A novel hatching enzyme from starfish Asterias amurensis: purification, characterization, and cleavage specificity

Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases in Echinoderms: Structure and Possible Functions

Echinoderms are one of the most ancient groups of invertebrates. The study of their genomes has made it possible to conclude that these animals have a wide variety of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). The phylogenetic analysis shows that the MMPs and TIMPs underwent repeated duplication and active divergence after the separation of Ambulacraria (Echinodermata+Hemichordata) from the Chordata. In this regard the homology of the proteinases and their inhibitors between these groups of animals cannot be established. However, the MMPs of echinoderms and vertebrates have a similar domain structure. Echinoderm proteinases can be structurally divided into three groups-archetypal MMPs, matrilysins, and furin-activatable MMPs. Gelatinases homologous to those of vertebrates were not found in genomes of studied species and are probably absent in echinoderms. The MMPs of echinoderms possess lytic activity toward collagen type I and gelatin and play an important role in the mechanisms of development, asexual reproduction and regeneration. Echinoderms have a large number of genes encoding TIMPs and TIMP-like proteins. TIMPs of these animals, with a few exceptions, have a structure typical for this class of proteins. They contain an NTR domain and 10-12 conservatively located cysteine residues. Repeated duplication and divergence of TIMP genes of echinoderms was probably associated with an increase in the functional importance of the proteins encoded by them in the physiology of the animals.

Possible Mechanisms of Hatching from Egg Capsules in the Gastropods Crepipatella dilatata and Crepipatella peruviana, Species with Different Modes of Early Development

Many invertebrates enclose their embryos within egg capsules, from which the offspring hatch. In marine gastropods that brood their egg capsules, hatching could involve radular activity by the mother or by unhatched stages, increased osmotic concentration of the intracapsular fluid, or production of hatching enzymes. The present research sought to determine whether mechanical action by the brooding female or by the encapsulated embryos was involved in the hatching for two sympatric and closely related species of calyptraeid: Crepipatella dilatata, which exhibits direct development without free-living larvae, and Crepipatella peruviana, which releases free-living veliger larvae. We also considered the role that enzymatic action or osmotic changes in the intracapsular fluid might play in hatching. Using scanning electron micrograph analyses, we found no evidence that the well-developed, pre-hatching juvenile radula of C. dilatata played any role in the hatching process and that the radula of C. peruviana did not even develop until long after hatching; so there was no evidence of radular activity involved in the hatching of either species. For C. peruviana, the intracapsular fluid osmolality was always higher than that of the surrounding seawater, suggesting that there is a strong natural water inflow during development. Moreover, when egg capsules of C. peruviana were exposed to lower ambient salinities, the substantial entry of water correlated well with high percentages of hatching, particularly for egg capsules containing advanced veligers, suggesting that an osmotic mechanism may be involved in the hatching process of this species. In contrast, hatching in C. dilatata appeared to be enzymatically mediated.

Characterization of a novel hatching enzyme purified from starfish Asterina pectinifera

Hatching enzyme is a protease which can degrade the membrane of egg. In this study, a hatching enzyme was purified from starfish (Asterina pectinifera) with 6.34 fold of purification rate, 5.04 % of yield, and 73.87 U/mg of specific activity. The molecular weight of starfish hatching enzyme was 86 kDa, which was reduced to 62 kDa after removal of N-linked oligosaccharides. The optimal pH and temperature of the hatching enzyme activity were pH 7.0 and 40 °C, respectively, while those of stability were pH 8 and 20 °C. The kinetic parameters, V_max, K_m, K_cat and K_cat/K_m values were 0.197 U/ml, 0.289 mg/ml, 112.57 s⁻¹, and 389.52 ml/mg s, respectively. Zn²⁺ increased the enzyme activity by 167.28 %, while EDTA, TPCK, TGCK, leupeptin, PMSF, and TLCK decreased. In addition, Ca²⁺, Mg²⁺, and Cu²⁺ did not affect the enzyme activity. The starfish hatching enzyme activity pretreated with EDTA was recovered by Zn²⁺. Therefore, the starfish hatching enzyme was classified as a serine-zinc protease.

The application of the starfish hatching enzyme for the improvement of scar and keloid based on the fibroblast-populated collagen lattice

Various bioactivities of the starfish hatching enzyme (HE) including collagen gel contraction, MMPs activity, hydroxyproline release, and gene regulation based on the fibroblast-populated collagen lattice (FPCL) in three-dimensional medium were investigated for the improvement of scar and keloid. The starfish HE significantly inhibited the collagen gel contraction over 2 days of culture. MMP-2 and MMP-9 activities were also identified by gelatin zymography and RT-PCR products with both HE and collagenase treatments, which resulted in the high amount of hydroxyproline release. The HE treatment on the FPCL significantly inhibited the fibroblast proliferation at 3 days of culture. The LPS-induced NO level and iNOS mRNA expression at low concentrations of HE presented a certain ability to inflammatory response. The COX-2 mRNA from the FPCL indicated no significant inflammation-mediated activity at 5 μg/mL of HE, whereas the cytokines of TNF-α and IL-1β were significantly higher than those of the control. Hence, the starfish hatching enzyme can regulate the fibroblast-populated collagen gel conditions by the contraction, MMP production, inflammatory gene expression, etc. Therefore, the starfish HE could be a potential cosmeceutical to heal the scar and keloid tissue.