Calponin 3 regulates actin cytoskeleton rearrangement in trophoblastic cell fusion

Mechanoregulation and function of calponin and transgelin

It is well known that chemical energy can be converted to mechanical force in biological systems by motor proteins such as myosin ATPase. It is also broadly observed that constant/static mechanical signals potently induce cellular responses. However, the mechanisms that cells sense and convert the mechanical force into biochemical signals are not well understood. Calponin and transgelin are a family of homologous proteins that participate in the regulation of actin-activated myosin motor activity. An isoform of calponin, calponin 2, has been shown to regulate cytoskeleton-based cell motility functions under mechanical signaling. The expression of the calponin 2 gene and the turnover of calponin 2 protein are both under mechanoregulation. The regulation and function of calponin 2 has physiological and pathological significance, as shown in platelet adhesion, inflammatory arthritis, arterial atherosclerosis, calcific aortic valve disease, post-surgical fibrotic peritoneal adhesion, chronic proteinuria, ovarian insufficiency, and tumor metastasis. The levels of calponin 2 vary in different cell types, reflecting adaptations to specific tissue environments and functional states. The present review focuses on the mechanoregulation of calponin and transgelin family proteins to explore how cells sense steady tension and convert the force signal to biochemical activities. Our objective is to present a current knowledge basis for further investigations to establish the function and mechanisms of calponin and transgelin in cellular mechanoregulation.

Loss of Calponin 2 causes premature ovarian insufficiency in mice

BACKGROUND

Premature ovarian insufficiency (POI) is a condition defined as women developing menopause before 40 years old. These patients display low ovarian reserve at young age and difficulties to conceive even with assisted reproductive technology. The pathogenesis of ovarian insufficiency is not fully understood. Genetic factors may underlie most of the cases. Actin cytoskeleton plays a pivotal role in ovarian folliculogenesis. Calponin 2 encoded by the Cnn2 gene is an actin associated protein that regulates motility and mechanical signaling related cellular functions.

RESULTS

The present study compared breeding of age-matched calponin 2 knockout (Cnn2-KO) and wild type (WT) mice and found that Cnn2-KO mothers had significantly smaller litter sizes. Ovaries from 4 weeks old Cnn2-KO mice showed significantly lower numbers of total ovarian follicles than WT control with the presence of multi-oocyte follicles. Cnn2-KO mice also showed age-progressive earlier depletion of ovarian follicles. Cnn2 expression is detected in the cumulus cells of the ovarian follicles of WT mice and colocalizes with actin stress fiber, tropomyosin and myosin II in primary cultures of cumulus cells.

CONCLUSIONS

The findings demonstrate that the loss of calponin 2 impairs ovarian folliculogenesis with premature depletion of ovarian follicles. The role of calponin 2 in ovarian granulosa cells suggests a molecular target for further investigations on the pathogenesis of POI and for therapeutic development.

A comprehensive review of human trophoblast fusion models: recent developments and challenges

As an essential component of the maternal-fetal interface, the placental syncytiotrophoblast layer contributes to a successful pregnancy by secreting hormones necessary for pregnancy, transporting nutrients, mediating gas exchange, balancing immune tolerance, and resisting pathogen infection. Notably, the deficiency in mononuclear trophoblast cells fusing into multinucleated syncytiotrophoblast has been linked to adverse pregnancy outcomes, such as preeclampsia, fetal growth restriction, preterm birth, and stillbirth. Despite the availability of many models for the study of trophoblast fusion, there exists a notable disparity from the ideal model, limiting the deeper exploration into the placental development. Here, we reviewed the existing models employed for the investigation of human trophoblast fusion from several aspects, including the development history, latest progress, advantages, disadvantages, scope of application, and challenges. The literature searched covers the monolayer cell lines, primary human trophoblast, placental explants, human trophoblast stem cells, human pluripotent stem cells, three-dimensional cell spheres, organoids, and placenta-on-a-chip from 1938 to 2023. These diverse models have significantly enhanced our comprehension of placental development regulation and the underlying mechanisms of placental-related disorders. Through this review, our objective is to provide readers with a thorough understanding of the existing trophoblast fusion models, making it easier to select most suitable models to address specific experimental requirements or scientific inquiries. Establishment and application of the existing human placental trophoblast fusion models.

Identification of methylation-regulated genes modulating microglial phagocytosis in hyperhomocysteinemia-exacerbated Alzheimer's disease

BACKGROUND

Hyperhomocysteinemia (HHcy) has been linked to development of Alzheimer's disease (AD) neuropathologically characterized by the accumulation of amyloid β (Aβ). Microglia (MG) play a crucial role in uptake of Aβ fibrils, and its dysfunction worsens AD. However, the effect of HHcy on MG Aβ phagocytosis remains unstudied.

METHODS

We isolated MG from the cerebrum of HHcy mice with genetic cystathionine-β-synthase deficiency (Cbs-/-) and performed bulk RNA-seq. We performed meta-analysis over transcriptomes of Cbs-/- mouse MG, human and mouse AD MG, MG Aβ phagocytosis model, human AD methylome, and GWAS AD genes.

RESULTS

HHcy and hypomethylation conditions were identified in Cbs-/- mice. Through Cbs-/- MG transcriptome analysis, 353 MG DEGs were identified. Phagosome formation and integrin signaling pathways were found suppressed in Cbs-/- MG. By analyzing MG transcriptomes from 4 AD patient and 7 mouse AD datasets, 409 human and 777 mouse AD MG DEGs were identified, of which 37 were found common in both species. Through further combinatory analysis with transcriptome from MG Aβ phagocytosis model, we identified 130 functional-validated Aβ phagocytic AD MG DEGs (20 in human AD, 110 in mouse AD), which reflected a compensatory activation of Aβ phagocytosis. Interestingly, we identified 14 human Aβ phagocytic AD MG DEGs which represented impaired MG Aβ phagocytosis in human AD. Finally, through a cascade of meta-analysis of transcriptome of AD MG, functional phagocytosis, HHcy MG, and human AD brain methylome dataset, we identified 5 HHcy-suppressed phagocytic AD MG DEGs (Flt1, Calponin 3, Igf1, Cacna2d4, and Celsr) which were reported to regulate MG/MΦ migration and Aβ phagocytosis.

CONCLUSIONS

We established molecular signatures for a compensatory response of Aβ phagocytosis activation in human and mouse AD MG and impaired Aβ phagocytosis in human AD MG. Our discoveries suggested that hypomethylation may modulate HHcy-suppressed MG Aβ phagocytosis in AD.

Proteomic Profiling of Extracellular Vesicles Isolated from Plasma and Peritoneal Exudate in Mice Induced by Crotalus scutulatus scutulatus Crude Venom and Its Purified Cysteine-Rich Secretory Protein (Css-CRiSP)

Increased vascular permeability is a frequent outcome of viperid snakebite envenomation, leading to local and systemic complications. We reported that snake venom cysteine-rich secretory proteins (svCRiSPs) from North American pit vipers increase vascular permeability both in vitro and in vivo. They also induce acute activation of several adhesion and signaling molecules that may play a critical role in the pathophysiology of snakebites. Extracellular vesicles (EVs) have gained interest for their diverse functions in intercellular communication, regulating cellular processes, blood-endothelium interactions, vascular permeability, and immune modulation. They also hold potential as valuable biomarkers for diagnosing, predicting, and monitoring therapeutic responses in different diseases. This study aimed to identify proteins in peritoneal exudate and plasma EVs isolated from BALB/c mice following a 30 min post-injection of Crotalus scutulatus scutulatus venom and its purified CRiSP (Css-CRiSP). EVs were isolated from these biofluids using the EVtrap method. Proteomic analysis of exudate- and plasma-derived EVs was performed using LC-MS/MS. We observed significant upregulation or downregulation of proteins involved in cell adhesion, cytoskeleton rearrangement, signal transduction, immune responses, and vesicle-mediated transports. These findings suggest that svCRiSPs play a crucial role in the acute effects of venom and contribute to the local and systemic toxicity of snakebites.

