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Mouse SPNS2 functions as a sphingosine-1-phosphate transporter in vascular endothelial cells.

Hisano Y, Kobayashi N, Yamaguchi A, Nishi T - PLoS ONE (2012)

Bottom Line: However, little is known about the molecular mechanism by which S1P is supplied to extracellular environments such as blood plasma.Here, we show that SPNS2 functions as an S1P transporter in vascular endothelial cells but not in erythrocytes and platelets.Moreover, the plasma S1P concentration of SPNS2-deficient mice was reduced to approximately 60% of wild-type, and SPNS2-deficient mice were lymphopenic.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan.

ABSTRACT
Sphingosine-1-phosphate (S1P), a sphingolipid metabolite that is produced inside the cells, regulates a variety of physiological and pathological responses via S1P receptors (S1P1-5). Signal transduction between cells consists of three steps; the synthesis of signaling molecules, their export to the extracellular space and their recognition by receptors. An S1P concentration gradient is essential for the migration of various cell types that express S1P receptors, such as lymphocytes, pre-osteoclasts, cancer cells and endothelial cells. To maintain this concentration gradient, plasma S1P concentration must be at a higher level. However, little is known about the molecular mechanism by which S1P is supplied to extracellular environments such as blood plasma. Here, we show that SPNS2 functions as an S1P transporter in vascular endothelial cells but not in erythrocytes and platelets. Moreover, the plasma S1P concentration of SPNS2-deficient mice was reduced to approximately 60% of wild-type, and SPNS2-deficient mice were lymphopenic. Our results demonstrate that SPNS2 is the first physiological S1P transporter in mammals and is a key determinant of lymphocyte egress from the thymus.

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SPNS2 does not function in erythrocytes and platelets.(A) Time-dependent S1P release from erythrocytes. Erythrocytes fromwild-type (closed squares, n = 3) andSPNS2-deficient mice (open circles, n = 4) wereincubated with [3H]sphingosine at 37 °C, and[3H]S1P exported into the medium was measuredat the indicated times. S1P release is shown as a percentage: (amount ofsupernatant)/(total amount). (B) Thrombin induced S1P release fromplatelets. Platelets from wild-type (WT, n = 4) andSPNS2-deficient mice (Δ, n = 4) were incubatedin the presence or absence of thrombin, and S1P released into the mediumwas measured by UPLC-MS/MS. The graphs show the average values frommultiple experiments, with error bars representing the standarderror.
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pone-0038941-g006: SPNS2 does not function in erythrocytes and platelets.(A) Time-dependent S1P release from erythrocytes. Erythrocytes fromwild-type (closed squares, n = 3) andSPNS2-deficient mice (open circles, n = 4) wereincubated with [3H]sphingosine at 37 °C, and[3H]S1P exported into the medium was measuredat the indicated times. S1P release is shown as a percentage: (amount ofsupernatant)/(total amount). (B) Thrombin induced S1P release fromplatelets. Platelets from wild-type (WT, n = 4) andSPNS2-deficient mice (Δ, n = 4) were incubatedin the presence or absence of thrombin, and S1P released into the mediumwas measured by UPLC-MS/MS. The graphs show the average values frommultiple experiments, with error bars representing the standarderror.

Mentions: The release of S1P from platelets and erythrocytes has been compared in detail byourselves and by other researchers [22], [23], [31], [32], [33], [34]. Erythrocytes and plateletsare able to produce and secrete S1P. Erythrocytes predominate among blood cells,and appear to be the major contributor to plasma S1P [35]. Therefore, we measured S1Prelease activity in erythrocytes isolated from wild-type or SPNS2-deficientmice. There were no differences in S1P release activity (Figure 6A). Platelets release S1P in astimulus-dependent manner, although the concentration of plasma S1P is notaltered in NF-E2-deficient mice, which lack circulating platelets, or inanti-GPIba antibody-treated mice, which suffer from thrombocytopenia [19],[21], [23], [33]. Thethrombin-induced S1P release from platelets isolated from SPNS2-deficient micewas also comparable to that of wild-type mice (Figure 6B). The numbers of erythrocytes andplatelets in the blood of wild-type and SPNS2-deficient mice were almostequivalent (Figure 4F and4G, and Table S1). Furthermore, Spns2 transcripts werebelow the level detectable by quantitative real-time PCR. These results indicatethat SPNS2 is not involved in S1P production and S1P supply from erythrocytesand platelets.


