Tianqing Zhu

RS-1 enhances CRISPR/Cas9- and TALEN-mediated knock-in efficiency.

Zinc-finger nuclease, transcription activator-like effector nuclease and CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9) are becoming major tools for genome editing. Importantly, knock-in in several non-rodent species has been finally achieved thanks to these customizable nucleases; yet the rates remain to be further improved. We hypothesize that inhibiting non-homologous end joining (NHEJ) or enhancing homology-directed repair (HDR) will improve the nuclease-mediated knock-in efficiency. Here we show that the in vitro application of an HDR enhancer, RS-1, increases the knock-in efficiency by two- to five-fold at different loci, whereas NHEJ inhibitor SCR7 has minimal effects. We then apply RS-1 for animal production and have achieved multifold improvement on the knock-in rates as well. Our work presents tools to nuclease-mediated knock-in animal production, and sheds light on improving gene-targeting efficiencies on pluripotent stem cells.

Nitro-Oleic Acid Inhibits Angiotensin II–Induced Hypertension

Rationale Nitro-oleic acid (OA-NO2) is a bioactive, nitric-oxide derived fatty acid with physiologically relevant vasculoprotective properties in vivo. OA-NO2 exerts cell signaling actions as a result of its strong electrophilic nature and mediates pleiotropic cell responses in the vasculature. Objective The present study sought to investigate the protective role of OA-NO2 in angiotensin (Ang) II–induced hypertension. Methods and Results We show that systemic administration of OA-NO2 results in a sustained reduction of Ang II–induced hypertension in mice and exerts a significant blood pressure lowering effect on preexisting hypertension established by Ang II infusion. OA-NO2 significantly inhibits Ang II contractile response as compared to oleic acid (OA) in mesenteric vessels. The improved vasoconstriction is specific for the Ang II type 1 receptor (AT1R)-mediated signaling because vascular contraction by other G-protein–coupled receptors is not altered in response to OA-NO2 treatment. From the mechanistic viewpoint, OA-NO2 lowers Ang II–induced hypertension independently of peroxisome proliferation-activated receptor (PPAR)&ggr; activation. Rather, OA-NO2, but not OA, specifically binds to the AT1R, reduces heterotrimeric G-protein coupling, and inhibits IP3 (inositol-1,4,5-trisphosphate) and calcium mobilization, without inhibiting Ang II binding to the receptor. Conclusions These results demonstrate that OA-NO2 diminishes the pressor response to Ang II and inhibits AT1R-dependent vasoconstriction, revealing OA-NO2 as a novel antagonist of Ang II–induced hypertension.

Altered long non-coding RNA transcriptomic profiles in brain microvascular endothelium after cerebral ischemia

The brain endothelium is an important therapeutic target for the inhibition of cerebrovascular dysfunction in ischemic stroke. Previously, we documented the important regulatory roles of microRNAs in the cerebral vasculature, in particular the cerebral vascular endothelium. However, the functional significance and molecular mechanisms of other classes of non-coding RNAs in the regulation of cerebrovascular endothelial pathophysiology after stroke are completely unknown. Using RNA sequencing (RNA-seq) technology, we profiled long non-coding RNA (lncRNA) expressional signatures in primary brain microvascular endothelial cells (BMECs) after oxygen-glucose deprivation (OGD), an in vitro mimic of ischemic stroke conditions. After 16h of OGD exposure, the expression levels for 362 of the 10,677 lncRNAs analyzed changed significantly, including a total of 147 lncRNAs increased and 70 lncRNAs decreased by more than 2-fold. Among them, the most highly upregulated lncRNAs include Snhg12, Malat1, and lnc-OGD 1006, whereas the most highly downregulated lncRNAs include 281008D09Rik, Peg13, and lnc-OGD 3916. Alteration of the most highly upregulated/downregulated ODG-responsive lncRNAs was further confirmed in cultured BMECs after OGD as well as isolated cerebral microvessels in mice following transient middle cerebral artery occlusion (MCAO) and 24h reperfusion by the quantitative real-time PCR approach. Moreover, promoter analysis of altered ODG-responsive endothelial lncRNA genes by bioinformatics showed substantial transcription factor binding sites on lncRNAs, implying potential transcriptional regulation of those lncRNAs. These findings are the first to identify OGD-responsive brain endothelial lncRNAs, which suggest potential pathological roles for these lncRNAs in mediating endothelial responses to ischemic stimuli. Endothelial-selective lncRNAs may function as a class of novel master regulators in cerebrovascular endothelial pathologies after ischemic stroke.

