Blood-testis barrier: a review on regulators in maintaining cell junction integrity between Sertoli cells

The blood-testis barrier (BTB) is formed adjacent to the seminiferous basement membrane. It is a distinct ultrastructure, partitioning testicular seminiferous epithelium into apical (adluminal) and basal compartments. It plays a vital role in developing and maturing spermatocytes into spermatozoa via reorganizing its structure. This enables the transportation of preleptotene spermatocytes across the BTB, from basal to adluminal compartments in the seminiferous tubules. Several bioactive peptides and biomolecules secreted by testicular cells regulate the BTB function and support spermatogenesis. These peptides activate various downstream signaling proteins and can also be the target themself, which could improve the diffusion of drugs across the BTB. The gap junction (GJ) and its coexisting junctions at the BTB maintain the immunological barrier integrity and can be the "gateway" during spermatocyte transition. These junctions are the possible route for toxicant entry, causing male reproductive dysfunction. Herein, we summarize the detailed mechanism of all the regulators playing an essential role in the maintenance of the BTB, which will help researchers to understand and find targets for drug delivery inside the testis.

Bioinformatic Analysis of the BTB Gene Family in Paulownia fortunei and Functional Characterization in Response to Abiotic and Biotic Stresses

To learn about the gene structure, phylogenetic evolution, and function under biotic and abiotic stresses of BTB (Bric-a-Brac/Tramtrack/Broad Complex) genes in Paulownia fortunei, a whole-genome sequence evaluation was carried out, and a total of 62 PfBTB genes were identified. The phylogenetic analysis showed that PfBTB proteins are divided into eight groups, and these proteins are highly conserved. PfBTB genes were unevenly distributed on 17 chromosomes. The colinearity analysis found that fragment replication and tandem replication are the main modes of gene amplification in the PfBTB family. The analysis of cis-acting elements suggests that PfBTB genes may be involved in a variety of biological processes. The transcriptomic analysis results showed that PfBTB3/12/14/16/19/36/44 responded to Paulownia witches' broom (PaWB), while PfBTB1/4/17/43 responded to drought stress, and the RT-qPCR results further support the reliability of transcriptome data. In addition, the association analysis between miRNA and transcriptome revealed a 91-pair targeting relationship between miRNAs and PfBTBs. In conclusion, the BTB genes in Paulownia are systematically identified in this research. This work provides useful knowledge to more fully appreciate the potential functions of these genes and their possible roles in the occurrence of PaWB and in response to stress.

The Effect of Lateral Extra-articular Tenodesis in an ACL-Reconstructed Knee With Partial Medial Meniscectomy: A Biomechanical Study

BACKGROUND

Knee laxity increases with medial meniscectomy in anterior cruciate ligament (ACL)-reconstructed knees; however, the biomechanical effect of an additional lateral extra-articular tenodesis (LET) is unknown.

PURPOSE/HYPOTHESIS

The purpose of this study was to determine the kinematic effect of a LET in knees that underwent combined ACL reconstruction (ACL-R) and partial medial meniscus posterior horn (MMPH) meniscectomy. It was hypothesized that the addition of LET would reduce laxity in the ACL-reconstructed knee.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten fresh-frozen human cadaveric knees (mean age, 41.5 years) were tested using a robotic system under 3 loads: (1) 89.0 N of anterior tibial (AT) load, (2) 5 N·m of internal rotation (IR) tibial torque, and (3) a simulated pivot shift-a combined valgus of 7 N·m and IR torque of 5 N·m-at 0°, 15°, 30°, 45°, 60°, and 90° of knee flexion. Kinematic data were acquired in 4 states: (1) intact, (2) ACL-R, (3) ACL-R + partial MMPH meniscectomy (MMPH), and (4) ACL-R + partial MMPH meniscectomy + LET (MMPH+LET).

RESULTS

In response to AT loading, there was a significant increase seen in AT translation (ATT) in the MMPH state at all knee flexion angles compared with the ACL-R state, with the highest increase at 90° of knee flexion (mean difference, 3.1 mm) (P < .001). Although there was a significant decrease in ATT at 15° of knee flexion with MMPH+LET (P = .022), no significant differences were found at other knee flexion angles (P > .05). In MMPH with IR torque, a significant increase was observed in IR at all knee flexion angles except 90° compared with the ACL-R state (range, 2.8°-4.9°), and this increase was significantly decreased at all flexion angles with the addition of LET (range, 0.7°-1.6°) (P < .05).

CONCLUSION

Performing a partial MMPH meniscectomy increased ATT and IR in response to AT and IR loads compared with the isolated ACL-R state in a cadaveric model. However, when the LET procedure was performed after partial MMPH meniscectomy, a significant decrease was seen at all knee flexion angles except 90° in response to IR and torque, and a significant decrease was seen at 15° of knee flexion in response to AT load.

CLINICAL RELEVANCE

LET may be a useful adjunct procedure after ACL-R with partial MMPH meniscectomy to reduce knee laxity.

Structural and biochemical characterization establishes a detailed understanding of KEAP1-CUL3 complex assembly

KEAP1 promotes the ubiquitin-dependent degradation of NRF2 by assembling into a CUL3-dependent ubiquitin ligase complex. Oxidative and electrophilic stress inhibit KEAP1 allowing NRF2 to accumulate for the transactivation of stress response genes. To date there are no structures of the KEAP1-CUL3 interaction nor binding data to show the contributions of different domains to their binding affinity. We determined a crystal structure of the BTB and 3-box domains of human KEAP1 in complex with the CUL3 N-terminal domain that showed a heterotetrameric assembly with 2:2 stoichiometry. To support the structural data, we developed a versatile TR-FRET-based assay system to profile the binding of BTB-domain-containing proteins to CUL3 and determine the contribution of distinct protein features, revealing the importance of the CUL3 N-terminal extension for high affinity binding. We further provide direct evidence that the investigational drug CDDO does not disrupt the KEAP1-CUL3 interaction, even at high concentrations, but reduces the affinity of KEAP1-CUL3 binding. The TR-FRET-based assay system offers a generalizable platform for profiling this protein class and may form a suitable screening platform for ligands that disrupt these interactions by targeting the BTB or 3-box domains to block E3 ligase function.

Evaluation of Serum Albumin-Coated Bone Allograft for Bone Regeneration: A Seven-Year Follow-Up Study of 26 Cases

We have previously reported that serum albumin-coated bone allograft (BoneAlbumin, BA) is an effective bone substitute. It improves bone regeneration at the patellar and tibial donor sites six months after harvesting bone-patellar tendon-bone (BPTB) autografts for primary anterior cruciate ligament reconstruction (ACLR). In the present study, we examined these donor sites seven years after implantation. The study group (N = 10) received BA-enhanced autologous cancellous bone at the tibial and BA alone at the patellar site. The control group (N = 16) received autologous cancellous bone at the tibial and blood clot at the patellar site. We evaluated subcortical density, cortical thickness, and bone defect volume via CT scans. At the patellar site, subcortical density was significantly higher in the BA group at both time points. There was no significant difference in cortical thickness between the two groups at either donor site. The control group's bone defect significantly improved and reached the BA group's values at both sites by year seven. Meanwhile, the bone defects in the BA group did not change significantly and were comparable to the six-month measurements. No complications were observed. There are two limitations in this study: The number of patients recruited is small, and the randomization of the patients could have improved the quality of the study as the control group patients were older compared to the study group patients. Our 7-year results seem to demonstrate that BA is a safe and effective bone substitute that supports faster regeneration of donor sites and results in good-quality bone tissue at the time of ACLR with BPTB autografts. However, studies with a larger number of patients are required to definitively confirm the preliminary results of our study.

