GnRH regulates the expression of its receptor accessory protein SET in pituitary gonadotropes

Progesterone-primed cycles result in slower embryos without compromising implantation potential and with the advantages of oral administration and potential cost reduction

OBJECTIVE

To study the impact of the use of progesterone on embryo morphokinetics and on the outcomes of intracytoplasmic sperm injection cycles.

DESIGN

Cohort study.

SETTING

Private university-affiliated in vitro fertilization center.

PATIENT(S)

This study included 236 freeze-all intracytoplasmic sperm injection cycles and the resultant 2,768 injected oocytes cultured in a time-lapse imaging incubation system. Patients were matched by age and divided into groups depending on the protocol used to prevent the luteinizing hormone surge: progestin-primed (144 cycles and 1,360 embryos) and gonadotropin hormone-releasing hormone (GnRH) antagonist (144 cycles and 1,408 embryos) groups.

INTERVENTION(S)

The kinetic recorded markers were time to pronuclear appearance and fading, time to 2-8 cells, time to morulation, time to start of blastulation, and time to blastulation. The durations of cell cycles and time to complete synchronous divisions were calculated. The Known Implantation Data Score ranking was recorded. Morphokinetics and clinical outcomes were compared between the groups.

MAIN OUTCOME MEASURE(S)

Embryo morphokinetics and clinical outcomes.

RESULTS

Slower time to pronuclear appearance, time to 2 cells, time to 7 cells, time to start of blastulation, and time to blastulation were observed in embryos derived from progestin-primed cycles than in those from the GnRH antagonist group. No significant differences were noted in any other morphokinetic milestone. Significantly higher cancellation and implantation rates were observed in the progestin-primed group. However, no significant differences were noted in the pregnancy and miscarriage rates. The expenses for treatment using premature GnRH antagonist and progestins were US$318.18 and US$11.05, respectively.

CONCLUSIONS

Exogenous progesterone replaces the GnRH antagonist for the prevention of premature luteinizing hormone surge, in freeze-all cycles, with the advantage of oral administration and potential cost reduction.

The protein level of the tumor-promoting factor SET is regulated by cell density

SET/I2PP2A is a multifunctional protein that acts as an intrinsic inhibitor of the tumor suppressor protein phosphatase 2A and as a histone chaperone. Increased SET levels have been observed in various cancers; however, the underlying molecular mechanisms remain unclear. In this study, we found that SET protein accumulates with the increasing density of cultured cells. This phenomenon was observed not only in cancer cell lines but also in non-cancer cell lines. The mRNA levels of SET were not affected by the cell density. Proteasome inhibition decreased SET levels, whereas autophagy inhibition led to SET accumulation, indicating the involvement of autophagy. The mRNA and protein expression of SETBP1, which stabilizes the SET protein, increased with cell density. The decrease in SET level due to the loss of SETBP1 was more pronounced in wild-type cells than that in autophagy-deficient cells. These results have revealed a mechanism underlying the regulation of SET level, wherein increased cell density induces SETBP1 expression and protects SET from autophagy.

Proteomic Analysis of Brain Region and Sex-Specific Synaptic Protein Expression in the Adult Mouse Brain

Genetic disruption of synaptic proteins results in a whole variety of human neuropsychiatric disorders including intellectual disability, schizophrenia or autism spectrum disorder (ASD). In a wide range of these so-called synaptopathies a sex bias in prevalence and clinical course has been reported. Using an unbiased proteomic approach, we analyzed the proteome at the interaction site of the pre- and postsynaptic compartment, in the prefrontal cortex, hippocampus, striatum and cerebellum of male and female adult C57BL/6J mice. We were able to reveal a specific repertoire of synaptic proteins in different brain areas as it has been implied before. Additionally, we found a region-specific set of novel synaptic proteins differentially expressed between male and female individuals including the strong ASD candidates DDX3X, KMT2C, MYH10 and SET. Being the first comprehensive analysis of brain region-specific synaptic proteomes from male and female mice, our study provides crucial information on sex-specific differences in the molecular anatomy of the synapse. Our efforts should serve as a neurobiological framework to better understand the influence of sex on synapse biology in both health and disease.

Gonadotropin-releasing hormone-Cu complex (Cu-GnRH) transcriptional activity in vivo in the female rat anterior pituitary gland

Unlike gonadotropin-releasing hormone (GnRH) analogues characterized by amino acid replacement in decapeptide primary structure, Cu-GnRH molecule preserves the native sequence but contains a Cu²⁺ ion stably bound to the nitrogen atoms including that of the imidazole ring of His². Cu-GnRH can operate via cAMP/PKA signalling in anterior pituitary cells, suggesting that it may affect selected gonadotropic network gene transcription in vivo. We analysed pituitary mRNA expression of Egr-1, Nr5a1, and Lhb based on their role in luteinizing hormone (LH) synthesis; and Nos1, Adcyap1, and Prkaca due to their dependence on cAMP/PKA activity. In two independent experiments, ovariectomized rats received intracerebroventricular pulsatile (one pulse/h or two pulses/h over 5 h) microinjections of 2 nM Cu-GnRH; 2 nM antide (GnRH antagonist) + 2 nM Cu-GnRH; 100 nM PACAP_6-38 (PACAP receptor antagonist) + 2 nM Cu-GnRH. Relative expression of selected mRNAs was determined by qRT-PCR. LH serum concentration was examined according to RIA. All examined genes responded to Cu-GnRH stimulation with increased transcriptional activity in a manner dependent on pulse frequency pattern. Increased expression of Nr5a1, Lhb, Nos1, Adcyap1, and Prkaca mRNA was observed solely in rats receiving the complex with frequency of two pulses/h over 5 h. Egr-1 transcription was up-regulated for both applied Cu-GnRH pulsatile patterns. The stimulatory effect of Cu-GnRH on gene transcription was dependent on both GnRH receptor and PAC-1 activation. In conclusion, obtained results indicate that Cu-GnRH complex is a GnRH analogue able to induce both IP₃/PKC and cAMP/PKA-dependent gonadotrope network gene transcription in vivo.

Characterization of gonadotropin releasing hormone receptor gene in Sokoto and Kalahari Red goats

The objective of this study was to characterize GnRHR gene in Sokoto (n = 70) and Kalahari Red (n = 70) goats. Three SNPs, (g.-29T > G, g.48 G > A and g.209 T > G), were detected in Sokoto Red (SR) and one (g.48 G > A) in Kalahari Red (KR) goats. All the mutations occurred within the 5'UTR and Exon one of the gene and the g.209 T > G was non-synonymous and, therefore, resulted in an amino acid change from methionine to arginine at Position 70 of the GnRHR polypeptide. The homozygous mutant genotypes at the three SNP loci were not detected in both breeds but minor allele frequencies were ≥ 0.1 for the three SNP loci in SR goats. Frequency of the T allele, however, was 0.93 at the only SNP locus detected in KR goats. There was a strong linkage disequilibrium (LD; r²>0.98) among the detected mutations in SR goats resulting in two haplotypes (T-G-T and G-A-G) with a frequency of 86% and 13%, respectively. There was no significant association between genotypes at the polymorphic loci and litter size (P > 0.05) in the two breeds. The non-synonymous mutation (g.209T>G) appears to have changed the nucleotide binding region and area spanning exposed/buried regions on the predicted secondary structure of the two variants of the receptor. This change led to variation in the tertiary structure between the two variants of the receptor and can influence the function of the transmembrane receptor. Comparison of the GnRH receptor domains for goats, sheep, cattle and swine confirmed that the seven transmembrane domains of the receptor are conserved in all the farm animals considered.