Cell-free biosynthesis and engineering of ribosomally synthesized lanthipeptides.

Ribosomally synthesized and post-translationally modified peptides (RiPPs) are a major class of natural products with diverse chemical structures and potent biological activities. A vast majority of RiPP gene clusters remain unexplored in microbial genomes, which is partially due to the lack of rapid and efficient heterologous expression systems for RiPP characterization and biosynthesis. Here, we report a unified biocatalysis (UniBioCat) system based on cell-free gene expression for rapid biosynthesis and engineering of RiPPs. We demonstrate UniBioCat by reconstituting a full biosynthetic pathway for de novo biosynthesis of salivaricin B, a lanthipeptide RiPP. Next, we delete several protease/peptidase genes from the source strain to enhance the performance of UniBioCat, which then can synthesize and screen salivaricin B variants with enhanced antimicrobial activity. Finally, we show that UniBioCat is generalizable by synthesizing and evaluating the bioactivity of ten uncharacterized lanthipeptides. We expect UniBioCat to accelerate the discovery, characterization, and synthesis of RiPPs.

Harnessing the potential of long non-coding RNAs in breast cancer: from etiology to treatment resistance and clinical applications.

Breast cancer (BC) is the most common malignancy among women and a leading cause of cancer-related deaths of females worldwide. It is a complex and molecularly heterogeneous disease, with various subtypes that require different treatment strategies. Despite advances in high-resolution single-cell and multinomial technologies, distant metastasis and therapeutic resistance remain major challenges for BC treatment. Long non-coding RNAs (lncRNAs) are non-coding RNAs with more than 200 nucleotides in length. They act as competing endogenous RNAs (ceRNAs) to regulate post-transcriptional gene stability and modulate protein-protein, protein-DNA, and protein-RNA interactions to regulate various biological processes. Emerging evidence suggests that lncRNAs play essential roles in human cancers, including BC. In this review, we focus on the roles and mechanisms of lncRNAs in BC progression, metastasis, and treatment resistance, and discuss their potential value as therapeutic targets. Specifically, we summarize how lncRNAs are involved in the initiation and progression of BC, as well as their roles in metastasis and the development of therapeutic resistance. We also recapitulate the potential of lncRNAs as diagnostic biomarkers and discuss their potential use in personalized medicine. Finally, we provide lncRNA-based strategies to promote the prognosis of breast cancer patients in clinical settings, including the development of novel lncRNA-targeted therapies.

Identification of Clec7a as the therapeutic target of rTMS in alleviating Parkinson's disease: targeting neuroinflammation.

Parkinson's disease (PD) is a neurodegenerative disease. Repetitive transcranial magnetic stimulation (rTMS) is a therapeutic tool in PD. High-throughput sequencing was performed to screen potential therapeutic targets in unilaterally 6-hydroxydopamine (6-OHDA)-lesioned rats. The candidate gene, Clec7a, was screened out and validated. Clec7a is a pattern recognition receptor involved in neuroinflammation. The higher expression of Clec7a was observed in the substantia nigra (SN) and striatum of PD rats with dopaminergic neurons damage and was mainly localized in the microglial. Adeno-associated virus (AAV)-mediated specific knockdown of Clec7a in microglial alleviated 6-OHDA induced motor deficits and nigrostriatal dopaminergic neuron damage of rats, as evidenced by the increase of tyrosine hydroxylase (TH) -positive neurons in SN, as well as dopaminergic nerve fibers in the striatum. Clec7a knockdown restrained the neuroinflammation by suppressing inflammatory factors (IFN-γ, TNF-α, IL-1ß, IL-18, and IL-6) release in SN, which might result from enhanced Arg-1 expression (M2 polarization) and defective inducible nitric oxide synthase (iNOS) expression (M1 polarization). The same phenomena were also observed in the LPS inflammatory rat model of PD. In vitro, α-synuclein fibrils induced upregulation of Clec7a expression and microglia polarization to a pro-inflammatory state of BV2 cells, leading to increased release of cytokines. However, Clec7a knockdown reversed those changes and induced a shift to an anti-inflammatory phenotype in BV2 cells. In conclusion, our study suggested that Clec7a was involved in PD pathogenesis, and its inhibition might protect rats from PD by depressing neuroinflammation through microglial polarization.

