This document summarizes a journal club meeting discussion on the regulation of RhoA and Rac proteins in cell motility and migration. The main points discussed are: 1) Rac, not RhoA, is the actual regulator of RhoA activity. Tiam1 and miR-21 are the main regulators of Rac. 2) Simvastatin increases Rac activity and decreases RhoA activity at both the mRNA and protein levels, indicating a reciprocal relationship between RhoA and Rac. 3) Inhibiting farnesyltransferase (FTase) with FTI-277 disrupts cytoskeletal organization and decreases cell migration, suggesting FTase regulates RhoA. 4) miR-21 and T

1. Rac Rho motion
Amr Al-Haidari MD MSc
Surgery department
Journal club meeting 20.12.2013

2. Rac is the actual regulator of RhoA!
Tiam1 and miR-21 are the main
regulators of Rac
FTase regulates RhoA?
Points to be addressed

4. Small GTPases proteins are involved in cell motility

5. Small GTPases proteins are involved in cell motility
RhoA Rac Cdc42
Membrane
ruffles and
lamellipodia
filopodiaStress fibers
and focal
adhesion

6. Endothelial Cell Migration During
Angiogenesis. Circ Res. 2007;100:782-794
What is the relation
between Rho and Rac?

10. Jacobson, Dudek, Birukov, et al. Simvastatin Alters EC Function and Gene Expression Am. J. Respir.
Cell Mol. Biol. 2004
Simvastatin mode
of Rho/Rac
regulation..!

11. Ruqin Kou et al. Regulation of Rac1
by simvastatin in endothelial cells:
differential roles of AMP-activated
protein kinase and calmodulin-
dependent kinase kinase-beta. J
Biol Chem. 2009 May 29; 284
Statin
increases Rac
activity
Mevalonate and
isopernoids
decrease Rac
activity

12. Was it due to RhoA or Rac??

13. Data Normalized against beta actin and calibrated against Untreated control cells
0
0.5
1
1.5
2
2.5
Simv treated cells
CCL17 treated cells
Foldchanges
Rac1 mRNA
RhoA mRNA
Simvastatin
increases Rac and
decreases RhoA
Reciprocal relation
ship!

14. %ofmigratedcells
__
Vehicle 10 20
*
*
#
CCL17+FTI-277 µM
Pirkko L. Harkonen et al. Inhibition of GGTase-I and FTase disrupts cytoskeletal
organization of human PC-3 prostate cancer cells. Cell Biol. Int. (2010) 34, 815–826
What about
FTi-277?
RhoA mRNA

15. ?
Ras status in
cancers? 30%
mutated

16. miR-21
?
FTi
TIAM1
GGTi

17. Journal of the National Cancer Institute feb.2013
Serum miR-21 as a Diagnostic and Prognostic Biomarkerin Colorectal Cancer

18. Charisa et as. miR-21 and miR-31 Converge on TIAM1 to Regulate Migration and Invasion of
Colon Carcinoma Cells. J Biol Chem. 2010 November 12; 285
Upregulation of miR-21 increases migration
and invasion of colon cancer cells

19. Charisa et as. miR-21 and miR-31 Converge on TIAM1 to Regulate Migration and Invasion of
Colon Carcinoma Cells. J Biol Chem. 2010 November 12; 285

20. Rho/Rac Ratio
If RhoA ˃ Rac Active migration
If Rac ˃ RhoA Active invasion or ?
RhoA ᾱ 1/Rac
miR-21 Tiam1 Rac RhoA
Cell migration control?
FTase
?

21. In conclusion, our novel findings suggest that Rac1 signaling is a key component in the
pathophysiology of acute lung injury triggered by streptococcal M1 protein. Inhibition of Rac1 activity
reduces M1 protein-provoked neutrophil infiltration in the lung via inhibition of CXC chemokine
formation in alveolar macrophages. These results suggest that targeting Rac1 signaling might
be a useful approach in order to protect respiratory function in streptococcal infections.
Streptococcal M1 Protein Triggers Farnesyltransferase-Dependent Formation
of CXC Chemokines in Alveolar Macrophages and Neutrophil Infiltration of the Lungs
Songen Zhanga, Milladur Rahmana, Su Zhanga, Bengt Jeppssona, Heiko Herwaldb and Henrik Thorlaciusa
Our novel findings demonstrate that farnesyltransferase is an important regulator of neutrophil-
mediated acute lung injury triggered by streptococcal M1protein. Moreover, we demonstrate
that inhibition of farnesyltransferase abolishes the macrophage dependent generation of CXC
chemokines in response toM1protein challenge. Thus, we conclude that these
farnesyltransferasedependent mechanisms may, at least in part, help to clarify the
beneficial effects exerted by statins and that targeting farnesyltransferase activity might be useful
in order to protect against respiratory failure in streptococcal infections.
Targeting Rac1 Signaling Inhibits Streptococcal M1 Protein-Induced CXC
Chemokine Formation, Neutrophil Infiltration and Lung Injury
Songen Zhang1, Milladur Rahman1, Su Zhang1, Lei Song1, Heiko Herwald2, Henrik Thorlacius