Establishment, characterization, and application of pAcr-SP-NTP-EGFP transgenic mice in visualizing the oviduct-migrating ability of sperm from Prss37-null mice

Spem2, a novel testis-enriched gene, is required for spermiogenesis and fertilization in mice

Spermiogenesis is considered to be crucial for the production of haploid spermatozoa with normal morphology, structure and function, but the mechanisms underlying this process remain largely unclear. Here, we demonstrate that SPEM family member 2 (Spem2), as a novel testis-enriched gene, is essential for spermiogenesis and male fertility. Spem2 is predominantly expressed in the haploid male germ cells and is highly conserved across mammals. Mice deficient for Spem2 develop male infertility associated with spermiogenesis impairment. Specifically, the insufficient sperm individualization, failure of excess cytoplasm shedding, and defects in acrosome formation are evident in Spem2-null sperm. Sperm counts and motility are also significantly reduced compared to controls. In vivo fertilization assays have shown that Spem2-null sperm are unable to fertilize oocytes, possibly due to their impaired ability to migrate from the uterus into the oviduct. However, the infertility of Spem2-/- males cannot be rescued by in vitro fertilization, suggesting that defective sperm-egg interaction may also be a contributing factor. Furthermore, SPEM2 is detected to interact with ZPBP, PRSS21, PRSS54, PRSS55, ADAM2 and ADAM3 and is also required for their processing and maturation in epididymal sperm. Our findings establish SPEM2 as an essential regulator of spermiogenesis and fertilization in mice, possibly in mammals including humans. Understanding the molecular role of SPEM2 could provide new insights into future therapeutic treatment of human male infertility and development of non-hormonal male contraceptives.

Dissecting the PRSS37 interactome and potential mechanisms leading to ADAM3 loss in PRSS37-null sperm

A disintegrin and metalloproteinase 3 (ADAM3) is a sperm membrane protein critical for sperm migration from the uterus into the oviduct and sperm-egg binding in mice. Disruption of PRSS37 results in male infertility concurrent with the absence of mature ADAM3 from cauda epididymal sperm. However, how PRSS37 modulates ADAM3 maturation remains largely unclear. Here, we determine the PRSS37 interactome by GFP immunoprecipitation coupled with mass spectrometry in PRSS37-EGFP knock-in mice. Three molecular chaperones (CLGN, CALR3 and PDILT) and three ADAM proteins (ADAM2, ADAM6B and ADAM4) were identified to be interacting with PRSS37. Coincidently, five of them (except ADAM4) have been reported to interact with ADAM3 precursor and regulate its maturation. We further demonstrated that PRSS37 also interacts directly with ADAM3 precursor and its deficiency impedes the association between PDILT and ADAM3. This could contribute to improper translocation of ADAM3 to the germ cell surface, leading to ADAM3 loss in PRSS37-null mature sperm. The understanding of the maturation mechanisms of pivotal sperm plasma membrane proteins will pave the way toward novel strategies for contraception and the treatment of unexplained male infertility.

PRSS55 plays an important role in the structural differentiation and energy metabolism of sperm and is required for male fertility in mice

Orderly and stage‐specifically expressed proteins are essential for spermatogenesis, and proteases play a key role in protein activation and function. The present study aimed to investigate serine protease 55 (PRSS55), which was reported to play a role in sperm‐uterotubal junction (UTJ) migration and sperm‐zona pellucida (ZP) binding. We found that PRSS55 was specifically expressed in testicular spermatids and epididymal spermatozoa. By constructing knockout mice targeting all transcripts of Prss55, we demonstrated that deletion of Prss55 resulted in a serious decline of male fertility, with significantly increased sperm malformation and decreased sperm motility. In Prss55^−/− mice, increased structural abnormality, including deficient “9 + 2” microtubules, damaged peripheral dense fibre, and defective mitochondrial cristae, were found in sperm. In addition, sperm showed decreased expression of electron transfer chain molecules and lower ATP contents. These could be the potential causes of the astheno/teratozoospermia phenotype of the Prss55^−/− mice, and provided new evidence for the previously reported impaired sperm‐UTJ migration. Moreover, preliminary studies allowed us to speculate that PRSS55 might function by activating type II muscle myosin in the testis, which is involved in many processes requiring motivation and cytoskeleton translocation. Thus, PRSS55 is essential for the structural differentiation and energy metabolism of sperm, and might be a potential pathogenic factor in astheno/teratozoospermia. Our results provide an additional explanation for the male sterility of Prss55^−/− mice, and further reveal the role of PRSS55.

