From embryonic development to human diseases: The functional role of caveolae/caveolin

CAVIN2/SDPR Functioned as a Tumor Suppressor in Lung Adenocarcinoma from Systematic Analysis of Caveolae-Related Genes and Experimental Validation

Background: Caveolae-Related Genes include caveolins and cavins, which are the main component of the fossa and, play important roles in a variety of physiological and pathological processes. Although increasing evidence indicated that caveolins (CAVs) and cavins (CAVINs) are involved in carcinogenesis and progression, their clinical significance and biological function in lung cancer are still limited. Methods: We investigated the expression of CAVs and CAVINs at transcriptional levels using Oncomine and Gene Expression Profiling Interactive Analysis. The protein and mRNA expression levels of CAVs and CAVINs were determined by the human protein atlas website and our surgically resected samples, respectively. The clinical value of prognostic prediction based on the expression of CAVs and CAVINs was also assessed. cBioPortal, GeneMANIA and STRING were used to analyze the molecular characteristics of CAVs and CAVINs in lung adenocarcinoma (LUAD) comprehensively. Finally, we investigated the effect of CAVIN2/SDPR (serum deprivation protein response) on LUAD cells with biological experiments in vitro. Results: The expression of CAV1/2 and CAVIN1/2/3 were significantly downregulated in LUAD and lung squamous cell carcinoma (LUSC). The patients with high expression of CAV1, CAV2, CAV3, CAVIN1 and CAVIN2/SDPR were tightly correlated with a better prognosis in LUAD, while no statistical significances in LUSC. Further, our results found that CAVIN2/SDPR can be identified as a prognostic biomarker independent of other CAVINs in patients with LUAD. Mechanically, the overexpression of CAVIN2/SDPR inhibited cell proliferation and migration owing to the cell apoptosis induction and cell cycle arrest at S phase in LUAD cells. Conclusions: CAVIN2/SDPR functioned as a tumor suppressor, and was able to serve as prognostic biomarkers in precision medicine of LUAD. Mechanically, overexpression of CAVIN2/SDPR inhibited cell proliferation by inducing cell apoptosis and S phase arrest in LUAD cells.

The mechanism and biomarker function of Cavin-2 in lung ischemia-reperfusion injury

BACKGROUND

Lung Ischemia Reperfusion injury(LIRI) is one of the most predominant complications of ischemic lung disease. Cavin-2 emerged as a regulator of a variety of cellular processes, including endocytosis, lipid homeostasis, signal transduction and tumorigenesis, but the function of Cavin-2 in LIRI is unknown. The purpose of this study was to determine the predictive potential of Cavin-2 in protecting lung ischemia-reperfusion injury and its corresponding mechanisms.

METHODS

We found the strong relationship between Cavin-2 and multiple immune-related genes by deep learning method. To reveal the mechanism of Cavin-2 in LIRI, the LIRI SD rat model was constructed to detect the expression of Cavin-2 in the lung tissue of SD rats after LIRI, and the expression of Cavin-2 in lung cell lines was also detected. The expression of IL-6, IL-10 and MDA in cells after Cavin-2 over-expression or knockdown was examined under hypoxic conditions. The expression levels of p-AKT, p-STAT3 and p-ERK1/2 were measured in over-expressing Cavin-2 cells under hypoxic-ischemia conditions, and then the corresponding blockers of AKT, STAT3 and ERK1/2 were given to verify, whether they play a protective role in LIRI.

RESULTS

After hypoxia, the expression of Cavin-2 in rat lung tissues was significantly increased, and the cellular activity and IL-10 in Cavin-2 over-expressing cells were significantly higher than that of the control group, while IL-6 and MDA were significantly lower than that of the control group, while the above results were reversed in Cavin-2 knockdown cells; Meanwhile, the phosphorylation levels of AKT, STAT3, and ERK1/2 were significantly increased in Cavin-2 over-expression cells after hypoxia. When AKT, STAT3, and ERK1/2 specific blockers were given, they lost their protective effect against LIRI.

CONCLUSIONS

Cavin-2 shows biomarker potential in protecting lung from ischemia-reperfusion injury through the survivor activating factor enhancement (SAFE) and reperfusion injury salvage kinase (RISK) pathway.