Evolution and function of calponin and transgelin

Calponin and transgelin (originally named SM22) are homologous cytoskeleton proteins that regulate actin-activated myosin motor functions in smooth muscle contraction and non-muscle cell motility during adhesion, migration, proliferation, phagocytosis, wound healing, and inflammatory responses. They are abundant cytoskeleton proteins present in multiple cell types whereas their physiological functions remain to be fully established. This focused review summarizes the evolution of genes encoding calponin and transgelin and their isoforms and discusses the structural similarity and divergence in vertebrate and invertebrate species in the context of functions in regulating cell motility. As the first literature review focusing on the evolution of the calponin-transgelin family of proteins in relevance to their structure-function relationship, the goal is to outline a foundation of current knowledge for continued investigations to understand the biological functions of calponin and transgelin in various cell types during physiological and pathological processes.

Promoting effects of calponin 3 on the growth of diffuse large B‑cell lymphoma cells

Diffuse large B‑cell lymphoma (DLBCL) is one of the most common types of lymphoma. Calponin 3 (CNN3) is a thin filament‑associated protein previously known to regulate smooth muscle contraction. Recent evidence illustrates its involvement in carcinogenesis; however, its roles in DLBCL remain unknown. CNN3 was found to be highly expressed in DLBCL specimens according to the online Gene Expression Profiling Interactive Analysis data. The aim of the present study was to investigate the roles of CNN3 in the progression of DLBCL. In vitro, the ectopic expression of CNN3 promoted the proliferation and G1/S transition of DLBCL cells, while its silencing led to opposite alterations. A similar tumor‑promoting role of CNN3 was also demonstrated by injecting nude mice with DLBCL cells over‑ or underexpressing CNN3. The results of dual‑luciferase reporter and chromatin immunoprecipitation assays revealed that forkhead box O3 (FOXO3), a known tumor suppressor in DLBCL, bound to the CNN3 promoter at ‑1955/‑1948 and ‑1190/‑1183, and suppressed the transcription of CNN3. The alterations induced by FOXO3 were partly blocked by CNN3 overexpression. On the whole, the present study demonstrates that CNN3, whose transcriptional activity is negatively regulated by FOXO3, contributes to the malignant behavior of DLBCL cells. The findings of the present study may provide novel diagnostic or therapeutic insight for DLBCL in clinical practice.

Loss of Calponin 2 causes age-progressive proteinuria in mice

Proteinuria is a major manifestation of kidney disease, reflecting injuries of glomerular podocytes. Actin cytoskeleton plays a pivotal role in stabilizing the foot processes of podocytes against the hydrostatic pressure of filtration. Calponin is an actin associated protein that regulates mechanical tension-related cytoskeleton functions and its role in podocytes has not been established. Here we studied the kidney phenotypes of calponin isoform 2 knockout (KO) mice. Urine samples were examined to quantify the ratio of albumin and creatinine. Kidney tissue samples were collected for histology and ultrastructural studies. A mouse podocyte cell line (E11) was used to study the expression and cellular localization of calponin 2. In comparison with wild-type (WT) controls, calponin 2 KO mice showed age-progressive high proteinuria and degeneration of renal glomeruli. High levels of calponin 2 are expressed in E11 podocytes and colocalized with actin stress fibers, tropomyosin and myosin IIA. Electron microscopy showed that aging calponin 2 KO mice had effacement of the podocyte foot processes and increased thickness of the glomerular basement membrane as compared to that of WT control. The findings demonstrate that deletion of calponin 2 aggravates age-progressive degeneration of the glomerular structure and function as filtration barrier. The critical role of calponin 2 in podocytes suggests a molecular target for understanding the pathogenesis of proteinuria and therapeutic development.

How trophoblasts fuse: an in-depth look into placental syncytiotrophoblast formation

In humans, cell fusion is restricted to only a few cell types under normal conditions. In the placenta, cell fusion is a critical process for generating syncytiotrophoblast: the giant multinucleated trophoblast lineage containing billions of nuclei within an interconnected cytoplasm that forms the primary interface separating maternal blood from fetal tissue. The unique morphology of syncytiotrophoblast ensures that nutrients and gases can be efficiently transferred between maternal and fetal tissue while simultaneously restricting entry of potentially damaging substances and maternal immune cells through intercellular junctions. To maintain integrity of the syncytiotrophoblast layer, underlying cytotrophoblast progenitor cells terminate their capability for self-renewal, upregulate expression of genes needed for differentiation, and then fuse into the overlying syncytium. These processes are disrupted in a variety of obstetric complications, underscoring the importance of proper syncytiotrophoblast formation for pregnancy health. Herein, an overview of key mechanisms underlying human trophoblast fusion and syncytiotrophoblast development is discussed.

Deletion of Calponin 2 Reduces the Formation of Postoperative Peritoneal Adhesions

Aim of the study: Postoperative peritoneal adhesions are a common cause of morbidity after surgery, resulting in multiple complications. Macrophage-mediated inflammation and myofibroblast differentiation after tissue injury play central roles in the pathogenesis and progression of adhesion formation. Calponin 2 is an actin cytoskeleton regulatory protein in endothelial cells, macrophages and fibroblasts that are key players in the development of fibrosis. Deletion of calponin 2 has been shown to attenuate inflammatory arthritis, atherosclerosis and fibrocalcification of the aortic valves. The present study investigated the effect of calponin 2 deletion on attenuating the formation of peritoneal adhesions in a mouse model for potential use as a new therapeutic target.Materials and methods: Sterile surgical procedures under general anesthesia were used on paired wild type (WT) and calponin 2 knockout (KO) mice to generate mild injury on the cecal and abdominal wall peritonea. Three and seven days post-operation, the mice were compared postmortem for the formation of peritoneal adhesions. Tissues at the adhesion sites were examined with histology and immunofluorescent studies for macrophage and myofibroblast activations.Results: Quantitative scoring demonstrated that calponin 2 KO mice developed significantly less postoperative peritoneal adhesions than that in WT mice. Calponin 2 deletion resulted in less infiltration of F4/80⁺ macrophages at the adhesion sites with less myofibroblast differentiation and collagen deposition than WT controls.Conclusions: The data show that deletion of calponin 2 effectively reduces postoperative peritoneal adhesion, presenting a novel molecular target for clinical prevention.

FURIN correlated with immune infiltration serves as a potential biomarker in SARS-CoV-2 infection-related lung adenocarcinoma

FURIN, as a proprotein convertase, has been found to be expressed in a variety of cancers and plays an important role in cancer. In addition, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires FURIN to enter human cells. However, the role of FURIN in lung adenocarcinoma remains unclear. And the expression of SARS-CoV-2 related gene in lung adenocarcinoma has not been clarified. Therefore, in order to explore the prognostic value and mechanism of FURIN in lung adenocarcinoma, we performed bioinformatics analysis with Oncomine, Tumor Immune Estimation Resource, Gene Expression Profiling Interactive Analysis, human protein atlas, UALCAN, PrognoScan, Kaplan–Meier plotter, cBioPortal and LinkedOmics databases. And then we used GSE44274 in the GEO (Gene Expression Omnibus) database to analyze the expression of FURIN in LUAD patients who infected with SARS-CoV. FURIN was highly expressed in lung adenocarcinoma and was significantly associated with poor overall survival. FURIN expression was found to be correlated with six major permeable immune cells and with macrophage immune marker in LUAD patients. In addition, SARS-CoV-2 infection might affect the expression of FURIN. FURIN can be used as a promising biomarker for determining prognosis and immune infiltration in LUAD patients.

Knockdown of CNN3 Impairs Myoblast Proliferation, Differentiation, and Protein Synthesis via the mTOR Pathway

Background

Myogenesis is a complex process that requires optimal outside–in substrate–cell signaling. Calponin 3 (CNN3) plays an important role in regulating myogenic differentiation and muscle regeneration; however, the precise function of CNN3 in myogenesis regulation remains poorly understood. Here, we investigated the role of CNN3 in a knockdown model in the mouse muscle cell line C2C12.

Methods

Myoblast proliferation, migration, differentiation, fusion, and protein synthesis were examined in CNN3 knockdown C2C12 mouse muscle cells. Involvement of the mTOR pathway in CNN3 signaling was explored by treating cells with the mTOR activator MHY1485. The regulatory mechanisms of CNN3 in myogenesis were further examined by RNA sequencing and subsequent gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and gene set enrichment analysis (GSEA).

