Ontogeny of the Lim Code in the Mouse Gonads

Lim genes are developmentally regulated transcription factors involved in tissue specification and cell differentiation. Several Lim genes are present in the mammalian genome and each tissue expresses a unique pattern of Lim genes giving rise to the Lim code and it is believed that the Lim code is the determinant of the cell fate decisions taken by the tissue. In the developing mouse, Lhx9 and Lmo4 have been identified to play a key role in gonad specification and testis development; however the presence of other Lim genes and its co-regulators has not been reported. Recent evidences also suggest that the Lim genes are also expressed in other adult tissues. However, the presence of Lim genes in adult gonads has not been reported. In the present study we report the expression profiles of Lhx9, Lmo 1-4 and Clim 1 and 2 in the developing, neonatal and adult mouse gonads. Our results show that along with Lhx9, all the Lmos and Clims are expressed by the developing and adult gonads. With the exception of Lmo4, the expression of all these factors is sexually dimorphic with higher expression in the female gonads as compared to male gonads. Our results indicate that the Lim gene activity may be vital for ovarian development and functioning. It will be interesting to study the gonadal phenotypes of the Lim mutants to define their specific roles in the gonads.