Editorial: Advances in genomic and genetic tools, and their applications for understanding embryonic development and human diseases

Significant advances have been recently made in the development of the genetic and genomic platforms. This has greatly contributed to a better understanding of gene expression and regulation machinery. Consequently, this led to considerable progress in unraveling evidence of the genotype-phenotype correlation between normal/abnormal embryonic development and human disease complexity. For example, advanced genomic tools such as next-generation sequencing, and microarray-based CGH have substantially helped in the identification of gene and copy number variants associated with diseases as well as in the discovery of causal gene mutations. In addition, bioinformatic analysis tools of genome annotation and comparison have greatly aided in data analysis for the interpretation of the genetic variants at the individual level. This has unlocked potential possibilities for real advances toward new therapies in personalized medicine for the targeted treatment of human diseases. However, each of these genomic and bioinformatics tools has its limitations and hence further efforts are required to implement novel approaches to overcome these limitations. It could be possible that the use of more than one platform for genotype-phenotype deep analysis is an effective approach to disentangling the cause and treatment of the disease complexities. Our research topic aimed at deciphering these complexities by shedding some light on the recent applications of the basic and advanced genetic/genomic and bioinformatics approaches. These include studying gene-gene, protein-protein, and gene-environment interactions. We, in addition, aimed at a better understanding of the link between normal/abnormal embryonic development and the cause of human disease induction.

A review of bioeffects induced by focused ultrasound combined with microbubbles on the neurovascular unit

Focused ultrasound combined with circulating microbubbles (FUS+MB) can transiently enhance blood-brain barrier (BBB) permeability at targeted brain locations. Its great promise in improving drug delivery to the brain is reflected by a rapidly growing number of clinical trials using FUS+MB to treat various brain diseases. As the clinical applications of FUS+MB continue to expand, it is critical to have a better understanding of the molecular and cellular effects induced by FUS+MB to enhance the efficacy of current treatment and enable the discovery of new therapeutic strategies. Existing studies primarily focus on FUS+MB-induced effects on brain endothelial cells, the major cellular component of BBB. However, bioeffects induced by FUS+MB expand beyond the BBB to cells surrounding blood vessels, including astrocytes, microglia, and neurons. Together these cell types comprise the neurovascular unit (NVU). In this review, we examine cell-type-specific bioeffects of FUS+MB on different NVU components, including enhanced permeability in endothelial cells, activation of astrocytes and microglia, as well as increased intraneuron protein metabolism and neuronal activity. Finally, we discuss knowledge gaps that must be addressed to further advance clinical applications of FUS+MB.

Prognostic significance and therapeutic implications of Caveolin-1 in gastrointestinal tract malignancies

Caveolin-1 (CAV1) is expressed in several solid tumors both in cancerous cells as well as in tumor stroma and is reported to be related to cancer progression, metastasis, therapy resistance and clinical outcomes. Many studies report contrasting functions of this protein depending on the tumor cell model, the tumor type, or the stage of cancer studied. This protein is reported to function both as tumor suppressor and as tumor promoter. In this review, we aim to summarize translational and clinical studies that provide evidence of the role of CAV1 in tumor progression and survival outcome focusing on tumors of the gastrointestinal (GI) tract. Towards this aim, a detailed search has been performed for studies on the expression and the role of CAV1 in oesophageal, gastric, colorectal, pancreatic cancer and cholangiocarcinoma prognosis. We also review and discuss the implication of CAV1 in the outcome of pharmacological interventions. We conclude that CAV1 has the potential to become an important prognostic, and possibly predictive, biomarker in GI malignancies. It may also become a novel target towards the development of improved cancer therapies. However, it is obvious that there remains a lack of consensus on important issues such as the methodologies and cut-off levels in caveolin assessment. This ultimately result in many studies being contradictory not only in terms of the role of CAV1 as a tumor-promoting or suppressing gene but also in terms of the tumor compartment in which the levels of this protein may be of clinical significance. Addressing these important technical issues, in conjunction with a further elucidation of the role of CAV1 in tumor formation and progression, will delineate the importance of CAV1 in prognostic and therapeutic perspectives.