Results

During proliferation, CNN3 knockdown caused a decrease in cell proliferation and migration. During differentiation, CNN3 knockdown inhibited myogenic differentiation, fusion, and protein synthesis in C2C12 cells via the AKT/mTOR and AMPK/mTOR pathways; this effect was reversed by MHY1485 treatment. Finally, KEGG and GSEA indicated that the NOD-like receptor signaling pathway is affected in CNN3 knockdown cell lines.

Conclusion

CNN3 may promote C2C12 cell growth by regulating AKT/mTOR and AMPK/mTOR signaling. The KEGG and GSEA indicated that inhibiting CNN3 may activate several pathways, including the NOD-like receptor pathway and pathways involved in necroptosis, apoptosis, and inflammation.

Differential Membrane Protein Profile in Bovine X- and Y-Sperm

The aim of this study was to understand the molecular mechanisms behind the biological differences of X- and Y-sperm and to screen the sex-specific candidate antigen proteins for sexed semen production. To this end, we investigated differential expression of total membrane proteins of the two sperm types by using high-purity X- and Y-sperm from 20 Holstein bulls and applying the label-free proteomic technique; 1521 proteins were identified. In the X-sperm group, 8 and 23 proteins were significantly up- and down-regulated, respectively. In the X- and the Y-sperm group, 151 and 88 proteins were specifically expressed, respectively. These were overexpressed in the dynamic changes of the actin cytoskeleton, and cell senescence/apoptosis induced by the immune response, and could result in differences in the state, size, and immune sensitivity of the X-/Y-sperm membranes. The prediction of transmembrane structure, subcellular localization, and Western blotting validation results showed that the CLRN3 and SCAMP1 proteins were cell surface specific antigens of X- and Y-sperm, respectively. Our findings help explain the molecular mechanism behind the biological differences of X-/Y-sperm and lay the foundation for application of immunological methods to produce sex-sorted semen and control livestock sex. Data are available via ProteomeXchange with identifier PXD019435.

Serum Calponin 3 Levels in Patients with Systemic Sclerosis: Possible Association with Skin Sclerosis and Arthralgia

Systemic sclerosis (SSc) is a connective tissue disease characterized by tissue fibrosis and vasculopathy in various organs with a background of inflammation initiated by autoimmune abnormalities. Calponin 3 plays a role in the cell motility and contractibility of fibroblasts during wound healing in the skin. We aimed to evaluate serum calponin 3 levels in SSc patients and their association with clinical manifestations of SSc. Serum samples were collected from 68 patients with SSc and 20 healthy controls. Serum calponin 3 levels were examined using enzyme-linked immunosorbent assay kits, and their association with clinical features of SSc was statistically analyzed. The upper limit of the 95% confidence interval of serum calponin 3 levels in healthy controls was utilized as the cut-off value when dividing SSc patients into the elevated and normal groups. Serum calponin 3 levels were significantly higher in SSc patients than in healthy controls (mean (95% confidence interval), 15.38 (14.66–16.11) vs. 13.56 (12.75–14.38) ng/mL, p < 0.05). The modified Rodnan total skin thickness score was significantly higher in the elevated serum calponin 3 level group than in the normal level group (median (25–75th percentiles), 10.0 (2.0–16.0) vs. 6.5 (3.25–8.75), p < 0.05). Moreover, SSc patients with increased serum calponin 3 levels also had a higher frequency of arthralgia (40% vs. 9%, p < 0.05). Elevated serum calponin 3 levels were associated with skin sclerosis and arthralgia in SSc patients. Serum calponin 3 levels might be a biomarker that reflects the severity of skin sclerosis and joint involvement in SSc.

Stable Epigenetic Programming of Effector and Central Memory CD4 T Cells Occurs Within 7 Days of Antigen Exposure In Vivo

T cell immunological memory is established within days of an infection, but little is known about the in vivo changes in gene regulatory networks accounting for their ability to respond more efficiently to secondary infections. To decipher the timing and nature of immunological memory we performed genome-wide analyses of epigenetic and transcriptional changes in a mouse model generating antigen-specific T cells. Epigenetic reprogramming for Th differentiation and memory T cell formation was already established by the peak of the T cell response after 7 days. The Th memory T cell program was associated with a gain of open chromatin regions, enriched for RUNX, ETS and T-bet motifs, which remained stable for 56 days. The epigenetic programs for both effector memory, associated with T-bet, and central memory, associated with TCF-1, were established in parallel. Memory T cell-specific regulatory elements were associated with greatly enhanced inducible Th1-biased responses during secondary exposures to antigen. Furthermore, memory T cells responded in vivo to re-exposure to antigen by rapidly reprograming the entire ETS factor gene regulatory network, by suppressing Ets1 and activating Etv6 expression. These data show that gene regulatory networks are epigenetically reprogrammed towards memory during infection, and undergo substantial changes upon re-stimulation.

circRNA CDR1as Promotes Pulmonary Artery Smooth Muscle Cell Calcification by Upregulating CAMK2D and CNN3 via Sponging miR-7-5p

Emerging evidence has suggested that circular RNAs (circRNAs) are involved in multiple physiological processes and participate in a variety of human diseases. However, the underlying biological function of circRNAs in pulmonary hypertension (PH) is still ambiguous. Herein, we investigated the implication and regulatory effect of a typical circRNA, CDR1as, in the pathological process of vascular calcification in PH. Human pulmonary artery smooth muscle cell (HPASMC) calcification was analyzed by western blotting, immunofluorescence, alizarin red S staining, alkaline phosphatase activity analysis, and calcium deposition quantification. CDR1as targets were identified by bioinformatics analysis and validated by dual-luciferase reporter and RNA antisense purification assays. We identified that CDR1as was upregulated in hypoxic conditions and promoted a phenotypic switch of HPASMCs from a contractile to an osteogenic phenotype. Moreover, microRNA (miR)-7-5p was shown to be a target of CDR1as, and calcium/calmodulin-dependent kinase II-delta (CAMK2D) and calponin 3 (CNN3) were suggested to be the putative target genes and regulated by CDR1as/miR-7-5p. The results showed that the CDR1as/miR-7-5p/CNN3 and CAMK2D regulatory axis mediates HPASMC osteoblastic differentiation and calcification induced by hypoxia. This evidence reveals an approach to the treatment of PH.

Calponin 3 is associated with poor prognosis and regulates proliferation and metastasis in osteosarcoma

Osteosarcoma is a malignant, life-threatening tumor that affects children and adolescents. In this study, we identified high levels of calponin 3 (CNN3) protein in osteosarcoma tissues and cell lines. The receiver operating characteristic curve analysis revealed that CNN3 has diagnostic value for patients with osteosarcoma. We also found that high CNN3 expression was associated with tumor size, tumor stage, and lymph node and distant metastases. Moreover, high levels of CNN3 mRNA were associated with a poor overall survival rate and a shorter disease-free survival period. CNN3 silencing inhibited cell proliferation, induced apoptosis and cell cycle arrest at the G1 stage, and inhibited cell migration and invasion in vitro. Furthermore, CNN3 silencing also inhibited subcutaneous tumor growth and lung metastasis in vivo. Western blotting revealed that silencing of CNN3 resulted in downregulated expression of MMP9, VEGF, and vimentin, and upregulation of E-cadherin. CNN3 silencing also resulted in downregulation of the ERK1/2 and p38 signaling pathways. In conclusion, high CNN3 expression was found to help in the diagnosis of osteosarcoma, and was found to be associated with poor prognosis in patients. Therefore, CNN3 may play an oncogenic role during the progression of osteosarcoma by activating the ERK1/2 and p38 pathways.

Spitzenkörper assembly mechanisms reveal conserved features of fungal and metazoan polarity scaffolds

The Spitzenkörper (SPK) constitutes a collection of secretory vesicles and polarity-related proteins intimately associated with polarized growth of fungal hyphae. Many SPK-localized proteins are known, but their assembly and dynamics remain poorly understood. Here, we identify protein-protein interaction cascades leading to assembly of two SPK scaffolds and recruitment of diverse effectors in Neurospora crassa. Both scaffolds are transported to the SPK by the myosin V motor (MYO-5), with the coiled-coil protein SPZ-1 acting as cargo adaptor. Neither scaffold appears to be required for accumulation of SPK secretory vesicles. One scaffold consists of Leashin-2 (LAH-2), which is required for SPK localization of the signalling kinase COT-1 and the glycolysis enzyme GPI-1. The other scaffold comprises a complex of Janus-1 (JNS-1) and the polarisome protein SPA-2. Via its Spa homology domain (SHD), SPA-2 recruits a calponin domain-containing F-actin effector (CCP-1). The SHD NMR structure reveals a conserved surface groove required for effector binding. Similarities between SPA-2/JNS-1 and the metazoan GIT/PIX complex identify foundational features of the cell polarity apparatus that predate the fungal-metazoan divergence.

