BS: Lomonosov Moscow State University
PhD: Russian Academy of Science
Postdoctoral Training: Fox Chase Center

Joined the faculty: 2007

Affiliations: MBR Cancer Center

Teaching: CCMD 793M, CCB 701, CCB 700

Room: 2826 MBRCC
Phone: (304) 293-5295
Fax: (304) 293-4667
Email: epugacheva@hsc.wvu.edu

Project #1

To investigate involvement of adhesion proteins in activation of the AurA mitotic kinase, and the role of mitotic kinases in adhesion signal transduction.

The fundamental question we are interested in is how cell adhesion and cell mitotic machineries communicate with each other. It is the matter of life for a multi-cellular organism, where specific and oriented adhesions were evolutionary necessary to develop. The main focus of the Pugacheva Lab is the focal adhesion scaffolding proteins of the Cas family (p130Cas, HEF1\CasL\Nedd9, Efs\Sin, HEPL). HEF1, a member of this family functions in both cell adhesion and mitosis. The first observation of HEF1 localization in the mitotic spindle dates to 1996 (Low S., Molecular and Cellular Biology, 1996), but the functional significance of this was not clear at that time. Centrosome and microtubules are the key elements of mitotic spindle. Recently, we have identified HEF1 as a centrosomal protein and have shown its role in centrosome maturation and mitosis initiation. Mitotic onset as well as exit from mitosis precisely orchestrated by the mitotic kinases of Aurora, PLK and NIMA families. We found that HEF1 is the direct binding partner and one of the activators of the mitotic kinase Aurora A (Pugacheva et al., Nature Cell Biology, 2005). Aurora A is an evolutionary conserved Ser/Thr kinase. It was found extremely important for licensing mitotic entry in variety of living organisms mainly through phosphorylation of cyclins, histones, kinases and centrosome scaffolding proteins. Inactivation of Aurora A causes cell cycle arrest at G2/M phase and withdraws cells from further division. It is not surprising that AurA was found over expressed in majority of human cancers. Molecular mechanisms of AurA activation are not well defined. Interestingly, another recently published Aurora A activator, the protein of Zyxin family- Ajuba, was found in the complex with p130Cas (Pratt et al., J Cell Biol. 2005). As a part of an ongoing project we study potential interaction between Ajuba and HEF1 proteins and its importance for mitotic regulation. The current model AurA activation in mitosis is depicted on Fig.1.

Fig1. Activation and stability of AurA kinase is tightly regulated during the cell cycle. HEF1 and Ajuba were recently identified as AurA binding partners promoting AurA activity at the G2/M transition.

Project # 2

Determine molecular mechanisms governing cell-cycle dependent cilium disassembly in mammalian cells.

AurA function was closely related to regulation of cell cycle and was studied only in mitosis. Surprisingly, while we were working on Aur-HEF1 connection, we discovered that AurA is important for disassembly of centrosome-based structure called cilia in G1 phase of the cell cycle. Primary cilia can be detected on the apical surface of the cells and are considered as an environment sensory organ implicated in cell migration, Ca2+ dynamics, proliferation and differentiation. A number of human diseases are associated with ciliary dysfunction, including polycystic kidney disease (PKD), male infertility and Bardet-Biedl Syndrome (BBS). Using the immortalized retinal pigment epithelium cell line (RPE1-hTERT), we have identified AurA kinase as a necessary and sufficient factor inducing cilium disassembly (Pugacheva et al Cell 2007). Our current efforts are dedicated to outlining the molecular mechanisms governing AurA activation in G0/G1 phase and finding AurA substrates responsible for cilium disassembly. One of the potential substrates we have identified is HDAC6. HDAC6 directly regulates microtubule dynamics by deacetylation of microtubule bundles. Phosphorylation by AurA causes a substantial increase in HDAC6 deacetylase activity and promotes microtubule instability. As the upstream regulators of AurA activity: HEF1 and PAK1 (p21 activated kinase) were suggested. As an ongoing project we study how inactivation of PAK1 could regulate cilium dynamics in human cells. We think that adhesion scaffolding proteins serve as ideal mechanic sensors regulating the length of cilium at different stages of cell cycle and upon certain environmental changes, like growth factors, Ca2+ release or pH (Fig.2).

Fig.2 Working Model. A. Aurora A (AurA) and low levels of HEF1 are localized to the basal body of quiescent, ciliated cells. B. Growth factors induce HEF1 expression, promoting HEF1-dependent activation of Aurora A. This results in phosphorylation of ciliary HDAC6 6 (H6) by Aurora A, thereby inducing ciliary resorption.

  References:

• Pugacheva, EN, Bluestein SA, Feng Y, Longmore GD, and Golemis EA. “A HEF1-Ajuba protein complex synergistically activates Aurora-A kinase.” (Manuscript in preparation).
   
• Pugacheva, EN and Golemis E.A. “Tissue specific activation of AurA kinase in response to adhesion keys”. (Manuscript in preparation).
   
• Pugacheva, EN, Jablonski SA, HartmanTR, Henske EP and Golemis EA. “HEF1-dependent Aurora A activation induces disassembly of the primary cilium." Cell. 2007 Jun 29;129(7):1351-63 Plotnikova OV, Golemis EA, Pugacheva EN. Cell cycle-dependent ciliogenesis and cancer. Cancer Res. 2008;68(7):2058-61. PM:18381407.
   
• Pugacheva, EN and Golemis E.A. HEF1-Aurora A interactions: points of dialog between the cell cycle and cell attachment signaling networks. Cell Cycle. 2006 Feb 15:5(4).
   
• Dadke D, Jarnik M, Pugacheva EN, Singh MK, Golemis EA..Deregulation of HEF1 Impairs M-Phase Progression by Disrupting the RhoA Activation Cycle. Mol Biol Cell. 2006 Jan 4; [Epub ahead of print].
   
• Pugacheva, EN and Golemis E.A. Building a better web: progress in the concept and methodology of protein interaction studies. pp. 13-35 in Protein-Protein Interactions, Second Edition: a Molecular Cloning Manual, 938 pages. Eds. Golemis, E.A. and Adams, P.D., Cold Spring Harbor Laboratory Press, New York, 2005.