Microtubule Cytoskeleton Overview

Microtubules (MTs) are cylindrical polymeric 25-nm tubes composed of parallel bundles of 13 linear protofilaments made up of a/p tubulin heterodimers. Uniform orientation of the protofilaments within the tubule conveys polarity to the entire microtubule. Microtubules continually undergo cyclic polymerization and depolymerization, known as dynamic instability. Post-translational modifications of tubulin molecules, such as acetylation and detyrosi-nation, as well as capping of the microtubules' plus ends, are thought to stabilize and mature microtubules. Microtubules have critically important roles in mitosis, cell migration, and intracellular transport of a large number of proteins and organelles via microtubule-associated proteins (MAPs).

Multiple aspects of endothelial cell motility, including migration, morphological changes, and proliferation as well as control of endothelial cell intracellular tension and contractility, involve cross-linking between the MT and actin microfilament networks. Microtubule distribution and dynamic instability regulate the activity of small GTPase-mediated signal transduction cascades that control microfilament network dynamics due in part to nonmotor MAPs known as MT-associated guanine-nucleotide exchange factors (GEFs), a family of proteins that regulate activity of Rho GTPases. Furthermore, MT depolymeriza-tion results in activation of Rho, stress fiber formation and apoptosis. Inversely, multiple signaling molecules associate with MT and may regulate MT dynamics including Rac1, proteins upstream of Rac1, and mDia1 [4]. It is clear that microtubule distribution and state of assembly/disassembly has a significant impact on the state of endothelial cell intra-cellular tension and contractility.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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