Marta Miączyńska, PhD, Professor
Laboratory of Cell Biology
International Institute of Molecular and Cell Biology
4 Ks. Trojdena Street, 02-109 Warsaw, Poland
tel: +48 (22) 597 0725; fax: +48 (22) 597 0715
2013 Professor of Biological Sciences, nomination by the President of the Republic of Poland
2008 DSc Habil in Cell Biology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
1997 PhD in Genetics, University of Vienna, Austria
1993 MSc in Molecular Biology, Jagiellonian University, Cracow, Poland
1991 BSc in Biological Sciences, University of Wolverhampton, UK
2001-2005 Senior Postdoctoral Fellow, Max Planck Institute for Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany
1997-2000 Postdoctoral training, European Molecular Biology Laboratory, Heidelberg, Germany
1993-1996 PhD studies, Institute of Microbiology and Genetics, University of Vienna, Austria
1990-1991 Exchange Student, University of Wolverhampton, UK
Fellowships and awards:
2007 Habilitation Fellowship of L’Oreal Poland for Women in Science
2005 International Research Scholar, Howard Hughes Medical Institute, USA (2006-2010)
2005 International Senior Research Fellowship,Wellcome Trust, UK (2006-2011)
2005 Partner Group grant, Max Planck Society,Germany (2006-2010)
2001-2004 Postdoctoral Fellowship, Max Planck Society,Germany
1999-2000 Long Term Postdoctoral Fellowship, Human Frontier Science Program Organization (HFSPO)
1998-1999 Erwin Schrödinger Postdoctoral Fellowship, Austrian Science Fund (FWF)
1993-1996 Bertha von Suttner PhD Scholarship, Austrian Ministry of Science
1990-1991 Studentship, European Community Tempus Scheme
Description of Current Research
We study the ways in which intracellular signal transduction and membrane trafficking in endocytosis are integrated at the molecular level. We focus on proteins that have well known roles in endocytosis to investigate their involvement in various signaling pathways and their impact on patterns of gene expression. Initially, our efforts were focused on studying the endosomal and nuclear roles of APPL proteins. In recent years, we broadened our interests to other multifunctional proteins that act in endocytosis and signaling. The specific projects that are developed by our group seek to answer the following questions:
What is the role of endosomal compartments in the trafficking and signaling of growth factors and cytokines?
How does the endocytic trafficking of receptors impinge on the patterns of gene expression in different signaling pathways?
Endocytosis was first viewed simply as a mechanism of signal termination through the downregulation and degradation of surface receptors. However, more recent data indicate that endosomal compartments and their resident proteins play an important role in transmitting intracellular signals by transporting ligand-receptor complexes and affecting their activity inside the cell (Hupalowska and Miaczynska, Traffic, 2012; Miaczynska, Cold Spring Harb Perspect Biol, 2013; Miaczynska and Bar-Sagi, Curr Opin Cell Biol, 2010; Sadowski et al., Exp Cell Res, 2009). Moreover, several endocytic proteins can undergo nucleocytoplasmic shuttling and interact with nuclear molecules that are involved in transcription or chromatin remodeling, changing their localization or activity, and thus may directly modulate the levels or specificity of gene transcription (Pilecka et al., Eur J Cell Biol, 2007). Importantly, some such dual-function endocytic and nuclear proteins affect cell proliferation or act as tumor suppressors, or their expression changes in human cancers (Pyrzyńska et al., Mol Oncol, 2009).
To systematically study the possible mechanisms by which endocytic proteins may contribute to transcriptional regulation, we recently established and performed small-scale, targeted RNAi screens. We sought to identify the endocytic proteins that affect transcriptional responses in selected signaling pathways, such as those that activate TCF/LEF, AP-1, NF-κB, and STAT transcription factors. All of these pathways can be induced by extracellular ligands that bind appropriate plasma membrane receptors that undergo internalization, but the way in which endocytosis affects the ultimate signaling responses remains poorly investigated and controversial. Luciferase-based reporter tests were used as a primary screening assay to measure transcription that depends on the chosen factors upon knockdown of the genes that encode endocytic proteins. The screens led to the identification of candidate regulators that function as activators or inhibitors of a given pathway. After initial validation, we delineated the molecular mechanisms of action of newly identified regulators. We were using cultured mammalian cells as our main model but have also introduced zebrafish embryos as an additional experimental model in some projects.
