Unraveling the molecular targets pertinent to junction restructuring events during spermatogenesis using the Adjudin-induced germ cell depletion model

Transcriptomic investigation of the effects of TDCPP on PC12 and GC2 cells with experimental validation

TDCPP is a flame retardant which has nervous and reproductive toxicity. Although there is a close association between nervous and reproductive system, the exact toxic mechanism of TDCPP in these systems is still seldom, especially in a genome scale. In this study, we explored the transcriptomic landscape of TDCPP in PC12 and GC2 cells using RNAseq method. A total of 465 co-differential expressed genes were found. These genes were mainly enriched in extra-cellular matrix, cell adhesion, cell cycle arrest, oxidoreductase activity GO terms, and PI3K/AKT, focal adhesion, ECM-receptor interaction KEGG pathways. Hub genes (ANXA1, COL27A1, GAS6, GNB4 and THBS1) were extracted using STRING and confirmed by qPCR experiment. Vimentin, HSPA5 and Caspase3 were proved to be responsible to TDCPP in GC2 and PC12 cells. Knockdown assay in PC12 cells showed that these hub genes could also affect the protein expression of vimentin, HSPA5 and Caspase3. In summary, TDCPP might exert its toxic effect through disturbing focal adhesion, ECM-receptor interaction and PI3K/Akt pathways. One of the mechanisms could be influence on the cytoskeleton (vimentin), ER stress (HSPA5) and apoptosis (Caspase3). The sequence data in this study might be a useful resource for future TDCPP related researches.

Using publicly available transcriptomic data to identify mechanistic and diagnostic biomarkers in azoospermia and overall male infertility

Azoospermia, which is the absence of spermatozoa in an ejaculate occurring due to defects in sperm production, or the obstruction of the reproductive tract, affects about 1% of all men and is prevalent in up to 10–15% of infertile males. Conventional semen analysis remains the gold standard for diagnosing and treating male infertility; however, advances in molecular biology and bioinformatics now highlight the insufficiency thereof. Hence, the need to widen the scope of investigating the aetiology of male infertility stands pertinent. The current study aimed to identify common differentially expressed genes (DEGs) that might serve as potential biomarkers for non-obstructive azoospermia (NOA) and overall male infertility. DEGs across different datasets of transcriptomic profiling of testis from human patients with different causes of infertility/ impaired spermatogenesis and/or azoospermia were explored using the gene expression omnibus (GEO) database. Following the search using the GEOquery, 30 datasets were available, with 5 meeting the inclusion criteria. The DEGs for datasets were identified using limma R packages through the GEO2R tool. The annotated genes of the probes in each dataset were intersected with DEGs from all other datasets. Enriched Ontology Clustering for the identified genes was performed using Metascape to explore the possible connection or interaction between the genes. Twenty-five DEGs were shared between most of the datasets, which might indicate their role in the pathogenesis of male infertility. Of the 25 DEGs, eight genes (THEG, SPATA20, ROPN1L, GSTF1, TSSK1B, CABS1, ADAD1, RIMBP3) are either involved in the overall spermatogenic processes or at specific phases of spermatogenesis. We hypothesize that alteration in the expression of these genes leads to impaired spermatogenesis and, ultimately, male infertility. Thus, these genes can be used as potential biomarkers for the early detection of NOA.

Spermiation: Insights from Studies on the Adjudin Model

Spermatogenesis is comprised of a series of cellular events that lead to the generation of haploid sperm. These events include self-renewal of spermatogonial stem cells (SSC), proliferation of spermatogonia by mitosis, differentiation of spermatogonia and spermatocytes, generation of haploid spermatids via meiosis I/II, and spermiogenesis. Spermiogenesis consists of a series of morphological events in which spermatids are being transported across the apical compartment of the seminiferous epithelium while maturing into spermatozoa, which include condensation of the genetic materials, biogenesis of acrosome, packaging of the mitocondria into the mid-piece, and elongation of the sperm tail. However, the biology of spermiation remains poorly understood. In this review, we provide in-depth analysis based on the use of bioinformatics tools and an animal model that mimics spermiation through treatment of adult rats with adjudin, a non-hormonal male contraceptive known to induce extensive germ cell exfoliation across the seminiferous epithelium, but nost notably elongating/elongated spermatids. These analyses have shed insightful information regaridng the biology of spermiation.

