Tag Archives: mitosis

Congratulations to Yansong Miao on his new paper!

Yansong Miao‘s new paper is out now at The Proceedings of the National Academy of Sciences.  Congratulations to Yansong on his great work!  The abstract is below.  The PDF can be downloaded from PNAS here.

Cell-cycle regulation of formin-mediated actin cable assembly. Miao Y, Wong CC, Mennella V, Michelot A, Agard DA, Holt LJ, Yates JR 3rd, Drubin DG. Proc Natl Acad Sci U S A. 2013 Nov 19;110(47):E4446-E4455. Epub 2013 Oct 16.  PMID: 24133141

Abstract

Assembly of appropriately oriented actin cables nucleated by formin proteins is necessary for many biological processes in diverse eukaryotes. However, compared with knowledge of how nucleation of dendritic actin filament arrays by the actin-related protein-2/3 complex is regulated, the in vivo regulatory mechanisms for actin cable formation are less clear. To gain insights into mechanisms for regulating actin cable assembly, we reconstituted the assembly process in vitro by introducing microspheres functionalized with the C terminus of the budding yeast formin Bni1 into extracts prepared from yeast cells at different cell-cycle stages. EM studies showed that unbranched actin filament bundles were reconstituted successfully in the yeast extracts. Only extracts enriched in the mitotic cyclin Clb2 were competent for actin cable assembly, and cyclin-dependent kinase 1 activity was indispensible. Cyclin-dependent kinase 1 activity also was found to regulate cable assembly in vivo. Here we present evidence that formin cell-cycle regulation is conserved in vertebrates. The use of the cable-reconstitution system to test roles for the key actin-binding proteins tropomyosin, capping protein, and cofilin provided important insights into assembly regulation. Furthermore, using mass spectrometry, we identified components of the actin cables formed in yeast extracts, providing the basis for comprehensive understanding of cable assembly and regulation.

Miao 2013 PNAS Figure 2

Average intensity projections along the z-axis of WT cells stained with Alexa-568 phalloidin to label actin filaments and expressing GFP-Tub1 as a cell-cycle stage indicator, obtained using 3D SIM microscopy.

Microtubules and Mitosis Journal Club on Monday, August 26

For Microtubules and Mitosis Journal Club on August 26, members of the Drubin/Barnes Lab, Eva Nogales Lab, and Ahmet Yildiz Lab will discuss the following paper, selected by Itziar Ibarlucea:

Marking and Measuring Single Microtubules by PRC1 and Kinesin-4. Subramanian R, Ti SC, Tan L, Darst SA, Kapoor TM. Cell. 2013 Jul 18;154(2):377-90. PMID: 23870126.

Subramanian Cell 2013

graphical abstract of the paper

Journal Club on Monday, August 6

For Journal Club on August 6, Nate Krefman presented the following paper:

Centromere-like regions in the budding yeast genome. Lefrançois P, Auerbach RK, Yellman CM, Roeder GS, Snyder M. PLoS Genet. 2013;9(1):e1003209. PMID: 23349633.

Lefrancois PLoS Genetics 2013

CLRs confer centromere function on plasmids and chromosomes.

Microtubules and Mitosis Journal Club on Monday, June 24

For Microtubules and Mitosis Journal Club on April 25, members of the Drubin/Barnes Lab, Eva Nogales Lab, and Ahmet Yildiz Lab will discuss the following paper, selected by Stu Howes:

Synergy between XMAP215 and EB1 increases microtubule growth rates to physiological levels. Zanic M, Widlund PO, Hyman AA, Howard J. Nat Cell Biol. 2013 Jun;15(6):688-93. PMID: 23666085.

Zanic NCB 2013

Reaction scheme for an enzymatic reaction with two non-essential activators. The microtubule end is viewed as an enzyme that catalyses the reaction: tubulin in solution (substrate)→tubulin in the polymer (product) by providing a much more efficient pathway than direct incorporation into the lattice. XMAP215 and EB1 are viewed as two non-essential enzyme activators that accelerate the net rate of addition at the end. Filled arrows represent the flux of polymerization through a particular vertex. M, microtubule end; T, free tubulin; X, XMAP215; E, EB1.

