45. Intracellular transport and cytoskeletal organization of a cell is regulated by nucleotide exchange of different small molecular weight GTPases of Ras super family.
Overexpression of which of the following GTPase modulates the actin-cytoskeleton of HeLa cells?
(1) Ran in GDP bound form

(2) Ran in GTP bound form
(3) Rho in GTP bound form
(4) Rho in GDP bound form

 

The overexpression of Rho in its GTP-bound form modulates the actin cytoskeleton of HeLa cells. Studies indicate that Rho GTPases (especially RhoA in its active GTP-bound state) regulate actin-myosin cytoskeletal organization, cell morphology, and cell-cell contacts in HeLa cells. This modulation occurs through Rho GTPase signaling pathways, which play a crucial role in cytoskeletal reorganization. Specifically, when Rho is in its active, GTP-bound form, it influences the actin cytoskeleton dynamics leading to changes in cell shape and behavior.

In contrast, Ran GTPases primarily regulate nuclear transport and microtubule organization during the cell cycle and are not directly linked to actin cytoskeleton modulation in HeLa cells. The GDP-bound forms of these GTPases represent their inactive states and do not promote actin cytoskeleton changes.

Therefore, among the given options, the correct choice is:

(3) Rho in GTP bound form

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