Is FAS/Fas ligand system involved in equine corpus luteum functional regression?

Area of Science:

• Reproductive biology and endocrinology
• Cellular and molecular biology
• Veterinary science

Background:

• The role of Fas ligand (FASL) and its receptor FAS in corpus luteum (CL) function and steroidogenesis is not well understood.
• These molecules are part of the tumor necrosis factor superfamily and are known to induce apoptosis.

Purpose of the Study:

• To investigate the presence of FASL and FAS in the mare's CL throughout the luteal phase.
• To determine the impact of FASL, alone or with TNF and IFNG, on equine luteal cell function, including steroid production, viability, and apoptosis.

Main Methods:

• Western blotting and real-time PCR were used to assess FASL and FAS protein and mRNA expression in equine CL at different stages.
• Immunohistochemistry localized FAS and FASL proteins within CL cells.
• Equine luteal cells were stimulated in vitro with FASL, TNF+IFNG, or FASL+TNF+IFNG to evaluate effects on progesterone, PGE(2), PGF(2alpha), cell viability, and apoptosis.

Main Results:

• FASL and FAS protein and mRNA expression increased in the late luteal phase of the mare's CL.
• FASL and FAS proteins were detected in steroidogenic and endothelial cells of the CL.
• FASL inhibited progesterone and PGE(2) production while increasing PGF(2alpha) production by equine luteal cells.
• The effect of FASL on cell viability was modulated by the presence of TNF and IFNG.

Conclusions:

• FASL and FAS are present in the equine corpus luteum and play a role in regulating luteal function.
• These findings suggest the involvement of the FASL/FAS system in the process of functional luteolysis in mares.
• The study highlights the potential of FASL as a regulator of steroidogenesis and cell fate in the equine CL.