mTORC1/rpS6 and p-FAK-Y407 signaling regulate spermatogenesis: Insights from studies of the adjudin pharmaceutical/toxicant model

In rodents and humans, the major cellular events at spermatogenesis include self-renewal of spermatogonial stem cells and undifferentiated spermatogonia via mitosis, commitment of spermatogonia to differentiation and transformation to spermatocytes, meiosis, spermiogenesis, and the release of spermatozoa at spermiation. While details of the morphological changes during these cellular events have been delineated, knowledge gap exists between the morphological changes in the seminiferous epithelium and the underlying molecular mechanism(s) that regulate these cellular events. Even though many of the regulatory proteins and biomolecules that modulate spermatogenesis are known based on studies using genetic models, the underlying regulatory mechanism(s), in particular signaling pathways/proteins, remain unexplored since much of the information regarding the signaling regulation is unknown. Studies in the past decade, however, have unequivocally demonstrated that the testis is using several signaling proteins and/or pathways to regulate multiple cellular events to modulate spermatogenesis. These include mTORC1/rpS6/Akt1/2 and p-FAK-Y407. While selective inhibitors and/or agonists and antagonists are available to examine some of these signaling proteins, their use have limitations due to their specificities and also potential systemic cytotoxicity. On the other hand, the use of genetic models has had profound implications for our understanding of the molecular regulation of spermatogenesis, and these knockout (null) models have also revealed the factors that are critical for spermatogenesis. Nonetheless, additional studies using in vitro and in vivo models are necessary to unravel the signaling pathways involved in regulating seminiferous epithelial cycle. Emerging data from studies, such as the use of the adjudin pharmaceutical/toxicant model, have illustrated that this non-hormonal male contraceptive drug is utilizing specific signaling pathways/proteins to induce specific defects in spermatogenesis, yielding mechanistic insights on the regulation of spermatogenesis. We sought to review these recent data in this article, highlighting an interesting approach that can be considered for future studies.

Cell polarity, cell adhesion, and spermatogenesis: role of cytoskeletons

In the rat testis, studies have shown that cell polarity, in particular spermatid polarity, to support spermatogenesis is conferred by the coordinated efforts of the Par-, Crumbs-, and Scribble-based polarity complexes in the seminiferous epithelium. Furthermore, planar cell polarity (PCP) is conferred by PCP proteins such as Van Gogh-like 2 (Vangl2) in the testis. On the other hand, cell junctions at the Sertoli cell–spermatid (steps 8–19) interface are exclusively supported by adhesion protein complexes (for example, α6β1-integrin-laminin-α3,β3,γ3 and nectin-3-afadin) at the actin-rich apical ectoplasmic specialization (ES) since the apical ES is the only anchoring device in step 8–19 spermatids. For cell junctions at the Sertoli cell–cell interface, they are supported by adhesion complexes at the actin-based basal ES (for example, N-cadherin-β-catenin and nectin-2-afadin), tight junction (occludin-ZO-1 and claudin 11-ZO-1), and gap junction (connexin 43-plakophilin-2) and also intermediate filament-based desmosome (for example, desmoglein-2-desmocollin-2). In short, the testis-specific actin-rich anchoring device known as ES is crucial to support spermatid and Sertoli cell adhesion. Accumulating evidence has shown that the Par-, Crumbs-, and Scribble-based polarity complexes and the PCP Vangl2 are working in concert with actin- or microtubule-based cytoskeletons (or both) and these polarity (or PCP) protein complexes exert their effects through changes in the organization of the cytoskeletal elements across the seminiferous epithelium of adult rat testes. As such, there is an intimate relationship between cell polarity, cell adhesion, and cytoskeletal function in the testis. Herein, we critically evaluate these recent findings based on studies on different animal models. We also suggest some crucial future studies to be performed.

Adjudin--A Male Contraceptive with Other Biological Activities

BACKGROUND

Adjudin has been explored as a male contraceptive for the last 15 years since its initial synthesis in the late 1990s. More than 50 papers have been published and listed in PubMed in which its mechanism that induces exfoliation of germ cells from the seminiferous epithelium, such as its effects on actin microfilaments at the apical ES (ectoplasmic specialization, a testis-specific actin-rich anchoring junction) has been delineated.

