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IFN gamma regulates proliferation and neuronal differentiation by STAT1 in adult SVZ niche.

Pereira L, Medina R, Baena M, Planas AM, Pozas E - Front Cell Neurosci (2015)

Bottom Line: Interferon gamma (IFNγ) has somewhat controversially been associated with SVZ progenitor proliferation and neurogenesis.The final result is deficient recruitment of newborn neurons to the olfactory bulb (OB), indicating that IFNγ-induced stimulation of neuronal differentiation does not compensate for its antiproliferative effect.We conclude that IFNγ signaling via STAT1 in the SVZ acts dually as an antiproliferative and proneurogenic factor, and thereby regulates neurogenesis in normal adult brains.

View Article: PubMed Central - PubMed

Affiliation: Unit of Brain Ischemia, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) Barcelona, Spain ; Department of Brain Ischemia and Neurodegeneration, Institute of Biomedical Research of Barcelona, Consejo Superior de Investigaciones Científicas (CSIC) Barcelona, Spain.

ABSTRACT
The adult subventricular zone (SVZ) is the main neurogenic niche in normal adult brains of mice and rats. Interferon gamma (IFNγ) has somewhat controversially been associated with SVZ progenitor proliferation and neurogenesis. The in vivo involvement of IFNγ in the physiology of the adult SVZ niche is not fully understood and its intracellular mediators are unknown. Here we show that IFNγ, through activation of its canonical signal transducer and activator of transcription 1 (STAT1) pathway, acts specifically on Nestin+ progenitors by decreasing both progenitor proliferation and the number of cycling cells. In addition, IFNγ increases the number of neuroblasts generated without shifting glial fate determination. The final result is deficient recruitment of newborn neurons to the olfactory bulb (OB), indicating that IFNγ-induced stimulation of neuronal differentiation does not compensate for its antiproliferative effect. We conclude that IFNγ signaling via STAT1 in the SVZ acts dually as an antiproliferative and proneurogenic factor, and thereby regulates neurogenesis in normal adult brains.

No MeSH data available.


Related in: MedlinePlus

In SVZ neural progenitors, IFNγ inhibits cell proliferation, while increasing neuroblast numbers. (A) Histograms showing percentage cell viability (IP), proliferation (BrdU) and number of cells in active cycle (Ki67) in the presence or absence of IFNγ (50 ng/ml) in SVZ primary cultures. IFNγ did not alter cell survival, but reduced cell proliferation (BrdU+) and the number of Ki67+ cells (n = 7). (B) Immunofluorescence pictures of primary SVZ cultures illustrating the reduction of cells in active cell cycle (KI67+) after IFNγ treatment (n = 7). Hoechst (blue) stained all nuclei. (C) Immunofluorescence pictures of SVZ primary cultures illustrating the decrease of Nestin+ progenitors (red) and the increase in neuroblasts (TUBB3+, red) after IFNγ treatment for 4 days (n = 6). The number of GFAP+ cells remained unchanged. Hoechst (blue) stained all nuclei. (D) Graph summarizing the presence of cellular markers after IFNγ treatment. The numbers of TUBB3+ cells increased, while Nestin+ cells decreased in the presence of IFNγ (as percentage of total cells). Glial markers such a GFAP and Olig2 were unchanged (n = 6). (E) IFNγ cultures exhibited a consistent decrease in the number of Nestin/BrdU+ and TUBB3+/BrdU+ cells (n = 6), and a lower proportion of cells which expressed Nestin were in active cell cycle (Ki67+, n = 6). Scale bar (B, C): 30 μm. Data are represented as mean ± SEM. *p < 0.05; **p ≤ 0.01; ***p ≤ 0.001.
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Figure 2: In SVZ neural progenitors, IFNγ inhibits cell proliferation, while increasing neuroblast numbers. (A) Histograms showing percentage cell viability (IP), proliferation (BrdU) and number of cells in active cycle (Ki67) in the presence or absence of IFNγ (50 ng/ml) in SVZ primary cultures. IFNγ did not alter cell survival, but reduced cell proliferation (BrdU+) and the number of Ki67+ cells (n = 7). (B) Immunofluorescence pictures of primary SVZ cultures illustrating the reduction of cells in active cell cycle (KI67+) after IFNγ treatment (n = 7). Hoechst (blue) stained all nuclei. (C) Immunofluorescence pictures of SVZ primary cultures illustrating the decrease of Nestin+ progenitors (red) and the increase in neuroblasts (TUBB3+, red) after IFNγ treatment for 4 days (n = 6). The number of GFAP+ cells remained unchanged. Hoechst (blue) stained all nuclei. (D) Graph summarizing the presence of cellular markers after IFNγ treatment. The numbers of TUBB3+ cells increased, while Nestin+ cells decreased in the presence of IFNγ (as percentage of total cells). Glial markers such a GFAP and Olig2 were unchanged (n = 6). (E) IFNγ cultures exhibited a consistent decrease in the number of Nestin/BrdU+ and TUBB3+/BrdU+ cells (n = 6), and a lower proportion of cells which expressed Nestin were in active cell cycle (Ki67+, n = 6). Scale bar (B, C): 30 μm. Data are represented as mean ± SEM. *p < 0.05; **p ≤ 0.01; ***p ≤ 0.001.