TNFα stimulates the proliferation of immature Sertoli cells by attenuating UPS-degradation of cyclin D1 and leads to the delay of BTB maturation in pubertal rats

BACKGROUNDS

The Sertoli cell that plays a vital role during spermatogenesis is a known target of physiological and pathological factors affecting testicular development. Tumor necrosis factor alpha (TNFα) participates in the blood-testis barrier reconstruction, cell apoptosis, and inflammatory response by recognizing receptors on Sertoli cell. TNFα has also been shown to induce the proliferation of immature Sertoli cell in vitro, yet the mechanism still remains unclarified.

OBJECTIVES

This study was designed to investigate the effect of TNFα on blood-testis barrier development during puberty and the underlying mechanisms of TNFα-induced immature Sertoli cell proliferation.

MATERIALS AND METHODS

Immature male Sprague-Dawley rats of postnatal day 12 were intraperitoneally injected with TNFα. Biotin-labeled method was used to detect permeability of the developing blood-testis barrier after TNFα treatment, and the distribution of occludin and junctional adhesion molecule-A (JAM-A) were detected by immunofluorescence. Sertoli cells isolated from Sprague-Dawley rats of postnatal day 10 were cultured in vitro and treated with TNFα. Cell proliferation rate was reflected by Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU) assay. Immunoblot and quantitative polymerase chain reaction were used to detect the expression of proliferating cell nuclear antigen, Fbxo4, and cyclin D1. Immunoprecipitation was used to detect the ubiquitination of cyclin D1 and the interaction between Fbxo4 and cyclin D1. Ammonium pyrrolidinedithiocarbamate (PDTC) was applied to detect the effect of nuclear factor kappaB (NFκB) activity inhibition on TNFα-induced Sertoli cell proliferation. The adenoviral recombinant plasmid containing rat Fbxo4 gene was constructed to investigate the effect of Fbxo4 overexpression on Sertoli cell proliferation promoted by TNFα.

RESULTS

The in vivo experiment revealed a significant delay of blood-testis barrier maturation in pubertal rats caused by exogenous TNFα. TNFα (10 ng/ml) treatment in vitro was found to promote the proliferation of immature Sertoli cells, accompanied with increased NFκB activity and cyclin D1 protein level. The level of Fbxo4 and ubiquitination of cyclin D1 were decreased after TNFα treatment. Inhibitor of NFκB or overexpression of Fbxo4 could both reverse the TNFα-induced proliferation of immature Sertoli cells, meanwhile restore the ubiquitin-proteasome system-dependent degradation of cyclin D1. Overexpression of Fbxo4 could not affect the activation of NFκB caused by TNFα.

CONCLUSION

These results indicate that TNFα inhibits the ubiquitination and degradation of cyclin D1 through the NFκB pathway, thereby promoting the proliferation of immature Sertoli cell in vitro and inducing the delay of blood-testis barrier maturation in pubertal rats.

Transcription factor ZNF22 regulates blood-tumor barrier permeability by interacting with HDAC3 protein

OBJECTIVE

The primary goals of this study were to investigate the potential roles of ZNF22 and HDAC3 as a histone deacetylase in regulating an increases in blood-tumor barrier (BTB) permeability and some of the possible molecular mechanisms associated with this effect.

METHODS

The expression of ZNF22 and HDAC3 in glioma-exposed endothelial cells (GECs) of BTB were detected transcription real-time PCR or western blot. The interaction of ZNF22 and HDAC3 in GECs associated with transcript effect was analyzed by means of Co-Immunoprecipitation and luciferase reporter assay.

RESULTS

In the present investigation, GECs expressed higher levels of ZNF22 as a zinc finger transcription factor and HDAC3 than endothelial cells. We then affirmed that silencing HDAC3 or ZNF22 led to a reduction in BTB permeability. By bioinformatics analysis, chromatin immunoprecipitation (ChIP) assays and luciferase assay, we found that ZNF22 had a target binding relationship with the promoter regions of ZO-1, Occludin, and Claudin-5 and negatively regulated the expression of ZO-1, Occludin, and Claudin-5. Furthermore, we revealed that HDAC3, as a co-transcript repressor with histone deacetylase activity, could interact with ZNF22 to hinder the expression of TJ-associated proteins, thereby further facilitating the permeability of BTB.

CONCLUSION

ZNF22 acted as a transcription factor in conjunction with HDAC3 to modulate the expression of TJ-associated proteins, which was correlated with an increase in BTB permeability. These results may provide new strategies and targets for the chemotherapy of gliomas as well as intracranial infections.

MARK2 and MARK4 Regulate Sertoli Cell BTB Dynamics Through Microtubule and Actin Cytoskeletons

Microtubule affinity-regulating kinases (MARKs) are nonreceptor Ser/Thr protein kinases known to regulate cell polarity and microtubule dynamics in Caenorhabditis elegans, Drosophila, invertebrates, vertebrates, and mammals. An earlier study has shown that MARK4 is present at the ectoplasmic specialization and blood-testis barrier (BTB) in the seminiferous epithelium of adult rat testes. Here, we report the function of MARK4 and another isoform MARK2 in Sertoli cells at the BTB. Knockdown of MARK2, MARK4, or MARK2 and MARK4 by RNAi using the corresponding siRNA duplexes without apparent off-target effects was shown to impair tight junction (TJ)-permeability barrier at the Sertoli cell BTB. It also disrupted microtubule (MT)- and actin-based cytoskeletal organization within Sertoli cells. Although MARK2 and MARK4 were shown to share sequence homology, they likely regulated the Sertoli cell BTB and MT cytoskeleton differently. Disruption of the TJ-permeability barrier following knockdown of MARK4 was considerably more severe than loss of MARK2, though both perturbed the barrier. Similarly, loss of MARK2 affected MT organization in a different manner than the loss of MARK4. Knockdown of MARK2 caused MT bundles to be arranged around the cell periphery, whereas knockdown of MARK4 caused MTs to retract from the cell edge. These differences in effects on the TJ-permeability barrier are likely from the unique roles of MARK2 and MARK4 in regulating the MT cytoskeleton of the Sertoli cell.

