Examining the Role of Sphingosine Kinase-2 in the Regulation of Endothelial Cell Barrier Integrity
- Microcirculation. 2016 Apr;23(3):248-65. doi: 10.1111/micc.12271.
- 1. Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, South Australia, Australia.
- 2. School of Medicine, University of Adelaide, Adelaide, South Australia, Australia.
- 3. School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia.
Objective: A key mediator of vascular EC barrier integrity, S1P, is derived from phosphorylation of sphingosine by the SK-1 and SK-2. While previous work indicates that SK-1 can regulate EC barrier integrity, whether SK-2 has a similar role remains to be determined.
Methods: A cell impedance assay was used to assess human umbilical vein EC and bone marrow EC barrier integrity in vitro, with application of the SK inhibitors ABC294640, PF543, SKi, and MP-A08. In vivo studies were conducted using intravital microscopy to assess EC barrier integrity in SK-1 (SphK1(-/-)) and SK-2 (SphK2(-/-)) knock-out mice.
Results: Only ABC294640 and MP-A08, which can both inhibit SK-2, caused a decrease in EC barrier integrity in vitro in both cell types. Intravital microscopy revealed that SphK1(-/-) mice had reduced EC barrier integrity compared to WT mice, whereas no change was evident in SphK2(-/-) mice.
Conclusions: Our data suggest that in vitro inhibition of SK-2, can compromise the integrity of the EC monolayer, while SK-1 exerts a more dominant control in vivo. These data may have clinical implications and could aid in the development of new treatments for disorders of vascular barrier function.