Exploration of macrocyclic peptide binders to the extracellular CRD domain of human receptor tyrosine kinase-like orphan receptor 1 (ROR1).

Elevated levels of receptor tyrosine kinase-like orphan receptor 1 (RORl) expression are observed in multiple hematological and solid tumors, but not in most of the healthy adult tissues, identifying ROR1 as an attractive target for tumor-specific therapy. Herein we will describe the discovery of macrocyclic peptides as binders of the extracellular Cysteine-Rich Domain (CRD) of human ROR1 via mRNA in vitro selection technology using the PDPS platform, followed by exploration of sidechain SAR of parent macrocycle peptides, fluorescently labeled analogs, and a Peptide Drug Conjugate (PDC). The parent macrocyclic peptides represented by Compound 1 and Compound 14 displayed nanomolar cell-based binding to ROR1 and relatively good internalization in 786-O and MDA-MB-231 tumor cell lines. However, these peptides were not observed to induce apoptosis in Mia PaCa-2 cells, a model pancreatic tumor cell line with a relatively low level of cell surface expression of ROR1.

Biochemical and Structural Characterization of a Peptidic Inhibitor of the YAP:TEAD Interaction That Binds to the α-Helix Pocket on TEAD.

The TEAD transcription factors are the most distal elements of the Hippo pathway, and their transcriptional activity is regulated by several proteins, including YAP. In some cancers, the Hippo pathway is deregulated and inhibitors of the YAP:TEAD interaction are foreseen as new anticancer drugs. The binding of YAP to TEAD is driven by the interaction of an α-helix and an Ω-loop present in its TEAD-binding domain with two distinct pockets at the TEAD surface. Using the mRNA-based display technique to screen a library of in vitro-translated cyclic peptides, we identified a peptide that binds with a nanomolar affinity to TEAD. The X-ray structure of this peptide in complex with TEAD reveals that it interacts with the α-helix pocket. Under our experimental conditions, this peptide can form a ternary complex with TEAD and YAP. Furthermore, combining it with a peptide binding to the Ω-loop pocket gives an additive inhibitory effect on the YAP:TEAD interaction. Overall, our results show that it is possible to identify nanomolar inhibitors of the YAP:TEAD interaction that bind to the α-helix pocket, suggesting that developing such compounds might be a strategy to treat cancers where the Hippo pathway is deregulated.

Identification of a PCSK9-LDLR disruptor peptide with in vivo function.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) regulates plasma low-density lipoprotein cholesterol (LDL-C) levels by promoting hepatic LDL receptor (LDLR) degradation. Therapeutic antibodies that disrupt PCSK9-LDLR binding reduce LDL-C concentrations and cardiovascular disease risk. The epidermal growth factor precursor homology domain A (EGF-A) of the LDLR serves as a primary contact with PCSK9 via a flat interface, presenting a challenge for identifying small molecule PCSK9-LDLR disruptors. We employ an affinity-based screen of 1013in vitro-translated macrocyclic peptides to identify high-affinity PCSK9 ligands that utilize a unique, induced-fit pocket and partially disrupt the PCSK9-LDLR interaction. Structure-based design led to molecules with enhanced function and pharmacokinetic properties (e.g., 13PCSK9i). In mice, 13PCSK9i reduces plasma cholesterol levels and increases hepatic LDLR density in a dose-dependent manner. 13PCSK9i functions by a unique, allosteric mechanism and is the smallest molecule identified to date with in vivo PCSK9-LDLR disruptor function.

Inhibition of Escherichia coli Lipoprotein Diacylglyceryl Transferase Is Insensitive to Resistance Caused by Deletion of Braun's Lipoprotein.

