Functional diversification of a protease inhibitor gene in the genus Drosophila and its molecular basis

Börner, Stefan; Ragg, Hermann

doi:10.1016/j.gene.2008.02.004

Cited by 13 publications

(14 citation statements)

References 40 publications

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“…gambiae serpin-10 (four isoforms) and D. melanogaster serpin-4 (four alternatively spliced C-terminal exons) are nonsecreted serpins (33,52,53). The number of serpin-4 reactive center loop-encoding exons was compared in 12 Drosophila species and the number varied from three (in Drosophila persimilis and Drosophila pseudoobscura) up to nine (in Drosophila grimshawi) (54). Alternative splicing to generate different C termini was also observed in Tribolium castaneum serpins 1, 15, 20, and 28 (33,55).…”

Section: Discussionmentioning

confidence: 99%

Analysis of Mutually Exclusive Alternatively Spliced Serpin-1 Isoforms and Identification of Serpin-1 Proteinase Complexes in Manduca sexta Hemolymph

Ragan

Yang

et al. 2010

Journal of Biological Chemistry

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Mutually exclusive alternative splicing produces transcripts for 12 serpin-1 isoforms in Manduca sexta that differ only in the region encoding the carboxyl-terminal 36 -40-amino acid residues. This variable region includes the reactive center loop, which determines the inhibitory selectivity of the serpin. We investigated mRNA levels of individual serpin-1 isoforms by quantitative PCR. The 12 isoforms were expressed at similar levels in hemocytes, but in fat body isoform B mRNA was present at significantly higher levels than isoforms C, D, E, F, G, J, K, and Z. To investigate the presence of individual serpin-1 isoforms in plasma we used immunoaffinity purification of serpin-1 isoforms from M. sexta plasma, followed by two-dimensional PAGE and identification of protein spots by digestion with a series of proteinases and analysis of the resulting peptides by MALDI-TOF/TOF. We identified nine of the 12 serpin-1 isoforms and, through analysis of putative serpin-1-proteinase complexes, identified three endogenous M. sexta proteinase targets of serpin-1. Our results suggest that M. sexta serpin-1 isoforms A, E, and J can inhibit hemolymph proteinase 8, which activates the cytokine spätzle. At least one isoform of serpin-1 can inhibit hemocyte proteinase 1, another M. sexta blood proteinase. In addition, a complex of serpin-1K in a complex with M. sexta midgut chymotrypsin was identified, suggesting serpin-1 isoforms may also function to protect insect tissues from digestive proteinases that may leak into the hemocoel.Serpins are a superfamily of proteins that are named for being serine proteinase inhibitors, a function that many serpins perform. Serpins contain an exposed reactive center loop, formed from a region near the carboxyl-terminal end of the protein. A proteinase that begins to cleave a serpin in the reactive center loop typically becomes covalently bound to the serpin and inactivated. The proteinase active site serine forms an ester bond with the acyl group of the serpin P1 residue at the amino-terminal side of the scissile bond, but cannot complete the hydrolysis because the serpin reactive center loop rapidly inserts into the A ␤-sheet, moving the proteinase ϳ70 Å and deforming the proteinase catalytic site (1, 2). Extracelluar serpins exert control over serine proteinase cascades in vertebrate blood, including complement activation, blood clotting, and fibrinolysis (3, 4). In insects, serine proteinase cascades initiated by microbial infection elicit antimicrobial peptide production and lead to activation of prophenoloxidase, which catalyzes the melanization response (5-13 In insects, serpin genes have evolved alternative exon splicing, which produces variation in the sequence of much of the reactive center loop, producing multiple functional serpins from a single gene. This was first described in M. sexta serpin-1, which has 12 different copies of exon 9 that undergo mutually exclusive alternative splicing to produce 12 putative protein isoforms. These isoforms differ in their carboxyl-terminal 39 -46 ...