Ultrastructure of Endothelial Cells of Myocardial Capillaries in Burn Septicotoxemia

We studied ultrastructure and vesicular structures in endothelial cells of myocardial micro-vessels in burn patients. Electron microscopy revealed a significant decrease in volume density of vesicular structures in the endotheliocytes of myocardial capillaries in patients with burn septicotoxemia. The observed structural signs of endothelial dysfunction revealed in this category of patients can be a promising area for further research and for the development of methods of pathogenetic correction of myocardial disorders in the case of burn injury.

Moderate mechanical stimulation rescues degenerative annulus fibrosus by suppressing caveolin-1 mediated pro-inflammatory signaling pathway

Mechanical loading can induce or antagonize the extracellular matrix (ECM) synthesis, proliferation, migration, and inflammatory responses of annulus fibrosus cells (AFCs), depending on the loading mode and level. Caveolin-1 (Cav1), the core protein of caveolae, plays an important role in cellular mechanotransduction and inflammatory responses. In the present study, we presented that AFCs demonstrated different behaviors when subjected to cyclic tensile strain (CTS) for 24 h at a magnitude of 0%, 2%, 5% and 12%, respectively. It was found that 5% CTS had positive effects on cell proliferation, migration and anabolism, while 12% CTS had the opposite effects. Besides, cells exposed to interleukin-1β stimulus exhibited an increase expression in inflammatory genes, and the expression of these genes decreased after exposure to moderate mechanical loading with 5% CTS. In addition, 5% CTS decreased the level of Cav1 and integrin β1 and exhibited anti-inflammatory effects. Moreover, the expression of integrin β1 and p-p65 increased in AFCs transfected with Cav1 plasmids. In vivo results revealed that moderate mechanical stimulation could recover the water content and morphology of the discs. In conclusion, moderate mechanical stimulation restrained Cav1-mediated signaling pathway and exhibited anti-inflammatory effects on AFCs. Together with in vivo results, this study expounds the underlying molecular mechanisms on the effect of moderate mechanical stimulation on intervertebral discs (IVDs) and may provide a new therapeutic strategy for the treatment of IVD degeneration.

Caveolae as Potential Hijackable Gates in Cell Communication

Caveolae are membrane microdomains described in many cell types involved in endocytocis, transcytosis, cell signaling, mechanotransduction, and aging. They are found at the interface with the extracellular environment and are structured by caveolin and cavin proteins. Caveolae and caveolins mediate transduction of chemical messages via signaling pathways, as well as non-chemical messages, such as stretching or shear stress. Various pathogens or signals can hijack these gates, leading to infectious, oncogenic and even caveolin-related diseases named caveolinopathies. By contrast, preclinical and clinical research have fallen behind in their attempts to hijack caveolae and caveolins for therapeutic purposes. Caveolae involvement in human disease is not yet fully explored or understood and, of all their scaffold proteins, only caveolin-1 is being considered in clinical trials as a possible biomarker of disease. This review briefly summarizes current knowledge about caveolae cell signaling and raises the hypothesis whether these microdomains could serve as hijackable “gatekeepers” or “gateways” in cell communication. Furthermore, because cell signaling is one of the most dynamic domains in translating data from basic to clinical research, we pay special attention to translation of caveolae, caveolin, and cavin research into clinical practice.

Caveolin 1 is required for axonal outgrowth of motor neurons and affects Xenopus neuromuscular development

Caveolins are essential structural proteins driving the formation of caveolae, specialized invaginations of the plasma membrane. Loss of Caveolin-1 (Cav1) function in mice causes distinct neurological phenotypes leading to impaired motor control, however, the underlying developmental mechanisms are largely unknown. In this study we find that loss-of-function of Xenopus Cav1 results in a striking swimming defect characterized by paralysis of the morphants. High-resolution imaging of muscle cells revealed aberrant sarcomeric structures with disorganized actin fibers. As cav1 is expressed in motor neurons, but not in muscle cells, the muscular abnormalities are likely a consequence of neuronal defects. Indeed, targeting cav1 Morpholino oligonucleotides to neural tissue, but not muscle tissue, disrupts axonal outgrowth of motor neurons and causes swimming defects. Furthermore, inhibition of voltage-gated sodium channels mimicked the Cav1 loss-of-function phenotype. In addition, analyzing axonal morphology we detect that Cav1 loss-of-function causes excessive filopodia and lamellipodia formation. Using rescue experiments, we show that the Cav1 Y14 phosphorylation site is essential and identify a role of RhoA, Rac1, and Cdc42 signaling in this process. Taken together, these results suggest a previously unrecognized function of Cav1 in muscle development by supporting axonal outgrowth of motor neurons.

