Catfish gonadotrophins: cellular origin, structural properties and physiology.

Area of Science:

• Reproductive biology
• Endocrinology
• Fish biology

Background:

• Gonadotrophins (GTHs), including luteinising hormone (LH) and follicle-stimulating hormone (FSH), are crucial for gametogenesis and spawning in vertebrates.
• In teleost fish, GTHs are typically secreted from separate cells, with conserved α-subunits and LHβ, but divergent FSHβ.

Purpose of the Study:

• To investigate the structural characteristics and functional roles of GTHs and their receptors in teleost fish.
• To understand the differential regulation of reproduction by LH and FSH in teleosts, particularly in species with divergent FSHβ.

Main Methods:

• Phylogenetic analysis of GTH subunits.
• Characterization of GTH receptors (FSHR and LHR).
• Comparative analysis of GTH secretion patterns and reproductive control.

Main Results:

• FSHβ shows significant divergence in teleosts, with variations in cysteine residues and glycosylation sites.
• Teleost FSH receptors are promiscuous, cross-activated by LH, while LH receptors are highly selective.
• In catfishes lacking native FSH, LH alone governs all reproductive processes, from gametogenesis to spawning.

Conclusions:

• The structural divergence of FSHβ in teleosts influences GTH signaling pathways.
• Differential receptor selectivity and GTH secretion patterns highlight unique reproductive strategies in fish.
• LH plays a dominant role in reproduction in certain teleost species, underscoring its versatility.