LPS-Induced Systemic Inflammation Caused mPOA-FSH/LH Disturbance and Impaired Testicular Function

Male reproductive function is key to the continuation of species and is under sophisticated regulation, challenged by various stressors including inflammation. In the lipopolysaccharide (LPS) intraperitoneal injection-induced acute systemic inflammation, male fecundity was compromised with decreased testosterone level, damaged spermatogenesis, and downregulations of testicular gene expression levels involved in steroidogenesis regulation and blood-testis barrier. It is also noteworthy that the testis is more sensitive to acute stress caused by LPS-induced systemic inflammation. LPS treatment resulted in lower testicular gene expression levels of steroidogenic acute regulatory protein, cholesterol side-chain cleavage enzyme, and cytochrome P450 family 11 subfamily B member 1 after LPS treatment, while no such decrease was found in the adrenal gland. In parallel to the significant decreases in testicular intercellular adhesion molecule 1, tight junction protein 1, and gap junction alpha-1 protein gene expression with LPS treatment, no decrease was found in the epididymis. In the brain, LPS treatment caused higher medial preoptic area (mPOA) activation in the hypothalamus, which is accompanied by elevated blood follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels, suggesting a disturbed hypothalamic-pituitary-gonad axis function. Besides mPOA, brain c-fos mapping and quantitative analysis demonstrated a broad activation of brain nuclei by LPS, including the anterior cingulate cortex, lateral septum, paraventricular nucleus of the hypothalamus, basolateral amygdala, ventral tegmental area, lateral habenular nucleus, locus coeruleus, Barrington's nucleus, and the nucleus of the solitary tract, accompanied by abnormal animal behavior. Our data showed that LPS-induced inflammation caused not only local testicular damage but also a systemic disturbance at the brain-testis axis level.

Polystyrene microplastics disrupt the blood-testis barrier integrity through ROS-Mediated imbalance of mTORC1 and mTORC2

It has been found that polystyrene microplastics (PS-MPs) exposure leads to decreased sperm quality and quantity, and we aim to explore the underlying mechanisms. Therefore, we gave 20 mg/kg body weight (bw) and 40 mg/kg bw 4 μm and 10 μm PS-MPs to male Balb/c mice by gavage. RNA sequencing of testes was performed. After PS-MPs exposure, blood-testis barrier (BTB) integrity was impaired. Since cytoskeleton was closely related to BTB integrity maintenance, and cytoskeleton disorganization could be induced by PS-MPs exposure in the testis, which resulted in the truncation of actin filaments and disruption of BTB integrity. Such processes were attributed to the differential expression of Arp3 and Eps8 (two of the most important actin-binding proteins). According to the transcriptome sequencing results, we examined the oxidative stress level in the testes and Sertoli cells. We found that PS-MPs exposure induced increased reactive oxygen species (ROS) level, which destroyed the balance between mTORC1 and mTORC2 (the mTORC1 activity was increased, while the mTORC2 activity was decreased). In conclusion, PS-MPs induced the imbalance of mTORC1 and mTORC2 via the ROS burst, and altered the expression profile of actin-binding proteins, resulting in F-actin disorganization and reduced expression of junctional proteins in the BTB. Eventually PS-MPs led to BTB integrity disruption and spermatogenesis dysfunction.

Wnt5a Regulates Junctional Function of Sertoli cells Through PCP-mediated Effects on mTORC1 and mTORC2

The blood-testis barrier (BTB) and apical ectoplasmic specialization (ES), which are synchronized through the crosstalk of Sertoli cells and Sertoli germ cells, are required for spermatogenesis and sperm release. Here, we show that Wnt5a, a noncanonical Wnt signaling pathway ligand, is predominately expressed in both the BTB and apical ES and has a specific expression pattern during the seminiferous epithelium cycle. We employed siRNA to knockdown Wnt5a expression in testis and Sertoli cells, and then identified elongated spermatids that lost their polarity and were embedded in the seminiferous epithelium. Moreover, phagosomes were found near the tubule lumen. These defects were due to BTB and apical ES disruption. We also verified that the expression level and/or location of BTB-associated proteins, actin binding proteins (ABPs), and F-actin was changed after Wnt5a knockdown in vivo and in vitro. Additionally, we demonstrated that Wnt5a regulated actin dynamics through Ror2-mediated mTORC1 and mTORC2. This study clarified the molecular mechanism of Wnt5a in Sertoli cell junctions through the planar cell polarity (PCP) signaling pathway. Our findings could provide an experimental basis for the clinical diagnosis and treatment of male infertility caused by Sertoli cell junction impairment.

Bisphenol S perturbs Sertoli cell junctions in male rats via alterations in cytoskeletal organization mediated by an imbalance between mTORC1 and mTORC2

Bisphenol S (BPS) is now used as an alternative of bisphenol A (BPA), but has been implicated in male reproductive dysfunction-including diminished sperm number and quality and altered hormonal concentrations. However, the mechanisms of action subserving these effects remains unclear. In the present study, BPS at doses of 50 mg/kg bw and 100 mg/kg bw caused defects in the integrity of the blood-testis barrier (BTB) and apical ectoplasmic specialization (ES), and we also delineated an underlying molecular mechanism of action. BPS induced F-actin and α-tubulin disorganization in seminiferous tubules, which in turn led to the truncation of actin filaments and microtubules. Additionally, BPS was found to perturb the expression of the actin-binding proteins Arp3 and Eps8, which are critical for the organization of the actin filaments. mTORC1 and mTORC2 manifest opposing roles in Sertoli cell junctional function, and we demonstrated that mTORC1/rpS6/Akt/MMP9 signaling was increased and that mTORC2/rictor activity was also attenuated. In summary, we showed that BPS-induced disruption of the BTB and apical ES perturbed normal spermatogenic function that was mediated by mTORC1 and mTORC2. The imbalance in mTORC1 and mTORC2, in turn, altered the expression of actin-binding proteins, resulting in the impairment of F-actin and MT organization, and inhibited the expression of junctional proteins at the BTB and apical ES.

Brain metastasis models: What should we aim to achieve better treatments?

Brain metastasis is emerging as a unique entity in oncology based on its particular biology and, consequently, the pharmacological approaches that should be considered. We discuss the current state of modelling this specific progression of cancer and how these experimental models have been used to test multiple pharmacologic strategies over the years. In spite of pre-clinical evidences demonstrating brain metastasis vulnerabilities, many clinical trials have excluded patients with brain metastasis. Fortunately, this trend is getting to an end given the increasing importance of secondary brain tumors in the clinic and a better knowledge of the underlying biology. We discuss emerging trends and unsolved issues that will shape how we will study experimental brain metastasis in the years to come.

Addressing BBB Heterogeneity: A New Paradigm for Drug Delivery to Brain Tumors

Effective treatments for brain tumors remain one of the most urgent and unmet needs in modern oncology. This is due not only to the presence of the neurovascular unit/blood-brain barrier (NVU/BBB) but also to the heterogeneity of barrier alteration in the case of brain tumors, which results in what is referred to as the blood-tumor barrier (BTB). Herein, we discuss this heterogeneity, how it contributes to the failure of novel pharmaceutical treatment strategies, and why a "whole brain" approach to the treatment of brain tumors might be beneficial. We discuss various methods by which these obstacles might be overcome and assess how these strategies are progressing in the clinic. We believe that by approaching brain tumor treatment from this perspective, a new paradigm for drug delivery to brain tumors might be established.

Control of craniofacial and brain development by Cullin3-RING ubiquitin ligases: Lessons from human disease genetics

Metazoan development relies on intricate cell differentiation, communication, and migration pathways, which ensure proper formation of specialized cell types, tissues, and organs. These pathways are crucially controlled by ubiquitylation, a reversible post-translational modification that regulates the stability, activity, localization, or interaction landscape of substrate proteins. Specificity of ubiquitylation is ensured by E3 ligases, which bind substrates and co-operate with E1 and E2 enzymes to mediate ubiquitin transfer. Cullin3-RING ligases (CRL3s) are a large class of multi-subunit E3s that have emerged as important regulators of cell differentiation and development. In particular, recent evidence from human disease genetics, animal models, and mechanistic studies have established their involvement in the control of craniofacial and brain development. Here, we summarize regulatory principles of CRL3 assembly, substrate recruitment, and ubiquitylation that allow this class of E3s to fulfill their manifold functions in development. We further review our current mechanistic understanding of how specific CRL3 complexes orchestrate neuroectodermal differentiation and highlight diseases associated with their dysregulation. Based on evidence from human disease genetics, we propose that other unknown CRL3 complexes must help coordinate craniofacial and brain development and discuss how combining emerging strategies from the field of disease gene discovery with biochemical and human pluripotent stem cell approaches will likely facilitate their identification.

An update on graft-tunnel mismatch in anterior cruciate ligament reconstruction: A survey of the experts in the field of orthopedic sports medicine demonstrates no clear consensus in management

BACKGROUND

The purpose of this study was to identify and report on the rate at which leaders in orthopaedic surgery are encountering GTM, their treatment methods and to identify whether these clinicians' demographics or techniques correlate with their GTM incidence and/or treatment algorithms.

METHODS

A survey was sent to identify the rate at which member orthopaedic surgeons of the American Orthopaedic Society for Sports Medicine (AOSSM), the National Football League Physicians Society (NFLPS), and the Herodicus Society are encountering GTM in ACL reconstruction with BTB graft and to establish what methods are most commonly utilized.

RESULTS

In total, 260 orthopaedic surgeons completed the survey. Respondents most frequently reported GTM in 1-5% of cases, with GTM most often between 5 and 10 mm. For lower levels of GTM, surgeons are most frequently recessing the femoral bone plug and adding a cortical suspensory device or outside-in fixation. Higher degrees of GTM are most commonly supplemented with a screw/post on the tibia. Those with >15 years of experience were more commonly using a transtibial femoral drilling with lower tibial tunnel angulation, and lower incidences of GTM than their less experienced counterparts.

CONCLUSION

There is tremendous variability in the incidence and management of GTM in ACL reconstruction with BTB graft with no clear consensus among experts. Differences are seen in ACL reconstruction techniques and means of correcting GTM when evaluating based on years of surgical experience and Sports Medicine Fellowship completion.

Structural analysis of the PATZ1 BTB domain homodimer

PATZ1 is a ubiquitously expressed transcriptional repressor belonging to the ZBTB family that is functionally expressed in T lymphocytes. PATZ1 targets the CD8 gene in lymphocyte development and interacts with the p53 protein to control genes that are important in proliferation and in the DNA-damage response. PATZ1 exerts its activity through an N-terminal BTB domain that mediates dimerization and co-repressor interactions and a C-terminal zinc-finger motif-containing domain that mediates DNA binding. Here, the crystal structures of the murine and zebrafish PATZ1 BTB domains are reported at 2.3 and 1.8 Å resolution, respectively. The structures revealed that the PATZ1 BTB domain forms a stable homodimer with a lateral surface groove, as in other ZBTB structures. Analysis of the lateral groove revealed a large acidic patch in this region, which contrasts with the previously resolved basic co-repressor binding interface of BCL6. A large 30-amino-acid glycine- and alanine-rich central loop, which is unique to mammalian PATZ1 amongst all ZBTB proteins, could not be resolved, probably owing to its flexibility. Molecular-dynamics simulations suggest a contribution of this loop to modulation of the mammalian BTB dimerization interface.

Testin regulates the blood-testis barrier via disturbing occludin/ZO-1 association and actin organization

The blood-testis barrier (BTB) separates the seminiferous epithelium into the apical and basal compartments. The BTB has to operate timely and accurately to ensure the correct migration of germ cells, meanwhile maintaining the immunological barrier. Testin was first characterized from primary Sertoli cells, it is a secretory protein and a sensitive biomarker to monitor junctions between Sertoli and germ cells. Till now, the functions of testin on BTB dynamics and the involving mechanisms are unknown. Herein, testin acts as a regulatory protein on BTB integrity. In vitro testin knockdown by RNAi caused significant damage to the Sertoli cell barrier with no apparent changes in the protein levels of several major tight junction (TJ), adhesion junction, and gap junction proteins. Also, testin RNAi caused the diffusion of two TJ structural proteins, occludin and ZO-1, diffusing away from the Sertoli cell surface into the cytoplasm. Association and colocalization between ZO-1 and occludin were decreased after testin RNAi, examined by Co-IP and coimmunofluorescent staining, respectively. Furthermore, testin RNAi induced a dramatic disruption on the arrangement of actin filament bundles and a reduced F-actin/G-actin ratio. The actin regulatory protein ARP3 appeared at the Sertoli cell interface after testin RNAi without its protein level change, whereas overexpressing testin in Sertoli cells showed no effect on TJ barrier integrity. The above findings suggest that besides as a monitor for Sertoli-germ cell junction integrity, testin is also an essential molecule to maintain Sertoli-Sertoli junctions.

CRL3s: The BTB-CUL3-RING E3 Ubiquitin Ligases

The ubiquitin proteasome pathway is one of the major regulatory tools used by eukaryotic cells. The evolutionarily conserved cullin family proteins can assemble as many as >600 distinct E3 ubiquitin ligase complexes that regulate diverse cellular pathways. In most of Cullin-RING ubiquitin ligase (CRL) complexes, separate linker and adaptor proteins build the substrate recognition module. Differently, a single BTB-containing adaptor molecule utilizing two protein interaction sites can link the CUL3 scaffold to the substrate, forming as many as 188 CUL3-BTB E3 ligase complexes in mammals. Here, we review the most recent studies on CRL3 complexes, with a focus on the model for CUL3 assembly with its BTB-containing substrate receptors. Also, we summarize the current knowledge of CRL3 substrates and their relevant biological functions. Next, we discuss the mutual exclusivity of somatic mutations in KEAP1, NRF2, and CUL3 in human lung cancer. Finally, we highlight new strategies to expand CUL3 substrates and discuss outstanding questions remaining in the field.

