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Modulation of glial and neuronal migration by lipocalin-2 in zebrafish.

Kim H, Lee S, Park HC, Lee WH, Lee MS, Suk K - Immune Netw (2011)

Bottom Line: Glial cells such as microglia and astrocytes also provide structural and functional support for neurons.Migration and morphological changes of CNS cells are associated with their physiological as well as pathological functions.The conditioned media also increased the number of neuronal processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Science, Korea University Ansan Hospital, Ansan 425-707, Korea.

ABSTRACT

Background: Glial cells are involved in immune and inflammatory responses in the central nervous system (CNS). Glial cells such as microglia and astrocytes also provide structural and functional support for neurons. Migration and morphological changes of CNS cells are associated with their physiological as well as pathological functions. The secreted protein lipocalin-2 (LCN2) has been previously implicated in regulation of diverse cellular processes of glia and neurons, including cell migration and morphology.

Methods: Here, we employed a zebrafish model to analyze the role of LCN2 in CNS cell migration and morphology in vivo. In the first part of this study, we examined the indirect effect of LCN2 on cell migration and morphology of microglia, astrocytes, and neurons cultured in vitro.

Results: Conditioned media collected from LCN2-treated astrocytes augmented migration of glia and neurons in the Boyden chamber assay. The conditioned media also increased the number of neuronal processes. Next, in order to further understand the role of LCN2 in the CNS in vivo, LCN2 was ectopically expressed in the zebrafish spinal cord. Expression of exogenous LCN2 modulated neuronal cell migration in the spinal cord of zebrafish embryos, supporting the role of LCN2 as a cell migration regulator in the CNS.

Conclusion: Thus, LCN2 proteins secreted under diverse conditions may play an important role in CNS immune and inflammatory responses by controlling cell migration and morphology.

No MeSH data available.


Related in: MedlinePlus

The expression of LCN2 attracts developing neurons toward medial position of the spinal cord in zebrafish. The wild-type embryo (A) or her4:lcn2:egfp-injected transgenic embryo (B) was labeled with an anti-Hu antibody to detect neurons at 24 hpf. Arrowheads indicate neurons near the lcn2:egfp-expressing cells. Dotted lines indicate a lateral margin (a) and medial position (b) of the spinal cord. Numbers indicate percentage of neuronal cells in each region. All images are transverse sections of zebrafish spinal cord, dorsal to top. The quantification of cell migration was done by enumerating the migrated cells as described in the Materials and Methods section. The results are mean±SD.
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Figure 4: The expression of LCN2 attracts developing neurons toward medial position of the spinal cord in zebrafish. The wild-type embryo (A) or her4:lcn2:egfp-injected transgenic embryo (B) was labeled with an anti-Hu antibody to detect neurons at 24 hpf. Arrowheads indicate neurons near the lcn2:egfp-expressing cells. Dotted lines indicate a lateral margin (a) and medial position (b) of the spinal cord. Numbers indicate percentage of neuronal cells in each region. All images are transverse sections of zebrafish spinal cord, dorsal to top. The quantification of cell migration was done by enumerating the migrated cells as described in the Materials and Methods section. The results are mean±SD.

Mentions: In the next set of experiments, in vivo role of LCN2 was examined in a zebrafish model. For the ectopic expression of lcn2 in the zebrafish CNS precursor cells, we first generated her4:lcn2:egfp and her4:egfp DNA constructs, which express LCN2-EGFP fusion protein and EGFP alone, respectively, under the control of her4 promoter (21). Each DNA construct was injected into zebrafish embryos at the one-cell stage. Injected embryos were fixed at the 24 hr post fertilization (hpf) and labeled with anti-Hu antibody, which is a marker for neurons in zebrafish CNS (23,24). In the spinal cord of her4:egfp DNA-injected control embryo, EGFP fluorescence was detected in the Hu-non-neuronal precursor cells; Hu+ neurons were normally located in the lateral margin of the spinal cord at the 24 hpf (Fig. 3A). However, her4:lcn2:egfp DNA-injected embryos showed abnormal localization of neurons; neuronal cells near the LCN2:EGFP-expressing cells were located in the more medial position close to the LCN2:EGFP+ cells compared to the control embryo (Fig. 3B), indicating that LCN2 expression attracts neurons. LCN2 expression exerted a similar chemotactic effect, when the number of Hu+ neurons was counted in different regions of the spinal cord, medial position versus lateral margin: percentage of neuronal cells in the medial position of her4:egfp DNA-injected control embryo, 5.60±0.78%; percentage of neuronal cells in the medial position of her4:lcn2:egfp DNA-injected embryos, 11.92±1.39%; the results are mean±SD (n=10; p<0.05) (Fig. 4). These results support that LCN2 regulates CNS cell migration in vivo.


