An optimized prime editing system for efficient modification of the pig genome

Prime editing (PE) is a recent gene editing technology that can mediate insertions or deletions and all twelve types of base-to-base conversions. However, its low efficiency hampers the application in creating novel breeds and biomedical models, especially in pigs and other important farm animals. Here, we demonstrate that the pig genome is editable using the PE system, but the editing efficiency was quite low as expected. Therefore, we aimed to enhance PE efficiency by modulating both exogenous PE tools and endogenous pathways in porcine embryonic fibroblasts (PEFs). First, we modified the pegRNA by extending the duplex length and mutating the fourth thymine in a continuous sequence of thymine bases to cytosine, which significantly enhanced PE efficiency by improving the expression of pegRNA and targeted cleavage. Then, we targeted SAMHD1, a deoxynucleoside triphosphate triphosphohydrolase (dNTPase) that impedes the reverse transcription process in retroviruses, and found that treatment with its inhibitor, cephalosporin C zinc salt (CPC), increased PE efficiency up to 29-fold (4-fold on average), presumably by improving the reverse transcription process of Moloney murine leukemia virus reverse transcriptase (M-MLV RT) in the PE system. Moreover, PE efficiency was obviously improved by treatment with a panel of histone deacetylase inhibitors (HDACis). Among the four HDACis tested, panobinostat was the most efficient, with an efficiency up to 122-fold (7-fold on average), partly due to the considerable HDACi-mediated increase in transgene expression. In addition, the synergistic use of the three strategies further enhanced PE efficiency in PEFs. Our study provides novel approaches for optimization of the PE system and broadens the application scope of PE in agriculture and biomedicine.

Sodium MRI at 7T for Early Response Evaluation of Intracranial Tumors following Stereotactic Radiotherapy Using the CyberKnife

BACKGROUND AND PURPOSE

Conventionally, early treatment response to stereotactic radiotherapy in intracranial tumors is often determined by structural MR imaging. Tissue sodium concentration is altered by cellular integrity and energy status in cells. In this study, we aimed to investigate the feasibility of sodium MR imaging at 7T for the preliminary evaluation of radiotherapeutic efficacy for intracranial tumors.

MATERIALS AND METHODS

Data were collected from 16 patients (12 men and 4 women, 24-75 years of age) with 22 intracranial tumors who were treated with stereotactic radiation therapy using CyberKnife at our institution between December 1, 2016, and August 15, 2019. Sodium MR imaging was performed at 7T before and 48 hours, 1 week, and 1 month after CyberKnife radiation therapy. Tissue sodium concentration (TSC) was calculated and analyzed based on manually labeled regions of tumors.

RESULTS

Ultra-high-field sodium MR imaging clearly showed the intratumoral signal, which is significantly higher than that of normal tissue (t = 5.250, P <.001)., but the edema zone has some influence. The average TSC ratios of tumor to CSF in the 22 tumors, contralateral normal tissues, edema zones, frontal cortex, and frontal white matter were 0.66 (range, 0.23-1.5), 0.30 (range, 0.15-0.43), 0.58 (range, 0.25-1.21), 0.25 (range, 0.17-0.42), and 0.30 (range, 0.19-0.49), respectively. A total of 12 tumors in 8 patients were scanned at 48 hours, 1 week, and 1 month after treatment. The average TSC at 48 hours after treatment was 0.06 higher than that before treatment and began to decrease at 1 week. The TSC ratios of 10 continued to decline and 2 tumors increased at 1 month, respectively. Tumor volume decreased by 2.4%-99% after 3 months.

CONCLUSIONS

Changes in the TSC can be quantified by sodium MR imaging at 7T and used to detect radiobiologic alterations in intracranial tumors at early time points after CyberKnife radiation therapy.