Stapled NRPS enhances the production of valinomycin in Escherichia coli.

Nonribosomal peptides (NRPs) are a large family of secondary metabolites with notable bioactivities, which distribute widely in natural resources across microbes and plants. To obtain these molecules, heterologous production of NRPs in robust surrogate hosts like Escherichia coli represent a feasible approach. However, reconstitution of the full biosynthetic pathway in a host often leads to low productivity, which is at least in part due to the low efficiency of enzyme interaction in vivo except for the well-known reasons of metabolic burden (e.g., expression of large NRP synthetases-NRPSs with molecular weights of >100 kDa) and cellular toxicity on host cells. To enhance the catalytic efficiency of large NRPSs in vivo, here we propose to staple NRPS enzymes by using short peptide/protein pairs (e.g., SpyTag/SpyCatcher) for enhanced NRP production. We achieve this goal by introducing a stapled NRPS system for the biosynthesis of the antibiotic NRP valinomycin in E. coli. The results indicate that stapled valinomycin synthetase (Vlm1 and Vlm2) enables higher product accumulation than those two free enzymes (e.g., the maximum improvement is nearly fourfold). After further optimization by strain and bioprocess engineering, the final valinomycin titer maximally reaches about 2800 µg/L, which is 73 times higher than the initial titer of 38 µg/L. We expect that stapling NRPS enzymes will be a promising catalytic strategy for high-level biosynthesis of NRP natural products.

Pearls & Oy-sters: A Case Report of Holmes Tremor Due to Nigrostriatal Dopamine Disruption That Responded to Dopamine Replacement Therapy.

Holmes tremor (HT), also known as midbrain, rubral, or cerebellar pathway outflow tremor, occurs because of disturbances of the cerebellothalamic pathway. This tremor is usually related to lesions in the midbrain peduncular region involving the superior cerebellar peduncle, the red nucleus, and possibly the nigrostriatal circuitry. Common etiologies resulting in HT include tumor, ischemia, and demyelination. We report a case of progressive left-sided HT in an otherwise healthy man with additional symptoms of parkinsonism, hypoesthesia, right oculomotor nerve palsy, cognitive dysfunction, and hypersomnolence. Imaging investigations revealed a right-sided thalamic and midbrain glioma. Dopamine transport imaging demonstrated significant dopaminergic denervation in the right caudate and putamen. The degree of striatal dopamine transporter deficiency was more severe than expected in a patient with Parkinson disease. A trial of dopaminergic agent resulted in significant improvement of the tremor and associated symptoms. Interruption of the nigrostriatal pathway can occur in cases of HT because of midbrain peduncular lesion. The striatal dopaminergic function imaging may have a role in assessing presynaptic dopamine dysfunction and guiding treatment.

Intraoperative changes in the H-reflex pathway during deep brain stimulation surgery for Parkinson's disease: A potential biomarker for optimal electrode placement.

BACKGROUND: Deep Brain Stimulation (DBS) targeting the subthalamic nucleus (STN) and globus pallidus interna (GPi) is an effective treatment for cardinal motor symptoms and motor complications in Parkinson's Disease (PD). However, malpositioned DBS electrodes can result in suboptimal therapeutic response. OBJECTIVE: We explored whether recovery of the H-reflex-an easily measured electrophysiological analogue of the stretch reflex, known to be altered in PD-could serve as an adjunct biomarker of suboptimal versus optimal electrode position during STN- or GPi-DBS implantation. METHODS: Changes in soleus H-reflex recovery were investigated intraoperatively throughout awake DBS target refinement across 26 nuclei (14 STN). H-reflex recovery was evaluated during microelectrode recording (MER) and macrostimulation at multiple locations within and outside target nuclei, at varying stimulus intensities. RESULTS: Following MER, H-reflex recovery normalized (i.e., became less Parkinsonian) in 21/26 nuclei, and correlated with on-table motor improvement consistent with an insertional effect. During macrostimulation, H-reflex recovery was maximally normalized in 23/26 nuclei when current was applied at the location within the nucleus producing optimal motor benefit. At these optimal sites, H-reflex normalization was greatest at stimulation intensities generating maximum motor benefit free of stimulation-induced side effects, with subthreshold or suprathreshold intensities generating less dramatic normalization. CONCLUSION: H-reflex recovery is modulated by stimulation of the STN or GPi in patients with PD and varies depending on the location and intensity of stimulation within the target nucleus. H-reflex recovery shows potential as an easily-measured, objective, patient-specific, adjunct biomarker of suboptimal versus optimal electrode position during DBS surgery for PD.

