Purification, molecular cloning and functional characterization of swine phosphatidylethanolamine-binding protein 4 from seminal plasma

Knockout of phosphatidylethanolamine binding protein4 (PEBP4) promotes chronic non-bacterial prostatitis by mediating the activation of NF-κB signaling

BACKGROUND

The etiology of chronic prostatitis remains unclear; consequently, this disease is associated with recurrence and ineffective clinical therapy. Therefore, there is an urgent need to investigate the underlying pathogenesis of chronic prostatitis in order to develop more efficacious treatments.

OBJECTIVE

The previous study found that knocking out of PEBP4 leads to chronic prostatitis in the male mice. This research aimed to identify the role of PEBP4 in prostatitis, determine the molecular pathogenic mechanisms associated with chronic prostatitis, and provide guidelines for the development of new treatment strategies for chronic prostatitis.

MATERIALS AND METHODS

A PEBP4 exon knockout strain (PEBP4-/-) was established in C57BL/6 mice via the Cre-loxP system. Hematoxylin-eosin (H&E) staining was used to investigate histological changes. RNA-sequencing was used to investigate the gene expression signature of the prostate and the levels of inflammatory cytokines were determined by real-time polymerase chain reaction (RT-PCR). The expression of PEBP4 protein in prostate tissue was determined by immunohistochemistry in specimens from patients with BPH and BPH combined with chronic prostatitis. Finally, we used a CRISPR-Cas9 plasmid to knockout PEBP4 in RWPE-1 cells; western blotting was subsequently used to measure the level of activation in the NF-κB signaling pathway after activating with TNF-α.

RESULTS

Hemorrhage and inflammatory cell infiltration were incidentally observed in the seminal vesicles and prostate glands of PEBP4-/- mice after being fed with a normal diet for 1 year. In addition, we found significantly lower (p < 0.001) expression levels of PEBP4 protein in prostate tissues from patients with benign prostate hyperplasia (BPH) and chronic and non-bacterial prostatitis (CNP) when compared to those with BPH only. The reduced expression of PEBP4 led to a higher risk of prostatitis recurrence in patients after 2 years of follow-up. Increased levels of NF-κB and IκB phosphorylation were observed in PEBP4-knockout RWPE-1 cells and prostate glands from PEBP4-/- mice.

CONCLUSION

The knockout of PEBP4 in experimental mice led to chronic prostatitis and the reduced expression of PEBP4 in patients with higher risk of chronic and non-bacterial prostatitis suggested that PEBP4 might act as a protective factor against chronic prostatitis. The knockout of PEBP4 in RWPE-1 cells led to the increased activation of NF-κB and IκB, thus indicating that inhibition of PEBP4 faciliated the NF-κB signaling cascade. Our findings provide a new etiology and therapeutic target for chronic prostatitis.

Assessing Bovine Male Fertility in a Technological Age

New and emerging technologies allow for a deeper and more comprehensive understanding of sperm physiology that can be harnessed to improve bull fertility selection. This chapter focuses on (1) the use of conventional and emerging flow cytometry techniques to further enhance functional sperm assessments; (2) new developments in proteomic and metabolomic biomarkers of bull fertility and how they can better inform fertility evaluations; and (3) the use of sperm selection technologies to optimize the fertility outcomes of bulls in artificial insemination service. As our knowledge of sperm physiology continues to expand, technology will allow for a faster translational capacity and continuous development of techniques. The technologies and techniques presented are current tools that can be used to enhance the efficiency, precision and accuracy of bull fertility assessments and better inform herd management.

