Rosmarinic acid enhances CHO cell productivity and proliferation through activation of the unfolded protein response and the mTOR pathway.

Rosmarinic acid (RA) has gained attraction in bioprocessing as a media supplement to improve cellular proliferation and protein production. Here, we observe up to a two-fold increase in antibody production with RA-supplementation, and a concentration-dependent effect of RA on cell proliferation for fed-batch Chinese hamster ovary (CHO) cell cultures. Contrary to previously reported antioxidant activity, RA increased the reactive oxygen species (ROS) levels, stimulated endoplasmic reticulum (ER) stress, activated the unfolded protein response (UPR), and elicited DNA damage. Despite such stressful events, RA appeared to maintained cell health via mammalian target of rapamycin (mTOR) pathway activation; both mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2) were stimulated in RA-supplemented cultures. By reversing such mTOR pathway activity through either chemical inhibitor addition or siRNA knockdown of genes regulating the mTORC1 and mTORC2 complexes, antibody production, UPR signaling, and stress-induced DNA damage were reduced. Further, the proliferative effect of RA appeared to be regulated selectively by mTORC2 activation and have reproduced this observation by using the mTORC2 stimulator SC-79. Analogously, knockdown of mTORC2 strongly reduced X-box binding protein 1 (XBP1) splicing, which would be expected to reduce antibody folding and secretion, sugging that reduced mTORC2 would correlate with reduced antibody levels. The crosstalk between mTOR activation and UPR upregulation may thus be related directly to the enhanced productivity. Our results show the importance of the mTOR and UPR pathways in increasing antibody productivity, and suggest that RA supplementation may obviate the need for labor-intensive genetic engineering by directly activating pathways favorable to cell culture performance.

Use of single analytic tool to quantify both absolute N-glycosylation and glycan distribution in monoclonal antibodies.

Recombinant proteins represent almost half of the top selling therapeutics-with over a hundred billion dollars in global sales-and their efficacy and safety strongly depend on glycosylation. In this study, we showcase a simple method to simultaneously analyze N-glycan micro- and macroheterogeneity of an immunoglobulin G (IgG) by quantifying glycan occupancy and distribution. Our approach is linear over a wide range of glycan and glycoprotein concentrations down to 25 ng/mL. Additionally, we present a case study demonstrating the effect of small molecule metabolic regulators on glycan heterogeneity using this approach. In particular, sodium oxamate (SOD) decreased Chinese hamster ovary (CHO) glucose metabolism and reduced IgG glycosylation by 40% through upregulating reactive oxygen species (ROS) and reducing the UDP-GlcNAc pool, while maintaining a similar glycan profile to control cultures. Here, we suggest glycan macroheterogeneity as an attribute should be included in bioprocess screening to identify process parameters that optimize culture performance without compromising antibody quality.

Advances in nanodisc platforms for membrane protein purification.

Membrane scaffold protein nanodiscs (MSPNDs) are an invaluable tool for improving purified membrane protein (MP) stability and activity compared to traditional micellar methods, thus enabling an increase in high-resolution MP structures, particularly in concert with cryogenic electron microscopy (cryo-EM) approaches. In this review we highlight recent advances and breakthroughs in MSPND methodology and applications. We also introduce and discuss saposin-lipoprotein nanoparticles (salipros) and copolymer nanodiscs which have recently emerged as authentic MSPND alternatives. We compare the advantages and disadvantages of MSPNDs, salipros, and copolymer nanodisc technologies to highlight potential opportunities for using each platform for MP purification and characterization.

The Interplay between GSK3ß and Tau Ser262 Phosphorylation during the Progression of Tau Pathology.