Efficacy of Sox10 Promoter Methylation in the Diagnosis of Intestinal Neuronal Dysplasia From the Peripheral Blood.

OBJECTIVES: Intestinal neuronal dysplasia (IND) is a common malformation of the enteric nervous system. Diagnosis requires a full-thickness colonic specimen and an experienced pathologist, emphasizing the need for noninvasive analytical methods. Recently, the methylation level of the Sox10 promoter has been found to be critical for enteric nervous system development. However, whether it can be used for diagnostic purposes in IND is unclear. METHODS: Blood and colon specimens were collected from 32 patients with IND, 60 patients with Hirschsprung disease (HD), and 60 controls. Sox10 promoter methylation in the blood and the Sox10 expression level in the colon were determined, and their correlation was analyzed. The diagnostic efficacy of blood Sox10 promoter methylation was analyzed by receiver operating characteristic curve. RESULTS: The blood level of Sox10 promoter methylation at the 32nd locus was 100% (90%-100%; 95% confidence interval [CI], 92.29%-96.37%) in control, 90% (80%-90%; 95% CI, 82.84%-87.83%) in HD, and 60% (50%-80%; 95% CI, 57.12%-69.76%) in IND specimens. Sox10 promoter methylation in the peripheral blood was negatively correlated with Sox10 expression in the colon, which was low in control, moderate in HD, and high in IND specimens (r = -0.89). The area under the curve of Sox10 promoter methylation in the diagnosis of IND was 0.94 (95% CI, 0.874-1.000, P = 0.000), with a cutoff value of 85% (sensitivity, 90.6%; specificity, 95.0%). By applying a cutoff value of 65%, promoter methylation was more indicative of IND than HD. DISCUSSION: The analysis of Sox10 promoter methylation in the peripheral blood can be used as a noninvasive method for IND diagnosis.

Two new C13-norisoprenoids from Solanum lyratum.

Two new C(13)-norisoprenoids, named lyratols E and F (1-2), were isolated from the whole plant of Solanum lyratum Thunb, and their structures were elucidated by extensive spectroscopic analyses. In vitro, two new compounds were found to show significant cytotoxicity against selected cancer cells including P-388 and HT-29.

Neurologic complications of bariatric surgery.

With the rapid rise in the number of bariatric surgeries performed for morbid obesity, several short- and long-term neurologic complications of this procedure have been identified. These complications affect various levels of the neuraxis, and most are likely secondary to deficiency of essential minerals and vitamins. We report on 3 patients who developed unusual and severe neurologic deficits after undergoing bariatric surgery, including Wernicke encephalopathy, acute and rapidly progressive polyneuropathy, myelopathy, and visual deficits. Two developed clinical features of Parkinsonism, a complication not previously reported in this patient population. None of our patients had attended a nutrition clinic postoperatively. All 3 had a rapid weight loss and intractable vomiting preceding the development of neurologic symptoms, and all were found to have significant vitamin deficiencies. Replacement of vitamins resulted in a slow and variable degree of neurologic recovery. Patients undergoing bariatric surgery should have close monitoring of their nutritional status postoperatively. Routine supplementation of vitamins and minerals may be a cost-effective strategy for preventing neurologic complications in these patients.

The role of Ca2+ channel modulation in the neuroprotective actions of estrogen in beta-amyloid protein and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) cytotoxic models.