The extremely halotolerant black yeast Hortaea werneckii - a model for intraspecific hybridization in clonal fungi

The polymorphic black yeast Hortaea werneckii (Capnodiales, Ascomycota) is extremely halotolerant (growth from 0 to 30% [w/v] NaCl) and has been extensively studied as a model for halotolerance in Eukaryotes for over two decades. Its most frequent sources are hypersaline environments and adjacent sea-water habitats in temperate, subtropical and tropical climates. Although typically saprobic, H. werneckii can also act as a commensal coloniser on human skin, causing tinea nigra on hands and soles. Here, we report that addition of NaCl to culture media expands the growth range of H. werneckii to 37 °C, which explains its colonisation of human skin, with its increased salinity. The morphological and physiological plasticity/ versatility of H. werneckii indicate that a species complex might be involved. This was investigated in this polyphasic taxonomic analysis based on the global diversity of H. werneckii strains collected from hypersaline environments, and from humans and animals. Analysis of D1/D2domains of 28S and internal transcribed spacer rDNA revealed 10 and 17 genotypes, respectively, that were not always compliant. The genotypes have global distributions. Human and environmental strains with the same genotypes are intermingled. Due to the limited number of phylogenetically informative characters in the ribosomal DNA dataset, the partial genes encoding for β-tubulin (BTB) and mini-chromosome maintenance protein (MCM7) were also sequenced. The use of these genes was hampered by ambiguous sequences obtained by Sanger sequencing, as a consequence of the diploid and highly heterozygous genome of many H. werneckii strains. Analysis of the BTB and MCM7 genes showed that in some cases two copies of the gene from the same genome are positioned in distant phylogenetic clusters of the intraspecific gene tree. Analysis of whole-genome sequences of selected H. werneckii strains generally confirmed the phylogenetic distances estimated on the basis of ribosomal genes, but also showed substantial reticulation within the phylogenetic history of the strains. This is in line with the hypothesis that the diploid genomes of H. werneckii were formed by hybridizations, which have sometimes occurred between relatively divergent strains.

Structural Basis for Recruitment of DAPK1 to the KLHL20 E3 Ligase

BTB-Kelch proteins form the largest subfamily of Cullin-RING E3 ligases, yet their substrate complexes are mapped and structurally characterized only for KEAP1 and KLHL3. KLHL20 is a related CUL3-dependent ubiquitin ligase linked to autophagy, cancer, and Alzheimer's disease that promotes the ubiquitination and degradation of substrates including DAPK1, PML, and ULK1. We identified an “LPDLV”-containing motif in the DAPK1 death domain that determines its recruitment and degradation by KLHL20. A 1.1-Å crystal structure of a KLHL20 Kelch domain-DAPK1 peptide complex reveals DAPK1 binding as a loose helical turn that inserts deeply into the central pocket of the Kelch domain to contact all six blades of the β propeller. Here, KLHL20 forms salt-bridge and hydrophobic interactions including tryptophan and cysteine residues ideally positioned for covalent inhibitor development. The structure highlights the diverse binding modes of β-propeller domains versus linear grooves and suggests a new target for structure-based drug design.

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An “LPDLV” motif in DAPK1 determines its recruitment and degradation by KLHL20

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1.1-Å crystal structure determined of a KLHL20 Kelch domain-DAPK1 peptide complex

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A DAPK1 helical turn inserts into the β propeller to contact all six Kelch repeats

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KLHL20 shows a hydrophobic binding pocket suitable for inhibitor development

miR-132-3p boosts caveolae-mediated transcellular transport in glioma endothelial cells by targeting PTEN/PI3K/PKB/Src/Cav-1 signaling pathway

Blood-brain tumor barrier (BTB) impedes the transportation of antitumor therapeutic drugs into brain tumors. Its mechanism is still unknown, but learning how to improve the BTB permeability is critical for drug intervention. Recently, microRNAs (miRNAs) have appeared as regulation factors of numerous biologic processes and therapeutic targets of diverse diseases. In this study, we have identified that miR-132-3p is an essential miRNA by increasing the transcellular transport through the BTB. We found that miR-132-3p expression was significantly up-regulated in glioma endothelial cells (GECs). Furthermore we showed that miR132-3p⁺ greatly induced the endocytosis of cholera toxin subunit B and FITC-bovine serum albumin and up-regulated the expression of p-PKB, p-Src and Tyr14 phosphorylation of caveolin-1 (p-Cav-1), while phosphatase and tensin homolog deleted on chromosome 10 (PTEN) expression was markedly down-regulated in GECs. Our results identify PTEN as a direct and functional downstream target of miR-132-3p, which is involved in the regulation of p-PKB, p-Src, and p-Cav-1. The inhibitors for PI3K and Src significantly reversed the increase of p-Cav-1 induced by miR-132-3p. Moreover, overexpression of PTEN greatly reduced the endocytosis of cholera toxin subunit B and the up-regulation of p-Cav-1 induced by agomiR132-3p, suggesting that miR132-3p⁺ increases the endothelial permeability by inhibition of PTEN expression. In addition, miR132-3p⁺ significantly increased the delivery of doxorubicin across the BTB in vitro and contributed to the accumulation of doxorubicin within the brain tumor tissue. Our results show that miR-132-3p contributes to the increased permeability of BTB by targeting PTEN/PI3K/PKB/Src/Cav-1, thereby revealing a novel drug target for the treatment of brain gliomas.-Gu, Y., Cai, R., Zhang, C., Xue, Y., Pan, Y., Wang, J., Zhang, Z. miR-132-3p boosts caveolae-mediated transcellular transport in glioma endothelial cells by targeting PTEN/PI3K/PKB/Src/Cav-1 signaling pathway.

Vitamin E and vitamin C attenuate Di-(2-ethylhexyl) phthalate-induced blood-testis barrier disruption by p38 MAPK in immature SD rats

As an environmental endocrine disruptor, Di-(2-ethylhexyl) phthalate (DEHP) affects blood-testis barrier (BTB)-associated proteins expression, which compromises BTB integrity and causes infertility. Notably, DEHP-induced testicular toxicity is related to oxidative stress, but the specific mechanism remains unclear. Therefore, we sought to investigate this mechanism and determine whether vitamin C and vitamin E administration would attenuate the BTB impairment induced by DEHP in vivo and by Mono-(2-Ethylhexyl) Phthalate (MEHP) in vitro, respectively. HE staining and EM found that DEHP exposure led to spermatogenesis dysfunction and BTB disruption, respectively. The Western blot and immunofluorescence results showed that DEHP exposure caused BTB impairment through oxidative stress-mediated p38 mitogen-activated protein kinase (MAPK) signaling pathway. Furthermore, Vitamin E and vitamin C could alleviate the oxidative stress, block DEHP-induced spermatogenesis dysfunction and BTB disruption by inhibiting p38 MAPK signaling pathway. In summary, vitamin E and vitamin C are good candidates for the treatment of DEHP-induced male infertility.

