Limits...
Rafs constitute a nodal point in the regulation of embryonic endothelial progenitor cell growth and differentiation.

Bidzhekov K, Hautmann M, Semisch M, Weber C, Engelmann B, Hatzopoulos AK - J. Cell. Mol. Med. (2007 Nov-Dec)

Bottom Line: Our findings show that both B- and C-Raf kinase domains, when lacking adjacent regulatory parts, are equally effective in inducing eEPC differentiation.In this experimental setting, we found that eEPCs lacking B-Raf failed to differentiate, whereas loss-of C-Raf function primarily slowed cell growth without impairing cAMP-induced differentiation.These findings were further corroborated in B-Raf eEPCs, isolated from the corresponding knockout embryos, which failed to differentiate in vitro.

View Article: PubMed Central - PubMed

Affiliation: GSF-National Research Center for Environment and Health, Institute of Clinical Molecular Biology and Tumor Genetics, Munich, Germany.

ABSTRACT
Mouse embryonic endothelial progenitor cells (eEPCs) acquire a mature phenotype after treatment with cyclic adenosine monophosphate (cAMP), suggesting an involvement of Raf serine/threonine kinases in the differentiation process. To test this idea, we investigated the role of B-Raf and C-Raf in proliferation and differentiation of eEPCs by expressing fusion proteins consisting of the kinase domains from Raf molecules and the hormone binding site of the estrogen receptor (ER), or its variant, the tamoxifen receptor. Our findings show that both B- and C-Raf kinase domains, when lacking adjacent regulatory parts, are equally effective in inducing eEPC differentiation. In contrast, the C-Raf kinase domain is a more potent stimulator of eEPC proliferation than B-Raf. In a complimentary approach, we used siRNA silencing to knockdown endogenously expressed B-Raf and C-Raf in eEPCs. In this experimental setting, we found that eEPCs lacking B-Raf failed to differentiate, whereas loss-of C-Raf function primarily slowed cell growth without impairing cAMP-induced differentiation. These findings were further corroborated in B-Raf eEPCs, isolated from the corresponding knockout embryos, which failed to differentiate in vitro. Thus, gain- and loss-of-function experiments point to distinct roles of B-Raf and C-Raf in regulating growth and differentiation of endothelial progenitor cells, which may harbour therapeutic implications.

Show MeSH

Related in: MedlinePlus

B-Raf and C-Raf have partially overlapping, but distinct roles in eEPCs. The schematic model illustrates the different roles of B- and C-Raf in eEPCs. It appears that B-Raf is primarily involved in cAMP-induced differentiation with a modest effect on eEPC growth. In contrast, C-Raf is a strong inducer of proliferation, but has no role in the cAMP-mediated differentiation process.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4401289&req=5

fig08: B-Raf and C-Raf have partially overlapping, but distinct roles in eEPCs. The schematic model illustrates the different roles of B- and C-Raf in eEPCs. It appears that B-Raf is primarily involved in cAMP-induced differentiation with a modest effect on eEPC growth. In contrast, C-Raf is a strong inducer of proliferation, but has no role in the cAMP-mediated differentiation process.

Mentions: In summary, our results provide a first insight into the molecular mechanisms that drive growth and differentiation of eEPCs. As depicted in Figure 8, differentiation versus proliferation may be promoted by B- or C-Raf respectively, depending probably on the type of extracellular stimuli. Thus, targeting either B- or C-Raf may selectively influence the fate of EPCs in therapeutic interventions. In this light, our findings could be helpful for developing new strategies in the future to enhance EPC growth and differentiation during angiogenesis and tissue repair after injury.


Rafs constitute a nodal point in the regulation of embryonic endothelial progenitor cell growth and differentiation.

Bidzhekov K, Hautmann M, Semisch M, Weber C, Engelmann B, Hatzopoulos AK - J. Cell. Mol. Med. (2007 Nov-Dec)

B-Raf and C-Raf have partially overlapping, but distinct roles in eEPCs. The schematic model illustrates the different roles of B- and C-Raf in eEPCs. It appears that B-Raf is primarily involved in cAMP-induced differentiation with a modest effect on eEPC growth. In contrast, C-Raf is a strong inducer of proliferation, but has no role in the cAMP-mediated differentiation process.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4401289&req=5

fig08: B-Raf and C-Raf have partially overlapping, but distinct roles in eEPCs. The schematic model illustrates the different roles of B- and C-Raf in eEPCs. It appears that B-Raf is primarily involved in cAMP-induced differentiation with a modest effect on eEPC growth. In contrast, C-Raf is a strong inducer of proliferation, but has no role in the cAMP-mediated differentiation process.
Mentions: In summary, our results provide a first insight into the molecular mechanisms that drive growth and differentiation of eEPCs. As depicted in Figure 8, differentiation versus proliferation may be promoted by B- or C-Raf respectively, depending probably on the type of extracellular stimuli. Thus, targeting either B- or C-Raf may selectively influence the fate of EPCs in therapeutic interventions. In this light, our findings could be helpful for developing new strategies in the future to enhance EPC growth and differentiation during angiogenesis and tissue repair after injury.

Bottom Line: Our findings show that both B- and C-Raf kinase domains, when lacking adjacent regulatory parts, are equally effective in inducing eEPC differentiation.In this experimental setting, we found that eEPCs lacking B-Raf failed to differentiate, whereas loss-of C-Raf function primarily slowed cell growth without impairing cAMP-induced differentiation.These findings were further corroborated in B-Raf eEPCs, isolated from the corresponding knockout embryos, which failed to differentiate in vitro.

View Article: PubMed Central - PubMed

Affiliation: GSF-National Research Center for Environment and Health, Institute of Clinical Molecular Biology and Tumor Genetics, Munich, Germany.

ABSTRACT
Mouse embryonic endothelial progenitor cells (eEPCs) acquire a mature phenotype after treatment with cyclic adenosine monophosphate (cAMP), suggesting an involvement of Raf serine/threonine kinases in the differentiation process. To test this idea, we investigated the role of B-Raf and C-Raf in proliferation and differentiation of eEPCs by expressing fusion proteins consisting of the kinase domains from Raf molecules and the hormone binding site of the estrogen receptor (ER), or its variant, the tamoxifen receptor. Our findings show that both B- and C-Raf kinase domains, when lacking adjacent regulatory parts, are equally effective in inducing eEPC differentiation. In contrast, the C-Raf kinase domain is a more potent stimulator of eEPC proliferation than B-Raf. In a complimentary approach, we used siRNA silencing to knockdown endogenously expressed B-Raf and C-Raf in eEPCs. In this experimental setting, we found that eEPCs lacking B-Raf failed to differentiate, whereas loss-of C-Raf function primarily slowed cell growth without impairing cAMP-induced differentiation. These findings were further corroborated in B-Raf eEPCs, isolated from the corresponding knockout embryos, which failed to differentiate in vitro. Thus, gain- and loss-of-function experiments point to distinct roles of B-Raf and C-Raf in regulating growth and differentiation of endothelial progenitor cells, which may harbour therapeutic implications.

Show MeSH
Related in: MedlinePlus