Lipoprotein diacylglyceryl transferase (Lgt) catalyzes the first step in the biogenesis of Gram-negative bacterial lipoproteins which play crucial roles in bacterial growth and pathogenesis. We demonstrate that Lgt depletion in a clinical uropathogenic Escherichia coli strain leads to permeabilization of the outer membrane and increased sensitivity to serum killing and antibiotics. Importantly, we identify G2824 as the first-described Lgt inhibitor that potently inhibits Lgt biochemical activity in vitro and is bactericidal against wild-type Acinetobacter baumannii and E. coli strains. While deletion of a gene encoding a major outer membrane lipoprotein, lpp, leads to rescue of bacterial growth after genetic depletion or pharmacologic inhibition of the downstream type II signal peptidase, LspA, no such rescue of growth is detected after Lgt depletion or treatment with G2824. Inhibition of Lgt does not lead to significant accumulation of peptidoglycan-linked Lpp in the inner membrane. Our data validate Lgt as a novel antibacterial target and suggest that, unlike downstream steps in lipoprotein biosynthesis and transport, inhibition of Lgt may not be sensitive to one of the most common resistance mechanisms that invalidate inhibitors of bacterial lipoprotein biosynthesis and transport. IMPORTANCE As the emerging threat of multidrug-resistant (MDR) bacteria continues to increase, no new classes of antibiotics have been discovered in the last 50 years. While previous attempts to inhibit the lipoprotein biosynthetic (LspA) or transport (LolCDE) pathways have been made, most efforts have been hindered by the emergence of a common mechanism leading to resistance, namely, the deletion of the gene encoding a major Gram-negative outer membrane lipoprotein lpp. Our unexpected finding that inhibition of Lgt is not susceptible to lpp deletion-mediated resistance uncovers the complexity of bacterial lipoprotein biogenesis and the corresponding enzymes involved in this essential outer membrane biogenesis pathway and potentially points to new antibacterial targets in this pathway.

Design of Thioether Cyclic Peptide Scaffolds with Passive Permeability and Oral Exposure.

Advances in the design of permeable peptides and in the synthesis of large arrays of macrocyclic peptides with diverse amino acids have evolved on parallel but independent tracks. Less precedent combines their respective attributes, thereby limiting the potential to identify permeable peptide ligands for key targets. Herein, we present novel 6-, 7-, and 8-mer cyclic peptides (MW 774-1076 g·mol-1) with passive permeability and oral exposure that feature the amino acids and thioether ring-closing common to large array formats, including DNA- and RNA-templated synthesis. Each oral peptide herein, selected from virtual libraries of partially N-methylated peptides using in silico methods, reflects the subset consistent with low energy conformations, low desolvation penalties, and passive permeability. We envision that, by retaining the backbone N-methylation pattern and consequent bias toward permeability, one can generate large peptide arrays with sufficient side chain diversity to identify permeability-biased ligands to a variety of protein targets.

A new modular radiographic classification of adult idiopathic scoliosis as an extension of the Lenke classification of adolescent idiopathic scoliosis.

PURPOSE: To propose and test the reliability of a radiographic classification system for adult idiopathic scoliosis. METHODS: A three-component radiographic classification for adult idiopathic scoliosis consisting of curve type, a lumbosacral modifier, and a global alignment modifier is presented. Twelve spine surgeons graded 30 pre-marked cases twice, approximately 1 week apart. Case order was randomized between sessions. RESULTS: The interrater reliability (Fleiss' kappa coefficient) for curve type was 0.660 and 0.798, for the lumbosacral modifier 0.944 and 0.965, and for the global alignment modifier 0.922 and 0.916, for round 1 and 2 respectively. Mean intrarater reliability was 0.807. CONCLUSIONS: This new radiographic classification of adult idiopathic scoliosis maintains the curve types from the Lenke classification and introduces the lumbosacral and global alignment modifiers. The reliability of the lumbosacral modifier and global alignment modifier shows near perfect agreement, and sets the foundation for further studies to validate the reliability, utility, and applicability of this classification system.

Discovery, X-ray structure and CPP-conjugation enabled uptake of p53/MDM2 macrocyclic peptide inhibitors.