The Spitzenkörper (SPK) is a polarized accumulation of proteins and secretory vesicles associated with tip growth of fungal hyphae. Here, Zheng et al. study SPK assembly and dynamics, identify SPK protein scaffolds and associated proteins, and reveal similarities with other scaffolds from metazoans.

Mechanobiological regulation of placental trophoblast fusion and function through extracellular matrix rigidity

The syncytiotrophoblast is a multinucleated layer that plays a critical role in regulating functions of the human placenta during pregnancy. Maintaining the syncytiotrophoblast layer relies on ongoing fusion of mononuclear cytotrophoblasts throughout pregnancy, and errors in this fusion process are associated with complications such as preeclampsia. While biochemical factors are known to drive fusion, the role of disease-specific extracellular biophysical cues remains undefined. Since substrate mechanics play a crucial role in several diseases, and preeclampsia is associated with placental stiffening, we hypothesize that trophoblast fusion is mechanically regulated by substrate stiffness. We developed stiffness-tunable polyacrylamide substrate formulations that match the linear elasticity of placental tissue in normal and disease conditions, and evaluated trophoblast morphology, fusion, and function on these surfaces. Our results demonstrate that morphology, fusion, and hormone release is mechanically-regulated via myosin-II; optimal on substrates that match healthy placental tissue stiffness; and dysregulated on disease-like and supraphysiologically-stiff substrates. We further demonstrate that stiff regions in heterogeneous substrates provide dominant physical cues that inhibit fusion, suggesting that even focal tissue stiffening limits widespread trophoblast fusion and tissue function. These results confirm that mechanical microenvironmental cues influence fusion in the placenta, provide critical information needed to engineer better in vitro models for placental disease, and may ultimately be used to develop novel mechanically-mediated therapeutic strategies to resolve fusion-related disorders during pregnancy.

The Absence of Calponin 2 in Rabbits Suggests Caution in Choosing Animal Models

While the rapid development of CRISPR/CAS9 technology has allowed for readily performing site-specific genomic editing in non-rodent species, an emerging challenge is to select the most suitable species to generate animal models for the study of human biology and diseases. Improving CRISPR/CAS9 methodology for more effective and precise editing in the rabbit genome to replicate human disease is an active area of biomedical research. Although rabbits are more closely related to humans than mice (based on DNA sequence analysis), our whole-genome protein database search revealed that rabbits have more missing human protein sequences than mice. Hence, precisely replicating human diseases in rabbits requires further consideration, especially in studies involving essential functions of the missing proteins. For example, rabbits lack calponin 2, an actin-associated cytoskeletal protein that is important in the pathogenesis of inflammatory arthritis, atherosclerosis, and calcific aortic valve disease. The justification of using rabbits as models for human biomedical research is based on their larger size and their closer phylogenetic distance to humans (based on sequence similarity of conserved genes), but this may be misleading. Our findings, which consider whole-genome protein profiling together with actual protein expressions, serve as a warning to the scientific community to consider overall conservation as well as the conservation of specific proteins when choosing an animal model to study a particular aspect of human biology prior to investing in genetic engineering.

CNN3 acts as a potential oncogene in cervical cancer by affecting RPLP1 mRNA expression

The prognosis of advanced stage cervical cancer is poorer due to cancer invasion and metastasis. Exploring new factors and signalling pathways associated with invasiveness and metastasis would help to identify new therapeutic targets for advanced cervical cancer. We searched the cancer microarray database, Oncomine, and found elevated calponin 3 (CNN3) mRNA expression in cervical cancer tissues. QRT-PCR verified the increased CNN3 expression in cervical cancer compared to para-cancer tissues. Proliferation, migration and invasion assays showed that overexpressed CNN3 promoted the viability and motility of cervical cancer cells, the opposite was observed in CNN3-knockdown cells. In addition, xenografted tumours, established from SiHa cells with CNN3 knockdown, displayed decreased growth and metastasis in vivo. Furthermore, RNA-sequencing showed that ribosomal protein lateral stalk subunit P1 (RPLP1) was a potential downstream gene. Gene function experiments revealed that RPLP1 had the same biological effects as CNN3 did. Rescue experiments demonstrated that the phenotypes inhibited by CNN3 silencing were partly or completely reversed by RPLP1 overexpression. In conclusion, we verified that CNN3 acts as an oncogene to promote the viability and motility of cervical cancer cells in vitro and accelerate the growth and metastasis of xenografted tumours in vivo, by affecting RPLP1 expression.

Down-regulation of endothelial protein C receptor promotes preeclampsia by affecting actin polymerization

Preeclampsia is a severe pregnancy-related disease that is found in 3%-5% of pregnancies worldwide and is primarily related to the decreased proliferation and invasion of trophoblast cells and abnormal uterine spiral artery remodelling. However, studies on the pathogenesis of placental trophoblasts are insufficient, and the aetiology of PE remains unclear. Here, we report that endothelial protein C receptor (EPCR), a transmembrane glycoprotein, was down-regulated in placentas from preeclamptic patients. Moreover, lack of EPCR significantly reduced the trophoblast cell proliferation, invasion and tube formation capabilities. Microscale thermophoresis analysis showed that EPCR directly bound to protease-activated receptor 1 (PAR-1), a G protein-coupled receptor. This change resulted in a substantial reduction in active Rac1 and caused excessive actin rearrangement. Our findings reveal a previously unidentified role of EPCR in the regulation of trophoblast proliferation, invasion and tube formation through promotion of actin polymerization, which is required for normal placental development.

Calponin-3 deficiency augments contractile activity, plasticity, fibrogenic response and Yap/Taz transcriptional activation in lens epithelial cells and explants

The transparent ocular lens plays a crucial role in vision by focusing light on to the retina with loss of lens transparency leading to impairment of vision. While maintenance of epithelial phenotype is recognized to be essential for lens development and function, knowledge of the identity of different molecular mechanisms regulating lens epithelial characteristics remains incomplete. This study reports that CNN-3, the acidic isoform of calponin, an actin binding contractile protein, is expressed preferentially and abundantly relative to the basic and neutral isoforms of calponin in the ocular lens, and distributes predominantly to the epithelium in both mouse and human lenses. Expression and MEKK1-mediated threonine 288 phosphorylation of CNN-3 is induced by extracellular cues including TGF-β2 and lysophosphatidic acid. Importantly, siRNA-induced deficiency of CNN3 in lens epithelial cell cultures and explants results in actin stress fiber reorganization, stimulation of focal adhesion formation, Yap activation, increases in the levels of α-smooth muscle actin, connective tissue growth factor and fibronectin, and decreases in E-cadherin expression. These results reveal that CNN3 plays a crucial role in regulating lens epithelial contractile activity and provide supporting evidence that CNN-3 deficiency is associated with the induction of epithelial plasticity, fibrogenic activity and mechanosensitive Yap/Taz transcriptional activation.

miR-106b-5p contributes to the lung metastasis of breast cancer via targeting CNN1 and regulating Rho/ROCK1 pathway

OBJECTIVES

Breast cancer has been the second most prevalent and fatal malignancy due to its frequent metastasis to other organs. We aim to study the effects of a key miRNA-mRNA signaling in breast cancer.

RESULTS

CNN1 was identified as the key gene in breast cancer by the bioinformatics analysis, and the downregulation of CNN1 in breast cancer tissues and cell lines was observed. Upregulating CNN1 inhibited cell survival, migration, invasion, and adhesion, but enhanced cell apoptosis. miR-106b-5p not only bound to CNN1 mRNA 3'UTR, but also promoted lung metastasis in vivo. Besides, the miR-106b-5p mimic enhanced breast cancer canceration by targeting CNN1 and activating Rho/ROCK1 signaling pathway.

CONCLUSION

Overall, our results proved that miR-106b-5p promoted the metastasis of breast cancer by suppressing CNN1 and activating Rho/ROCK1 pathway.

