Amhr2-Cre-Mediated Global Tspo Knockout

Area of Science:

• Endocrinology
• Developmental Biology
• Genetics

Background:

• The role of translocator protein (TSPO) in cholesterol transport within steroidogenic cells is debated.
• Previous attempts to create Leydig cell-specific TSPO knockouts using Amhr2-Cre mice were unsuccessful, suggesting potential genetic linkage or developmental issues.

Purpose of the Study:

• To investigate the function of TSPO by generating and characterizing TSPO global knockout (gKO) mice using the Amhr2-Cre line.
• To explore the effects of TSPO deletion on embryonic development, steroidogenesis, and global gene expression.

Main Methods:

• Generation of Amhr2-Cre-mediated TSPO global knockout (gKO) mice.
• Analysis of blastocyst morphology and Mendelian ratios at early embryonic stages (E3.5-E4.5).
• Assessment of adult gKO mice for disturbances in lipid homeostasis, testosterone, and corticosterone levels.
• RNA-sequencing of adrenal glands and lungs from gKO mice to identify transcriptome changes.

Main Results:

• Amhr2-Cre expression during preimplantation stages led to global heterozygous and knockout mice, not conditional knockouts.
• TSPO deletion resulted in delayed preimplantation embryonic development (66.7% of blastocysts affected).
• Adult gKO mice showed altered neutral lipid homeostasis, reduced testosterone levels, and significant transcriptome changes in adrenal glands and lungs, including alterations in cholesterol-binding proteins.

Conclusions:

• The Amhr2-Cre line can be utilized to generate TSPO global knockout mice, serving as a novel global 'Cre deleter'.
• TSPO deficiency impairs early embryonic development, disrupts neutral lipid storage and steroidogenesis, and induces compensatory transcriptomic alterations.
• These findings provide new insights into the essential roles of TSPO beyond cholesterol transport in steroidogenic cells.