Microtubules and Mitosis Journal Club on Thursday, May 23

For Microtubules and Mitosis Journal Club on April 25, members of the Drubin/Barnes Lab, Eva Nogales Lab, and Ahmet Yildiz Lab discussed the following paper, selected by Anthony Cormier:

Tension sensing by Aurora B kinase is independent of survivin-based centromere localization. Campbell CS, Desai A. Nature. 2013 May 2;497(7447):118-21. PMID: 23604256.

Campbell Nature 2013

Model for mechanism of chromosome biorientation.

Microtubules and Mitosis Journal Club on Thursday, April 25

For our new Microtubules and Mitosis Journal Club on April 25, members of the Drubin/Barnes Lab, Eva Nogales Lab, and Ahmet Yildiz Lab discussed the following paper, selected by Nate Krefman:

Estimating the microtubule GTP cap size in vivo. Seetapun D, Castle BT, McIntyre AJ, Tran PT, Odde DJ. Curr Biol. 2012 Sep 25;22(18):1681-7. PMID: 22902755

Example EB1 comet from an EB1-EGFP LLCPK1 cell and the corresponding fluorescence intensity (FI) linescan, blue line.

The Drubin/Barnes Lab Has a New Theme Song!

We now present to you a brand new theme song to introduce the world to all of the awesome people in the Drubin/Barnes Lab!

The Drubin-Barnes Lab!
(Parody of The Brady Bunch Theme Song)

Submission for UC-Berkeley MCB Follies 2012-2013
(UC-Berkeley, Dept. of Molecular and Cell Biology)

LYRICS, VOCALS, CAMERA, EDITING:  Nathaniel Krefman

ADDITIONAL VOCALS:  Akemi Kunibe

STARRING:  The Drubin/Barnes Lab at UC-Berkeley (Fall 2012)!

PIs:  Profs. David Drubin and Georjana Barnes

1st GROUP (microtubules, spindles, kinetochores, & mitosis in budding yeast):  Adrianne Pigula (top left), Nathaniel Krefman (center left), Itziar Ibarlucea-Benitez (bottom left), Prof. Georjana Barnes (center), Anthony Cormier (center right)

2nd GROUP (actin cytoskeleton and endocytosis in mammalian cells and budding yeast):  Aaron Cheng (top left square, left), Jasper Weinberg (top left square, right), Rebecca Lu (center left square, left), Lillie Cohn (center left square, center), Akemi Kunibe (center left square, right), Yansong Miao (bottom left square), Prof. David Drubin (center square), Sun Hae Hong (top right square, left), Yidi Sun (top right square, right), Alex Grassart (center right square, left), Daphne Dambournet (center right square, right), Christa Cortesio (bottom right square, left), Eric Lewellyn (bottom right square, right).

________________________________________________

LYRICS:

Here’s the story of a lovely lady.
Who studied what a microtubule’s for.
All her group loves mitosis, like Georjana,
And kinetochores.

Here’s the story of a PI named David,
Who was interested in actin in live cells,
And his group mapped endocytosis dynamics,
Yet they were by themselves.

After their post-docs, where the lady met this fellow,
And named a protein complex DAM instead of DARN,
They knew their groups must form one laboratory.
That’s the way our lab became the Drubin/Barnes!
The Drubin/Barnes!

That’s the way our lab became the Drubin/Barnes!

Journal Club on Thursday, July 26

For our next Journal Club, our summer undergraduate researcher Josh Johnson will present the following paper:

Aurora B dynamics at centromeres create a diffusion-based phosphorylation gradient.  Wang E, Ballister ER, Lampson MA.  J Cell Biol. 2011 Aug 22;194(4):539-49.  PMID: 21844210.

Journal Club on Monday, July 09

For our next Journal Club, Adrianne Pigula will present the following paper:

A link between mitotic entry and membrane growth suggests a novel model for cell size control.  Anastasia SD, Nguyen DL, Thai V, Meloy M, MacDonough T, Kellogg DR.  J Cell Biol. 2012 Apr 2;197(1):89-104. Epub 2012 Mar 26.  PMID: 22451696.