METHODS

Bioinformatics analysis was performed to select the key gene in breast cancer. The overexpression and knockdown of Calponin 1 (CNN1) in breast cancer cell lines were performed to conduct cell viability, migrating, invasion, proliferation, adhesion, and apoptosis experiments. To identify the role of miR-106b-5p and Rho/ROCK1 in CNN1-induced breast cancer, a dual-luciferase assay, tumor lung metastasis assay, transcript half-life assay, and Rho/ROCK1 inhibition assay were performed.

Biomimetic Micropatterned Adhesive Surfaces To Mechanobiologically Regulate Placental Trophoblast Fusion

The placental syncytiotrophoblast is a giant multinucleated cell that forms a tree-like structure and regulates transport between mother and baby during development. It is maintained throughout pregnancy by continuous fusion of trophoblast cells, and disruptions in fusion are associated with considerable adverse health effects including diseases such as preeclampsia. Developing predictive control over cell fusion in culture models is hence of critical importance in placental drug discovery and transport studies, but this can currently be only partially achieved with biochemical factors. Here, we investigate whether biophysical signals associated with budding morphogenesis during development of the placental villous tree can synergistically direct and enhance trophoblast fusion. We use micropatterning techniques to manipulate physical stresses in engineered microtissues and demonstrate that biomimetic geometries simulating budding robustly enhance fusion and alter spatial patterns of synthesis of pregnancy-related hormones. These findings indicate that biophysical signals play a previously unrecognized and significant role in regulating placental fusion and function, in synergy with established soluble signals. More broadly, our studies demonstrate that biomimetic strategies focusing on tissue mechanics can be important approaches to design, build, and test placental tissue cultures for future studies of pregnancy-related drug safety, efficacy, and discovery.

Downregulation of calponin 2 contributes to the quiescence of lung macrophages

Calponin 2 is an actin cytoskeleton-associated regulatory protein that inhibits the activity of myosin-ATPase and cytoskeleton dynamics. Recent studies have demonstrated that deletion of calponin 2 restricts the proinflammatory activation of macrophages in atherosclerosis and arthritis to attenuate the disease progression in mice. Here we demonstrate that the levels of calponin 2 vary among different macrophage populations, which may reflect their adaptation to specific tissue microenvironment corresponding to specific functional states. Interestingly, lung resident macrophages express significantly lower calponin 2 than peritoneal resident macrophages, which correlates with decreased substrate adhesion and reduced expression of proinflammatory cytokines and a proresolution phenotype. Deletion of calponin 2 in peritoneal macrophages also decreased substrate adhesion and downregulated the expression of proinflammatory cytokines. Providing the first line of defense against microbial invasion while receiving constant exposure to extrinsic antigens, lung macrophages need to maintain a necessary level of activity while limiting exaggerated inflammatory reaction. Therefore, their low level of calponin 2 may reflect an important physiological adaption. Downregulation of calponin 2 in macrophages may be targeted as a cytoskeleton-based novel mechanism, possibly via endoplasmic reticulum stress altering the processing and secretion of cytokines, to regulate immune response and promote quiescence for the treatment of inflammatory diseases.

Establishment of a novel experimental model for muscle-invasive bladder cancer using a dog bladder cancer organoid culture

In human and dogs, bladder cancer (BC) is the most common neoplasm affecting the urinary tract. Dog BC resembles human muscle‐invasive BC in histopathological characteristics and gene expression profiles, and could be an important research model for this disease. Cancer patient‐derived organoid culture can recapitulate organ structures and maintains the gene expression profiles of original tumor tissues. In a previous study, we generated dog prostate cancer organoids using urine samples, however dog BC organoids had never been produced. Therefore we aimed to generate dog BC organoids using urine samples and check their histopathological characteristics, drug sensitivity, and gene expression profiles. Organoids from individual BC dogs were successfully generated, expressed urothelial cell markers (CK7, CK20, and UPK3A) and exhibited tumorigenesis in vivo. In a cell viability assay, the response to combined treatment with a range of anticancer drugs (cisplatin, vinblastine, gemcitabine or piroxicam) was markedly different in each BC organoid. In RNA‐sequencing analysis, expression levels of basal cell markers (CK5 and DSG3) and several novel genes (MMP28,CTSE,CNN3,TFPI2,COL17A1, and AGPAT4) were upregulated in BC organoids compared with normal bladder tissues or two‐dimensional (2D) BC cell lines. These established dog BC organoids might be a useful tool, not only to determine suitable chemotherapy for BC diseased dogs but also to identify novel biomarkers in human muscle‐invasive BC. In the present study, for the 1st time, dog BC organoids were generated and several specifically upregulated organoid genes were identified. Our data suggest that dog BC organoids might become a new tool to provide fresh insights into both dog BC therapy and diagnostic biomarkers.

MiR-17 and miR-19 cooperatively promote skeletal muscle cell differentiation

Skeletal myogenesis is a highly coordinated process that involves cell proliferation, differentiation and fusion controlled by a complex gene regulatory network. The microRNA gene cluster miR-17–92 has been shown to be related to this process; however, the exact role of each cluster member remains unclear. Here, we show that miR-17 and miR-20a could effectively promote the differentiation of both C2C12 myoblasts and primary bovine satellite cells. In contrast, miR-18a might play a negative role in C2C12 cell differentiation, while miR-19 and miR-92a had little influence. Transcriptome and target analyses revealed that miR-17 could act on Ccnd2, Jak1 and Rhoc genes that are critical for cell proliferation and/or fusion. Notably, the addition of miR-19 could reverse the lethal effect of miR-17 and could thus facilitate the maturation of myotubes. Furthermore, by co-injecting the lentiviral shRNAs of miR-17 and miR-19 into mouse tibialis anterior muscles, we demonstrated the wound healing abilities of the two miRNAs. Our findings indicate that in combination with miR-19, miR-17 is a potent inducer of skeletal muscle differentiation.

Trophoblastic proliferation and invasion regulated by ACTN4 is impaired in early onset preeclampsia

Successful pregnancy requires normal placentation, which largely depends on the tight regulation of proliferation, invasion, and migration of trophoblast cells. Abnormal functioning of trophoblast cells may cause failure of uterine spiral artery remodeling, which may be related to pregnancy-related disorders, such as preeclampsia. Here, we reported that an actin-binding protein, α-actinin (ACTN)4, was dysregulated in placentas from early onset preeclampsia. Moreover, knockdown of ACTN4 markedly inhibited trophoblast cell proliferation by reducing AKT membrane translocation. Furthermore, E-cadherin regulated ACTN4 and β-catenin colocalization on trophoblast cell podosomes, and ACTN4 down-regulation suppressed the E-cadherin-induced cell invasion increase via depolymerizing actin filaments. Moreover, loss of ACTN4 recapitulated a number of the features of human preeclampsia. Therefore, our data indicate that ACNT4 plays a role in trophoblast function and is required for normal placental development.-Peng, W., Tong, C., Li, L., Huang, C., Ran, Y., Chen, X., Bai, Y., Liu, Y., Zhao, J., Tan, B., Luo, X., Wang, H., Wen, L., Zhang, C., Zhang, H., Ding, Y., Qi, H., Baker, P. N. Trophoblastic proliferation and invasion regulated by ACTN4 is impaired in early onset preeclampsia.

An in vivo RNAi mini-screen in Drosophila cancer models reveals novel potential Wnt targets in liver cancer

BACKGROUND/AIMS

Aberrant activation of the Wnt/β-catenin signaling, which arises from the accumulation of mutant β-catenin in the cell, is one of the most common driving forces in hepatocellular carcinoma (HCC). We previously identified several genes that are regulated on the overexpression of β-catenin in the HCC cell line that are suggested to be novel Wnt/β-catenin targets playing effective roles in cancer. The aim of the present study was to elucidate the roles of these putative target genes in tumorigenesis with an in vivo analysis in Drosophila.

MATERIALS AND METHODS

We selected 15 genes downregulated in two Drosophila cancer models.

RESULTS

The results from the RNAi mini-screen revealed novel roles for the analyzed putative Wnt/β-catenin target genes in tumorigenesis. The downregulation of the analyzed nine genes led to tumor formation as well as metastasis in Drosophila, suggesting a tumor suppressor function. On the other hand, the knockdown of the other two genes suppressed tumor and metastasis formations and disturbed the development of the analyzed eye tissues, indicating an oncogenic or developmental role for these genes.

