Biomedical subjects

T Spissinger

Publications and source records attributed to T Spissinger.

4 recordsLinked to original sources

PubMed1995

An extracellular matrix protein of jellyfish homologous to mammalian fibrillins forms different fibrils depending on the life stage of the animal.

A monoclonal antibody generated against the isolated extracellular matrix (ECM) of the medusa Podocoryne carnea M. Sars (Coelenterata, Cnidaria, Hydrozoa) stains a fibrillar component of the Podocoryne ECMs in immunohistochemical preparations. The antigen shows a different staining pattern according to the type of ECMs from the animals life cycle. In ontogeny the epitope first appears after gastrulation in the planula larva as single widely dispersed small fibrils, which later accumulate to form a dense meshwork in the larval ECM. The distribution of the antigen strongly suggests an important role of the molecule to cover the biomechanical needs of the animal. In immunoblots one band with a size of 330 kDa is detectable in the polyp ECM, whereas in the outer ECM of the medusa a 340-kDa band is observed. Both the 330- and the 340-kDa bands appear when probed on the inner ECM of the medusa or on ECMs of the larva. The antibody was used to isolate a cDNA clone from an expression library. The deduced amino acid sequence of this cDNA fragment reveals a molecular structure composed of tandemly repeated epidermal growth factor-like repeats interrupted by a second cystein-rich motif first found in the latent transforming growth factor beta binding protein. Comparison of the sequence to the data bases indicates < 40% identity to human fibrillins. The presence of fibrillin-like beaded microfibrils in the ECM of P. carnea is furthermore demonstrated by electron microscopy after rotary shadowing. Our results demonstrate for the first time the existence of this noncollagenous interstitial ECM protein in invertebrates and suggest that the structure and the function of fibrillin have been conserved during evolution.

Amino Acid Sequence↗

PubMed1995

Type VI collagen beaded microfibrils from bovine cornea depolymerize at acidic pH, and depolymerization and polymerization are not influenced by hyaluronan.

Type VI collagen beaded microfibrils were extracted from bovine cornea or pig cartilage by limited collagenase digestion. Depolymerization of the microfibril, without strong denaturing reagents linke guanidinium hydrochloride or urea under mild acidic conditions, led to single tetramers and multiples of two to three. However, hyaluronidase digestion in accordance with a published method (Kielty et al. J. Cell Biol. 118:979-990, 1992) was unsuccessful in depolymerizing type VI collagen microfibrils. Also, repolymerization into microfibrils by incubation with hyaluronan was not observed. We further found no binding of native type VI collagen microfibrils to a hyaluronan-Sepharose column. Although a recombinant fragment comprising alpha 3(VI) domains N9-N2 showed apparent binding to the column, electron microscopy did not give any indication of binding of either type VI collagen or fragment N9-N2 to hyaluronan. The present findings suggest that the role of hyaluronan in polymerization of type VI collagen has been overestimated in previous work.

Animals↗

PubMed1992

Structure of recombinant N-terminal globule of type VI collagen alpha 3 chain and its binding to heparin and hyaluronan.

A large portion of the N-terminal globule of human collagen VI was prepared from the culture medium of stably transfected human embryonic kidney cell clones. The recombinant product corresponds to sequence positions 1-1586 of the alpha 3 (VI) chain that consists of eight homologous approximately 200 residue motifs (N9 to N2) being similar to the A domain motif of von Willebrand factor. By ultracentrifugation fragment N9-N2 showed a molecular mass of 180 kDa and an asymmetric shape. Elongated structures that consist of eight small globes (diameter approximately 5 nm) were demonstrated by electron microscopy. The data indicate that each A domain motif represents a separate folding unit which are connected to each other by short protease-sensitive peptide segments. Circular dichroism studies demonstrated about 38% alpha helix, 14% beta sheets and 17% beta turns. Fragment N9-N2 showed binding to heparin which could be abolished by moderate salt concentrations. Heparin binding was assigned to domains N9, N6 and N3 which were obtained after partial proteolysis. Domains N7, N5 and N4 lacked affinity for heparin. In addition, N9-N2 showed strong binding to hyaluronan that required exposure to 6 M urea for full dissociation. Ligand binding studies indicated some affinity of N9-N2 for the triple helical region of collagen VI suggesting a role of the N-terminal globule in the self-assembly of microfibrils. No or only little binding was, however, observed to fibril-forming collagens I and III, several basement membrane proteins and other extracellular proteins. Fragment N9-N2 was also an inactive substrate for cell adhesion.

Amino Acid Sequence↗

PubMed1991

Assembly of the surfactant protein SP-A. Deletions in the globular domain interfere with the correct folding of the molecule.

The C-terminal non-collagenous domain of the surfactant glycoprotein SP-A was shown to be essential for its correct folding and assembly, as judged by the secretion of various deletion mutants transiently expressed in COS cells. A deletion mutant coding for this domain was successfully secreted while the expression of the collagenous domain only did not lead to any detectable secretion. Deletion mutants lacking small parts of the non-collagenous domain interfered more or less with the correct folding and assembly of the molecule, thus either reducing or inhibiting the secretion. These data suggest that three prefolded non-collagenous domains register and act as a nucleation center for the folding of the collagenous triple helix which proceeds in a zipper-like fashion towards the N-terminus.

Base Sequence↗