Mouse double minute 2 homolog (MDM2, Hdm2) is an important negative regulator of the tumor suppressor p53. Using a mRNA based display technique to screen a library of >1012 in vitro-translated cyclic peptides, we have identified a macrocyclic ligand that shows picomolar potency on MDM2. X-Ray crystallography reveals a novel binding mode utilizing a unique pharmacophore to occupy the Phe/Trp/Leu pockets on MDM2. Conjugation of a cyclic cell-penetrating peptide (cCPP) to the initially non cell-permeable ligand enables cellular uptake and a pharmacodynamic response in SJSA-1 cells. The demonstrated enhanced intracellular availability of cyclic peptides that are identified by a display technology exemplifies a process for the application of intracellular tools for drug discovery projects.

State of the union: a review of lumbar fusion indications and techniques for degenerative spine disease.

Lumbar fusion is an accepted and effective technique for the treatment of lumbar degenerative disease. The practice has evolved continually since Albee and Hibbs independently reported the first cases in 1913, and advancements in both technique and patient selection continue through the present day. Clinical and radiological indications for surgery have been tested in trials, and other diagnostic modalities have developed and been studied. Fusion practices have also advanced; instrumentation, surgical approaches, biologics, and more recently, operative planning, have undergone stark changes at a seemingly increasing pace over the last decade. As the general population ages, treatment of degenerative lumbar disease will become a more prevalent-and costlier-issue for surgeons as well as the healthcare system overall. This review will cover the evolution of indications and techniques for fusion in degenerative lumbar disease, with emphasis on the evidence for current practices.

Evaluation of C2 pedicle screw placement via the freehand technique by neurosurgical trainees.

OBJECTIVE Freehand placement of C2 instrumentation is technically challenging and has a learning curve due the unique anatomy of the region. This study evaluated the accuracy of C2 pedicle screws placed via the freehand technique by neurosurgical resident trainees. METHODS The authors retrospectively reviewed all patients treated at the LAC+USC Medical Center undergoing C2 pedicle screw placement in which the freehand technique was used over a 1-year period, from June 2016 to June 2017; all procedures were performed by neurosurgical residents. Measurements of C2 were obtained from preoperative CT scans, and breach rates were determined from coronal reconstructions on postoperative scans. Severity of breaches reflected the percentage of screw diameter beyond the cortical edge (I = < 25%; II = 26%-50%; III = 51%-75%; IV = 76%-100%). RESULTS Neurosurgical residents placed 40 C2 pedicle screws in 24 consecutively treated patients. All screws were placed by or under the guidance of Pham, who is a postgraduate year 7 (PGY-7) neurosurgical resident with attending staff privileges, with a PGY-2 to PGY-4 resident assistant. The authors found an average axial pedicle diameter of 5.8 mm, axial angle of 43.1°, sagittal angle of 23.0°, spinal canal diameter of 25.1 mm, and axial transverse foramen diameter of 5.9 mm. There were 17 screws placed by PGY-2 residents, 7 screws placed by PGY-4 residents, and 16 screws placed by the PGY-7 resident. The average screw length was 26.0 mm, with a screw diameter of 3.5 mm or 4.0 mm. There were 7 total breaches (17.5%), of which 4 were superior (10.0%) and 3 were lateral (7.5%). There were no medial breaches. The breaches were classified as grade I in 3 cases (42.9%), II in 3 cases (42.9%), III in 1 case (14.3%), and IV in no cases. There were 3 breaches that occurred via placement by a PGY-2 resident, 3 breaches by a PGY-4 resident, and 1 breach by the PGY-7 resident. There were no clinical sequelae due to these breaches. CONCLUSIONS Freehand placement of C2 pedicle screws can be done safely by neurosurgical residents in early training. When breaches occurred, they tended to be superior in location and related to screw length choice, and no breaches were found to be clinically significant. Controlled exposure to this unique anatomy is especially pertinent in the era of work-hour restrictions.

In vitro selection of multiple libraries created by genetic code reprogramming to discover macrocyclic peptides that antagonize VEGFR2 activity in living cells.

