Peibei Sun

Bio: Peibei Sun is an academic researcher from Peking Union Medical College. The author has contributed to research in topics: Sperm & Capacitation. The author has an hindex of 3, co-authored 7 publications receiving 20 citations.

Hsp90 modulates human sperm capacitation via the Erk1/2 and p38 MAPK signaling pathways.

Abstract: Heat shock protein 90 (Hsp90) is a highly abundant eukaryotic molecular chaperone that plays important roles in client protein maturation, protein folding and degradation, and signal transduction Previously, we found that both Hsp90 and its co-chaperone cell division cycle protein 37 (Cdc37) were expressed in human sperm Hsp90 is known to be involved in human sperm capacitation via unknown underlying mechanism(s) As Cdc37 was a kinase-specific co-chaperone of Hsp90, Hsp90 may regulate human sperm capacitation via other kinases It has been reported that two major mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinase 1/2 (Erk1/2) and p38, are expressed in human sperm in the same locations as Hsp90 and Cdc37 Phosphorylated Erk1/2 has been shown to promote sperm hyperactivated motility and acrosome reaction, while phosphorylated p38 inhibits sperm motility Therefore, in this study we explored whether Hsp90 modulates human sperm capacitation via the Erk1/2 and p38 MAPK signaling pathways Human sperm was treated with the Hsp90-specific inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) during capacitation Computer-assisted sperm analyzer (CASA) was used to detect sperm motility and hyperactivation The sperm acrosome reaction was analyzed by using fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (PSA-FITC) staining The interactions between Hsp90, Cdc37, Erk1/2 and p38 were assessed using co-immunoprecipitation (Co-IP) experiments Western blotting analysis was used to evaluate the levels of protein expression and phosphorylation Human sperm hyperactivation and acrosome reaction were inhibited by 17-AAG, suggesting that Hsp90 is involved in human sperm capacitation In addition, Co-IP experiments revealed that 17-AAG reduced the interaction between Hsp90 and Cdc37, leading to the dissociation of Erk1/2 from the Hsp90-Cdc37 protein complex Western blotting analysis revealed that levels of Erk1/2 and its phosphorylated form were subsequently decreased Decreasing of Hsp90-Cdc37 complex also affected the interaction between Hsp90 and p38 Nevertheless, p38 dissociated from the Hsp90 protein complex and was activated by autophosphorylation Taken together, our findings indicate that Hsp90 is involved in human sperm hyperactivation and acrosome reaction In particular, Hsp90 and its co-chaperone Cdc37 form a protein complex with Erk1/2 and p38 to regulate their kinase activity These results suggest that Hsp90 regulates human sperm capacitation via the Erk1/2 and p38 MAPK signaling pathways

Hsp90 interacts with Cdc37, is phosphorylated by PKA/PKC, and regulates Src phosphorylation in human sperm capacitation.

Abstract: Background Heat shock protein 90 (Hsp90) signaling pathways participate in protein phosphorylation during sperm capacitation. However, the underlying mechanism is largely unknown. Objective The aim of this study was to explore the interaction between Hsp90 and its co-chaperone protein, cell division cycle protein Cdc37 (Cdc37), in human spermatozoa. Materials and methods We examined the effects of H-89 (a protein kinase A [PKA] inhibitor) and Go6983 (a protein kinase C [PKC] inhibitor) on the phosphorylation of serine, threonine, and tyrosine residues in Hsp90; the effect of 17-allylamino-17-demethoxygeldanamycin (17-AAG, Hsp90 inhibitor) on Y416-Src phosphorylation; and the effects of 17-AAG and geldanamycin on threonine phosphorylation during human sperm capacitation. Results Hsp90 co-localized and interacted with Cdc37. During human sperm capacitation, Hsp90 phosphorylation at serine, threonine, and tyrosine residues was inhibited by H-89 and Go6983. In addition, phosphorylation of residue Y416 in the tyrosine kinase Src (its active site) was inhibited by 17-AAG, and the threonine phosphorylation levels of some proteins were decreased by 17-AAG and geldanamycin. Discussion and conclusion Taken together, our data showed that the interaction of Hsp90 with Cdc37 regulates total protein threonine phosphorylation and Src phosphorylation via its serine, threonine, and tyrosine phosphorylation, which are controlled by PKA and PKC during human sperm capacitation. The results of this study help understand the mechanism underlying Hsp90 regulation of sperm function.

Novel distance-progesterone-combined selection approach improves human sperm quality.

