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Multiple splice variants within the bovine silver homologue (SILV) gene affecting coat color in cattle indicate a function additional to fibril formation in melanophores.

Kuehn C, Weikard R - BMC Genomics (2007)

Bottom Line: In contrast to previous results in other species reporting SILV expression exclusively in pigmented tissues, our experiments provide evidence that the bovine SILV gene is expressed in a variety of tissues independent of pigmentation.Furthermore, the splice variants of the bovine SILV gene represent a comprehensive natural model to refine the knowledge about functional domains in the SILV protein.Our study exemplifies that the extent of alternative splicing is presumably much higher than previously estimated and that alternatively spliced transcripts presumably can generate molecules of deviating function compared to their constitutive counterpart.

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Affiliation: Research Institute for the Biology of Farm Animals (FBN), Res, Unit Molecular Biology, Wilhelm-Stahl-Allee 2, D-18196 Dummerstorf, Germany. kuehn@fbn-dummerstorf.de

ABSTRACT

Background: The silver homologue(SILV) gene plays a major role in melanosome development. SILV is a target for studies concerning melanoma diagnostics and therapy in humans as well as on skin and coat color pigmentation in many species ranging from zebra fish to mammals. However, the precise functional cellular mechanisms, in which SILV is involved, are still not completely understood. While there are many studies addressing SILV function upon a eumelaneic pigment background, there is a substantial lack of information regarding the further relevance of SILV, e.g. for phaeomelanosome development.

Results: In contrast to previous results in other species reporting SILV expression exclusively in pigmented tissues, our experiments provide evidence that the bovine SILV gene is expressed in a variety of tissues independent of pigmentation. Our data show that the bovine SILV gene generates an unexpectedly large number of different transcripts occurring in skin as well as in non-pigmented tissues, e.g. liver or mammary gland. The alternative splice sites are generated by internal splicing and primarily remove complete exons. Alternative splicing predominantly affects the repeat domain of the protein, which has a functional key role in fibril formation during eumelanosome development.

Conclusion: The expression of the bovine SILV gene independent of pigmentation suggests SILV functions exceeding melanosome development in cattle. This hypothesis is further supported by transcript variants lacking functional key elements of the SILV protein relevant for eumelanosome development. Thus, the bovine SILV gene can serve as a model for the investigation of the putative additional functions of SILV. Furthermore, the splice variants of the bovine SILV gene represent a comprehensive natural model to refine the knowledge about functional domains in the SILV protein. Our study exemplifies that the extent of alternative splicing is presumably much higher than previously estimated and that alternatively spliced transcripts presumably can generate molecules of deviating function compared to their constitutive counterpart.

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Splice site specific SILV RT-PCR in non-pigmented bovine tissues. Detection of SILV splice variant Δ816–1340 by splice site specific RT-PCR with primers SPex6AF1 – E9R2 in RNA from non-pigmented tissues. mg: mammary gland, ki: kidney, he: heart, lu: lung, pg: pituitary gland, du: duodenum, li: liver, sk: skin. M: marker; C: negative control
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Figure 6: Splice site specific SILV RT-PCR in non-pigmented bovine tissues. Detection of SILV splice variant Δ816–1340 by splice site specific RT-PCR with primers SPex6AF1 – E9R2 in RNA from non-pigmented tissues. mg: mammary gland, ki: kidney, he: heart, lu: lung, pg: pituitary gland, du: duodenum, li: liver, sk: skin. M: marker; C: negative control

Mentions: While alternative splice variants were rather uniformly distributed across the differentially pigmented skins, substantial variation was seen for the other tissues (Table 4). Only transcript variant Δ105–362 was tissue-specific for skin. Whereas splice variant Δ816–1340 could be detected in all seven tissues tested (Figure 6), Δ1185–1340 was only found in mammary gland at a low level.


Multiple splice variants within the bovine silver homologue (SILV) gene affecting coat color in cattle indicate a function additional to fibril formation in melanophores.

Kuehn C, Weikard R - BMC Genomics (2007)

Splice site specific SILV RT-PCR in non-pigmented bovine tissues. Detection of SILV splice variant Δ816–1340 by splice site specific RT-PCR with primers SPex6AF1 – E9R2 in RNA from non-pigmented tissues. mg: mammary gland, ki: kidney, he: heart, lu: lung, pg: pituitary gland, du: duodenum, li: liver, sk: skin. M: marker; C: negative control
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2099443&req=5

Figure 6: Splice site specific SILV RT-PCR in non-pigmented bovine tissues. Detection of SILV splice variant Δ816–1340 by splice site specific RT-PCR with primers SPex6AF1 – E9R2 in RNA from non-pigmented tissues. mg: mammary gland, ki: kidney, he: heart, lu: lung, pg: pituitary gland, du: duodenum, li: liver, sk: skin. M: marker; C: negative control
Mentions: While alternative splice variants were rather uniformly distributed across the differentially pigmented skins, substantial variation was seen for the other tissues (Table 4). Only transcript variant Δ105–362 was tissue-specific for skin. Whereas splice variant Δ816–1340 could be detected in all seven tissues tested (Figure 6), Δ1185–1340 was only found in mammary gland at a low level.

Bottom Line: In contrast to previous results in other species reporting SILV expression exclusively in pigmented tissues, our experiments provide evidence that the bovine SILV gene is expressed in a variety of tissues independent of pigmentation.Furthermore, the splice variants of the bovine SILV gene represent a comprehensive natural model to refine the knowledge about functional domains in the SILV protein.Our study exemplifies that the extent of alternative splicing is presumably much higher than previously estimated and that alternatively spliced transcripts presumably can generate molecules of deviating function compared to their constitutive counterpart.

View Article: PubMed Central - HTML - PubMed

Affiliation: Research Institute for the Biology of Farm Animals (FBN), Res, Unit Molecular Biology, Wilhelm-Stahl-Allee 2, D-18196 Dummerstorf, Germany. kuehn@fbn-dummerstorf.de

ABSTRACT

Background: The silver homologue(SILV) gene plays a major role in melanosome development. SILV is a target for studies concerning melanoma diagnostics and therapy in humans as well as on skin and coat color pigmentation in many species ranging from zebra fish to mammals. However, the precise functional cellular mechanisms, in which SILV is involved, are still not completely understood. While there are many studies addressing SILV function upon a eumelaneic pigment background, there is a substantial lack of information regarding the further relevance of SILV, e.g. for phaeomelanosome development.

Results: In contrast to previous results in other species reporting SILV expression exclusively in pigmented tissues, our experiments provide evidence that the bovine SILV gene is expressed in a variety of tissues independent of pigmentation. Our data show that the bovine SILV gene generates an unexpectedly large number of different transcripts occurring in skin as well as in non-pigmented tissues, e.g. liver or mammary gland. The alternative splice sites are generated by internal splicing and primarily remove complete exons. Alternative splicing predominantly affects the repeat domain of the protein, which has a functional key role in fibril formation during eumelanosome development.

Conclusion: The expression of the bovine SILV gene independent of pigmentation suggests SILV functions exceeding melanosome development in cattle. This hypothesis is further supported by transcript variants lacking functional key elements of the SILV protein relevant for eumelanosome development. Thus, the bovine SILV gene can serve as a model for the investigation of the putative additional functions of SILV. Furthermore, the splice variants of the bovine SILV gene represent a comprehensive natural model to refine the knowledge about functional domains in the SILV protein. Our study exemplifies that the extent of alternative splicing is presumably much higher than previously estimated and that alternatively spliced transcripts presumably can generate molecules of deviating function compared to their constitutive counterpart.

Show MeSH
Related in: MedlinePlus