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Suppressor of Cytokine Signaling 2 Negatively Regulates NK Cell Differentiation by Inhibiting JAK2 Activity

View Article: PubMed Central - PubMed

ABSTRACT

Suppressor of cytokine signaling (SOCS) proteins are negative regulators of cytokine responses. Although recent reports have shown regulatory roles for SOCS proteins in innate and adaptive immunity, their roles in natural killer (NK) cell development are largely unknown. Here, we show that SOCS2 is involved in NK cell development. SOCS2−/− mice showed a high frequency of NK cells in the bone marrow and spleen. Knockdown of SOCS2 was associated with enhanced differentiation of NK cells in vitro, and the transplantation of hematopoietic stem cells (HSCs) into congenic mice resulted in enhanced differentiation in SOCS2−/− HSCs. We found that SOCS2 could inhibit Janus kinase 2 (JAK2) activity and JAK2-STAT5 signaling pathways via direct interaction with JAK2. Furthermore, SOCS2−/− mice showed a reduction in lung metastases and an increase in survival following melanoma challenge. Overall, our findings suggest that SOCS2 negatively regulates the development of NK cells by inhibiting JAK2 activity via direct interaction.

No MeSH data available.


Related in: MedlinePlus

Autonomous effects of SOCS2 on NK cell development.Flow cytometric analysis of immune cells from BM or SP of chimeras at 4 months after competitive transplantation of long-term hematopoietic stem cells (LT-HSCs) (CD34−Flk2−LSK, CD45.2+, 5 × 102) with BM cells (CD45.1+, 1 × 106) into lethally irradiated wild-type congenic recipients (CD45.1+). (A) A representative results for NK cell frequency of CD45.2+ BM cells. (B,C) Percentage or numbers of NK cells (CD3−NK1.1+ in the lymphocyte gate) in CD45.2+ BM cells from WT and SOCS2−/− HSCs. n = 5, *p < 0.05, **p < 0.01. (D,E) Percentage or numbers of granulocyte (Gr-1+), macrophage (CD11b+), T cells (CD3+NK1.1−) and B cells (B220+) in CD45.2+ BM cells derived from WT and SOCS2−/− HSCs. (F) A representative results for NK cell frequency of CD45.2+ splenocytes. (G,H) Percentage or numbers of NK cells (CD3−NK1.1+) in CD45.2+ splenocytes from WT and SOCS2−/− HSCs. (I,J) Percentage or numbers of granulocyte (Gr-1+), macrophage (CD11b+), T cells (CD3+NK1.1−) and B cells (B220+) in CD45.2+ splenocytes derived from WT and SOCS2−/− HSCs. Data are from two independent experiments. Statistical significance is indicated as *p < 0.05, **p < 0.01.
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f3: Autonomous effects of SOCS2 on NK cell development.Flow cytometric analysis of immune cells from BM or SP of chimeras at 4 months after competitive transplantation of long-term hematopoietic stem cells (LT-HSCs) (CD34−Flk2−LSK, CD45.2+, 5 × 102) with BM cells (CD45.1+, 1 × 106) into lethally irradiated wild-type congenic recipients (CD45.1+). (A) A representative results for NK cell frequency of CD45.2+ BM cells. (B,C) Percentage or numbers of NK cells (CD3−NK1.1+ in the lymphocyte gate) in CD45.2+ BM cells from WT and SOCS2−/− HSCs. n = 5, *p < 0.05, **p < 0.01. (D,E) Percentage or numbers of granulocyte (Gr-1+), macrophage (CD11b+), T cells (CD3+NK1.1−) and B cells (B220+) in CD45.2+ BM cells derived from WT and SOCS2−/− HSCs. (F) A representative results for NK cell frequency of CD45.2+ splenocytes. (G,H) Percentage or numbers of NK cells (CD3−NK1.1+) in CD45.2+ splenocytes from WT and SOCS2−/− HSCs. (I,J) Percentage or numbers of granulocyte (Gr-1+), macrophage (CD11b+), T cells (CD3+NK1.1−) and B cells (B220+) in CD45.2+ splenocytes derived from WT and SOCS2−/− HSCs. Data are from two independent experiments. Statistical significance is indicated as *p < 0.05, **p < 0.01.

Mentions: Our data indicated that the loss of SOCS2 enhanced NK cell development but did not alter the functional activity of NK cells. NK cells develop from hematopoietic stem cells (HSCs) mainly in the BM29. Next, to avoid the environmental effect on NK cell differentiation in vivo, we isolated HSCs from WT and SOCS2−/− mice to perform a competitive repopulation assay. We transferred HSCs from WT or SOCS2−/− (CD45.2+) mice with competitor BM cells (CD45.1+) into lethally irradiated WT (CD45.1+) congenic mice via intravenous injection. The engraftment of WT or SOCS2−/− HSCs in BM and spleen was shown no significant difference (Figure S1). However, as shown in Fig. 3A–C, the frequency and absolute number of CD3−NK1.1+ cells in BM revealed a significant increase in NK cells derived from SOCS2−/− HSCs. Similarly, we observed an increase in NK cells in the spleen of the SOCS2−/− chimera compared to the WT chimera (Fig. 3F–H). In contrast, we found that the frequency and total number of B cells, T cells, and granulocytes/macrophages were similar between WT and SOCS2−/− chimeras in BM (Fig. 3D,E) and SP (Fig. 3I,J). These results led us to conclude that the role of SOCS2 in NK cell development was autonomous.


