Contact Inhibition Research Articles

Effect of serum starvation and contact inhibition on dermal fibroblast cell cycle synchronization in two species of wild felids and domestic cat

Abstract Cell cycle synchronization of donor cells is an important step in mammalian somatic cell nuclear transfer (SCNT). This study was designed to compare the efficiency of serum starvation (Ss) and contact inhibition (cI) on cell cycle synchronization of jaguarundi, manul, and domestic cat skin fibroblasts, in the production of G0/G1 cells suitable for SCNT in felids. Ss was performed after the growing (G) cells reached 40–50% (G50+Ss), 60–70% (G70+Ss) and full confluency (Fc), i.e. in association with cI (cI+Ss). Frozen-thawed cells were cultured to the given state of confluency (d0; controls), and subjected to Ss or cI for 1, 3, and 5 days (d). In manul, the effect of Ss on arresting fibroblasts in the G0/G1 phase was noted after just 1d of culture at G70 confluence, while G50+Ss and cI+Ss were effective after 5d of treatment. In jaguarundi, 1–5d of G50+Ss and 5d of G70+Ss increased the percentage of G0/G1 cells versus d0 (P<0.01), with 5d of G70+Ss producing more (P<0.05) quiescent cells than after the same period of G50+Ss, cI+Ss and cI. In the domestic cat, Ss was efficient only after 3 and 5d of G50+Ss. In all species, cI alone failed to increase the proportion of G0/G1 cells compared to d0, however in the domestic cat, 5d of cI was more efficient than the same period of G50+Ss. In jaguarundi, >93% of cells were already in G0/G1 phase at d0 of Fc, suggesting that culture to Fc could be also a valuable method for fibroblast cell cycle synchronization in this species. In contrast to cI, prolonged Ss generated cell loss and could induce apoptosis and/or necrosis. In conclusion, Ss was the more efficient method for skin fibroblast cell cycle synchronization at the G0/G1 phase in manul, jaguarundi and the domestic cat. The response of cells to the treatments was species-specific, depending on cell confluence and duration of culture. This research may find application in preparing donor karyoplasts for SCNT in felids.

Unfolding the journey of scaffold

Periodontal tissues can be destructed by chronic periodontal disease, which can lead to tooth loss. In support of the treatment for periodontally diseased tooth, various biomaterials have been applied starting as a contact inhibition membrane in the guided tissue regeneration that is the current gold standard in dental clinic. Recently, various biomaterials have been prepared in a form of tissue engineering scaffold to facilitate the regeneration of damaged periodontal tissues. From a physical substrate to support healing of a single type of periodontal tissue to multiphase/bioactive scaffold system to guide an integrated regeneration of periodontium, technologies for scaffold fabrication have emerged in the last years. This review covers the recent advancements in development of scaffolds designed for periodontal tissue regeneration and their efficacy tested in vitro and in vivo.

Loss of contact inhibition of locomotion in the absence of JAM-A promotes entotic cell engulfment

SummaryEntosis is a cell competition process during which tumor cells engulf other tumor cells. It is initiated by metabolic stress or by loss of matrix adhesion, and it provides the winning cell with resources derived from the internalized cell. Using micropatterns as substrates for single cell migration, we find that the depletion of the cell adhesion receptor JAM-A strongly increases the rate of entosis in matrix-adherent cells. The activity of JAM-A in suppressing entosis depends on phosphorylation at Tyr280, which is a binding site for C-terminal Src kinase, and which we have previously found to regulate tumor cell motility and contact inhibition of locomotion (CIL). Loss of JAM-A triggers entosis in matrix-adherent cells but not matrix-deprived cells. Our findings strongly suggest that the increased motility and the perturbed CIL response after the depletion of JAM-A promote entotic cell engulfment, and they link a dysregulation of CIL to entosis in breast cancer cells.

Functional Cyanine-Based PVA:PVP Polymers as Antimicrobial Tools toward Food and Health-Care Bacterial Infections.

