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Interleukin-15 regulates proliferation and self-renewal of adult neural stem cells.

Gómez-Nicola D, Valle-Argos B, Pallas-Bazarra N, Nieto-Sampedro M - Mol. Biol. Cell (2011)

Bottom Line: Moreover, IL-15-deficient NSCs were more prone to differentiate than wild-type NSCs, not affecting the cell population balance.Lack of IL-15 led to a defective activation of the JAK/STAT and ERK pathways, key for the regulation of proliferation and differentiation of NSCs.The results show that IL-15 is a key regulator of neurogenesis in the adult and is essential to understanding diseases with an inflammatory component.

View Article: PubMed Central - PubMed

Affiliation: Functional and Systems Neurobiology Department, Cajal Institute (CSIC), Madrid, Spain. dgomeznicola@gmail.com

ABSTRACT
The impact of inflammation is crucial for the regulation of the biology of neural stem cells (NSCs). Interleukin-15 (IL-15) appears as a likely candidate for regulating neurogenesis, based on its well-known mitogenic properties. We show here that NSCs of the subventricular zone (SVZ) express IL-15, which regulates NSC proliferation, as evidenced by the study of IL-15-/- mice and the effects of acute IL-15 administration, coupled to 5-bromo-2'-deoxyuridine/5-ethynyl-2'-deoxyuridine dual-pulse labeling. Moreover, IL-15 regulates NSC differentiation, its deficiency leading to an impaired generation of neuroblasts in the SVZ-rostral migratory stream axis, recoverable through the action of exogenous IL-15. IL-15 expressed in cultured NSCs is linked to self-renewal, proliferation, and differentiation. IL-15-/- NSCs presented deficient proliferation and self-renewal, as evidenced in proliferation and colony-forming assays and the analysis of cell cycle-regulatory proteins. Moreover, IL-15-deficient NSCs were more prone to differentiate than wild-type NSCs, not affecting the cell population balance. Lack of IL-15 led to a defective activation of the JAK/STAT and ERK pathways, key for the regulation of proliferation and differentiation of NSCs. The results show that IL-15 is a key regulator of neurogenesis in the adult and is essential to understanding diseases with an inflammatory component.

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IL-15 regulates the activation of the ERK and JAK/STAT signaling pathways. (A) Western blotting analysis of the activation of the ERK MAPK pathway. The activation of ERK1 and ERK2 is represented by the phosphorylation degree (up; pERK1/2) in relation to the total protein (down; ERK1/2). (B) Western blotting analysis of the activation of the JAK/STAT pathway. The activation of STAT1, STAT3, and STAT5 is represented by the phosphorylation degree (pSTAT1, pSTAT3, pSTAT5) in relation to the total protein (STAT1, STAT3, STAT5). WT and IL-15 KO neurospheres were treated with complete medium for 5, 10, and 20 min, using cells treated with incomplete medium as controls (WT CTL, IL-15 KO CTL). (C) Effect of the inhibition of IL-15 signaling on the proliferation of neurospheres was evaluated by the MTT assay. In the control conditions, cells were cultured in incomplete medium (CTL) or incomplete medium supplemented with IL-15 (5 ng/ml) for 72 h. Alternatively, cells were treated with PD98059, AG-490, or the combination. Data are expressed as mean ± SEM of OD 595 nm. Statistical differences of CTL vs. IL-15: **p < 0.01. Data were analyzed with an ANOVA and a post hoc Tukey test.
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Figure 8: IL-15 regulates the activation of the ERK and JAK/STAT signaling pathways. (A) Western blotting analysis of the activation of the ERK MAPK pathway. The activation of ERK1 and ERK2 is represented by the phosphorylation degree (up; pERK1/2) in relation to the total protein (down; ERK1/2). (B) Western blotting analysis of the activation of the JAK/STAT pathway. The activation of STAT1, STAT3, and STAT5 is represented by the phosphorylation degree (pSTAT1, pSTAT3, pSTAT5) in relation to the total protein (STAT1, STAT3, STAT5). WT and IL-15 KO neurospheres were treated with complete medium for 5, 10, and 20 min, using cells treated with incomplete medium as controls (WT CTL, IL-15 KO CTL). (C) Effect of the inhibition of IL-15 signaling on the proliferation of neurospheres was evaluated by the MTT assay. In the control conditions, cells were cultured in incomplete medium (CTL) or incomplete medium supplemented with IL-15 (5 ng/ml) for 72 h. Alternatively, cells were treated with PD98059, AG-490, or the combination. Data are expressed as mean ± SEM of OD 595 nm. Statistical differences of CTL vs. IL-15: **p < 0.01. Data were analyzed with an ANOVA and a post hoc Tukey test.

