HtrA2 is up-regulated in the rat testis after experimental cryptorchidism

Antagonistic regulation of spermatogonial differentiation in zebrafish (Danio rerio) by Igf3 and Amh

Fsh-mediated regulation of zebrafish spermatogenesis includes modulating the expression of testicular growth factors. Here, we study if and how two Sertoli cell-derived Fsh-responsive growth factors, anti-Müllerian hormone (Amh; inhibiting steroidogenesis and germ cell differentiation) and insulin-like growth factor 3 (Igf3; stimulating germ cell differentiation), cooperate in regulating spermatogonial development. In dose response and time course experiments with primary testis tissue cultures, Fsh up-regulated igf3 transcript levels and down-regulated amh transcript levels; igf3 transcript levels were more rapidly up-regulated and responded to lower Fsh concentrations than were required to decrease amh mRNA levels. Quantification of immunoreactive Amh and Igf3 on testis sections showed that Fsh increased slightly Igf3 staining but decreased clearly Amh staining. Studying the direct interaction of the two growth factors showed that Amh compromised Igf3-stimulated proliferation of type A (both undifferentiated [A_und] and differentiating [A_diff]) spermatogonia. Also the proliferation of those Sertoli cells associated with A_und spermatogonia was reduced by Amh. To gain more insight into how Amh inhibits germ cell development, we examined Amh-induced changes in testicular gene expression by RNA sequencing. The majority (69%) of the differentially expressed genes was down-regulated by Amh, including several stimulators of spermatogenesis, such as igf3 and steroidogenesis-related genes. At the same time, Amh increased the expression of inhibitory signals, such as inha and id3, or facilitated prostaglandin E₂ (PGE₂) signaling. Evaluating one of the potentially inhibitory signals, we indeed found in tissue culture experiments that PGE₂ promoted the accumulation of A_und at the expense of A_diff and B spermatogonia. Our data suggest that an important aspect of Fsh bioactivity in stimulating spermatogenesis is implemented by restricting the different inhibitory effects of Amh and by counterbalancing them with stimulatory signals, such as Igf3.

Multiscale modelling of relationships between protein classes and drug behavior across all diseases using the CANDO platform

We have examined the effect of eight different protein classes (channels, GPCRs, kinases, ligases, nuclear receptors, proteases, phosphatases, transporters) on the benchmarking performance of the CANDO drug discovery and repurposing platform (http://protinfo.org/cando). The first version of the CANDO platform utilizes a matrix of predicted interactions between 48278 proteins and 3733 human ingestible compounds (including FDA approved drugs and supplements) that map to 2030 indications/diseases using a hierarchical chem and bio-informatic fragment based docking with dynamics protocol (> one billion predicted interactions considered). The platform uses similarity of compound-proteome interaction signatures as indicative of similar functional behavior and benchmarking accuracy is calculated across 1439 indications/diseases with more than one approved drug. The CANDO platform yields a significant correlation (0.99, p-value < 0.0001) between the number of proteins considered and benchmarking accuracy obtained indicating the importance of multitargeting for drug discovery. Average benchmarking accuracies range from 6.2 % to 7.6 % for the eight classes when the top 10 ranked compounds are considered, in contrast to a range of 5.5 % to 11.7 % obtained for the comparison/control sets consisting of 10, 100, 1000, and 10000 single best performing proteins. These results are generally two orders of magnitude better than the average accuracy of 0.2% obtained when randomly generated (fully scrambled) matrices are used. Different indications perform well when different classes are used but the best accuracies (up to 11.7% for the top 10 ranked compounds) are achieved when a combination of classes are used containing the broadest distribution of protein folds. Our results illustrate the utility of the CANDO approach and the consideration of different protein classes for devising indication specific protocols for drug repurposing as well as drug discovery.

Generation and characterization of mice with a conditional null allele of the HtrA4 gene

High temperature requirement factor A4 (HtrA4) is a member of the HtrA family of serine peptidases involved in regulating protein-protein interactions. Little is known regarding the function of HtrA4 in humans and in mouse models. To gain insights into the role of HtrA4 in vivo, mice were generated with a conditional null allele of HtrA4 by flanking exons 4, 5 and 6 with loxP sites. Cre-mediated recombination, using a ubiquitously active Rosa26-Cre line, resulted in the deletion of the floxed region in the mouse genome. Mice homozygous for the recombinant allele (HtrA4^−/−) were viable, fertile and appeared to be normal. The HtrA4 protein was detectable in coronary vessels and in the placenta. However, the loss of HtrA4 affected neither the basic heart nor placental functions. These mice, featuring a conditional null allele of HtrA4, may provide a valuable tool to investigate the role of HtrA4 in development and pathogenesis of coronary heart disease and preeclampsia.

Heat stress response of male germ cells

The vast majority of mammalian testes are located outside the body cavity for proper thermoregulation. Heat has an adverse effect on mammalian spermatogenesis and eventually leads to sub- or infertility. Recent studies have provided insights into the molecular response of male germ cells to high temperatures. Here, we review the effects of heat on male germ cells and discuss the mechanisms underlying germ cell loss and impairment. We also discuss the role of translational control in male germ cells as a potential protective mechanism against heat-induced germ cell apoptosis.

Studies of cryptorchidism in experimental animal models

Undescended testes are the most common inborn anomaly in boys but our understanding of the causes is still sparse. Experimental models of cryptorchidism in various species of animals have been used by many investigators in order to gain a better understanding of the aetiology, pathophysiology and potential treatment of the disorder. This review presents what has been gained so far by studies using experimental animal models of cryptorchidism.

CONCLUSIONS

Early orchidopexy in experimentally cryptorchid animals of different species prevents, at least partially, against testicular damage and infertility. This supports an early intervention strategy in the management of cryptorchidism in humans although animal data on the correct timing of such treatment cannot be directly translated into human clinical practice due to the species differences in pre and postnatal testis maturation. Treatment with pharmacological doses of hCG has poor efficacy in experimental animals and may cause adverse effects. Thus, clinically relevant doses of hCG causes acute inflammation-like changes in rodent testes and there are also indications that it may induce morphologically detectable permanent testicular damage.