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Structural and functional diversification in the teleost S100 family of calcium-binding proteins.

Kraemer AM, Saraiva LR, Korsching SI - BMC Evol. Biol. (2008)

Bottom Line: Individual species feature distinctive subsets of thirteen to fourteen genes that result from local gene duplications and gene losses.Several S100 family members are found in jawless fish already, but none of them are clear orthologs of cartilaginous or bony fish s100 genes.Accordingly, our findings provide an excellent basis for future studies of the functions and interaction partners of s100 genes and finally their role in diseases, using the zebrafish as a model organism.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Genetics, University of Cologne, Zuelpicher Strasse 47, 50674 Cologne, Germany. a.kraemer@gmx.com

ABSTRACT

Background: Among the EF-Hand calcium-binding proteins the subgroup of S100 proteins constitute a large family with numerous and diverse functions in calcium-mediated signaling. The evolutionary origin of this family is still uncertain and most studies have examined mammalian family members.

Results: We have performed an extensive search in several teleost genomes to establish the s100 gene family in fish. We report that the teleost S100 repertoire comprises fourteen different subfamilies which show remarkable similarity across six divergent teleost species. Individual species feature distinctive subsets of thirteen to fourteen genes that result from local gene duplications and gene losses. Eight of the fourteen S100 subfamilies are unique for teleosts, while six are shared with mammalian species and three of those even with cartilaginous fish. Several S100 family members are found in jawless fish already, but none of them are clear orthologs of cartilaginous or bony fish s100 genes. All teleost s100 genes show the expected structural features and are subject to strong negative selection. Many aspects of the genomic arrangement and location of mammalian s100 genes are retained in the teleost s100 gene family, including a completely conserved intron/exon border between the two EF hands. Zebrafish s100 genes exhibit highly specific and characteristic expression patterns, showing both redundancy and divergence in their cellular expression. In larval tissue expression is often restricted to specific cell types like keratinocytes, hair cells, ionocytes and olfactory receptor neurons as demonstrated by in situ hybridization.

Conclusion: The origin of the S100 family predates at least the segregation of jawed from jawless fish and some extant family members predate the divergence of bony from cartilaginous fish. Despite a complex pattern of gene gains and losses the total repertoire size is remarkably constant between species. On the expression level the teleost S100 proteins can serve as precise markers for several different cell types. At least some of their functions may be related to those of their counterparts in mammals. Accordingly, our findings provide an excellent basis for future studies of the functions and interaction partners of s100 genes and finally their role in diseases, using the zebrafish as a model organism.

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Expression of ten s100 genes in adult zebrafish by RT-PCR. mRNA was extracted from adult zebrafish tissue and transcribed into cDNA. Primer positions for PCR see Materials and Methods. Twelve different tissues were examined (barbels and lips, bone, brain, eyes, genitourinary tissue, gills, heart, liver, muscle, olfactory bulb, olfactory epithelium, skin). Band intensity was quantified to obtain an estimate of abundance to compare expression levels of several genes at least within the same tissue. Asterisks indicate bands at unexpected size (resulting from unspecific amplification) that were not quantified.
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Figure 7: Expression of ten s100 genes in adult zebrafish by RT-PCR. mRNA was extracted from adult zebrafish tissue and transcribed into cDNA. Primer positions for PCR see Materials and Methods. Twelve different tissues were examined (barbels and lips, bone, brain, eyes, genitourinary tissue, gills, heart, liver, muscle, olfactory bulb, olfactory epithelium, skin). Band intensity was quantified to obtain an estimate of abundance to compare expression levels of several genes at least within the same tissue. Asterisks indicate bands at unexpected size (resulting from unspecific amplification) that were not quantified.

Mentions: For a higher spatial resolution of the expression patterns at the cellular level we performed whole mount in situ hybridization of zebrafish larvae 5 days post fertilization. At this stage zebrafish have completed organogenesis and major behavioral patterns are already functional. Eight of ten genes analyzed show expression in the larval stage, with expression patterns ranging from highly restricted to spatially broad distributions (Figs. 8, 9, 10, 11, 12, 13, 14). The results of the in situ hybridizations are often consistent with those from the RT-PCR (Figure 7). A general tendency of the RT-PCR to show broader expression may be related to the higher sensitivity of that method compared to in situ hybridization. Additionally, a developmental regulation, i.e. a late onset of expression, may explain some of the differences in the results, especially the absence of two S100 transcripts (A1 and B) in larval tissues (although technical reasons cannot be ruled out for A1). For S100B a late onset of expression was confirmed by the detection of strong signals in adult brain (data not shown).


