Chondroitin sulfate and chondroitin/keratan sulfate proteoglycans of nervous tissue: developmental changes of neurocan and phosphacan.
We have studied developmental changes in the structure and concentration of the hyaluronic acid-binding proteoglycan, neurocan, and of phosphacan, another major chondroitin sulfate proteoglycan of nervous tissue that represents the extracellular domain of a receptor-type protein tyrosine phosphatase. A new monoclonal antibody (designated 1F6), which recognizes an epitope in the N-terminal portion of neurocan, has been used for the isolation of proteolytic processing fragments that occur together with link protein in a complex with hyaluronic acid. Both link protein and two of the neurocan fragments were identified by amino acid sequencing. The N-terminal fragments of neurocan are also recognized by monoclonal antibodies (5C4, 8A4, and 3B1) to epitopes in the G1 and G2 domains of aggrecan and/or in the hyaluronic acid-binding domain of link protein. The presence in brain of these N-terminal fragments is consistent with the developmentally regulated appearance of the C-terminal half of neurocan, which we described previously. We have also used a slot-blot radioimmunoassay to determine the concentrations of neurocan and phosphacan in developing brain. The levels of both proteoglycans increased rapidly during early brain development, but whereas neurocan reached a peak at approximately postnatal day 4 and then declined to below embryonic levels in adult brain, the concentration of phosphacan remained essentially unchanged after postnatal day 12. Keratan sulfate on phosphacan-KS (a glycoform that contains both chondroitin sulfate and keratan sulfate chains) was not detectable until just before birth, and its peak concentration (at 3 weeks postnatal) was reached approximately 1 week later than that of the phosphacan core protein. Immunocytochemical studies using monoclonal antibodies to keratan sulfate (3H1 and 5D4) together with specific glycosidases (endo-beta-galactosidase, keratanase, and keratanase II) also showed that with the exception of some very localized areas, keratan sulfate is generally not present in the embryonic rat CNS.
Meyer-Puttlitz
B
B
Department of Pharmacology, State University of New York, Health Science Center, Brooklyn 11203, USA.
Milev
P
P
Junker
E
E
Zimmer
I
I
Margolis
R U
RU
Margolis
R K
RK
D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D002807:Chondroitin / Q000378:metabolism; D011508:Chondroitin Sulfate Proteoglycans / Q000378:metabolism*; D002809:Chondroitin Sulfates / Q000378:metabolism; D007150:Immunohistochemistry; D007632:Keratan Sulfate / Q000378:metabolism; D037181:Lectins, C-Type; D051379:Mice; D008807:Mice, Inbred BALB C; D009417:Nerve Tissue / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D058580:Neurocan; D011509:Proteoglycans / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5
D011508:Chondroitin Sulfate Proteoglycans; D037181:Lectins, C-Type; D009419:Nerve Tissue Proteins; D058580:Neurocan; D011509:Proteoglycans; C076817:NCAN protein, human; D002807:Chondroitin; D002809:Chondroitin Sulfates; D007632:Keratan Sulfate; C516895:PTPRZ1 protein, human; C516896:Ptprz1 protein, mouse; C516897:Ptprz1 protein, rat; D054633:Receptor-Like Protein Tyrosine Phosphatases, Class 5