ARHGEF18/p114RhoGEF Coordinates PKA/CREB Signaling and Actomyosin Remodeling to Promote Trophoblast Cell-Cell Fusion During Placenta Morphogenesis

Coordination of cell-cell adhesion, actomyosin dynamics and gene expression is crucial for morphogenetic processes underlying tissue and organ development. Rho GTPases are main regulators of the cytoskeleton and adhesion. They are activated by guanine nucleotide exchange factors in a spatially and temporally controlled manner. However, the roles of these Rho GTPase activators during complex developmental processes are still poorly understood. ARHGEF18/p114RhoGEF is a tight junction-associated RhoA activator that forms complexes with myosin II, and regulates actomyosin contractility. Here we show that p114RhoGEF/ARHGEF18 is required for mouse syncytiotrophoblast differentiation and placenta development. In vitro and in vivo experiments identify that p114RhoGEF controls expression of AKAP12, a protein regulating protein kinase A (PKA) signaling, and is required for PKA-induced actomyosin remodeling, cAMP-responsive element binding protein (CREB)-driven gene expression of proteins required for trophoblast differentiation, and, hence, trophoblast cell-cell fusion. Our data thus indicate that p114RhoGEF links actomyosin dynamics and cell-cell junctions to PKA/CREB signaling, gene expression and cell-cell fusion

Urocortin protects chondrocytes from NO-induced apoptosis: a future therapy for osteoarthritis?

Osteoarthritis (OA) is characterized by a loss of joint mobility and pain resulting from progressive destruction and loss of articular cartilage secondary to chondrocyte death and/ or senescence. Certain stimuli including nitric oxide (NO) and the pro-inflammatory cytokine tumor necrosis factor α (TNF-α have been implicated in this chondrocyte death and the subsequent accelerated damage to cartilage. In this study, we demonstrate that a corticotrophin releasing factor (CRF) family peptide, urocortin (Ucn), is produced by a human chondrocyte cell line, C-20/A4, and acts both as an endogenous survival signal and as a cytoprotective agent reducing the induction of apoptosis by NO but not TNF-α when added exogenously. Furthermore, treatment with the NO donor S-nitroso-N-acetyl-D-L-penicillamine upregulates chondrocyte Ucn expression, whereas treatment with TNF-α does not. The chondroprotective effects of Ucn are abolished by both specific ligand depletion (with an anti-Ucn antibody) and by CRF receptor blockade with the pan-CRFR antagonist α-helical CRH(9-41). CRFR expression was confirmed by reverse transcription-PCR with subsequent amplicon sequence analysis and demonstrates that C-20/A4 cells express both CRFR1 and CRFR2, specifically CRFR1α and CRFR2β. Protein expression of these receptors was confirmed by western blotting. The presence of both Ucn and its receptors in these cells, coupled with the induction of Ucn by NO, suggests the existence of an endogenous autocrine/paracrine chondroprotective mechanism against stimuli inducing chondrocyte apoptosis via the intrinsic/mitochondrial pathway

Alternative splicing: an important mechanism for myometrial gene regulation that can be manipulated to target specific genes associated with preterm labour

Considerable effort has been expended in attempting to distinguish genes that contribute to initiating the onset of term and preterm labour (PTL) from those that change in expression as a consequence of the progression of labour. The ability to define more clearly the genes involved in triggering labour contractions should lead to the development of new effective and safer strategies to prevent preterm birth. There is ample evidence to suggest that specific genes are co-ordinately regulated within the upper and lower regions of the myometrium prior to and during parturition and many of these genes are regulated by alternative pre-mRNA splicing. This mini-review highlights that expression of a range of different splicing factors, with defined roles in pre-mRNA splicing, is both temporally and spatially regulated within the uterine smooth muscle during pregnancy and labour. Moreover, several of these splicing factors play key roles in controlling the differential expression of specific regulatory proteins involved in uterine signalling and uterine quiescence. In addition, antisense morpholino oligonucleotide manipulation of pre-mRNA splicing may have potential in defining and targeting uterine pro-labour genes and thus contribute to the development of new therapeutic approaches to prevent PTL

Chondroprotection by urocortin involves blockade of the mechanosensitive ion channel Piezo1

Osteoarthritis (OA) is characterised by progressive destruction of articular cartilage and chondrocyte cell death. Here, we show the expression of the endogenous peptide urocortin1 (Ucn1) and two receptor subtypes, CRF-R1 and CRF-R2, in primary human articular chondrocytes (AC) and demonstrate its role as an autocrine/paracrine pro-survival factor. This effect could only be removed using the CRF-R1 selective antagonist CP-154526, suggesting Ucn1 acts through CRF-R1 when promoting chondrocyte survival. This cell death was characterised by an increase in p53 expression, and cleavage of caspase 9 and 3. Antagonism of CRF-R1 with CP-154526 caused an accumulation of intracellular calcium (Ca2+) over time and cell death. These effects could be prevented with the non-selective cation channel blocker Gadolinium (Gd3+). Therefore, opening of a non-selective cation channel causes cell death and Ucn1 maintains this channel in a closed conformation. This channel was identified to be the mechanosensitive channel Piezo1. We go on to determine that this channel inhibition by Ucn1 is mediated initially by an increase in cyclic adenosine monophosphate (cAMP) and a subsequent inactivation of phospholipase A2 (PLA2), whose metabolites are known to modulate ion channels. Knowledge of these novel pathways may present opportunities for interventions that could abrogate the progression of OA