Physiologically relevant concentrations of 17beta-estradiol (E2) are neuroprotective in both beta-amyloid protein 25-35 (Abeta) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced cytotoxicity in SK-N-SH cells. MPTP, but not Abeta, induces apoptosis in this cell line. The L-type calcium channel blocker nifedipine or decreased extracellular Ca(2+) concentration blocked Abeta-induced cell death, but not MPTP-induced cell death. Other blockers selective for different Ca(2+) channel subtypes had no effects on either Abeta or MPTP induced death. Western blot analysis for L-type Ca(2+) channel alpha(1)-subunits demonstrated that Abeta increases the expression of the neuronal alpha(1C) and alpha(1D) subunits of L-type channels. Both E2 and nifedipine inhibit the increase in expression of these by Abeta. MPTP also increases expression of alpha(1C) and alpha(1D), but the increases were not influenced by E2 or nifedipine. These observations suggested that Abeta cytotoxicity in SK-N-SH cells may involve increased availability of calcium to cells, whereas MPTP induced cytotoxicity does not require extracellular Ca(2+). Both cytotoxic models were associated with increased expression of Ca(2+) channel alpha(1) subunits, and neuroprotection associated with inhibition of that increase. These studies reveal that nifedipine, in addition to its direct action of nifedipine on Ca(2+) channels, may also protect neurons from Abeta toxicity through the suppression of the channel protein overexpression. A new action of dihydropyridines (DHPs) may be considered in the regulation of calcium homeostasis.

The neuroprotective effects of estrogen in SK-N-SH neuroblastoma cell cultures.

Estrogen has been considered to be a neuroprotectant and a neuromodulator in many neuronal cell lines and tissue preparations. The protective effects of estrogen may be mediated through classical estrogen receptors (ERs), or may be due to its anti-oxidant properties which are independent of receptors. The current studies show that 17beta-estradiol (E2) is neuroprotective against beta-amyloid protein 25-35 (Abeta)-, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-, high density culture condition-, and serum deprivation-induced neuronal death in SK-N-SH human neuroblastoma cells. SK-N-SH cells express ERbeta, but not ERalpha, as detected by Western blot analysis. Among all the insults, MPTP, high density culture and serum deprivation induce apoptotic cell death in this cell system as detected by ELISA determination of mono/oligonucleosomes and DNA laddering, while Abeta induces necrotic cell death. The protective effects of E2 are abolished by the addition of tamoxifen and ICI 182,780 in the MPTP treated cells, but not in the other models, suggesting that the effect of E2 in the MPTP model is probably associated with activation of ERbeta. The addition of ICI 182,780 shows a mitogenic effect in SK-N-SH cells in the presence of E2 in control culture or in the Abeta treated groups. Also, ICI 182,780 induced expression of ERalpha. Collectively, the current studies suggest that E2 is neuroprotective in apoptotic and necrotic death induced by multiple insults in SK-N-SH human neuroblastoma cells. Involvement of ER is insult type dependent. ICI 182,780 is able to influence the expression of ERs, probably through upregulation of ERalpha when ERbeta is totally antagonized.

The establishment of a reliable cytotoxic system with SK-N-SH neuroblastoma cell culture.

A reliable in vitro cytotoxic system is essential in neurocytotoxic and neuroprotective research. The present study examined four cytotoxic insults with the SK-N-SH human neuroblastoma cell line. These were beta-amyloid protein (Abeta), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), high density culture, and serum deprivation induced neuronal death. These insults induced significant reduction in cell numbers after 96 h culture, in a concentration dependent manner. Among all the insults, MPTP, serum deprivation, and high density culture induced apoptosis after 96 h, while Abeta presumably induced necrotic neuronal death since apoptosis was not detectable. The p38 MAP kinase inhibitor, SB203580 (1 microM), and the PKC inhibitor, chelerythrine (5 microM) successfully inhibited the loss in viability caused by Abeta and the high density culture, respectively. Other kinase inhibitors, including the non-specific protein kinase inhibitor, H7, the PKA inhibitor 14-22 Amide, the PKG inhibitor, KT5823, and the protein tyrosine kinase inhibitor, AG18 had no effect on any of the four cytotoxic models. This system allows the study of neuroprotection under conditions where the different pathways and mechanisms of the neurons can be considered within one cellular system, removing variations which may be due to different cell type studied. The present studies describe an effective model system for screening potential neuroprotective agents.