CONCLUSION

These findings could serve to identify novel subjects for cancer research in order to provide insight into the diagnostic and therapeutic processes of several cancer types.

Tumor suppressor miR-1 inhibits tumor growth and metastasis by simultaneously targeting multiple genes

Cancer progression depends on tumor growth and metastasis, which are activated or suppressed by multiple genes. An individual microRNA may target multiple genes, suggesting that a miRNA may suppress tumor growth and metastasis via simultaneously targeting different genes. However, thus far, this issue has not been explored. In the present study, the findings showed that miR-1 could simultaneously inhibit tumor growth and metastasis of gastric and breast cancers by targeting multiple genes. The results indicated that miR-1 was significantly downregulated in cancer tissues compared with normal tissues. The miR-1 overexpression led to cell cycle arrest in the G1 phase in gastric and breast cancer cells but not in normal cells. Furthermore, the miR-1 overexpression significantly inhibited the metastasis of gastric and breast cancer cells. An analysis of the underlying mechanism revealed that the simultaneous inhibition of tumor growth and metastasis mediated by miR-1 was due to the synchronous targeting of 6 miR-1 target genes encoding cyclin dependent kinase 4, twinfilin actin binding protein 1, calponin 3, coronin 1C, WAS protein family member 2 and thymosin beta 4, X-linked. In vivo assays demonstrated that miR-1 efficiently inhibited tumor growth and metastasis of gastric and breast cancers in nude mice. Therefore, our study contributed novel insights into the miR-1′s roles in tumorigenesis of gastric and breast cancers.

Multiple bioanalytical method to reveal developmental biological responses in zebrafish embryos exposed to triclocarban

Triclocarban (TCC) is a well-known antibacterial agent that is frequently detected in environmental, wildlife and human samples. The potential toxicological effects and action mechanism of TCC on vertebrate development has remained unclear. In the present study, we analyzed phenotypic alterations, thyroid hormone levels, thyroid hormone responsive genes, and proteomic profiles of zebrafish embryos after exposure to a series of concentrations of TCC from 6 h post-fertilization (hpf) to 120 hpf. The most nonlethal concentration (MNLC), lethal concentration 10% (LC₁₀) and lethal concentration 50% (LC₅₀) of TCC for exposures of 96 h were 133.3 μg/L, 147.5 μg/L and 215.8 μg/L, respectively. Our results showed that exposure to TCC decreased heart rate, delayed yolk absorption and swim bladder development at MNLC and LC₁₀. Exposure to MNLC of TCC inhibited thyroid hormone and altered expression of thyroid hormone responsive genes. Furthermore, exposure to 1/20 MNLC of TCC altered expression of proteins related to binding and metabolism, skeletal muscle development and function, as well as proteins involved in nervous system development and immune response, indicating TCC has potential health risks in wildlife and humans at low concentration level.

The hallmarks of cell-cell fusion

Cell-cell fusion is essential for fertilization and organ development. Dedicated proteins known as fusogens are responsible for mediating membrane fusion. However, until recently, these proteins either remained unidentified or were poorly understood at the mechanistic level. Here, we review how fusogens surmount multiple energy barriers to mediate cell-cell fusion. We describe how early preparatory steps bring membranes to a distance of ∼10 nm, while fusogens act in the final approach between membranes. The mechanical force exerted by cell fusogens and the accompanying lipidic rearrangements constitute the hallmarks of cell-cell fusion. Finally, we discuss the relationship between viral and eukaryotic fusogens, highlight a classification scheme regrouping a superfamily of fusogens called Fusexins, and propose new questions and avenues of enquiry.

Cnn3 regulates neural tube morphogenesis and neuronal stem cell properties

Calponin 3 (Cnn3) is a member of the Cnn family of actin-binding molecules that is highly expressed in the mammalian brain and has been shown to control dendritic spine morphology, density, and plasticity by regulating actin cytoskeletal reorganization and dynamics. However, little is known about the role of Cnn3 during embryonic development. In this study, we analyzed mutant animals deficient in Cnn3 to gain a better understanding of its role in brain morphogenesis. Embryos lacking Cnn3 exhibited massive malformation of the developing brain including exoencephaly, closure defects at the rostral neural tube, and strong enlargement of brain tissue. In wild-type animals, we found Cnn3 being localized to the apical lining of the neuroepithelium in close vicinity to beta-Catenin and N-cadherin. By performing immunohistochemistry on beta-Catenin and p-Smad, and furthermore taking advantage of Wnt-reporter animals, we provide evidence that the loss of Cnn3 during development can affect signaling pathways crucial for correct morphogenesis of the neural tube. In addition, we used embryonic neurosphere cultures to investigate the role of Cnn3 in embryonic neuronal stem cells (NSC). Here, we observed that Cnn3 deficiency in NSCs increased the number of newly formed neurospheres and increased neurosphere size without perturbing their differentiation potential. Together, our study provides evidence for an important role of Cnn3 during development of the embryonic brain and in regulating NSC function.

Mechanoregulation of SM22α/Transgelin

SM22α, also named transgelin, is an actin filament-associated protein in smooth muscle and fibroblasts. Three decades after its discovery, the biological function of SM22α remains under investigation. Here we report a novel finding that the expression and degradation of SM22α/transgelin are regulated by mechanical tension. Following a mass spectrometry identification of SM22α degradation in isolated and tension-unloaded mouse aorta, we developed specific monoclonal antibodies to study the regulation of SM22α in human fetal lung myofibroblast line MRC-5 and primary cultures of neonatal mouse skin fibroblasts. The level of SM22α is positively related to the mechanical tension in the cytoskeleton produced by the myosin II motor in response to the stiffness of the culture matrix. Quantitative reverse transcription polymerase chain reaction demonstrated that the expression of SM22α is regulated at the transcriptional level. This mechanical regulation resembles that of calponin 2, another actin filament-associated protein. Immunofluorescent staining co-localized SM22α with F-actin, myosin, and calponin 2 in mouse skin fibroblasts. The close phylogenetic relationship between SM22α and the calponin family supports that SM22α is a calponin-like regulatory protein. The level of SM22α is decreased in skin fibroblasts isolated from calponin 2 knockout mice, suggesting interrelated regulation and function of the two proteins. On the other hand, SM22α expression was maximized at a matrix stiffness higher than that for calponin 2 in the same cell type, indicating differentiated regulation and tension responsiveness. The novel mechanoregulation of SM22α/transgelin lays the groundwork for understanding its cellular functions.

NanoLC-MS coupling of liquid microjunction microextraction for on-tissue proteomic analysis

Mass spectrometry (MS)-based microproteomics on localized regions of tissue sections was achieved by direct coupling of liquid microjunction microextraction with a nanoscale liquid chromatography-tandem MS, resulting in the identification of >500 protein groups from a region as small as 250μm in diameter representing only a few hundred of cells. The method was applied on the examination of benign and tumor regions initially defined by imaging mass spectrometry (IMS) analysis of a consecutive high grade serous ovarian tumor tissue section. Results identified the higher abundance of eukaryotic translation initiation factors eIF4A, its isoform eIF4A2, and eIF5A and its isoform eIF5A2, and lower abundance of actin-binding proteins OBSCN, TAGLN and CNN3 on tumor regions, concomitant with previous findings. This demonstrates the use of the method for downstream characterization of distinct regions identified by IMS. This article is part of a Special Issue entitled: MALDI Imaging, edited by Dr. Corinna Henkel and Prof. Peter Hoffmann.

Knockdown of calponin 2 suppressed cell growth in gastric cancer cells

Calponin family members are actin filament-associated regulatory proteins with distinct expression patterns. Previous studies on CNN2 (calponin 2) have demonstrated that CNN2 is expressed in a broad range of tissues and cell types, exhibiting potential regulatory roles in a number of cellular activities, including cell proliferation, cell migration, and platelet adhesion. In this work, we found that both messenger RNA and protein expression levels of CNN2 were remarkably upregulated in 60%-70% of gastric cancer tissues by comparison with those of neighboring non-tumorous mucosa. By utilizing specific shCNN2 (small hairpin RNA targeting CNN2), the potential role of CNN2 in regulating AGS gastric cancer cell growth was then further investigated. AGS cells infected with shCNN2 exhibited significantly decreased cell growth ability by comparison with control cells in vitro. Moreover, while there was no obvious difference in cell cycle distribution between two groups, enhanced cell apoptosis was detected in cells with reduced CNN2 expression. Consistently, caspase 3/7 activity was also remarkably activated upon shCNN2 lentivirus infection. Taken together, our results demonstrated that knockdown of endogenous CNN2 in AGS cells could significantly activate cell apoptosis pathway and therefore suppress cell growth in vitro. The deletion of CNN2 might be a potential therapeutic approach to inhibit aggressive growth of gastric cancer.

