Glucagon Like Peptide 1 Receptor Agonists for Targeted Delivery of Antisense Oligonucleotides to Pancreatic Beta Cell.

The extra hepatic delivery of antisense oligonucleotides (ASOs) remains a challenge and hampers the widespread application of this powerful class of therapeutic agents. In that regard, pancreatic beta cells are a particularly attractive but challenging cell type because of their pivotal role in diabetes and the fact that they are refractory to uptake of unconjugated ASOs. To circumvent this, we have expanded our understanding of the structure activity relationship of ASOs conjugated to Glucagon Like Peptide 1 Receptor (GLP1R) agonist peptide ligands. We demonstrate the key role of the linker chemistry and its optimization to design maleimide based conjugates with improved in vivo efficacy. In addition, truncation studies and scoping of a diverse set of GLP1R agonists proved fruitful to identify additional targeting ligands efficacious in vivo including native hGLP1(7-36)NH2. Variation of the carrier peptide also shed some light on the dramatic impact of subtle sequence differences on the corresponding ASO conjugate performance in vivo, an area which clearly warrant further investigations. We have confirmed the remarkable potential of GLP1R agonist conjugation for the delivery of ASOs to pancreatic beta cell by effectively knocking down islet amyloid polypeptide (IAPP) mRNA, a potential proapoptotic target, in mice.

Is GPR146 really the receptor for proinsulin C-peptide?

Proinsulin C-peptide has previously been proposed to interact with a G-protein coupled receptor (GPCR), specifically the orphan receptor GPR146. To investigate the potential of C-peptide in treating complications of diabetes, such as kidney damage, it is necessary to understand its mode of action. We used CHO-K1 cells expressing human GPR146 to study human and murine C-peptide in dynamic mass redistribution and GPCR ß-arrestin assays, as well as with fluorescence confocal microscopy. Neither assay revealed any significant intracellular response to C-peptide at concentrations of up to 33 µM. We observed no internalisation of C-peptide by fluorescence microscopy. Our results do not support GPR146 as the receptor for C-peptide, but suggest that further investigations of the mode of action of C-peptide should be undertaken.

Small molecule inducers of ABCA1 and apoE that act through indirect activation of the LXR pathway.

apoE is the primary lipid carrier within the CNS and the strongest genetic risk factor for late onset Alzheimer's disease (AD). apoE is primarily lipidated via ABCA1, and both are under transcriptional regulation by the nuclear liver X receptor (LXR). Considerable evidence from genetic (using ABCA1 overexpression) and pharmacological (using synthetic LXR agonists) studies in AD mouse models suggests that increased levels of lipidated apoE can improve cognitive performance and, in some strains, can reduce amyloid burden. However, direct synthetic LXR ligands have hepatotoxic side effects that limit their clinical use. Here, we describe a set of small molecules, previously annotated as antagonists of the purinergic receptor, P2X7, which enhance ABCA1 expression and activity as well as apoE secretion, and are not direct LXR ligands. Furthermore, P2X7 is not required for these molecules to induce ABCA1 upregulation and apoE secretion, demonstrating that the ABCA1 and apoE effects are mechanistically independent of P2X7 inhibition. Hence, we have identified novel dual activity compounds that upregulate ABCA1 across multiple CNS cell types, including human astrocytes, pericytes, and microglia, through an indirect LXR mechanism and that also independently inhibit P2X7 receptor activity.

A Versatile and Convenient Synthesis of 34 S-Labeled Phosphorothioate Oligonucleotides.

A synthetic protocol for 34 S-labeled phosphorothioate oligonucleotides (PS ONs) was developed to facilitate MS-based assay analysis. This was enabled by a highly efficient, two-step, one-pot synthesis of 34 S-labeled phenylacetyl disulfide (34 S-PADS), starting from 34 S-enriched elemental sulfur (34 S8 ). 34 S-PADS was subsequently used for stable isotope labeling (SIL) of oligonucleotides containing a phosphorothioate backbone. The 34 S-SIL PS ONs are shown to retain the same melting temperature, antisense activity, and secondary structure as those of the corresponding unlabeled 32 S PS ONs.

