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Muscle Atrophy: Counteracting Muscle Atrophy on Earth and in Space via Nanofluidics Delivery of Formoterol
No full textSkeletal muscle atrophy is a critical health problem that affects quality of life and increases morbidity and mortality. At present, exercise training remains the only intervention and pharmaceutical treatments remain elusive. Formoterol (FMT), a β2‐adrenergic receptor agonist, has emerged as a potential therapeutic by triggering skeletal muscle anabolism with daily dosing. Here, the efficacy of sustained FMT release is investigated via a subcutaneously implanted nanofluidic delivery system (nF) to prevent muscle wasting. Pharmacokinetics of nF‐mediated sustained FMT delivery (nF‐FMT) in healthy mice is assessed for 56 days, which demonstrates an anabolic effect on skeletal muscles. Using a hind limb suspension unloading mouse model, it is shown that nF‐FMT treatment attenuates soleus mass loss in comparison to control mice. Further, the very first study of an implantable drug delivery device in microgravity in vivo is launched. The microgravity environment aboard the International Space Station is leveraged to assess the atrophy prevention capability of nF‐FMT in mice for 29 and 55 days. Muscle hypertrophy is observed in both ground control and spaceflight mice treated with nF‐FMT compared to their respective vehicle controls. Overall, the nF system is presented as a viable platform for sustained delivery of FMT for therapeutic intervention of skeletal muscle atrophy
Targeting interleukin-4 to the arthritic joint
No full textAnti-inflammatory cytokines are a promising class of therapeutics for treatment of rheumatoid arthritis (RA) but their use is currently limited by a rapid clearance and systemic toxicity. Interleukin-4 is a small molecular weight cytokine with potential for RA therapy. To increase its pharmacokinetic features, we engineered a murine IL4 conjugate by incorporating an unnatural amino acid through genetic codon expansion to which PEG-folate as targeting moiety and PEG as control were site-specifically bound. Both IL4 conjugates retained bioactivity and induced primary murine macrophage polarization into an alternatively activated (M2) related phenotype. The PEGylated conjugates had a terminal half-life of about four hours in healthy mice. We showed that both conjugates successfully accumulated into arthritic joints in an antigen-induced arthritis (AIA) mouse model as assessed by non-invasive fluorescence imaging. The modular nature of the IL4 conjugate chemistry presented herein facilitates easy adaption of PEG chain length and targeting moieties to further improvement of half-life and targeting function for future efficacy studies
Nidufexor (LMB763), a Novel FXR Modulator for the Treatment of Nonalcoholic Steatohepatitis
No full textFarnesoid X receptor (FXR) agonists are emerging as important potential therapeutics for the treatment of nonalcoholic steatohepatitis (NASH) patients as they exert positive effects on multiple aspects of the disease. FXR agonists reduce lipid accumulation in the liver, hepatocellular inflammation, hepatic injury and fibrosis. While there are currently no approved therapies for NASH, the bile acid-derived FXR agonist obeticholic acid (OCA; 6-ethyl chenodeoxycholic acid) has shown promise in clinical studies. Previously, we have described the discovery of tropifexor (LJN452), the most potent non-bile acid FXR agonist currently in clinical investigation. Here, we describe the discovery of a novel chemical series of non-bile acid FXR agonists based on a tricyclic dihydrochromenopyrazole core from which emerged nidufexor (LMB763), a compound with partial FXR agonistic activity in vitro and FXR-dependent gene modulation in vivo. Nidufexor has advanced to Phase 2 human clinical trials in patients with NASH and diabetic nephropathy
Adhesion-GPCR Gpr116 (ADGRF5) is a Regulator of Urine Acidification and Surface Expression of the Vacuolar-type H+-ATPase in Renal α-Intercalated Cells