A Rho-associated coiled-coil containing kinases (ROCK) inhibitor, Y-27632, enhances adhesion, viability and differentiation of human term placenta-derived trophoblasts in vitro

Although human term placenta-derived primary cytotrophoblasts (pCTBs) represent a good human syncytiotrophoblast (STB) model, in vitro culture of pCTBs is not always easily accomplished. Y-27632, a specific inhibitor of Rho-associated coiled-coil containing kinases (ROCK), reportedly prevented apoptosis and improved cell-to-substrate adhesion and culture stability of dissociated cultured human embryonic stem cells and human corneal endothelial cells. The Rho kinase pathway regulates various kinds of cell behavior, some of which are involved in pCTB adhesion and differentiation. In this study, we examined Y-27632's potential for enhancing pCTB adhesion, viability and differentiation. pCTBs were isolated from term, uncomplicated placentas by trypsin-DNase I-Dispase II treatment and purified by HLA class I-positive cell depletion. Purified pCTBs were cultured on uncoated plates in the presence of epidermal growth factor (10 ng/ml) and various concentrations of Y-27632. pCTB adhesion to the plates was evaluated by phase-contrast imaging, viability was measured by WST-8 assay, and differentiation was evaluated by immunofluorescence staining, expression of fusogenic genes and hCG-β production. Ras-related C3 botulinum toxin substrate 1 (Rac1; one of the effector proteins of the Rho family) and protein kinase A (PKA) involvement was evaluated by using their specific inhibitors, NSC-23766 and H-89. We found that Y-27632 treatment significantly enhanced pCTB adhesion to plates, viability, cell-to-cell fusion and hCG-β production, but showed no effects on pCTB proliferation or apoptosis. Furthermore, NSC-23766 and H-89 each blocked the effects of Y-27632, suggesting that Y-27632 significantly enhanced pCTB differentiation via Rac1 and PKA activation. Our findings suggest that Rac1 and PKA may be interactively involved in CTB differentiation, and addition of Y-27632 to cultures may be an effective method for creating a stable culture model for studying CTB and STB biology in vitro.

RNA-Seq Analysis of the Antioxidant Status and Immune Response of Portunus trituberculatus Following Aerial Exposure

Desiccation tolerance has been long considered as an important trait for the life survival under acute environmental stress. One of the biggest problems for modern commercial crab farming is desiccation during transportation; high mortality could occur following the aerial exposure. In this regard, here, we utilized RNA-seq-based transcriptome profiling to characterize the molecular responses of swimming crab in response to aerial exposure. In present study, following aerial exposure, the gill samples were sequenced at 0, 6, 12, and 18 h. And the sequenced reads were assembled into 274,594 contigs, with average length of 735.59 bp and N50 size of 1262 bp. After differential expression analysis, a total of 1572 genes were captured significantly differentially expressed, and were categorized into antioxidant/oxidative stress response, chaperones/heat shock proteins, immune alteration, cell proliferation/apoptosis, and cytoskeletal. Our analysis revealed the dramatic tissue oxidant stress and the alteration of the tissue epithelial integrity, especially many genes that have not been reported in crab species. With the limited functional information in crab, further studies are needed and underway in our lab to further characterize the key cellular actors governing the crab tolerance to aerial exposure. Taken together, our results provide molecular resources for further identification of key genes for desiccation tolerance, and to facilitate the molecular selection and breeding of desiccation tolerant strain and family.

Deletion of Calponin 2 in Mouse Fibroblasts Increases Myosin II-Dependent Cell Traction Force

Cell traction force (CTF) plays a critical role in controlling cell shape, permitting cell motility, and maintaining cellular homeostasis in many biological processes such as angiogenesis, development, wound healing, and cancer metastasis. Calponin is an actin filament-associated cytoskeletal protein in smooth muscles and multiple types of non-muscle cells. An established biochemical function of calponin is the inhibition of myosin ATPase in smooth muscle cells. Vertebrates have three calponin isoforms. Among them, calponin 2 is expressed in epithelial cells, endothelial cells, macrophages, myoblasts, and fibroblasts and plays a role in regulating cytoskeleton activities such as cell adhesion, migration, and cytokinesis. Knockout (KO) of the gene encoding calponin 2 (Cnn2) in mice increased cell motility, suggesting a function of calponin 2 in modulating CTF. In this study, we examined fibroblasts isolated from Cnn2 KO and wild-type (WT) mice using CTF microscopy. Primary mouse fibroblasts were cultured on polyacrylamide gel substrates embedded with fluorescent beads to measure root-mean-square traction, total strain energy, and net contractile movement. The results showed that calponin 2-null fibroblasts exhibit traction force greater than that of WT cells. Adherent calponin 2-null fibroblasts de-adhered faster than the WT control during mild trypsin treatment, consistent with an increased CTF. Blebbistatin, an inhibitor of myosin II ATPase, is more effective upon an alteration in cell morphology when calponin 2 is present in WT fibroblasts than that on Cnn2 KO cells, indicating their additive effects in inhibiting myosin motor activity. The novel finding that calponin 2 regulates myosin-dependent CTF in non-muscle cells demonstrates a mechanism for controlling cell motility-based functions.

Deep RNA sequencing analysis of syncytialization-related genes during BeWo cell fusion

The syncytiotrophoblast (STB) plays a key role in maintaining the function of the placenta during human pregnancy. However, the molecular network that orchestrates STB development remains elusive. The aim of this study was to obtain broad and deep insight into human STB formation via transcriptomics. We adopted RNA sequencing (RNA-Seq) to investigate genes and isoforms involved in forskolin (FSK)-induced fusion of BeWo cells. BeWo cells were treated with 50 μM FSK or dimethylsulfoxide (DMSO) as a vehicle control for 24 and 48 h, and the mRNAs at 0, 24 and 48 h was sequenced. We detected 28,633 expressed genes and identified 1,902 differentially expressed genes (DEGs) after FSK treatment for 24 and 48 h. Among the 1,902 DEGs, 461 were increased and 395 were decreased at 24 h, while 879 were up-regulated and 763 were down-regulated at 48 h. When the 856 DEGs identified at 24 h were traced individually at 48 h, they separated into 6 dynamic patterns via a K-means algorithm, and most were enriched in down-even and up-even patterns. Moreover, the Gene Ontology (GO) terms syncytium formation, cell junction assembly, cell fate commitment, calcium ion transport, regulation of epithelial cell differentiation and cell morphogenesis involved in differentiation were clustered, and the MAPK pathway was most significantly regulated. Analyses of alternative splicing isoforms detected 123,200 isoforms, of which 1,376 were differentially expressed. The present deep analysis of the RNA-Seq data of BeWo cell fusion provides important clues for understanding the mechanisms underlying human STB formation.

MEKK1-dependent phosphorylation of calponin-3 tunes cell contractility

MEKK1 (also known as MAP3K1), which plays a major role in MAPK signaling, has been implicated in mechanical processes in cells, such as migration. Here, we identify the actin-binding protein calponin-3 as a new MEKK1 substrate in the signaling that regulates actomyosin-based cellular contractility. MEKK1 colocalizes with calponin-3 at the actin cytoskeleton and phosphorylates it, leading to an increase in the cell-generated traction stress. MEKK1-mediated calponin-3 phosphorylation is attenuated by the inhibition of myosin II activity, the disruption of actin cytoskeletal integrity and adhesion to soft extracellular substrates, whereas it is enhanced upon cell stretching. Our results reveal the importance of the MEKK1-calponin-3 signaling pathway to cell contractility.