Potency prediction of ß-secretase (BACE-1) inhibitors using density functional methods.

Scoring potency is a main challenge for structure based drug design. Inductive effects of subtle variations in the ligand are not possible to accurately predict by classical computational chemistry methods. In this study, the problem of predicting potency of ligands with electronic variations participating in key interactions with the protein was addressed. The potency was predicted for a large set of cyclic amidine and guanidine cores extracted from ß-secretase (BACE-1) inhibitors. All cores were of similar size and had equal interaction motifs but were diverse with respect to electronic substitutions. A density functional theory approach, in combination with a representation of the active site of a protein using only key residues, was shown to be predictive. This computational approach was used to guide and support drug design, within the time frame of a normal drug discovery design cycle.

Thermodynamic studies of ligand binding to the human homopentameric glycine receptor using isothermal titration calorimetry.

In this work, we describe a process for production of a Pichia pastoris strain which overproduces large quantities of the human glycine receptor. Subsequent purification yielded functional, uniform protein with expression yields of up to 5 mg per liter cell culture. As the wild-type protein is prone to proteolytic degradation, the labile sites were removed by mutagenesis resulting in an intracellular loop 2 deletion mutant with N-terminal modifications. This variant of the receptor is both stable during purification and storage on ice for up to a week as a complex with an antagonist. The quality of the protein is suitable for biophysical characterization and structural studies. The interaction of the agonist glycine and the antagonist strychnine with purified protein was analyzed by isothermal titration calorimetry. Strychnine binding is driven enthalpically with a K(D) of 138 ± 55 nM, a ΔH of -9708 ± 1195 cal/mol and a ΔS of -1.0 ± 4.1 cal/mol/K, whereas glycine binding is driven by entropy with a K(D) of 3.2 ± 0.8 µM, a ΔH of -2228 ± 1012 cal/mol and ΔS of 17.7 ± 2.8 cal/mol/K. Strychnine and glycine binding is competitive with a stoichiometry of one ligand molecule to one pentameric glycine receptor.

Optimised generation of iPSC-derived macrophages and dendritic cells that are functionally and transcriptionally similar to their primary counterparts.

Induced pluripotent stem cells (iPSC) offer the possibility to generate diverse disease-relevant cell types, from any genetic background with the use of cellular reprogramming and directed differentiation. This provides a powerful platform for disease modeling, drug screening and cell therapeutics. The critical question is how the differentiated iPSC-derived cells translate to their primary counterparts. Our refinement of a published differentiation protocol produces a CD14+ monocytic lineage at a higher yield, in a smaller format and at a lower cost. These iPSC-derived monocytes can be further differentiated into macrophages or dendritic cells (DC), both with similar morphological and functional profiles as compared to their primary counterparts. Transcriptomic analysis of iPSC-derived cells at different stages of differentiation as well as comparison to their blood-derived counterparts demonstrates a complete switch of iPSCs to cells expressing a monocyte, macrophage or DC specific gene profile. iPSC-derived macrophages respond to LPS treatment by inducing expression of classic macrophage pro-inflammatory response markers. Interestingly, though iPSC-derived DC show similarities to monocyte derived DC, they are more similar transcriptionally to a newly described subpopulation of AXL+ DC. Thus, our study provides a detailed and accurate profile of iPSC-derived monocytic lineage cells.

Axl receptor tyrosine kinase is a regulator of apolipoprotein E.

