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Golgi screen identifies the RhoGEF Solo as a novel regulator of RhoB and endocytic transport
C. Lungu, F. Meyer, M. Hörning, J. Steudle, A. Braun, B. Noll, D. Benz, F. Fränkle, S. Schmid, S.A. Eisler and M.A. Olayioye
Traffic, 1-15, 2023
- doi : 10.1111/tra.12880

Brief Summary: ''... Here, a microscopy-based RNAi screen was performed, and the RhoGEF protein Solo was identified as a functional counterplayer of DLC3, a RhoGAP protein with established roles in membrane trafficking. Biochemical, imaging and optogenetics assays further uncover Solo as a novel regulator of endosomal RhoB. Solo and DLC3 was found to control not only the activity, but also total protein levels of RhoB in an antagonistic manner. Together, the results of the study uncover the first functionally connected RhoGAP-RhoGEF pair at endomembranes, placing Solo and DLC3 at the core of endocytic trafficking.''

Optimization of Mechanosensitive Cross-talk between Matrix Stiffness and Protein Density: Independent Matrix Properties Regulate Spreading Dynamics of Myocytes
J. Brock, J. Erhardt, S.A. Eisler, and M. Hörning
Cells, 11, 2122, 2022
- doi : 10.3390/cells11132122

Brief Summary: ''... Here, C2C12 myocytes were monitored on L-DOPA functionalized hydrogels of 22 different elasticity and fibronectin density compositions. We observed a fibronectin density independent increase of the projected cell area until 12 kPa and an optimal fibronectin density at about 2.6 μg/cm² with a maximum actin filament to cell area ratio of 7.5%. The proliferation evaluation of cells showed an opposite correlation between cell spreading duration and speed to the matrix elasticity and protein density, which did not affect the cell cycle duration.''

Correlation of mitochondrial TOM core complex stop-and-go and open-closed
S. Wang, L. Findeisen, S. Leptihn, M.I. Wallace, M. Hörning and S. Nussberger
Communications Biology, 5, 471, 2022
- doi : 10.1038/s42003-022-03419-4

Brief Summary: ''... Here we show the correlation between lateral protein diffusion and channel activity of the general protein import pore of mitochondria (TOM-CC) in membranes resting on ultrathin hydrogel films. We find that TOM-CC switches reversibly between three states of ion permeability associated with protein diffusion. We explain this behavior by the mechanical interaction between the hydrogel and the two β-barrel pores of TOM-CC.''

Galvanotaxis of ciliates: Spatiotemporal dynamics of Coleps hirtus under electric fields
A. Daul, M.-L. Lemloh, and M. Hörning
New Journal of Physics, 24, 053040, 2022
- doi : 10.1088/1367-2630/ac6c47

Brief Summary: ''... Here, we statistically analyze the galvanotactic dynamics of C. hirtus by automated cell tracking routines. We found that the number of cells that show a galvanotactic response, increases with the increase of the applied electric field strength. The spatiotemporal swimming dynamics change and lead to a statistical increase of linear elongated cell trajectories that point toward the cathode. Further, the increase of the electric fields decreases the mean velocity variance, while showing no significant change in the absolute velocity for any applied electric field.''

Hörning et al., Front. Cell Dev. Biol. 2021

Local membrane curvature pins and guides excitable membrane waves in chemotactic and macropinocytic cells - biomedical insights from an innovative simple model
M. Hörning, T. Bullmann and T. Shibata
Frontiers in Cell and Developmental Biology, 9, 2467, 2021
- doi : 10.3389/fcell.2021.670943

Brief Summary: ''... Here, using 3D spatial fluctuation and phase map analysis on actin polymerization inhibited Dictyostelium cells, we reveal a spatial asymmetry of PIP3 signaling on the membrane that is mediated by the contact perimeter of the plasma membrane. We show that the contact perimeter guides PIP3 waves and acts as a pinning site of PIP3 phase singularities. The contact perimeter serves as a diffusion influencing boundary that is regulated by a cell size- and shape-dependent curvature.''