Age-dependent variations in proteomic characteristics of spermatozoa in Simmental bull

Increasing the age of bulls results in a decrease in reproductive function, including a reduction in sperm quality, which plays a vital role in determining the fertility of bulls. Through a proteomic approach, this research aims to analyze the influence of age factors on various proteomes contained in bull sperm. Frozen semen samples from Simmental Bulls were categorized into three age groups: two, four, and ≥10 years old. Subsequently, the post-thaw sperm cells obtained were separated based on molecular weight using 1D-SDS-PAGE. Peptides extracted from the bands produced in each age group were subjected to LC-MS/MS analysis. A total of 72 protein types were identified, with 45 being detected in the 4-year-old group and 41 expressed in both the 2 and ≥10-year-old groups. The results provided insights into proteins' role in sperm metabolism across all age groups. Specifically, the 2-year-old group exhibited the expression of proteins associated with acrosome assembly and spermatid development (SPACA1). In contrast, those in the 4-year-old group were linked to motility (PEBP4) and sperm decapacitation factor (PEBP1). Proteins expressed in the 2 and -year-old groups were discovered to be involved in fertilization processes (TEX101). In contrast, the ≥10-year-old age group was associated with hyperactive movement related to capacitation (Tubulin). In conclusion, age influenced the differences observed in the proteomic profile of post-thaw Simmental bull sperm using the 1D-SDS-PAGE tandem LC-MS/MS approach.

PEBP4 deficiency aggravates LPS-induced acute lung injury and alveolar fluid clearance impairment via modulating PI3K/AKT signaling pathway

Acute lung injury (ALI) is a common clinical syndrome, which often results in pulmonary edema and respiratory distress. It has been recently reported that phosphatidylethanolamine binding protein 4 (PEBP4), a basic cytoplasmic protein, has anti-inflammatory and hepatoprotective effects, but its relationship with ALI remains undefined so far. In this study, we generated PEBP4 knockout (KO) mice to investigate the potential function of PEBP4, as well as to evaluate the capacity of alveolar fluid clearance (AFC) and the activity of phosphatidylinositide 3-kinases (PI3K)/serine-theronine protein kinase B (PKB, also known as AKT) signaling pathway in lipopolysaccharide (LPS)-induced ALI mice models. We found that PEBP4 deficiency exacerbated lung pathological damage and edema, and increased the wet/dry weight ratio and total protein concentration of bronchoalveolar lavage fluid (BALF) in LPS-treated mice. Meanwhile, PEBP4 KO promoted an LPS-induced rise in the pulmonary myeloperoxidase (MPO) activity, serum interleuin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α levels, and pulmonary cyclooxygenase-2 (COX-2) expression. Mechanically, PEBP4 deletion further reduced the protein expression of Na+ transport markers, including epithelial sodium channel (ENaC)-α, ENaC-γ, Na,K-ATPase α1, and Na,K-ATPase β1, and strengthened the inhibition of PI3K/AKT signaling in LPS-challenged mice. Furthermore, we demonstrated that selective activation of PI3K/AKT with 740YP or SC79 partially reversed all of the above effects caused by PEBP4 KO in LPS-treated mice. Altogether, our results indicated the PEBP4 deletion has a deterioration effect on LPS-induced ALI by impairing the capacity of AFC, which may be achieved through modulating the PI3K/AKT pathway.

Investigating in vivo Mycobacterium avium subsp. paratuberculosis microevolution and mixed strain infections

Mycobacterium avium subsp. paratuberculosis (MAP) causes Johne's Disease (JD) in ruminants, which is responsible for significant economic loss to the global dairy industry. Mixed strain infection (MSI) refers to the concurrent infection of a susceptible host with genetically distinct strains of a pathogen, whereas within-host changes in an infecting strain leading to genetically distinguishable progeny is called microevolution. The two processes can influence host-pathogen dynamics, disease progression and outcomes, but not much is known about their prevalence and impact on JD. Therefore, we obtained up to 10 MAP isolates each from 14 high-shedding animals and subjected them to whole-genome sequencing. Twelve of the 14 animals examined showed evidence for the presence of MSIs and microevolution, while the genotypes of MAP isolates from the remaining two animals could be attributed solely to microevolution. All MAP isolates that were otherwise isogenic had differences in short sequence repeats (SSRs), of which SSR1 and SSR2 were the most diverse and homoplastic. Variations in SSR1 and SSR2, which are located in ORF1 and ORF2, respectively, affect the genetic reading frame, leading to protein products with altered sequences and computed structures. The ORF1 gene product is predicted to be a MAP surface protein with possible roles in host immune modulation, but nothing could be inferred regarding the function of ORF2. Both genes are conserved in Mycobacterium avium complex members, but SSR1-based modulation of ORF1 reading frames seems to only occur in MAP, which could have potential implications on the infectivity of this pathogen. IMPORTANCE Johne's disease (JD) is a major problem in dairy animals, and concerns have been raised regarding the association of Mycobacterium avium subsp. paratuberculosis (MAP) with Crohn's disease in humans. MAP is an extremely slow-growing bacterium with low genome evolutionary rates. Certain short sequence repeats (SSR1 and SSR2) in the MAP chromosome are highly variable and evolve at a faster rate than the rest of the chromosome. In the current study, multiple MAP isolates with genetic variations such as single-nucleotide polymorphisms, and more noticeably, diverse SSRs, could simultaneously infect animals. Variations in SSR1 and SSR2 affect the products of the respective genes containing them. Since multiple MAP isolates can infect the same animal and the possibility that the pathogen undergoes further changes within the host due to unstable SSRs, this could provide a compensative mechanism for an otherwise slow-evolving pathogen to increase phenotypic diversity for overcoming host responses.

