A piggyBac-based TANGO GFP assay for high throughput screening of GPCR ligands in live cells.

BACKGROUND: GPCRs are considered essential for various physiological processes and have been the most productive drug targets. Therefore, development of the methods of GPCR ligands screening is a high priority for pharmaceutical industries and research institutions. METHODS: We developed a potential method (piggyBac-TANGO) based on the TANGO and PRESTO-TANGO assays. The system was optimized with a piggyBac transposon as a transgene vehicle, and eGFP was used as a reporter instead of luciferase. The assay was validated in the HEK 293T and U87-MG cell lines and antagonist activities of the compounds were assessed. The transgene copy number and long-term stability were evaluated by qPCR. Then, we performed a DRD2-targeted screening for natural products using the piggyBac-TANGO assay. RESULTS: The validation assay showed that using the piggyBac transposon as a transgene vehicle produced high signal-to-background ratio and stable readout confirmed by investigation of the transgene copy number and long-term stability. Use of eGFP instead of luciferase as a reporter enabled to create a high throughput system suitable for live cells. Moreover, the piggyBac-TANGO assay permitted versatile detection of antagonist activity of compounds and was not limited to a particular cell type. With the use of the piggyBac-TANGO assay, we have successfully identified a novel agonist of DRD2. CONCLUSION: Thus, the results indicate that the piggyBac-TANGO method is a user-friendly, robust and imaging-based assay that provides a novel approach to high throughput GPCR-targeted ligand screening and drug development.

Cyclin B2 can compensate for Cyclin B1 in oocyte meiosis I.

Mammalian oocytes are arrested at the prophase of the first meiotic division for months and even years, depending on species. Meiotic resumption of fully grown oocytes requires activation of M-phase-promoting factor (MPF), which is composed of Cyclin B1 and cyclin-dependent kinase 1 (CDK1). It has long been believed that Cyclin B1 synthesis/accumulation and its interaction with CDK1 is a prerequisite for MPF activation in oocytes. In this study, we revealed that oocyte meiotic resumption occurred in the absence of Cyclin B1. Ccnb1-null oocytes resumed meiosis and extruded the first polar body. Without Cyclin B1, CDK1 could be activated by up-regulated Cyclin B2. Ccnb1 and Ccnb2 double knockout permanently arrested the oocytes at the prophase of the first meiotic division. Oocyte-specific Ccnb1-null female mice were infertile due to failed MPF activity elevation and thus premature interphase-like stage entry in the second meiotic division. These results have revealed a hidden compensatory mechanism between Cyclin B1 and Cyclin B2 in regulating MPF and oocyte meiotic resumption.

Cilia loss sensitizes cells to transformation by activating the mevalonate pathway.

Although cilia loss and cell transformation are frequently observed in the early stage of tumorigenesis, the roles of cilia in cell transformation are unknown. In this study, disrupted ciliogenesis was observed in cancer cells and pancreatic cancer tissues, which facilitated oncogene-induced transformation of normal pancreatic cells (HPDE6C7) and NIH3T3 cells through activating the mevalonate (MVA) pathway. Disruption of ciliogenesis up-regulated MVA enzymes through ß catenin-T cell factor (TCF) signaling, which synchronized with sterol regulatory element binding transcription factor 2 (SREBP2), and the regulation of MVA by ß-catenin-TCF signaling was recapitulated in a mouse model of pancreatic ductal adenocarcinoma (PDAC) and human PDAC samples. Moreover, disruption of ciliogenesis by depleting Tg737 dramatically promoted tumorigenesis in the PDAC mouse model, driven by KrasG12D , which was inhibited by statin, an inhibitor of the MVA pathway. Collectively, this study emphasizes the crucial roles of cilia in governing the early steps of the transformation by activating the MVA pathway, suggesting that statin has therapeutic potential for pancreatic cancer treatment.

GGPP-Mediated Protein Geranylgeranylation in Oocyte Is Essential for the Establishment of Oocyte-Granulosa Cell Communication and Primary-Secondary Follicle Transition in Mouse Ovary.

Folliculogenesis is a progressive and highly regulated process, which is essential to provide ova for later reproductive life, requires the bidirectional communication between the oocyte and granulosa cells. This physical connection-mediated communication conveys not only the signals from the oocyte to granulosa cells that regulate their proliferation but also metabolites from the granulosa cells to the oocyte for biosynthesis. However, the underlying mechanism of establishing this communication is largely unknown. Here, we report that oocyte geranylgeranyl diphosphate (GGPP), a metabolic intermediate involved in protein geranylgeranylation, is required to establish the oocyte-granulosa cell communication. GGPP and geranylgeranyl diphosphate synthase (Ggpps) levels in oocytes increased during early follicular development. The selective depletion of GGPP in mouse oocytes impaired the proliferation of granulosa cells, primary-secondary follicle transition and female fertility. Mechanistically, GGPP depletion inhibited Rho GTPase geranylgeranylation and its GTPase activity, which was responsible for the accumulation of cell junction proteins in the oocyte cytoplasm and the failure to maintain physical connection between oocyte and granulosa cells. GGPP ablation also blocked Rab27a geranylgeranylation, which might account for the impaired secretion of oocyte materials such as Gdf9. Moreover, GGPP administration restored the defects in oocyte-granulosa cell contact, granulosa cell proliferation and primary-secondary follicle transition in Ggpps depletion mice. Our study provides the evidence that GGPP-mediated protein geranylgeranylation contributes to the establishment of oocyte-granulosa cell communication and then regulates the primary-secondary follicle transition, a key phase of folliculogenesis essential for female reproductive function.

