Limits...
Oncogenic extracellular HSP70 disrupts the gap-junctional coupling between capillary cells.

Thuringer D, Berthenet K, Cronier L, Jego G, Solary E, Garrido C - Oncotarget (2015)

Bottom Line: In order to explore the effects of extracellular HSP70 on human microvascular endothelial cells (HMEC), we initially used gap-FRAP technique.Extracellular human HSP70 (rhHSP70), but not rhHSP27, blocks the gap-junction intercellular communication (GJIC) between HMEC, disrupts the structural integrity of HMEC junction plaques, and decreases connexin43 (Cx43) expression, which correlates with the phosphorylation of Cx43 serine residues.Therapeutic manipulation of this pathway could be of interest in inflammatory and tumor growth.

View Article: PubMed Central - PubMed

Affiliation: INSERM, U866, Faculty of Medecine, Dijon, France.

ABSTRACT
High levels of circulating heat shock protein 70 (HSP70) are detected in many cancers. In order to explore the effects of extracellular HSP70 on human microvascular endothelial cells (HMEC), we initially used gap-FRAP technique. Extracellular human HSP70 (rhHSP70), but not rhHSP27, blocks the gap-junction intercellular communication (GJIC) between HMEC, disrupts the structural integrity of HMEC junction plaques, and decreases connexin43 (Cx43) expression, which correlates with the phosphorylation of Cx43 serine residues. Further exploration of these effects identified a rapid transactivation of the Epidermal Growth Factor Receptor in a Toll-Like Receptor 4-dependent manner, preceding its internalization. In turn, cytosolic Ca2+ oscillations are generated. Both GJIC blockade and Ca2+ mobilization partially depend on ATP release through Cx43 and pannexin (Panx-1) channels, as demonstrated by blocking activity or expression of channels, and inactivating extracellular ATP. By monitoring dye-spreading into adjacent cells, we show that HSP70 released from human monocytes in response to macrophage colony-stimulating factor, prevents the formation of GJIC between monocytes and HMEC. Therapeutic manipulation of this pathway could be of interest in inflammatory and tumor growth.

No MeSH data available.


Related in: MedlinePlus

Hypothetical model of the inhibitory effects of extracellular HSP70 on the diapedesis of monocytesThe diagram shows the distribution of gap-junctions (double barrel) and hemichannels (single barrel) that can operate between monocytes (M) and endothelial cells of the microvascular wall. M-CSF-stimulated monocytes adhere to the endothelial cell monolayer and release HSP70 that disrupts GJIC between EC contributing to the subsequent release of ATP through Panx-1 and Cx43 hemichannels from endothelial cells. Extracellular HSP70 induce endothelial Ca2+ oscillations without affecting the intercellular tight junction protein, localized between apposed cells. When HSP70 is blocked (siRNA or VER155008), M-CSF-stimulated monocytes communicate with endothelial cells by gap junctions (GJIC), allowing their migration across the endothelial cell monolayer, in an endothelial Ca2+-dependent mechanism (slowed down by BAPTA, a Ca2+ chelator, Suppl. Fig. S5).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4496354&req=5

Figure 8: Hypothetical model of the inhibitory effects of extracellular HSP70 on the diapedesis of monocytesThe diagram shows the distribution of gap-junctions (double barrel) and hemichannels (single barrel) that can operate between monocytes (M) and endothelial cells of the microvascular wall. M-CSF-stimulated monocytes adhere to the endothelial cell monolayer and release HSP70 that disrupts GJIC between EC contributing to the subsequent release of ATP through Panx-1 and Cx43 hemichannels from endothelial cells. Extracellular HSP70 induce endothelial Ca2+ oscillations without affecting the intercellular tight junction protein, localized between apposed cells. When HSP70 is blocked (siRNA or VER155008), M-CSF-stimulated monocytes communicate with endothelial cells by gap junctions (GJIC), allowing their migration across the endothelial cell monolayer, in an endothelial Ca2+-dependent mechanism (slowed down by BAPTA, a Ca2+ chelator, Suppl. Fig. S5).

Mentions: The major contribution of our study is the demonstration that extracellular HSP70, exogenously added or released from human circulating monocytes in response to M-CSF induction, activates a signaling cascade that decreases GJIC activity between HMEC and HMEC/monocytes reducing monocyte transmigration through the endothelium (Fig. 8). Thereby, HSP70 release may play a regulatory role in monocyte diapedesis when invading tissues to differentiate into macrophages or osteoclasts, depending on tissue microenvironment. Therapeutic manipulation of this pathway would be a strategy in various diseases such as chronic inflammatory diseases, osteoporosis, and cancer.


