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Retina contains endogenous heparinase activity.
J C Gaal1, L C McIntosh, J V Forrester
1Department of Ophthalmology, University of Aberdeen, Medical School, United Kingdom.
Biochemical and Biophysical Research Communications
|June 15, 1989
Summary
Retinal extracts contain heparinase-like enzymes that may release growth factors for new blood vessel growth. However, a heat-labile inhibitor in retinal homogenates reduces this angiogenic activity.
Area of Science:
- Ophthalmology
- Cell Biology
- Biochemistry
Background:
- Heparin-binding growth factors (HBGF) are crucial for retinal endothelial cell activity.
- These factors are stored in the vascular basement membrane, bound to heparan sulfate, in an inactive state.
- Heparinase enzymes are hypothesized to release angiogenic activity during basement membrane degradation.
Purpose of the Study:
- To investigate the presence and role of heparinase-like activity in retinal mitogenic extracts.
- To understand the contribution of heparinase activity to overall angiogenic potential in the retina.
- To characterize the nature of inhibitors affecting mitogenic activity in retinal homogenates.
Main Methods:
- Analysis of mitogenic saline extracts and non-mitogenic retinal homogenates for heparinase-like activity.
- Comparison of heparinase activity in mitogenic versus non-mitogenic retinal preparations.
- Heat-treatment of retinal homogenate to assess the role of heat-labile inhibitors.
Main Results:
- Mitogenic retinal extracts demonstrated heparinase-like activity, while non-mitogenic homogenates did not.
- Heparinase-like activity was found to account for only a portion of the mitogenic activity in retinal extracts.
- Heat-treatment of retinal homogenate restored 60% of its mitogenic activity but did not induce heparinase activity.
Conclusions:
- Heparinase-like activity is present in mitogenic retinal extracts and may contribute to retinal angiogenesis.
- A heat-labile inhibitor significantly reduces the mitogenic potential of retinal homogenates.
- Further research is needed to fully elucidate the mechanisms of growth factor release and regulation in the retina.