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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

IFNγ increases tyrosine STAT1 phosphorylation in Nestin+ SVZ progenitors. (A) Phosphorylation of STAT1 at Tyr701 and JAK2 were induced 15 min after IFNγ (50 ng/mL) addition in primary SVZ cultures. Stimulation of pSTAT3Tyr701, pSTAT3Ser727, and JAK1 were not observed (n = 6 per time point). Total STAT1 and STAT3 were unchanged and actin was the loading control. (B) Double-immunofluorescences staining showed that STAT1Tyr701 immunoreactivity was absent in the control culture. After IFNγ stimulation STAT1Tyr701 (green) was increased exclusively in Nestin+ progenitors (red; n = 4), TO-PRO (blue) labeled all nuclei. (C) The presence of the AG490 STAT1 inhibitor reduced STAT1 phosphorylation (n = 4 per time point). Actin was the loading control. (D) Histogram represents immunoreactivity signal intensity of STAT1Tyr701 per Nestin+ cell after IFNγ stimulation in the presence or absence of AG490 inhibitor. After IFNγ stimulation, phosphorylation of STAT1STyr701 was increased in Nestin+ progenitors and the presence of the JAK2 phosphorylation inhibitor AG490 impeded STAT1 phosphorylation (n = 4). Scale bar: (B) 30 μm. Data are represented as mean ± SEM. **p ≤ 0.01.
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Figure 1: IFNγ increases tyrosine STAT1 phosphorylation in Nestin+ SVZ progenitors. (A) Phosphorylation of STAT1 at Tyr701 and JAK2 were induced 15 min after IFNγ (50 ng/mL) addition in primary SVZ cultures. Stimulation of pSTAT3Tyr701, pSTAT3Ser727, and JAK1 were not observed (n = 6 per time point). Total STAT1 and STAT3 were unchanged and actin was the loading control. (B) Double-immunofluorescences staining showed that STAT1Tyr701 immunoreactivity was absent in the control culture. After IFNγ stimulation STAT1Tyr701 (green) was increased exclusively in Nestin+ progenitors (red; n = 4), TO-PRO (blue) labeled all nuclei. (C) The presence of the AG490 STAT1 inhibitor reduced STAT1 phosphorylation (n = 4 per time point). Actin was the loading control. (D) Histogram represents immunoreactivity signal intensity of STAT1Tyr701 per Nestin+ cell after IFNγ stimulation in the presence or absence of AG490 inhibitor. After IFNγ stimulation, phosphorylation of STAT1STyr701 was increased in Nestin+ progenitors and the presence of the JAK2 phosphorylation inhibitor AG490 impeded STAT1 phosphorylation (n = 4). Scale bar: (B) 30 μm. Data are represented as mean ± SEM. **p ≤ 0.01.

Mentions: The conventional signaling pathway activated by IFNγ involves sequential phosphorylation of the tyrosine residues of the JAK and the STAT proteins, as a primary gene expression regulatory mechanism (Li, 2008). The IFNGR and other surface receptors, such as complement receptor 2, which can translate cell IFNγ activity, have previously been reported in adult SVZ progenitors (Li et al., 2010; Moriyama et al., 2011). We aimed here to evaluate the signaling activity induced by IFNγ in postnatal SVZ progenitors. Stimulation assays with IFNγ in SVZ-dissociated cultures showed rapid phosphorylation of STAT1 at Tyr701 (pSTAT1Tyr701); while STAT3 was not stimulated at Tyr 705 (Figure 1A). Phosphorylation of Ser 727 was not induced in either STAT1 or STAT3 (pSTAT3ser727) (Figure 1A, and data not shown). In addition, its regular mediator, JAK2, was activated; but JAK1 was not (Figure 1A). Double immunofluorescence analysis demonstrated that pSTAT1Tyr701 was absent in the control situation; whereas after IFNγ stimulation, phosphorylation of STAT1 at Tyr 701 was specifically detected in the nuclei of Nestin+ progenitors (Figure 1B). The addition of the JAK2 inhibitor AG490 diminished the STAT1 phosphorylation (pSTAT1Tyr701) as assessed by Western blot (Figure 1C), and it severely reduced the intensity of the immunoreactivity of phosphorylated STAT1 after IFNγ stimulation on Nestin+ progenitors (Figures 1B,D).