No full textThe G protein-coupled receptor (GPCR) superfamily is among the largest in the human genome. Their diversity and nearly universal expression underlie their significance in many physiologic processes. GPCRs are a common target of pharmaceutical drug development, and uncovering the function of understudied GPCRs in the kidney represents a wealth of untapped therapeutic potential. We previously identified Gpr116, an adhesion-class GPCR, as one of the most highly expressed GPCRs in the kidney. In the present study, we confirm the localization of Gpr116 to the luminal membrane of acid-secreting α-intercalated cells (αICs) in the nephron using both imaging and functional studies, where we demonstrate in situ receptor activation using an agonist peptide unique to Gpr116. Additionally, kidney-specific knockout (KO) of Gpr116 caused a significant reduction to urine pH. Notably, the loss of acid in the urine is accompanied by a small, but significant, increase in blood pH, and a small, but significant, decrease in pCO2 compared to wild-type littermates. Results from transmission electron micrographs show greater accumulation of V-ATPase proton pumps at the surface of αICs in KO mice, suggesting a possible role for Gpr116 in the regulation of V-ATPase trafficking. We conclude that loss of Gpr116 from the nephron causes a primary loss of acid in the urine which results in a mild metabolic alkalosis (“renal tubular alkalosis”) due to reabsorption of HCO3- by αICs. This study establishes a significant physiologic role of the previously understudied Gpr116 in the murine kidney and demonstrates the scientific potential of future investigations into novel GPCRs
Reimplementing Unirep in JAX
No full textUniRep is a recurrent neural network model
trained on 24 million protein sequences,
and has shown utility in protein engineering.
The original model, however, has rough spots in its implementation,
and a convenient API is not available for certain tasks.
To rectify this, we reimplemented the model in JAX/NumPy,
achieving near-100X speedups in forward pass performance,
and implemented a convenient API for specialized tasks.
In this article, we wish to document our model reimplementation process
with the goal of educating others interested in learning
how to dissect a deep learning model,
and engineer it for robustness and ease of use
Symmetric Geminal Bisphosphinic Acids RR´C[P(CH3)(O)OH]2 - NMR and Analytical Studies
No full textFour bisphosphinic acids RR´C[P(CH3)(O)OH]2 are characterized by 1H, 13C{1H}, and 31P{1H} NMR data. H3C-P-C-P-CH3 skeletons give rise to [A3X]2 spin systems. Some algebraic equations are derived for manual analysis of [A3X]2 spectra. HR NMR data for heteroaromatic substituents R in RC(H)[P(CH3)(O)OH]2 are reported. Dissociation constants and ion-specific chemical shifts dP of CH3C(OH)[P(CH3)(O)OH]2 are determined by 31{1H} NMR controlled titrations of 2a
Cell size homeostasis is maintained by a circuitry involving a CDK4-determined target size that programs the cell size-dependent activation of p38
No full textWhile molecules that promote the growth of animal cells have been identified, the following question remains: How are growth promoting pathways regulated to specify a characteristic size for each of the different cell types? In 1975, Hartwell and Nurse suggested that in eukaryotes, cell size is determined by size checkpoints – mechanisms that restrict cell cycle progression from cells that are smaller than their target size. Curiously, such checkpoint mechanisms imply a conceptual distinction between a cell’s actual size and cell’s target size. In the present study, we materialize this conceptual distinction by describing experimental assays that discriminately quantify a cell’s target size value. With these assays, we show that a cell’s size and target size are distinct phenotypes that are subject to different upstream regulators. While mTORC1 promotes growth in cell size, our data suggests that a cell’s target size value is regulated by other pathways including FGFR3, ROCK2, and CDK4. For example, while rapamycin (an mTORC1 inhibitor) decreases cell size, rapamycin does not change the target size that is required for the G1/S transition. The CDK4/Rb pathway has been previously proposed as a putative regulator of target size. Yet, in lacking experimental means that discriminate perturbations of cell growth from perturbations that reprogram target size, such claims on target size were not validated. To investigate the functions of CDK4 in target size determination, we used genetic and chemical means to ‘dial’ higher and lower levels of CDK4 activity. These measurements identified functions of CDK4 on target size that are distinct from other G1 CDKs. Using C. elegans, we further demonstrate that these influences of CDK4 on size determination function in vivo. Finally, we propose a model whereby mTORC1, p38, and CDK4 cooperate in a manner that is analogous to the function of a thermostat. While mTORC1 promotes cellular growth as prompted by p38, CDK4 is analogous to the thermostat dial that sets the critical target size associated with cell size homeostasis