PEBP4 Directs the Malignant Behavior of Hepatocellular Carcinoma Cells via Regulating mTORC1 and mTORC2

Phosphatidylethanolamine binding protein 4 (PEBP4) is an understudied multifunctional small protein. Previous studies have shown that the expression of PEBP4 is increased in many cancer specimens, which correlates to cancer progression. The present study explored the mechanism by which PEBP4 regulates the growth and progression of hepatocellular carcinoma cells. Thus, we showed that knockdown of PEBP4 in MHCC97H cells, where its expression was relatively high, diminished activities of serine/threonine protein kinase B (PKB, also known as Akt), mammalian target of rapamycin complex 1(mTORC1), and mTORC2, events that were not restored by insulin-like growth factor 1 (IGF-1). Conversely, overexpression of PEBP4 in MHCC97L cells with the low endogenous level yielded opposite effects. Furthermore, physical association of PEBP4 with Akt, mTORC1, and mTORC2 was observed. Interestingly, introduction of AktS473D mutant, bypassing phosphorylation by mTORC2, rescued mTORC1 activity, but without effects on mTORC2 signaling. In contrast, the effect of PEBP4 overexpression on the activity of mTORC1 but not that of mTORC2 was suppressed by MK2206, a specific inhibitor of Akt. In conjunction, PEBP4 knockdown-engendered reduction of cell proliferation, migration and invasion was partially rescued by Akt S473D while increases in these parameters induced by overexpression of PEBP4 were completely abolished by MK2206, although the expression of epithelial mesenchymal transition (EMT) markers appeared to be fully regulated by the active mutant of Akt. Finally, knockdown of PEBP4 diminished the growth of tumor and metastasis, whereas they were enhanced by overexpression of PEBP4. Altogether, our study suggests that increased expression of PEBP4 exacerbates malignant behaviors of hepatocellular cancer cells through cooperative participation of mTORC1 and mTORC2.

Immuno-histological mapping and functional association of seminal proteins in testis and excurrent ducts with sperm function in buffalo

The region-specific expression of seminal proteins in testis and excurrent duct system determines the quality and function of the spermatozoa. In the present study, localization and expression of some of the seminal proteins such as insulin-like growth factor receptor 1β (IGF-1Rβ), phosphatidylethanolamine-binding protein 4 (PEBP4), α-tubulin and tissue factor pathway inhibitor 2 (TFPI2) were carried out in testis, excurrent duct system and spermatozoa of buffalo. IGF-1Rβ was localized in the cells of the seminiferous tubules of the testis, except in primary spermatocytes. The PEBP4 was localized only in the elongated spermatid, whereas α-tubulin and TFPI2 proteins were localized in all cells of the seminiferous tubule including spermatocyte. In the buffalo spermatozoa, IGF-1Rβ, PEBP4, α-tubulin and TFPI2 were localized in the acrosome region, the post-acrosomal region till the tail end, post-acrosome to the entire tail region and the equatorial region, respectively. The study indicates that IGF-1R, α-tubulin and PEBP4 proteins regulate spermatogenesis, whereas TFPI2 may be involved during the zona binding process of the buffalo spermatozoa.

