Hyaluronic acid production and hyaluronidase activity in the newt iris during lens regeneration

Journal Article · Tue Sep 01 04:00:00 EDT 1987 · Exp. Cell Res.; (United States)

DOI:https://doi.org/10.1016/0014-4827(87)90104-2· OSTI ID:5856935

Kulyk, W M; Zalik, S E; Dimitrov, E

The process of lens regeneration in newts involves the dedifferentiation of pigmented iris epithelial cells and their subsequent conversion into lens fibers. In vivo this cell-type conversion is restricted to the dorsal region of the iris. We have examined the patterns of hyaluronate accumulation and endogenous hyaluronidase activity in the newt iris during the course of lens regeneration in vivo. Accumulation of newly synthesized hyaluronate was estimated from the uptake of (/sup 3/H)glucosamine into cetylpyridinium chloride-precipitable material that was sensitive to Streptomyces hyaluronidase. Endogenous hyaluronidase activity was determined from the quantity of reducing N-acetylhexosamine released upon incubation of iris tissue extract with exogenous hyaluronate substrate. We found that incorporation of label into hyaluronate was consistently higher in the regeneration-activated irises of lentectomized eyes than in control irises from sham-operated eyes. Hyaluronate labeling was higher in the dorsal (lens-forming) region of the iris than in ventral (non-lens-forming) iris tissue during the regeneration process. Label accumulation into hyaluronate was maximum between 10 and 15 days after lentectomy, the period of most pronounced dedifferentiation in the dorsal iris epithelium. Both normal and regenerating irises demonstrated a high level of endogenous hyaluronidase activity with a pH optimum of 3.5-4.0. Hyaluronidase activity was 1.7 to 2 times higher in dorsal iris tissue than in ventral irises both prior to lentectomy and throughout the regeneration process. We suggest that enhanced hyaluronate accumulation may facilitate the dedifferentiation of iris epithelial cells in the dorsal iris and prevent precocious withdrawal from the cell cycle. The high level of hyaluronidase activity in the dorsal iris may promote the turnover and remodeling of extracellular matrix components required for cell-type conversion.

• Research Organization: Univ. of Alberta, Edmonton
• OSTI ID: 5856935
• Journal Information: Exp. Cell Res.; (United States), Journal Name: Exp. Cell Res.; (United States) Vol. 172:1; ISSN ECREA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINES
AMPHIBIANS
ANIMAL TISSUES
ANIMALS
AQUATIC ORGANISMS
BIOLOGICAL RECOVERY
BIOLOGICAL REGENERATION
BIOSYNTHESIS
BODY
BODY AREAS
CARBOHYDRATES
CELL DIFFERENTIATION
CRYSTALLINE LENS
ENZYME ACTIVITY
ENZYMES
EPITHELIUM
EYES
FACE
GLUCOSAMINE
GLYCOSYL HYDROLASES
HEAD
HEXOSAMINES
HEXOSES
HYALURONIC ACID
HYALURONIDASE
HYDROLASES
IN VIVO
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MONOSACCHARIDES
MUCOPOLYSACCHARIDES
O-GLYCOSYL HYDROLASES
ORGANIC COMPOUNDS
ORGANS
POLYSACCHARIDES
RECOVERY
SACCHARIDES
SALAMANDERS
SENSE ORGANS
SYNTHESIS
TISSUES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES