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Genome-wide association studies (GWASs) for osteoporotic traits have identified over 1000 associations; however, their impact has been limited by the difficulties of causal gene identification and a strict focus on bone mineral density (BMD). Here, we use Diversity Outbred (DO) mice to directly address these limitations by performing a systems genetics analysis of 55 complex skeletal phenotypes. We apply a network approach to cortical bone RNA-seq data to discover 66 genes likely to be causal for human BMD GWAS associations, including the genes SERTAD4 and GLT8D2. We also perform GWAS in the DO for a wide-range of bone traits and identify Qsox1 as a gene influencing cortical bone accrual and bone strength. In this work, we advance our understanding of the genetics of osteoporosis and highlight the ability of the mouse to inform human genetics., Osteoporosis GWAS faces two challenges, causal gene discovery and a lack of phenotypic diversity. Here, the authors use the Diversity Outbred mouse population to inform human GWAS using networks and map genetic loci for 55 bone traits, identifying new potential bone strength genes.

Gene fusions and their products (RNA and protein) have been traditionally recognized as unique features of cancer cells and are used as ideal biomarkers and drug targets for multiple cancer types. However, recent studies have demonstrated that chimeric RNAs generated by intergenic alternative splicing can also be found in normal cells and tissues. In this study, we aim to identify chimeric RNAs in different non-neoplastic cell lines and investigate the landscape and expression of these novel candidate chimeric RNAs. To do so, we used HEK-293T, HUVEC, and LO2 cell lines as models, performed paired-end RNA sequencing, and conducted analyses for chimeric RNA profiles. Several filtering criteria were applied, and the landscape of chimeric RNAs was characterized at multiple levels and from various angles. Further, we experimentally validated 17 chimeric RNAs from different classifications. Finally, we examined a number of validated chimeric RNAs in different cancer and non-cancer cells, including blood from healthy donors, and demonstrated their ubiquitous expression pattern.

Genome-wide association studies (GWASs) for osteoporotic traits have identified over 1000 associations; however, their impact has been limited by the difficulties of causal gene identification and a strict focus on bone mineral density (BMD). Here, we used Diversity Outbred (DO) mice to directly address these limitations by performing the first systems genetics analysis of 55 complex skeletal phenotypes. We applied a network approach to cortical bone RNA-seq data to discover 72 genes likely to be causal for human BMD GWAS associations, including the novel genes SERTAD4 and GLT8D2. We also performed GWAS in the DO for a wide-range of bone traits and identified Qsox1 as a novel gene influencing cortical bone accrual and bone strength. Our results provide a new perspective on the genetics of osteoporosis and highlight the ability of the mouse to inform human genetics.

Background Microvascular dysfunction is a major complication in hypertensive patients. We previously reported that CD4+CD25+ T regulatory cells (Treg) play an important preventive role in hypertension-induced vascular dysfunction. However, whether Treg cells therapy and autophagy inhibition could rescue Treg cells survival and microvascular function in established hypertension is an important question that remained unanswered. Methods & results Here we showed that Treg cells from mice model of established hypertension displayed an enhanced apoptotic rate, which was rescued with Treg cells transfer and autophagy inhibition. We also showed increased autophagy in mesenteric resistance artery (MRA) in mice with established hypertension. Importantly, the inhibition of autophagy or one single transfer of Treg cells into mice with established hypertension improved the microvascular function independently of high blood pressure. The protection involves the modulation of interleukin-10 (IL-10), inflammation, endoplasmic reticulum (ER) stress, oxidative stress, Akt, and eNOS. Conclusions The present study suggests that Treg cells survival is regulated by autophagy. Also, Treg cells as a cellular therapy aimed at rescuing the microvascular function through an autophagy-dependent mechanism and independently of arterial blood pressure lowering effects. Because our mouse model of established hypertension mimics the clinical situation, our results have the potential for new therapeutic approaches that involve the manipulation of Treg cells and autophagy to overcome established hypertension-induced cardiovascular complications.

Objectives Stromal interacting molecule-1 (STIM1) plays a role in coordinating calcium signaling in different cell types. The increase or deletion of STIM1 expression in cardiomyocyte causes cardiac complication. Moreover, the deletion of STIM1 in endothelial cell causes vascular endothelial dysfunction. However, the disruption of STIM1 in smooth muscle cells (SMC) has no effect on endothelial function but protects vascular function when mice are infused with angiotensin-II. Nevertheless, the role of SMC-STIM1 in acute and chronic myocardial infarction (MI) induced by acute ischemia-reperfusion injury and permanent coronary artery occlusion is unknown. Methods and results Stim1 were generated and crossed into the SM22α-Cre backgrounds. SM22α-Cre causes deletion of STIM1 floxed genes in adult SMC (Stim1). Control and Stim1 mice were subjected to acute ischemia-reperfusion injury. Hearts were then harvested and incubated with triphenyltetrazolium chloride to determine the infarct size. In control mice which are subjected to ischemia-reperfusion, the heart developed a significant infarct associated with an increase in STIM1 expression. Interestingly, the infarct size was substantially reduced in Stim1 mice. The protection in Stim1 mice against ischemia-reperfusion injury involves the modulation of endoplasmic reticulum stress, apoptosis, oxidative stress, protein kinase B, and mitogen-activated protein (MAP) kinase (ERK1/2 and p38) signaling, and inflammation. Furthermore, in another model of chronic MI induced by permanent coronary artery occlusion, SMC-STIM1 disruption significantly reduced myocardial infarct size and improved cardiac function. Conclusion Our results provide new evidence that SMC-STIM1 disruption is a novel mechanism that protects the heart from MI through reduction of endoplasmic reticulum stress, oxidative stress, MAP-Kinase, apoptosis, and inflammation.