OBJECTIVE

Recent studies have demonstrated that, besides its activity to induce germ cell exfoliation from the seminiferous epithelium to cause reversible infertility in male rodents, adjudin possesses other biological activities, which include anti-cancer, anti-inflammation in the brain, and anti-ototoxicity induced by gentamicin in rodents. Results of these findings likely spark the interest of investigators to explore other medical use of this and other indazole-based compounds, possibly mediated by the signaling pathway(s) in the mitochondria of mammalian cells following treatment with adjudin. In this review, we carefully evaluate these recent findings.

METHODS

Papers published and listed at www.pubmed.org and patents pertinent to adjudin and its related compounds were searched. Findings were reviewed and critically evaluated, and summarized herein.

RESULTS

Adjudin is a novel compound that possesses anti-spermatogenetic activity. Furthermore, it possesses anti-cancer, anti-inflammation, anti-neurodegeneration, and anti-ototoxicity activities based on studies using different in vitro and in vivo models.

CONCLUSION

Studies on adjudin should be expanded to better understand its biological activities so that it can become a useful drug for treatment of other ailments besides serving as a male contraceptive.

A sirtuin activator and an anti-inflammatory molecule-multifaceted roles of adjudin and its potential applications for aging-related diseases

Adjudin was originally developed as an improved analog of lonidamine to serve as a non-hormonal reversible male contraceptive that could cause exfoliation of the immature sperms from the seminiferous epithelium. Recently, the functionality spectrum of adjudin expands beyond as an anti-spermatogenic agent, namely, it could function as an anti-cancer drug potentially useful for combination chemotherapy, and as an anti-inflammatory molecule that could protect against ischemic stroke injury. Most strikingly, adjudin acts through activation of mitochondrion-located Sirt3 to safeguard hair cells of the cochlea from ototoxicant such as gentamycin. Recent studies also indicate that adjudin could attenuate oxidative stress and cellular senescence. These findings suggest wider applications of this small molecule, particularly in aging-related diseases.

Testin and actin are key molecular targets of adjudin, an anti-spermatogenic agent, in the testis

Earlier studies have shown adjudin to cause aspermatogenesis by depleting virtually all germ cells from the seminiferous epithelium, leading to transient infertility; spermatogenesis and fertility were re-established several weeks later after germ cell proliferation and differentiation were reinitiated by spermatogonia. While adjudin is known to exert its initial effects at the apical ectoplasmic specialization (a testis-specific atypical anchoring junction), thereby perturbing spermatid adhesion, its molecular target(s) at this site is not known. Herein, we report the production of a specific antibody against adjudin after this compound was conjugated to an adjuvant (i.e., keyhole limpet hemocyanin) to maximize immune response in rabbits. This antibody was utilized for co-immunoprecipitation by using an affinity resin to pull-down the binding partners of adjudin. Using this approach coupled with mass spectrometry and immunoblotting, we show testin (a protein largely restricted to the apical ES in the adult testis) and actin-myosin to be molecular targets of adjudin. These findings provide a platform for future functional studies, not only to better understand the molecular mechanism behind adjudin-induced germ cell loss from the seminiferous epithelium, but also to understand the molecular basis of spermiation.

Adjudin protects against cerebral ischemia reperfusion injury by inhibition of neuroinflammation and blood-brain barrier disruption

Neuroinflammation mediated by activation of microglia and interruption of the blood-brain barrier (BBB) is an important factor that contributes to neuron death and infarct area diffusion in ischemia reperfusion injury. Finding novel molecules to regulate neuroinflammation is of significant clinical value. We have previously shown that adjudin, a small molecule compound known to possess antispermatogenic function, attenuates microglia activation by suppression of the NF-κB pathway. In this study we continued to explore whether adjudin could be neuroprotective by using the transient middle cerebral artery occlusion (tMCAO) model. Adjudin treatment after reperfusion significantly decreased the infarction volume and neuroscore compared to the vehicle group. Staining of CD11b showed that adjudin markedly inhibited microglial activation in both the cortex and the striatum, accompanied by a reduction in the expression and release of cytokines TNF-α, IL-1β and IL-6. Concomitantly, adjudin noticeably prevented BBB disruption after ischemia and reperfusion, as indicated by the reduction of IgG detection in the brain cortex and striatum versus the vehicle group. This finding was also corroborated by immunofluorescence staining and immunoblotting of tight junction-related proteins ZO-1, JAM-A and Occludin, where the reduction of these proteins could be attenuated by adjudin treatment. Moreover, adjudin obviously inhibited the elevated MMP-9 activity after stroke. Together these data demonstrate that adjudin protects against cerebral ischemia reperfusion injury, and we present an effective neuroinflammation modulator with clinical potential.