MicroRNA 4651 regulates nonsense-mediated mRNA decay by targeting SMG9 mRNA

Nonsense-mediated mRNA decay (NMD) is originally identified as a conserved RNA surveillance mechanism that rapidly degrades aberrant mRNA containing premature termination codons (PTCs). However, the molecular regulation mechanisms by which microRNAs inhibit NMD has not been well understood. Here we identified that miR-4651 participated in the NMD pathway by downregulating expression levels of SMG9. We provided evidences that (1) Overexpression of miR-4651 mimic significantly inhibited the expression of SMG9 (P < 0.05); (2) NMD substrates genes, TBL2 and GADD45B were both increased at mRNA and protein expression levels when SMG9 was suppressed by siRNA, whereas decreased by SMG9 overexpression; (3) Expression of SMG9 was significantly increased but TBL2, GADD45B were significantly decreased when cells transfected with miR-4651 inhibitor (P < 0.05). These results indicated that miR-4651 regulated NMD by targeting SMG9 mRNA. Our study highlights that miR-4651 represses NMD. miR-4651 targets SMG9 and represses the expression levels of SMG9. NMD activity is decreased additionally when SMG9 is inhibited. The present study provides evidence for microRNA/NMD regulatory mechanism.

[Treatment of single one-stage posterior atlantoaxial fixation in Chiari malformation]

Objective: To explore the effects of surgical technique of single one-stage posterior C(1-2) screw rod fixation of Chiari malformation (CM) associated with occipitalization and without atlantoaxial dislocation. Methods: A total of 23 patients with CM treated between January 2014 and October 2015 in Department of Neurosurgery of Chinese People's Liberation Army General Hospital were retrospective reviewed. All of them were diagnosis with CM associated with occipitalization and without atlantoaxial dislocation, including 8 males and 15 females, aging from 11 to 57 years (mean (35.5±10.52) years). Single one-stage posterior C(1-2) screw rod fixation with bone grafting fusion was performed. Operation time and intraoperative blood loss were recorded. Japanese Orthopaedic Association (JOA) scores and Odom rating were used to evaluate the clinical effects at pre- and post-operative. Regression of the cerebellar tonsillar was measured by MRI. The results were analyzed by paired samples t test. Results: Twenty-three patients were implanted screws successfully, the vertebral artery injury and cerebrospinal fluid leakage were not found. The mean operation time was (172.7±19.9) minutes, the intraoperative blood loss was (153.9±49.3) ml. Compared to preoperative, the JOA score increased (13.7±1.6 vs. 11.5±1.4) and the tonsillar herniation decreased ((0.8±0.6)cm vs. (1.9±0.6) cm) in the last follow-up, there were statistical difference (t=13.386, P<0.01; t=17.995, P<0.01). The results of the postoperative Odom grading were as follows: 6 cases were perfect (26.1%), 13 cases were good (56.5%), 4 cases were moderate (17.4%) and no case was poor.No signs of instrument loosen or screw broken was noticed. 100% bony fusion rate was achieved. The follow-up time was 6 to 23 months (mean (10.5±3.2) months). One case developed internal fixator related discomfort, the symptom was relieved by internal fixator removal surgery performed 4 months after the operation when osseous fusion had already been achieved. No new neurologic symptoms were observed in other 22 patients. Conclusions: The results of the study substantiates the effectiveness of single one-stage posterior fixation strategy for CM, which is associated with occipitalization and without atlantoaxial dislocation. This technique could be an alternative choice for this type of CM.

[Copy number variants analysis in whole-genome of patients with lipoma tethered cord syndrome]

Objective: To explore the abnormality of chromosomes of patients with lipoma tethered cord syndrome and the probable association between Copy Number Variations (CNV) and lipoma tethered cord syndrome. Methods: By using the Agilent SurePrint G3 Human CGH 8×60K Microarray Kit, we performed genome-wide screening for CNV on 11 patients with lipoma tethered cord syndrome adopted by the Neurosurgery Department of Chinese PLA General Hospital and their healthy parents from March 2015 to May 2015. We analyze CNVs got by the kit against the gene databases. Unrelated confirmed polymorphisms contained in Database of Genomic Variants (DGV) were discarded. Database of Chromosomal Imbalance and Phenotype in Humans using Ensemble Resources (DECIPHER) helps us with similarity inquiry, and UCSC Genome Browser helps in identification of non-polymorphic CNV. Biological process, cellular component and molecular function enrichment of these genes were conducted to confirm the association between the CNV and lipoma tethered cord syndrome. Results: 17 CNV were discovered by aCGH in 11 patients. Chr8: 39258894-39386158 and Chr15: 20481702-22509254 showed a high frequency of 5/11. Angelman syndrome and Prader-Wolli syndrome were found to be associated with the CNV of Chr15. Gene function enrichment analysis revealed that ADAM5P and ADAM3A contained in CNV obtained from patients with lipoma tethered cord syndrome was also associated with orofacial clefts. Conclusions: CNV in Chr8 and Chr15 of patients with lipoma tethered cord syndrome had a higher frequency than that of common human. It revealed that there is probable association between these two pieces of CNV and lipoma tethered cord syndrome. To explorer related genes or CNV, focusing on certain type of NTDs may increase the research efficiency and get more accurate results.