Hepatic Transmembrane 6 Superfamily Member 2 Regulates Cholesterol Metabolism in Mice.

BACKGROUND & AIMS The rs58542926 C>T variant of the transmembrane 6 superfamily member 2 gene (TM6SF2), encoding an E167K amino acid substitution, has been correlated with reduced total cholesterol (TC) and cardiovascular disease. However, little is known about the role of TM6SF2 in metabolism. We investigated the long-term effects of altered TM6SF2 levels in cholesterol metabolism. METHODS C57BL/6 mice (controls), mice that expressed TM6SF2 specifically in the liver, and mice with CRISPR/Cas9-mediated knockout of Tm6sf2 were fed chow or high-fat diets. Blood samples were collected from all mice and plasma levels of TC, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol, and triglycerides were measured. Liver tissues were collected and analyzed by histology, real-time polymerase chain reaction, and immunoblot assays. Adenovirus vectors were used to express transgenes in cultured Hep3B hepatocytes. RESULTS Liver-specific expression of TM6SF2 increased plasma levels of TC and LDL-c, compared with controls, and altered liver expression of genes that regulate cholesterol metabolism. Tm6sf2-knockout mice had decreased plasma levels of TC and LDL-c, compared with controls, and consistent changes in expression of genes that regulate cholesterol metabolism. Expression of TM6SF2 promoted cholesterol biosynthesis in hepatocytes. CONCLUSIONS TM6SF2 regulates cholesterol metabolism in mice and might be a therapeutic target for cardiovascular disease.

Production of Apolipoprotein C-III Knockout Rabbits using Zinc Finger Nucleases

Apolipoprotein (Apo) C-III (ApoCIII) resides on the surface of plasma chylomicron (CM), very low density lipoprotein (VLDL) and high density lipoproteins (HDL). It has been recognized that high levels of plasma ApoCIII constitutea risk factor for cardiovascular diseases (CVD). Elevated plasma ApoCIII level often correlates with insulin resistance, obesity, and hypertriglyceridemia. Invaluable knowledge on the roles of ApoCIIIin lipid metabolisms and CVD has been obtained from transgenic mouse models including ApoCIII knockout (KO) mice; however, it is noted that the metabolism of lipoprotein in mice is different from that of humans in many aspects. It is not known until now whether elevated plasma ApoCIII is directly atherogenic. We worked to develop ApoCIII KO rabbits in the present study based on the hypothesis that rabbits can serve as a reasonablemodelfor studying human lipid metabolism and atherosclerosis. Zinc finger nuclease (ZFN) sets targeting rabbit ApoCIIIgene were subjected to in vitro validation prior to embryo microinjection. The mRNA was injected to the cytoplasm of 35 rabbit pronuclear stage embryos, and evaluated the mutation rates at the blastocyst state. Of sixteen blastocysts that were assayed, a satisfactory 50% mutation rate (8/16) at the targeting site was achieved, supporting the use of Set 1 for in vivo experiments. Next, we microinjected 145 embryos with Set 1 mRNA, and transferred these embryos to 7 recipient rabbits. After 30 days gestation, 21 kits were born, out of which five were confirmed as ApoCIII KO rabbits after PCR sequencing assays. The KO animal rate (#KO kits/total born) was 23.8%. The overall production efficiency is 3.4% (5 kits/145 embryos transferred). The present work demonstrated that ZFN is a highly efficient method to produce KO rabbits. These ApoCIII KO rabbits are novel resources to study the roles of ApoCIII in lipid metabolisms.