Caveolin-1 promotes trophoblast cell invasion through the focal adhesion kinase (FAK) signalling pathway during early human placental development

Normal implantation and placental development depend on the appropriate differentiation and invasion of trophoblast cells. Inadequate trophoblast cell invasion results in pregnancy-related disorders, which endanger both mother and fetus; however, the mechanism of early placental development has not been fully explained. In this study we conducted gene expression profile analysis using mouse placental tissues at different developmental stages (embryonic day (E)7.5, E14.5 and E19.5) using series tests of cluster (STC) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analyses. Focal adhesion kinase (FAK) signalling pathway-related gene expression levels were verified using quantitative reverse transcription polymerase chain reaction and western blot. The results showed that caveolin-1 (Cav1) was downregulated in the placenta of unexplained spontaneous abortion subjects compared with that of induced abortion. Furthermore, by modulating CAV1 expression levels, CAV1 was shown to promote human trophoblast cell proliferation, migration and invasion by activating the FAK signalling pathway. These results indicate that CAV1 and the FAK signalling pathway are crucial for early placental development, which sheds new light on our understanding of the mechanisms of human trophoblast cell invasion and early development of the placenta.

Caveolae and Lipid Rafts in Endothelium: Valuable Organelles for Multiple Functions

Caveolae are flask-shaped invaginations of the plasma membrane found in numerous cell types and are particularly abundant in endothelial cells and adipocytes. The lipid composition of caveolae largely matches that of lipid rafts microdomains that are particularly enriched in cholesterol, sphingomyelin, glycosphingolipids, and saturated fatty acids. Unlike lipid rafts, whose existence remains quite elusive in living cells, caveolae can be clearly distinguished by electron microscope. Despite their similar composition and the sharing of some functions, lipid rafts appear more heterogeneous in terms of size and are more dynamic than caveolae. Following the discovery of caveolin-1, the first molecular marker as well as the unique scaffolding protein of caveolae, we have witnessed a remarkable increase in studies aimed at investigating the role of these organelles in cell functions and human disease. The goal of this review is to discuss the most recent studies related to the role of caveolae and caveolins in endothelial cells. We first recapitulate the major embryological processes leading to the formation of the vascular tree. We next discuss the contribution of caveolins and cavins to membrane biogenesis and cell response to extracellular stimuli. We also address how caveolae and caveolins control endothelial cell metabolism, a central mechanism involved in migration proliferation and angiogenesis. Finally, as regards the emergency caused by COVID-19, we propose to study the caveolar platform as a potential target to block virus entry into endothelial cells.

Fungal allergen-induced IL-33 secretion involves cholesterol-dependent, VDAC-1-mediated ATP release from the airway epithelium

KEY POINTS

Alternaria aeroallergens induce the release of ATP from human bronchial epithelial (HBE) cells by activating a conductive pathway involving voltage-dependent anion channel-1 (VDAC-1) and by exocytosis of ATP localized within membrane vesicles. Inhibition of VDAC-1 blocked Alternaria-evoked Ca²⁺ uptake across the plasma membrane of HBE cells and interleukin (IL)-33 release into the extracellular media. Reducing cholesterol content with a cholesterol scavenger (β-methylcyclodextrin) or statin compound (simvastatin) blocked ATP and IL-33 release by lowering the expression of VDAC-1 in the plasma membrane. Pretreatment with simvastatin for 24 h also inhibited the increase in tight junction macromolecule permeability that occurs following Alternaria exposure. These results establish a novel role for VDAC-1 as a mechanism underlying ATP release induced by fungal allergens and suggests a possible therapeutic use for cholesterol lowering compounds in reducing Alternaria-stimulated allergic inflammation.

ABSTRACT

Human bronchial epithelial (HBE) cells exposed to allergens derived from the common saprophytic fungus, Alternaria alternata release ATP, which in turn stimulates P2X₇ receptor-mediated Ca²⁺ uptake across the plasma membrane. The subsequent increase in intracellular calcium concentration induces proteolytic processing and secretion of interleukin (IL)-33, a critical cytokine involved in the initiation of allergic airway inflammation. A major objective of the present study was to identify the mechanism responsible for conductive ATP release. The results show that pretreatment of HBE cells with inhibitors of the voltage-dependent anion channel-1 (VDAC-1) or treatment with a VDAC-1 selective blocking antibody or silencing mRNA expression of the channel by RNA interference, inhibit Alternaria-evoked ATP release. Moreover, inhibition of VDAC-1 channel activity or reducing protein expression blocked the secretion of IL-33. Similarly, reducing the cholesterol content of HBE cells with simvastatin or the cholesterol scavenger β-methylcyclodextrin also blocked ATP release and IL-33 secretion by decreasing the level of VDAC-1 expression in the plasma membrane. In addition, simvastatin inhibited the increase in tight junction macromolecule permeability that was previously observed after Alternaria exposure. These results demonstrate a novel function for VDAC-1 as the conductive mechanism responsible for Alternaria-induced ATP release, an essential early step in the processing, mobilization and secretion of IL-33 by the airway epithelium. Furthermore, the simvastatin-evoked reduction of VDAC-1 expression in the plasma membrane, suggests the possibility that cholesterol lowering compounds may be beneficial in alleviating allergic airway inflammation induced by fungal allergens.

Effects of Electrical Stimulation on Stem Cells

Recent interest in developing new regenerative medicine- and tissue engineering-based treatments has motivated researchers to develop strategies for manipulating stem cells to optimize outcomes in these potentially, game-changing treatments. Cells communicate with each other, and with their surrounding tissues and organs via electrochemical signals. These signals originate from ions passing back and forth through cell membranes and play a key role in regulating cell function during embryonic development, healing, and regeneration. To study the effects of electrical signals on cell function, investigators have exposed cells to exogenous electrical stimulation and have been able to increase, decrease and entirely block cell proliferation, differentiation, migration, alignment, and adherence to scaffold materials. In this review, we discuss research focused on the use of electrical stimulation to manipulate stem cell function with a focus on its incorporation in tissue engineering-based treatments.

Multifaceted Roles of Caveolin-1 in Lung Cancer: A New Investigation Focused on Tumor Occurrence, Development and Therapy

Lung cancer is one of the most common and malignant cancers with extremely high morbidity and mortality in both males and females. Although traditional lung cancer treatments are fast progressing, there are still limitations. Caveolin-1 (Cav-1), a main component of caveolae, participates in multiple cellular events such as immune responses, endocytosis, membrane trafficking, cellular signaling and cancer progression. It has been found tightly associated with lung cancer cell proliferation, migration, apoptosis resistance and drug resistance. In addition to this, multiple bioactive molecules have been confirmed to target Cav-1 to carry on their anti-tumor functions in lung cancers. Cav-1 can also be a predictor for lung cancer patients’ prognosis. In this review, we have summarized the valuable research on Cav-1 and lung cancer in recent years and discussed the multifaceted roles of Cav-1 on lung cancer occurrence, development and therapy, hoping to provide new insights into lung cancer treatment.

Ultrastructural Organization of Uveal Melanoma Stromal Cells

Typical blood capillaries and vessels in uveal melanoma were shown and different types of uveal melanoma stromal cells were determined by electron microscopy and immunohistochemical analysis. Macrophages, fibroblasts of varying degrees of differentiation and endothelial-like cells with numerous caveolae in the cytoplasm were found in the channels of the extracellular matrix surrounding accumulations of tumor cells. The presence local structures positively stained for markers of the blood and lymphatic vessels (CD31 and podoplanin) in channels of the extracellular matrix suggests that the described endothelial-like cells can be the structural basis for blood and lymphatic vessels of the tumor.