Tau hyperphosphorylation has been linked directly to the formation of toxic neurofibrillary tangles (NFTs) in tauopathies, however, prior to NFT formation, the sequence of pathological events involving tau phosphorylation remains unclear. Here, the effect of glycogen synthase kinase 3ß (GSK3ß) on tau pathology was examined independently for each step of transcellular propagation; namely, tau intracellular aggregation, release, cellular uptake and seeding activity. We find that overexpression of GSK3ß-induced phosphorylated 0N4R tau led to a higher level of tau oligomerization in SH-SY5Y neuroblastoma cells than wild type 0N4R, as determined by several orthogonal assays. Interestingly, the presence of GSK3ß also enhanced tau release. Further, we demonstrated that cells endocytosed more monomeric tau protein when pre-phosphorylated by GSK3ß. Using an extracellular vesicle (EVs)-assisted tau neuronal delivery system, we show that exosomal GSK3ß-phosphorylated tau, when added to differentiated SH-SY5Y cells, induced more efficient tau transfer, showing much higher total tau levels and increased tau aggregate formation as compared to wild type exosomal tau. The role of a primary tau phosphorylation site targeted by microtubule-affinity regulating kinases (MARKs), Ser262, was tested by pseudo-phosphorylation using site-directed mutagenesis to aspartate (S262D). S262D tau overexpression significantly enhanced tau release and intracellular tau accumulation, which were concurrent with the increase of pathological states of tau, as determined by immunodetection. Importantly, phosphorylation-induced tau accumulation was augmented by co-transfecting S262D tau with GSK3ß, suggesting a possible interplay between Ser262 phosphorylation and GSK3ß activity in tau pathology. Lastly, we found that pre-treatment of cells with amyloid-ß (Aß) further tau phosphorylation and accumulation when Ser262 pre-phosphorylation was present, suggesting that S262 may be a primary mediator of Aß-induced tau toxicity. These findings provide a potential therapeutic target for treating tau-related disorders by targeting specific phospho-tau isoforms and further elucidate the GSK3ß-mediated pathological seeding mechanisms.

Progress toward rapid, at-line N-glycosylation detection and control for recombinant protein expression.

Proteins continue to represent a large fraction of the therapeutics market, reaching over a hundred billion dollars in market size globally. One key feature of protein modification that can affect both structure and function is the addition of glycosylation following protein folding, leading to regulatory requirements for the accurate assessment of protein attributes, including glycan structures. The non-template-driven, innately heterogeneous N-glycosylation process thus requires accurate detection to robustly generate protein therapies. A challenge exists in the timely detection of protein glycosylation without labor-intensive manipulation. In this article, we discuss progress toward N-glycoprotein control, focusing on novel control strategies and the advancement of rapid, high-throughput analysis methods.

Cholesterol Dependent Activity of the Adenosine A2A Receptor Is Modulated via the Cholesterol Consensus Motif.

BACKGROUND: Membrane cholesterol dysregulation has been shown to alter the activity of the adenosine A2A receptor (A2AR), a G protein-coupled receptor, thereby implicating cholesterol levels in diseases such as Alzheimer's and Parkinson's. A limited number of A2AR crystal structures show the receptor interacting with cholesterol, as such molecular simulations are often used to predict cholesterol interaction sites. METHODS: Here, we use experimental methods to determine whether a specific interaction between amino acid side chains in the cholesterol consensus motif (CCM) of full length, wild-type human A2AR, and cholesterol modulates activity of the receptor by testing the effects of mutational changes on functional consequences, including ligand binding, G protein coupling, and downstream activation of cyclic AMP. RESULTS AND CONCLUSIONS: Our data, taken with previously published studies, support a model of receptor state-dependent binding between cholesterol and the CCM, whereby cholesterol facilitates both G protein coupling and downstream signaling of A2AR.

Risankizumab as maintenance therapy for moderately to severely active Crohn's disease: results from the multicentre, randomised, double-blind, placebo-controlled, withdrawal phase 3 FORTIFY maintenance trial.