The rising of multidrug-resistant bacteria and their associated proliferation as harmful microorganisms boosts the creation of new antibacterial surfaces and biomaterials with applications ranging from health to food packing. Herein, low-cost antibacterial PVA:PVP copolymers containing cyanine derivatives (1, 2, and 3) and their respective Cu2+ complexes are successfully obtained and tested against Gram-negative and Gram-positive bacteria. The possible application in food packing is addressed by covering the surface of typical paper mockups with the doped polymers. All dye-doped polymers present a broad-spectrum antibacterial effect against Gram-positive bacteria, especially for Bacillus cereus (B. cereus), Staphylococcus aureus (S. aureus), and methicillin-resistant S. aureus (MRSA) strains, with PVA:PVP@3 and PVA:PVP@3-Cu being the most effective. Moreover, polymers containing cyanine derivatives present interesting inhibition effects against Pseudomonas aeruginosa (P. aeruginosa), where the production of its characteristic blue/green virulent pigment is not observed. Of the coated paper mockups, PVA:PVP:paper@2 and PVA:PVP:paper@2-Cu are most effective against B. cereus and S. aureus, while PVA:PVP:paper@3 and PVA:PVP:paper@3-Cu are most effective against the MRSA strain. In these formulations, direct contact inhibition mechanisms appear to be more significant than diffusional mechanisms, due to cyanine release hindrance, making them very interesting and versatile platforms for medical and food applications.

Tenascin-C fibronectin D domain is involved in the fine-tuning of glial response to CNS injury in vitro.

Understanding processes that occur after injuries to the central nervous system is essential in order to gain insight into how the restoration of function can be improved. Extracellular glycoprotein tenascin-C (TnC) has numerous functions in wound healing process depending on the expression time, location, isoform and binding partners which makes it interesting to study in this context. We used an in vitro injury model, the mixed culture of cortical astrocytes and microglia, and observed that without TnC microglial cells tend to populate gap area in greater numbers and proliferate more, whereas astrocytes build up in the border region to promote faster gap closure. Alternatively spliced domain of TnC, fibronectin type III-like repeat D (FnD) strongly affected physiological properties and morphology of both astrocytes and microglia in this injury model. The rate of microglial proliferation in the injury region decreased significantly with the addition of FnD. Additionally, density of microglia also decreased, in part due to reduced proliferation, and possibly due to reduced migration and increased contact inhibition between enlarged FnD-treated cells. Overall morphology of FnD-treated microglia resembled the activated pro-inflammatory cells, and elevated expression of iNOS was in accordance with this phenotype. The effect of FnD on astrocytes was different, as it did not affect their proliferation, but stimulated migration of reactivated astrocytes into the scratched area 48 h after the lesion. Elevated expression and secretion of TNF-α and IL-1β upon FnD treatment indicated the onset of inflammation. Furthermore, on Western blots we observed increased intensity of precursor bands of β1 integrin and appearance of monomeric bands of P2Y12R after FnD treatment which substantiates and clarifies its role in cellular shape and motility changes. Our results show versatile functions of TnC and in particular FnD after injury, mostly contributing to ongoing inflammation in the injury region. Based on our findings, FnD might be instrumental in limiting immune cell infiltration, and promoting astrocyte migration within the injury region, thus influencing spaciotemporal organization of the wound and surrounding area.

Pharmacological Activation of Potassium Channel Kv11.1 with NS1643 Attenuates Triple Negative Breast Cancer Cell Migration by Promoting the Dephosphorylation of Caveolin-1.

The prevention of metastasis is a central goal of cancer therapy. Caveolin-1 (Cav-1) is a structural membrane and scaffolding protein shown to be a key regulator of late-stage breast cancer metastasis. However, therapeutic strategies targeting Cav-1 are still lacking. Here, we demonstrate that the pharmacological activation of potassium channel Kv11.1, which is uniquely expressed in MDA-MB-231 triple negative breast cancer cells (TNBCs) but not in normal MCF-10A cells, induces the dephosphorylation of Cav-1 Tyr-14 by promoting the Ca2+-dependent stimulation of protein tyrosine phosphatase 1B (PTP1B). Consequently, the dephosphorylation of Cav-1 resulted in its disassociation from β-catenin, which enabled the accumulation of β-catenin at cell borders, where it facilitated the formation of cell–cell adhesion complexes via interactions with R-cadherin and desmosomal proteins. Kv11.1 activation-dependent Cav-1 dephosphorylation induced with NS1643 also reduced cell migration and invasion, consistent with its ability to regulate focal adhesion dynamics. Thus, this study sheds light on a novel pharmacological mechanism of promoting Cav-1 dephosphorylation, which may prove to be effective at reducing metastasis and promoting contact inhibition.

Pressure and curvature control of the cell cycle in epithelia growing under spherical confinement.

SummaryMorphogenesis requires spatiotemporal regulation of proliferation, both by biochemical and mechanical cues. In epithelia, this regulation is called contact inhibition of proliferation, but disentangling biochemical from mechanical cues remains challenging. Here, we show that epithelia growing under confinement accumulate pressure that inhibits proliferation above a threshold value. During growth, epithelia spontaneously buckle, and cell proliferation is transiently reactivated within the fold. Reactivation of proliferation within folds correlated with the local reactivation of the mechano-sensing YAP/TAZ pathway. At late time points, when the pressure is highest, β-catenin activity increases. The threshold pressure increases when β-catenin is overactivated and decreases when β-catenin is inhibited. Altogether, our results suggest that different mechanical cues resulting from pressure inhibition of proliferation are at play through different mechano-sensing pathways: the β-catenin pathway sustains cell division under high pressure, and the YAP pathway senses local curvature.

Current Advancements in Corneal Cell-Based Therapy.

Corneal epithelial stem cells (CEpSCs) mostly reside at the limbal area and are responsible for tissue homeostasis throughout life. Once complete CEpSC deficiency occurs, regenerative medicine cell-based therapy using CEpSCs or their alternatives can provide successful clinical outcomes. Due to an improved understanding of CEpSCs and mucosal epithelial stem cells, major advancements have been made over the past few decades in in vivo and ex vivo cell-based ocular surface reconstruction therapies for the treatment of severe ocular surface diseases. New therapeutic concepts and clinical strategies are emerging for the treatment of corneal endothelial dysfunction. For example, unlike corneal epithelial cells, in vivo corneal endothelial cells (CECs) stop proliferating and are arrested in the G1 phase of the cell cycle due to cell-to-cell contact inhibition and exposure to a high concentration of transforming growth factor-beta in the aqueous humor. Thus, the production of CECs with good functionality in culture has consistently been difficult. To solve this problem, Rho-associated protein kinase inhibition has taken center stage, as it not only makes the production of human CECs in culture closely mimic the functional characteristics of in vivo healthy CECs possible but also helps sustain those biological properties. Thus, cultured human CEC injection therapy is now moving to the forefront for the treatment of corneal endothelial failure. Herein, we summarize key historical discoveries in corneal cell-based regenerative medicine and illustrate the concept of corneal cell therapy for the treatment of refractory corneal epithelial and endothelial diseases.

真核细胞运动接触抑制行为的力学-化学耦合模拟

Contact inhibition of locomotion (CIL) drives various biological phenomena, including cell dispersion, collective cell migration, and cancer invasion. Based on our previously proposed cell migration model with multilayered signaling cascades, a mechanical-chemical coupling model for CIL was developed by further incorporating cell-cell contact-dependent signaling pathways to guide the cytoskeleton remodeling. The cell structure model incorporates a discrete actin filament network within a cycle. The entire mathematical model is composed of nonlinear diffusion-reaction equations coupled with force-balance equations and solved numerically by the in-house built LBP-D1Q3 method. Numerical simulations indicated that the manifestation of distinct CIL behavior depends on the cooperation between FilGAP-FLNa and N-cadherin signaling pathways in terms of Rho GTPase signaling. After achieving a suitable inhibitory effect of FilGAP, the cells retain moderate polarity, which can be reversed in response to N-cadherin signaling, leading to normal CIL behavior. The lack of FilGAP transforms the cells to a fully polarized state, which is difficult to reverse, thus leading to the “bypass” behavior. The lack of N-cadherin signaling prevents cells from repolarizing in response to cell-cell contact, leading to static cell-cell adhesion. These simulations provide a theoretical basis for understanding the effect of contact inhibition signaling on cell migration.

Small-molecule inhibitor cocktail promotes the proliferation of pre-existing liver progenitor cells.

