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Attainment of polarity promotes growth factor secretion by retinal pigment epithelial cells: relevance to age-related macular degeneration.

Sonoda S, Sreekumar PG, Kase S, Spee C, Ryan SJ, Kannan R, Hinton DR - Aging (Albany NY) (2009)

Bottom Line: PEDF secretion was about 1000 fold greater than that for VEGF in both polarized and non-polarized cultures.Treatment of non-polarized RPE cultures with bone morphogenetic protein-4 (BMP-4) had no effect on PEDF or VEGF secretion, but resulted in a dose-dependent >2-fold increase in basolateral VEGF secretion (p<0.05) in polarized cultures.Our data show that polarity is an important determinant of the level of PEDF and VEGF secretion in RPE and support the contention that loss of polarity of RPE in AMD results in marked loss of neurotrophic and vascular support for the retina potentially leading to photoreceptor loss and blindness.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA 90089, USA.

ABSTRACT
The antiangiogenic and neurotrophic growth factor, pigment epithelial derived factor (PEDF), and the proangiogenic growth factor, vascular endothelial growth factor-A (VEGF), are released from retinal pigment epithelial (RPE) cells where they play a critical role in the pathogenesis of age-related macular degeneration (AMD). Since RPE polarity may be altered in advanced AMD, we studied the effect of polarization of differentiated, human RPE monolayer cultures on expression and secretion of PEDF and VEGF. Polarized RPE demonstrated apical microvilli, expression of tight junction proteins, apical localization of Na/K- ATPase, and high transepithelial resistance (490 +/- 17 Omega x cm(2)). PEDF secretion was about 1000 fold greater than that for VEGF in both polarized and non-polarized cultures. Polarization of the RPE monolayer increased PEDF secretion, which was predominantly apical, by 34 fold (p<0.02) and VEGF secretion, which was predominantly basolateral, by 5.7 fold (p<0.02). Treatment of non-polarized RPE cultures with bone morphogenetic protein-4 (BMP-4) had no effect on PEDF or VEGF secretion, but resulted in a dose-dependent >2-fold increase in basolateral VEGF secretion (p<0.05) in polarized cultures. Our data show that polarity is an important determinant of the level of PEDF and VEGF secretion in RPE and support the contention that loss of polarity of RPE in AMD results in marked loss of neurotrophic and vascular support for the retina potentially leading to photoreceptor loss and blindness.

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Distribution of PEDF in apical, central and basal regions in nonpolarized and polarized RPE cells by confocal microscopy.   Staining for PEDF                                        is more intense in polarized RPE as compared to nonpolarized RPE.  The apical                                        region shows much higher PEDF expression in polarized cells.
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Figure 4: Distribution of PEDF in apical, central and basal regions in nonpolarized and polarized RPE cells by confocal microscopy. Staining for PEDF is more intense in polarized RPE as compared to nonpolarized RPE. The apical region shows much higher PEDF expression in polarized cells.

Mentions: Figure 4 shows the confocal immunofluorescent staining for PEDF in nonpolarized and polarized RPE cells. The intensity of PEDF staining was found to be much higher for polarized RPE as compared to nonpolarized RPE. Further, examination of subcellular distribution in the polarized RPE revealed a progressive increase in PEDF expression from basal to central to apical regions, with maximal expression seen in the apical region. This pre-dominant staining in the apical region is consistent with a significantly higher apical secretion shown in Figure 3.


Attainment of polarity promotes growth factor secretion by retinal pigment epithelial cells: relevance to age-related macular degeneration.

Sonoda S, Sreekumar PG, Kase S, Spee C, Ryan SJ, Kannan R, Hinton DR - Aging (Albany NY) (2009)

Distribution of PEDF in apical, central and basal regions in nonpolarized and polarized RPE cells by confocal microscopy.   Staining for PEDF                                        is more intense in polarized RPE as compared to nonpolarized RPE.  The apical                                        region shows much higher PEDF expression in polarized cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2837203&req=5

Figure 4: Distribution of PEDF in apical, central and basal regions in nonpolarized and polarized RPE cells by confocal microscopy. Staining for PEDF is more intense in polarized RPE as compared to nonpolarized RPE. The apical region shows much higher PEDF expression in polarized cells.
Mentions: Figure 4 shows the confocal immunofluorescent staining for PEDF in nonpolarized and polarized RPE cells. The intensity of PEDF staining was found to be much higher for polarized RPE as compared to nonpolarized RPE. Further, examination of subcellular distribution in the polarized RPE revealed a progressive increase in PEDF expression from basal to central to apical regions, with maximal expression seen in the apical region. This pre-dominant staining in the apical region is consistent with a significantly higher apical secretion shown in Figure 3.

Bottom Line: PEDF secretion was about 1000 fold greater than that for VEGF in both polarized and non-polarized cultures.Treatment of non-polarized RPE cultures with bone morphogenetic protein-4 (BMP-4) had no effect on PEDF or VEGF secretion, but resulted in a dose-dependent >2-fold increase in basolateral VEGF secretion (p<0.05) in polarized cultures.Our data show that polarity is an important determinant of the level of PEDF and VEGF secretion in RPE and support the contention that loss of polarity of RPE in AMD results in marked loss of neurotrophic and vascular support for the retina potentially leading to photoreceptor loss and blindness.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Keck School of Medicine of University of Southern California, Los Angeles, CA 90089, USA.

ABSTRACT
The antiangiogenic and neurotrophic growth factor, pigment epithelial derived factor (PEDF), and the proangiogenic growth factor, vascular endothelial growth factor-A (VEGF), are released from retinal pigment epithelial (RPE) cells where they play a critical role in the pathogenesis of age-related macular degeneration (AMD). Since RPE polarity may be altered in advanced AMD, we studied the effect of polarization of differentiated, human RPE monolayer cultures on expression and secretion of PEDF and VEGF. Polarized RPE demonstrated apical microvilli, expression of tight junction proteins, apical localization of Na/K- ATPase, and high transepithelial resistance (490 +/- 17 Omega x cm(2)). PEDF secretion was about 1000 fold greater than that for VEGF in both polarized and non-polarized cultures. Polarization of the RPE monolayer increased PEDF secretion, which was predominantly apical, by 34 fold (p<0.02) and VEGF secretion, which was predominantly basolateral, by 5.7 fold (p<0.02). Treatment of non-polarized RPE cultures with bone morphogenetic protein-4 (BMP-4) had no effect on PEDF or VEGF secretion, but resulted in a dose-dependent >2-fold increase in basolateral VEGF secretion (p<0.05) in polarized cultures. Our data show that polarity is an important determinant of the level of PEDF and VEGF secretion in RPE and support the contention that loss of polarity of RPE in AMD results in marked loss of neurotrophic and vascular support for the retina potentially leading to photoreceptor loss and blindness.

Show MeSH
Related in: MedlinePlus