Ascidian caveolin induces membrane curvature and protects tissue integrity and morphology during embryogenesis

Cell morphology and tissue integrity are essential for embryogenesis. Caveolins are membrane proteins that induce the formation of surface pits called caveolae that serve as membrane reservoirs for cell and tissue protection during development. In vertebrates, caveolin 1 (Cav1) and caveolin 3 (Cav3) are required for caveola formation. However, the formation of caveola and the function of caveolins in invertebrates are largely unknown. In this study, three caveolins, Cav-a, Cav-b, and CavY, are identified in the genome of the invertebrate chordate Ciona spp. Based on phylogenetic analysis, Cav-a is found to be closely related to the vertebrate Cav1 and Cav3. In situ hybridization shows that Cav-a is expressed in Ciona embryonic notochord and muscle. Cell-free experiments, model cell culture systems, and in vivo experiments demonstrate that Ciona Cav-a has the ability to induce membrane curvature at the plasma membrane. Knockdown of Cav-a in Ciona embryos causes loss of invaginations in the plasma membrane and results in the failure of notochord elongation and lumenogenesis. Expression of a dominant-negative Cav-a point mutation causes cells to change shape and become displaced from the muscle and notochord to disrupt tissue integrity. Furthermore, we demonstrate that Cav-a vesicles show polarized trafficking and localize at the luminal membrane during notochord lumenogenesis. Taken together, these results show that the invertebrate chordate caveolin from Ciona plays crucial roles in tissue integrity and morphology by inducing membrane curvature and intracellular vesicle trafficking during embryogenesis.

Caveolae: The FAQs

Caveolae are an abundant, but enigmatic, plasma membrane feature of vertebrate cells. In this brief commentary, the authors attempt to answer some key questions related to the formation and function of caveolae based on round-table discussions at the first EMBO Workshop on Caveolae held in France in May 2019.

Caveolae-mediated effects of TNF-α on human skeletal muscle cells

Chronic diseases are characterized by the production of pro-inflammatory cytokines such than TNF-α and are frequently correlated with muscle wasting conditions. Among the pleiotropic effects of TNF-α within the cell, its binding to TNFR1 receptor has been shown to activate sphingomyelinases leading to the production of ceramides. Sphingomyelinases and TNF receptor have been localized within caveolae which are specialized RAFT enriched in cholesterol and sphingolipids. Because of their inverted omega shape, maintained by the oligomerization of specialized proteins, caveolins and cavins, caveolae serve as membrane reservoir therefore providing mechanical protection to plasma membranes. Although sphingolipids metabolites, caveolins and TNF-α/TNFR1 have been shown to independently interfere with muscle physiology, no data have clearly demonstrated their concerted action on muscle cell regeneration. In this context, our study aimed at studying the molecular mechanisms induced by TNF-α at the level of caveolae in LHCN-M2 human muscle satellite cells. Here we showed that TNF-α-induced production of ROS and nSMase activation requires caveolin. More strikingly, we have demonstrated that TNF-α induces the formation of additional caveolae at the plasma membrane of myoblasts. Furthermore, TNF-α prevents myoblast fusion suggesting that inflammation could modulate caveolae organization/function and satellite cell function.

Uptake and transport of pullulan acetate nanoparticles in the BeWo b30 placental barrier cell model

INTRODUCTION

Nanomedicine has shown a great potential in perinatal medicine because of its characteristics of sustained, controlled release and targeting ability; on the other hand, it may also lead to unexpected toxicities such as embryotoxicity and even malformation after crossing the placental barrier, but data concerning transplacental transport are scarce. Pullulan acetate (PA) nanoparticles (NPs) are a promising nanocarrier derived from natural polysaccharide; however, their transplacental transport ability and mechanism are unknown.

MATERIALS AND METHODS

In this study, fluorescein isothiocyanate (FITC) conjugated PA (PA-FITC) was synthesized. PA-FITC NPs were characterized by dynamic light scattering, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The cytotoxicity of PA-FITC NPs at concentrations of 15, 30, 60, 125, 250, 500, 1,000 and 2,000 μg/mL was studied by cell counting kit-8. The human chorionic gonadotrophin (HCG) cytokine assay was conducted to evaluate the biological function of BeWo b30 cells. Endocytic mechanisms of PA-FITC NPs were investigated via fluorescence analysis. The monolayer properties were characterized by TEM, tight junction staining, transepithelial electrical resistance and fluorescein sodium transportation. The transport ability was measured in the cell based transwell model by confocal imaging and SEM.