Abstract: Sperm selection is essential for the health of offspring conceived via assistive reproductive technology (ART) Various methods of sperm preparation for in vitro fertilization and intracytoplasmic sperm injection have been developed to acquire sperm with better quality and to avoid potential genetic disorders However, current sperm processing and selection techniques bypass the natural selection that occurs during fertilization in vivo The aim of this study was to present a novel distance-progesterone-combined selection approach with an original device based on the human female reproductive tract, and to report on its effectiveness based on sperm progressive motility, as well as chemotaxis A novel device with long distance channels which mimicked the female human reproductive system was designed and fabricated This ready-to-be-used device was developed using a progesterone gradient and human tube fluid media Sperm swam for 150 min in the device under conditions of 37 °C air temperature with 5% CO2 after separation from seminal plasma via discontinuous Percoll gradient treatment The selected sperm were assessed for normal morphology using Diff-Quik staining A chromatin diffusion assay assessed sperm for DNA fragments and apoptosis was assessed using annexin V-fluorescein isothiocyanate/propidium iodide fluorescent staining Our distance-progesterone-combined sperm selection method was successfully established After sperm were selected, the percentage of sperm with normal morphology increased (before vs after selection, 112 ± 13% vs 403 ± 66%, P = 0000), the percentage of sperm with DNA fragmentation decreased (before vs after selection, 154 ± 40% vs 68 ± 33%, P = 0001), and the percentage of sperm with apoptosis did not change significantly Our newly-developed method is capable of successfully selecting sperm of high quality The method will be benefit clinical ART practice as it can reduce sperm-related genetic risks

KCNQ1 Potassium Channel Expressed in Human Sperm Is Involved in Sperm Motility, Acrosome Reaction, Protein Tyrosine Phosphorylation, and Ion Homeostasis During Capacitation.

Abstract: Potassium channels are involved in membrane hyperpolarization and ion homeostasis regulation during human sperm capacitation. However, the types of potassium channels in human sperm remain controversial. The voltage-gated ion channel KCNQ1 is ubiquitously expressed and regulates key physiological processes in the human body. In the present study, we investigated whether KCNQ1 is expressed in human sperm and what role it might have in sperm function. The expression and localization of KCNQ1 in human sperm were evaluated using Western blotting and indirect immunofluorescence. During capacitation incubation, human sperm were treated with KCNQ1- specific inhibitor chromanol 293B. Sperm motility was analyzed using a computer-assisted sperm analyzer. The acrosome reaction was studied using fluorescein isothiocyanate-conjugated Pisum sativum agglutinin staining. Protein tyrosine phosphorylation levels and localization after capacitation were determined using Western blotting and immunofluorescence. Intracellular K+, Ca2+, Cl-, pH, and membrane potential were analyzed using fluorescent probes. The results demonstrate that KCNQ1 is expressed and localized in the head and tail regions of human sperm. KCNQ1 inhibition reduced sperm motility, acrosome reaction rates, and protein tyrosine phosphorylation but had no effect on hyperactivation. KCNQ1 inhibition also increased intracellular K+, membrane potential, and intracellular Cl-, while decreasing intracellular Ca2+ and pH. In conclusion, the KCNQ1 channel plays a crucial role during human sperm capacitation.

MicroRNAs: Target Recognition and Regulatory Functions

Abstract: MicroRNAs (miRNAs) are endogenous ∼23 nt RNAs that play important gene-regulatory roles in animals and plants by pairing to the mRNAs of protein-coding genes to direct their posttranscriptional repression. This review outlines the current understanding of miRNA target recognition in animals and discusses the widespread impact of miRNAs on both the expression and evolution of protein-coding genes.

Novel Techniques of Sperm Selection for Improving IVF and ICSI Outcomes.

Abstract: Almost 50% of the infertility cases are due to male factors. Assisted reproductive technologies (ARTs) allow to overcome the incapacity of these patients' spermatozoa to fertilize the oocyte and produce a viable and healthy offspring, but the efficiency of the different techniques has still the potential to improve. According to the latest reports of the European Society of Human Reproduction and Embryology (ESHRE) and the Centers for Disease Control and Prevention of the United States (CDC), the percentages of deliveries per ART cycle in 2014 and 2016 were 21 and 22%, respectively. Among the reasons for this relatively low efficiency, the quality of the spermatozoa has been pointed out as critical, and the presence of high percentages of DNA-damaged spermatozoa in patients' ejaculates is possibly one of the main factors reducing the ARTs outcomes. Thus, one of the main challenges in reproductive medicine is to ensure the highest quality of the spermatozoa used in ARTs, and specifically, in terms of genetic integrity. The latest techniques for the preparation and selection of human spermatozoa are herein discussed focusing on those proven to improve one or several of the following parameters: sperm genetic integrity, fertilization capacity, embryo production, and in vitro survival, as well as pregnancy and delivery rates following in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). In addition, we discuss the potential of techniques developed in non-human mammals that could be further transferred to the clinic.