SummaryA recent study showed that a cocktail of three small molecules, Y-27632, A83-01, and CHIR99021 (YAC), converts mature hepatocytes (MHs) into proliferative bipotent cells that can be induced into MHs and cholangiocytes in rats. However, when we reproduced these experiments, it was found that bipotent cells may be derived from resident liver progenitor cells (LPCs), whose proliferative activity was promoted by YAC. A simple and efficient sorting scheme was also developed in this study to harvest high-purity and high-yield LPCs. The inducible bipotency of purified LPCs was verified; in addition, they were found to spontaneously differentiate into hepatocytes and cholangiocytes due to changes in proliferative status even without induction. Moreover, during the differentiation process, some hepatocytes spontaneously reconverted to LPCs under certain conditions, such as the release of contact inhibition. These findings may improve our understanding of LPCs and provide a cell source for regenerative medicine.

Abstract 858: Development of ultrasensitive split luciferase biosensors monitoring activity of the merlin tumor suppressor

Abstract Understanding features common to all forms of cancer is a vital component of treatment and research into malignant disease. All solid tumours share the ability to overcome contact inhibition of proliferation (CIP), the process by which intercellular contacts engage signalling to stop proliferation. Merlin, a tumour suppressor protein that is inactivated in a wide variety of cancers, plays a crucial role in CIP; merlin-deficient cells lose the ability to be contact-inhibited and subsequently form tumours. Although the role of merlin in cancer has been investigated extensively over the past 28 years, this protein has been notoriously difficult to study. To address this issue, we develop and utilize 2 split-luciferase biosensor systems that enable accurate quantification of merlin activity in real time. Merlin undergoes a conformational change that is functionally important in tumour suppression. Phosphorylation at a key C-terminal residue promotes transition of the protein from an open, active conformation to a closed, N-to-C terminal autoinhibited conformation. Therefore, monitoring this conformation change in real time could provide unique insights into merlin function. To do this, we apply NanoBiT split-luciferase technology to develop an intramolecular merlin biosensor (intra-Mer-BS). In brief, 2 split-luciferase components, LgBiT and SmBiT, are fused to the N- and C-terminus of merlin, respectively. Upon open-to-closed conformation change of merlin, LgBiT and SmBiT complement to reconstitute a functional luciferase and emit light. This enables accurate quantification of merlin’s functionally relevant conformation changes in real time. Importantly, cotransfection of the intra-Mer-BS alongside PAK1, an upstream merlin regulator that promotes transition to the closed conformation, significantly increases luminescent activity of the intra-Mer-BS, indicating that the biosensor faithfully reports on merlin’s conformation. Moreover, merlin has been shown to exert its tumour suppressive function through activation of LATS, the central mediator of the Hippo signalling pathway. In addition to the intra-Mer-BS, we develop and validate a NanoBiT biosensor to monitor the interaction between merlin and LATS (Mer-LATS-BS). This Mer-LATS-BS is used to quantify the effect of merlin activators and inhibitors on merlin/LATS tumour suppressive activity in cancer cells. In summary, we develop and validate 2 novel bioluminescent biosensors to monitor merlin’s conformation changes and activity in cancer cells. The intra-Mer-BS and Mer-LATS-BS provide real time information with high sensitivity and excellent reproducibility. Ultimately, these biosensors enable high throughput screening to discover novel upstream regulators of merlin in cancer and provide mechanistic insight into how contact inhibitive signalling is propagated through merlin and the Hippo pathway. Citation Format: Alexander J. Pipchuk, Xiaolong Yang. Development of ultrasensitive split luciferase biosensors monitoring activity of the merlin tumor suppressor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 858.

Abstract 5701: HDAC inhibition decreases YAP1 expression but parodoxically activates TEAD transcription by the AP-1 pathway in breast cancer