RESULTS

PA-FITC NPs were almost spherical shape with a size range of 200-300 nm. Cell viability of BeWo b30 cells was up to 100% in all groups. The concentrations of HCG increased with increasing numbers of cells and culture time, which showed the good biological function of BeWo b30 cells. PA-FITC NPs were rapidly endocytosed through caveolae-mediated endocytosis and pinocytosis, with uptake inhibition rates with nystatin (NY) and colchicines (Col) of 55% and 51% respectively. BeWo b30 cell monolayer was formed over 5 days. PA-FITC NPs were found in the cytoplasm of cells on the transwell membranes; while some NPs were found in the basolateral (fetal) compartment over 24 h.

CONCLUSION

In summary, PA-FITC NPs are nontoxic, can cross the blood-placental barrier, and show mainly internalization to BeWo b30 cells through caveolae-mediated endocytosis and pinocytosis pathways, major via the former pathway. The results could benefit the adjustment and control of the transplacental transport of nanomedicines.

In vitro gentamicin exposure alters caveolae protein profile in cochlear spiral ligament pericytes

Background

The aminoglycoside antibiotic gentamicin is an ototoxic drug and has been used experimentally to investigate cochlear damage induced by noise.We have investigated the changes in the protein profile associated with caveolae in gentamicin treated and untreated spiral ligament (SL) pericytes, specialized cells in the blood labyrinth barrier of the inner ear microvasculature. Pericytes from various microvascular beds express caveolae, protein and cholesterol rich microdomains, which can undergo endocytosis and transcytosis to transport small molecules in and out the cells. A different protein profile in transport-specialized caveolae may induce pathological changes affecting the integrity of the blood labyrinth barrier and ultimately contributing to hearing loss.

Method

Caveolae isolation from treated and untreated cells is achieved through ultracentrifugation of the lysates in discontinuous gradients. Mass spectrometry (LC-MS/MS) analysis identifies the proteins in the two groups. Proteins segregating with caveolae isolated from untreated SL pericytes are then compared to caveolae isolated from SL pericytes treated with the gentamicin for 24 h. Data are analyzed using bioinformatic tools.

Results

The caveolae proteome in gentamicin treated cells shows that 40% of total proteins are uniquely associated with caveolae during the treatment, and 15% of the proteins normally associated with caveolae in untreated cell are suppressed. Bioinformatic analysis of the data shows a decreased expression of proteins involved in genetic information processing, and an increase in proteins involved in metabolism, vesicular transport and signal transduction in gentamicin treated cells. Several Rab GTPases proteins, ubiquitous transporters, uniquely segregate with caveolae and are significantly enriched in gentamicin treated cells.

Conclusion

We report that gentamicin exposure modifies protein profile of caveolae from SL pericytes. We identified a pool of proteins which are uniquely segregating with caveolae during the treatment, mainly participating in metabolic and biosynthetic pathways, in transport pathways and in genetic information processing. Finally, we show for the first time proteins associated with caveolae SL pericytes linked to nonsyndromic hearing loss.

Renal carcinoma/kidney progenitor cell chimera organoid as a novel tumorigenesis gene discovery model

Three-dimensional (3D) organoids provide a new way to model various diseases, including cancer. We made use of recently developed kidney-organ-primordia tissue-engineering technologies to create novel renal organoids for cancer gene discovery. We then tested whether our novel assays can be used to examine kidney cancer development. First, we identified the transcriptomic profiles of quiescent embryonic mouse metanephric mesenchyme (MM) and of MM in which the nephrogenesis program had been induced ex vivo. The transcriptome profiles were then compared to the profiles of tumor biopsies from renal cell carcinoma (RCC) patients, and control samples from the same kidneys. Certain signature genes were identified that correlated in the developmentally induced MM and RCC, including components of the caveolar-mediated endocytosis signaling pathway. An efficient siRNA-mediated knockdown (KD) of Bnip3, Gsn, Lgals3, Pax8, Cav1, Egfr or Itgb2 gene expression was achieved in mouse RCC (Renca) cells. The live-cell imaging analysis revealed inhibition of cell migration and cell viability in the gene-KD Renca cells in comparison to Renca controls. Upon siRNA treatment, the transwell invasion capacity of Renca cells was also inhibited. Finally, we mixed E11.5 MM with yellow fluorescent protein (YFP)-expressing Renca cells to establish chimera organoids. Strikingly, we found that the Bnip3-, Cav1- and Gsn-KD Renca-YFP+ cells as a chimera with the MM in 3D organoid rescued, in part, the RCC-mediated inhibition of the nephrogenesis program during epithelial tubules formation. Altogether, our research indicates that comparing renal ontogenesis control genes to the genes involved in kidney cancer may provide new growth-associated gene screens and that 3D RCC-MM chimera organoids can serve as a novel model with which to investigate the behavioral roles of cancer cells within the context of emergent complex tissue structures.

