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In situ localization of basic fibroblast growth factor protein and mRNA in the retina
M Ohsato1, H Hayashi, K Oshima
1Department of Ophthalmology, School of Medicine, Fukuoka University, Japan.
Abstract:
Basic fibroblast growth factor (FGF) protein has been recognized as a potent factor for angiogenesis and as a mitogen. The sites of basic FGF in the mammalian retina have varied from report to report. On the other hand, only the inner segments of the photoreceptor cells have been reported to synthesized basic FGF as revealed by the presence of mRNA for basic FGF by in situ hybridization. To define the sites of basic FGF and its mRNA in the human retina, we immunohistochemically localized basic FGF protein and mRNA for basic FGF by in situ hybridization in normal human retinas. Basic FGF protein was found in the ganglion cell layer, the inner and outer nuclear layers, and the basement membranes of Müller cells (the inner limiting membrane), blood vessels, and the retinal pigment epithelium (Bruch's membrane). The mRNA for basic FGF was found in the cells of the ganglion cell layer, the inner nuclear layer, and the outer nuclear layer, and the inner segments of the photoreceptor cells. These findings suggest that basic FGF in the human retina functions in both an autocrine as well as a paracrine fashion.
Insights
Basic fibroblast growth factor (FGF) protein and its mRNA are found throughout the human retina, including photoreceptor cells. This suggests FGF plays autocrine and paracrine roles in retinal function.
Area of Science:
- Ophthalmology
- Cell Biology
- Molecular Biology
Background:
- Basic fibroblast growth factor (FGF) is a known mitogen and factor for angiogenesis.
- Previous studies reported varying locations of basic FGF in mammalian retinas.
- Only inner photoreceptor segments were previously identified as synthesizing basic FGF mRNA.
Purpose of the Study:
- To precisely define the locations of basic FGF protein and its mRNA in the human retina.
- To clarify the cellular distribution of basic FGF and its precursor in retinal tissues.
Main Methods:
- Immunohistochemistry was used to localize basic FGF protein.
- In situ hybridization was employed to detect basic FGF mRNA.
- Normal human retinas were analyzed using these techniques.
Main Results:
- Basic FGF protein was detected in the ganglion cell layer, inner and outer nuclear layers, Müller cell basement membranes, blood vessels, and retinal pigment epithelium (Bruch's membrane).
- Basic FGF mRNA was identified in the ganglion cell layer, inner and outer nuclear layers, and inner photoreceptor segments.
- Co-localization of protein and mRNA suggests localized synthesis and function.
Conclusions:
- Basic fibroblast growth factor (FGF) is present in multiple cell layers and structures within the human retina.
- The distribution of basic FGF protein and mRNA indicates both autocrine and paracrine functions in the human retina.
- These findings provide a more comprehensive understanding of FGF's role in retinal biology.