I am a passionate cellular and molecular biologist with expertise in research related to cancer, genomic/chromosomal instability, DNA damage response, epigenetics, cellular identity (transdifferentiation, induced neurons), and proteomics (interactions, biomarkers). My extensive practical experience is reflected by 10 publications that score a total impact factor of >45. I possess excellent communication and technical writing skills (English/German), as evidenced by over $460,000 won from scholarships, grants & awards. Recent highlight: Postdoctoral Young Investigator Award from Stanford University for scientific merit, commitment & leadership.
Honors & Awards
BSc Scholarship for Academic Achievement, University of Salzburg, Austria
MSc awarded with highest distinction, University of Salzburg, Austria
Achievers in Medical Science Graduate Recruitment Scholarship, Anonymous Donor via the University of Calgary, Canada
Faculty of Graduate Studies PhD Scholarship, University of Calgary, Canada
Travel Award for Scientific Symposium: DNA Damage-From Causes to Cures, The Biochemical Society, London, UK
DOC-PhD Scholarship, Austrian Academy of Sciences, Vienna, Austria
4x Achievers in Medical Science Research Excellence Award, Anonymous Donor via the University of Calgary, Canada
Travel Award for Gordon Research Conference: Mammalian DNA repair, Gordon Research Conferences, Ventura, USA
Award for best poster at the 2009 HBI Conference, Hotchkiss Brain Institute, University of Calgary, Canada
2x Graduate Student Award, Department of Biochemistry and Molecular Biology, University of Calgary, Canada
Award for best poster at the 2010 BMB Departmental Retreat, Department of Biochemistry and Molecular Biology, University of Calgary, Canada
ACF Graduate Studentship, Alberta Cancer Foundation, Calgary/Edmonton, Canada
Boards, Advisory Committees, Professional Organizations
Member, ASCINA-Austrian scientists in North America (2014 - Present)
Bachelor of Science, Universitat Salzburg (2004)
Magister, Universitat Salzburg (2006)
Doctor of Philosophy, University of Calgary (2013)
Marius Wernig, Postdoctoral Faculty Sponsor
Current Research and Scholarly Interests
My MSc project, carried out at the University of Salzburg in cooperation with the biotechnology company ProComCure, investigated the molecular interface between human cells and the bacterium Staphylococcus aureus. S. aureus exhibits a dramatic increase in resistance to antibiotics, thereby causing enormous challenges for health care. Using proteomics platforms, I identified numerous novel host-pathogen interactions. These findings are being developed further by ProComCure in order to design innovative therapies for S. aureus infections.
My dissertation project, carried out at the University of Calgary, defined the functions of the human protein TPX2. TPX2 has been discovered over 17 years ago for its unique property to mediate cell division. However, when not involved in cell division TPX2 resides in the cell nucleus where its role had remained unknown. Building on my background in proteomics, I discovered a novel TPX2-containing protein complex that resides in the nucleus. Analysis of this complex unraveled a completely unexpected role for TPX2 in cellular reactions triggered by insults to DNA. To avoid cancers, cells respond to damaged DNA by either attempting its repair or, if this is not possible, by committing 'suicide'. My findings established that TPX2 impacts the molecular mechanisms that underlie these responses to DNA damage. More specifically, I found that TPX2 accumulates at DNA lesions and that the cellular levels of TPX2 negatively correlate with the ‘strength’ of the DNA damage response. Thus, TPX2 affects cellular proliferation, DNA repair, and survival upon genomic insult. This was the first function discovered for TPX2 in the cell nucleus. Since abnormally high levels of TPX2 are often found in human cancers, my discovery sheds light on the mechanistic implication of this protein in carcinogenesis. Furthermore, TPX2 is also a promising therapeutic target and my findings may advance novel cancer therapies. We propose that future treatments may attempt to reduce TPX2 levels in order to increase the strength of the DNA damage response. Subsequently, chemo- and radiotherapy doses may be lowered but still stay effective.