Editor’s Choice: Chimeras between embryonic kidney cells and renal carcinoma cells serve as a novel model to assay the roles of co-regulated genes in kidney development and renal carcinogenesis.

Identification and characterization of molluscan caveolin-1 ortholog from Haliotis discus discus: Possible involvement in embryogenesis and host defense mechanism against pathogenic stress

Caveolins are principal membrane proteins of caveolae that play a central role in signal transduction, substrate transport, and membrane trafficking in various cell types. Numerous studies have reported the crucial role of caveolin-1 (CAV1) in response to invading microbes; yet, very little is known about molluscan CAV1. In this study, we identified and characterized CAV1 ortholog from the disk abalone, Haliotis discus discus (HdCAV1). The cDNA sequence of HdCAV1 is 826 bp long and encodes a 127-amino acid polypeptide. Characteristic caveolin superfamily domain (Glu³ - Lys¹²⁶) and two possible transmembrane domains (Cys⁴⁸ - Tyr⁶⁷ and Ile¹⁰³ - Phe¹²⁰) were identified in the HdCAV1 protein. Homology analysis revealed that HdCAV1 shared higher identity (>47%) with molluscans, but lower identity with other species. Phylogenetic tree constructed by the neighbor-joining (NJ) method revealed a distinct evolutionary pathway for molluscans. Transcriptional analysis by SYBR Green qPCR showed the highest expression of HdCAV1 mRNA in late veliger stage, as compared to that in other embryonic developmental stages of disk abalone. In adult animals, gill tissue showed highest HdCAV1 transcript levels under normal physiological condition. Stimulations with two bacteria (Vibrio parahaemolyticus and Listeria monocytogenes), viral hemorrhagic septicemia virus, and two pathogen-associated molecular patterns (LPS and poly I:C) significantly modulated the expression of HdCAV1 transcripts. Collectively, these data suggest that CAV1 plays an important role in embryogenesis and host immune defense in disk abalone.

Altered expression and modulation of the two-pore-domain (K2P) mechanogated potassium channel TREK-1 in overactive human detrusor

Detrusor overactivity (DO) is the abnormal response of the urinary bladder to physiological stretch during the filling phase of the micturition cycle. The mechanisms of bladder smooth muscle compliance upon the wall stretch are poorly understood. We previously reported that the function of normal detrusor is regulated by TREK-1, a member of the mechanogated subfamily of two-pore-domain potassium (K_2P) channels. In the present study, we aimed to identify the changes in expression and function of TREK-1 channels under pathological conditions associated with DO, evaluate the potential relationship between TREK-1 channels and cytoskeletal proteins in the human bladder, and test the possibility of modulation of TREK-1 channel expression by small RNAs. Expression of TREK-1 channels in DO specimens was 2.7-fold decreased compared with control bladders and was associated with a significant reduction of the recorded TREK-1 currents. Isolated DO muscle strips failed to relax when exposed to a TREK-1 channel opener. Immunocytochemical labeling revealed close association of TREK-1 channels with cell cytoskeletal proteins and caveolins, with caveolae microdomains being severely disrupted in DO specimens. Small activating RNA (saRNA) tested in vitro provided evidence that expression of TREK-1 protein could be partially upregulated. Our data confirmed a significant downregulation of TREK-1 expression in human DO specimens and provided evidence of close association between the channel, cell cytoskeleton, and caveolins. Upregulation of TREK-1 expression by saRNA could be a future step for the development of in vivo pharmacological and genetic approaches to treat DO in humans.