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Astrocytes in the optic nerve head express putative mechanosensitive channels.

Choi HJ, Sun D, Jakobs TC - Mol. Vis. (2015)

Bottom Line: TRPP2 also showed higher expression in the optic nerve head.Astrocytes in the optic nerve head express multiple putative mechanosensitive channels, in particular the recently identified channels Piezo1 and 2.The expression of putative mechanosensitive channels in these cells may contribute to their responsiveness to traumatic or glaucomatous injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA.

ABSTRACT

Purpose: To establish whether optic nerve head astrocytes express candidate molecules to sense tissue stretch.

Methods: We used conventional PCR, quantitative PCR, and single-cell reverse transcription PCR (RT-PCR) to assess the expression of various members of the transient receptor potential (TRP) channel family and of the recently characterized mechanosensitive channels Piezo1 and 2 in optic nerve head tissue and in single, isolated astrocytes.

Results: Most TRP subfamilies (TRPC, TRPM, TRPV, TRPA, and TRPP) and Piezo1 and 2 were expressed in the optic nerve head of the mouse. Quantitative real-time PCR analysis showed that TRPC1, TRPM7, TRPV2, TRPP2, and Piezo1 are the dominant isoforms in each subfamily. Single-cell RT-PCR revealed that many TRP isoforms, TRPC1-2, TRPC6, TRPV2, TRPV4, TRPM2, TRPM4, TRPM6-7, TRPP1-2, and Piezo1-2, are expressed in astrocytes of the optic nerve head, and that most astrocytes express TRPC1 and TRPP1-2. Comparisons of the TRPP and Piezo expression levels between different tissue regions showed that Piezo2 expression was higher in the optic nerve head and the optic nerve proper than in the brain and the corpus callosum. TRPP2 also showed higher expression in the optic nerve head.

Conclusions: Astrocytes in the optic nerve head express multiple putative mechanosensitive channels, in particular the recently identified channels Piezo1 and 2. The expression of putative mechanosensitive channels in these cells may contribute to their responsiveness to traumatic or glaucomatous injury.

No MeSH data available.


Related in: MedlinePlus

Fold changes in TRPP and Piezo expression levels in three mouse models of optic nerve damage. (A–B) an elevated intraocular pressure (IOP) model, (C–D) an optic nerve crush injury model, and (E–F) glaucomatous DBA/2J mice. Quantitative real-time PCR was performed to assess TRPP and Piezo mRNAs in the optic nerve head prepared from each model (n=3 biologic replicates per time point/severity of glaucoma). The mRNA levels after the elevation in IOP, optic nerve crush, and in glaucomatous degeneration were normalized to the contralateral control eyes (A–D) and control animals with no or early glaucoma (NOE; E–F), and then presented on a log2 scale. Dashed lines represent the mRNA levels of transient receptor potential (TRP) TRPP and Piezo channels in the control groups. Error bar, mean ± SEM.
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f6: Fold changes in TRPP and Piezo expression levels in three mouse models of optic nerve damage. (A–B) an elevated intraocular pressure (IOP) model, (C–D) an optic nerve crush injury model, and (E–F) glaucomatous DBA/2J mice. Quantitative real-time PCR was performed to assess TRPP and Piezo mRNAs in the optic nerve head prepared from each model (n=3 biologic replicates per time point/severity of glaucoma). The mRNA levels after the elevation in IOP, optic nerve crush, and in glaucomatous degeneration were normalized to the contralateral control eyes (A–D) and control animals with no or early glaucoma (NOE; E–F), and then presented on a log2 scale. Dashed lines represent the mRNA levels of transient receptor potential (TRP) TRPP and Piezo channels in the control groups. Error bar, mean ± SEM.

Mentions: For the TRPP channels, no upregulation was seen in the three mouse models. TRPP1 was downregulated 1 week after short-term elevation in IOP (Figure 6A), and TRPP1 and 2 were downregulated 1 day after the optic nerve crush injury (Figure 6C), but the gene expression changes were not significant. Piezo1 did not show obvious up- or downregulation in any of the three models except 3 days after the crush injury, but Piezo2 showed considerable changes in gene expression. One hour after the elevation of IOP, Piezo2 was downregulated, and the expression level was about 40% of the contralateral control (Figure 6B). In the optic nerve crush model, Piezo2 showed a tendency to be upregulated at most recovery intervals (3 days, 1 week, 3 weeks) although the increases in gene expression were not significant (3 days: 22.43±18.48, 1 week: 7.78±2.35, 3 weeks: 10.39±4.65 compared to the contralateral control; n=3, Figure 6D). The Piezo2 mRNA levels 3 days after the optic nerve crush displayed high variation among the biologic replicates. Piezo2 expression also showed a tendency to be upregulated in moderate and severe glaucoma in the DBA/2J mice, and the relative expression levels were 5.86±3.08 and 7.81±1.92, respectively (n=3). Note that all relative expression levels seen in Figure 6 are presented on a log2 scale to show up- and downregulation of the genes compared to the control groups.


