Studies on type I collagen in skin fibroblasts cultured from twins with lethal osteogenesis imperfecta.
Studies on type I procollagen produced by skin fibroblasts cultured from twins with lethal type II of osteogenesis imperfecta (OI) showed that biosynthesis of collagen (measured by L-[5-(3)H]proline incorporation into proteins susceptible to the action of bacterial collagenase) was slightly increased as compared to the control healthy infant. SDS/PAGE showed that the fibroblasts synthesized and secreted only normal type I procollagen. Electrophoretic analysis of collagen chains and CNBr peptides showed the same pattern of electrophoretic migration as in the controls. The lack of posttranslational overmodification of the collagen molecule suggested a molecular defect near the amino terminus of the collagen helix. Digestion of OI type I collagen with trypsin at 30 degrees C for 5 min generated a shorter than normal alpha2 chain which melted at 36 degrees C. Direct sequencing of an asymmetric PCR product revealed a heterozygous single nucleotide change C-->G causing a substitution of histidine by aspartic acid in the alpha2 chain at position 92. Pericellular processing of type I procollagen by the twin's fibroblasts yielded a later appearance of the intermediate pC-alpha1(I) form as compared with control cells.
Galicka
Anna
A
Department of Medical Chemistry, Medical Academy of Białystok, 15-230 Białystok 8, Poland. angajko@amb.ac.bialystok.pl
Wołczyński
Sławomir
S
Gindzieński
Andrzej
A
D001224:Aspartic Acid / Q000235:genetics; D001483:Base Sequence; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D003488:Cyanogen Bromide; D018076:DNA, Complementary / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000378:metabolism*; D006639:Histidine / Q000235:genetics; D006801:Humans; D007223:Infant; D010013:Osteogenesis Imperfecta / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D010446:Peptide Fragments / Q000032:analysis; D017354:Point Mutation; D011347:Procollagen / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D012867:Skin / Q000166:cytology / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D014427:Twins
D024042:Collagen Type I; D018076:DNA, Complementary; D010446:Peptide Fragments; D011347:Procollagen; D001224:Aspartic Acid; D006639:Histidine; D011392:Proline; D014357:Trypsin; D003488:Cyanogen Bromide