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Identification and characterization of a serpin with differential expression during the life cycle of the sea lamprey
1Division of Cardiovascular Research, Hospital for Sick Children, Toronto, Canada.
Abstract:
We have cloned a member of the serine proteinase inhibitor gene superfamily from the sea lamprey, Petromyzon marinus. The predicted translation product contains a putative signal peptide and mRNA expression is localized mainly to the liver. Northern blot analysis indicates that the mRNA increases in the larvae and peaks in late larval life. At the onset of metamorphosis there is a approximately 10-fold drop after which it remains low. These changes correspond with levels of circulating thyroid hormone suggesting that this serpin is involved in or regulated by molecular signals that induce metamorphosis in the lamprey. Use of alignments and structural information from other serpins indicates that the lamprey serpin has the potential to be inhibitory. In addition the lamprey serpin contains methionine and serine at the P1 and P1' positions, respectively. Appropriate residues at positions important in allowing the insertion of strand s4A into beta-sheet A that occurs upon cleavage in inhibitory serpins are also found in the lamprey serpin.
Insights
Researchers identified a new sea lamprey serpin (serine proteinase inhibitor) gene. Its expression changes during development, correlating with thyroid hormone levels and metamorphosis, suggesting a regulatory role.
Area of Science:
- * Molecular Biology
- * Evolutionary Biology
- * Developmental Biology
Background:
- * The serine proteinase inhibitor (serpin) superfamily plays crucial roles in regulating proteolytic cascades.
- * Understanding serpin function in diverse species like the sea lamprey (Petromyzon marinus) can provide insights into conserved biological processes.
- * The sea lamprey, an ancient vertebrate lineage, offers a unique model for studying evolutionary adaptations.
Purpose of the Study:
- * To clone and characterize a novel serpin gene from the sea lamprey.
- * To investigate the expression patterns of this serpin during larval development and metamorphosis.
- * To assess the potential inhibitory function of the sea lamprey serpin based on structural and sequence analysis.
Main Methods:
- * Gene cloning techniques were employed to isolate the sea lamprey serpin.
- * Northern blot analysis was used to determine mRNA expression levels.
- * Sequence alignments and structural comparisons with known serpins were performed.
Main Results:
- * A novel sea lamprey serpin gene was successfully cloned, with predicted signal peptide and liver-specific mRNA expression.
- * Serpin mRNA levels increased during larval stages, peaking in late larvae, followed by a significant drop at metamorphosis.
- * Expression patterns correlated with circulating thyroid hormone levels, suggesting a role in metamorphosis.
- * Sequence analysis indicated the sea lamprey serpin possesses features consistent with inhibitory function, including specific P1/P1' residues and structural elements for reactive center loop insertion.
Conclusions:
- * The cloned sea lamprey serpin is a developmentally regulated gene potentially involved in metamorphosis.
- * Its expression is likely influenced by thyroid hormones, highlighting a conserved regulatory mechanism.
- * The structural analysis supports its classification as a functional inhibitor within the serpin superfamily.