. Emerging roles of nuclear protein
phosphatases. Nat. Rev. Mol. Cell Biol. 3:234-44, 2007.
Trinkle-Mulcahy, L. and Lamond, A.I. Mitotic phosphatases:
no longer silent partners. Current Opinion in Cell Biology.
18:623-31, 2006.
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Moving was stressful, but my new (literally) lab was
waiting for me. Now I just need to fill it! For more information
about the Department
of Cellular and Molecular Medicine here at the University
of Ottawa, follow the links. |
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Angus and I have written a minireview for a special
cell nucleus-themed edition of FEBS Letters. The article
is entitled "Nuclear Functions in Space and Time:
Gene expression in a dynamic, constrained environment". |
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As part of a special Science issue highlighting
the nucleus, Angus and I wrote a review article entitled
"Toward
a High Resolution View of Nuclear Dynamics,"
. In it we discuss how recent advances in live cell
imaging and proteomics are driving nuclear research
forward. |
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I've been working in collaboration with the artist
Paul Harrison at the University of Dundee Visual Arts
Centre, as part of the "Designs for Life"
sci-art project. You can check out the website here:
Designs
for Life |
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Sam Swift (University of Dundee Light Microscope Facility
Manager) and I have written another article in our series
on general micrsocopy issues for the Royal Microscopy
Society's InFocus magazine. This one focuses on the measurement
of localization, colocalization and direct interaction
of proteins within the cell. |
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