BACKGROUND: There is a great unmet need for new therapeutics with novel mechanisms of action for patients with Crohn's disease. The ADVANCE and MOTIVATE studies showed that intravenous risankizumab, a selective p19 anti-interleukin (IL)-23 antibody, was efficacious and well tolerated as induction therapy. Here, we report the efficacy and safety of subcutaneous risankizumab as maintenance therapy. METHODS: FORTIFY is a phase 3, multicentre, randomised, double-blind, placebo-controlled, maintenance withdrawal study across 273 clinical centres in 44 countries across North and South America, Europe, Oceania, Africa, and the Asia-Pacific region that enrolled participants with clinical response to risankizumab in the ADVANCE or MOTIVATE induction studies. Patients in ADVANCE or MOTIVATE were aged 16-80 years with moderately to severely active Crohn's disease. Patients in the FORTIFY substudy 1 were randomly assigned again (1:1:1) to receive either subcutaneous risankizumab 180 mg, subcutaneous risankizumab 360 mg, or withdrawal from risankizumab to receive subcutaneous placebo (herein referred to as withdrawal [subcutaneous placebo]). Treatment was given every 8 weeks. Patients were stratified by induction dose, post-induction endoscopic response, and clinical remission status. Patients, investigators, and study personnel were masked to treatment assignments. Week 52 co-primary endpoints were clinical remission (Crohn's disease activity index [CDAI] in the US protocol, or stool frequency and abdominal pain score in the non-US protocol) and endoscopic response in patients who received at least one dose of study drug during the 52-week maintenance period. Safety was assessed in patients receiving at least one dose of study medication. This study is registered with ClinicalTrials.gov, NCT03105102. FINDINGS: 712 patients were initially assessed and, between April 9, 2018, and April 24, 2020, 542 patients were randomly assigned to either the risankizumab 180 mg group (n=179), the risankizumab 360 mg group (n=179), or the placebo group (n=184). Greater clinical remission and endoscopic response rates were reached with 360 mg risankizumab versus placebo (CDAI clinical remission was reached in 74 (52%) of 141 patients vs 67 (41%) of 164 patients, adjusted difference 15% [95% CI 5-24]; stool frequency and abdominal pain score clinical remission was reached in 73 (52%) of 141 vs 65 (40%) of 164, adjusted difference 15% [5-25]; endoscopic response 66 (47%) of 141 patients vs 36 (22%) of 164 patients, adjusted difference 28% [19-37]). Higher rates of CDAI clinical remission and endoscopic response (but not stool frequency and abdominal pain score clinical remission [p=0·124]) were also reached with risankizumab 180 mg versus withdrawal (subcutaneous placebo; CDAI clinical remission reached in 87 [55%] of 157 patients, adjusted difference 15% [95% CI 5-24]; endoscopic response 74 [47%] of 157, adjusted difference 26% [17-35]). Results for more stringent endoscopic and composite endpoints and inflammatory biomarkers were consistent with a dose-response relationship. Maintenance treatment was well tolerated. Adverse event rates were similar among groups, and the most frequently reported adverse events in all treatment groups were worsening Crohn's disease, arthralgia, and headache. INTERPRETATION: Subcutaneous risankizumab is a safe and efficacious treatment for maintenance of remission in patients with moderately to severely active Crohn's disease and offers a new therapeutic option for a broad range of patients by meeting endpoints that might change the future course of disease. FUNDING: AbbVie.

Risankizumab as induction therapy for Crohn's disease: results from the phase 3 ADVANCE and MOTIVATE induction trials.