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Section: Discussionmentioning

confidence: 99%

Analysis of Mutually Exclusive Alternatively Spliced Serpin-1 Isoforms and Identification of Serpin-1 Proteinase Complexes in Manduca sexta Hemolymph

Ragan

Yang

et al. 2010

Journal of Biological Chemistry

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“…However, caution should be advised, because homoplasy due to convergent evolution currently cannot be excluded. The Spn4 gene is prone to recombination events, especially in the regions coding for the RSL region [19]. Unraveling the relationships of the Spn4 gene from fruit flies and neuroserpin orthologs from deuterostomes requires further investigation.…”

Section: Discussionmentioning

confidence: 99%

“…In other lineages, such as fungi, serpins seem to be rare. In some species phylogenetic relationships of serpin genes may be obscured further by a propensity for reciprocal or non-reciprocal exchange of cassette exons coding for the hypervariable reactive site loop region (RSL) [19]. The sequence of this region plays a primary role in determining the specificity of serpin/target enzyme interaction.…”

Section: Introductionmentioning

confidence: 99%

Ancestry and evolution of a secretory pathway serpin

Kumar

Ragg

2008

BMC Evol Biol

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BackgroundThe serpin (serine protease inhibitor) superfamily constitutes a class of functionally highly diverse proteins usually encompassing several dozens of paralogs in mammals. Though phylogenetic classification of vertebrate serpins into six groups based on gene organisation is well established, the evolutionary roots beyond the fish/tetrapod split are unresolved. The aim of this study was to elucidate the phylogenetic relationships of serpins involved in surveying the secretory pathway routes against uncontrolled proteolytic activity.ResultsHere, rare genomic characters are used to show that orthologs of neuroserpin, a prominent representative of vertebrate group 3 serpin genes, exist in early diverging deuterostomes and probably also in cnidarians, indicating that the origin of a mammalian serpin can be traced back far in the history of eumetazoans. A C-terminal address code assigning association with secretory pathway organelles is present in all neuroserpin orthologs, suggesting that supervision of cellular export/import routes by antiproteolytic serpins is an ancient trait, though subtle functional and compartmental specialisations have developed during their evolution. The results also suggest that massive changes in the exon-intron organisation of serpin genes have occurred along the lineage leading to vertebrate neuroserpin, in contrast with the immediately adjacent PDCD10 gene that is linked to its neighbour at least since divergence of echinoderms. The intron distribution pattern of closely adjacent and co-regulated genes thus may experience quite different fates during evolution of metazoans.ConclusionThis study demonstrates that the analysis of microsynteny and other rare characters can provide insight into the intricate family history of metazoan serpins. Serpins with the capacity to defend the main cellular export/import routes against uncontrolled endogenous and/or foreign proteolytic activity represent an ancient trait in eukaryotes that has been maintained continuously in metazoans though subtle changes affecting function and subcellular location have evolved. It is shown that the intron distribution pattern of neuroserpin gene orthologs has undergone substantial rearrangements during metazoan evolution.

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“…Alternative splicing at the same position, to produce serpins with differing RCLs also occurs in An. gambiae SRPN10 [27] and in spn4 orthologs in multiple Drosophila species [28] (discussed more in Section 2.3).…”

Section: Introductionmentioning

confidence: 99%

Serpins in arthropod biology

Meekins

Kanost

Michel

2017

Seminars in Cell & Developmental Biology

147

145

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Serpins are the largest known family of serine proteinase inhibitors and perform a variety of physiological functions in arthropods. Herein, we review the field of serpins in arthropod biology, providing an overview of current knowledge and topics of interest. Serpins regulate insect innate immunity via inhibition of serine proteinase cascades that initiate immune responses such as melanization and antimicrobial peptide production. In addition, several serpins with anti-pathogen activity are expressed as acute-phase serpins in insects upon infection. Parasitoid wasps can downregulate host serpin expression to modulate the host immune system. In addition, examples of serpin activity in development and reproduction in Drosophila have also been discovered. Serpins also function in host-pathogen interactions beyond immunity as constituents of venom in parasitoid wasps and saliva of blood-feeding ticks and mosquitoes. These serpins have distinct effects on immunosuppression and anticoagulation and are of interest for vaccine development. Lastly, the known structures of arthropod serpins are discussed, which represent the serpin inhibitory mechanism and provide a detailed overview of the process.

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Functional diversification of a protease inhibitor gene in the genus Drosophila and its molecular basis

Cited by 13 publications

References 40 publications

Analysis of Mutually Exclusive Alternatively Spliced Serpin-1 Isoforms and Identification of Serpin-1 Proteinase Complexes in Manduca sexta Hemolymph

Analysis of Mutually Exclusive Alternatively Spliced Serpin-1 Isoforms and Identification of Serpin-1 Proteinase Complexes in Manduca sexta Hemolymph

Ancestry and evolution of a secretory pathway serpin

Serpins in arthropod biology

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