Abstract The Hippo pathway is an evolutionally conserved pathway that is crucial in numerous aspects of cell biology, including contact inhibition, cell density, and others. Hippo pathway is well reported to be dysregulated in multiple cancer types and plays important oncogenic roles in human cancers. In mammalian cells, YAP is regulated by a phosphorylated cascade mediated by the kinases MST1/2 and LATS1/2, known as the canonical Hippo pathway. These upstream kinases phosphorylate YAP/TAZ and leads to its cytosolic degradation. Perturbation of the Hippo pathway leads to YAP intranuclear translocation and downstream activation of target genes, inducing proliferative signals and thus initiating oncogenesis. Novel mechanism linking the hippo pathway to various oncogenic mechanisms are rapidly discovered and reported, further establishing the significance of this pathway and its role in cancer biology. Breast cancer is the top leading cause of cancer in women and poses a significant morbidity and economic burden on society. Hormone positive (defined as positivity of the estrogen receptor ER and/or the progesterone receptor PR) breast cancer composes 70% of breast cancer. Endocrine therapy, chemotherapy, and more recently, CDK4/6 inhibitors and PI3K inhibitors are currently approved strategies towards breast cancer. Histone deacetylase (HDAC) inhibitors have been FDA approved for several hematological cancers, and recently have shown inconsistent results in clinical trials for breast cancer. In our study, we demonstrate and characterize a link between HDAC inhibition and the Hippo pathway. We discover that HDAC inhibitors suppress YAP expression both transcriptionally and translationally. Paradoxically, we demonstrate that although YAP is downregulated, TEAD mediated transcription of downstream Hippo targets is activated. Mechanistically, HDAC inhibition leads to upregulation of the AP-1 transcriptional machinery that cooperates with TEAD to facilitate transcription. By RNA-seq, chromatin studies and CRISPR knockout studies, we confirm that HDAC inhibition have the ability to activate downstream of Hippo pathway, suggesting a possible mechanism for breast cancer resistance towards HDAC inhibitor. Co-targeting HDAC inhibition and AP-1 results in enhanced efficacy of HDAC inhibitors and may be a promising approach for development towards breast cancer. Citation Format: Ting-Yi Lin, Yi-Ru Tseng, Naikuan Wang, Ta-Chung Chao, Chun-Yu Liu, Ling-Ming Tseng, Jiun-I Lai. HDAC inhibition decreases YAP1 expression but parodoxically activates TEAD transcription by the AP-1 pathway in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5701.

Abstract 1001: Investigates the role of vesicle trafficking in E-cadherin dynamics in collective migrated colon cancer cells

Abstract Cell adherens junction plays an important role in cell communication and regulation. E-cadherin is an important protein as adherens junctions. Loss of E-cadherin leads to epithelial cells transit to mesenchymal cells. Studies has demonstrated that E-cadherin dominates cell contact inhibition, which plays an important role in cell growth, however, recent studies demonstrated collective cell migration required E-cadherin expression escaping cell growth inhibition is important in metastasis. E-cadherin dynamics has been shown to be regulated by vesicle trafficking, however, the detail mechanism of vesicle trafficking in collective cell migration is not clear. This study is investigating the relationship between the endocytosis mechanism of E-cadherin and its dynamic expression resulting in collective cell migration. The expression of E-cadherin was controlled by regulating the concentration of calcium and EDTA to observe its effect on cell-cell contact. Through Transmission electron microscope, immunofluorescence staining and western blotting to observe the relationship between vesicle trafficking and E-cadherin. Collective cell migration is analyzed by transwell assay. When calcium concentration was increased, the E-cadherin in cell-cell contacts became stronger. Conversely, when EDTA concentration was increased, the E-cadherin in the cell-cell contacts became weaker. Meanwhile, we found colocalization occurs in Rab5 and Rab11 with E-cadherin. Besides, intracellular E-cadherin transported to the lysosome for degradation was also observed. We identified the role of E-cadherin is regulated in endocytosis mechanism and at cell-cell contacts through different regulatory, which provides a basis for the future use of drugs to affect E-cadherin expression to inhibit collective cell migration. Citation Format: Hui Min Koo, Xiang-Ling Hou, Yu-Lin Li, Yi-Wen Lu, Viriya Adhiguna Winarso, Yu-Cheng Weng, Wei-Ting Chao. Investigates the role of vesicle trafficking in E-cadherin dynamics in collective migrated colon cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1001.