Astrocytes in the optic nerve head express putative mechanosensitive channels.

Choi HJ, Sun D, Jakobs TC - Mol. Vis. (2015)

Fold changes in TRPP and Piezo expression levels in three mouse models of optic nerve damage. (A–B) an elevated intraocular pressure (IOP) model, (C–D) an optic nerve crush injury model, and (E–F) glaucomatous DBA/2J mice. Quantitative real-time PCR was performed to assess TRPP and Piezo mRNAs in the optic nerve head prepared from each model (n=3 biologic replicates per time point/severity of glaucoma). The mRNA levels after the elevation in IOP, optic nerve crush, and in glaucomatous degeneration were normalized to the contralateral control eyes (A–D) and control animals with no or early glaucoma (NOE; E–F), and then presented on a log2 scale. Dashed lines represent the mRNA levels of transient receptor potential (TRP) TRPP and Piezo channels in the control groups. Error bar, mean ± SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4502055&req=5

f6: Fold changes in TRPP and Piezo expression levels in three mouse models of optic nerve damage. (A–B) an elevated intraocular pressure (IOP) model, (C–D) an optic nerve crush injury model, and (E–F) glaucomatous DBA/2J mice. Quantitative real-time PCR was performed to assess TRPP and Piezo mRNAs in the optic nerve head prepared from each model (n=3 biologic replicates per time point/severity of glaucoma). The mRNA levels after the elevation in IOP, optic nerve crush, and in glaucomatous degeneration were normalized to the contralateral control eyes (A–D) and control animals with no or early glaucoma (NOE; E–F), and then presented on a log2 scale. Dashed lines represent the mRNA levels of transient receptor potential (TRP) TRPP and Piezo channels in the control groups. Error bar, mean ± SEM.
Mentions: For the TRPP channels, no upregulation was seen in the three mouse models. TRPP1 was downregulated 1 week after short-term elevation in IOP (Figure 6A), and TRPP1 and 2 were downregulated 1 day after the optic nerve crush injury (Figure 6C), but the gene expression changes were not significant. Piezo1 did not show obvious up- or downregulation in any of the three models except 3 days after the crush injury, but Piezo2 showed considerable changes in gene expression. One hour after the elevation of IOP, Piezo2 was downregulated, and the expression level was about 40% of the contralateral control (Figure 6B). In the optic nerve crush model, Piezo2 showed a tendency to be upregulated at most recovery intervals (3 days, 1 week, 3 weeks) although the increases in gene expression were not significant (3 days: 22.43±18.48, 1 week: 7.78±2.35, 3 weeks: 10.39±4.65 compared to the contralateral control; n=3, Figure 6D). The Piezo2 mRNA levels 3 days after the optic nerve crush displayed high variation among the biologic replicates. Piezo2 expression also showed a tendency to be upregulated in moderate and severe glaucoma in the DBA/2J mice, and the relative expression levels were 5.86±3.08 and 7.81±1.92, respectively (n=3). Note that all relative expression levels seen in Figure 6 are presented on a log2 scale to show up- and downregulation of the genes compared to the control groups.

Bottom Line: TRPP2 also showed higher expression in the optic nerve head.Astrocytes in the optic nerve head express multiple putative mechanosensitive channels, in particular the recently identified channels Piezo1 and 2.The expression of putative mechanosensitive channels in these cells may contribute to their responsiveness to traumatic or glaucomatous injury.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, MA.

ABSTRACT

Purpose: To establish whether optic nerve head astrocytes express candidate molecules to sense tissue stretch.

Methods: We used conventional PCR, quantitative PCR, and single-cell reverse transcription PCR (RT-PCR) to assess the expression of various members of the transient receptor potential (TRP) channel family and of the recently characterized mechanosensitive channels Piezo1 and 2 in optic nerve head tissue and in single, isolated astrocytes.

Results: Most TRP subfamilies (TRPC, TRPM, TRPV, TRPA, and TRPP) and Piezo1 and 2 were expressed in the optic nerve head of the mouse. Quantitative real-time PCR analysis showed that TRPC1, TRPM7, TRPV2, TRPP2, and Piezo1 are the dominant isoforms in each subfamily. Single-cell RT-PCR revealed that many TRP isoforms, TRPC1-2, TRPC6, TRPV2, TRPV4, TRPM2, TRPM4, TRPM6-7, TRPP1-2, and Piezo1-2, are expressed in astrocytes of the optic nerve head, and that most astrocytes express TRPC1 and TRPP1-2. Comparisons of the TRPP and Piezo expression levels between different tissue regions showed that Piezo2 expression was higher in the optic nerve head and the optic nerve proper than in the brain and the corpus callosum. TRPP2 also showed higher expression in the optic nerve head.

Conclusions: Astrocytes in the optic nerve head express multiple putative mechanosensitive channels, in particular the recently identified channels Piezo1 and 2. The expression of putative mechanosensitive channels in these cells may contribute to their responsiveness to traumatic or glaucomatous injury.

No MeSH data available.


Related in: MedlinePlus