Mentions: Knowing that most of the proliferative and differentiation patterns of NSCs are regulated by the MAPK and JAK/STAT pathways, we wanted to investigate whether these pathways were differentially regulated in IL-15−/− NSCs. Using Western blotting techniques, we observed that WT NSCs showed an increased phosphorylation of extracellular signal-regulated kinase (ERK) 1 and ERK2 when stimulated with EGF and FGF, with maximal values 5 min after the stimulus (Figure 8A). IL-15−/− NSCs present a decreased activation of the ERK1/2 pathway, evidenced by a decrease in the phosphorylation of both ERK and ERK2 when compared with the WT cells (Figure 8A). The JAK/STAT pathway activation was analyzed through the phosphorylation state of STAT1, STAT3, and STAT5. On stimulation with EGF and FGF, WT NSCs present an increased phosphorylation of STAT1, STAT3, and STAT5 (Figure 8B). However, when IL-15 is knocked out, the phosphorylation degree of STAT1, STAT3, and STAT5 decreased to near-resting levels. Only residual phosphorylation was observed in either WT or IL-15−/− NSCs cultured under resting conditions (without EGF and FGF).


Interleukin-15 regulates proliferation and self-renewal of adult neural stem cells.

Gómez-Nicola D, Valle-Argos B, Pallas-Bazarra N, Nieto-Sampedro M - Mol. Biol. Cell (2011)

IL-15 regulates the activation of the ERK and JAK/STAT signaling pathways. (A) Western blotting analysis of the activation of the ERK MAPK pathway. The activation of ERK1 and ERK2 is represented by the phosphorylation degree (up; pERK1/2) in relation to the total protein (down; ERK1/2). (B) Western blotting analysis of the activation of the JAK/STAT pathway. The activation of STAT1, STAT3, and STAT5 is represented by the phosphorylation degree (pSTAT1, pSTAT3, pSTAT5) in relation to the total protein (STAT1, STAT3, STAT5). WT and IL-15 KO neurospheres were treated with complete medium for 5, 10, and 20 min, using cells treated with incomplete medium as controls (WT CTL, IL-15 KO CTL). (C) Effect of the inhibition of IL-15 signaling on the proliferation of neurospheres was evaluated by the MTT assay. In the control conditions, cells were cultured in incomplete medium (CTL) or incomplete medium supplemented with IL-15 (5 ng/ml) for 72 h. Alternatively, cells were treated with PD98059, AG-490, or the combination. Data are expressed as mean ± SEM of OD 595 nm. Statistical differences of CTL vs. IL-15: **p < 0.01. Data were analyzed with an ANOVA and a post hoc Tukey test.
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Related In: Results  -  Collection