Abstract 2263: The role of E-Cadherin mediated cell division in promoting collective colon cancer cell migration

Abstract Collective cell migration is the cell cohort migrates toward the direction. Other than single cell migration, collective cell migration requires cell-cell connection with E-cadherin, however, E-cadherin is the epithelial marker in epithelial mesenchymal transition and acts as tumor suppressor function. Therefore, the role of E-cadherin in collective cell migration is still under investigated. In the collected cells, cell migration and cell division are coordinated for the cohort motility, the mechanism is still not clear. This study is to investigate the role of E-cadherin orientation in cell division dependent collective cell migration. Colorectal cancer cell line HT29 with epithelial morphology were used and treated with Cetuximab and Dasatinib to inhibit EGFR and Src activity. Cells were also incubated on fibronectin to monitor the matrix dependent environment. The polarity of E-cadherin distribution and cell contact inhibition were defined and detected by Immunofluorescence. The molecular expression of p-FAK, CDK4, and cell proliferation marker, Ki67 were revealed by Immunofluorescence confocal microscopy and Western blot. The collective cell migration is analyzed and compared by wound healing and transwell assay. In the results, the polarized distribution of E-cadherin in leading cells which revealed pFAK expression on the cell membrane was associated with Ki67 and CDK4 positive proliferated cells. When cells were grown on fibronectin, the proliferated cells in the leading were decreased. When cells were treated with cetuximab, the E-cadherin distribution were not changed and had fewer effect on cell migration. However, dasatinib treatment can modulate E-cadherin orientation and suppress cell proliferation and cell migration. These results suggested modulate E-cadherin orientation such as Src inhibition can be the potential treatment strategy in colon cancer Citation Format: Yu-Lin Li, Yu-Cheng Weng, Viriya Adhiguna Winarso, Yi-Wen Lu, Hui Min Koo, Xiang-Ling Hou, Kai-Yu Tseng, Wei-Ting Chao. The role of E-Cadherin mediated cell division in promoting collective colon cancer cell migration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2263.

A LONG-TERM 10G-HYPERGRAVITY EXPOSURE PROMOTES CELL-CELL CONTACTS AND REDUCES ADHESIVENESS TO A SUBSTRATE, MIGRATION, AND INVASIVENESS OF MCF-7HUMAN BREAST CANCER CELLS.

G-force is a fundamental force controlling human cells. Cancer is one of the 4major health challenges in the Space missions. Cancer in Space project evaluates the reaction of human cancer cells to the conditions of the space flights, including an exposure to high g-forces. Explore an impact of 10g force on the oncogenic properties of human breast adenocarcinoma cells MCF-7. Cells were exposed to 10g force for 10days, as part of a 6-week simulation of conditions of a space flight. Then the cells were cultured for one week under normal culture conditions, before performing tests. Cell proliferation, cell viability, cell-cell contact inhibition, migration, and invasiveness were measured. Immunoblotting was used to evaluate expression of proteins. Proliferation, cell-cell interaction and formation of 3D structures, migration, and invasiveness of cells exposed to 10g were compared to parental cells cultured at 1g condition. 10g exposed cells showed a higher propensity for cell-cell contact inhibitions and lower for 3-dimensional growth in dense culture. This correlated with the decrease of proliferation in a dense culture as compared to the parental cells. The decrease of migration, adherence to a surface, and invasiveness was observed for cells subjected to the hypergravity, as compared to the parental MCF-7cells. Enhanced expression of E-cadherin and phosphorylated pY576-FAK were observed in 10g exposed cells but no impact on the expression of Erk, pErk, FAK and p53was detected. The prolonged exposure of MCF-7cells to 10g force targets cell-cell and cell-substrate interactions.

Disruption of Toxoplasma gondii-Induced Host Cell DNA Replication Is Dependent on Contact Inhibition and Host Cell Type.

