Proteoglycan expression by human trabecular meshworks.
OBJECTIVE
Proteoglycans may serve important roles in trabecular meshwork structure or function. Detailed molecular characterization and identification of specific trabecular proteoglycan core proteins has been limited.


METHODS
Radiolabeled proteoglycans were extracted from cultured human trabecular meshworks and subjected to ion exchange and molecular sieve chromatography. Peaks were subjected to glycosaminoglycan content analysis. Reverse transcription with polymerase chain reaction was used to identify trabecular mRNAs of several common proteoglycan core proteins. Western immunoblots of trabecular extracts were also utilized to identify these proteoglycan core proteins.


RESULTS
The proteoglycans elute from ion exchange columns at high salt and molecular sieve column profiles, and they exhibit broad peaks typical of the proteoglycan microheterogeneity seen in other tissues. The four common glycosaminoglycan side-chains were identified on these proteoglycans. Trabecular cells in organ or cell culture contain mRNAs coding for decorin, biglycan, versican, perlecan and a basement membrane glycoprotein, SPARC. Syndecan-1 transcripts were present at very low levels, while aggrecan transcripts were not detectable. Decorin, biglycan, versican and perlecan core proteins were also identified by immunoblots of trabecular cell extracts.


CONCLUSIONS
Several common proteoglycans are expressed by trabecular cells in organ explant or cell culture. Their general characteristics are not unlike those found in other tissues. These proteoglycans may serve important functions in the trabecular outflow pathway.
Wirtz
M K
MK
Department of Ophthalmology, Casey Eye Institute, Oregon Health Sciences University, Portland 97201, USA.
Bradley
J M
JM
Xu
H
H
Domreis
J
J
Nobis
C A
CA
Truesdale
A T
AT
Samples
J R
JR
Van Buskirk
E M
EM
Acott
T S
TS
D053674:Aggrecans; D015153:Blotting, Western; D002478:Cells, Cultured; D002845:Chromatography; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins / Q000235:genetics; D006025:Glycosaminoglycans / Q000032:analysis; D006801:Humans; D037181:Lectins, C-Type; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D016133:Polymerase Chain Reaction; D011509:Proteoglycans / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger; D014129:Trabecular Meshwork / Q000166:cytology / Q000378:metabolism*
D053674:Aggrecans; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D006025:Glycosaminoglycans; D037181:Lectins, C-Type; D011509:Proteoglycans; D012333:RNA, Messenger