Radiosynthesis of [18F] N-(3-Fluoropropyl)-2-β-Carbomethoxy-3-β-(4-Bromophenyl) Nortropane and the regional brain uptake in non human primate using PET

A synthetic procedure for the preparation of [18F]FPCBT, an imaging agent for the dopamine transporter (DAT), has been developed. The radiosynthesis was carried out in a two step procedure. Even though the yield was low, we were able to prepare 20 to 30 mCi of the product, which was enough for two or three studies. The radiochemical purity was greater than 96%. The in vivo properties of this radiotracer were evaluated using baboon and it showed highest uptake in the striatum. The studies also revealed that the maximum uptake was reached within 7 to 10 minutes post injection. Plasma metabolite analysis indicated that there is only one metabolite and it is less lipophilic than the parent compound. [18F]FPCBT displayed good brain uptake and its high target to non target ratio indicate that it is a potential candidate for DAT imaging.

Synthesis and biological evaluation of a series of novel N- or O-fluoroalkyl derivatives of tropane: potential positron emission tomography (PET) imaging agents for the dopamine transporter

A series of novel fluoroalkyl-containing tropane derivatives was synthesized, and their binding affinities for the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET) were determined via competitive binding assays. Among these derivatives, the fluoropropyl ester of beta-CIT (19), the fluoroethyl ester of beta-CIT (20), the N-fluoropropyl derivative of beta-CBT (12), and the fluoropropyl ester of beta-CMT (18) displayed higher affinity and greater selectivity for the DAT versus SERT and NET than FP-CIT, which indicates that they are attractive candidates for the development of (18)F-labeled PET imaging agents for the DAT.

Synthesis and opioid receptor affinity of morphinan and benzomorphan derivatives: mixed kappa agonists and mu agonists/antagonists as potential pharmacotherapeutics for cocaine dependence

This report concerns the synthesis and preliminary pharmacological evaluation of a novel series of kappa agonists related to the morphinan (-)-cyclorphan (3a) and the benzomorphan (-)-cyclazocine (2) as potential agents for the pharmacotherapy of cocaine abuse. Recent evidence suggests that agonists acting at kappa opioid receptors may modulate the activity of dopaminergic neurons and alter the neurochemical and behavioral effects of cocaine. We describe the synthesis and chemical characterization of a series of morphinans 3a-c, structural analogues of cyclorphan [(-)-3-hydroxy-N-cyclopropylmethylmorphinan S(+)-mandelate, 3a], the 10-ketomorphinans 4a,b, and the 8-ketobenzomorphan 1b. Binding experiments demonstrated that the cyclobutyl analogue 3b [(-)-3-hydroxy-N-cyclobutylmethylmorphinan S(+)-mandelate, 3b, MCL-101] of cyclorphan (3a) had a high affinity for mu, delta, and kappa opioid receptors in guinea pig brain membranes. Both 3a,b were approximately 2-fold more selective for the kappa receptor than for the mu receptor. However 3b (the cyclobutyl analogue) was 18-fold more selective for the kappa receptor in comparison to the delta receptor, while cyclorphan (3a) had only 4-fold greater affinity for the kappa receptor in comparison to the delta receptor. These findings were confirmed in the antinociceptive tests (tail-flick and acetic acid writhing) in mice, which demonstrated that cyclorphan (3a) produced antinociception that was mediated by the delta receptor while 3b did not produce agonist or antagonist effects at the delta receptor. Both 3a,b had comparable kappa agonist properties. 3a,b had opposing effects at the mu receptor: 3b was a mu agonist whereas 3a was a mu antagonist.