In 2014, I joined the Wernig laboratory at Stanford University. Here, I capitalize on my expertise in mechanisms of DNA damage response to develop a pioneering technique capable of repairing pathogenic mutations in the genetic material of patients suffering from Epidermolysis Bullosa (a devastating and often lethal disease that causes chronic erosion of the skin). This novel technique, called CRISPR, introduces experimentally controlled and transient damage to the mutated DNA of patient cells and exploits naturally occurring DNA repair mechanisms to transform the disease-causing mutation to a normal state. I will combine development of CRISPR with Dr. Wernig’s expertise in regenerative medicine to generate patient derived stem cells with repaired (i.e. normal) genes. Subsequently, these stem cells will be employed to regenerate the skin of Epidermolysis Bullosa patients.
Revealing the protein interface between Staphylococcus aureus and Human, University of Salzburg
Defining a role for TPX2 in the nucleus: Regulation of the DNA damage response, University of Calgary
Epigenetic-based mechanisms of DNA damage response, University of Calgary
Investigating the function of the SIRT1 deacetylase, University of Calgary
Phosphorylation of Targeting Protein for Xenopus Kinesin-like Protein 2 (TPX2) at Threonine 72 in Spindle Assembly
JOURNAL OF BIOLOGICAL CHEMISTRY
2015; 290 (14): 9122-9134
The human ortholog of the targeting protein for Xenopus kinesin-like protein 2 (TPX2) is a cytoskeletal protein that plays a major role in spindle assembly and is required for mitosis. During spindle morphogenesis, TPX2 cooperates with Aurora A kinase and Eg5 kinesin to regulate microtubule organization. TPX2 displays over 40 putative phosphorylation sites identified from various high-throughput proteomic screenings. In this study, we characterize the phosphorylation of threonine 72 (Thr(72)) in human TPX2, a residue highly conserved across species. We find that Cdk1/2 phosphorylate TPX2 in vitro and in vivo. Using homemade antibodies specific for TPX2 phosphorylated at Thr(72), we show that this phosphorylation is cell cycle-dependent and peaks at M phase. Endogenous TPX2 phosphorylated at Thr(72) does not associate with the mitotic spindle. Furthermore, ectopic GFP-TPX2 T72A preferentially concentrates on the spindle, whereas GFP-TPX2 WT distributes to both spindle and cytosol. The T72A mutant also increases the proportion of cells with multipolar spindles phenotype. This effect is associated with increased Aurora A activity and abnormally elongated spindles, indicative of higher Eg5 activity. In summary, we propose that phosphorylation of Thr(72) regulates TPX2 localization and impacts spindle assembly via Aurora A and Eg5.
View details for DOI 10.1074/jbc.M114.591545
View details for Web of Science ID 000352207100035
View details for PubMedID 25688093
View details for PubMedCentralID PMC4423697
TPX2 Impacts Acetylation of Histone H4 at Lysine 16: Implications for DNA Damage Response
2014; 9 (11)
During interphase, the spindle assembly factor TPX2 is compartmentalized in the nucleus where its roles remain largely uncharacterized. Recently, we found that TPX2 regulates the levels of serine 139-phosphoryated H2AX (γ-H2AX) at chromosomal breaks induced by ionizing radiation. Here, we report that TPX2 readily associates with the chromatin in the absence of ionizing radiation. Overexpression of TPX2 alters the DAPI staining pattern of interphase cells and depletion of TPX2 constitutively decreases the levels of histone H4 acetylated at lysine16 (H4K16ac) during G1-phase. Upon ionizing irradiation, this constitutive TPX2 depletion-dependent decrease in H4K16ac levels correlates with increased levels of γ-H2AX. The inversely correlated levels of H4K16ac and γ-H2AX can also be modified by altering the levels of SIRT1, herein identified as a novel protein complex partner of TPX2. Furthermore, we find that TPX2 depletion also interferes with formation of 53BP1 ionizing radiation-induced foci, known to depend on γ-H2AX and the acetylation status of H4K16. In brief, our study is the first indication of a constitutive control of TPX2 on H4K16ac levels, with potential implications for DNA damage response.