BACKGROUND: Risankizumab, an interleukin (IL)-23 p19 inhibitor, was evaluated for safety and efficacy as induction therapy in patients with moderately to severely active Crohn's disease. METHODS: ADVANCE and MOTIVATE were randomised, double-masked, placebo-controlled, phase 3 induction studies. Eligible patients aged 16-80 years with moderately to severely active Crohn's disease, previously showing intolerance or inadequate response to one or more approved biologics or conventional therapy (ADVANCE) or to biologics (MOTIVATE), were randomly assigned to receive a single dose of intravenous risankizumab (600 mg or 1200 mg) or placebo (2:2:1 in ADVANCE, 1:1:1 in MOTIVATE) at weeks 0, 4, and 8. We used interactive response technology for random assignment, with stratification by number of previous failed biologics, corticosteroid use at baseline, and Simple Endoscopic Score for Crohn's disease (SES-CD). All patients and study personnel (excluding pharmacists who prepared intravenous solutions) were masked to treatment allocation throughout the study. Coprimary endpoints were clinical remission (defined by Crohn's disease activity index [CDAI] or patient-reported outcome criteria [average daily stool frequency and abdominal pain score]) and endoscopic response at week 12. The intention-to-treat population (all eligible patients who received at least one dose of study drug in the 12-week induction period) was analysed for efficacy outcomes. Safety was assessed in all patients who received at least one dose of study drug. Both trials were registered on ClinicalTrials.gov, NCT03105128 (ADVANCE) and NCT03104413 (MOTIVATE), and are now complete. FINDINGS: Participants were enrolled between May 10, 2017, and Aug 24, 2020 (ADVANCE trial), and Dec 18, 2017 and Sept 9, 2020 (MOTIVATE trial). In ADVANCE, 931 patients were assigned to either risankizumab 600 mg (n=373), risankizumab 1200 mg (n=372), or placebo (n=186). In MOTIVATE, 618 patients were assigned to risankizumab 600 mg (n=206), risankizumab 1200 mg (n=205), or placebo (n=207). The primary analysis population comprised 850 participants in ADVANCE and 569 participants in MOTIVATE. All coprimary endpoints at week 12 were met in both trials with both doses of risankizumab (p values ≤0·0001). In ADVANCE, CDAI clinical remission rate was 45% (adjusted difference 21%, 95% CI 12-29; 152/336) with risankizumab 600 mg and 42% (17%, 8-25; 141/339) with risankizumab 1200 mg versus 25% (43/175) with placebo; stool frequency and abdominal pain score clinical remission rate was 43% (22%, 14-30; 146/336) with risankizumab 600 mg and 41% (19%, 11-27; 139/339) with risankizumab 1200 mg versus 22% (38/175) with placebo; and endoscopic response rate was 40% (28%, 21-35; 135/336) with risankizumab 600 mg and 32% (20%, 14-27; 109/339) with risankizumab 1200 mg versus 12% (21/175) with placebo. In MOTIVATE, CDAI clinical remission rate was 42% (22%, 13-31; 80/191) with risankizumab 600 mg and 40% (21%, 12-29; 77/191) with risankizumab 1200 mg versus 20% (37/187) with placebo; stool frequency and abdominal pain score clinical remission rate was 35% (15%, 6-24; 66/191) with risankizumab 600 mg and 40% (20%, 12-29; 76/191) with risankizumab 1200 mg versus 19% (36/187) with placebo; and endoscopic response rate was 29% (18%, 10-25; 55/191) with risankizumab 600 mg and 34% (23%, 15-31; 65/191) with risankizumab 1200 mg versus 11% (21/187) with placebo. The overall incidence of treatment-emergent adverse events was similar among the treatment groups in both trials. Three deaths occurred during induction (two in the placebo group [ADVANCE] and one in the risankizumab 1200 mg group [MOTIVATE]). The death in the risankizumab-treated patient was deemed unrelated to the study drug. INTERPRETATION: Risankizumab was effective and well tolerated as induction therapy in patients with moderately to severely active Crohn's disease. FUNDING: AbbVie.

Higher vs Standard Adalimumab Induction and Maintenance Dosing Regimens for Treatment of Ulcerative Colitis: SERENE UC Trial Results.

BACKGROUND & AIMS: SERENE UC (Study of a Novel Approach to Induction and Maintenance Dosing With Adalimumab in Patients With Moderate to Severe Ulcerative Colitis) evaluated the efficacy of higher adalimumab induction and maintenance dose regimens in patients with ulcerative colitis. METHODS: This phase 3, double-blind, randomized trial included induction and maintenance studies, with a main study (ex-Japan) and Japan substudy. Eligible patients (18-75 years, full Mayo score 6-12, centrally read endoscopy subscore 2-3) were randomized 3:2 to higher induction regimen (adalimumab 160 mg at weeks 0, 1, 2, and 3) or standard induction regimen (160 mg at week 0 and 80 mg at week 2); all received 40 mg at weeks 4 and 6. At week 8, all patients were rerandomized 2:2:1 (main study) to 40 mg every week (ew), 40 mg every other week (eow), or exploratory therapeutic drug monitoring; or 1:1 (Japan substudy) to 40 mg ew or 40 mg eow maintenance regimens. RESULTS: In the main study, 13.3% vs 10.9% of patients receiving the higher induction regimen vs standard induction regimen achieved clinical remission (full Mayo score ≤2 with no subscore >1) at week 8 (induction primary end point; P = .265); among week-8 responders, 39.5% vs 29.0% receiving 40 mg ew vs 40 mg eow achieved clinical remission at week 52 (maintenance primary end point; P = .069). In the integrated (main + Japan) population, 41.1% vs 30.1% of week-8 responders receiving 40 mg ew vs 40 mg eow achieved clinical remission at week 52 (nominal P = .045). Safety profiles were comparable between dosing regimens. CONCLUSION: Although primary end points were not met, a >10% absolute difference in clinical remission was demonstrated with higher adalimumab maintenance dosing. Higher dosing regimens were generally well tolerated and consistent with the known safety profile of adalimumab in ulcerative colitis. CLINICALTRIALS: gov, Number: NCT002209456.

