Related Experiment Video

Updated: Aug 10, 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

Rit, a non-lipid-modified Ras-related protein, transforms NIH3T3 cells without activating the ERK, JNK, p38 MAPK or

E V Rusyn1, E R Reynolds, H Shao

  • 1Department of Radiation Oncology, Lineberger Cancer Center, University of North Carolina at Chapel Hill, 27599, USA.

Oncogene
|October 14, 2000
PubMed

Insights

Rit (Ras-like protein in tissues) and Rin (Ras-like protein in neurons) are novel Ras-related proteins. Rit promotes cell growth and transformation, suggesting it utilizes unique pathways for proliferation control.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Oncology

Background:

  • Rit (Ras-like protein in tissues) and Rin (Ras-like protein in neurons) are novel Ras-related GTP-binding proteins with uncharacterized functions.
  • These proteins share approximately 50% sequence identity with Ras, a well-known regulator of cellular processes.

Purpose of the Study:

  • To investigate the biological functions of Rit and Rin in cellular growth control, transformation, and signaling pathways.
  • To determine the specific roles of Rit and Rin in oncogenic transformation and their interactions with other signaling molecules.

Main Methods:

  • Stable expression of constitutively activated Rit [Rit(79L)] and Rin [Rin(78L)] mutants in NIH cells.
  • Assessing cell proliferation in low serum conditions, colony formation in soft agar, and tumor formation in nude mice.
  • Investigating cooperation with Raf, Rho A, and Rac/Rho in focus assays, and analyzing transcriptional activation of SRF, NF-kappaB, Elk-1, and Jun using luciferase reporter constructs.

Main Results:

  • Constitutively activated Rit [Rit(79L)] induced strong growth transformation, including rapid proliferation, soft agar colony formation, and tumorigenesis in vivo.
  • Rit(79L) cooperated with Raf and Rho A to form foci, while Rin(78L) only cooperated with Raf.
  • Rit(79L) stimulated transcription regulated by SRF, NF-kappaB, Elk-1, and Jun, but neither Rit nor Rin activated ERK, JNK, p38, or PI3-K/Akt kinases.
  • Rit-transformed cell growth and survival were dependent on farnesylation, as farnesyltransferase inhibitors induced apoptosis.

Conclusions:

  • Rit, despite lacking canonical lipidation signals, utilizes farnesylation for cell growth and survival, suggesting novel regulatory mechanisms.
  • Rit appears to employ distinct effector pathways compared to Ras for regulating proliferation and transformation.
  • Rin's limited function in NIH3T3 fibroblasts may be due to the absence of appropriate neural-specific effector pathways in this cell line.

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