Mouse SPNS2 functions as a sphingosine-1-phosphate transporter in vascular endothelial cells.

Hisano Y, Kobayashi N, Yamaguchi A, Nishi T - PLoS ONE (2012)

SPNS2 does not function in erythrocytes and platelets.(A) Time-dependent S1P release from erythrocytes. Erythrocytes fromwild-type (closed squares, n = 3) andSPNS2-deficient mice (open circles, n = 4) wereincubated with [3H]sphingosine at 37 °C, and[3H]S1P exported into the medium was measuredat the indicated times. S1P release is shown as a percentage: (amount ofsupernatant)/(total amount). (B) Thrombin induced S1P release fromplatelets. Platelets from wild-type (WT, n = 4) andSPNS2-deficient mice (Δ, n = 4) were incubatedin the presence or absence of thrombin, and S1P released into the mediumwas measured by UPLC-MS/MS. The graphs show the average values frommultiple experiments, with error bars representing the standarderror.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3379171&req=5

pone-0038941-g006: SPNS2 does not function in erythrocytes and platelets.(A) Time-dependent S1P release from erythrocytes. Erythrocytes fromwild-type (closed squares, n = 3) andSPNS2-deficient mice (open circles, n = 4) wereincubated with [3H]sphingosine at 37 °C, and[3H]S1P exported into the medium was measuredat the indicated times. S1P release is shown as a percentage: (amount ofsupernatant)/(total amount). (B) Thrombin induced S1P release fromplatelets. Platelets from wild-type (WT, n = 4) andSPNS2-deficient mice (Δ, n = 4) were incubatedin the presence or absence of thrombin, and S1P released into the mediumwas measured by UPLC-MS/MS. The graphs show the average values frommultiple experiments, with error bars representing the standarderror.
Mentions: The release of S1P from platelets and erythrocytes has been compared in detail byourselves and by other researchers [22], [23], [31], [32], [33], [34]. Erythrocytes and plateletsare able to produce and secrete S1P. Erythrocytes predominate among blood cells,and appear to be the major contributor to plasma S1P [35]. Therefore, we measured S1Prelease activity in erythrocytes isolated from wild-type or SPNS2-deficientmice. There were no differences in S1P release activity (Figure 6A). Platelets release S1P in astimulus-dependent manner, although the concentration of plasma S1P is notaltered in NF-E2-deficient mice, which lack circulating platelets, or inanti-GPIba antibody-treated mice, which suffer from thrombocytopenia [19],[21], [23], [33]. Thethrombin-induced S1P release from platelets isolated from SPNS2-deficient micewas also comparable to that of wild-type mice (Figure 6B). The numbers of erythrocytes andplatelets in the blood of wild-type and SPNS2-deficient mice were almostequivalent (Figure 4F and4G, and Table S1). Furthermore, Spns2 transcripts werebelow the level detectable by quantitative real-time PCR. These results indicatethat SPNS2 is not involved in S1P production and S1P supply from erythrocytesand platelets.

Bottom Line: However, little is known about the molecular mechanism by which S1P is supplied to extracellular environments such as blood plasma.Here, we show that SPNS2 functions as an S1P transporter in vascular endothelial cells but not in erythrocytes and platelets.Moreover, the plasma S1P concentration of SPNS2-deficient mice was reduced to approximately 60% of wild-type, and SPNS2-deficient mice were lymphopenic.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan.

ABSTRACT
Sphingosine-1-phosphate (S1P), a sphingolipid metabolite that is produced inside the cells, regulates a variety of physiological and pathological responses via S1P receptors (S1P1-5). Signal transduction between cells consists of three steps; the synthesis of signaling molecules, their export to the extracellular space and their recognition by receptors. An S1P concentration gradient is essential for the migration of various cell types that express S1P receptors, such as lymphocytes, pre-osteoclasts, cancer cells and endothelial cells. To maintain this concentration gradient, plasma S1P concentration must be at a higher level. However, little is known about the molecular mechanism by which S1P is supplied to extracellular environments such as blood plasma. Here, we show that SPNS2 functions as an S1P transporter in vascular endothelial cells but not in erythrocytes and platelets. Moreover, the plasma S1P concentration of SPNS2-deficient mice was reduced to approximately 60% of wild-type, and SPNS2-deficient mice were lymphopenic. Our results demonstrate that SPNS2 is the first physiological S1P transporter in mammals and is a key determinant of lymphocyte egress from the thymus.

Show MeSH
Related in: MedlinePlus