Alzheimer's disease (AD), the leading cause of dementia, is a chronic neurodegenerative disease. Apolipoprotein E (apoE), which carries lipids in the brain in the form of lipoproteins, plays an undisputed role in AD pathophysiology. A high-throughput phenotypic screen was conducted using a CCF-STTG1 human astrocytoma cell line to identify small molecules that could upregulate apoE secretion. AZ7235, a previously discovered Axl kinase inhibitor, was identified to have robust apoE activity in brain microglia, astrocytes and pericytes. AZ7235 also increased expression of ATP-binding cassette protein A1 (ABCA1), which is involved in the lipidation and secretion of apoE. Moreover, AZ7235 did not exhibit Liver-X-Receptor (LXR) activity and stimulated apoE and ABCA1 expression in the absence of LXR. Target validation studies using AXL-/- CCF-STTG1 cells showed that Axl is required to mediate AZ7235 upregulation of apoE and ABCA1. Intriguingly, apoE expression and secretion was significantly attenuated in AXL-deficient CCF-STTG1 cells and reconstitution of Axl or kinase-dead Axl significantly restored apoE baseline levels, demonstrating that Axl also plays a role in maintaining apoE homeostasis in astrocytes independent of its kinase activity. Lastly, these effects may require human apoE regulatory sequences, as AZ7235 exhibited little stimulatory activity toward apoE and ABCA1 in primary murine glia derived from neonatal human APOE3 targeted-replacement mice. Collectively, we identified a small molecule that exhibits robust apoE and ABCA1 activity independent of the LXR pathway in human cells and elucidated a novel relationship between Axl and apoE homeostasis in human astrocytes.

Novel Chemical Series of 5-Lipoxygenase-Activating Protein Inhibitors for Treatment of Coronary Artery Disease.

5-Lipoxygenase (5-LO)-activating protein (FLAP) inhibitors have proven to attenuate 5-LO pathway activity and leukotriene production in human clinical trials. However, previous clinical candidates have been discontinued and the link between FLAP inhibition and outcome in inflammatory diseases remains to be established. We here describe a novel series of FLAP inhibitors identified from a screen of 10k compounds and the medicinal chemistry strategies undertaken to progress this series. Compound 4i showed good overall properties and a pIC50 hWBfree of 8.1 and an lipophilic ligand efficiency of 5.2. Target engagement for 4i was established in dogs using ex vivo measurement of leukotriene B4 (LTB4) levels in blood with good correlation to in vitro potency. A predicted human dose of 280 mg b.i.d. suggests a wide margin to any identified in vitro off-target effects and sufficient exposure to achieve an 80% reduction of LTB4 levels in humans. Compound 4i is progressed to preclinical in vivo safety studies.

Clinical characterization and the mutation spectrum in Swedish adenomatous polyposis families.

BACKGROUND: The dominantly inherited condition familial adenomatous polyposis (FAP) is caused by germline mutations in the APC gene. Finding the causative mutations has great implications for the families. Correlating the genotypes to the phenotypes could help to improve the diagnosis and follow-up of patients. METHODS: Mutation screening of APC and the clinical characterization of 96 unrelated FAP patients from the Swedish Polyposis Registry was performed. In addition to generally used mutation screening methods, analyses of splicing-affecting mutations and investigations of the presence of low-frequency mutation alleles, indicating mosaics, have been performed, as well as quantitative real-time polymerase chain reaction to detect lowered expression of APC. RESULTS: Sixty-one different APC mutations in 81 of the 96 families were identified and 27 of those are novel. We have previously shown that 6 of the 96 patients carried biallelic MUTYH mutations. The 9 mutation-negative cases all display an attenuated or atypical phenotype. Probands with a genotype (codon 1250-1464) predicting a severe phenotype had a median age at diagnosis of 21.8 (range, 11-49) years compared with 34.4 (range, 14-57) years among those with mutations outside this region (P < 0.017). Dense polyposis (> 1000) occurred in 75% of the probands with a severe phenotype compared with 30% in those with mutations outside this region. The morbidity in colorectal cancer among probands was 25% at a mean age of 37.5 years and 29% at a mean age of 46.6 years. CONCLUSION: Using a variety of mutation-detection techniques, we have achieved a 100% detection frequency in classical FAP. Probands with APC mutations outside codon 1250-1464, although exhibiting a less-severe phenotype, are at high risk of having a colorectal cancer at diagnosis indicating that age at diagnosis is as important as the severity of the disease for colorectal cancer morbidity.

Microbial drug efflux proteins of the major facilitator superfamily.

