Relating tissue specialization to the differentiation of expression of singleton and duplicate mouse proteins.
BACKGROUND
Gene duplications have been hypothesized to be a major factor in enabling the evolution of tissue differentiation. Analyses of the expression profiles of duplicate genes in mammalian tissues have indicated that, with time, the expression patterns of duplicate genes diverge and become more tissue specific. We explored the relationship between duplication events, the time at which they took place, and both the expression breadth of the duplicated genes and the cumulative expression breadth of the gene family to which they belong.


RESULTS
We show that only duplicates that arose through post-multicellularity duplication events show a tendency to become more specifically expressed, whereas such a tendency is not observed for duplicates that arose in a unicellular ancestor. Unlike the narrow expression profile of the duplicated genes, the overall expression of gene families tends to maintain a global expression pattern.


CONCLUSIONS
The work presented here supports the view suggested by the subfunctionalization model, namely that expression divergence in different tissues, following gene duplication, promotes the retention of a gene in the genome of multicellular species. The global expression profile of the gene families suggests division of expression between family members, whose expression becomes specialized. Because specialization of expression is coupled with an increased rate of sequence divergence, it can facilitate the evolution of new, tissue-specific functions.
Freilich
Shiri
S
EMBL-EBI, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SB, UK. shirigo@ebi.ac.uk
Massingham
Tim
T
Blanc
Eric
E
Goldovsky
Leon
L
Thornton
Janet M
JM
D000818:Animals; D002454:Cell Differentiation; D019143:Evolution, Molecular; D020440:Gene Duplication; D005786:Gene Expression Regulation; D020131:Genes, Duplicate; D007700:Kinetics; D051379:Mice; D011506:Proteins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D011506:Proteins