Identification of the active site in the heparin II domain of fibronectin that increases outflow facility in cultured monkey anterior segments.

Donna Peters // Kaufman Lab // Publications // Jan 01 2009

PubMed ID: 18757505

Author(s): Gonzalez JM Jr, Hu Y, Gabelt BT, Kaufman PL, Peters DM. Identification of the active site in the heparin II domain of fibronectin that increases outflow facility in cultured monkey anterior segments. Invest Ophthalmol Vis Sci. 2009 Jan;50(1):235-41. doi: 10.1167/iovs.08-2143. Epub 2008 Aug 29. PMID 18757505

Journal: Investigative Ophthalmology & Visual Science, Volume 50, Issue 1, Jan 2009

PURPOSE To determine the active site in the Heparin II (HepII) domain of fibronectin that regulates outflow facility in cultured anterior segments and disrupts the actin cytoskeleton in transformed human trabecular meshwork (TM-1) cells.

METHODS Outflow facility was determined by two-level, constant-pressure perfusion in cultured anterior segments of rhesus and cynomolgus monkey eyes. One segment from each pair was exchanged with either the HepII domain or an integrin/syndecan binding peptide (IDAPS or PPRARI) from the HepII domain. To assay changes in the actin cytoskeleton, TM-1 cells were incubated for 24 hours with or without the HepII domain, PPRARI, or IDAPS. Changes were monitored with phase and immunofluorescence microscopy.

RESULTS HepII domain (100 microg/mL) and PPRARI (500 microg/mL) increased outflow facility by 31% +/- 13% (n = 9, P < 0.05) and 24% +/- 9% (n = 8, P < 0.05), respectively in cultured anterior segments after an overnight infusion. Perfusion with IDAPS (500 microg/mL) had no effect on outflow facility. In TM-1 cultures, 250 microg/mL of the HepII domain or 4 mg/mL of PPRARI disrupted the assembly of actin filaments. A lower concentration of PPRARI (2 mg/mL) disrupted the actin cytoskeleton when used in combination with a nondisrupting concentration of the HepII domain (30-60 microg/mL). In contrast, IDAPS did not disrupt the actin cytoskeleton under any condition tested.

CONCLUSIONS The active site in the HepII domain that regulates outflow facility in cultured anterior segments and disrupts the actin cytoskeleton in TM-1 cells is the syndecan/integrin binding sequence, PPRARI.