ABSTRACTThe protozoan Toxoplasma gondii is a highly successful obligate intracellular parasite that, upon invasion of its host cell, releases an array of host-modulating protein effectors to counter host defenses and further its own replication and dissemination. Early studies investigating the impact of T. gondii infection on host cell function revealed that this parasite can force normally quiescent cells to activate their cell cycle program. Prior reports by two independent groups identified the dense granule protein effector HCE1/TEEGR as being solely responsible for driving host cell transcriptional changes through its direct interaction with the cyclin E regulatory complex DP1 and associated transcription factors. Our group independently identified HCE1/TEEGR through the presence of distinct repeated regions found in a number of host nuclear targeted parasite effectors and verified its central role in initiating host cell cycle changes. Additionally, we report here the time-resolved kinetics of host cell cycle transition in response to HCE1/TEEGR, using the fluorescence ubiquitination cell cycle indicator reporter line (FUCCI), and reveal the existence of a block in S-phase progression and host DNA synthesis in several cell lines commonly used in the study of T. gondii. Importantly, we have observed that this S-phase block is not due to additional dense granule effectors but rather is dependent on the host cell line background and contact inhibition status of the host monolayer in vitro. This work highlights intriguing differences in the host response to reprogramming by the parasite and raises interesting questions regarding how parasite effectors differentially manipulate the host cell depending on the in vitro or in vivo context.IMPORTANCE Toxoplasma gondii chronically infects approximately one-third of the global population and can produce severe pathology in immunologically immature or compromised individuals. During infection, this parasite releases numerous host-targeted effector proteins that can dramatically alter the expression of a variety of host genes. A better understanding of parasite effectors and their host targets has the potential to not only provide ways to control infection but also inform us about our own basic biology. One host pathway that has been known to be altered by T. gondii infection is the cell cycle, and prior reports have identified a parasite effector, known as HCE1/TEEGR, as being responsible. In this report, we further our understanding of the kinetics of cell cycle transition induced by this effector and show that the capacity of HCE1/TEEGR to induce host cell DNA synthesis is dependent on both the cell type and the status of contact inhibition.

Immortalized human choroid plexus endothelial cells enable an advanced endothelial-epithelial two-cell type in vitro model of the choroid plexus

SummaryThe choroid plexus (CP) is a highly vascularized structure containing endothelial and epithelial cells located in the ventricular system of the central nervous system (CNS). The role of the fenestrated CP endothelium is under-researched and requires the generation of an immortalized CP endothelial cell line with preserved features. Transduction of primary human CP endothelial cells (HCPEnC) with the human telomerase reverse transcriptase (hTERT) resulted in immortalized HCPEnC (iHCPEnC), which grew as monolayer with contact inhibition, formed capillary-like tubes in Matrigel, and showed no colony growth in soft agar. iHCPEnC expressed pan-endothelial markers and presented characteristic plasmalemma vesicle-associated protein-containing structures. Cultivation of iHCPEnC and human epithelial CP papilloma (HIBCPP) cells on opposite sides of cell culture filter inserts generated an in vitro model with a consistently enhanced barrier function specifically by iHCPEnC. Overall, iHCPEnC present a tool that will contribute to the understanding of CP organ functions, especially endothelial-epithelial interplay.