The Scribble/Lgl/Dlg polarity protein complex is a regulator of blood-testis barrier dynamics and spermatid polarity during spermatogenesis

During spermatogenesis, spermiogenesis that releases sperm into the tubule lumen and restructuring of the blood-testis barrier (BTB) that accommodates the transit of preleptotene spermatocytes take place simultaneously, but at the opposite ends of the seminiferous epithelium. These events are tightly regulated and coordinated; however, neither the underlying mechanism(s) nor the involving molecules are known. Herein, the Scribble/Lgl (Lethal giant larvae)/Dlg (Discs large) polarity complex was shown to regulate spermatid polarity during spermiogenesis and tight junction (TJ)-permeability barrier via changes in protein distribution at the apical ectoplasmic specialization and the BTB during the epithelial cycle, respectively. Scribble, Lgl2, and Dlg1 were found to be expressed by Sertoli and germ cells. Scribble also displayed stage-specific expression at the BTB, being highest at stages VII-VIII, colocalizing with TJ proteins occludin and ZO-1. Unlike components of other polarity complex modules, such as partitioning-defective 6, the knockdown of which by RNA interference was found to impede Sertoli cell TJ barrier, a knockdown of the Scribble complex (i.e. simultaneous knockdown of Scribble, Lgl and Dlg or Lgl alone; but not Scribble or Dlg alone) both in vitro and in vivo promoted the TJ integrity. This was mediated by reorganizing actin filament network at the Sertoli cell-cell interface, which, in turn, affected changes in the localization and/or distribution of occludin and/or β-catenin at the BTB. These knockdowns also perturbed F-actin organization at the Sertoli cell-spermatid interface, thereby modulating spermatid adhesion and polarity at the apical ectoplasmic specialization. In summary, the Scribble/Lgl/Dlg complex participates in the regulation of BTB dynamics and spermatid adhesion/polarity in the testis.

NAD+ treatment induces delayed autophagy in Neuro2a cells partially by increasing oxidative stress

NAD(+) plays important roles in various biological processes. In this study, we reported that treatment of NAD(+) induces delayed autophagy in Neuro2a cells. Moreover, the effects of NAD(+) on the autophagy in the cells appear to be, at least partially, mediated by oxidative stress. However, nicotinamide, a degradation product of NAD(+), does not affect the autophagy. Our experiments have further indicated that the NAD(+)-induced autophagy contributes to the NAD(+)-induced decrease in the survival of these cells. In summary, our study has provided the first evidence that NAD(+) treatment induces autophagy in cancer cells such as Neuro2a cells, which contributes to the NAD(+)-induced decrease in cancer cell survival.

Drug transporters and blood--testis barrier function

The blood--testis barrier (BTB) creates an immunological barrier that segregates the seminiferous epithelium into the basal and apical compartment. Thus, meiosis I/II and post-meiotic germ cell development take place in a specialized microenvironment in the apical compartment behind the BTB and these events are being shielded from the host immune system. If unwanted drugs and/or chemicals enter the apical compartment from the microvessels in the interstitium via the basal compartment, efflux pumps (e.g. P-glycoprotein) located in Sertoli cells and/or spermatids can actively transport these molecules out of the apical compartment. However, the mechanism(s) by which influx pumps regulate the entry of drugs/chemicals into the apical compartment is not known. In this study, a solute carrier (SLC) transporter organic anion transporting polypeptide 3 (Oatp3, Slco1a5) was shown to be an integrated component of the N-cadherin-based adhesion complex at the BTB. However, a knockdown of Oatp3 alone or in combination with three other major Sertoli cell drug influx pumps, namely Slc22a5, Slco6b1, and Slco6c1, by RNAi using corresponding specific siRNA duplexes failed to perturb the Sertoli cell tight junction (TJ) permeability barrier function. Yet, the transport of [(3)H]adjudin, a potential male contraceptive that is considered a toxicant to spermatogenesis, across the BTB was impeded following the knockdown of either Oatp3 or all the four SLC transporters. In short, even though drug transporters (e.g. influx pumps) are integrated components of the adhesion protein complexes at the BTB, they are not involved in regulating the Sertoli cell TJ permeability barrier function, instead they are only involved in the transport of drugs, such as adjudin, across the immunological barrier at the BTB.