DEHP exposure destroys blood-testis barrier (BTB) integrity of immature testes through excessive ROS-mediated autophagy

Di-(2-ethylhexyl) phthalate (DEHP), is known to impair testicular functions and reproduction. However, its effects on immature testis Blood-testis barrier (BTB) and the underlying mechanisms remain obscure. We constructed a rat model to investigate the roles of autophagy in BTB toxicity induced by DEHP. Sprague–Dawley rats were developmentally exposed to 0, 250 and 500 mg/kg DEHP via intragastric administration from postnatal day (PND) 1 to PND 35. Testicular morphology, expressions of BTB junction proteins and autophagy related proteins were detected. In addition, expressions of oxidative stress markers were also analyzed. Our results demonstrated that developmental DEHP exposure induced decreasing organ coefficients of immature testes and severe testicular damage in histomorphology. The expressions of junctional proteins were down-regulated significantly after DEHP treatment. Intriguingly, DEHP simultaneously increased the number of autophagosomes and the levels of autophagy marker LC3-II and p62, suggesting that the accumulated autophagosomes resulted from impaired autophagy degradation. Moreover, the expressions of HO-1 and SOD levels remarkably decreased after DEHP exposure. Vitamins E and C could alleviate the DEHP-induced oxidative stress, reverse the autophagy defect and restore the BTB impairment. Taken together, DEHP exposure destroys immature testis blood-testis barrier (BTB) integrity through excessive ROS-mediated autophagy.

MiR-142-3p Inhibits TGF-β3-Induced Blood-Testis Barrier Impairment by Targeting Lethal Giant Larvae Homolog 2

BACKGROUND/AIMS

Transforming growth factor-β3 (TGF-β3) has been proved to perturb the blood-testis barrier (BTB) by accelerating junction protein endocytosis in Sertoli cells (SCs) to accommodate the traversing of preleptotene spermatocytes across the BTB around stage VIII in rat. Yet the molecular network underlying the impairment of TGF-β3 on BTB integrity is not fully elucidated. Our study herein was designed to investigate the participation of microRNA-142-3p (miR-142-3p), which has been reported to affect TGF-β3 signaling via different pathways, during BTB dynamics and the corresponding mechanisms.

METHODS

MiRNA mimic or agomiRNA was co-administered with or without TGF-β3 in the cultured SCs or in the rat testis. The SC permeability barrier function was reflected by measuring the transepithelial resistance (TER) and the permeability of the sodium fluorescein (Na-F). The BTB integrity was detected by the permeation of biotin. A luciferase reporter assay was used to testify the potential target of miR-142-3p, lethal giant larvae 2 (Lgl2). Laser capture microdissection (LCM) was applied to acquire cell components of different stages of seminiferious tubules, followed by detection of the expression levels of miR-142-3p, TGF-β3, and Lgl2 by qPCR. The SC barrier function was also detected as above in the presence of TGF-β3 after Lgl2 knockdown.

RESULTS

We revealed a reversion of TGF-β3-induced BTB impairment after miR-142-3p treatment both in vitro and in vivo. Meanwhile, the activation of Cdc42 and reduction in occludin aroused by TGF-β3 were also reversed by miR-142-3p. The predicted binding of miR-142-3p with 3'-untranslated region (3'-UTR) of Lgl2, was verified by the luciferase assay. Moreover, an increased Lgl2 level in TGF-β3-treated SCs was found and correlated stage-specific expressions of TGF-β3, miR-142-3p, and Lgl2 were revealed. Knockdown of Lgl2 in SCs was shown to partially antagonize the BTB disruption mediated by TGF-β3.

CONCLUSIONS

Collectively, our results suggest a resistance of miR-142-3p on the BTB impairment caused by TGF-β3 during the seminiferous epithelial cycle by targeting Lgl2.

The Role of miR-330-3p/PKC-α Signaling Pathway in Low-Dose Endothelial-Monocyte Activating Polypeptide-II Increasing the Permeability of Blood-Tumor Barrier

This study was performed to determine whether EMAP II increases the permeability of the blood-tumor barrier (BTB) by affecting the expression of miR-330-3p as well as its possible mechanisms. We determined the over-expression of miR-330-3p in glioma microvascular endothelial cells (GECs) by Real-time PCR. Endothelial monocyte-activating polypeptide-II (EMAP-II) significantly decreased the expression of miR-330-3p in GECs. Pre-miR-330-3p markedly decreased the permeability of BTB and increased the expression of tight junction (TJ) related proteins ZO-1, occludin and claudin-5, however, anti-miR-330-3p had the opposite effects. Anti-miR-330-3p could enhance the effect of EMAP-II on increasing the permeability of BTB, however, pre-miR-330-3p partly reversed the effect of EMAP-II on that. Similarly, anti-miR-330-3p improved the effects of EMAP-II on increasing the expression levels of PKC-α and p-PKC-α in GECs and pre-miR-330-3p partly reversed the effects. MiR-330-3p could target bind to the 3′UTR of PKC-α. The results of in vivo experiments were similar to those of in vitro experiments. These suggested that EMAP-II could increase the permeability of BTB through inhibiting miR-330-3p which target negative regulation of PKC-α. Pre-miR-330-3p and PKC-α inhibitor decreased the BTB permeability and up-regulated the expression levels of ZO-1, occludin and claudin-5 while anti-miR-330-3p and PKC-α activator brought the reverse effects. Compared with EMAP-II, anti-miR-330-3p and PKC-α activator alone, the combination of the three combinations significantly increased the BTB permeability. EMAP-II combined with anti-miR-330-3p and PKCα activator could enhance the DOX’s effects on inhibiting the cell viabilities and increasing the apoptosis of U87 glioma cells. Our studies suggest that low-dose EMAP-II up-regulates the expression of PKC-α and increases the activity of PKC-α by inhibiting the expression of miR-330-3p, reduces the expression of ZO-1, occludin and claudin-5, and thereby increasing the permeability of BTB. The results can provide a new strategy for the comprehensive treatment of glioma.

Structural complexity in the KCTD family of Cullin3-dependent E3 ubiquitin ligases

Members of the potassium channel tetramerization domain (KCTD) family are soluble non-channel proteins that commonly function as Cullin3 (Cul3)-dependent E3 ligases. Solution studies of the N-terminal BTB domain have suggested that some KCTD family members may tetramerize similarly to the homologous tetramerization domain (T1) of the voltage-gated potassium (Kv) channels. However, available structures of KCTD1, KCTD5 and KCTD9 have demonstrated instead pentameric assemblies. To explore other phylogenetic clades within the KCTD family, we determined the crystal structures of the BTB domains of a further five human KCTD proteins revealing a rich variety of oligomerization architectures, including monomer (SHKBP1), a novel two-fold symmetric tetramer (KCTD10 and KCTD13), open pentamer (KCTD16) and closed pentamer (KCTD17). While these diverse geometries were confirmed by small-angle X-ray scattering (SAXS), only the pentameric forms were stable upon size-exclusion chromatography. With the exception of KCTD16, all proteins bound to Cul3 and were observed to reassemble in solution as 5 : 5 heterodecamers. SAXS data and structural modelling indicate that Cul3 may stabilize closed BTB pentamers by binding across their BTB-BTB interfaces. These extra interactions likely also allow KCTD proteins to bind Cul3 without the expected 3-box motif. Overall, these studies reveal the KCTD family BTB domain to be a highly versatile scaffold compatible with a range of oligomeric assemblies and geometries. This observed interface plasticity may support functional changes in regulation of this unusual E3 ligase family.

