PD Dr. Tanja Maritzen
phone +49 30 94793 - 214 (office)/ -368 (lab)

Maritzen Lab Research

Endocytic sorting and cell migration

Cell motility is essential for numerous physiological processes ranging from morphogenesis and wound healing to innate and adaptive immunity. Its dysregulation is involved in diseases such as cancer and autoimmune syndromes. Cell migration relies crucially on coordinated membrane transport. Adhesion turnover and the response to extracellular signals such as chemokines have to be tightly controlled by the endocytosis and recycling of cell surface adhesion proteins and chemokine receptors as well as other receptors controling signaling cascades that modulate migration.

With Stonin1 we have recently characterized an endocytic adaptor protein that affects cellular motility by regulating the surface level of a crucial proteoglycan (Feutlinske, Nat Commun, 2015). Stonin1 is found at a specific subset of peripheral clathrin-coated pits in the vicinity of focal adhesions which suggested a role in focal adhesion dynamics. In line with this, we found focal adhesion disassembly to be slowed down in Stonin1 deficient mouse embryonic fibroblasts (MEFs). Consistent with the notion that focal adhesion dynamics are intimately linked to cellular motility, Stonin1 KO MEFs move with higher directional persistence in random migration assays. We could show that the altered migratory behaviour of the Stonin 1 KO cells is due to the accumulation of the proteoglycan NG2 whose internalization is impaired in absence of its endocytic adaptor Stonin1. NG2 acts as co-receptor for integrins and PDGFR (platelet derived growth factor receptor) and is known to influence cellular motility and tumor growth. Its accumulation in Stonin1 KO cells leads to increased PDGFR activation and downstream signaling.

Our work illustrates how endocytic regulation fine-tunes cellular signaling and motility. As dysregulation of these processes is a hallmark of cancer and in light of the established function of NG2 as oncogene, Stonin1 might act as tumor suppressor by limiting NG2´s oncogenic potential via its removal from the plasma membrane, a hypothesis that we are currently testing.


Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP)
Campus Berlin-Buch
Robert-Roessle-Str. 10
13125 Berlin, Germany
+4930 94793 - 100 
+4930 94793 - 109 (Fax)

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