PEBP4 gene expression in lung squamous cell carcinoma: A meta-analysis-based study of the molecular pathways involved

Previous studies have suggested increased activity of phosphatidylethanolamine binding protein 4 (PEBP4) may be associated with the prognosis of non-small cell lung cancer. However, to the best of our knowledge, no direct association between PEBP4 and lung squamous cell carcinoma (LSCC) has been reported. In the present study, a systematic review and meta-analysis was performed to examine the gene expression activity of PEBP4 in LSCC. A total of 10 out of 131 gene expression datasets from the Gene Expression Omnibus (GEO) were selected, including 574 samples (319 patients with LSCC and 255 healthy controls). Subsequently, multiple linear regression (MLR) was employed to study three potential influencing factors: Sample size, population region and study date. A literature-based pathway analysis was then conducted to examine the potential mechanisms through which PEBP4 may exert influence on LSCC. The results of a meta-analysis indicated that, in LSCC, PEBP4 exhibited significantly low expression levels (P<0.033), with mildly increased gene expression levels observed in three studies (log fold-change: 0.072–2.13). However, a significant between-study variance was observed from the heterogeneity analysis. MLR indicated that population region was a significant factor (P<0.0065), whereas sample size and study age were not (P>0.46). Eight functional pathways were subsequently identified, through which PEBP4 may influence the prognosis of LSCC and its response to treatment. The results of the present study suggested that the effects of PEBP4 on LSCC can be neglected in most cases of LSCC, where PEBP4 demonstrated decreased expression levels. However, in the case of PEBP4 overexpression, it may contribute to the progression of LSCC and lead to the development of drug resistance.

Proteome of cat semen obtained after urethral catheterization

The binding of seminal plasma (SP) proteins by spermatozoa plays an important role in the regulation of sperm epididymal maturation, motility gaining in female reproductive tracts and sperm-egg interaction. The aim of the study was to analyze the SP and sperm extracts proteome of cat (Felis catus) semen. The seminal plasma and spermatozoa were obtained by urethra catheterization from 10 male cats. Proteins were extracted using RIPA buffer and separated by electrophoresis (SDS-PAGE). The gels were analyzed using MultiAnalyst software. The proteins were subsequently analyzed using NanoUPLC-Q-TOF/MS. UniProt database-supported identification resulted in 106 proteins identified in the cat SP and 98 proteins in the extracts of spermatozoa. Based on a gene ontology analysis, dominant molecular functions of feline SP proteins were binding, catalytic, and antioxidant activity (56%, 33%, and 11% of cases, respectively). The molecular functions of sperm extracts proteins were mainly involved in catalytic activity (41%) and binding (23%). The proteins present in both, the SP and spermatozoa's extracts, were: serum albumin (ALB), semenogelin 2 (SEMG 2), clusterin (CLU), lactoferrin (LTF), prostatic acid phosphatase (ACPP), prolactin inducible protein (PIP), negative elongation factor E (NELF-E) and ectonucleotide pyrophosphatase (ENPP3). Protein-protein interactions analysis showed significant connection for 12 proteins in the cat semen. The seminal plasma proteins which, with high probability score, participate in important metabolic pathways are: glutathione peroxidases (GPx5 and 6), prostatic acid phosphatase (ACPP), β-hexosaminidase (HEXB), polymeric immunoglobulin receptor (pIgR) and serpin family F member 1 (SERPINF1). For sperm protein extracts it were: pyruvate dehydrogenase (PDHB), succinate-CoA-ligase (SUCLA2), malate dehydrogenase (MDH2), ATP synthase F1 subunit alpha (ATP5F1A) and tubulin beta (TUBB).