Mentions: To evaluate the direct effect of IFNγ on SVZ progenitors, we grew monolayer primary cultures of dissociated cells from whole postnatal SVZ; as described previously (Pérez-Asensio et al., 2013). The cultures consisted of a heterogeneous cell population in which proliferation and differentiation occurred (Pérez-Asensio et al., 2013). The presence of IFNγ in the culture did not affect cell viability (PI incorporation; Figure 2A); however, cells in proliferation (BrdU+ cells; 11.6 ± 2.1% in controls vs. 4.8 ± 1.2%) or active cell cycle (Ki67+ cells; 28.1 ± 0.9% in controls vs. 16.3 ± 2.1%) were significantly decreased (Figures 2A,B). This indicates an effect of the cytokine on cell proliferation, as previously reported for NSC cultures (Ben-Hur et al., 2003; Wong et al., 2004; Li et al., 2010). Furthermore, phenotype analysis in monolayer cultures by immunofluorescence (Figure 2C) showed that the percentage of Nestin+ cells significantly decreased (62.8 ± 2.7% in controls vs. 54.8 ± 2.9%) in the presence of IFNγ; whereas the percentage of neuroblasts increased (TUBB3+ cells; 55.0 ± 2.4% in controls vs. 67.4 ± 2.5%; Figure 2D). In addition, this cytokine decreased the proportion of Nestin+ progenitors and TUBB3+ cells that incorporate BrdU (11.3 ± 3.1% in controls vs. 5.8 ± 0.9%, and 9.8 ± 1.9 1.95% in controls vs. 1.8 ± 1.3% respectively), as well as the proportion of progenitors (Nestin+) that were in active cell cycle (KI67+; 46.5 ± 3.2% in controls vs. 28.1 ± 2.4%). This suggests a more pronounced differentiation step in the presence of IFNγ (Figure 2E). The proportion of glial progenitors (either Olig2+ or GFAP+ cells) was unchanged after IFNγ treatment (Figure 2D). In order to further explore the effects of IFNγ on neuronal differentiation, SVZ explants were exposed to IFNγ. The results showed that the area of migrating cells moving away from the core of the explants was considerably increased by IFNγ, indicating a more pronounced maturation of progenitors in the presence of this cytokine (Figures 3A,B). This observation could also be explained by impaired cell migration. To rule out this possibility, we performed a migration assay where SVZ explants were confronted by a source of IFNγ (soaked beads). The IFNγ did not induce chemoattractive effects in the SVZ progenitor cultures (data not shown).