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Figure 8: IL-15 regulates the activation of the ERK and JAK/STAT signaling pathways. (A) Western blotting analysis of the activation of the ERK MAPK pathway. The activation of ERK1 and ERK2 is represented by the phosphorylation degree (up; pERK1/2) in relation to the total protein (down; ERK1/2). (B) Western blotting analysis of the activation of the JAK/STAT pathway. The activation of STAT1, STAT3, and STAT5 is represented by the phosphorylation degree (pSTAT1, pSTAT3, pSTAT5) in relation to the total protein (STAT1, STAT3, STAT5). WT and IL-15 KO neurospheres were treated with complete medium for 5, 10, and 20 min, using cells treated with incomplete medium as controls (WT CTL, IL-15 KO CTL). (C) Effect of the inhibition of IL-15 signaling on the proliferation of neurospheres was evaluated by the MTT assay. In the control conditions, cells were cultured in incomplete medium (CTL) or incomplete medium supplemented with IL-15 (5 ng/ml) for 72 h. Alternatively, cells were treated with PD98059, AG-490, or the combination. Data are expressed as mean ± SEM of OD 595 nm. Statistical differences of CTL vs. IL-15: **p < 0.01. Data were analyzed with an ANOVA and a post hoc Tukey test.
Mentions: Knowing that most of the proliferative and differentiation patterns of NSCs are regulated by the MAPK and JAK/STAT pathways, we wanted to investigate whether these pathways were differentially regulated in IL-15−/− NSCs. Using Western blotting techniques, we observed that WT NSCs showed an increased phosphorylation of extracellular signal-regulated kinase (ERK) 1 and ERK2 when stimulated with EGF and FGF, with maximal values 5 min after the stimulus (Figure 8A). IL-15−/− NSCs present a decreased activation of the ERK1/2 pathway, evidenced by a decrease in the phosphorylation of both ERK and ERK2 when compared with the WT cells (Figure 8A). The JAK/STAT pathway activation was analyzed through the phosphorylation state of STAT1, STAT3, and STAT5. On stimulation with EGF and FGF, WT NSCs present an increased phosphorylation of STAT1, STAT3, and STAT5 (Figure 8B). However, when IL-15 is knocked out, the phosphorylation degree of STAT1, STAT3, and STAT5 decreased to near-resting levels. Only residual phosphorylation was observed in either WT or IL-15−/− NSCs cultured under resting conditions (without EGF and FGF).

Bottom Line: Moreover, IL-15-deficient NSCs were more prone to differentiate than wild-type NSCs, not affecting the cell population balance.Lack of IL-15 led to a defective activation of the JAK/STAT and ERK pathways, key for the regulation of proliferation and differentiation of NSCs.The results show that IL-15 is a key regulator of neurogenesis in the adult and is essential to understanding diseases with an inflammatory component.

View Article: PubMed Central - PubMed

Affiliation: Functional and Systems Neurobiology Department, Cajal Institute (CSIC), Madrid, Spain. dgomeznicola@gmail.com

ABSTRACT
The impact of inflammation is crucial for the regulation of the biology of neural stem cells (NSCs). Interleukin-15 (IL-15) appears as a likely candidate for regulating neurogenesis, based on its well-known mitogenic properties. We show here that NSCs of the subventricular zone (SVZ) express IL-15, which regulates NSC proliferation, as evidenced by the study of IL-15-/- mice and the effects of acute IL-15 administration, coupled to 5-bromo-2'-deoxyuridine/5-ethynyl-2'-deoxyuridine dual-pulse labeling. Moreover, IL-15 regulates NSC differentiation, its deficiency leading to an impaired generation of neuroblasts in the SVZ-rostral migratory stream axis, recoverable through the action of exogenous IL-15. IL-15 expressed in cultured NSCs is linked to self-renewal, proliferation, and differentiation. IL-15-/- NSCs presented deficient proliferation and self-renewal, as evidenced in proliferation and colony-forming assays and the analysis of cell cycle-regulatory proteins. Moreover, IL-15-deficient NSCs were more prone to differentiate than wild-type NSCs, not affecting the cell population balance. Lack of IL-15 led to a defective activation of the JAK/STAT and ERK pathways, key for the regulation of proliferation and differentiation of NSCs. The results show that IL-15 is a key regulator of neurogenesis in the adult and is essential to understanding diseases with an inflammatory component.

Show MeSH
Related in: MedlinePlus