Identification and characterization of rabbit ROSA26 for gene knock-in and stable reporter gene expression

The laboratory rabbit has been a valuable model system for human disease studies. To make the rabbit model more amendable to targeted gene knockin and stable gene over-expression, we identified a rabbit orthologue of the mouse Rosa26 locus through genomic sequence homology analysis. Real-time PCR and 5′ RACE and 3′ RACE experiments revealed that this locus encodes two transcript variants of a long noncoding RNA (lncRNA) (rbRosaV1 and rbRosaV2). Both variants are expressed ubiquitously and stably in different tissues. We next targeted the rabbit Rosa26 (rbRosa26) locus using CRISPR/Cas9 and produced two lines of knock-in rabbits (rbRosa26-EGFP, and rbRosa26-Cre-reporter). In both lines, all the founders and their offspring appear healthy and reproduce normally. In F1 generation animals, the rbRosa26-EGFP rabbits express EGFP, and the rbRosa26-Cre-reporter rabbits express tdTomato ubiquitously in all the tissues examined. Furthermore, disruption of rbRosa26 locus does not adversely impact the animal health and reproduction. Therefore, our work establishes rbRosa26 as a safe harbor suitable for nuclease mediated gene targeting. The addition of rbRosa26 to the tool box of transgenic research is expected to allow diverse genetic manipulations, including gain-of function, conditional knock out and lineage-tracing studies in rabbits.

TFEB inhibits endothelial cell inflammation and reduces atherosclerosis.

TFEB suppresses oxidative stress and inflammation in endothelial cells to decrease atherosclerosis. Protected from atherosclerosis by TFEB Atherosclerosis, or the buildup of fatty plaques in blood vessels, can lead to high blood pressure and heart attacks. Lu et al. found that, in cultured endothelial cells, the transcription factor TFEB reduced oxidative stress and inflammation, two processes thought to contribute to the development of atherosclerosis. When fed a high-fat diet, mice that overexpressed TFEB in endothelial cells developed smaller atherosclerotic lesions than their control littermates on the same diet. Thus, treatments that enhance the activity of TFEB in endothelial cells could reduce the development of atherosclerosis. Furthermore, because the anti-inflammatory effect of TFEB in endothelial cells was independent of its role in autophagy, a process in which cells digest macromolecules and organelles, these results highlight new roles for this transcription factor. Transcription factor EB (TFEB) is a master regulator of autophagy and lysosome biogenesis. We investigated the function of TFEB in vascular biology and pathophysiology and demonstrated that TFEB in endothelial cells inhibited inflammation and reduced atherosclerosis development. Laminar shear stress, which protects against atherosclerosis, increased TFEB abundance in cultured primary human endothelial cells. Furthermore, TFEB overexpression in these cells was anti-inflammatory, whereas TFEB knockdown aggravated inflammation. The anti-inflammatory effect of TFEB was, at least, partially due to reduced oxidative stress because TFEB overexpression in endothelial cells decreased the concentrations of reactive oxygen species and increased the expression of the antioxidant genes HO1 (which encodes heme oxygenase 1) and SOD2 (which encodes superoxide dismutase 2). In addition, transgenic mice with endothelial cell–specific expression of TFEB exhibited reduced leukocyte recruitment to endothelial cells and decreased atherosclerosis development. Our study suggests that TFEB is a protective transcription factor against endothelial cell inflammation and a potential target for treating atherosclerosis and associated cardiovascular diseases.

Hyperlipidemia-associated gene variations and expression patterns revealed by whole-genome and transcriptome sequencing of rabbit models.