In 2015, we completed three projects based on the results of the aforementioned RNAi screens and characterized novel regulators of Wnt, AP-1, and NF-B signaling. In the first of these projects, we characterized an endocytic adaptor protein, Tollip, as a novel, evolutionarily conserved inhibitor of canonical Wnt signaling (Toruń et al., PLoS One, 2015). We found that Tollip depletion potentiated the activity of the β-catenin/TCF-dependent transcriptional reporter, whereas its overproduction inhibited reporter activity and the expression of Wnt target genes. These effects were independent of dynamin-mediated endocytosis but required the ubiquitin-binding CUE domain of Tollip. In Wnt-stimulated cells, Tollip counteracted the activation of β-catenin and its nuclear accumulation, without affecting its total levels. Additionally, under conditions of ligand-independent signaling, Tollip inhibited pathway activity after the stage of β-catenin stabilization. We also demonstrated that the regulation of Wnt signaling by Tollip occurred during early the embryonic development of zebrafish. Our results indicate that the function of Tollip in inhibiting the canonical Wnt pathway may contribute to both embryonic development and carcinogenesis.
In the second project, we identified a link between the GTPase activity of dynamin 2 (Dyn2), a major regulator of endocytic internalization, and the activation of AP-1 transcription factors, composed of Jun and Fos proteins (Szymańska et al., Cell Signal, 2016). We showed that the expression of a dominant-negative Dyn2 K44A mutant strongly stimulated the AP-1 pathway, increasing the total levels of c-Jun, its phosphorylation on Ser63/73, and the transcription of AP-1 target genes. Importantly, DNM2 mutations that are implicated in human neurological disorders exerted similar effects on AP-1 signaling. We further found that Dyn2 K44A induced AP-1 by increasing the phosphorylation of several receptor tyrosine kinases. Their activation was required to initiate a Src- and JNK-dependent signaling cascade that converged on c-Jun and stimulated the expression of AP-1 target genes. Our data uncovered a connection between Dyn2 function and JNK signaling that leads to the induction of AP-1.
In the third project, we identified four components of endosomal sorting complexes required for transport (ESCRTs) as novel inhibitors of NF-κB signaling (Mamińska et al., Sci Signal, 2016). We found that the depletion of Tsg101, Vps28, UBAP1, and CHMP4B in the absence of cytokine stimulation potently activated both canonical and noncanonical NF-κB signaling. This led to upregulation of the expression of NF-κB target genes in cultured human cells, zebrafish embryos, and fat bodies in flies. These effects depended on cytokine receptors, such as the lymphotoxin β receptor (LTβR) and tumor necrosis factor receptor 1 (TNFR1). Upon the depletion of ESCRT subunits, both receptors became concentrated on and signaled from endosomes. The endosomal accumulation of LTβR induced its ligand-independent oligomerization and signaling through TRAF2 and TRAF3 adaptor proteins. We propose that ESCRTs constitutively control the distribution of cytokine receptors in their ligand-free state to restrict their signaling (Fig. 1). This may represent a general mechanism to prevent the spurious activation of NF-κB and uncontrolled inflammatory signaling.
Fig. 1. Model of ESCRT function in restricting NF-κB signaling. (A) Under physiological conditions, cytokine receptors are constitutively internalized, trafficked through endosomes, and degraded in lysosomes. (B) In ESCRT-depleted cells, the transport of cargo toward lysosomes is inhibited. Membrane receptors accumulate in dysfunctional, enlarged endosomes. The local oligomerization and activation of ligand-free cytokine receptors in endosomes induce inflammatory NF-κB signaling. The insets show microscopy images of control (A) and ESCRT-depleted (B) HEK 293 cells. Early endosomes are marked with the EEA1 protein (green channel). The lymphotoxin β receptor (LTβR) is stained in red. Authors: Marta Miączyńska and Agnieszka Mamińska.
Projects conducted in the Laboratory are financed from national and international sources. Among them are two funded by the Foundation for Polish Science:
“Cellular consequences of endosomal dysfunction for proteostasis, metabolism and cancer biology” carried out by Professor Marta Miączyńska within the TEAM programme. Click here for more information
“Role of ESCRT-I protein complex in amino acid and lipid metabolism in the context of erythropoiesis” carried out by Dr. Jarosław Cendrowski within the HOMING programme. Click here for more information
Marta Miączyńska, PhD, Professor
Magdalena Banach-Orłowska, PhD
Ewelina Szymańska, PhD
Daria Zdżalik-Bielecka, PhD
Jarosław Cendrowski, PhD
Kamil Jastrzębski, PhD
Krzysztof Kolmus, PhD
Lidia Wolińska-Nizioł, PhD
Marta Kaczmarek, MSc
Małgorzata Maksymowicz, MSc
Agata Poświata, MSc
Karolina Wojciechowska, MSc
Kamila Kozik, Eng.
Karolina Romaniuk, Eng.
Małgorzata Świątek, Eng.
Michał Mazur, MSc
Blair Stewig, BSc (Fulbright Student Researcher)
Renata Wyszyńska, MSc
Monika Matuszczyk (part-time)
Paulina Nowak, MSc
Paulina Okafor, MSc
Patryk Ślusarczyk, MSc