Conditional corticotropin-releasing hormone overexpression in the mouse forebrain enhances rapid eye movement sleep

Impaired sleep and enhanced stress hormone secretion are the hallmarks of stress-related disorders, including major depression. The central neuropeptide, corticotropin-releasing hormone (CRH), is a key hormone that regulates humoral and behavioral adaptation to stress. Its prolonged hypersecretion is believed to play a key role in the development and course of depressive symptoms, and is associated with sleep impairment. To investigate the specific effects of central CRH overexpression on sleep, we used conditional mouse mutants that overexpress CRH in the entire central nervous system (CRH-COE-Nes) or only in the forebrain, including limbic structures (CRH-COE-Cam). Compared with wild-type or control mice during baseline, both homozygous CRH-COE-Nes and -Cam mice showed constantly increased rapid eye movement (REM) sleep, whereas slightly suppressed non-REM sleep was detected only in CRH-COE-Nes mice during the light period. In response to 6-h sleep deprivation, elevated levels of REM sleep also became evident in heterozygous CRH-COE-Nes and -Cam mice during recovery, which was reversed by treatment with a CRH receptor type 1 (CRHR1) antagonist in heterozygous and homozygous CRH-COE-Nes mice. The peripheral stress hormone levels were not elevated at baseline, and even after sleep deprivation they were indistinguishable across genotypes. As the stress axis was not altered, sleep changes, in particular enhanced REM sleep, occurring in these models are most likely induced by the forebrain CRH through the activation of CRHR1. CRH hypersecretion in the forebrain seems to drive REM sleep, supporting the notion that enhanced REM sleep may serve as biomarker for clinical conditions associated with enhanced CRH secretion

Intratumoral CRH modulates immuno-escape of ovarian cancer cells through FasL regulation

Although corticotropin-releasing hormone (CRH) and Fas ligand (FasL) have been documented in ovarian carcinoma, a clear association with tumour progression and immuno-escape has not been established. FasL plays an important role in promoting tumour cells' ability to counterattack immune cells. Here, we examined immunohistochemically the expression of CRH, CRHR1, CRHR2 and FasL in 47 human ovarian cancer cases. The ovarian cancer cell lines OvCa3 and A2780 were further used to test the hypothesis that CRH might contribute to the immune privilege of ovarian tumours, by modulating FasL expression on the cancer cells. We found that CRH, CRHR1, CRHR2 and FasL were expressed in 68.1, 70.2, 63.8 and 63.8% of the cases respectively. Positivity for CRH or FasL expression was associated with higher tumour stage. Finally, CRH increased the expression of FasL in OvCa3 and A2780 cells through CRHR1 thereby potentiated their ability to induce apoptosis of activated peripheral blood lymphocytes. Corticotropin-releasing hormone produced by human ovarian cancer might favour survival and progression of the tumour by promoting its immune privilege. These findings support the hypothesis that CRHR1 antagonists could potentially be used against ovarian cancer

The effect of type of femoral component fixation on mortality and morbidity after hip hemiarthroplasty:A systematic review and meta-analysis

Background: Hip hemiarthroplasty is a well-established treatment of displaced femoral neck fracture, although debate exists over whether cemented or uncemented fixation is superior. Uncemented prostheses have typically been used in younger, healthier patients and cemented prostheses in older patients with less-stable bone. Also, earlier research has suggested that bone cement has cytotoxic effects and may trigger cardiovascular and respiratory adverse events. Questions/Purposes: The aim of this systematic review and meta-analysis was to compare morbidity and mortality rates after cemented and uncemented hemiarthroplasty for the treatment of displaced femoral neck fractures in elderly patients. Methods: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched seven medical databases for randomized clinical trials and observational studies. We compared cemented and uncemented hemiarthroplasty using the Harris Hip Score (HHS), as well as measures of postoperative pain, mortality, and complications. Data were extracted and pooled as risk ratios or standardized mean difference with their corresponding 95% confidence intervals in a meta-analysis model. Results: The meta-analysis included 34 studies (12 randomized trials and 22 observational studies), with a total of 42,411 patients. In the pooled estimate, cemented hemiarthroplasty was associated with less risk of postoperative pain than uncemented hemiarthroplasty. There were no significant differences between groups regarding HHS or rates of postoperative mortality, pulmonary embolism, cardiac arrest, myocardial infarction, acute cardiac arrhythmia, or deep venous thrombosis. Conclusions: While we found that cemented hemiarthroplasty results in less postoperative pain than uncemented hemiarthroplasty in older patients with femoral neck fracture, the lack of significant differences in functional hip scores, mortality, and complications was surprising. Further high-level research is needed