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. 2008 Aug 22;3(8):e3041.
doi: 10.1371/journal.pone.0003041.

A potential role for Drosophila mucins in development and physiology

Zulfeqhar A Syed  1 , Torleif Härd, Anne Uv, Iris F van Dijk-Härd
Affiliations

A potential role for Drosophila mucins in development and physiology

Zulfeqhar A Syed et al. PLoS One. .

Abstract

Vital vertebrate organs are protected from the external environment by a barrier that to a large extent consists of mucins. These proteins are characterized by poorly conserved repeated sequences that are rich in prolines and potentially glycosylated threonines and serines (PTS). We have now used the characteristics of the PTS repeat domain to identify Drosophila mucins in a simple bioinformatics approach. Searching the predicted protein database for proteins with at least 4 repeats and a high ST content, more than 30 mucin-like proteins were identified, ranging from 300-23000 amino acids in length. We find that Drosophila mucins are present at all stages of the fly life cycle, and that their transcripts localize to selective organs analogous to sites of vertebrate mucin expression. The results could allow for addressing basic questions about human mucin-related diseases in this model system. Additionally, many of the mucins are expressed in selective tissues during embryogenesis, thus revealing new potential functions for mucins as apical matrix components during organ morphogenesis.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Drosophila mucins and mucin-domain containing proteins.
The proteins that were analyzed in this study are illustrated (left) together with an overview of their stage and dominant tissue-specific expressions (right). Conserved protein domains were predicted using the EMBL-database and are shown together with the identified PTS repeats according to color code (bottom). In proteins classified as mucins, the PTS repeats (yellow = without cysteines, orange = with cysteines) make up at least one-third of total protein length. Proteins in which the PTS repeats constitute less than one-third of protein length, lack proline (brown) or have low ST content (Mur11-A2) were termed mucin-related proteins. Each protein was named according to protein class (Muc: Mucins and Mur: Mucin-related proteins) followed by the cytological position. Proteins marked with “*” were previously identified as Sgs1 (Muc25B), Sgs3 (Muc68Cb), Dp (Mur24F) and Tnc (Mur96B). The spatial and temporal expression of each Muc and Mur were compiled from embryonic in situ hybridizations (E), RT-PCR on larvae (L; first instar larvae to the left and dissected third instar larval organs to the right), RT-PCR on pupae (P) and RT-PCR on adults (A). Where applicable, the dominant organ-specific expression is illustrated by color code. (An extensive overview of expression data is given in Table S4).
Figure 2
Figure 2. Drosophila mucins and mucin-domain containing proteins are expressed throughout development.
Transcripts correlating to mucins and mucin-related proteins were detected by two-step RT-PCR (Reverse Transcription–PCR). A) Template RNA was isolated from embryos (E), first instar larvae (L1), third instar larvae (L3), early pupae (P1), late pupae (P2), adult females (Af) and adult males (Am), and the products separated on agarose gels. Primers for the 18S-rRNA gene were used as control. Samples imported from another gel are indicated with “*”. Multiple bands (as observed for Mur29B, Mur2B and Mur18B products) most likely arise from multiple priming sites, due to the repetitive nature of the gene sequences. B) Detection of transcripts in dissected larval organ was assessed by two-step RT-PCR. As positive control, primers for the 18S-rRNA gene were used.
Figure 3
Figure 3. Embryonic expression of Drosophila mucins and mucin-related proteins.
The embryonic expression pattern of each mucin and mucin-domain containing protein was detected by RNA in situ hybridizations on whole-mount embryos. A) Genes expressed in the salivary glands include Muc12Ea at stages 14 and 15, as well as Muc96D Mur89F, Mur2B and Mur11A from stage 13. All embryos are lateral views, anterior to the left. B) The expression of four genes was detected in the digestive tract. Muc26B and Mur29B are expressed in the late proventriculus (pv; stage 16/17; ventral view), whereas Muc55B (lateral view) and Muc18B (probe B; ventral view) are detected in the anterior midgut (am). Muc18B (probe B) is also expressed in the developing gut from stage 13, where it is seen in the anterior and posterior midgut primordia (amp and pmp; lateral view). C) Ectoderm-derived cells that will produce cuticle express mucins and mucin-domain containing proteins either before or after cuticle formation. Muc91C is detected only in late pharynx (ph; stage 17) and tracheal spiracular openings (tsb; dorsal views), but Mur24F, Mur96B and Mur18B (probe A) are expressed in ectodermal cells already prior to cuticle production, such as in the tracheal pits (trp), tracheal prosterior dorsal trunk (pdt), foregut (fg), hindgut (hg) and around the posterior spiracles (ps) (Mur24F stage 16 is dorsal view, the others lateral views). D) Muc30E is expressed exclusively in the amnioserosa throughout development (lateral views). E) One of the genes, Mur96B/tnc, is also detected in the central nervous system (CNS) when using probe B (lateral view). F) Probes directed against distinct parts of the Mur96B and Muc18B coding regions (A and B, as illustrated) gave different expression patterns.
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References

    1. Hollingsworth MA, Swanson BJ. Mucins in cancer: protection and control of the cell surface. Nat Rev Cancer. 2004;4:45–60. - PubMed
    1. Perez-Vilar J, Hill RL. The structure and assembly of secreted mucins. J Biol Chem. 1999;274:31751–31754. - PubMed
    1. Lang T, Hansson GC, Samuelsson T. Gel-forming mucins appeared early in metazoan evolution. Proc Natl Acad Sci U S A. 2007;104:16209–16214. - PMC - PubMed
    1. Wilkin MB, Becker MN, Mulvey D, Phan I, Chao A, et al. Drosophila dumpy is a gigantic extracellular protein required to maintain tension at epidermal-cuticle attachment sites. Curr Biol. 2000;10:559–567. - PubMed
    1. Fraichard S, Bouge AL, Chauvel I, Bouhin H. Tenectin, a novel extracellular matrix protein expressed during Drosophila melanogaster embryonic development. Gene Expr Patterns. 2006;6:772–776. - PubMed

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