Differential gene expression in porcine oviduct during the oestrous cycle

The oviduct undergoes changes under the influence of steroid hormones during the oestrous cycle. However, the molecular mechanisms underlying oviductal regulation are not fully understood. The aim of the present study was to identify the gene expression profile of the porcine oviduct in different stages of the cycle using microarray technology. A systematic study was performed on animals at four different stage: prepubertal gilts, and sows in the preovulatory, postovulatory and luteal phase of the oestrous cycle. The porcine oviduct expressed a total of 4929 genes. Moreover, significant differences in the expression of several genes were detected as the oestrous cycle progressed. Analysis of the differentially expressed genes indicated that a total of 86, 89 and 15 genes were upregulated in prepubertal gilts, preovulatory and luteal sows respectively compared with levels observed in postovulatory sows. Moreover, 80, 51 and 64 genes were downregulated in prepubertal, preovulatory and luteal animals respectively compared with the postovulatory sows. The concentrations of 10 selected transcripts were quantified by real-time reverse transcription–polymerase chain reaction to validate the cDNA array hybridisation data. Conversely, for some genes, localisation of corresponding protein expression in the oviduct was analysed by immunohistochemistry (i.e. cholecystokinin, glutathione peroxidase 2, mucin 1, phosphatidylethanolamine binding protein 4 and tachykinin 3) and mass spectrometry analysis of oviductal fluid allowed identification of peptides from all five proteins. The results of the present study demonstrate that gene expression in the porcine oviduct is clearly regulated during the oestrous cycle, with some oviductal proteins that could be related to several reproductive processes described here for the first time.

Phosphatidylethanolamine binding protein 4 (PEBP4) is a secreted protein and has multiple functions

Phosphatidylethanolamine binding proteins (PEBP) represent a superfamily of proteins that are conserved from bacteria to humans. In mammals, four members have been identified, PEBP1-4. To determine the functional differences among PEBP1-4 and the underlying mechanism for their actions, we performed a sequence alignment and found that PEBP4 contains a signal peptide and potential glycosylation sites, whereas PEBP1-3 are intracellular proteins. To test if PEBP4 is secreted, we made constructs with Myc epitope at the amino (N) terminus or carboxyl (C) terminus to mask the signal sequence or keep it free, respectively. Our data revealed that both mouse and human PEBP4 were secreted when the epitope was tagged at their C-terminus. To our surprise, secretion was dependent upon the C-terminal conserved domain in addition to the N-terminal signal sequence. When the epitope was placed to the N-terminus, the recombinant protein failed to secrete and instead, was retained in the cytoplasm. Mass spectrometry detected asparagine (N)-glycosylation on the secreted PEBP4. Although overexpression of N-terminal tagged PEBP4 resulted in an inhibition of ERK activation by EGF, that with a C-terminal epitope tag did not have such an effect. Likewise, transfection of PEBP4 shRNA did not appear to affect ERK activation, suggesting that PEBP4 does not participate in the regulation of this pathway. In contrast, PEBP4 siRNA suppressed phosphorylation of Act at S473. Therefore, our results suggest that PEBP4 is a multifunctional protein and can be secreted. It will be important to investigate the mechanism by which PEBP4 is secreted and regulates cellular events.

Domain 5 of high molecular weight kininogen inhibits collagen-mediated cancer cell adhesion and invasion in association with α-actinin-4

High molecular weight kininogen (HK) is a plasma glycoprotein with multiple functions, including the regulation of coagulation. We previously demonstrated that domain 5 (D5(H)), a functional domain of HK, and its derived peptides played an important role in the vitronectin-mediated suppression of cancer cell adhesion and invasion. However, the underlying mechanisms of the D5(H)-mediated suppressive effects remain to be elucidated. Here, we showed that D5(H) and its derivatives inhibited the collagen-mediated cell adhesion and invasion of human osteosarcoma MG63 cells. Using purified D5(H) fused to glutathione-S-transferase (GST) and D5(H)-derived peptides for column chromatography, an actin-binding protein, α-actinin-4, was identified as a binding protein of D5(H) with high-affinity for P-5m, a core octapeptide of D5(H). Immunofluorescence microscopy demonstrated that D5(H) co-localized with α-actinin-4 inside MG63 cells. In addition, exogenous GST-D5(H) added to the culture media was transported into MG63 cells, although GST alone as a control was not. As α-actinin-4 regulates actin polymerization necessary for cell adhesion and is related to the integrin-dependent attachment of cells to the extracellular matrix, our results suggest that D5(H) may modulate cell adhesion and invasion together with actinin-4.