MLK3 Limits Activated Gαq Signaling to Rho by Binding to p63RhoGEF

Mixed lineage kinase 3 (MLK3) is a MAP3K that activates the JNK-dependent MAPK pathways. Here we show that MLK3 is required for cell migration in a manner independent of its role as a MAP3K or MLK3 kinase activity. Rather, MLK3 functions in a regulated way to limit levels of the activated GTPase, Rho, by binding to the Rho activator, p63RhoGEF/GEFT, which, in turn, prevents its activation by Gαq. These findings demonstrate a scaffolding role for MLK3 in controlling the extent of Rho activation that modulates cell migration. Moreover, they suggest that MLK3 functions as a network hub that links a number of signaling pathways

Comparison of murine cervicovaginal infection by chlamydial strains: Identification of extrusions shed in vivo

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections (STIs) and preventable blindness. Untreated, asymptomatic infection as well as frequent re-infection are common and may drive pelvic inflammatory disease, ectopic pregnancy, and infertility. In vivo models of chlamydial infection continue to be instrumental in progress toward a vaccine and further elucidating the pathogenesis of this intracellular bacterium, however significant gaps in our understanding remain. Chlamydial host cell exit occurs via two mechanisms, lysis and extrusion, although the latter has yet to be reported in vivo and its biological role is unclear. The objective of this study was to investigate whether chlamydial extrusions are shed in vivo following infection with multiple strains of Chlamydia. We utilized an established C3H/HeJ murine cervicovaginal infection model with C. trachomatis serovars D and L2 and the Chlamydia muridarum strain MoPn to monitor the (i) time course of infection and mode of host cell exit, (ii) mucosal and systemic immune response to infection, and (iii) gross and histopathology following clearance of active infection. The key finding herein is the first identification of chlamydial extrusions shed from host cells in an in vivo model. Extrusions, a recently appreciated mode of host cell exit and potential means of dissemination, had been previously observed solely in vitro. The results of this study demonstrate that chlamydial extrusions exist in vivo and thus warrant further investigation to determine their role in chlamydial pathogenesis.Peer reviewedIntegrative BiologyMicrobiology and Molecular GeneticsVeterinary Pathobiolog

Autocrine IL-10 activation of the STAT3 pathway is required for pathological macrophage differentiation in polycystic kidney disease

Polycystic kidney disease (PKD) is characterized by slow expansion of fluid-filled cysts derived from tubules within the kidney. Cystic expansion results in injury to surrounding parenchyma and leads to inflammation, scarring and ultimately loss of renal function. Macrophages are a key element in this process, promoting cyst epithelial cell proliferation, cyst expansion and disease progression. Previously, we have shown that the microenvironment established by cystic epithelial cells can ‘program’ macrophages, inducing M2-like macrophage polarization that is characterized by expression of markers that include Arg1 and Il10. Here, we functionally characterize these macrophages, demonstrating that their differentiation enhances their ability to promote cyst cell proliferation. This observation indicates a model of reciprocal pathological interactions between cysts and the innate immune system: cyst epithelial cells promote macrophage polarization to a phenotype that, in turn, is especially efficient in promoting cyst cell proliferation and cyst growth. To better understand the genesis of this macrophage phenotype, we examined the role of IL-10, a regulatory cytokine shown to be important for macrophage-stimulated tissue repair in other settings. Herein, we show that the acquisition of the pathological macrophage phenotype requires IL-10 secretion by the macrophages. Further, we demonstrate a requirement for IL-10-dependent autocrine activation of the STAT3 pathway. These data suggest that the IL-10 pathway in macrophages plays an essential role in the pathological relationship between cysts and the innate immune system in PKD, and thus could be a potential therapeutic target

Macrophages promote polycystic kidney disease progression

Renal M2-like macrophages have critical roles in tissue repair stimulating tubule cell proliferation and, if they remain, fibrosis. M2-like macrophages have also been implicated in promoting cyst expansion in mouse models of autosomal dominant polycystic kidney disease (ADPKD). While renal macrophages have been documented in human ADPKD, there are no studies in autosomal recessive polycystic kidney disease (ARPKD). Here we evaluated the specific phenotype of renal macrophages and their disease-impacting effects on cystic epithelial cells. We found an abundance of M2-like macrophages in the kidneys of patients with either ADPKD or ARPKD and in the cystic kidneys of cpk mice, a model of ARPKD. Renal epithelial cells from either human ADPKD cysts or non-cystic human kidneys promote differentiation of naive macrophages to a distinct M2-like phenotype in culture. Reciprocally, these immune cells stimulate the proliferation of renal tubule cells and microcyst formation in vitro. Further, depletion of macrophages from cpk mice indicated that macrophages contribute to PKD progression regardless of the genetic etiology. Thus M2-like macrophages are two-pronged progression factors in PKD promoting cyst cell proliferation, cyst growth, and fibrosis. Agents that block the emergence of these cells or their effects in the cystic kidney may be effective therapies for slowing PKD progression

Epidemiology of US High School Sports-Related Fractures, 2005-2009

Objective: To describe the epidemiology of fractures among US high school athletes participating in 9 popular sports. Design: Descriptive epidemiologic study. Setting: Sports injury data for the 2005-2009 academic years were collected using an Internet-based injury surveillance system, Reporting Information Online (RIO). Participants: A nationally representative sample of 100 US high schools. Assessment of risk factors: Injuries sustained as a function of sport and sex. Main outcome measures: Fracture injury rates, body site, outcome, surgery, and mechanism. Results: Fractures (n = 568 177 nationally) accounted for 10.1% of all injuries sustained by US high school athletes. The highest rate of fractures was in football (4.61 per 10 000 athlete exposures) and the lowest in volleyball (0.52). Boys were more likely than girls to sustain a fracture in basketball (rate ratio, 1.35,; 95% confidence interval, 1.06-1.72) and soccer (rate ratio, 1.34; 95% confidence interval, 1.05-1.71). Overall, the most frequently fractured body sites were the hand/finger (28.3%), wrist (10.4%), and lower leg (9.3%). Fractures were the most common injury to the nose (76.9%), forearm (56.4%), hand/finger (41.7%), and wrist (41.6%). Most fractures resulted in \u3e3 weeks time lost (34.3%) or a medical disqualification from participation (24.2%) and were more likely to result in \u3e3 weeks time lost and medical disqualification than all other injuries combined. Fractures frequently required expensive medical diagnostic imaging examinations such as X-ray, computed tomographic scan, and magnetic resonance imaging. Additionally, 16.1% of fractures required surgical treatment, accounting for 26.9% of all injuries requiring surgery. Illegal activity was noted in 9.3% of all fractures with the highest proportion of fractures related to illegal activity in girls soccer (27.9%). Conclusions: Fractures are a major concern for US high school athletes. They can severely affect the athlete\u27s ability to continue sports participation and can impose substantial medical costs on the injured athletes families. Targeted, evidence-based, effective fracture prevention programs are needed

Macrophage migration inhibitory factor promotes cyst growth in polycystic kidney disease

Functional Genomics of Systemic Disorder