Communicated by Maria Rita Passos-BuenoPulmonary arterial hypertension (PAH) is clinically characterized by a sustained elevation in mean pulmonary artery pressure leading to significant morbidity and mortality. The disorder is typically sporadic, and in such cases the term idiopathic PAH (IPAH) is used. However, cases that occur within families (familial PAH (FPAH)) display similar clinical and histopathological features, suggesting a common etiology. Heterozygous mutations of a type II member of the TGF-b cell signaling superfamily known as BMPR2 on chromosome 2q33 have been identified in many kindreds with FPAH, yet display both reduced penetrance and sex bias. This report presents the compilation of data for 144 distinct mutations that alter the coding sequence of the BMPR2 gene identified in 210 independent PAH subjects. This large data set characterizes the extent of sequence variation and reveals that the majority (71%) of mutations in FPAH and IPAH comprise nonsense, frameshift, and splice-site defects, and gene rearrangements. These predict premature termination of the transcript with likely loss through the process of nonsense-mediated decay (NMD). A total of 44 missense mutations were identified that substitute amino acid residues at highly conserved sites within recognized functional domains of the mature receptor. We assess this category of mutations in the context of their heterogeneous effects on cell signaling when assayed by in vitro cell-based systems. Disease-causing mutation hot-spots within BMPR2 are summarized. Taken together, these observations are likely to aid in the development of targeted mutation detection strategies relevant for patient management. Finally, we examine the age-and sex-dependent reduced penetrance of BMPR2 mutations by reviewing bmpr2 animal models and the requirement for additional genetic and/or environmental modifiers of disease. In conclusion, these data provide compelling genetic evidence that haploinsufficiency is the predominant molecular mechanism underlying disease predisposition, and support the

BackgroundEngagement with community adolescent treatment supporters (CATS) improves adherence, psychosocial well-being, linkage and retention in care among adolescents living with HIV. However, there is an urgent need for empirical evidence of the effectiveness of this approach, in order to inform further programmatic development, national and international policy, guidelines and service delivery for adolescents living with HIV. This study set out to determine the effectiveness of CATS services on improving linkage to services and retention in care, adherence and psychosocial well-being among adolescents living with HIV in Zimbabwe.MethodsA randomised trial was conducted in Gokwe South district, Zimbabwe over a period of 12 months. Ninety-four HIV-positive adolescents, 10–15 years old, on antiretroviral therapy were recruited to the study. 47 participants received standard of care from the Ministry of Health and Child Care and 47 received the same standard of care plus CATS services. Data collection involved a questionnaire which was administered at baseline then repeated at three, six, nine and twelve months for all participants. Survey questions on confidence, self-esteem and self-worth had a three-point Likert scale. Stigma, quality of life and the linkages to services and retention questions had a five-point Likert scale.ResultsSurvey questionnaires were completed with response rates of 40 out of 47 (85%) for the intervention arm, and 28 out of 47 (60%) for the control arm, at end-line. The intervention group were 3.9 times more likely to adhere to treatment compared to the control group. Linkage to services and retention in care within the intervention group increased compared with a decrease in the control arm. The intervention group reported a statistically significant increase in confidence, self-esteem, self-worth (p < 0.001) and quality of life compared (p = 0.028) with a decrease in the control arm.ConclusionsThis study found that adolescents receiving the CATS service had improved linkage to services and retention in care, improved adherence and improved psychosocial well-being compared to adolescents who did not have access to such services.Trial registrationPACTR201711002755428. Registered 11 November 2017. Retrospectively registered.

