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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 neurosphere differentiation state. (A) Western blotting analysis of the expression of markers of astrocytes (GFAP), neurons (βIII tubulin), oligodendrocytes (MBP), and neural progenitor cells (DCX) in WT and IL-15 knockout NSCs cultured in differentiating conditions (2% FBS; poly-l-lysine) for 4, 7, or 10 d. (B) Immunocytochemical analysis of the cellular proportions during differentiation of NSCs of WT or IL-15 KO cells. Cells were cultured in differentiating medium (2% FBS; poly-l-lysine) for 4, 7, or 10 d and analyzed for the percent of neurons (βIII tubulin+; black bars), astrocytes (GFAP+; white bars), or oligodendrocytes (O4+; gray bars), expressing data as mean ± SEM of positive cells. Statistical differences of WT vs. IL-15−/−: *p < 0.05. Data were analyzed with an ANOVA and a post hoc Tukey test.
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Figure 7: IL-15 regulates neurosphere differentiation state. (A) Western blotting analysis of the expression of markers of astrocytes (GFAP), neurons (βIII tubulin), oligodendrocytes (MBP), and neural progenitor cells (DCX) in WT and IL-15 knockout NSCs cultured in differentiating conditions (2% FBS; poly-l-lysine) for 4, 7, or 10 d. (B) Immunocytochemical analysis of the cellular proportions during differentiation of NSCs of WT or IL-15 KO cells. Cells were cultured in differentiating medium (2% FBS; poly-l-lysine) for 4, 7, or 10 d and analyzed for the percent of neurons (βIII tubulin+; black bars), astrocytes (GFAP+; white bars), or oligodendrocytes (O4+; gray bars), expressing data as mean ± SEM of positive cells. Statistical differences of WT vs. IL-15−/−: *p < 0.05. Data were analyzed with an ANOVA and a post hoc Tukey test.

Mentions: Taking into account the observed changes in IL-15 expression in NSCs during the course of their differentiation (Figure 5), we proceeded to analyze the effect of IL-15 knockout on the NSC differentiation profile. NSCs were cultured under differentiating conditions (supplemented with 2% FBS) for 4, 7, and 10 d to further analyze the expression of neuronal, astroglial, or oligodendroglial specific markers by Western blotting and immunocytochemistry (Figure 7). First, we observed that IL-15−/− NSCs presented an accelerated and enhanced differentiation pattern when compared with WT NSCs, as deduced from the increased levels of GFAP, βIII tubulin, and myelin basic protein (MBP) (markers of astrocytes, neurons, and oligodendrocytes, respectively) at any analyzed time point (Figure 7A). On the other hand, the expression of DCX was quickly down-regulated in IL-15−/− NSCs compared with WT cells (Figure 7A), indicating a more acute loss of the undifferentiated state. Specifically, we observed in IL-15−/− NSCs that both GFAP and βIII tubulin levels reach their maximum at 4 d, to be maintained for the whole course of differentiation, whereas MBP levels increased progressively with time (Figure 7A).


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 neurosphere differentiation state. (A) Western blotting analysis of the expression of markers of astrocytes (GFAP), neurons (βIII tubulin), oligodendrocytes (MBP), and neural progenitor cells (DCX) in WT and IL-15 knockout NSCs cultured in differentiating conditions (2% FBS; poly-l-lysine) for 4, 7, or 10 d. (B) Immunocytochemical analysis of the cellular proportions during differentiation of NSCs of WT or IL-15 KO cells. Cells were cultured in differentiating medium (2% FBS; poly-l-lysine) for 4, 7, or 10 d and analyzed for the percent of neurons (βIII tubulin+; black bars), astrocytes (GFAP+; white bars), or oligodendrocytes (O4+; gray bars), expressing data as mean ± SEM of positive cells. Statistical differences of WT vs. IL-15−/−: *p < 0.05. Data were analyzed with an ANOVA and a post hoc Tukey test.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 7: IL-15 regulates neurosphere differentiation state. (A) Western blotting analysis of the expression of markers of astrocytes (GFAP), neurons (βIII tubulin), oligodendrocytes (MBP), and neural progenitor cells (DCX) in WT and IL-15 knockout NSCs cultured in differentiating conditions (2% FBS; poly-l-lysine) for 4, 7, or 10 d. (B) Immunocytochemical analysis of the cellular proportions during differentiation of NSCs of WT or IL-15 KO cells. Cells were cultured in differentiating medium (2% FBS; poly-l-lysine) for 4, 7, or 10 d and analyzed for the percent of neurons (βIII tubulin+; black bars), astrocytes (GFAP+; white bars), or oligodendrocytes (O4+; gray bars), expressing data as mean ± SEM of positive cells. Statistical differences of WT vs. IL-15−/−: *p < 0.05. Data were analyzed with an ANOVA and a post hoc Tukey test.
Mentions: Taking into account the observed changes in IL-15 expression in NSCs during the course of their differentiation (Figure 5), we proceeded to analyze the effect of IL-15 knockout on the NSC differentiation profile. NSCs were cultured under differentiating conditions (supplemented with 2% FBS) for 4, 7, and 10 d to further analyze the expression of neuronal, astroglial, or oligodendroglial specific markers by Western blotting and immunocytochemistry (Figure 7). First, we observed that IL-15−/− NSCs presented an accelerated and enhanced differentiation pattern when compared with WT NSCs, as deduced from the increased levels of GFAP, βIII tubulin, and myelin basic protein (MBP) (markers of astrocytes, neurons, and oligodendrocytes, respectively) at any analyzed time point (Figure 7A). On the other hand, the expression of DCX was quickly down-regulated in IL-15−/− NSCs compared with WT cells (Figure 7A), indicating a more acute loss of the undifferentiated state. Specifically, we observed in IL-15−/− NSCs that both GFAP and βIII tubulin levels reach their maximum at 4 d, to be maintained for the whole course of differentiation, whereas MBP levels increased progressively with time (Figure 7A).

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