Inhibiting ADAM10‐MMP14 Complex Blocks Cystogenesis of Kidney Epithelial Cells

BackgroundPolycystic kidney disease (PKD) is the most common genetic kidney disorder. It is characterized by the aberrant renal tubule epithelial cells proliferation leads to the formation of multiple fluid‐filled cysts, and it causes renal failure. Currently, kidney transplant or dialysis is the only effective treatment. A disintegrin‐like metalloproteinase 10 (ADAM10) and matrix metalloproteinase 14 (MMP14) are two major members in the superfamily of metalloproteinases that primarily cleave several cell membrane proteins and growth factors. Inhibition of ADAM10 activity reduces cystic growth of renal epithelial cells, and inhibition of MMP14 also reduces the number of cysts in the kidneys of rats with PKD. In our study, we propose to elucidate the unclear relationship between ADAM10 and MMP14 in the development of cystogenesis in kidney.MethodsMadin‐Darby Canine Kidney (MDCK) cells with stable expression of MMP14 and its mutants were developed and used in our study. MTT proliferation assay was used to measure cell growth. Immunoprecipitation and Western blots were used to determine physical association and proteinase activity. 3‐dimensional (3D) culture of MDCK cells was used to examine cell growth patterns.ResultsWe found that a unique ADAM10‐MMP14 complex forms in cell membrane. The hemopexin domain of MMP14 is essential for its association with ADAM10. Their interaction causes differential cleavage of cell membrane proteins, E‐cadherin and L1 cell adhesion molecule protein (L1CAM). In MDCK cells, only ADAM10 cleaves E‐cadherin but its cleavage is dependent on the active form of MMP14. In addition, both ADAM10 and MMP14 cleave L1CAM but inactive MMP14 blocks the ADAM10 cleavage of L1CAM. We tested the effects of ADAM10 and MMP14 interaction on cell proliferation and cystic growth. Ectopic expression of MMP14 increases cell proliferation and cystic growth of MDCK cells in a 3D culture matrix. Further, use of MMP14‐specific inhibitor NSC405020 or ectopic expression of a dominant‐negative form of MMP14 mutant also results in proper contact inhibition, and further promotes tubular growth of MDCK cells in 3D culture. Inhibition of ADAM10 with siRNA or enzymatic inhibitor GI254023X significantly reduces cell proliferation and promotes tubular growth. Combined use of GI254023X and NSC405020 results in a 73.4 ±8.23% decrease in cell proliferation compared to GI254023X, and 68.6 ± 6.84% decrease compared to NSC405020 alone. In 3D culture, MDCK‐MMP14 (ectopic expression of MMP14) cells form cystic growth only, but addition of both ADAM10 and MMP14 inhibitors leads to tubular growth only.ConclusionOur data identified the solid physical association of ADAM10 and MMP14. Their functional interaction causes differential cleavage of cell membrane proteins, E‐cadherin and L1CAM. Inhibition of ADAM10‐MMP14 complex blocks proliferation and the cystogenesis of of kidney epithelial cells. Individual ADAM10 or MMP14 inhibitors have been used in clinical trials for certain tumors, however, they have never been used together nor have been used in PKD treatments. Our results suggest the combination of ADAM10 and MMP14 inhibitors could be served as a novel effective therapeutic strategy of PKD.

Push or Pull? Cell Proliferation and Migration During Wound Healing

Wound healing of the skin is a complex process that is still not well-understood. Wound management is expensive for both individuals and the health system overall, and can reduce quality of life for patients. Given these significant socio-economic impacts, wound healing has long been a focus of scientific research. Recentin vivomouse studies have identified two key regions in wounded skin tissue: A non-proliferative leading edge that actively migrates into wounded space, and a proliferative hub in which cells have enhanced mitotic properties. This work uses mathematical and computational modelling to investigate the effect of changing the mechanical characteristics of cells in these two key regions. In this paper we explore what characteristics are sufficient for wound healing, particularly focusing on cell proliferation, since wounds are not able to repair successfully without sufficient levels of cell division. By considering contact inhibited proliferation, where small cells are unable to divide, we find that a quiescent region develops if the proliferative hub is able to grow over time, essentially limiting the number of cells that are able to divide. In contrast, if the size of the proliferative hub is kept below some threshold, then contact inhibition has a less significant role in wound repair. This work builds upon existing cell-based computational studies of wound healing and could be modified to investigate different stages of wound healing, impaired healing and wound treatments.

The relationship between the naked mole-rat and hyaluronic acid, as mediated by its receptor CD44: A Mini-Review

The life expectancy of the naked mole-rat (Heterocephalus glaber) is longer than that of other rodents. In NMR cells, the hyaluronic acid concentration is at a higher level. The extracellular matrix’s primary constituent is hyaluronic acid, and CD44 and RHMM are the receptors for hyaluronic acid in the cells. Hyaluronan synthases (HAS); HAS1, HAS2, and HAS3 are located in the plasma membrane and produce hyaluronic acid. Moreover, there are six types of hyaluronic degradation enzymes (Hyal-1, Hyal-2, Hyal-3, Hyal-4, and PH-20). Hyaluronic acid is known to have anti-cancerous effects and acts as a double-edged sword promoting cell senescence and protecting against cellular aging at the same time. NMR’s lengthy lifespan may probably be due to the high molecular weight of hyaluronic acid. INK4 isoforms (P16ink4a/b and pALTINK4a/b) and p27kip1 conferring on NMR a 2-way (early and regular respectively) defense mechanism make NMR more resistant to cancer cells than, humans and mice with only regular contact inhibition (regular (p27kip1). This study, therefore, aims to examine the existing molecular interactions within the NMR-HA-CD44 axis and the ability to confer cancer resistance to mammalian cells through INK4 isoforms gene transfer using the CRISPR method. A lot of potential thus exists in studying these relationships and the prospects for answering the yet unknowns in this area.