Gα12 and Gα13 are α subunits of heterotrimeric G proteins that are expressed in most tissues and activated by over 25 receptors. They have a molecular weight of 43,000 and stimulate RhoA, leading to cytoskeleton reorganization through ROCK, LIMK, and cofilin. Gα12/13 signaling is involved in cancer cell motility and metastasis by regulating actin cytoskeleton structure through RhoA and formation of lamellipodia and filopodia. Silencing Gα12 in prostate cancer cells significantly inhibited wound healing and cell migration, indicating Gα12 promotes prostate cancer metastasis.

1. G alpha 12,13 Protein
Made by:
Adel Mohie
Under supervision of:
DR. Maysaa

3. Gα12/13 are the unique α subunits of a class of
heterotrimeric G proteins along with GαS, Gαi/o,
and Gαq.
α12 and α13 were initially cloned from a mouse
brain cDNA library by PCR and show 67% amino
acid identity with each other but only 35-40%
with other Gα subunits.
These α subunits are expressed in most tissues
and are activated by over 25 receptors
The Gα12/13 polypeptides have a Mol Wt of
43,000

4. in several cell types Gα12 and Gα13 have shown
different subcellular localization with
Gα12 localized to the plasma membrane while
Gα13 localizes to the cyosol and upon stimulation
translocates to the plasma membrane.
Gα12/13 not ribosylated by Pertussis or Cholera
toxin.
Pertussis toxin has proven to be an important
tool in the dissection of G protein-mediated
pathways. Certain a subunits can be ADP-
ribosylated by this toxin, resulting in Uncoupling
the G protein from receptors

5. Gα12/13 stimulates RhoA(Ras homolog gene
family, member A ). RhoA activates ROCK
(Rho-associated, coiled-coil containing protein
kinase 1) which stimulates LIM kinase(actin-
binding kinases that phosphorylate members of
cofilin), which then stimulates cofilin (is a family
of actin binding proteins
which disassembles actin filaments) which
effectively reorganizes the actin cytoskeleton of
the cell.
Gα12/13 Signaling pathway

7. Role of Gα12/13 in Cancer
It is known that in order to metastasize cancer
cells need to acquire motility.
During cell migration, a cell contracts at the
trailing edges.
Cytoskeleton reorganization is also required
for the the formation of lamellipodia and
fillopodia (cytoskeleton actin protein).

8. Rho A is a small GTPase regulated protein
known to control the actin cytoskeleton
structure which results in the formation of stress
fibers. Rho A modulates the actin cytoskeleton
reorganization by activating ROCK which ends
up activating cofilin through LIM kinase
activation.
It has been shown that TXA2 by binding to its
cognate G protein coupled receptor causes the
activation of RhoA which goes on to bring about
actin cytoskeleton reorganization and manifests
in the form of cell motility.

10. Two commercially prepared potent shRNAs,
shRNA- 909 and shRNA-911 were utilized to
investigate their biological effects on prostate
cancer cells.
It is generally believed that G alpha 12/13
promotes the invasiveness as well as cell
proliferation.
.
Inhibition of Gα12/13

11. When analyze the effect of G alpha 12 silencing
on the invasive properties of prostate cancer by
conducting wound-healing assay and chamber
migration assay.
studies showed that silencing of G alpha 12
significantly inhibit the would-healing process as
well as cell migrating ability of prostate cancer
cells.

12. The ability of the cells to close the gap with
subsequent establishment of new cell-cell
contacts depicts the migratory capability of
cancer cells in metastasis.
G alpha 12 shRNAs significantly inhibited the
migration capability of PC-3MM cells.
These results are in full agreement with a recent
finding that G alpha 12 promotes prostate
cancer metastasis.