title: Sulfated proteoglycans and sulfated proteins in guinea pig megakaryocytes and platelets in vivo. Relevance to megakaryocyte maturation and platelet activation.
abstract: This study has examined changes in proteoglycan synthesis during megakaryocyte maturation in vivo. Guinea pigs were injected with Na235SO4, and megakaryocytes and platelets were isolated from 3 h to 5 days later. The proteoglycans and other sulfated molecules in both cells were characterized at each time point by gel filtration, ion-exchange chromatography, gel electrophoresis, and chemical and enzymatic digestions. Two populations of chondroitin 6-sulfate proteoglycans were found by DEAE-Sephacel chromatography. The major fraction was eluted with 4 M guanidine hydrochloride and the minor fraction with 4 M guanidine HCl, 2% Triton X-100. The Kav of the major proteoglycan peak in the platelets at 1 day after injection was 0.18-0.20 on Sepharose CL-6B and decreased gradually to 0.12 by 3 days, when proteoglycan radioactivity per cell was maximal. The peak for megakaryocyte proteoglycans at 3 h was broad, with Kav = 0.1-0.2. The appearance of different portions of the proteoglycan peak in platelets coincided with their disappearance from megakaryocytes. Proteoglycan size was a function of glycosaminoglycan chain length. The proteoglycans eluted with Triton X-100 from DEAE-Sephacel (Kav = 0.04-0.07 on Sepharose CL-6B) were not labeled in platelets until 2 days after injection. Our data suggest that megakaryocytes synthesize different-sized chondroitin sulfate proteoglycans at different stages of development. The proteoglycans of the major fraction were released from platelets in response to thrombin, and a small amount was released by ADP. The proteoglycans of the Triton X-100 eluate were not released by thrombin or ADP. About 20% of the sulfate radioactivity was incorporated into molecules that appear to be sulfated proteins and were not released by thrombin or ADP.
authors.affiliation: Thrombosis Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
authors.forename: B P
authors.initials: BP
authors.lastname: Schick
authors.forename: C J
authors.initials: CJ
authors.lastname: Walsh
authors.forename: T
authors.initials: T
authors.lastname: Jenkins-West
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D001792:Blood Platelets / Q000032:analysis* / Q000166:cytology; D001798:Blood Proteins / Q000032:analysis*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D005470:Fluorometry; D006025:Glycosaminoglycans / Q000032:analysis; D006168:Guinea Pigs; D006801:Humans; D008533:Megakaryocytes / Q000032:analysis* / Q000166:cytology; D008970:Molecular Weight; D010974:Platelet Aggregation; D011509:Proteoglycans / Q000097:blood*; D013431:Sulfates / Q000378:metabolism; D013917:Thrombin / Q000378:metabolism
chemical_list: D001798:Blood Proteins; D006025:Glycosaminoglycans; D011509:Proteoglycans; D013431:Sulfates; C012036:sodium sulfate; D000244:Adenosine Diphosphate; D013917:Thrombin