Figure 3.

Simplified scheme reflecting involvement of ARHGAP22 gene in actin dynamics and cytoskeleton regulation and possible connection of SMN with this process. ARHGAP22 may influence on the activity of RhoB, RhoU, RAC1 GTPases. RhoB GTPase affects ROCK and Formin family of proteins. ROCK is known to phosphorylate myosin light chain, myosin phosphatase and LIM kinase (LIMK). LIMK in its turn phosphorylate and inactivates actin-depolymerizing and severing factor, cofilin. Formin proteins catalyze actin nucleation and polymerization. These processes lead to actin filaments and actomyosin bundles assembly. RAC1 and RhoU GTPase affect actin polymerization through LIMK/cofilin pathway. But the activation of Rho/ROCK pathway may contribute to profilin IIa dephosphorylation and accordingly F-actin destabilization. SMN interacting with profilin IIa may influence on its association with ROCK.