Suppressor of Cytokine Signaling 2 Negatively Regulates NK Cell Differentiation by Inhibiting JAK2 Activity
Autonomous effects of SOCS2 on NK cell development.Flow cytometric analysis of immune cells from BM or SP of chimeras at 4 months after competitive transplantation of long-term hematopoietic stem cells (LT-HSCs) (CD34−Flk2−LSK, CD45.2+, 5 × 102) with BM cells (CD45.1+, 1 × 106) into lethally irradiated wild-type congenic recipients (CD45.1+). (A) A representative results for NK cell frequency of CD45.2+ BM cells. (B,C) Percentage or numbers of NK cells (CD3−NK1.1+ in the lymphocyte gate) in CD45.2+ BM cells from WT and SOCS2−/− HSCs. n = 5, *p < 0.05, **p < 0.01. (D,E) Percentage or numbers of granulocyte (Gr-1+), macrophage (CD11b+), T cells (CD3+NK1.1−) and B cells (B220+) in CD45.2+ BM cells derived from WT and SOCS2−/− HSCs. (F) A representative results for NK cell frequency of CD45.2+ splenocytes. (G,H) Percentage or numbers of NK cells (CD3−NK1.1+) in CD45.2+ splenocytes from WT and SOCS2−/− HSCs. (I,J) Percentage or numbers of granulocyte (Gr-1+), macrophage (CD11b+), T cells (CD3+NK1.1−) and B cells (B220+) in CD45.2+ splenocytes derived from WT and SOCS2−/− HSCs. Data are from two independent experiments. Statistical significance is indicated as *p < 0.05, **p < 0.01.
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f3: Autonomous effects of SOCS2 on NK cell development.Flow cytometric analysis of immune cells from BM or SP of chimeras at 4 months after competitive transplantation of long-term hematopoietic stem cells (LT-HSCs) (CD34−Flk2−LSK, CD45.2+, 5 × 102) with BM cells (CD45.1+, 1 × 106) into lethally irradiated wild-type congenic recipients (CD45.1+). (A) A representative results for NK cell frequency of CD45.2+ BM cells. (B,C) Percentage or numbers of NK cells (CD3−NK1.1+ in the lymphocyte gate) in CD45.2+ BM cells from WT and SOCS2−/− HSCs. n = 5, *p < 0.05, **p < 0.01. (D,E) Percentage or numbers of granulocyte (Gr-1+), macrophage (CD11b+), T cells (CD3+NK1.1−) and B cells (B220+) in CD45.2+ BM cells derived from WT and SOCS2−/− HSCs. (F) A representative results for NK cell frequency of CD45.2+ splenocytes. (G,H) Percentage or numbers of NK cells (CD3−NK1.1+) in CD45.2+ splenocytes from WT and SOCS2−/− HSCs. (I,J) Percentage or numbers of granulocyte (Gr-1+), macrophage (CD11b+), T cells (CD3+NK1.1−) and B cells (B220+) in CD45.2+ splenocytes derived from WT and SOCS2−/− HSCs. Data are from two independent experiments. Statistical significance is indicated as *p < 0.05, **p < 0.01.
Mentions: Our data indicated that the loss of SOCS2 enhanced NK cell development but did not alter the functional activity of NK cells. NK cells develop from hematopoietic stem cells (HSCs) mainly in the BM29. Next, to avoid the environmental effect on NK cell differentiation in vivo, we isolated HSCs from WT and SOCS2−/− mice to perform a competitive repopulation assay. We transferred HSCs from WT or SOCS2−/− (CD45.2+) mice with competitor BM cells (CD45.1+) into lethally irradiated WT (CD45.1+) congenic mice via intravenous injection. The engraftment of WT or SOCS2−/− HSCs in BM and spleen was shown no significant difference (Figure S1). However, as shown in Fig. 3A–C, the frequency and absolute number of CD3−NK1.1+ cells in BM revealed a significant increase in NK cells derived from SOCS2−/− HSCs. Similarly, we observed an increase in NK cells in the spleen of the SOCS2−/− chimera compared to the WT chimera (Fig. 3F–H). In contrast, we found that the frequency and total number of B cells, T cells, and granulocytes/macrophages were similar between WT and SOCS2−/− chimeras in BM (Fig. 3D,E) and SP (Fig. 3I,J). These results led us to conclude that the role of SOCS2 in NK cell development was autonomous.

View Article: PubMed Central - PubMed

ABSTRACT

Suppressor of cytokine signaling (SOCS) proteins are negative regulators of cytokine responses. Although recent reports have shown regulatory roles for SOCS proteins in innate and adaptive immunity, their roles in natural killer (NK) cell development are largely unknown. Here, we show that SOCS2 is involved in NK cell development. SOCS2&minus;/&minus; mice showed a high frequency of NK cells in the bone marrow and spleen. Knockdown of SOCS2 was associated with enhanced differentiation of NK cells in vitro, and the transplantation of hematopoietic stem cells (HSCs) into congenic mice resulted in enhanced differentiation in SOCS2&minus;/&minus; HSCs. We found that SOCS2 could inhibit Janus kinase 2 (JAK2) activity and JAK2-STAT5 signaling pathways via direct interaction with JAK2. Furthermore, SOCS2&minus;/&minus; mice showed a reduction in lung metastases and an increase in survival following melanoma challenge. Overall, our findings suggest that SOCS2 negatively regulates the development of NK cells by inhibiting JAK2 activity via direct interaction.

No MeSH data available.


Related in: MedlinePlus