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)

IFNγ increases tyrosine STAT1 phosphorylation in Nestin+ SVZ progenitors. (A) Phosphorylation of STAT1 at Tyr701 and JAK2 were induced 15 min after IFNγ (50 ng/mL) addition in primary SVZ cultures. Stimulation of pSTAT3Tyr701, pSTAT3Ser727, and JAK1 were not observed (n = 6 per time point). Total STAT1 and STAT3 were unchanged and actin was the loading control. (B) Double-immunofluorescences staining showed that STAT1Tyr701 immunoreactivity was absent in the control culture. After IFNγ stimulation STAT1Tyr701 (green) was increased exclusively in Nestin+ progenitors (red; n = 4), TO-PRO (blue) labeled all nuclei. (C) The presence of the AG490 STAT1 inhibitor reduced STAT1 phosphorylation (n = 4 per time point). Actin was the loading control. (D) Histogram represents immunoreactivity signal intensity of STAT1Tyr701 per Nestin+ cell after IFNγ stimulation in the presence or absence of AG490 inhibitor. After IFNγ stimulation, phosphorylation of STAT1STyr701 was increased in Nestin+ progenitors and the presence of the JAK2 phosphorylation inhibitor AG490 impeded STAT1 phosphorylation (n = 4). Scale bar: (B) 30 μm. Data are represented as mean ± SEM. **p ≤ 0.01.
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Figure 1: IFNγ increases tyrosine STAT1 phosphorylation in Nestin+ SVZ progenitors. (A) Phosphorylation of STAT1 at Tyr701 and JAK2 were induced 15 min after IFNγ (50 ng/mL) addition in primary SVZ cultures. Stimulation of pSTAT3Tyr701, pSTAT3Ser727, and JAK1 were not observed (n = 6 per time point). Total STAT1 and STAT3 were unchanged and actin was the loading control. (B) Double-immunofluorescences staining showed that STAT1Tyr701 immunoreactivity was absent in the control culture. After IFNγ stimulation STAT1Tyr701 (green) was increased exclusively in Nestin+ progenitors (red; n = 4), TO-PRO (blue) labeled all nuclei. (C) The presence of the AG490 STAT1 inhibitor reduced STAT1 phosphorylation (n = 4 per time point). Actin was the loading control. (D) Histogram represents immunoreactivity signal intensity of STAT1Tyr701 per Nestin+ cell after IFNγ stimulation in the presence or absence of AG490 inhibitor. After IFNγ stimulation, phosphorylation of STAT1STyr701 was increased in Nestin+ progenitors and the presence of the JAK2 phosphorylation inhibitor AG490 impeded STAT1 phosphorylation (n = 4). Scale bar: (B) 30 μm. Data are represented as mean ± SEM. **p ≤ 0.01.
Mentions: The conventional signaling pathway activated by IFNγ involves sequential phosphorylation of the tyrosine residues of the JAK and the STAT proteins, as a primary gene expression regulatory mechanism (Li, 2008). The IFNGR and other surface receptors, such as complement receptor 2, which can translate cell IFNγ activity, have previously been reported in adult SVZ progenitors (Li et al., 2010; Moriyama et al., 2011). We aimed here to evaluate the signaling activity induced by IFNγ in postnatal SVZ progenitors. Stimulation assays with IFNγ in SVZ-dissociated cultures showed rapid phosphorylation of STAT1 at Tyr701 (pSTAT1Tyr701); while STAT3 was not stimulated at Tyr 705 (Figure 1A). Phosphorylation of Ser 727 was not induced in either STAT1 or STAT3 (pSTAT3ser727) (Figure 1A, and data not shown). In addition, its regular mediator, JAK2, was activated; but JAK1 was not (Figure 1A). Double immunofluorescence analysis demonstrated that pSTAT1Tyr701 was absent in the control situation; whereas after IFNγ stimulation, phosphorylation of STAT1 at Tyr 701 was specifically detected in the nuclei of Nestin+ progenitors (Figure 1B). The addition of the JAK2 inhibitor AG490 diminished the STAT1 phosphorylation (pSTAT1Tyr701) as assessed by Western blot (Figure 1C), and it severely reduced the intensity of the immunoreactivity of phosphorylated STAT1 after IFNγ stimulation on Nestin+ progenitors (Figures 1B,D).

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