Abstract-Heterozygous germline mutations in the gene encoding the bone morphogenetic protein type II (BMPR-II) receptor underlie the majority (Ͼ70%) of cases of familial pulmonary arterial hypertension (FPAH), and dysfunction of BMP signaling has been implicated in other forms of PAH. The reduced disease gene penetrance in FPAH indicates that other genetic and/or environmental factors may also be required for the clinical manifestation of disease. Of these, the serotonin pathway has been implicated as a major factor in PAH pathogenesis. We investigated the pulmonary circulation of mice deficient in BMPR-II (BMPR2 ϩ/Ϫ mice) and show that pulmonary hemodynamics and vascular morphometry of BMPR2 ϩ/Ϫ mice were similar to wild-type littermate controls under normoxic or chronic hypoxic (2-to 3-week) conditions. However, chronic infusion of serotonin caused increased pulmonary artery systolic pressure, right ventricular hypertrophy, and pulmonary artery remodeling in BMPR2 ϩ/Ϫ mice compared with wild-type littermates, an effect that was exaggerated under hypoxic conditions. In addition, pulmonary, but not systemic, resistance arteries from BMPR2 ϩ/Ϫ mice exhibited increased contractile responses to serotonin mediated by both 5-HT 2 and 5-HT 1 receptors. Furthermore, pulmonary artery smooth muscle cells from BMPR2 ϩ/Ϫ mice exhibited a heightened DNA synthesis and activation of extracellular signal-regulated kinase 1/2 in response to serotonin compared with wild-type cells. In vitro and in vivo experiments suggested that serotonin inhibits BMP signaling via Smad proteins and the expression of BMP responsive genes. These findings provide the first evidence for an interaction between BMPR-II-mediated signaling and the serotonin pathway, perturbation of which may be critical to the pathogenesis of PAH. Key Words: pulmonary arterial hypertension Ⅲ bone morphogenetic protein Ⅲ serotonin I diopathic pulmonary arterial hypertension (IPAH) is characterized by narrowing and obliteration of the small arteries of the lung leading to increased pulmonary vascular resistance. 1 Elevation of pulmonary arterial pressure leads to right ventricular failure. Patients present with dyspnea after exertion, and many died of right heart failure within 3 years of diagnosis, before modern therapies. 2 Treatment with prostanoids or endothelin receptor antagonists improves symptoms and survival, although, for many, the long-term outlook remains poor.Heterozygous germline mutations in the gene encoding the bone morphogenetic protein type II receptor (BMPR-II) occur in up to 70% of cases of familial PAH (FPAH). 3,4 Similar mutations were found in up to 26% of cases of idiopathic PAH. 5 However, the low disease gene penetrance suggests that other genetic or environmental factors are necessary to manifest clinical disease.A series of studies have implicated serotonin (or 5-HT) as a key mediator of PAH. 6 -8 For example, treatment of rats with serotonin potentiates the effects of hypoxia on pulmonary arterial pressure, right ventricular hypertrophy an...

Mutations of the BMPR2 gene predispose to pulmonary arterial hypertension (PAH), a serious, progressive disease of the pulmonary vascular system. However, despite the fact that most PAH families are consistent with linkage to the BMPR2 locus, sequencing only identifies mutations in some 55% of familial cases and between 10% and 40% of cases without a family history (idiopathic or IPAH). We therefore conducted a systematic analysis for larger gene rearrangements in panels of both familial and idiopathic PAH cases that were negative on sequencing of coding regions. Analysis of exon dosage across the entire gene using Multiplex Ligation-dependent Probe Amplification identified nine novel rearrangements and enabled full characterization at the exon level of previously reported deletions. Overall, BMPR2 rearrangements were identified in 7 of 58 families and 6 of 126 IPAH cases, suggesting that gross rearrangements underlie around 12% of all FPAH cases and 5% of IPAH. Importantly, two deletions encompassed all functional protein domains and are predicted to result in null mutations, providing the strongest support yet that the predominant molecular mechanism for disease predisposition is haploinsufficiency. Dosage analysis should now be considered an integral of part of the molecular work-up of PAH patients.

Mesenchymal stem cells (MSCs) are non-hematopoietic progenitor cells, which can be isolated from different types of tissues including bone marrow, adipose tissue, tooth pulp, and placenta/umbilical cord blood. There isolation from adult tissues circumvents the ethical concerns of working with embryonic or fetal stem cells, whilst still providing cells capable of differentiating into various cell lineages, such as adipocytes, osteocytes and chondrocytes. An important feature of MSCs is the low immunogenicity due to the lack of co-stimulatory molecules expression, meaning there is no need for immunosuppression during allogenic transplantation. The tropism of MSCs to damaged tissues and tumor sites makes them a promising vector for therapeutic agent delivery to tumors and metastatic niches. MSCs can be genetically modified by virus vectors to encode tumor suppressor genes, immunomodulating cytokines and their combinations, other therapeutic approaches include MSCs priming/loading with chemotherapeutic drugs or nanoparticles. MSCs derived membrane microvesicles (MVs), which play an important role in intercellular communication, are also considered as a new therapeutic agent and drug delivery vector. Recruited by the tumor, MSCs can exhibit both pro- and anti-oncogenic properties. In this regard, for the development of new methods for cancer therapy using MSCs, a deeper understanding of the molecular and cellular interactions between MSCs and the tumor microenvironment is necessary. In this review, we discuss MSC and tumor interaction mechanisms and review the new therapeutic strategies using MSCs and MSCs derived MVs for cancer treatment.