The T-SPOT.TB Test for Diagnosis of Breast Tuberculosis

OBJECTIVE

To assess the diagnostic value of the T-SPOT.TB test in cases of breast turberculosis (BTB) in China.

METHODS

We enrolled 13 female patients with primary BTB as the BTB test group and 10 healthy volunteers as the control group. The 2 groups underwent T-SPOT.TB tests and tuberculin skin tests (TSTs) before receiving a core-needle biopsy or excision biopsy. We then collected and analyzed T-SPOT.TB and TST data.

RESULTS

The sensitivity of the T-SPOT.TB test for detection of BTB (84.6%) was significantly greater than that of TST (53.8%) (P <.05); the specificity of each test (80.0% and 60.0%, respectively) for BTB was not significantly different (P >.05).

CONCLUSION

The T-SPOT.TB test could be a useful adjunct to current tests for diagnosis of BTB and could be used for early diagnosis of this condition.

Bone-Albumin filling decreases donor site morbidity and enhances bone formation after anterior cruciate ligament reconstruction with bone-patellar tendon-bone autografts

PURPOSE

Donor site pain affects 32-43 % of patients after anterior cruciate ligament surgery when the autograft is freshly harvested bone-patellar tendon-bone tissue. Our aim was to compare functional and morphological differences between donor sites with and without serum albumin-coated bone allograft filling.

METHODS

After harvesting and implanting the graft, the tibia site was filled with either fresh autologous cancellous bone enhanced with albumin-coated allograft or autologous bone alone. The patella site was filled either with albumin-coated allograft or with blood clot. Knee function was evaluated by the VISA, Lysholm and IKDC scores and a visual analog scale of pain during standing, kneeling and crouching after six weeks and six months. Computed tomography was performed at six months for morphological evaluation.

RESULTS

At six weeks, both groups were still recovering from surgery and the overall knee function was still impaired but the functional scores were significantly higher in the Bone-Albumin group. The pain with crouching and kneeling was also lower as compared to controls. At six months, the knee function scores were close to normal, with a slight decrease in the controls. Pain at kneeling was still prominent in the controls, but significantly lower in the Bone-Albumin group. Computed tomography showed significantly smaller bone defects and higher bone density in the Bone-Albumin group.

CONCLUSIONS

Results from the present study indicate that donor site pain, a disturbing long-term side effect of bone-patellar tendon-bone surgery, is significantly reduced if bone buildup in the patella and the tibia is augmented by serum albumin-coated bone allografts.

MiRNA-200b Regulates RMP7-Induced Increases in Blood-Tumor Barrier Permeability by Targeting RhoA and ROCKII

The primary goals of this study were to investigate the potential roles of miR-200b in regulating RMP7-induced increases in blood-tumor barrier (BTB) permeability and some of the possible molecular mechanisms associated with this effect. Microarray analysis revealed 34 significantly deregulated miRNAs including miR-200b in the BTB as induced by RMP7 and 8 significantly up-regulated miRNAs in the BTB by RMP7. RMP7 induced tight junction (TJ) opening of the BTB, thereby increasing BTB permeability. Associated with this effect of RMP7 was a decrease in miR-200b expression within the human cerebral microvascular endothelial cells line hCMEC/D3 (ECs) of the BTB. Overexpression of miR-200b inhibited endothelial leakage and restored normal transendothelial electric resistance values. A simultaneous shift in occludin and claudin-5 distributions from insoluble to soluble fractions were observed to be significantly reduced. In addition, overexpression of miR-200b inhibited the relocation of occludin and claudin-5 from cellular borders into the cytoplasm as well as the production of stress fiber formation in GECs (ECs with U87 glioma cells co-culturing) of the BTB. MiR-200b silencing produced opposite results as that obtained from that of the miR-200b overexpression group. Overexpression of miR-200b was also associated with a down-regulation in RhoA and ROCKII expression, concomitant with a decrease in BTB permeability. Again, results which were opposite to that obtained with the miR-200b silencing group. We further found that miR-200b regulated BTB permeability by directly targeting RhoA and ROCKII. Collectively, these results suggest that miR-200b's contribution to the RMP7-induced increase in BTB permeability was associated with stress fiber formation and TJ disassembly as achieved by directly targeting RhoA and ROCKII.

Structural basis of Keap1 interactions with Nrf2

Keap1 is a highly redox-sensitive member of the BTB-Kelch family that assembles with the Cul3 protein to form a Cullin-RING E3 ligase complex for the degradation of Nrf2. Oxidative stress disables Keap1, allowing Nrf2 protein levels to accumulate for the transactivation of critical stress response genes. Consequently, the Keap1-Nrf2 system is extensively pursued for the development of protein-protein interaction inhibitors that will stabilize Nrf2 for therapeutic effect in conditions of neurodegeneration, inflammation, and cancer. Here we review current progress toward the structure determination of Keap1 and its protein complexes with Cul3, Nrf2 substrate, and small-molecule antagonists. Together the available structures establish a rational three-dimensional model to explain the two-site binding of Nrf2 as well as its efficient ubiquitination.

Selective breeding: the future of TB management in African buffalo?

The high prevalence of bovine tuberculosis (BTB) in African buffalo (Syncerus caffer) in regions of southern African has a negative economic impact on the trade of animals and animal products, represents an ecological threat to biodiversity, and poses a health risk to local communities through the wildlife-cattle-human interface. Test and cull methods may not be logistically feasible in many free-range wildlife systems, and with the presence of co-existing BTB hosts and the limited effectiveness of the BCG vaccine in buffalo, there is a need for alternative methods of BTB management. Selective breeding for increased resistance to BTB in buffalo may be a viable method of BTB management in the future, particularly if genetic information can be incorporated into these schemes. To explore this possibility, we discuss the different strategies that can be employed in selective breeding programmes, and consider the implementation of genetic improvement schemes. We reflect on the suitability of applying this strategy for enhanced BTB resistance in African buffalo, and address the challenges of this approach that must be taken into account. Conclusions and the implications for management are presented.

Kelch proteins: emerging roles in skeletal muscle development and diseases

Our understanding of genes that cause skeletal muscle disease has increased tremendously over the past three decades. Advances in approaches to genetics and genomics have aided in the identification of new pathogenic mechanisms in rare genetic disorders and have opened up new avenues for therapeutic interventions by identification of new molecular pathways in muscle disease. Recent studies have identified mutations of several Kelch proteins in skeletal muscle disorders. The Kelch superfamily is one of the largest evolutionary conserved gene families. The 66 known family members all possess a Kelch-repeat containing domain and are implicated in diverse biological functions. In skeletal muscle development, several Kelch family members regulate the processes of proliferation and/or differentiation resulting in normal functioning of mature muscles. Importantly, many Kelch proteins function as substrate-specific adaptors for Cullin E3 ubiquitin ligase (Cul3), a core component of the ubiquitin-proteasome system to regulate the protein turnover. This review discusses the emerging roles of Kelch proteins in skeletal muscle function and disease.