We previously reported that EGFR tyrosine kinase (EGFRtk) activity and endoplasmic reticulum (ER) stress are enhanced in type 2 diabetic (T2D) mice and cause vascular dysfunction. In the present study, we determined the in vivo contribution of EGFRtk and ER stress in acute myocardial infarction induced by acute ischemia (40 min)-reperfusion (24 h) (I/R) injury in T2D (db−/db−) mice. We treated db−/db− mice with EGFRtk inhibitor (AG1478, 10 mg/kg/day) for 2 weeks. Mice were then subjected to myocardial I/R injury. The db−/db− mice developed a significant infarct after I/R injury. The inhibition of EGFRtk significantly reduced the infarct size and ER stress induction. We also determined that the inhibition of ER stress (tauroursodeoxycholic acid, TUDCA, 150 mg/kg per day) in db−/db− significantly decrease the infarct size indicating that ER stress is a downstream mechanism to EGFRtk. Moreover, AG1478 and TUDCA reduced myocardium p38 and ERK1/2 MAP-kinases activity, and increased the activity of the pro-survival signaling cascade Akt. Additionally, the inhibition of EGFRtk and ER stress reduced cell apoptosis and the inflammation as indicated by the reduction in macrophages and neutrophil infiltration. We determined for the first time that the inhibition of EGFRtk protects T2D heart against I/R injury through ER stress-dependent mechanism. The cardioprotective effect of EGFRtk and ER stress inhibition involves the activation of survival pathway, and inhibition of apoptosis, and inflammation. Thus, targeting EGFRtk and ER stress has the potential for therapy to overcome myocardial infarction in T2D.

Objectives— Chronic hypertension is the most critical risk factor for cardiovascular disease, heart failure, and stroke. Approach and Results— Here we show that wild-type mice infused with angiotensin II develop hypertension, cardiac hypertrophy, perivascular fibrosis, and endothelial dysfunction with enhanced stromal interaction molecule 1 (STIM1) expression in heart and vessels. All these pathologies were significantly blunted in mice lacking STIM1 specifically in smooth muscle (Stim1 SMC−/− ). Mechanistically, STIM1 upregulation during angiotensin II–induced hypertension was associated with enhanced endoplasmic reticulum stress, and smooth muscle STIM1 was required for endoplasmic reticulum stress–induced vascular dysfunction through transforming growth factor-β and nicotinamide adenine dinucleotide phosphate oxidase–dependent pathways. Accordingly, knockout mice for the endoplasmic reticulum stress proapoptotic transcriptional factor, CCAAT-enhancer–binding protein homologous protein (CHOP −/− ), were resistant to hypertension-induced cardiovascular pathologies. Wild-type mice infused with angiotensin II, but not Stim1 SMC−/− or CHOP −/− mice showed elevated vascular nicotinamide adenine dinucleotide phosphate oxidase activity and reduced phosphorylated endothelial nitric oxide synthase, cGMP, and nitrite levels. Conclusions— Thus, smooth muscle STIM1 plays a crucial role in the development of hypertension and associated cardiovascular pathologies and represents a promising target for cardiovascular therapy.

Background: Stromal interacting molecule 1 (STIM1) is a calcium sensor in the endoplasmic reticulum (ER). We previously reported that STIM1 plays opposing roles in vascular smooth muscle cells (SMC) vs. endothelial cell in the regulation of vascular reactivity. However, the role of SMC STIM1 in heart failure is yet to be determined. Methods and Results: We utilize control (C57/Bl6) and mice lacking STIM1 specifically in SMC (Stim1 SMC-/- ). We subjected all mice to left anterior descending coronary artery (LAD) permanent occlusion for 3 weeks. We performed echocardiography before the LAD ligation and 3 week after. In the end, we sacrificed mice and harvested the heart for biochemical and histology studies. The heart weight, collagen, and infarct area were significantly augmented in control mice subjected to LAD occlusion. The diastolic (Ejection fraction) and systolic functions (fractional shortening) were significantly compromised in control mice subjected to LAD occlusion. Interestingly, the cardiac hypertrophy, the collagen content, the infarct area, the ejection fraction, and the fraction shortening were protected in Stim1 SMC-/- mice subjected to LAD occlusion. The protective effect of STIM1 disruption in SMC involved the reduction in ER stress activation, the autophagy, and apoptosis mechanisms. Conclusion: Our results indicate that the disruption of STIM1 in SMC protects the heart against chronic ischemia through the inhibition of ER stress, autophagy, and apoptosis.