View details for DOI 10.1371/journal.pone.0110994
View details for Web of Science ID 000345558100041
View details for PubMedID 25365214
View details for PubMedCentralID PMC4217740
TPX2: of spindle assembly, DNA damage response, and cancer
CELLULAR AND MOLECULAR LIFE SCIENCES
2014; 71 (16): 3027-3047
For more than 15 years, TPX2 has been studied as a factor critical for mitosis and spindle assembly. These functions of TPX2 are attributed to its Ran-regulated microtubule-associated protein properties and to its control of the Aurora A kinase. Overexpressed in cancers, TPX2 is being established as marker for the diagnosis and prognosis of malignancies. During interphase, TPX2 resides preferentially in the nucleus where its function had remained elusive until recently. The latest finding that TPX2 plays a role in amplification of the DNA damage response, combined with the characterization of TPX2 knockout mice, open new perspectives to understand the biology of this protein. This review provides an historic overview of the discovery of TPX2 and summarizes its cytoskeletal and signaling roles with relevance to cancer therapies. Finally, the review aims to reconcile discrepancies between the experimental and pathological effects of TPX2 overexpression and advances new roles for compartmentalized TPX2.
View details for DOI 10.1007/s00018-014-1582-7
View details for Web of Science ID 000339718900003
View details for PubMedID 24556998
p600 regulates spindle orientation in apical neural progenitors and contributes to neurogenesis in the developing neocortex
2014; 3 (6): 475-485
Apical neural progenitors (aNPs) drive neurogenesis by means of a program consisting of self-proliferative and neurogenic divisions. The balance between these two manners of division sustains the pool of apical progenitors into late neurogenesis, thereby ensuring their availability to populate the brain with terminal cell types. Using knockout and in utero electroporation mouse models, we report a key role for the microtubule-associated protein 600 (p600) in the regulation of spindle orientation in aNPs, a cellular event that has been associated with cell fate and neurogenesis. We find that p600 interacts directly with the neurogenic protein Ndel1 and that aNPs knockout for p600, depleted of p600 by shRNA or expressing a Ndel1-binding p600 fragment all display randomized spindle orientation. Depletion of p600 by shRNA or expression of the Ndel1-binding p600 fragment also results in a decreased number of Pax6-positive aNPs and an increased number of Tbr2-positive basal progenitors destined to become neurons. These Pax6-positive aNPs display a tilted mitotic spindle. In mice wherein p600 is ablated in progenitors, the production of neurons is significantly impaired and this defect is associated with microcephaly. We propose a working model in which p600 controls spindle orientation in aNPs and discuss its implication for neurogenesis.
View details for DOI 10.1242/bio.20147807
View details for Web of Science ID 000348069200007
View details for PubMedID 24812355
A Ca2+-dependent Mechanism of Neuronal Survival Mediated by the Microtubule-associated Protein p600
JOURNAL OF BIOLOGICAL CHEMISTRY
2013; 288 (34): 24452-24464
In acute and chronic neurodegeneration, Ca(2+) mishandling and disruption of the cytoskeleton compromise neuronal integrity, yet abnormalities in the signaling roles of cytoskeletal proteins remain largely unexplored. We now report that the microtubule-associated protein p600 (also known as UBR4) promotes neuronal survival. Following depletion of p600, glutamate-induced Ca(2+) influx through NMDA receptors, but not AMPA receptors, initiates a degenerative process characterized by endoplasmic reticulum fragmentation and endoplasmic reticulum Ca(2+) release via inositol 1,4,5-trisphosphate receptors. Downstream of NMDA receptors, p600 associates with the calmodulin·calmodulin-dependent protein kinase IIα complex. A direct and atypical p600/calmodulin interaction is required for neuronal survival. Thus, p600 counteracts specific Ca(2+)-induced death pathways through regulation of Ca(2+) homeostasis and signaling.