Higher vs Standard Adalimumab Induction Dosing Regimens and Two Maintenance Strategies: Randomized SERENE CD Trial Results.

BACKGROUND & AIMS: Dose-optimization strategies for biologic therapies in Crohn's disease (CD) are not well established. The SERENE CD (Study of a Novel Approach to Induction and Maintenance Dosing With Adalimumab in Patients With Moderate to Severe Crohn's Disease) trial evaluated higher vs standard adalimumab induction dosing and clinically adjusted (CA) vs therapeutic drug monitoring (TDM) maintenance strategies in patients with moderately to severely active CD. METHODS: In this phase 3, randomized, double-blind, multicenter trial, eligible adults (Crohn's Disease Activity Index score of 220-450, endoscopic evidence of mucosal inflammation, and previous failure of standard therapies) were randomized to higher induction regimen (adalimumab 160 mg at weeks 0, 1, 2, and 3; n = 308) or standard induction regimen (adalimumab 160 mg at week 0 and 80 mg at week 2; n = 206) followed by 40 mg every other week from week 4 onward. Co-primary end points included clinical remission at week 4 and endoscopic response at week 12. At week 12, patients were re-randomized to maintenance therapy optimized by Crohn's Disease Activity Index and C-reactive protein (CA; n = 92) or serum adalimumab concentrations and/or clinical criteria (TDM; n = 92); exploratory end points were evaluated at week 56. RESULTS: Similar proportions of patients receiving higher induction regimen and standard induction regimen achieved clinical remission at week 4 (44% in both; P = .939) and endoscopic response at week 12 (43% vs 39%, respectively, P = .462). Week 56 efficacy was similar between CA and TDM. Safety profiles were comparable between dosing regimens. CONCLUSIONS: Higher induction regimen was not superior to standard induction regimen, and CA and TDM maintenance strategies were similarly efficacious. Adalimumab therapy was well tolerated, and no new safety concerns were identified. (ClinicalTrials.gov, Number: NCT02065570).

Heparan Sulfate Proteoglycans (HSPGs) Serve as the Mediator Between Monomeric Tau and Its Subsequent Intracellular ERK1/2 Pathway Activation.

The conversion of soluble tau protein to insoluble, hyperphosphorylated neurofibrillary tangles (NFTs) is a major hallmark leading to neuronal death observed in neurodegenerative tauopathies. Unlike NFTs, the involvement of monomeric tau in the progression of tau pathology has been less investigated. Using live-cell confocal microscopy and flow cytometry, we demonstrate that soluble 0N4R monomers were rapidly endocytosed by SH-SY5Y and C6 glioma cells via actin-dependent macropinocytosis. Further, cellular endocytosis of monomeric tau has been demonstrated to be HSPG-dependent, as shown in C6 glial cells with genetic knockouts of xylosyltransferase-1-a key enzyme in HSPG synthesis-with a reduced level of tau uptake. Tau internalization subsequently triggers ERK1/2 activation and therefore, the upregulation of IL-6 and IL-1ß. The role of ERK1/2 in regulating the levels of pro-inflammatory gene transcripts was confirmed by inhibiting the MEK-ERK1/2 signaling pathway, which led to the attenuated IL-6 and IL-1ß expressions but not that of TNF-α. Moreover, as a key regulator of tau internalization, LRP1 (low-density lipoprotein receptor-related protein 1) levels were downregulated in response to monomeric tau added to C6 cells, while it was upregulated in HSPG-deficient cells, suggesting that the involvement of LRP1 in tau uptake depends on the presence of HSPGs on the cell surface. The subsequent LRP1 knockdown experiment we performed shows that LRP1 deficiency leads to an attenuated propensity for tau uptake and further elevated IL-6 gene expression. Collectively, our data suggest that tau has multiple extracellular binding partners that mediate its internalization through distinct mechanisms. Additionally, this study demonstrates the important role of both HSPGs and LRP1 in regulating cellular immune responses to tau protein monomers, providing a novel target for alleviating the neuroinflammatory environment before the formation of neurofibrillary tangles.