Extracellular vesicles (EVs) are released by all cells within the tumor microenvironment, such as endothelial cells, tumor-associated fibroblasts, pericytes, and immune system cells. The EVs carry the cargo of parental cells formed of proteins and nucleic acids, which can convey cell-to-cell communication influencing the maintenance and spread of the malignant neoplasm, for example, promoting angiogenesis, tumor cell invasion, and immune escape. However, EVs can also suppress tumor progression, either by the direct influence of the protein and nucleic acid cargo of the EVs or via antigen presentation to immune cells as tumor-derived EVs carry on their surface some of the same antigens as the donor cells. Moreover, dendritic cell-derived EVs carry major histocompatibility complex class I and class II/peptide complexes and are able to prime other immune system cell types and activate an antitumor immune response. Given the relative longevity of vesicles within the circulation and their ability to cross blood–brain barriers, modification of these unique organelles offers the potential to create new biological-tools for cancer therapy. This review examines how modification of the EV cargo has the potential to target specific tumor mechanisms responsible for tumor formation and progression to develop new therapeutic strategies and to increase the efficacy of antitumor therapies.

Planarian flatworms are able to both regenerate their whole bodies and continuously adapt their size to nutrient status. Tight control of stem cell proliferation and differentiation during these processes is the key feature of planarian biology. Here we show that the planarian homolog of the phosphoinositide 3-kinase-related kinase (PIKK) family member SMG-1 and mTOR complex 1 components are required for this tight control. Loss of smg-1 results in a hyper-responsiveness to injury and growth and the formation of regenerative blastemas that remain undifferentiated and that lead to lethal ectopic outgrowths. Invasive stem cell hyper-proliferation, hyperplasia, hypertrophy, and differentiation defects are hallmarks of this uncontrolled growth. These data imply a previously unappreciated and novel physiological function for this PIKK family member. In contrast we found that planarian members of the mTOR complex 1, tor and raptor, are required for the initial response to injury and blastema formation. Double smg-1 RNAi experiments with tor or raptor show that abnormal growth requires mTOR signalling. We also found that the macrolide rapamycin, a natural compound inhibitor of mTORC1, is able to increase the survival rate of smg-1 RNAi animals by decreasing cell proliferation. Our findings support a model where Smg-1 acts as a novel regulator of both the response to injury and growth control mechanisms. Our data suggest the possibility that this may be by suppressing mTOR signalling. Characterisation of both the planarian mTORC1 signalling components and another PIKK family member as key regulators of regeneration and growth will influence future work on regeneration, growth control, and the development of anti-cancer therapies that target mTOR signalling.

There are three prolyl hydroxylases (PHD1, 2 and 3) that regulate the hypoxia-inducible factors (HIFs), the master transcriptional regulators that respond to changes in intracellular O(2) tension. In high O(2) tension (normoxia) the PHDs hydroxylate two conserved proline residues on HIF-1α, which leads to binding of the von Hippel-Lindau (VHL) tumour suppressor, the recognition component of a ubiquitin-ligase complex, initiating HIF-1α ubiquitylation and degradation. However, it is not known whether PHDs and VHL act separately to exert their enzymatic activities on HIF-1α or as a multiprotein complex. Here we show that the tumour suppressor protein LIMD1 (LIM domain-containing protein) acts as a molecular scaffold, simultaneously binding the PHDs and VHL, thereby assembling a PHD-LIMD1-VHL protein complex and creating an enzymatic niche that enables efficient degradation of HIF-1α. Depletion of endogenous LIMD1 increases HIF-1α levels and transcriptional activity in both normoxia and hypoxia. Conversely, LIMD1 expression downregulates HIF-1 transcriptional activity in a manner depending on PHD and 26S proteasome activities. LIMD1 family member proteins Ajuba and WTIP also bind to VHL and PHDs 1 and 3, indicating that these LIM domain-containing proteins represent a previously unrecognized group of hypoxic regulators.