Retinoic acid promotes Sertoli cell differentiation and antagonises activin-induced proliferation

From puberty and throughout adult spermatogenesis, retinoid signalling is essential for germ cell differentiation and male fertility. The initiation of spermatogonial differentiation and germ cell meiosis occurs under the direction of local retinoid signalling in the testis, and corresponds with the final phase of somatic Sertoli cell differentiation at puberty. Here, we consider the cellular and molecular basis of retinoid actions upon Sertoli cell differentiation. Primary rat Sertoli cells were isolated during the pubertal proliferative and quiescent phases at postnatal days 10- and 20- respectively, and cultured with all-trans-retinoic acid. We show that retinoid signalling can potently suppress activin-induced proliferation by antagonising G1 phase progression and entry into the cell cycle. Retinoid signalling was also found to initiate tight junction formation in primary Sertoli cells, consistent with a pro-differentiative role. This study implicates retinoid signalling in the differentiation of both somatic and germ cells in the testis at puberty.

T7 peptide-functionalized nanoparticles utilizing RNA interference for glioma dual targeting

Among all the malignant brain tumors, glioma is the deadliest and most common form with poor prognosis. Gene therapy is regarded as a promising way to halt the progress of the disease or even cure the tumor and RNA interference (RNAi) stands out. However, the existence of the blood-brain barrier (BBB) and blood tumor barrier (BTB) limits the delivery of these therapeutic genes. In this work, the delivery system targeting to the transferrin (Tf) receptor highly expressed on both BBB and glioma was successfully synthesized and would not compete with endogenous Tf. U87 cells stably express luciferase were employed here to simulate tumor and the RNAi experiments in vitro and in vivo validated that the gene silencing activity was 2.17-fold higher with the targeting ligand modification. The dual-targeting gene delivery system exhibits a series of advantages, such as high efficiency, low toxicity, stability and high transaction efficiency, which may provide new opportunities in RNAi therapeutics and nanomedicine of brain tumors.

Effects of electromagnetic radiation on morphology and TGF-β3 expression in mouse testicular tissue

Exposure to electromagnetic pulses in certain doses may lead to increase in the permeability of the blood testes barrier (BTB) in mice, which in turn affects spermatogenesis, penetration and spermiation. TGF-β3 is a key molecule involved in BTB permeability via regulation of tight junction proteins, and it participates in regulating spermatogenesis, synthesis of steroids and production of the extracellular matrix in testicular tissue. Therefore, it is hypothesized that TGF-β3 plays important roles in electromagnetic pulse (EMP)-induced changes in BTB permeability. In the present study, we carried out whole-body irradiation on mice using EMP of different intensities. No obvious pathological changes or significant increase in apoptosis was detected in testicular tissues after exposure to 100 and 200 pulses of intensity 200kV/m; however, with 400 pulses we observed the degeneration and shrinkage of testicular tissues along with a significant increase in apoptotic rate. Moreover, in the 100- and 200-EMP groups, a non-significant increase in TGF-β3 mRNA and protein expression was observed, whereas in the 400-EMP group a significant increase was observed (P<0.05). These results indicate that increase in the apoptotic rate of testicular tissues and increase in TGF-β3 expression may be one of the mechanisms for EMP-induced increase in BTB permeability in mice.

Neonatal exposure to zearalenone induces long term modulation of ABC transporter expression in testis

Mycotoxin zearalenone (ZEN) is a cereal contaminant produced by various species of Fusarium fungi. When interacting with estrogen receptors, ZEN leads to animal fertility disturbances and other reproductive pathologies. Few data are available on the effects of perinatal exposure to ZEN, particularly in the blood-testis barrier. The aim of this study was to assess the impact of ZEN in adult rats exposed neonatally. We focused on the expression and cellular localization of major ABC transporters expressed in adult rat testis, comparing ZEN effects with those of Estradiol Benzoate (EB) neonatal exposure. Dose-dependent and long term modulations of mRNA and protein levels of Abcb1, Abcc1, Abcg2, Abcc4 and Abcc5 were observed, along with Abcc4 protein cellular delocalization. ZEN exposure of SerW3 Sertoli cells showed modulation of Abcb1, Abcc4 and Abcc5. Comparison with EB exposure showed similar modulation profiles for Abcg2 but differential modulations for Abcb1, Abcc1, Abcc4 and Abcc5 in vivo, and a similar profile for Abcb1 modulation by ZEN and EB, but differential modulation for Abcc4 and Abcc5 in vitro. ZEN and EB effects were inhibited by in vitro addition of the pure anti-estrogen ICI 182.780, suggesting the at least partial implication of ZEN estrogenic activity in these modulations. These results suggested that ZEN neonatal exposure could affect the exposure of testis to ABC transporter substrates, and negatively influence spermatogenesis and male fertility.

The CUL3-KLHL18 ligase regulates mitotic entry and ubiquitylates Aurora-A

The cullin-RING family of ubiquitin ligases regulates diverse cellular functions, such as cell cycle control, via ubiquitylation of specific substrates. CUL3 targets its substrates through BTB proteins. Here we show that depletion of CUL3 and the BTB protein KLHL18 causes a delay in mitotic entry. Centrosomal activation of Aurora-A, a kinase whose activity is required for entry into mitosis, is also delayed in depleted cells. Moreover, we identify Aurora-A as a KLHL18-interacting partner. Overexpression of KLHL18 and CUL3 promotes Aurora-A ubiquitylation in vivo, and the CUL3-KLHL18-ROC1 ligase ubiquitylates Aurora-A in vitro. Our study reveals that the CUL3-KLHL18 ligase is required for timely entry into mitosis, as well as for the activation of Aurora-A at centrosomes. We propose that the CUL3-KLHL18 ligase regulates mitotic entry through an Aurora-A-dependent pathway.

Remote homologue identification of Drosophila GAGA factor in mouse

GAGA factor (GAF) is involved in both gene activation and gene repression and plays a role in the modulation of chromatin structure. In Drosophila, Trithroax like (Trl) gene encodes the DNA binding protein called GAGA factor (GAF). Trl-GAF binds to GAGA sites through its C2H2 zinc finger domain and has an N-terminal BTB/POZ domain. Identification of Trl-GAF homologue in mouse helps in deeper understanding of the mechanism and function. Conventional alignment tools such as BLAST and FASTA cannot identify homologues in mouse genome as their sequence identity is below 30%. In the present study, various sequence and structure analyses were followed for the detection of remote homologues of Drosophila GAGA FACTOR in mouse to identify as Zbtb3. Through homology modeling and docking approach, the zinc finger region of mouse Zbtb3 showed conserved residues and favorable DNA binding sites with GAGA sites similar to that of Drosophila GAGA FACTOR.