Challenges for design of aggregation-resistant variants of granulocyte colony-stimulating factor.

Non-native protein aggregation is a long-standing issue in pharmaceutical biotechnology. A rational design approach was used in order to identify variants of recombinant human granulocyte colony-stimulating factor (rhG-CSF) with lower aggregation propensity at solution conditions that are typical of commercial formulation. The approach used aggregation-prone-region (APR) predictors to select single amino acid substitutions that were predicted to decrease intrinsic aggregation propensity (IAP). The results of static light scattering temperature-ramps and chemical unfolding experiments demonstrated that none of the selected variants exhibited improved aggregation resistance, and the apparent conformational stability of each variant was lower than that of WT. Aggregation studies under partly denaturing conditions suggested that the IAP of at least one variant remained unaltered. Overall, this study highlights a general challenge in designing aggregation resistance for proteins, due to the need to accurately predict both APRs and conformational stability.

Critical Molecular and Cellular Contributors to Tau Pathology.

Tauopathies represent a group of neurodegenerative diseases including Alzheimer's disease (AD) that are characterized by the deposition of filamentous tau aggregates in the brain. The pathogenesis of tauopathies starts from the formation of toxic 'tau seeds' from hyperphosphorylated tau monomers. The presence of specific phosphorylation sites and heat shock protein 90 facilitates soluble tau protein aggregation. Transcellular propagation of pathogenic tau into synaptically connected neuronal cells or adjacent glial cells via receptor-mediated endocytosis facilitate disease spread through the brain. While neuroprotective effects of glial cells-including phagocytotic microglial and astroglial phenotypes-have been observed at the early stage of neurodegeneration, dysfunctional neuronal-glial cellular communication results in a series of further pathological consequences as the disease progresses, including abnormal axonal transport, synaptic degeneration, and neuronal loss, accompanied by a pro-inflammatory microenvironment. Additionally, the discovery of microtubule-associated protein tau (MAPT) gene mutations and the strongest genetic risk factor of tauopathies-an increase in the presence of the ε2 allele of apolipoprotein E (ApoE)-provide important clues to understanding tau pathology progression. In this review, we describe the crucial signaling pathways and diverse cellular contributors to the progression of tauopathies. A systematic understanding of disease pathogenesis provides novel insights into therapeutic targets within altered signaling pathways and is of great significance for discovering effective treatments for tauopathies.

Characterization of binding kinetics of A2AR to Gαs protein by surface plasmon resonance.

Because of their surface localization, G protein-coupled receptors (GPCRs) are often pharmaceutical targets as they respond to a variety of extracellular stimuli (e.g., light, hormones, small molecules) that may activate or inhibit a downstream signaling response. The adenosine A2A receptor (A2AR) is a well-characterized GPCR that is expressed widely throughout the human body, with over 10 crystal structures determined. Truncation of the A2AR C-terminus is necessary for crystallization as this portion of the receptor is long and unstructured; however, previous work suggests shortening of the A2AR C-terminus from 412 to 316 amino acids (A2AΔ316R) ablates downstream signaling, as measured by cAMP production, to below that of constitutive full-length A2AR levels. As cAMP production is downstream of the first activation event-coupling of G protein to its receptor-investigating that first step in activation is important in understanding how the truncation effects native GPCR function. Here, using purified receptor and Gαs proteins, we characterize the association of A2AR and A2AΔ316R to Gαs with and without GDP or GTPγs using surface plasmon resonance (SPR). Gαs affinity for A2AR was greatest for apo-Gαs, moderately affected in the presence of GDP and nearly completely ablated by the addition of GTPγs. Truncation of the A2AR C-terminus (A2AΔ316R) decreased the affinity of the unliganded receptor for Gαs by ∼20%, suggesting small changes to binding can greatly impact downstream signaling.