VGF: an inducible gene product, precursor of a diverse array of neuro-endocrine peptides and tissue-specific disease biomarkers

The vgf gene (non-acronymic) is induced in vivo by neurotrophins including Nerve Growth Factor (NGF), Brain Derived Growth Factor (BDNF) and Glial Derived Growth Factor (GDNF), by synaptic activity and by homeostatic and other stimuli. Post-translational processing of a single VGF precursor gives raise to a varied multiplicity of neuro-endocrine peptides, some of which are secreted upon stimulation both in vitro and in vivo. Several VGF peptides, accounting for ∼20% of the VGF precursor sequence, have shown biological roles including regulation of food intake, energy balance, reproductive and homeostatic mechanisms, synaptic strengthening, long-term potentiation (LTP) and anti-depressant activity. From a further ∼50% of VGF derive multiple "fragments", largely identified in the human cerebro-spinal fluid by proteomic studies searching for disease biomarkers. These represent an important starting point for discovery of further VGF products relevant to neuronal brain functions, as well as to neurodegenerative and psychiatric disease conditions. A distinct feature of VGF peptides is their cell type specific diversity in all neuroendocrine organs studied so far. Selective differential profiles are found across the cell populations of pituitary, adrenal medulla and pancreatic islets, and in gastric neuroendocrine as well as some further mucosal cells, and are yet to be investigated in neuronal systems. At the same time, specific VGF peptide/s undergo selective modulation in response to organ or cell population relevant stimuli. Such pattern argues for a multiplicity of roles for VGF peptides, including endocrine functions, local intercellular communication, as well as the possible mediation of intracellular mechanisms.

The biology of spermatogenesis: the past, present and future

The physiological function of spermatogenesis in Caenorhabditis elegans, Drosophila melanogaster and mammals is to produce spermatozoa (1n, haploid) that contain only half of the genetic material of spermatogonia (2n, diploid). This half number of chromosomes from a spermatozoon will then be reconstituted to become a diploid cell upon fertilization with an egg, which is also haploid. Thus, genetic information from two parental individuals can be passed onto their offspring. Spermatogenesis takes place in the seminiferous epithelium of the seminiferous tubule, the functional unit of the mammalian testis. In mammals, particularly in rodents, the fascinating morphological changes that occur during spermatogenesis involving cellular differentiation and transformation, mitosis, meiosis, germ cell movement, spermiogenesis and spermiation have been well documented from the 1950s through the 1980s. During this time, however, the regulation of, as well as the biochemical and molecular mechanisms underlying these diverse cellular events occurring throughout spermatogenesis, have remained largely unexplored. In the past two decades, important advancements have been made using new biochemical, cell and molecular biology techniques to understand how different genes, proteins and signalling pathways regulate various aspects of spermatogenesis. These include studies on the differentiation of spermatogonia from gonocytes; regulation of spermatogonial stem cells; regulation of spermatogonial mitosis; regulation of meiosis, spermiogenesis and spermiation; role of hormones (e.g. oestrogens, androgens) in spermatogenesis; transcriptional regulation of spermatogenesis; regulation of apoptosis; cell-cell interactions; and the biology of junction dynamics during spermatogenesis. The impact of environmental toxicants on spermatogenesis has also become an urgent issue in the field in light of declining fertility levels in males. Many of these studies have helped investigators to understand important similarities, differences and evolutionary relationships between C. elegans, D. melanogaster and mammals relating to spermatogenesis. In this Special Issue of the Philosophical Transactions of the Royal Society B: Biological Sciences, we have covered many of these areas, and in this Introduction, we highlight the topic of spermatogenesis by examining its past, present and future.

Testicular cell junction: a novel target for male contraception

Even though various contraceptive methods are widely available, the number of unwanted pregnancies is still on the rise in developing countries, pressurizing the already resource limited nations. One of the major underlying reasons is the lack of effective, low cost, and safe contraceptives for couples. During the past decade, some studies were performed using animal models to decipher if the Sertoli-germ cell junction in the testis is a target for male fertility regulation. Some of these study models were based on the use of hormones and/or chemicals to disrupt the hypothalamic-pituitary-testicular axis (e.g., androgen-based implants or pills) and others utilized a panel of chemical entities or synthetic peptides to perturb spermatogenesis either reversibly or non-reversibly. Among them, adjudin, a potential male contraceptive, is one of the compounds exerting its action on the unique adherens junctions, known as ectoplasmic specializations, in the testis. Since the testis is equipped with inter-connected cell junctions, an initial targeting of one junction type may affect the others and these accumulative effects could lead to spermatogenic arrest. This review attempts to cover an innovative theme on how male infertility can be achieved by inducing junction instability and defects in the testis, opening a new window of research for male contraceptive development. While it will still take much time and effort of intensive investigation before a product can reach the consumable market, these findings have provided hope for better family planning involving men.

