Stage-Specific L-Proline Uptake by Amino Acid Transporter Slc6a19/B⁰AT1 Is Required for Optimal Preimplantation...

Area of Science:

• Reproductive biology
• Developmental biology
• Molecular biology

Background:

• L-proline (Pro) supports normal mouse embryo development.
• Pro improves embryo development when added to fertilization medium.
• Mechanisms of Pro's effect involve signaling pathways observed in stem cell differentiation.

Purpose of the Study:

• Investigate the role of the neutral amino acid transporter B⁰AT1 in mouse preimplantation embryo development.
• Determine the contribution of B⁰AT1 to L-proline uptake and its impact on embryo development.
• Explore potential transporter redundancy in preimplantation embryos.

Main Methods:

• Expression analysis of B⁰AT1 and ACE2 in mouse preimplantation embryos.
• Fertility assessment of B⁰AT1 knockout (Slc6a19) mice.
• In vitro embryo development assays with and without L-proline supplementation.
• Radiolabeled L-proline uptake studies in wild-type and knockout embryos.
• Competition assays with other amino acids to assess transporter specificity.

Main Results:

• B⁰AT1 and ACE2 are expressed in mouse preimplantation embryos.
• B⁰AT1 knockout mice exhibit reduced fertility and impaired in vitro embryo development.
• Radiolabeled Pro uptake is reduced in 4-8-cell stage embryos from knockout mice.
• L-proline supplementation improves embryo development in both wild-type and knockout embryos, with stage-specific effects.
• B⁰AT1 is identified as the primary transporter for Pro uptake on day 4 of development.

Conclusions:

• B⁰AT1 plays a significant role in L-proline uptake and subsequent mouse embryo development.
• Transporter redundancy exists in preimplantation embryos, with B⁰AT1 being critical at specific developmental stages.
• Findings highlight the importance of amino acid transport for successful reproduction and embryonic development.