IFN gamma regulates proliferation and neuronal differentiation by STAT1 in adult SVZ niche.

Pereira L, Medina R, Baena M, Planas AM, Pozas E - Front Cell Neurosci (2015)

In SVZ neural progenitors, IFNγ inhibits cell proliferation, while increasing neuroblast numbers. (A) Histograms showing percentage cell viability (IP), proliferation (BrdU) and number of cells in active cycle (Ki67) in the presence or absence of IFNγ (50 ng/ml) in SVZ primary cultures. IFNγ did not alter cell survival, but reduced cell proliferation (BrdU+) and the number of Ki67+ cells (n = 7). (B) Immunofluorescence pictures of primary SVZ cultures illustrating the reduction of cells in active cell cycle (KI67+) after IFNγ treatment (n = 7). Hoechst (blue) stained all nuclei. (C) Immunofluorescence pictures of SVZ primary cultures illustrating the decrease of Nestin+ progenitors (red) and the increase in neuroblasts (TUBB3+, red) after IFNγ treatment for 4 days (n = 6). The number of GFAP+ cells remained unchanged. Hoechst (blue) stained all nuclei. (D) Graph summarizing the presence of cellular markers after IFNγ treatment. The numbers of TUBB3+ cells increased, while Nestin+ cells decreased in the presence of IFNγ (as percentage of total cells). Glial markers such a GFAP and Olig2 were unchanged (n = 6). (E) IFNγ cultures exhibited a consistent decrease in the number of Nestin/BrdU+ and TUBB3+/BrdU+ cells (n = 6), and a lower proportion of cells which expressed Nestin were in active cell cycle (Ki67+, n = 6). Scale bar (B, C): 30 μm. Data are represented as mean ± SEM. *p < 0.05; **p ≤ 0.01; ***p ≤ 0.001.
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Figure 2: In SVZ neural progenitors, IFNγ inhibits cell proliferation, while increasing neuroblast numbers. (A) Histograms showing percentage cell viability (IP), proliferation (BrdU) and number of cells in active cycle (Ki67) in the presence or absence of IFNγ (50 ng/ml) in SVZ primary cultures. IFNγ did not alter cell survival, but reduced cell proliferation (BrdU+) and the number of Ki67+ cells (n = 7). (B) Immunofluorescence pictures of primary SVZ cultures illustrating the reduction of cells in active cell cycle (KI67+) after IFNγ treatment (n = 7). Hoechst (blue) stained all nuclei. (C) Immunofluorescence pictures of SVZ primary cultures illustrating the decrease of Nestin+ progenitors (red) and the increase in neuroblasts (TUBB3+, red) after IFNγ treatment for 4 days (n = 6). The number of GFAP+ cells remained unchanged. Hoechst (blue) stained all nuclei. (D) Graph summarizing the presence of cellular markers after IFNγ treatment. The numbers of TUBB3+ cells increased, while Nestin+ cells decreased in the presence of IFNγ (as percentage of total cells). Glial markers such a GFAP and Olig2 were unchanged (n = 6). (E) IFNγ cultures exhibited a consistent decrease in the number of Nestin/BrdU+ and TUBB3+/BrdU+ cells (n = 6), and a lower proportion of cells which expressed Nestin were in active cell cycle (Ki67+, n = 6). Scale bar (B, C): 30 μm. Data are represented as mean ± SEM. *p < 0.05; **p ≤ 0.01; ***p ≤ 0.001.
Mentions: To evaluate the direct effect of IFNγ on SVZ progenitors, we grew monolayer primary cultures of dissociated cells from whole postnatal SVZ; as described previously (Pérez-Asensio et al., 2013). The cultures consisted of a heterogeneous cell population in which proliferation and differentiation occurred (Pérez-Asensio et al., 2013). The presence of IFNγ in the culture did not affect cell viability (PI incorporation; Figure 2A); however, cells in proliferation (BrdU+ cells; 11.6 ± 2.1% in controls vs. 4.8 ± 1.2%) or active cell cycle (Ki67+ cells; 28.1 ± 0.9% in controls vs. 16.3 ± 2.1%) were significantly decreased (Figures 2A,B). This indicates an effect of the cytokine on cell proliferation, as previously reported for NSC cultures (Ben-Hur et al., 2003; Wong et al., 2004; Li et al., 2010). Furthermore, phenotype analysis in monolayer cultures by immunofluorescence (Figure 2C) showed that the percentage of Nestin+ cells significantly decreased (62.8 ± 2.7% in controls vs. 54.8 ± 2.9%) in the presence of IFNγ; whereas the percentage of neuroblasts increased (TUBB3+ cells; 55.0 ± 2.4% in controls vs. 67.4 ± 2.5%; Figure 2D). In addition, this cytokine decreased the proportion of Nestin+ progenitors and TUBB3+ cells that incorporate BrdU (11.3 ± 3.1% in controls vs. 5.8 ± 0.9%, and 9.8 ± 1.9 1.95% in controls vs. 1.8 ± 1.3% respectively), as well as the proportion of progenitors (Nestin+) that were in active cell cycle (KI67+; 46.5 ± 3.2% in controls vs. 28.1 ± 2.4%). This suggests a more pronounced differentiation step in the presence of IFNγ (Figure 2E). The proportion of glial progenitors (either Olig2+ or GFAP+ cells) was unchanged after IFNγ treatment (Figure 2D). In order to further explore the effects of IFNγ on neuronal differentiation, SVZ explants were exposed to IFNγ. The results showed that the area of migrating cells moving away from the core of the explants was considerably increased by IFNγ, indicating a more pronounced maturation of progenitors in the presence of this cytokine (Figures 3A,B). This observation could also be explained by impaired cell migration. To rule out this possibility, we performed a migration assay where SVZ explants were confronted by a source of IFNγ (soaked beads). The IFNγ did not induce chemoattractive effects in the SVZ progenitor cultures (data not shown).

