Hyaluronan dynamics during retinal development.

We have already shown the regulated expressions of hyaluronan binding molecules including versican, SPACR, and SPACRCAN, during retinal development. Here we analyzed the profiles of hyaluronan during these periods. Hyaluronan and hyaluronan synthase (HAS) expressions in chicken retinas at different ages were assessed by slot blot and real-time PCR, respectively. The molecular size of hyaluronan was determined using a Superose-6 column, and histochemistry was used to localize hyaluronan expression. Hyaluronan degradation activity was measured after adding hyaluronan to retinal extracts. In the embryonic retina, hyaluronan was mainly present in the inner plexiform and photoreceptor layers. Expression in the inner plexiform layer decreased with development and aging while expression in the photoreceptor layer remained constant. The molecular size of hyaluronan decreased from embryonic day 12 (E12) to postnatal day 1 (P1) with increasing retinal hyaluronan degradation activity. In adult retinas, hyaluronan was only present in the photoreceptor layer, and its molecular size was the highest. HAS-2 and HAS-3 expressions increased from E15 to P1, but both were reduced in adulthood. Thus hyaluronan was specifically detected where versican, SPACR, and SPACRCAN were previously demonstrated, and the synthesis and degradation of hyaluronan are regulated. Hyaluronan together with versican, SPACR, and SPACRCAN are closely related during retinal development, and may be important for retinal physiology.