View details for DOI 10.1074/jbc.M113.483107
View details for Web of Science ID 000330612300015
View details for PubMedID 23861403
View details for PubMedCentralID PMC3750145
Targeting protein for xenopus kinesin-like protein 2 (TPX2) regulates ?-histone 2AX (?-H2AX) levels upon ionizing radiation.
journal of biological chemistry
2012; 287 (50): 42206-42222
The microtubule-associated protein targeting protein for Xenopus kinesin-like protein 2 (TPX2) plays a key role in spindle assembly and is required for mitosis in human cells. In interphase, TPX2 is actively imported into the nucleus to prevent its premature activity in microtubule organization. To date, no function has been assigned to nuclear TPX2. We now report that TPX2 plays a role in the cellular response to DNA double strand breaks induced by ionizing radiation. Loss of TPX2 leads to inordinately strong and transient accumulation of ionizing radiation-dependent Ser-139-phosphorylated Histone 2AX (γ-H2AX) at G(0) and G(1) phases of the cell cycle. This is accompanied by the formation of increased numbers of high intensity γ-H2AX ionizing radiation-induced foci. Conversely, cells overexpressing TPX2 have reduced levels of γ-H2AX after ionizing radiation. Consistent with a role for TPX2 in the DNA damage response, we found that the protein accumulates at DNA double strand breaks and associates with the mediator of DNA damage checkpoint 1 (MDC1) and the ataxia telangiectasia mutated (ATM) kinase, both key regulators of γ-H2AX amplification. Pharmacologic inhibition or depletion of ATM or MDC1, but not of DNA-dependent protein kinase (DNA-PK), antagonizes the γ-H2AX phenotype caused by TPX2 depletion. Importantly, the regulation of γ-H2AX signals by TPX2 is not associated with apoptosis or the mitotic functions of TPX2. In sum, our study identifies a novel and the first nuclear function for TPX2 in the cellular responses to DNA damage.
View details for DOI 10.1074/jbc.M112.385674
View details for PubMedID 23045526
View details for PubMedCentralID PMC3516765
- Targeting Protein for Xenopus Kinesin-like Protein 2 (TPX2) Regulates gamma-Histone 2AX (gamma-H2AX) Levels upon Ionizing Radiation JOURNAL OF BIOLOGICAL CHEMISTRY 2012; 287 (50): 42206-42222
The Cytoskeletal Protein Ndel1 Regulates Dynamin 2 GTPase Activity
2011; 6 (1)
Cytoskeleton dynamics, membranes trafficking and positioning are essential for the proper functioning of any mammalian cell. The identification of the molecules and mechanisms that allow these cellular processes to interface is vital for understanding cell behaviors. Ndel1, the mammalian homolog of the Aspergillus nidulans NudE, organizes the cytoskeleton and regulates molecular motors, thereby impacting on the positioning of membranes. Hypothetically, Ndel1 can act in concert with enzymes controlling membrane trafficking (vesicle-mediated transport) per se, but this idea has never been investigated. We now report that a pool of Ndel1 associates directly with Dynamin 2 (Dyn2), a large cytosolic GTPase involved in the trafficking of the AMPA receptor subunit GluR1. In vitro, Ndel1 enhances Dyn2 GTPase activity in its unassembled and assembled forms, without promoting oligomerization of the enzyme. In cells, gain and loss of function of Ndel1 recapitulate the effects of overexpression of Dyn2 and Dyn2 dominant negative with reduced GTPase activity on the intracellular localization of GluR1, respectively, without affecting the stability of microtubules. Together, these results indicate that Ndel1 regulates Dyn2 GTPase activity and impacts GluR1-containing membranes distribution in a manner reminiscent of Dyn2.
