Incompletely processed LH molecules synthesized by rat gonadotrophs treated with inhibitors of oligosaccharide processing

Ovarian hyperplasia linked to a mutation in MAN1A2 in a cow with excessive follicular growth and functional oocytes

Here we report the case of a cow with two ovaries that each exhibited hyperplasia but that otherwise had normal gross morphology. Both ovaries had a large number of tertiary follicles on the ovarian surface. Oocytes from one ovary were studied in more detail. The transcriptome was largely similar to other oocytes. Oocytes could undergo cleavage at a rate consistent with other oocytes and result in blastocyst-stage embryo formation after in vitro maturation and fertilization. Review of the literature from cattle and other species did not reveal reports of a similar type of spontaneous ovarian abnormality. Whole genome sequencing revealed many single nucleotide polymorphisms with predicted large effects on protein structure that could potentially be causative for the phenotype. The variant considered most likely to cause the observed alteration in ovarian function was a mutation in the glycoprotein-modifying enzyme MAN1A2.

Proteolytically activated, recombinant anti-mullerian hormone inhibits androgen secretion, proliferation, and differentiation of spermatogonia in adult zebrafish testis organ cultures

Anti-Müllerian hormone (Amh) is in mammals known as a TGFβ type of glycoprotein processed to yield a bioactive C-terminal homodimer that directs regression of Müllerian ducts in the male fetus and regulates steroidogenesis and early stages of folliculogenesis. Here, we report on the zebrafish Amh homologue. Zebrafish, as all teleost fish, do not have Müllerian ducts. Antibodies raised against the N- and C-terminal part of Amh were used to study the processing of endogenous and recombinant Amh. The N-terminally directed antibody detected a 27-kDa protein, whereas the C-terminally directed one recognized a 32-kDa protein in testes extracts, both apparently not glycosylated. The C-terminal fragment was present as a monomeric protein, because reducing conditions did not change its apparent molecular mass. Recombinant zebrafish Amh was cleaved with plasmin to N- and C-terminal fragments that after deglycosylation were similar in size to endogenous Amh fragments. Mass spectrometry and N-terminal sequencing revealed a 21-residue N-terminal leader sequence and a plasmin cleavage site after Lys or Arg within Lys-Arg-His at position 263-265, which produce theoretical fragments in accordance with the experimental results. Experiments using adult zebrafish testes tissue cultures showed that plasmin-cleaved, but not uncleaved, Amh inhibited gonadotropin-stimulated androgen production. However, androgens did not modulate amh expression that was, on the other hand, down-regulated by Fsh. Moreover, plasmin-cleaved Amh inhibited androgen-stimulated proliferation as well as differentiation of type A spermatogonia. In conclusion, zebrafish Amh is processed to become bioactive and has independent functions in inhibiting both steroidogenesis and spermatogenesis.

Molecular structures of glycoprotein hormones and functions of their carbohydrate components

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