Transcript Fes/ Fps Gene

Fes/ Fps Gene
Fes: Feline Sarcoma
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Same as Fps: Fujinami poultry sarcoma
A proto-oncogene
Located in the cytoplasm
Encodes a non-receptor protein-tyrosine
kinase
• Fes/Fps and Fer (Fes-related protein) are the
only members of a distinct family of kinases
Predicted Domains
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Amino-terminal FCH domain
Three Coiled-coil domains
Central SH2 domain
Carboxy-terminal kinase domain
FCH Domain
• Unknown structure and function
• Apparent affinity for microtubules
• Functions of homologous FCH regions in other
proteins, such as regulation of cytoskeletal
rearrangements, vesicular transport, and
endocytosis, could provide insight to its function
Three Coiled-Coil Domains
• Coiled-Coil – Quaternary protein structure formed
by two or three  helices interacting with each
other along their length
• Negative regulation of kinase activity
• Mediate oligomerization (see diagram)
• Recruitment of signaling partners
Hypothetical means of regulating oligomerization:
Smithgall et al. 1998
Central SH2 Domain
• Mediates protein-protein interactions that are
essential for the transforming activities of the
oncogenic Fps/Fes kinase (Greer 2002)
• Possible SH2 domain-interacting proteins:
Bcr
Abl (Kinase)
FAK (Focal Adhesion Kinase)
Carboxy-terminus Kinase Domain
• Phosphorylates target proteins
• Possible target proteins:
Bcr
Abl
FAK
Mutations in Coiled-Coil Domains
Experiment: Cheng et al. 2001
• Mutants expressed in myeloid-leukemia cell lines
• One bp deletion in first c-c domain: dramatic
increase in kinase activity
• Cells were less dependent on growth stimulus and
spreading was induced
Mutations in Coiled-Coil Domains
Experiment: Cheng et al. 2001
• One bp mutation in the second c-c domain had no
effect
BUT:
• Double-mutant led to reduced kinase activity
Mutation – Protein Fusion
Peter Greer 2002
Participation in Signal
Transduction Pathways
• Fes/ Fps is thought to act downstream of cytokine
receptors
• Functions of these pathways are unknown
Fes/ Fps is thought to play a role in
regulating…
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Cell-matrix and cell-cell adhesions
Hematopoiesis (controversial)
Cytoskeletal rearrangements
Intracellular signaling
*Bcr-Abl
Fes and Bcr-Abl
• Hematopoietic cells need cytokines in order to
survive and grow
• Bcr-Abl is an oncogene whose expression makes
hematopoietic cells grow independently of
cytokines
• Fes expression in leukemia cells antagonizes the
actions of Bcr-Abl
.: one normal function of the Fes gene is to
suppress a rare oncogene
Lionberger and Smithgall 2000
Review:
• Fes acts downstream
of cytokine receptors
• Hematopoietic cells
need cytokines in
order to survive and
grow
• What will happen
when the Fes gene is
eliminated from an
animal?
Hypothesis:
A mouse lacking both copies of
the Fes gene will not survive
since hematopoiesis will not
function properly.
Results:
• Fes-null mice were healthy and viable!
• Two small problems:
1) the mice had slightly less bone marrow
progenitors and circulating mature myeloid
cells
2) the mice were more sensitive to
Lipopolysaccharide (LPS) (~bacteria)
• Proof: the Fes-null phenotypes were rescued
using a wild-type Fes transgene
Zirngibl et al. 2002
Conclusion:
• Fes is not essential for development and
survival
• The roles of Fes and Fer may be redundant
.:What will happen when to a mouse that
lacks both the Fes and Fer genes?