We report the in vitro selection of thioether-macrocyclized peptides against vascular endothelial growth factor receptor 2 (VEGFR2) from multiple, highly diverse peptide libraries constructed utilizing genetic code reprogramming. The macrocyclic peptide libraries consisted of combinations of four types of amino acid linkers for cyclization and two types of elongator amino acid compositions, including four backbone-modified non-proteinogenic amino acids. Affinity selection from these libraries, using our recently developed TRAP (Transcription-translation coupled with Association of Puromycin-linker) display, yielded multiple anti-VEGFR2 macrocyclic peptide leads. Further antagonizing activity-based screening of the chemically synthesized lead peptides identified a potent macrocyclic peptide that inhibited VEGF-induced VEGFR2 autophosphorylation, proliferation, and angiogenesis of living vascular endothelial cells. The TRAP display-based selection from multiple, highly diverse peptide libraries followed by activity-based screening of selected peptides is a powerful strategy for discovering biologically active peptides targeted to various biomolecules.

TRAP display: a high-speed selection method for the generation of functional polypeptides.

Here, we describe a novel method that enables high-speed in vitro selection of functional peptides, peptidomimetics, and proteins via a simple procedure. We first developed a new cell-free translation system, the TRAP system (transcription-translation coupled with association of puromycin linker), which automatically produces a polypeptide library through a series of sequential reactions: transcription, association of puromycin-DNA linker, translation, and conjugation between the nascent polypeptide and puromycin-DNA linker. We then applied the TRAP system for the selection of macrocyclic peptides against human serum albumin. Six rounds of selection using TRAP display were performed in approximately 14 h, yielding macrocyclic peptides with nanomolar affinity to their target protein. Because TRAP display enables high-speed selection of functional polypeptides, it will facilitate the generation of various polypeptides that are useful for biological and therapeutic applications.

Charging of tRNAs using ribozymes and selection of cyclic peptides containing thioethers.

In vitro selection methods represent a powerful approach toward identifying high-affinity peptide ligands from highly diverse peptide libraries against a desired target. We herein describe a method for the display and selection of cyclic thioether peptide libraries. Reprogramming the initiation event from fMet to an N-chloroacetyl-amino acid by utilizing flexizyme to rapidly and efficiently prepare the aa-tRNA can be effectively used to initiate translation, upon which the thiol group of an inserted cysteine at the C terminus of the designed library spontaneously reacts to yield a nonreducible cyclic thioether peptide readily compatible with any in vitro display methods. Thus, cyclic peptides already in a nonreducible stable form can be selected directly against the target of interest.

The Down syndrome critical region gene 1 short variant promoters direct vascular bed-specific gene expression during inflammation in mice.

Down syndrome critical region gene 1 (DSCR-1) short variant (DSCR-1s) is an inhibitor of calcineurin/NFAT signaling encoded by exons 4-7 of DSCR1. We previously reported that VEGF induces DSCR-1s expression in endothelial cells, which in turn negatively feeds back to attenuate endothelial cell activation. Here, in order to characterize the role of the promoter that drives DSCR-1s expression in mediating inducible expression in vivo and to determine the functional relevance of DSCR-1s in inflammation, we targeted a DNA construct containing 1.7 kb of the human DSCR1s promoter coupled to the lacZ reporter to the hypoxanthine guanine phosphoribosyl transferase (Hprt) locus of mice. We determined that lacZ was uniformly expressed in the endothelium of transgenic embryos but was markedly downregulated postnatally. Systemic administration of VEGF or LPS in adult mice resulted in cyclosporine A-sensitive reactivation of the DSCR1s promoter and endogenous gene expression in a subset of organs, including the heart and brain. The DSCR1s promoter was similarly induced in the endothelium of tumor xenografts. In a mouse model of endotoxemia, DSCR-1s-deficient mice demonstrated increased sepsis mortality, whereas adenovirus-mediated DSCR-1s overexpression protected against LPS-induced lethality. Collectively, these data suggest that the DSCR1s promoter directs vascular bed-specific expression in activated endothelium and that DSCR-1s serves to dampen the host response to infection.

Partial blockage of sterol biosynthesis with a squalene synthase inhibitor in early postnatal Niemann-Pick type C npcnih null mice brains reduces neuronal cholesterol accumulation, abrogates astrogliosis, but may inhibit myelin maturation.