The rabbit (Oryctolagus cuniculus) is an important experimental animal for studying human diseases, such as hypercholesterolemia and atherosclerosis. Despite this, genetic information and RNA expression profiling of laboratory rabbits are lacking. Here, we characterized the whole-genome variants of three breeds of the most popular experimental rabbits, New Zealand White (NZW), Japanese White (JW) and Watanabe heritable hyperlipidemic (WHHL) rabbits. Although the genetic diversity of WHHL rabbits was relatively low, they accumulated a large proportion of high-frequency deleterious mutations due to the small population size. Some of the deleterious mutations were associated with the pathophysiology of WHHL rabbits in addition to the LDLR deficiency. Furthermore, we conducted transcriptome sequencing of different organs of both WHHL and cholesterol-rich diet (Chol)-fed NZW rabbits. We found that gene expression profiles of the two rabbit models were essentially similar in the aorta, even though they exhibited different types of hypercholesterolemia. In contrast, Chol-fed rabbits, but not WHHL rabbits, exhibited pronounced inflammatory responses and abnormal lipid metabolism in the liver. These results provide valuable insights into identifying therapeutic targets of hypercholesterolemia and atherosclerosis with rabbit models.

A Tripeptide Diapin Effectively Lowers Blood Glucose Levels in Male Type 2 Diabetes Mice by Increasing Blood Levels of Insulin and GLP-1

The prevalence of type 2 diabetes (T2D) is rapidly increasing worldwide. Effective therapies, such as insulin and Glucagon-like peptide-1 (GLP-1), require injections, which are costly and result in less patient compliance. Here, we report the identification of a tripeptide with significant potential to treat T2D. The peptide, referred to as Diapin, is comprised of three natural L-amino acids, GlyGlyLeu. Glucose tolerance tests showed that oral administration of Diapin effectively lowered blood glucose after oral glucose loading in both normal C57BL/6J mice and T2D mouse models, including KKay, db/db, ob/ob mice, and high fat diet-induced obesity/T2D mice. In addition, Diapin treatment significantly reduced casual blood glucose in KKay diabetic mice in a time-dependent manner without causing hypoglycemia. Furthermore, we found that plasma GLP-1 and insulin levels in diabetic models were significantly increased with Diapin treatment compared to that in the controls. In summary, our findings establish that a peptide with minimum of three amino acids can improve glucose homeostasis and Diapin shows promise as a novel pharmaceutical agent to treat patients with T2D through its dual effects on GLP-1 and insulin secretion.

Yes‐Associated Protein Inhibits Transcription of Myocardin and Attenuates Differentiation of Vascular Smooth Muscle Cell from Cardiovascular Progenitor Cell Lineage

Vascular smooth muscle cells (VSMCs) derived from cardiovascular progenitor cell (CVPC) lineage populate the tunica media of the aortic root. Understanding differentiation of VSMCs from CVPC will further our understanding of the molecular mechanisms contributing to aortic root aneurysms, and thus, facilitate the development of novel therapeutic agents to prevent this devastating complication. It is established that the yes‐associated protein (YAP) and Hippo pathway is important for VSMC proliferation and phenotype switch. To determine the role of YAP in differentiation of VSMCs from CVPCs, we utilized the in vitro monolayer lineage specific differentiation method by differentiating human embryonic stem cells into CVPCs, and then, into VSMCs. We found that expression of YAP decreased during differentiation of VSMC from CVPCs. Overexpression of YAP attenuated expression of VSMC contractile markers and impaired VSMC function. Knockdown of YAP increased expression of contractile proteins during CVPC‐VSMCs differentiation. Importantly, expression of YAP decreased transcription of myocardin during this process. Overexpression of YAP in PAC1 SMC cell line inhibited luciferase activity of myocardin proximal promoter in a dose dependent and NKX2.5 dependent manners. YAP protein interacted with NKX2.5 protein and inhibited binding of NKX2.5 to the 5′‐proximal promoter region of myocardin in CVPC‐derived VSMCs. In conclusion, YAP negatively regulates differentiation of VSMCs from CVPCs by decreasing transcription of myocardin in a NKX2.5‐dependent manner. Stem Cells 2017;35:351–361