View details for DOI 10.1371/journal.pone.0014583
View details for Web of Science ID 000286661400002
View details for PubMedID 21283621
View details for PubMedCentralID PMC3026782
Ndel1 controls the dynein-mediated transport of vimentin during neurite outgrowth
JOURNAL OF BIOLOGICAL CHEMISTRY
2008; 283 (18): 12232-12240
Ndel1, the mammalian homologue of the Aspergillus nidulans NudE, is emergently viewed as an integrator of the cytoskeleton. By regulating the dynamics of microtubules and assembly of neuronal intermediate filaments (IFs), Ndel1 promotes neurite outgrowth, neuronal migration, and cell integrity (1-6). To further understand the roles of Ndel1 in cytoskeletal dynamics, we performed a tandem affinity purification of Ndel1-interacting proteins. We isolated a novel Ndel1 molecular complex composed of the IF vimentin, the molecular motor dynein, the lissencephaly protein Lis1, and the cis-Golgi-associated protein alphaCOP. Ndel1 promotes the interaction between Lis1, alphaCOP, and the vimentin-dynein complex. The functional result of this complex is activation of dynein-mediated transport of vimentin. A loss of Ndel1 functions by RNA interference fails to incorporate Lis1/alphaCOP in the complex, reduces the transport of vimentin, and culminates in IF accumulations and altered neuritogenesis. Our findings reveal a novel regulatory mechanism of vimentin transport during neurite extension that may have implications in diseases featuring transport/trafficking defects and impaired regeneration.
View details for DOI 10.1074/jbc.M710200200
View details for Web of Science ID 000255340000039
View details for PubMedID 18303022
Ndel1 Promotes Axon Regeneration via Intermediate Filaments
2008; 3 (4)
Failure of axons to regenerate following acute or chronic neuronal injury is attributed to both the inhibitory glial environment and deficient intrinsic ability to re-grow. However, the underlying mechanisms of the latter remain unclear. In this study, we have investigated the role of the mammalian homologue of aspergillus nidulans NudE, Ndel1, emergently viewed as an integrator of the cytoskeleton, in axon regeneration. Ndel1 was synthesized de novo and upregulated in crushed and transected sciatic nerve axons, and, upon injury, was strongly associated with neuronal form of the intermediate filament (IF) Vimentin while dissociating from the mature neuronal IF (Neurofilament) light chain NF-L. Consistent with a role for Ndel1 in the conditioning lesion-induced neurite outgrowth of Dorsal Root Ganglion (DRG) neurons, the long lasting in vivo formation of the neuronal Ndel1/Vimentin complex was associated with robust axon regeneration. Furthermore, local silencing of Ndel1 in transected axons by siRNA severely reduced the extent of regeneration in vivo. Thus, Ndel1 promotes axonal regeneration; activating this endogenous repair mechanism may enhance neuroregeneration during acute and chronic axonal degeneration.
View details for DOI 10.1371/journal.pone.0002014
View details for Web of Science ID 000261558700030
View details for PubMedID 18431495
View details for PubMedCentralID PMC2291557
Protein 600 is a microtubule/endoplasmic reticulum-associated protein in CNS neurons
JOURNAL OF NEUROSCIENCE
2008; 28 (14): 3604-3614
There is an increasing body of literature pointing to cytoskeletal proteins as spatial organizers and interactors of organelles. In this study, we identified protein 600 (p600) as a novel microtubule-associated protein (MAP) developmentally regulated in neurons. p600 exhibits the unique feature to interact with the endoplasmic reticulum (ER). Silencing of p600 by RNA interference (RNAi) destabilizes neuronal processes in young primary neurons undergoing neurite extension and containing scarce staining of the ER marker Bip. Furthermore, in utero electroporation of p600 RNAi alters neuronal migration, a process that depends on synergistic actions of microtubule dynamics and ER functions. p600-depleted migrating neurons display thin, crooked, and "zigzag" leading process with very few ER membranes. Thus, p600 constitutes the only known MAP to associate with the ER in neurons, and this interaction may impact on multiple cellular processes ranging from neuronal development to neuronal maturation and plasticity.
View details for DOI 10.1523/JNEUROSCI.5278-07.2008
View details for Web of Science ID 000254623500010
View details for PubMedID 18385319