Deletion of calponin 2 in macrophages alters cytoskeleton-based functions and attenuates the development of atherosclerosis

Arterial atherosclerosis is an inflammatory disease. Macrophages play a major role in the pathogenesis and progression of atherosclerotic lesions. Modulation of macrophage function is a therapeutic target for the treatment of atherosclerosis. Calponin is an actin-filament-associated regulatory protein that inhibits the activity of myosin-ATPase and dynamics of the actin cytoskeleton. Encoded by the gene Cnn2, calponin isoform 2 is expressed at significant levels in macrophages. Deletion of calponin 2 increases macrophage migration and phagocytosis. In the present study, we investigated the effect of deletion of calponin 2 in macrophages on the pathogenesis and development of atherosclerosis. The results showed that macrophages isolated from Cnn2 knockout mice ingested a similar level of acetylated low-density lipoprotein (LDL) to that of wild type (WT) macrophages but the resulting foam cells had significantly less hindered velocity of migration. Systemic or myeloid cell-specific Cnn2 knockouts effectively attenuated the development of arterial atherosclerosis lesions with less macrophage infiltration in apolipoprotein E knockout mice. Consistently, calponin 2-null macrophages produced less pro-inflammatory cytokines than that of WT macrophages, and the up-regulation of pro-inflammatory cytokines in foam cells was also attenuated by the deletion of calponin 2. Calponin 2-null macrophages and foam cells have significantly weakened cell adhesion, indicating a role of cytoskeleton regulation in macrophage functions and inflammatory responses, and a novel therapeutic target for the treatment of arterial atherosclerosis.

Deletion of calponin 2 in macrophages attenuates the severity of inflammatory arthritis in mice

Calponin is an actin cytoskeleton-associated protein that regulates motility-based cellular functions. Three isoforms of calponin are present in vertebrates, among which calponin 2 encoded by the Cnn2 gene is expressed in multiple types of cells, including blood cells from the myeloid lineage. Our previous studies demonstrated that macrophages from Cnn2 knockout (KO) mice exhibit increased migration and phagocytosis. Intrigued by an observation that monocytes and macrophages from patients with rheumatoid arthritis had increased calponin 2, we investigated anti-glucose-6-phosphate isomerase serum-induced arthritis in Cnn2-KO mice for the effect of calponin 2 deletion on the pathogenesis and pathology of inflammatory arthritis. The results showed that the development of arthritis was attenuated in systemic Cnn2-KO mice with significantly reduced inflammation and bone erosion than that in age- and stain background-matched C57BL/6 wild-type mice. In vitro differentiation of calponin 2-null mouse bone marrow cells produced fewer osteoclasts with decreased bone resorption. The attenuation of inflammatory arthritis was confirmed in conditional myeloid cell-specific Cnn2-KO mice. The increased phagocytotic activity of calponin 2-null macrophages may facilitate the clearance of autoimmune complexes and the resolution of inflammation, whereas the decreased substrate adhesion may reduce osteoclastogenesis and bone resorption. The data suggest that calponin 2 regulation of cytoskeleton function plays a novel role in the pathogenesis of inflammatory arthritis, implicating a potentially therapeutic target.

Calponin isoforms CNN1, CNN2 and CNN3: Regulators for actin cytoskeleton functions in smooth muscle and non-muscle cells

Calponin is an actin filament-associated regulatory protein expressed in smooth muscle and many types of non-muscle cells. Three homologous genes, CNN1, CNN2 and CNN3, encoding calponin isoforms 1, 2, and 3, respectively, are present in vertebrate species. All three calponin isoforms are actin-binding proteins with functions in inhibiting actin-activated myosin ATPase and stabilizing the actin cytoskeleton, while each isoform executes different physiological roles based on their cell type-specific expressions. Calponin 1 is specifically expressed in smooth muscle cells and plays a role in fine-tuning smooth muscle contractility. Calponin 2 is expressed in both smooth muscle and non-muscle cells and regulates multiple actin cytoskeleton-based functions. Calponin 3 participates in actin cytoskeleton-based activities in embryonic development and myogenesis. Phosphorylation has been extensively studied for the regulation of calponin functions. Cytoskeleton tension regulates the transcription of CNN2 gene and the degradation of calponin 2 protein. This review summarizes our knowledge learned from studies over the past three decades, focusing on the evolutionary lineage of calponin isoform genes, their tissue- and cell type-specific expressions, structure-function relationships, and mechanoregulation.

Scrutinising the regulators of syncytialization and their expression in pregnancy-related conditions

The placenta is important for the success of gestation and foetal development. In fact, this specialized pregnancy organ is essential for foetal nourishment, support, and protection. In the placenta, there are different cell populations, including four subtypes of trophoblasts. Cytotrophoblasts fuse and differentiate into the multinucleated syncytiotrophoblast (syncytialization). Syncytialization is a hallmark of placentation and is highly regulated by numerous molecules with distinct roles. Placentas from pregnancies complicated by preeclampsia, intrauterine growth restriction or trisomy 21 have been associated with a defective syncytialization and an altered expression of its modulators. This work proposes to review the molecules that promote or inhibit both fusion and biochemical differentiation of cytotrophoblasts. Moreover, it will also analyse the syncytialization modulators abnormally expressed in pathological placentas, highlighting the molecules that may contribute to the aetiology of these diseases.

Placenta: the forgotten organ

The placenta sits at the interface between the maternal and fetal vascular beds where it mediates nutrient and waste exchange to enable in utero existence. Placental cells (trophoblasts) accomplish this via invading and remodeling the uterine vasculature. Amazingly, despite being of fetal origin, trophoblasts do not trigger a significant maternal immune response. Additionally, they maintain a highly reliable hemostasis in this extremely vascular interface. Decades of research into how the placenta differentiates itself from embryonic tissues to accomplish these and other feats have revealed a previously unappreciated level of complexity with respect to the placenta's cellular composition. Additionally, novel insights with respect to roles played by the placenta in guiding fetal development and metabolism have sparked a renewed interest in understanding the interrelationship between fetal and placental well-being. Here, we present an overview of emerging research in placental biology that highlights these themes and the importance of the placenta to fetal and adult health.

A Conditional Knockout Mouse Model Reveals That Calponin-3 Is Dispensable for Early B Cell Development

Calponins form an evolutionary highly conserved family of actin filament-associated proteins expressed in both smooth muscle and non-muscle cells. Whereas calponin-1 and calponin-2 have already been studied to some extent, little is known about the role of calponin-3 under physiological conditions due to the lack of an appropriate animal model. Here, we have used an unbiased screen to identify novel proteins implicated in signal transduction downstream of the precursor B cell receptor (pre-BCR) in B cells. We find that calponin-3 is expressed throughout early B cell development, localizes to the plasma membrane and is phosphorylated in a Syk-dependent manner, suggesting a putative role in pre-BCR signaling. To investigate this in vivo, we generated a floxed calponin-3-GFP knock-in mouse model that enables tracking of cells expressing calponin-3 from its endogenous promoter and allows its tissue-specific deletion. Using the knock-in allele as a reporter, we show that calponin-3 expression is initiated in early B cells and increases with their maturation, peaking in the periphery. Surprisingly, conditional deletion of the Cnn3 revealed no gross defects in B cell development despite this regulated expression pattern and the in vitro evidence, raising the question whether other components may compensate for its loss in lymphocytes. Together, our work identifies calponin-3 as a putative novel mediator downstream of the pre-BCR. Beyond B cells, the mouse model we generated will help to increase our understanding of calponin-3 in muscle and non-muscle cells under physiological conditions.

Involvement of nephrin in human placental trophoblast syncytialization

The placenta has numerous functions, such as transporting oxygen and nutrients and building the immune tolerance of the fetus. Cell fusion is an essential process for placental development and maturation. In human placental development, mononucleated cytotrophoblast (CTB) cells can fuse to form a multinucleated syncytiotrophoblast (STB), which is the outermost layer of the placenta. Nephrin is a transmembrane protein that belongs to the Ig superfamily. Previous studies have shown that nephrin contributes to the fusion of myoblasts into myotubes in zebrafish and mice, presenting a functional conservation with its Drosophila ortholog sticks and stones. However, whether nephrin is involved in trophoblast syncytialization remains unclear. In this study, we report that nephrin was localized predominantly in the CTB cells and STB of human placenta villi from first trimester to term pregnancy. Using a spontaneous fusion model of primary CTB cells, the expression of nephrin was found to be increased during trophoblast cell fusion. Moreover, the spontaneous syncytialization and the expression of syncytin 2, connexin 43, and human chorionic gonadotropin beta were significantly inhibited by nephrin-specific siRNAs. The above results demonstrate that nephrin plays an important role in trophoblast syncytialization.