Bovine Lhx8, a Germ Cell-Specific Nuclear Factor, Interacts with Figla

Area of Science:

• Reproductive Biology
• Developmental Biology
• Genetics

Background:

• LIM homeobox 8 (Lhx8) is a germ cell transcription factor vital for oocyte development.
• Lhx8 deficiency in mice leads to oocyte loss and altered gene expression.

Purpose of the Study:

• Characterize the bovine Lhx8 gene and its splice variant.
• Determine Lhx8 mRNA expression during bovine oocyte and early embryo development.
• Investigate Lhx8 interactions with other oocyte-specific transcription factors.

Main Methods:

• Gene characterization and splice variant identification.
• mRNA expression analysis using RT-PCR in gonadal and somatic tissues, and isolated oocytes.
• Protein localization studies in mammalian cells.
• Co-immunoprecipitation assays to detect protein interactions.

Main Results:

• The bovine Lhx8 gene encodes a 377-amino acid protein with two LIM domains and one homeobox domain.
• A splice variant, Lhx8_v1, with an incomplete LIM domain was identified.
• Lhx8 and Lhx8_v1 transcripts were exclusively detected in gonads, specifically within oocytes, not in somatic or granulosa/theca cells.
• Maternal Lhx8 transcripts were abundant in GV and MII oocytes and early embryos, decreasing by the morula stage.
• A nuclear localization signal was identified, and Lhx8 was found to be predominantly nuclear.
• A novel interaction between Lhx8 and the transcription factor Figla was discovered.

Conclusions:

• Bovine Lhx8 plays a critical role in oocyte development and early embryogenesis.
• The tissue- and cell-specific expression pattern highlights its importance in germ cells.
• The interaction with Figla suggests a coordinated regulatory network in oogenesis.