Bioanalytical Challenges in Support of Complex Modalities of Antibody-Based Therapeutics
No full textAntibody-based therapeutic classes are evolving from monoclonal antibodies to antibody derivatives with complex structures to achieve advanced therapeutic effect. These antibody derivatives may contain multiple functional domains and are often vulnerable to in vivo biotransformation. Understanding the pharmacokinetics of these antibody derivatives requires a sophisticated bioanalytical approach to carefully characterize the whole drug and each functional domain with respect to quantity, functionality enabled by biotransformation, and corresponding immune responses. Ligand binding assays and liquid chromatography-mass spectrometry assays are predominantly used in bioanalytical support of monoclonal antibodies and are continuously used for antibody derivatives such as antibody drug conjugate and bispecific antibodies. However, they become increasingly cumbersome in coping with increased complexity of drug modality and associated biotransformation. In this mini-review, we examined the current pharmacokinetic assays in the literature for antibody drug conjugate and bispecific antibodies, and presented our view of promising bioanalytical technologies to address the distinct bioanalytical needs of complex modalities
Methamphetamine Enhances HIV-1 Replication in CD4 T-Cells via a Novel IL-1β Auto-Regulatory Loop.
No full textMethamphetamine (Meth) abuse is a worldwide public health problem and contributes to HIV-1 pathobiology and poor adherence to anti-retroviral therapies. Specifically, Meth is posited to alter molecular mechanisms to provide a more conducive environment for HIV-1 replication and spread. Enhanced expression of inflammatory cytokines, such as Interleukin-1β (IL-1β), has been shown to be important for HIV-1 pathobiology. In addition, microRNAs (miRNAs) play integral roles in fine-tuning the innate immune response. Notably, the effects of Meth abuse on miRNA expression are largely unknown. We studied the effects of Meth on IL-1β and miR-146a, a well-characterized member of the innate immune signaling network. We found that Meth induces miR-146a and triggers an IL-1β auto-regulatory loop to modulate innate immune signaling in CD4 T-cells. We also found that Meth enhances HIV-1 replication via IL-1 signaling. Our results indicate that Meth activates an IL-1β feedback loop to alter innate immune pathways and favor HIV-1 replication. These observations offer a framework for designing targeted therapies in HIV-infected, Meth using hosts
Recent progress on phenotype-based discovery of dengue inhibitors
No full textDengue fever is the world’s most prevalent mosquito-borne viral disease caused by the four serotypes of dengue viruses, which are widely spread throughout tropical and sub-tropical countries. There has been an urgent need to identify an effective and safe dengue inhibitor as a therapeutic and a prophylactic agent for dengue fever. Most clinically approved antiviral drugs for the treatment of human immunodeficiency syndrome-1 (HIV-1) and hepatitis C virus (HCV) target virally encoded enzymes such as protease or polymerase. Inhibitors of these enzymes were typically identified by target-based screening followed by optimization via structure-based design. However, due to the lack of success to date of research efforts to identify dengue protease and polymerase inhibitors, alternative strategies for anti-dengue drug discovery need to be considered. As a complementary approach to the target-based drug discovery, phenotypic screening is a strategy often used in identification of new chemical starting points with novel mechanism of action in the area of infectious diseases such as antibiotics, antivirals, and anti-parasitic agents. This article overviews recent reports of dengue phenotypic screens, and discusses phenotype-based hit-to-lead chemistry optimizations. Challenges and outlook of dengue phenotype-based lead discovery are discussed at the end of this article