Abundance of female-biased and paucity of male-biased somatically expressed genes on the mouse X-chromosome [Elektronisk resurs]

• BACKGROUND: Empirical evaluations of sexually dimorphic expression of genes on the mammalian X-chromosome are needed to understand the evolutionary forces and the gene-regulatory mechanisms controlling this chromosome. We performed a large-scale sex-bias expression analysis of genes on the X-chromosome in six different somatic tissues from mouse. RESULTS: Our results show that the mouse X-chromosome is enriched with female-biased genes and depleted of male-biased genes. This suggests that feminisation as well as de-masculinisation of the X-chromosome has occurred in terms of gene expression in non-reproductive tissues. Several mechanisms may be responsible for the control of female-biased expression on chromosome X, and escape from X-inactivation is a main candidate. We confirmed escape in case of Tmem29 using RNA-FISH analysis. In addition, we identified novel female-biased non-coding transcripts located in the same female-biased cluster as the well-known coding X-inactivation escapee Kdm5c, likely transcribed from the transition-region between active and silenced domains. We also found that previously known escapees only partially explained the overrepresentation of female-biased X-genes, particularly for tissue-specific female-biased genes. Therefore, the gene set we have identified contains tissue-specific escapees and/or genes controlled by other sexually skewed regulatory mechanisms. Analysis of gene age showed that evolutionarily old X-genes (>100 myr, preceding the radiation of placental mammals) are more frequently female-biased than younger genes. CONCLUSION: Altogether, our results have implications for understanding both gene regulation and gene evolution of mammalian X-chromosomes, and suggest that the final result in terms of the X-gene composition (masculinisation versus feminisation) is a compromise between different evolutionary forces acting on reproductive and somatic tissues. 

Ämnesord

Natural Sciences  (hsv)

Biological Sciences  (hsv)

Genetics  (hsv)

Naturvetenskap  (hsv)

Biologiska vetenskaper  (hsv)

Genetik  (hsv)

Genetics  (uu)

Genetik  (uu)

Biologi med inriktning mot zoologisk utvecklingsbiologi  (uu)

Biology with specialization in Animal Development  (uu)

Biology with specialization in Molecular Biology  (uu)

Biologi med inriktning mot molekylärbiologi  (uu)

Indexterm och SAB-rubrik

X-chromosome

Sex chromosome; Somatic; Gene expression; Sexual antagonism; Sexual selection; Gender; Sex-bias; Female-bias; Male-bias; Sexual dimorphism; Dosage compensation; X-inactivation; Escape; Feminisation; Masculinisation; De-masculinisation; Microarray; Non-coding RNA; lncRNA; Tmem29; Kdm5c; Xist