Adjudin targeting rabbit germ cell adhesion as a male contraceptive: a pharmacokinetics study

Adjudin (1-(2,4-dichlorobenzyl)-1H-indazole-3-carbohydrazide; formerly called AF-2364) has been shown to inhibit spermatogenesis by disrupting anchoring junctions at the Sertoligerm cell interface. This, in turn, leads to germ cell loss from the seminiferous epithelium, and transient infertility. Adjudin's efficacyin inhibiting spermatogenesis, the recovery of spermatogenesis after cessation of the drug, and side effects were examined in adult male Japanese rabbits. The pharmacokinetics profiles of adjudin in rabbits after oral administration and after intravenous injection were compared. Rabbits received 25 mg/kg adjudin once weekly for 4 consecutive weeks either by intravenous injection or by gavage. Vehicle-treated rabbits were used as controls. At 1, 2, 3, 4, and 8 weeks after treatment, testes were removed for microscopic examination to assess the status of spermatogenesis. Four weeks after intravenous cessation of adjudin, the recovery of spermatogenesis also was monitored. Blood was withdrawn after first administration to measure plasma concentrations of adjudin by high-performance liquid chromatography. Four weeks after intravenous treatment, examination of testis sections showed rapid exfoliation of elongated/elongating spermatids and the presence of large multinucleated cells; more than 95% of germ cells were absent from the seminiferous epithelium. Intravenous treatment showed a more severe disturbance of spermatogenesis compared with gavage treatment, which was correlated with bioavailability of the drug. The areas under the curve for intravenous injection and gavage were 20.11 +/- 1.90 and 2.23 +/- 0.45 mg x h x L(-1), respectively. These results illustrate the potential of adjudin as a male contraceptive, and the efficacy is associated with the bioavailability of the drug.

Anchoring junctions as drug targets: role in contraceptive development

In multicellular organisms, cell-cell interactions are mediated in part by cell junctions, which underlie tissue architecture. Throughout spermatogenesis, for instance, preleptotene leptotene spermatocytes residing in the basal compartment of the seminiferous epithelium must traverse the blood-testis barrier to enter the adluminal compartment for continued development. At the same time, germ cells must also remain attached to Sertoli cells, and numerous studies have reported extensive restructuring at the Sertoli-Sertoli and Sertoli-germ cell interface during germ cell movement across the seminiferous epithelium. Furthermore, the proteins and signaling cascades that regulate adhesion between testicular cells have been largely delineated. These findings have unveiled a number of potential "druggable" targets that can be used to induce premature release of germ cells from the seminiferous epithelium, resulting in transient infertility. Herein, we discuss a novel approach with the aim of developing a nonhormonal male contraceptive for future human use, one that involves perturbing adhesion between Sertoli and germ cells in the testis.

Regulation of cell junction dynamics by cytokines in the testis: a molecular and biochemical perspective

Studies in the past decade in the field have demonstrated the significance of cytokines in regulating epithelial and endothelial cell junctions including tight and anchoring junctions in multiple organs including the testis. There are mounting evidences in recent years that cytokines play a crucial role in the restructuring of junctions at the Sertoli-Sertoli and Sertoli-germ cell interface in the seminiferous epithelium during spermatogenesis. These earlier studies, however, were focused on the effects of cytokines in maintaining the steady-state protein levels of integral membrane proteins at the sites of the blood-testis barrier (BTB) and anchoring junctions at the Sertoli-Sertoli and Sertoli-germ cell interface, such as basal and apical ectoplasmic specialization, respectively. The molecular pathway(s) and/or mechanism(s) underlying these effects remained virtually unexplored until very recently. Herein, we summarize and provide some discussions on studies that focused on the role of cytokines in regulating junction restructuring events in epithelia from a molecular and biochemical perspective. Specifically, we use the adult rat or mouse testis as a model to highlight the significance of transcriptional and translational regulation. Specific areas of research that require further attentions are also highlighted.