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Water Channels Aquaporin 4 and -1 Expression in Subependymoma Depends on the Localization of the Tumors.

Noell S, Fallier-Becker P, Mack AF, Hoffmeister M, Beschorner R, Ritz R - PLoS ONE (2015)

Bottom Line: In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples.On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found.This was similar to our previous findings in malignant glioblastomas.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, University of Tuebingen, Tuebingen, Germany.

ABSTRACT

Background: We analyzed aquaporin 4 and -1 expression in subependymomas, benign and slow growing brain tumors WHO grade I. Ten subependymoma cases were investigated, five of the fossa inferior and five of the fossa superior.

Methods and results: Using immunohistochemistry, we observed different aquaporin expression patterns depending on localization: aquaporin 4 and -1 were detected in infratentorial subependymomas in the entire tumor tissue. In contrast, supratentorial subependymomas revealed aquaporin 4 and -1 expression only in border areas of the tumor. PCR analyses however showed no difference in aquaporin 4 expression between all subependymomas independent of localization but at higher levels than in normal brain. In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples. The reason for the different distribution pattern of aquaporin 4 in subependymomas still remains unclear. On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found. This was similar to our previous findings in malignant glioblastomas. From these studies, we know that extracellular matrix molecules within the tumor like agrin and its receptor alpha-dystroglycan are involved in forming orthogonal arrays of particles. In subependymomas neither agrin nor alpha-dystroglycan were detected around blood vessels.

Conclusions: Taken together, we show in this study that in the benign subependymomas aquaporins 1 and 4 are dramatically redistributed and upregulated. We speculate that extracellular environments of infra- and supratentorial subependymomas are different and lead to different distribution patterns of aquaporin 4 and -1.

No MeSH data available.


Related in: MedlinePlus

Immunhistological staining of agrin (A-D) and alpha-dystroglycan (E-H) in SE.Neither infratentorial SE (A, C, E, G, patient 5) nor supratentorial SE (B, D, F, G, patient 9) were positive for agrin or dystroglycan, normally found around the blood vessels (for positive control see supplement S3 Fig Bar 1000 and 50μm.
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pone.0131367.g007: Immunhistological staining of agrin (A-D) and alpha-dystroglycan (E-H) in SE.Neither infratentorial SE (A, C, E, G, patient 5) nor supratentorial SE (B, D, F, G, patient 9) were positive for agrin or dystroglycan, normally found around the blood vessels (for positive control see supplement S3 Fig Bar 1000 and 50μm.

Mentions: Next, we used freeze fracture electron microscopy to test for AQP4 forming OAPs and compared samples of all SEs to healthy rat brain tissue (Fig 6B). AQP4 did not form any OAPs in infratentorial SEs (Fig 6A) despite the strong immunoreactivity (c.p. Fig 2). Freeze fracture replica of supratentorial SE also showed no OAPs (data not shown). It is known from our previous studies that the formation of OAPs is dependent on the presence of agrin and α-dystroglycan around the vessels. As shown in Fig 7, neither agrin nor α-dystroglycan could be detected in infratentorial and supratentorial SEs around the blood vessels. MMP2 and 9 as well as MMP3 were also not clearly displayed of any SEs near the vessels in the tumors (Fig 8). Positive and negative controls are depicted in S3 Fig. All results are summarized in Table 4.


Water Channels Aquaporin 4 and -1 Expression in Subependymoma Depends on the Localization of the Tumors.

Noell S, Fallier-Becker P, Mack AF, Hoffmeister M, Beschorner R, Ritz R - PLoS ONE (2015)

Immunhistological staining of agrin (A-D) and alpha-dystroglycan (E-H) in SE.Neither infratentorial SE (A, C, E, G, patient 5) nor supratentorial SE (B, D, F, G, patient 9) were positive for agrin or dystroglycan, normally found around the blood vessels (for positive control see supplement S3 Fig Bar 1000 and 50μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482577&req=5

pone.0131367.g007: Immunhistological staining of agrin (A-D) and alpha-dystroglycan (E-H) in SE.Neither infratentorial SE (A, C, E, G, patient 5) nor supratentorial SE (B, D, F, G, patient 9) were positive for agrin or dystroglycan, normally found around the blood vessels (for positive control see supplement S3 Fig Bar 1000 and 50μm.
Mentions: Next, we used freeze fracture electron microscopy to test for AQP4 forming OAPs and compared samples of all SEs to healthy rat brain tissue (Fig 6B). AQP4 did not form any OAPs in infratentorial SEs (Fig 6A) despite the strong immunoreactivity (c.p. Fig 2). Freeze fracture replica of supratentorial SE also showed no OAPs (data not shown). It is known from our previous studies that the formation of OAPs is dependent on the presence of agrin and α-dystroglycan around the vessels. As shown in Fig 7, neither agrin nor α-dystroglycan could be detected in infratentorial and supratentorial SEs around the blood vessels. MMP2 and 9 as well as MMP3 were also not clearly displayed of any SEs near the vessels in the tumors (Fig 8). Positive and negative controls are depicted in S3 Fig. All results are summarized in Table 4.

Bottom Line: In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples.On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found.This was similar to our previous findings in malignant glioblastomas.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, University of Tuebingen, Tuebingen, Germany.

ABSTRACT

Background: We analyzed aquaporin 4 and -1 expression in subependymomas, benign and slow growing brain tumors WHO grade I. Ten subependymoma cases were investigated, five of the fossa inferior and five of the fossa superior.

Methods and results: Using immunohistochemistry, we observed different aquaporin expression patterns depending on localization: aquaporin 4 and -1 were detected in infratentorial subependymomas in the entire tumor tissue. In contrast, supratentorial subependymomas revealed aquaporin 4 and -1 expression only in border areas of the tumor. PCR analyses however showed no difference in aquaporin 4 expression between all subependymomas independent of localization but at higher levels than in normal brain. In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples. The reason for the different distribution pattern of aquaporin 4 in subependymomas still remains unclear. On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found. This was similar to our previous findings in malignant glioblastomas. From these studies, we know that extracellular matrix molecules within the tumor like agrin and its receptor alpha-dystroglycan are involved in forming orthogonal arrays of particles. In subependymomas neither agrin nor alpha-dystroglycan were detected around blood vessels.

Conclusions: Taken together, we show in this study that in the benign subependymomas aquaporins 1 and 4 are dramatically redistributed and upregulated. We speculate that extracellular environments of infra- and supratentorial subependymomas are different and lead to different distribution patterns of aquaporin 4 and -1.

No MeSH data available.


Related in: MedlinePlus