Bottom Line: Interferon gamma (IFNγ) has somewhat controversially been associated with SVZ progenitor proliferation and neurogenesis.The final result is deficient recruitment of newborn neurons to the olfactory bulb (OB), indicating that IFNγ-induced stimulation of neuronal differentiation does not compensate for its antiproliferative effect.We conclude that IFNγ signaling via STAT1 in the SVZ acts dually as an antiproliferative and proneurogenic factor, and thereby regulates neurogenesis in normal adult brains.

View Article: PubMed Central - PubMed

Affiliation: Unit of Brain Ischemia, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) Barcelona, Spain ; Department of Brain Ischemia and Neurodegeneration, Institute of Biomedical Research of Barcelona, Consejo Superior de Investigaciones Científicas (CSIC) Barcelona, Spain.

ABSTRACT
The adult subventricular zone (SVZ) is the main neurogenic niche in normal adult brains of mice and rats. Interferon gamma (IFNγ) has somewhat controversially been associated with SVZ progenitor proliferation and neurogenesis. The in vivo involvement of IFNγ in the physiology of the adult SVZ niche is not fully understood and its intracellular mediators are unknown. Here we show that IFNγ, through activation of its canonical signal transducer and activator of transcription 1 (STAT1) pathway, acts specifically on Nestin+ progenitors by decreasing both progenitor proliferation and the number of cycling cells. In addition, IFNγ increases the number of neuroblasts generated without shifting glial fate determination. The final result is deficient recruitment of newborn neurons to the olfactory bulb (OB), indicating that IFNγ-induced stimulation of neuronal differentiation does not compensate for its antiproliferative effect. We conclude that IFNγ signaling via STAT1 in the SVZ acts dually as an antiproliferative and proneurogenic factor, and thereby regulates neurogenesis in normal adult brains.

No MeSH data available.


Related in: MedlinePlus