Serine protease PRSS55 is crucial for male mouse fertility via affecting sperm migration and sperm-egg binding

Testis-specific PRSS55 is a highly conserved chymotrypsin-like serine protease among mammalian species. So far, the physiological function of PRSS55 remains unknown. Here, we show that PRSS55 is a GPI-anchored membrane protein, specifically expressed in adult mouse testis and mainly observed in the luminal side of seminiferous tubules and sperm acrosome. Mice deficient for Prss55 develop male infertile with normal reproduction-related parameters observed. Interestingly, in vivo fertilization rate of Prss55^−/− males is dramatically decreased, possibly due to incapable migration of Prss55^−/− sperm from uterus into oviduct. However, in vitro fertilization rate has no difference between two genotypes although Prss55^−/− sperm presents defective recognition/binding to zona-intact or zona-free oocytes. Further study reveals that mature ADAM3 is almost undetectable in Prss55^−/− sperm, while precursor ADAM3 remains unchanged in the testis. However, it is shown that ADAM3 has no interaction with PRSS55 by immunoprecipitation with anti-PRSS55 antibody. The expression levels of several proteins known to be related to the observed phenotypes remain comparable between wt and Prss55^−/− mice. Moreover, we found that Prss55 deficiency has no effect on PRSS37 or vice versa albeit two mutant males share almost the same phenotypes. Microarray analysis reveals a total of 72 differentially expressed genes in Prss55^−/− testis, most of which are associated with cellular membrane and organelle organization, protein transport and complex assembly, and response to stimulus and signaling. In conclusion, we have demonstrated that PRSS55 plays vital roles in regulating male fertility of mice, including in vivo sperm migration and in vitro sperm–egg interaction, possibly by affecting the maturation of ADAM3 in sperm and the expression of multiple genes in testis.

A Novel S100A8/A9 Induced Fingerprint of Mesenchymal Stem Cells associated with Enhanced Wound Healing

We here investigated whether the unique capacity of mesenchymal stem cells (MSCs) to re-establish tissue homeostasis depends on their potential to sense danger associated molecular pattern (DAMP) and to mount an adaptive response in the interest of tissue repair. Unexpectedly, after injection of MSCs which had been pretreated with the calcium-binding DAMP protein S100A8/A9 into murine full-thickness wounds, we observed a significant acceleration of healing even exceeding that of non-treated MSCs. This correlates with a fundamental reprogramming of the transcriptome in S100A8/A9 treated MSCs as deduced from RNA-seq analysis and its validation. A network of genes involved in proteolysis, macrophage phagocytosis, and inflammation control profoundly contribute to the clean-up of the wound site. In parallel, miR582-5p and genes boosting energy and encoding specific extracellular matrix proteins are reminiscent of scar-reduced tissue repair. This unprecedented finding holds substantial promise to refine current MSC-based therapies for difficult-to-treat wounds and fibrotic conditions.

Ablation of Tacr2 in mice leads to gastric emptying disturbance

BACKGROUND

Tacr2 is one of the G protein-coupled receptors(GPCRs) that mediate the biological actions of tachykinins. It is abundantly expressed in the gastrointestinal (GI) system and is thought to play an important role in GI motility, secretion, and visceral sensitivity. Previously, the physiological and pathophysiological functions of Tacr2 were mainly studied using Tacr2 selective agonists or antagonists. Here, we seek to investigate the effect of Tacr2 disruption in mice to provide further insights.

METHODS

The Tacr2 knockout mice were generated by homologous recombination and the phenotypic changes of the Tacr2-null mice were analyzed and compared with their wild type (wt) littermates.

KEY RESULTS

Increased food retention was detected in Tacr2^-/- mice. The stomach of Tacr2^-/- mice had thinner muscularis externa and less neurons in the myenteric plexus. The stomach and small intestine exhibited longer duration of electrical field stimulation (EFS)-induced inhibition in the gastric fundus and decreased frequency of migrating motor complex (MMC), respectively. Neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP) were significantly up-regulated due to Tarc2 deficiency, contributing to enhanced nitric oxide (NO) signaling in the stomach of Tacr2^-/- mice. Intraperitoneal application of 7-nitroindazole (7-NI) to Tacr2^-/- mice effectively relieved the gastric emptying disturbance. Moreover, Creb and NF-κB signalings were involved in the regulation of these physiological changes initiated by Tacr2 deficiency.

CONCLUSIONS & INFERENCES

Tacr2 negatively regulated the expression of nNOS and VIP both in vivo and in vitro. Its ablation in mice elevated the expression of nNOS and VIP, enhanced NO signaling and changed the Creb and NF-κB signalings, finally leading to the gastric emptying disturbance of Tacr2^-/- mice.