Modulation of glial and neuronal migration by lipocalin-2 in zebrafish.

Kim H, Lee S, Park HC, Lee WH, Lee MS, Suk K - Immune Netw (2011)

The expression of LCN2 attracts developing neurons toward medial position of the spinal cord in zebrafish. The wild-type embryo (A) or her4:lcn2:egfp-injected transgenic embryo (B) was labeled with an anti-Hu antibody to detect neurons at 24 hpf. Arrowheads indicate neurons near the lcn2:egfp-expressing cells. Dotted lines indicate a lateral margin (a) and medial position (b) of the spinal cord. Numbers indicate percentage of neuronal cells in each region. All images are transverse sections of zebrafish spinal cord, dorsal to top. The quantification of cell migration was done by enumerating the migrated cells as described in the Materials and Methods section. The results are mean±SD.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3275702&req=5

Figure 4: The expression of LCN2 attracts developing neurons toward medial position of the spinal cord in zebrafish. The wild-type embryo (A) or her4:lcn2:egfp-injected transgenic embryo (B) was labeled with an anti-Hu antibody to detect neurons at 24 hpf. Arrowheads indicate neurons near the lcn2:egfp-expressing cells. Dotted lines indicate a lateral margin (a) and medial position (b) of the spinal cord. Numbers indicate percentage of neuronal cells in each region. All images are transverse sections of zebrafish spinal cord, dorsal to top. The quantification of cell migration was done by enumerating the migrated cells as described in the Materials and Methods section. The results are mean±SD.
Mentions: In the next set of experiments, in vivo role of LCN2 was examined in a zebrafish model. For the ectopic expression of lcn2 in the zebrafish CNS precursor cells, we first generated her4:lcn2:egfp and her4:egfp DNA constructs, which express LCN2-EGFP fusion protein and EGFP alone, respectively, under the control of her4 promoter (21). Each DNA construct was injected into zebrafish embryos at the one-cell stage. Injected embryos were fixed at the 24 hr post fertilization (hpf) and labeled with anti-Hu antibody, which is a marker for neurons in zebrafish CNS (23,24). In the spinal cord of her4:egfp DNA-injected control embryo, EGFP fluorescence was detected in the Hu-non-neuronal precursor cells; Hu+ neurons were normally located in the lateral margin of the spinal cord at the 24 hpf (Fig. 3A). However, her4:lcn2:egfp DNA-injected embryos showed abnormal localization of neurons; neuronal cells near the LCN2:EGFP-expressing cells were located in the more medial position close to the LCN2:EGFP+ cells compared to the control embryo (Fig. 3B), indicating that LCN2 expression attracts neurons. LCN2 expression exerted a similar chemotactic effect, when the number of Hu+ neurons was counted in different regions of the spinal cord, medial position versus lateral margin: percentage of neuronal cells in the medial position of her4:egfp DNA-injected control embryo, 5.60±0.78%; percentage of neuronal cells in the medial position of her4:lcn2:egfp DNA-injected embryos, 11.92±1.39%; the results are mean±SD (n=10; p<0.05) (Fig. 4). These results support that LCN2 regulates CNS cell migration in vivo.

Bottom Line: Glial cells such as microglia and astrocytes also provide structural and functional support for neurons.Migration and morphological changes of CNS cells are associated with their physiological as well as pathological functions.The conditioned media also increased the number of neuronal processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Medical Science, Korea University Ansan Hospital, Ansan 425-707, Korea.

ABSTRACT

Background: Glial cells are involved in immune and inflammatory responses in the central nervous system (CNS). Glial cells such as microglia and astrocytes also provide structural and functional support for neurons. Migration and morphological changes of CNS cells are associated with their physiological as well as pathological functions. The secreted protein lipocalin-2 (LCN2) has been previously implicated in regulation of diverse cellular processes of glia and neurons, including cell migration and morphology.

Methods: Here, we employed a zebrafish model to analyze the role of LCN2 in CNS cell migration and morphology in vivo. In the first part of this study, we examined the indirect effect of LCN2 on cell migration and morphology of microglia, astrocytes, and neurons cultured in vitro.

Results: Conditioned media collected from LCN2-treated astrocytes augmented migration of glia and neurons in the Boyden chamber assay. The conditioned media also increased the number of neuronal processes. Next, in order to further understand the role of LCN2 in the CNS in vivo, LCN2 was ectopically expressed in the zebrafish spinal cord. Expression of exogenous LCN2 modulated neuronal cell migration in the spinal cord of zebrafish embryos, supporting the role of LCN2 as a cell migration regulator in the CNS.

Conclusion: Thus, LCN2 proteins secreted under diverse conditions may play an important role in CNS immune and inflammatory responses by controlling cell migration and morphology.

No MeSH data available.


Related in: MedlinePlus