The Specificity of Downstream Signaling for A1 and A2AR Does Not Depend on the C-Terminus, Despite the Importance of This Domain in Downstream Signaling Strength.

Recent efforts to determine the high-resolution crystal structures for the adenosine receptors (A1R and A2AR) have utilized modifications to the native receptors in order to facilitate receptor crystallization and structure determination. One common modification is a truncation of the unstructured C-terminus, which has been utilized for all the adenosine receptor crystal structures obtained to date. Ligand binding for this truncated receptor has been shown to be similar to full-length receptor for A2AR. However, the C-terminus has been identified as a location for protein-protein interactions that may be critical for the physiological function of these important drug targets. We show that variants with A2AR C-terminal truncations lacked cAMP-linked signaling compared to the full-length receptor constructs transfected into mammalian cells (HEK-293). In addition, we show that in a humanized yeast system, the absence of the full-length C-terminus affected downstream signaling using a yeast MAPK response-based fluorescence assay, though full-length receptors showed native-like G-protein coupling. To further study the G protein coupling, we used this humanized yeast platform to explore coupling to human-yeast G-protein chimeras in a cellular context. Although the C-terminus was essential for Gα protein-associated signaling, chimeras of A1R with a C-terminus of A2AR coupled to the A1R-specific Gα (i.e., Gαi1 versus Gαs). This surprising result suggests that the C-terminus is important in the signaling strength, but not specificity, of the Gα protein interaction. This result has further implications in drug discovery, both in enabling the experimental use of chimeras for ligand design, and in the cautious interpretation of structure-based drug design using truncated receptors.

Efficacy and safety of adalimumab in Chinese patients with moderately to severely active Crohn's disease: results from a randomized trial.

BACKGROUND AND AIMS: Efficacy of adalimumab in Crohn's disease (CD) has not been shown in China. The aim of this study was to evaluate the efficacy and safety of adalimumab in Chinese patients with CD. METHODS: This 26-week, multicenter, phase III study evaluated patients with moderately to severely active CD and elevated high-sensitivity C-reactive protein (⩾3 mg/l) who were naïve to anti-tumor necrosis factor therapy. Patients were randomized to double-blind adalimumab 160/80 mg at weeks 0/2 and 40 mg at weeks 4/6 or placebo at weeks 0/2 followed by blinded adalimumab 160/80 mg at weeks 4/6. At week 8, all patients received open-label 40 mg adalimumab every other week through week 26. The primary endpoint was clinical remission [CD activity index (CDAI) <150] at week 4. Clinical remission at week 26 was assessed in week-8 responders (decrease in CDAI ⩾70 points at week 8 from baseline) and compared with a clinically meaningful threshold of 30%. Adverse events (AEs) were recorded throughout the study. RESULTS: At baseline, 205 patients were enrolled, with mean [standard deviation (SD)] age of 32.9 (9.9) years and CD duration of 2.7 (3.0) years. At week 4, 38/102 patients (37%) receiving adalimumab and 7/103 (7%) receiving placebo (p < 0.001) achieved clinical remission. Among week-8 responders, 93/144 (65%) achieved clinical remission at week 26 (p < 0.001). No unexpected AEs and no malignancies, active tuberculosis, or deaths were reported. CONCLUSIONS: Adalimumab induced and maintained remission in Chinese patients with CD. Safety results were consistent with the known safety profile of adalimumab. CLINICALTRIALSGOV IDENTIFIER: NCT02499783.

Functional Expression of Adenosine A3 Receptor in Yeast Utilizing a Chimera with the A2AR C-Terminus.