Local injection of alkylating and nonalkylating dopamine receptor antagonists into rat basal forebrain: autoradiographic assessment of D2-like and D3 sites

N-chloroethyl derivatives of 7-hydroxy-1,2,3,4-tetrahydronaphthalene (7-OH-DPAT), 1-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), or fluphenazine were microinjected into rat nucleus accumbens (Acc), and receptor binding quantified autoradiographically after 24 h. EEDQ reduced [3H]nemonapride (D2-like receptors) binding in Acc (by 84%) and islands of Calleja (IC; 44%), without affecting [3H](+)-7-OH-DPAT (D3); N-chloroethyl-7-OH-DPATs blocked both radioligands in Acc and IC (30%-70%); fluphenazine had no effect.

[Synthesis and spectroscopic properties of rare earth and p-anisic acid with 1, 10-phenanthroline]

The title complex with the formula EuL3 x phen x H2O (phen=1, 10-phenathroline, HL=p-anisic acid) were synthesized and characterized by elemental analysis, molar conductivity, IR, UV, NMR etc.

Effects of aporphine isomers on rat prolactin

S(+)-aporphines are partial agonists at D2 dopamine receptors. High selectivity of anti-dopaminergic action in limbic vs. extrapyr amidal regions of rat brain and lack of induction of dopaminergic supersensitivity have suggested their potential as atypical antipsychotic drugs. Now, in testing for effects on circulating prolactin, a typical D2 antagonist haloperidol elevated, and potent agonist R(-)-11-hydroxy-N-propylnoraporphine lowered, serum prolactin levels in gentled male rats, while S(+)-N-propylnorapomorphine and its 11-monohydroxy analog had little or no effect, even at high doses. Lack of hyperprolactinemia adds to characteristics of S(+)-aporphines that are desirable in improved antipsychotics.

Receptor affinities of aporphine enantiomers in rat brain tissue

R(-) and S(+) enantiomers of apomorphine, N-n-propylnorapomorphine and 11-hydroxy-N-n-propylnorapomorphine were screened for affinity at over 40 representative sites in rat brain tissue that included amine, purine, amino acid and peptide receptors, transporters, ion channels, and effector components; only dopamine receptors and alpha-adrenoceptors showed appreciable affinity that was quantified further. The aporphines showed R(-) > S(+) isomeric selectivity as well as D2 > D1 selectivity at dopamine receptors. While R(-) isomers preferred alpha 2-adrenoceptors, S(+)-aporphines were alpha 1-selective, with similar affinity at alpha 1-adrenoceptors and dopamine D2 receptors. Interactions of S(+)-aporphines at alpha 1-adrenoceptors as well as dopamine D2 receptors may contribute to their unusual behavioral properties.

Presynaptic inhibition of dopamine synthesis in rat striatal tissue by enantiomeric mono- and dihydroxyaporphines

Presynaptic autoreceptor-mediated modulation of dopamine (DA) synthesis was evaluated as the inhibition of tyrosine hydroxylase activity by enantiomeric mono- and dihydroxyaporphines with minced striatal tissue from rat brain. The isomers of N-n-propylnorapomorphine (NPA) both inhibited tyrosine hydroxylase activity [IC50 = 0.3 and 1.0 microM for (R)-(-)- and (S)-(+)-NPA, respectively; R/S potency = 3.6]. Their effects were fully blocked by the nonselective DA receptor antagonist fluphenazine, as well as by the D2-selective antagonist spiperone, but not by the D1 antagonist SCH-23390. These results suggest a D2-type autoreceptor-mediated inhibition of DA synthesis, with limited enantiomeric selectivity of this catechol-aporphine. The corresponding monohydroxy analogs, (R)-(-)- and (S)-(+)-11-hydroxy-N-n-propylnoraporphine (11-OH-NPa) were about 100 times less potent (IC50 = 42 and 87 microM, respectively) than the NPA isomers in fully inhibiting the enzyme activity in normal tissue but, after depletion of endogenous DA by acute in vivo pretreatment with reserpine (which did not alter the number of D1 or D2 specific binding sites), (R)-(-)-11-OH-NPa was a highly potent but partial agonist (IC25 = 7 nM). Fluphenazine and spiperone fully antagonized the inhibition of tyrosine hydroxylase by (R)-(-)-11-OH-NPa in reserpinized tissue, but SCH-23390 was ineffective. Actions mediated by endogenous DA probably contribute to the effect of high concentrations of (R)-(-)-11-Oh-NPa to evoke a full inhibition of DA synthesis, but its high potency partial agonist effects appear to be mediated by D2-autoreceptors. (S)-(+)-11-OH-NPa was a very weak partial agonist in reserpinized tissue, with an IC25 = 30 microM (essentially the same as normal tissue); thus, (R)-(-)-11-OH-NPa was greater than 4,000 times more potent than its S-(+)-enantiomer in the absence of endogenous DA. These results demonstrate that NPA, which contains a catechol moiety, acts as a full agonist to inhibit striatal DA synthesis via a presynaptic autoreceptor of the D2 type, with only slight stereoselectivity, and that its monohydroxy analog is a very potent but partial D2 autoreceptor agonist, with very high stereoselectivity.