Quantitative Analysis of Hsp90-Client Interactions Reveals Principles of Substrate Recognition

Abstract: National Institutes of Health (U.S.). Genomics Based Drug Discovery-Driving Medical Project (Grant UL1-DE019585)

Hsp90 modulates human sperm capacitation via the Erk1/2 and p38 MAPK signaling pathways.

Abstract: Heat shock protein 90 (Hsp90) is a highly abundant eukaryotic molecular chaperone that plays important roles in client protein maturation, protein folding and degradation, and signal transduction Previously, we found that both Hsp90 and its co-chaperone cell division cycle protein 37 (Cdc37) were expressed in human sperm Hsp90 is known to be involved in human sperm capacitation via unknown underlying mechanism(s) As Cdc37 was a kinase-specific co-chaperone of Hsp90, Hsp90 may regulate human sperm capacitation via other kinases It has been reported that two major mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinase 1/2 (Erk1/2) and p38, are expressed in human sperm in the same locations as Hsp90 and Cdc37 Phosphorylated Erk1/2 has been shown to promote sperm hyperactivated motility and acrosome reaction, while phosphorylated p38 inhibits sperm motility Therefore, in this study we explored whether Hsp90 modulates human sperm capacitation via the Erk1/2 and p38 MAPK signaling pathways Human sperm was treated with the Hsp90-specific inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) during capacitation Computer-assisted sperm analyzer (CASA) was used to detect sperm motility and hyperactivation The sperm acrosome reaction was analyzed by using fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (PSA-FITC) staining The interactions between Hsp90, Cdc37, Erk1/2 and p38 were assessed using co-immunoprecipitation (Co-IP) experiments Western blotting analysis was used to evaluate the levels of protein expression and phosphorylation Human sperm hyperactivation and acrosome reaction were inhibited by 17-AAG, suggesting that Hsp90 is involved in human sperm capacitation In addition, Co-IP experiments revealed that 17-AAG reduced the interaction between Hsp90 and Cdc37, leading to the dissociation of Erk1/2 from the Hsp90-Cdc37 protein complex Western blotting analysis revealed that levels of Erk1/2 and its phosphorylated form were subsequently decreased Decreasing of Hsp90-Cdc37 complex also affected the interaction between Hsp90 and p38 Nevertheless, p38 dissociated from the Hsp90 protein complex and was activated by autophosphorylation Taken together, our findings indicate that Hsp90 is involved in human sperm hyperactivation and acrosome reaction In particular, Hsp90 and its co-chaperone Cdc37 form a protein complex with Erk1/2 and p38 to regulate their kinase activity These results suggest that Hsp90 regulates human sperm capacitation via the Erk1/2 and p38 MAPK signaling pathways

A microfluidic approach to rapid sperm recovery from heterogeneous cell suspensions.

Abstract: The isolation of sperm cells from background cell populations and debris is an essential step in all assisted reproductive technologies. Conventional techniques for sperm recovery from testicular sperm extractions stagnate at the sample processing stage, where it can take several hours to identify viable sperm from a background of collateral cells such as white bloods cells (WBCs), red blood cells (RBCs), epithelial cells (ECs) and in some cases cancer cells. Manual identification of sperm from contaminating cells and debris is a tedious and time-consuming operation that can be suitably addressed through inertial microfluidics. Microfluidics has proven an effective technology for high-quality sperm selection based on motility. However, motility-based selection methods cannot cater for viable, non-motile sperm often present in testicular or epididymal sperm extractions and aspirations. This study demonstrates the use of a 3D printed inertial microfluidic device for the separation of sperm cells from a mixed suspension of WBCs, RBCs, ECs, and leukemic cancer cells. This technology presents a 36-fold time improvement for the recovery of sperm cells (> 96%) by separating sperm, RBCS, WBCs, ECs and cancer cells into tight bands in less than 5 min. Furthermore, microfluidic processing of sperm has no impact on sperm parameters; vitality, motility, morphology, or DNA fragmentation of sperm. Applying inertial microfluidics for non-motile sperm recovery can greatly improve the current processing procedure of testicular sperm extractions, simplifying the fertility outcomes for severe forms of male infertility that warrant the surgery.