Structural and functional diversification in the teleost S100 family of calcium-binding proteins.

Kraemer AM, Saraiva LR, Korsching SI - BMC Evol. Biol. (2008)

Expression of ten s100 genes in adult zebrafish by RT-PCR. mRNA was extracted from adult zebrafish tissue and transcribed into cDNA. Primer positions for PCR see Materials and Methods. Twelve different tissues were examined (barbels and lips, bone, brain, eyes, genitourinary tissue, gills, heart, liver, muscle, olfactory bulb, olfactory epithelium, skin). Band intensity was quantified to obtain an estimate of abundance to compare expression levels of several genes at least within the same tissue. Asterisks indicate bands at unexpected size (resulting from unspecific amplification) that were not quantified.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2266712&req=5

Figure 7: Expression of ten s100 genes in adult zebrafish by RT-PCR. mRNA was extracted from adult zebrafish tissue and transcribed into cDNA. Primer positions for PCR see Materials and Methods. Twelve different tissues were examined (barbels and lips, bone, brain, eyes, genitourinary tissue, gills, heart, liver, muscle, olfactory bulb, olfactory epithelium, skin). Band intensity was quantified to obtain an estimate of abundance to compare expression levels of several genes at least within the same tissue. Asterisks indicate bands at unexpected size (resulting from unspecific amplification) that were not quantified.
Mentions: For a higher spatial resolution of the expression patterns at the cellular level we performed whole mount in situ hybridization of zebrafish larvae 5 days post fertilization. At this stage zebrafish have completed organogenesis and major behavioral patterns are already functional. Eight of ten genes analyzed show expression in the larval stage, with expression patterns ranging from highly restricted to spatially broad distributions (Figs. 8, 9, 10, 11, 12, 13, 14). The results of the in situ hybridizations are often consistent with those from the RT-PCR (Figure 7). A general tendency of the RT-PCR to show broader expression may be related to the higher sensitivity of that method compared to in situ hybridization. Additionally, a developmental regulation, i.e. a late onset of expression, may explain some of the differences in the results, especially the absence of two S100 transcripts (A1 and B) in larval tissues (although technical reasons cannot be ruled out for A1). For S100B a late onset of expression was confirmed by the detection of strong signals in adult brain (data not shown).

Bottom Line: Individual species feature distinctive subsets of thirteen to fourteen genes that result from local gene duplications and gene losses.Several S100 family members are found in jawless fish already, but none of them are clear orthologs of cartilaginous or bony fish s100 genes.Accordingly, our findings provide an excellent basis for future studies of the functions and interaction partners of s100 genes and finally their role in diseases, using the zebrafish as a model organism.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Genetics, University of Cologne, Zuelpicher Strasse 47, 50674 Cologne, Germany. a.kraemer@gmx.com

ABSTRACT

Background: Among the EF-Hand calcium-binding proteins the subgroup of S100 proteins constitute a large family with numerous and diverse functions in calcium-mediated signaling. The evolutionary origin of this family is still uncertain and most studies have examined mammalian family members.

Results: We have performed an extensive search in several teleost genomes to establish the s100 gene family in fish. We report that the teleost S100 repertoire comprises fourteen different subfamilies which show remarkable similarity across six divergent teleost species. Individual species feature distinctive subsets of thirteen to fourteen genes that result from local gene duplications and gene losses. Eight of the fourteen S100 subfamilies are unique for teleosts, while six are shared with mammalian species and three of those even with cartilaginous fish. Several S100 family members are found in jawless fish already, but none of them are clear orthologs of cartilaginous or bony fish s100 genes. All teleost s100 genes show the expected structural features and are subject to strong negative selection. Many aspects of the genomic arrangement and location of mammalian s100 genes are retained in the teleost s100 gene family, including a completely conserved intron/exon border between the two EF hands. Zebrafish s100 genes exhibit highly specific and characteristic expression patterns, showing both redundancy and divergence in their cellular expression. In larval tissue expression is often restricted to specific cell types like keratinocytes, hair cells, ionocytes and olfactory receptor neurons as demonstrated by in situ hybridization.

Conclusion: The origin of the S100 family predates at least the segregation of jawed from jawless fish and some extant family members predate the divergence of bony from cartilaginous fish. Despite a complex pattern of gene gains and losses the total repertoire size is remarkably constant between species. On the expression level the teleost S100 proteins can serve as precise markers for several different cell types. At least some of their functions may be related to those of their counterparts in mammals. Accordingly, our findings provide an excellent basis for future studies of the functions and interaction partners of s100 genes and finally their role in diseases, using the zebrafish as a model organism.

Show MeSH
Related in: MedlinePlus