Drug efflux proteins are widespread amongst microorganisms, including pathogens. They can contribute to both natural insensitivity to antibiotics and to emerging antibiotic resistance and so are potential targets for the development of new antibacterial drugs. The design of such drugs would be greatly facilitated by knowledge of the structures of these transport proteins, which are poorly understood, because of the difficulties of obtaining crystals of quality. We describe a structural genomics approach for the amplified expression, purification and characterisation of prokaryotic drug efflux proteins of the 'Major Facilitator Superfamily' (MFS) of transport proteins from Helicobacter pylori, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Bacillus subtilis, Brucella melitensis, Campylobacter jejuni, Neisseria meningitides and Streptomyces coelicolor. The H. pylori putative drug resistance protein, HP1092, and the S. aureus QacA proteins are used as detailed examples. This strategy is an important step towards reproducible production of transport proteins for the screening of drug binding and for optimisation of crystallisation conditions to enable subsequent structure determination.

Nuclear accumulation of full-length and truncated adenomatous polyposis coli protein in tumor cells depends on proliferation.

The adenomatous polyposis coli (APC) tumor suppressor is a nucleocytoplasmic protein. The nuclear accumulation of APC was recently found to vary depending on cell density, suggesting that putative APC function(s) in the nucleus is controlled by the establishment of cell contacts. We report here that the density-dependent redistribution of APC between nucleus and cytoplasm prevails in 6/6 thyroid and colorectal carcinoma cell lines. Moreover, mutated APC lacking known nuclear localization sequences had the similar distribution pattern as the full-length protein. APC invariably accumulated in the nuclei of Ki-67 expressing cells, but was largely cytoplasmic when cell cycle exit was induced by serum starvation or at high cell density. APC colocalized with beta-catenin in the nucleus only in one cell line (SW480). Also, APC maintained a predominantly nuclear position in early confluent states when cytoplasmic beta-catenin was recruited to newly formed adherens-like junctions. The results indicate that nuclear targeting of APC is driven by cell cycle entry rather than altered cell-cell contact. The ability of C-terminally truncated APC to accumulate in the nucleus suggests that nuclear import signals other than NLS1(APC) and NLS2(APC) are functionally important. Residual function(s) of N-terminal APC fragments in tumor cells carrying APC mutations might be beneficial to tumor growth and survival.

Collection and characterisation of bacterial membrane proteins.

A general strategy for the amplified expression in Escherichia coli of membrane transport and receptor proteins from other bacteria is described. As an illustration we report the cloning of the putative alpha-ketoglutarate membrane transport gene from the genome of Helicobacter pylori, overexpression of the protein tagged with RGS(His)6 at the C-terminus, and its purification in mg quantities. The retention of structural and functional integrity was verified by circular dichroism spectroscopy and reconstitution of transport activity. This strategy for overexpression and purification is extended to additional membrane proteins from H. pylori and from other bacteria.

Identification of genomic deletions of the APC gene in familial adenomatous polyposis by two independent quantitative techniques.

Large deletions in the APC (adenomatous polyposis coli) gene, causing familial adenomatous polyposis (FAP), cannot easily be detected by conventional mutation-detection techniques. Therefore, we have developed two independent quantitative methods for the detection of large deletions, encompassing one or more exons, of APC. Multiplex ligation-dependent probe amplification (MLPA) is performed in one reaction for the initial quantification of all APC exon copy numbers. Subsequently, quantitative real-time PCR (QRT-PCR) is used to verify the results obtained in the MLPA reaction. The identification of a deletion of the whole APC gene in a patient with classical FAP is described. The mutation was detected with the two quantitative methods and further verified on chromosomal level by the use of FISH (fluorescence in situ hybridization) on metaphase spreads. Furthermore, a large deletion covering exons 11-13 of the APC gene was detected in two apparently unrelated families. This deletion was further verified and characterized with long-range PCR. The MLPA test ensures a sensitive high-throughput screening for large deletions of the APC gene and can easily be implemented in the diagnostic testing for FAP.