Porcine Zygote Injection with Cas9/sgRNA Results in DMD-Modified Pig with Muscle Dystrophy.

Dystrophinopathy, including Duchenne muscle dystrophy (DMD) and Becker muscle dystrophy (BMD) is an incurable X-linked hereditary muscle dystrophy caused by a mutation in the DMD gene in coding dystrophin. Advances in further understanding DMD/BMD for therapy are expected. Studies on mdx mice and dogs with muscle dystrophy provide limited insight into DMD disease mechanisms and therapeutic testing because of the different pathological manifestations. Miniature pigs share similar physiology and anatomy with humans and are thus an excellent animal model of human disease. Here, we successfully achieved precise DMD targeting in Chinese Diannan miniature pigs by co-injecting zygotes with Cas9 mRNA and sgRNA targeting DMD. Two piglets were obtained after embryo transfer, one of piglets was identified as DMD-modified individual via traditional cloning, sequencing and T7EN1 cleavage assay. An examination of targeting rates in the DMD-modified piglet revealed that sgRNA:Cas9-mediated on-target mosaic mutations were 70% and 60% of dystrophin alleles in skeletal and smooth muscle, respectively. Meanwhile, no detectable off-target mutations were found, highlighting the high specificity of genetic modification using CRISPR/Cas9. The DMD-modified piglet exhibited degenerative and disordered phenotypes in skeletal and cardiac muscle, and declining thickness of smooth muscle in the stomach and intestine. In conclusion, we successfully generated myopathy animal model by modifying the DMD via CRISPR/Cas9 system in a miniature pig.

Altered protein prenylation in Sertoli cells is associated with adult infertility resulting from childhood mumps infection.

Mumps commonly affects children 5-9 yr of age, and can lead to permanent adult sterility in certain cases. However, the etiology of this long-term effect remains unclear. Mumps infection results in progressive degeneration of the seminiferous epithelium and, occasionally, Sertoli cell-only syndrome. Thus, the remaining Sertoli cells may be critical to spermatogenesis recovery after orchitis healing. Here, we report that the protein farnesylation/geranylgeranylation balance is critical for patients' fertility. The expression of geranylgeranyl diphosphate synthase 1 (GGPPS) was decreased due to elevated promoter methylation in the testes of infertile patients with mumps infection history. When we deleted GGPPS in mouse Sertoli cells, these cells remained intact, whereas the adjacent spermatogonia significantly decreased after the fifth postnatal day. The proinflammatory MAPK and NF-κB signaling pathways were constitutively activated in GGPPS(-/-) Sertoli cells due to the enhanced farnesylation of H-Ras. GGPPS(-/-) Sertoli cells secreted an array of cytokines to stimulate spermatogonia apoptosis, and chemokines to induce macrophage invasion into the seminiferous tubules. Invaded macrophages further blocked spermatogonia development, resulting in a long-term effect through to adulthood. Notably, this defect could be rescued by GGPP administration in EMCV-challenged mice. Our results suggest a novel mechanism by which mumps infection during childhood results in adult sterility.

The Heat-Induced Reversible Change in the Blood-Testis Barrier (BTB) Is Regulated by the Androgen Receptor (AR) via the Partitioning-Defective Protein (Par) Polarity Complex in the Mouse.

Scrotal hypothermia is essential for normal spermatogenesis, and temporal heat stress causes a reversible disruption of the blood-testis barrier (BTB). Previous studies have shown that AR expression in primary monkey Sertoli cells (SCs) was dramatically reduced after temporary heat treatment. However, the mechanisms underlying the heat-induced reversible disruption of the BTB, including whether it is directly regulated by the AR, remain largely unknown. In this study, we demonstrated that the AR acts upstream to regulate the heat-induced reversible change in the BTB in mice. When the AR was overexpressed in SCs using an adenovirus, the heat stress-induced down-regulation of BTB-associated proteins (Zonula occludens-1 (ZO-1), N-Cadherin, E-Cadherin, α-Catenin, and ß-Catenin) was partially rescued. AR knockdown by RNAi or treatment with flutamide (an AR antagonist) in SCs inhibited the recovery of BTB-associated protein expression after 43°C heat treatment for 30 min. The results of an in vivo AR antagonist injection experiment further showed that the recovery of BTB permeability induced by temporal heat stress was regulated by the AR. Furthermore, we observed that the co-localization and interactions of partitioning-defective protein (Par) 6-Par3-aPKC-Cdc42 polarity complex components were disrupted in both AR-knockdown and heat-induced SCs. AR overexpression in SCs prevented the disruption of these protein-protein interactions after heat treatment. AR knockdown or treatment with flutamide in SCs inhibited the restoration of these protein-protein interactions after heat treatment compared with heat treatment alone. Together, these results demonstrate that the AR plays a crucial role in the heat-induced reversible change in BTB via the Par polarity complex.

[Detection of apoptosis with gel eletrophoresis combined with computerized gel analysis system].

OBJECTIVE: To explore a new method for detecting cellular apoptosis. METHODS: Using routine electrophoresis assisted by computerized gel documentation analysis system(GDAS), apoptosis of the macrophages treated with dexamethasone was qualitatively and then quantitatively detected. RESULTS: Apoptosis occurred in the macrophages treated with dexamethasone, and DNA fragmentation of the apoptotic macrophages was visualized on 1% agarose gel electrophoresis. The apoptosis rates as determined by computerized GDAS were consistent with the results obtained from flow cytometry that showed typical apoptosis peak. CONCLUSION: Agarose gel electrophoresis assisted by computerized GDAS was relatively simple and less costly in qualitative and quantitative detection of apoptosis with precision.