A Cell has a cytoskeleton that provides mechanical support to it. Instead of bones like in human skeleton, the cytoskeleton of cells is made up of Filamentous proteins, known as microtubules, Microfilaments(actin filament) and Intermediate filaments.
Microtubules are make up of Alpha and Beta tubilin,and by joining them together, it forms a protofilament and 13 of them will form a hollow cylinder. They are also polarized with a plus end and a minus end. It is spread throughout the cell with the minus end attaching to centrosome. All this allow the length of microtubules to be able to become longer through assembly or shorter through disassembly. This ability is known as dynamic instability and is important for microtubules to perform its functions.
Firstly it helps in intracellular transport, The motor proteins kinesin and dynein, will utilize the microtubule network to transport vesicles from one part of the cell to another. Vesicles contain proteins such as neurotransmitters or digestive enzymes.
Other than that Microtubules also help in cell division and providing structural support for the cell.As I had mension above the minus ends of microtubules are anchored in the centrosome, which is usually located next to the nucleus and microtubule networks will radiate out from the centrosome to provide the basic organization of the cytoplasm, including the positioning of organelles and the shape of the cells .
Lastly Microtubule also forms the spindle fibre that is needed for cell division.When a cell is about to divide, the centrosomes would migrate to the two opposite poles and the microtubules growing out of the centrosome also known as spindle fibres in this case will help to align the chromosomes during metaphase and pull the sister chromatids apart during anaphase.
Therefore drugs that target and inhibit the microtubules would therefore inhibit cell division, which is the mechanism of action for many anti-cancer drugs.Reason being that the microtubules will be destroyed and it can’t turn into spindle fibre which will affect the Metaphase and the phase afterwards as sister chromatin wouldn’t be aligned and pull apart .Other than that the cell will also lost it structural support and its mean of intracellular transport.This mean that it will be weaker and are unable to get most of the materials it needs resulting in death of cell.
Microfilaments(actin filament) ,on the other hand are made up of globular (G-actin) monomers which polymerize to form filaments (F actin). They are found in filopodia and lamellipodia, which are located at the cell membrane.
Microfilament are able to rapidly polymerize and depolymerize, to allow the cell to move.Other than that it also help in cell division and intracellular transport.
Microfilament are able to form contractile ring with the help of motor protein myosin II . It will be used in the last step in the cell division where the cell is split into two. Contraction of the ring will cause the plasma membrane to be pulled inward and break into two
Therefore drugs that target and inhibit the microfilament would also inhibit cell division.As the microfilament will be destroyed and it can’t turn into contractile ring which will affect the cytokinesis phase of cell division as the mother cell wouldn’t be able to split into two daughter cell.Other than that the cell will also lost it mean of transport and intracellular transport.This mean that it will be unable to move away from protential treat and are unable to get most of the materials it need resulting in death of cell.
Intermediate filaments,however are made up of different monomer depending on cell type.Lamin are the only type that is found in all cells as it is in the nucleus.It is found extend across cytoplasm. It provides mechanical strength to the cell so that it will not be destroyed so easily.
Therefore drugs that target and inhibit the Intemediate filament would result in cell losing mechanical strength to protect the cell which result in weaker cells and easy death.