Niemann-Pick C disease (NPC) is a fatal, neurovisceral genetic disorder. Cell culture studies showed that NPC1 or NPC2 mutations cause malfunctions in cellular cholesterol trafficking and lead to accumulation of cholesterol and other lipids in the late endo/lysosomes. Previous work showed that neuronal cholesterol accumulation occurs in the brains of young postnatal NPC1-/- mice. Here, to evaluate the potential of partial blockage of cholesterol biosynthesis as a therapy for the NPC disease, we first developed a simple method to monitor the relative rates of lipid biosynthesis in mice brains. We next administered squalene synthase inhibitor (SSI) CP-340868 to young mice. The results show that treating 8-day-old NPC1-/- mice with CP-340868 for 6 days significantly inhibits cholesterol biosynthesis in the mice brains. It reduces neuronal cholesterol accumulation, reduces GM3 ganglioside accumulation, and diminishes astrogliosis in the brain. These results suggest that neuronal cholesterol accumulation contributes to early pathogenesis in the NPC1-/- mice brains. The SSI treatment also reduced brain galactolipid content, suggesting that blocking endogenous cholesterol synthesis in the young mice brains may disrupt the normal myelin maturation processes. The methods described in the current work have general applicability for lipid metabolism studies in mice brains in various pathophysiological conditions.

Plasma membrane rafts complete cholesterol synthesis by participating in retrograde movement of precursor sterols.

Mammalian cells synthesize significant amounts of precursor sterols, in addition to cholesterol, at the endoplasmic reticulum (ER). The newly synthesized sterols rapidly move to the plasma membrane (PM). The mechanism by which precursor sterols move back to the ER for their enzymatic processing to cholesterol is essentially unknown. Here we performed pulse-chase experiments and showed that the C29/C30 sterols rapidly move from the PM to the ER and are converted to cholesterol. The retrograde precursor sterol transport is largely independent of the Niemann-Pick type C proteins, which play important roles in late endosomal cholesterol transport. In contrast, disrupting lipid rafts significantly retards the conversion of C29/C30 and C28 sterols to cholesterol, causing the accumulation of precursor sterols at the PM. Our results reveal a previously undisclosed function of the PM lipid rafts: they bring cholesterol biosynthesis to completion by participating in the retrograde movement of precursor sterols back to the ER.

Alzheimer's disease: cholesterol, membrane rafts, isoprenoids and statins.

Alzheimer's disease (AD) is a heterogeneous neurodegenerative disorder and the most prevalent form of dementia worldwide. AD is characterized pathologically by amyloid-? plaques, neurofibrillary tangles and neuronal loss, and clinically by a progressive loss of cognitive abilities. At present, the fundamental molecular mechanisms underlying the disease are unclear and no treatment for AD is known. Epidemiological evidence continues to mount linking vascular diseases, such as hypertension and diabetes, and hypercholesterolaemia with an increased risk for developing AD. A growing amount of evidence suggests a mechanistic link between cholesterol metabolism in the brain and the formation of amyloid plaques in AD development. Cholesterol and statins clearly modulate ?-amyloid precursor protein (?APP) processing in cell culture and animal models. Statins not only reduce endogenous cholesterol synthesis but also exert other various pleiotrophic effects, such as the reduction in protein isoprenylation. Through these effects statins modulate a variety of cellular functions involving both cholesterol (and membrane rafts) and isoprenylation. Although clearly other factors, such as vascular inflammation, oxidative stress and genetic factors, are intimately linked with the progression of AD, this review focuses on the present research findings describing the effect of cholesterol, membrane rafts and isoprenylation in regulating ?APP processing and in particular ?-secretase complex assembly and function and AD progression, along with consideration for the potential role statins may play in modulating these events.

Establishment of a high sensitivity plasma assay for human pentraxin3 as a marker for unstable angina pectoris.

