Research Projects (Third party funds)
Pathogen-host communication and target identification for the development of novel anti-infectives
Type III secreted virulence factors are a typical asset of gram-negative pathogens that are a notorious problem. In many cases, it has been shown that single virulence factors can be decisive for virulence. However, for all of them, deletion of the T3SS would largely abrogate virulence. Therefore, targeting of crucial virulence factor activities or the T3SS itself is a prototypic example for a so-called pathoblocker strategy. A prime target of these T3-secreted factors is the actin cytoskeleton, either directly or indirectly by manipulating Rho-GTPase signalling. For our research, we thus specifically selected these factors and pathways because they represent druggable targets. In fact, small molecule inhibitors for host Rho GTPases are already available, which are all in the focus for anti-cancer drug development (Shang X, Marchioni F, Sipes N, et al. (2012) Rational design of small molecule inhibitors targeting RhoA subfamily Rho GTPases. Chemistry & biology. 19(6):699-710. doi:10.1016/j.chembiol.2012.05.009). We are currently testing their effectivity in preventing pathogen invasion.
A) Rho-GTPases in general and Rho, the main mediator of contractility in particular, are prime targets of bacterial virulence factors. With the aim to gain a deeper understanding of the cellular functions of these GTPases and in order to be able to challenge their individual roles for infection, Rho-GTPase knockouts of RhoA, -B and –C are being established using the CRISPR/Cas9 method. In addition, other actin regulators involved in the process of host pathogen interactions are currently being targeted, such as cortactin.
B) SopB is the leading virulence factor of Salmonella for Rho-mediated invasion. Thus, we have studied the role of the Shigella otholog of SopB, namely IpgD. To understand if the function of IpgD is conserved between these two pathogens and furthermore, if this is conserved among other Gram-negative bacteria harbouring SopB-orthologs, we utilized isogenic complementation experiments with 10 of these factors. Strikingly, despite varying reports on their individual roles, their function is conserved and they apparently embody a solid indicator for an intracellular live style, no matter whether in pathogenic or symbiotic context.
Relevant publications concerning this project:
I. Schnoor M, Stradal TE, Rottner K (2017) Cortactin: Cell Functions of A Multifaceted Actin-Binding Protein. Trends Cell Biol doi: 10.1016/j.tcb.2017.10.009.
II. Steffen A, Stradal TE, Rottner K (2017) Signalling Pathways Controlling Cellular Actin Organization. Handb Exp Pharmacol 235: 153-78.
III. Stradal TE, Costa SC (2017) Type III Secreted Virulence Factors Manipulating Signaling to Actin Dynamics. Curr Top Microbiol Immunol 399: 175-99.
IV. Hänisch, J., Stradal, T.E., Rottner, K (2012) A novel contractility pathway operating in Salmonella invasion. Virulence 3(1), 81-86
V. de Groot, J.C., Schlüter, K., Carius, Y., Quedenau, C., Vingadassalom, D., Faix, J., Weiss, S.M., Reichelt, J., Standfuß-Gabisch, C., Lesser, C.F., Leong, J.M., Heinz, D.W., Büssow, K., Stradal, T.E. (2011) Structural basis for complex formation between human IRSp53 and the translocated intemin receptor Tir of enterohemorrhagic E. coli. Structure 19(9), 1294-1306.
VI. Hänisch, J., Kölm, R., Wozniczka, M., Bumann, D. Rottner, K, Stradal, T.E. (2011) Activation of a RhoA/myosin II-dependent but Arp2/3 complex-independent pathway facilitates Salmonella invasion. Cell Host & Microbe 9(4), 273-285.
VII. Hänisch, J., Ehinger, J., Ladwein, M., Rohde, M., Bosse, T., Steffen, A., Bumann, D., Misselwitz, B., Freihofer, P., Hardt, W.D., Stradal, T.E., Rottner, K. (2010) Molecular dissection of Salmonella-induced membrane ruffling versus invasion. Cell. Microbio. 12(1), 84-98.
VIII. Böttcher RT, Veelders M, Rombaut P, Faix J, Theodosiou M, Stradal TE, Rottner K, Zent R, Herzog F, Fässler R Kindlin-2 recruits paxillin and Arp2/3 to promote membrane protrusions during initial cell spreading. J Cell Biol 216(11): 3785-98.
IX. Noumeur SR, Helaly SE, Jansen R, Gereke M, Stradal TEB, Harzallah D, Stadler M (2017) Preussilides A-F, Bicyclic Polyketides from the Endophytic Fungus Preussia similis with Antiproliferative Activity. J Nat Prod 80(5): 1531-40.
X. Kage F, Steffen A, Ellinger A, Ranftler C, Gehre C, Brakebusch C, Pavelka M, Stradal T, Rottner K (2017) FMNL2 and -3 regulate Golgi architecture and anterograde transport downstream of Cdc42. Sci Rep 7(1): 9791.
XI. Weiss SM, Ladwein M, Schmidt D, Ehinger J, Lommel S, Städing K, Beutling U, Disanza A, Frank R, Jänsch L, Scita G, Gunzer F, Rottner K, Stradal TE (2009) IRSp53 links the enterohemorrhagic E. coli effectors Tir and EspFU for actin pedestal formation. Cell Host Microbe 5(3): 244-58.
- Cell Biology- Prof. Dr. Theresia Stradal