R(-) and S(+) stereoisomers of 11-hydroxy- and 11-methoxy-N-n-propylnoraporphine: central dopaminergic behavioral activity in the rat

R(-)11-Hydroxy-N-n-propylnoraporphine (11-OH-NPa) induced stereotyped behavior in the rat as potently (ED50 = 0.80 mg/kg, i.p.) as R(-)apomorphine (APO) and this effect was blocked by haloperidol; the 11-methoxy congener, R(-)11-MeO-NPa, had a weak effect (ED50 greater than 10 mg/kg) and the S(+) isomers had none. The isomer R(-)11-OH-NPa potentiated locomotion stimulated by apomorphine; S(+)11-OH-NPa inhibited it and the isomers of 11-MeO-NPa were inactive. Catecholaporphines usually are inactive orally, but both R(-) and S(+)11-OH-NPa were similarly potent after oral or parenteral administration. The isomer S(+)11-OH-NPa inhibited spontaneous and apomorphine-induced locomotion (ID50 = 1.8-2.7 mg/kg, p.o. and i.p.) and stereotyped behavior (ID50 = 3 mg/kg, p.o. or i.p.), all without inducing catalepsy. While apomorphine was short-acting (1-2 hr), the effects of R(-)11-OH-NPa persisted up to 6-7 hr and those of the S(+) isomer for at least 2.5 hr; moreover, the efficacy of R(-)11-OH-NPa increased markedly up to 3-4 hr, although its ED50 was independent of time (ED50 = 1.7-1.9 mg/kg, i.p. from 1-3 hr). The total effect of R(-)11-OH-NPa (p.o. or i.p.) over time was more than 10-times greater than that of injected apomorphine. These observations accord with the reported high (nM) affinity of 11-OH-NPa at cerebral DA receptor sites (D2 greater than D1) and weak interactions of the 11-methoxy congener. They support the conclusion that the R(-) and S(+) stereoisomers are neuropharmacologically active, respectively, as DA agonist and apparent antagonist, as was found with the enantiomers of N-n-propylnorapomorphine, perhaps due to the low intrinsic postsynaptic agonist activity of the S(+) isomers. Moreover, 11-OH-NPa was highly bioavailable orally and unusually long-acting; it may be absorbed slowly or have active metabolites. Hydroxy-substitution of aporphines at the 11-position, homologous to the 3-OH of DA, evidently is critical for affinity and activity at the DA receptor. These or other monohydroxyaporphines may represent leads to potentially useful DA agonist or antagonist drugs.

Synthesis and dopamine agonist and antagonist effects of (R)-(-)- and (S)-(+)-11-hydroxy-N-n-propylnoraporphine

The R-(-) and S-(+) enantiomers of 11-hydroxy-N-n-propylnoraporphine, (R)-3 and (S)-3, were synthesized in six steps from 1-(3-methoxy-2-nitrobenzyl)isoquinoline. Neuropharmacological evaluation of the R and S isomers (by affinity to dopamine receptor sites in rat brain tissues, induction of stereotyped behavior, and interaction with motor arousal induced by (R)-apomorphine in the rat) indicated that, similar to the 10,11-dihydroxy congener 2, both enantiomers can bind to dopamine receptors but that only (R)-3 activates them, whereas (S)-3 shows activity as a dopaminergic antagonist.