Oncogenic extracellular HSP70 disrupts the gap-junctional coupling between capillary cells.

Thuringer D, Berthenet K, Cronier L, Jego G, Solary E, Garrido C - Oncotarget (2015)

Hypothetical model of the inhibitory effects of extracellular HSP70 on the diapedesis of monocytesThe diagram shows the distribution of gap-junctions (double barrel) and hemichannels (single barrel) that can operate between monocytes (M) and endothelial cells of the microvascular wall. M-CSF-stimulated monocytes adhere to the endothelial cell monolayer and release HSP70 that disrupts GJIC between EC contributing to the subsequent release of ATP through Panx-1 and Cx43 hemichannels from endothelial cells. Extracellular HSP70 induce endothelial Ca2+ oscillations without affecting the intercellular tight junction protein, localized between apposed cells. When HSP70 is blocked (siRNA or VER155008), M-CSF-stimulated monocytes communicate with endothelial cells by gap junctions (GJIC), allowing their migration across the endothelial cell monolayer, in an endothelial Ca2+-dependent mechanism (slowed down by BAPTA, a Ca2+ chelator, Suppl. Fig. S5).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496354&req=5

Figure 8: Hypothetical model of the inhibitory effects of extracellular HSP70 on the diapedesis of monocytesThe diagram shows the distribution of gap-junctions (double barrel) and hemichannels (single barrel) that can operate between monocytes (M) and endothelial cells of the microvascular wall. M-CSF-stimulated monocytes adhere to the endothelial cell monolayer and release HSP70 that disrupts GJIC between EC contributing to the subsequent release of ATP through Panx-1 and Cx43 hemichannels from endothelial cells. Extracellular HSP70 induce endothelial Ca2+ oscillations without affecting the intercellular tight junction protein, localized between apposed cells. When HSP70 is blocked (siRNA or VER155008), M-CSF-stimulated monocytes communicate with endothelial cells by gap junctions (GJIC), allowing their migration across the endothelial cell monolayer, in an endothelial Ca2+-dependent mechanism (slowed down by BAPTA, a Ca2+ chelator, Suppl. Fig. S5).
Mentions: The major contribution of our study is the demonstration that extracellular HSP70, exogenously added or released from human circulating monocytes in response to M-CSF induction, activates a signaling cascade that decreases GJIC activity between HMEC and HMEC/monocytes reducing monocyte transmigration through the endothelium (Fig. 8). Thereby, HSP70 release may play a regulatory role in monocyte diapedesis when invading tissues to differentiate into macrophages or osteoclasts, depending on tissue microenvironment. Therapeutic manipulation of this pathway would be a strategy in various diseases such as chronic inflammatory diseases, osteoporosis, and cancer.

Bottom Line: In order to explore the effects of extracellular HSP70 on human microvascular endothelial cells (HMEC), we initially used gap-FRAP technique.Extracellular human HSP70 (rhHSP70), but not rhHSP27, blocks the gap-junction intercellular communication (GJIC) between HMEC, disrupts the structural integrity of HMEC junction plaques, and decreases connexin43 (Cx43) expression, which correlates with the phosphorylation of Cx43 serine residues.Therapeutic manipulation of this pathway could be of interest in inflammatory and tumor growth.

View Article: PubMed Central - PubMed

Affiliation: INSERM, U866, Faculty of Medecine, Dijon, France.

ABSTRACT
High levels of circulating heat shock protein 70 (HSP70) are detected in many cancers. In order to explore the effects of extracellular HSP70 on human microvascular endothelial cells (HMEC), we initially used gap-FRAP technique. Extracellular human HSP70 (rhHSP70), but not rhHSP27, blocks the gap-junction intercellular communication (GJIC) between HMEC, disrupts the structural integrity of HMEC junction plaques, and decreases connexin43 (Cx43) expression, which correlates with the phosphorylation of Cx43 serine residues. Further exploration of these effects identified a rapid transactivation of the Epidermal Growth Factor Receptor in a Toll-Like Receptor 4-dependent manner, preceding its internalization. In turn, cytosolic Ca2+ oscillations are generated. Both GJIC blockade and Ca2+ mobilization partially depend on ATP release through Cx43 and pannexin (Panx-1) channels, as demonstrated by blocking activity or expression of channels, and inactivating extracellular ATP. By monitoring dye-spreading into adjacent cells, we show that HSP70 released from human monocytes in response to macrophage colony-stimulating factor, prevents the formation of GJIC between monocytes and HMEC. Therapeutic manipulation of this pathway could be of interest in inflammatory and tumor growth.

No MeSH data available.


Related in: MedlinePlus