Related Experiment Video

Updated: Jun 22, 2026

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
10:27

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Published on: March 9, 2012

RAN GTPase is a RASSF1A effector involved in controlling microtubule organization

Ashraf Dallol1, Luke B Hesson, David Matallanas

  • 1Section of Medical and Molecular Genetics, Institute of Biomedical Research, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. a.dallol@bham.ac.uk

Current Biology : CB
|June 30, 2009
PubMed

Insights

The tumor suppressor gene RASSF1A controls microtubule stability and mitotic spindle integrity. Its loss leads to abnormal cell division and promotes cancer development.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Cancer Research

Background:

  • RASSF1A is a critical tumor suppressor gene frequently inactivated in human cancers via promoter hypermethylation.
  • While RASSF1A interacts with MST1/2 kinases to promote apoptosis, its loss in mice doesn't solely deregulate apoptosis, suggesting other tumor-suppressive mechanisms.
  • The precise molecular pathways governing RASSF1A's tumor suppressor function beyond apoptosis remain incompletely understood.

Purpose of the Study:

  • To elucidate the molecular mechanisms underlying RASSF1A's tumor suppressor activity, focusing on its role beyond apoptosis.
  • To identify novel RASSF1A-interacting proteins and characterize their functional significance in tumor suppression.
  • To investigate the role of RASSF1A in regulating microtubule dynamics and mitotic spindle integrity.

Main Methods:

  • Proteomics screening to identify RASSF1A-interacting proteins.
  • Biochemical assays to analyze protein interactions and phosphorylation events (e.g., MST2-induced RCC1 phosphorylation).
  • Cell-based assays using RASSF1A depletion or expression to assess microtubule stability, mitotic spindle function, and cell cycle progression.

Main Results:

  • Proteomics identified RAN GTPase, MST1/2, and tubulin as RASSF1A interactors.
  • RASSF1A induces microtubule hyperstability dependent on RAN-GTP, achieved through MST2-mediated RCC1 phosphorylation.
  • RASSF1A depletion causes RCC1 mislocalization, leading to mitotic spindle abnormalities, prometaphase arrest, and aneuploidy.

Conclusions:

  • RASSF1A regulates microtubule stability and mitotic spindle integrity through a novel pathway involving RAN GTPase and RCC1.
  • Loss of RASSF1A function compromises cell division fidelity, contributing to aneuploidy and tumorigenesis.
  • These findings reveal a critical mechanism of RASSF1A-mediated tumor suppression linked to maintaining genomic stability.

More Related Videos

Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay13:51

Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay

Published on: November 11, 2018

Comparing the Affinity of GTPase-binding Proteins using Competition Assays10:37

Comparing the Affinity of GTPase-binding Proteins using Competition Assays

Published on: October 8, 2015

Related Concept Videos

Small GTPases - Ras and Rho01:24

Small GTPases - Ras and Rho

Ras and Rho are small monomeric GTPases that act downstream of receptor tyrosine kinase (RTK) and regulate various cellular processes. These GTPases switch between active and inactive states by binding to guanine nucleotides.
Three regulatory proteins control their activity:
GTPases and their Regulation02:14

GTPases and their Regulation

Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒  small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
GTPases and their Regulation02:14

GTPases and their Regulation

Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒  small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Rab Cascades01:25

Rab Cascades

Rab GTPases act in a regulated cascade during membrane fusion, helping the lipid bilayers mix. The Rab family of proteins are active when bound to GTP, and inactive when bound to GDP. Hence, they act as guanine nucleotide-dependent molecular switches. Rab-GTP recognizes and binds to long or short-range tethering proteins to capture the target vesicle. These tethers coordinate with SNAREs on the vesicle and the target membrane to assemble the trans SNARE complex that locks the mixing bilayers.
Rab Proteins01:14

Rab Proteins

Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
The Ras Gene02:38

The Ras Gene

The Ras-gene-encoded proteins are regulators of signaling pathways controlling cell proliferation, differentiation, or cell survival. The Ras-gene family in humans constitutes three primary members—the HRas, NRas, and KRas. These genes code for four functionally distinct yet closely related proteins—the HRas, NRas, KRas4A, and KRas4B. The involvement of mutant Ras genes in human cancer was first discovered in 1982 and is among the most common causes of human tumorigenesis.
Ras is a superfamily...