The adenosine A3 receptor (A3R) is the only adenosine receptor subtype to be overexpressed in inflammatory and cancer cells and therefore is considered a novel and promising therapeutic target for inflammatory diseases and cancer. Heterologous expression of A3R at levels to allow biophysical characterization is a major bottleneck in structure-guided drug discovery efforts. Here, we apply protein engineering using chimeric receptors to improve expression and activity in yeast. Previously we had reported improved expression and trafficking of the chimeric A1R variant using a similar approach. In this report, we constructed chimeric A3/A2AR comprising the N-terminus and transmembrane domains from A3R (residues 1-284) and the cytoplasmic C-terminus of the A2AR (residues 291-412). The chimeric receptor showed approximately 2-fold improved expression with a 2-fold decreased unfolded protein response when compared to wild type A3R. Moreover, by varying culture conditions such as initial cell density and induction temperature a further 1.7-fold increase in total receptor yields was obtained. We observed native-like coupling of the chimeric receptor to Gai-Gpa1 in engineered yeast strains, activating the downstream, modified MAPK pathway. This strategy of utilizing chimeric receptor variants in yeast thus provides an exciting opportunity to improve expression and activity of "difficult-to-express" receptors, expanding the opportunity for utilizing yeast in drug discovery.

Media supplementation for targeted manipulation of monoclonal antibody galactosylation and fucosylation.

Monoclonal antibodies are critically important biologics as the largest class of molecules used to treat cancers, rheumatoid arthritis, and other chronic diseases. Antibody glycosylation is a critical quality attribute that has ramifications for patient safety and physiological efficacy-one that can be modified by such factors as media formulation and process conditions during production. Using a design-of-experiments approach, we examined the effect of 2-F-peracetyl fucose (2FP), uridine, and galactose on cell growth and metabolism, titer, and gene expression of key glycosylation-related proteins, and report how the glycoform distribution changed from Days 4 to 7 in a batch process used for IgG1 production from Chinese hamster ovary cells. We observed major glycosylation changes upon supplement addition, where the addition of 2FP decreased antibody fucosylation by up to 48%, galactose addition increased galactosylation by up to 21%, and uridine addition decreased fucosylation and increased galactosylation by 6% and 2%, respectively. Despite having major effects on glycosylation, neither galactose nor 2FP significantly affected cell culture growth, metabolism, or titer. Uridine improved peak cell densities by 23% but also reduced titer by ∼30%. The supplements caused significant changes in gene expression by Day 4 of the cultures where 2FP addition significantly reduced fucosyltransferase 8 and nucleotide sugar transporter gene expression (by ∼2-fold), and uridine addition significantly increased expression of UDP-GlcNAcT (SLC35A3) and B4GALT1-6 genes (by 1.5-3-fold). These gene expression data alongside glycosylation, metabolic, and growth data improve our understanding of the cellular mechanisms affected by media supplementation and suggest approaches for modifying antibody glycosylation in antibody production processes.

Nuclear translocation of the unliganded glucocorticoid receptor is influenced by membrane fluidity, but not A2AR agonism.

Epidemiological evidence suggests that chronic consumption of caffeine, a non-selective antagonist of adenosine A2AR receptors (A2AR), can be neuroprotective in a number of age-related neurodegenerative disorders including Alzheimer's disease. A growing body of work shows that this neuroprotection may act via a synergistic interaction with the glucocorticoid receptor (GR) and its associated genetic response elements. Therefore, we hypothesized that A2AR signaling may directly stimulate glucocorticoid receptor translocation via downstream signaling elements within the cell. Surprisingly, we found no effect of A2AR agonism on GR translocation in the absence of steroid. As expected, membrane-bound dexamethasone was capable of stimulating full GR translocation, albeit at a slower rate. This non-liganded translocation was unaffected by A2AR ligands, providing strong evidence that GR translocation occurs independently of activation of A2ARs. To identify other potential mechanisms of translocation, membrane fluidity was increased significantly by benzyl alcohol, which also induced full nuclear translocation of the GR, but unlike the membrane-bound dexamethasone, benzyl alcohol did result in transcriptional upregulation of GR-dependent genes. Taken together, our data shows that the unliganded GR is sensitive to changes in membrane state and can be transcriptionally active.