Smooth Myocytes - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 425

Table 8.16. Signaling pathways involved in migration of vascular smooth myocytes

(Source: [ 784 ]).

Molecular cascade Effect

Ca 2 + -calmodulin-MLCK-myosin-2

Actomyosin fiber contraction

CDC42-WASP-ARP2/3 Actin polymerization

MAP3K3/6-P38MAPK-MAPKAPK-HSP27 Actin polymerization

Rac-WaVe-ARP2/3 Actin polymerization

Rac-PAK1-MLCK-myosin-2 Actomyosin fiber contraction

Ras-Raf-ERK-MLCK-myosin-2 Actomyosin fiber contraction

RhoA-RoCK-MLCP-myosin-2 Actomyosin fiber contraction

RhoA-RoCK-LIMK-cofilin Actin polymerization

RhoA-Dia1 Actin polymerization

Table 8.17. Integrin partners (Source: [ 784 ]).

Partners and targets Effect

BCAR1-CRK-RapGEF1/SOS Activation of small GTPases

FAK1-Src-BCAR1 Signaling

Paxillin-PAK-PIX-GIT1 Formation of focal adhesion complex

α

Vinculin-talin-tensin- -actinin Anchorage of actomyosin fibers

as myosin-2, actin capping and severing proteins, 59 formins, 60 profilin, 61 cofilin, 62

and actin-related protein ARP2-ARP3 complex 63 (Table 8.16 )[ 784 ].
Plasmalemmal proteins such as integrins and their actin-binding partners that
serve as adaptors between the cytoskeleton and focal adhesion plaques, such as
α -actinin, paxillin, talin, and vinculin, regulate formation of nascent focal adhesions

(Table 8.17 ). 64

59 Gelsolin acts as both a severing and capping protein during actin filament turnover. Actin-
filament polymerization and depolymerization by gelsolin is promoted by Ca 2 + and PIP 2 ,
respectively.
60 Formins Dia1 and Dia2 associate with the fast-growing barbed end of actin filament and
contribute to actin polymerization. They operate together with profilin for actin filament extension.
Formins Dia1 and Dia2 are activated by RhoA and CDC42, respectively.
61 Profilin tethers to actin monomers to add G actin at barbed (plus) filament ends.
62 Cofilin promotes F actin depolymerization at pointed (minus) filament ends.
63 The ARP2-ARP3 complex serves as a nucleation site for actin filament branching.
64

α -Actinin attaches actin filaments to dense bodies in smooth myocytes. Paxillin is an adaptor
that is phosphorylated to regulate cell spreading and migration. Talin links integrins to the actin
cytoskeleton either directly or indirectly via -actinin and vinculin. Talin is a substrate for Ca 2 + -

activated peptidase calpain-2. Vinculin anchors F actin to the plasma membrane.

α