OBJECTIVE: Plasma pentraxin 3 (PTX3) levels are increased in patients with acute myocardial infarction, yet its involvement in unstable angina pectoris (UAP) remains unclear. To critically evaluate the role of PTX3 in UAP, a sensitive and precise measurement of PTX3 concentration is needed. METHODS AND RESULTS: We established a high sensitive plasma ELISA assay system for the detection of PTX3 using monoclonal antibodies. The lower limit of detection of our ELISA was 0.1 ng/mL, sensitivity far greater than the current commercially available kit. Plasma samples were obtained from 162 consecutive patients treated for hypertension, hyperlipidemia, diabetes mellitus, or cardiovascular disease at a physician's office. PTX3 was not associated with any known coronary risk factors. Additionally, we collected plasma samples from 252 consecutive subjects admitted to a university hospital for coronary artery assessment by coronary angiography. PTX3 was significantly increased in patients in whom coronary intervention was performed. We further analyzed the plasma level of PTX3 in 52 patients with effort angina (EAP) and 16 patients with UAP. Compared with the control group, PTX3 were significantly higher in the UAP group. CONCLUSIONS: The levels of plasma PTX3 were increased in patients with arterial inflammation, especially UAP. This PTX3 detection system will be useful for the prediction of UAP.

Wilms' tumor 1-associating protein regulates G2/M transition through stabilization of cyclin A2 mRNA.

Wilms' tumor 1-associating protein (WTAP) has been reported to be a ubiquitously expressed nuclear protein. Although a relation to splicing factors has been postulated, its actual physiological function still remains to be elucidated. To investigate the role of WTAP, we generated WTAP-knockout mice and performed small interfering RNA (siRNA)-mediated knockdown analyses in primary cultured cells. In DNA microarrays using human umbilical vein endothelial cells, WTAP-targeted siRNA treatment resulted in markedly reduced expression of cell-cycle-related genes. siRNA-mediated WTAP knockdown down-regulated the stability of cyclin A2 mRNA through a nine-nucleotide essential sequence in cyclin A2 mRNA 3' UTR. WTAP knockdown induced G2 accumulation, which is partially rescued by adenoviral overexpression of cyclin A2. Moreover, WTAP-null mice exhibited proliferative failure with death resulting at approximately embryonic day 6.5, an etiology almost identical to cyclin A2-null mice. Collectively, these findings establish WTAP as an essential factor for the stabilization of cyclin A2 mRNA, thereby regulating G2/M cell-cycle transition.

Histone deacetylase inhibitor reduces monocyte adhesion to endothelium through the suppression of vascular cell adhesion molecule-1 expression.

OBJECTIVE: Tumor necrosis factor (TNF)-alpha initiates numerous changes in endothelial cell (EC) gene expression that contributes to the pathology of various diseases including inflammation. We hypothesized that TNF-alpha-mediated gene induction involves multiple signaling pathways, and that inhibition of one or more of these pathways may selectively target subsets of TNF-alpha-responsive genes and functions. METHODS AND RESULTS: Human umbilical vein endothelial cells (ECs) were preincubated with inhibitors of PI3 kinase (LY294002), histone deacetylases (HDAC) (trichostatin A [TSA]), de novo protein synthesis (CHX), proteasome (MG-132), and GATA factors (K-11430) before exposure to TNF-alpha at 4 hours and analyzed by microarray. TNF-alpha-mediated induction of vascular cell adhesion molecule-1 (VCAM-1) was attenuated by all of these inhibitors, whereas in contrast, stimulation of intercellular adhesion molecule-1 (ICAM-1) was blocked by MG-132 alone. Moreover TSA blocked TNF-alpha-mediated induction of monocyte adhesion both in vitro and in vivo through the suppression of VCAM-1. Further analysis demonstrated that HDAC3 plays a significant role in the regulation of TNF-alpha-mediated VCAM-1 expression. CONCLUSIONS: TNF-alpha activates ECs via multiple signaling pathways, and these pathways may be selectively targeted to modulate EC function. Moreover, TSA treatment reduced monocyte adhesion via VCAM-1 suppression in vitro and in vivo, suggesting that TSA might be useful for the attenuation of the inflammatory response in EC.