[New collagenous proteins: FACIT collagens, transmembrane collagens and multiplexins]. / Nowe bialka kolagenowe: kolageny FACIT, transblonowe i multipleksyny.

Collagens are the main components of the extracellular matrix and they constitute about 30% of total body protein. Each collagen molecule consists of three polypeptide chains that intertwine in one or more places into triple helical domains, a very rare structure in other proteins. Nineteen collagen types have been described to date and these forming banded fibrils are the most abundant. In the last decade new collagenous proteins were discovered that have been classified into three distinct groups: fibril-associated collagens with interrupted triple helices (FACITs), transmembrane collagens and multiplexins. FACITs appear to connect collagen fibrils to other matrix components or cells. Transmembrane collagens have intracellular domains and they participate in cell adhesion and probably in signal transduction. Multiplexins are situated mainly in basement membranes and contain sequences, which demonstrate features of angiogenesis inhibitors reducing the growth of neoplasmatic tumours.

Pre-eclampsia-associated differential expression of proteoglycans in the umbilical cord arteries.

OBJECTIVE: The role of proteoglycans (PGs) of the umbilical cord arteries (UCAs) in the pathomechanism of pre-eclampsia is not known. Therefore we decided to compare the PGs of normal (control) UCAs and those of newborns delivered by mothers with pre-eclampsia. METHODS: PGs were extracted in dissociative conditions, purified by Q-Sepharose anion exchange chromatography and lyophilized. They were analyzed by gel filtration and SDS-PAGE before and after treatment with chondroitinase ABC. RESULTS: It was found that the PG preparation from pre-eclamptic UCAs had a higher amount of sulphated glycosaminoglycans (in relation to protein) than in the case of control UCAs. The predominant PG fraction included small PGs with core proteins of 45 and 47 kD, immunologically related to biglycan (45 kD) and decorin (45 and 47 kD). The expression of decorin core proteins was increased and that of biglycan slightly decreased in pre-eclamptic UCAs. Some other putative small PG core proteins (56, 53, 49, 42, 38 and 34 kD) were also found. They were present in higher amounts in pre-eclamptic UCAs. Larger PGs (core proteins of 99-110 and >150 kD), were detected in lower amounts, both in control and particularly in pre-eclamptic material. CONCLUSION: Pre-eclampsia is associated with alterations in PG composition of the UCAs. They may affect the mechanical properties of this organ and disturb fetal blood circulation.

Proteoglycans of human umbilical cord arteries.

Proteoglycans (PGs) were dissociatively extracted from human umbilical cord arteries (UCAs) with 4 M guanidine hydrochloride containing Triton X-100 and protease inhibitors, purified by Q-Sepharose anion exchange chromatography and lyophilized. They were analysed by gel filtration, SDS/PAGE and agarose gel electrophoresis before and after treatment with chondroitinase ABC. It was found that the PG preparation was especially enriched in chondroitin/dermatan sulphate PGs. The predominant PG fraction included small PGs that emerged from Sepharose CL-2B with Kav = 0.74. Their molecular mass, estimated by SDS/PAGE, was 160-200 kDa and 90-150 kDa, i.e. it was typical for biglycan and decorin, respectively. Treatment with chondroitinase ABC yielded the core proteins of 45 and 47 kDa, characteristic for both small PGs. Remarkable amounts of the 45 kDa protein were detected in non-treated PG samples, suggesting the presence of free core proteins of biglycan and decorin. Large PGs were present in lower amounts. In intact form they were eluted from Sepharose CL-2B with Kav = 0.17 and 0.43. Digestion with chondroitinase ABC yielded the core proteins with a molecular mass within the range of 180-360 kDa but predominant were the bands of 200, 250 and 360 kDa. The large PGs probably represent various forms of versican or perlecan bearing chondroitin sulphate chains.

[Alterations in the content of collagenous constituents of amniotic fluid in the course of EPH-gestosis]. / Zmiany w zawartosci skladników kolagenowych plynu owodniowego w przebiegu gestozy-EPH.

OBJECTIVES: EPH-gestosis may cause placental insufficiency and affect the metabolism of placenta and fetus. Various metabolites of amniotic fluid may reflect the fetal metabolism. DESIGN: It was decided to compare the content and some biochemical features of hydroxyproline-containing collagenous constituents in the amniotic fluid derived from normal gestations and gestations affected by EPH-gestosis. MATERIALS AND METHODS: Amniotic fluid was taken during labour (full-term gestations) by amniocentesis from 10 healthy women (control group) and 10 women with EPH-gestosis. UV-absorption spectra, protein and hydroxyproline were measured in non-dialyzed and dialyzed amniotic fluid. Hydroxyproline-containing collagenous constituents of amniotic fluid were chromatographed on Sephadex G-200. RESULTS: Statistical differences in concentrations of total and non-dialyzable hydroxyproline between normal and gestotic amniotic fluid were not found. In contrast to that, gestotic amniotic fluid contains more dialyzable hydroxyproline (6.2 mg/ml) than normal fluid (4.5 mg/ml; p < 0.05). Molecular sieving on Sephadex G-200 shows that this difference is due to higher content of low molecular collagen degradation products. CONCLUSION: Amniotic fluid, derived from pregnancies complicated by EPH-gestosis, contains higher amount of low molecular collagen degradation products than normal amniotic fluid. It is probably the result of more intensive degradation of fetal and placental collagen.

Collagenous constituents of amniotic fluid.

The amniotic fluid (AF) was fractionated by dialysis, gel filtration and SDS/PAGE, and submitted to the assay of collagenous constituents. The collagenous character of peptides and proteins of amniotic fluid was confirmed by hydroxyproline (Hyp) assay and treatment with bacterial collagenase followed by electrophoresis and gel filtration of the digestion products. It was found that AF contains collagen degradation products but the classical method of Hyp determination described by Woessner (Arch. Biochem. Biophys., 1961, 93, 440-447) gives overestimated values due to the interference with other AF components. Fractionation of AF on Sephadex G-100 column allowed to remove the interfering material and to estimate the actual Hyp content which equals to approx. 6.2 microg/ml. About 70% of Hyp was found in low molecular dialyzable products and the rest (about 30%) appears to be a constituent of nondialyzable collagenous polypeptides of the molecular mass of about 7.9-26.3 kDa. It is suggested that such collagenous polypeptides may be the products of proteolytic conversion of collagen precursor (procollagen) into the monomeric form of this protein. No high molecular forms of collagen, corresponding to alpha-subunits, were found.

[Collagen degradation products in amniotic fluid]. / Produkty degradacji kolagenu obecne w plynie owodniowym.

It was found that amniotic fluid (38-42 Hbd) contains hydroxyproline in concentration about 10 micrograms/ml. Gel filtration and dialysis demonstrated that most of hydroxyproline exists in a form of low molecular weight products. Furthermore, it was found that amniotic fluid contains a protein which eluates during gel filtration in void volume of the column. It gives a positive reaction for hydroxyproline but the absorption spectrum of such product is not characteristic for this amino acid. Furthermore, it is not digested by bacterial collagenase. It allows to conclude that amniotic fluid (38-42 Hbd) does not contain collagenous proteins. Only low molecular weight degradation products were found. Only part of them is susceptible on the action of bacterial collagenase.