Biology subjects

Andersen, R. J.

Publications and source records attributed to Andersen, R. J..

5 recordsLinked to original sources

bioRxiv2024

Ex vivo and in vivo HIV-1 latency reversal by Mukungulu, a protein kinase C-activating African medicinal plant extract

Current HIV latency reversing agents (LRAs) have had limited success in clinic, indicating the need for new strategies that can reactivate and/or eliminate HIV reservoirs. "Mukungulu," prepared from the bark of Croton megalobotrys Mull. Arg., is traditionally used for HIV/AIDS management in Northern Botswana despite containing an abundance of protein kinase C (PKC)-activating phorbol esters ("namushens"). Here we show that Mukungulu is tolerated in mice at up to 12.5 mg/kg while potently reversing latency in antiretroviral therapy (ART)-suppressed HIV-infected humanized mice at 5 mg/kg. In peripheral blood mononuclear cells (PBMC) and isolated CD4+ T-cells from ART-suppressed people living with HIV-1, 1 {micro}g/mL Mukungulu reverses latency on par with or superior to anti-CD3/CD28 positive control, as measured by HIV gag-p24 protein expression, where the magnitude of HIV reactivation in PBMC corresponds to intact proviral burden levels in CD4+ T-cells. Bioassay-guided fractionation identifies 5 namushen phorbol ester compounds that reactivate HIV expression, yet namushens alone do not match Mukungulus activity, suggesting additional enhancing factors. Together, these results identify Mukungulu as a robust natural LRA which may warrant inclusion in future LRA-based HIV cure and ART-free remission efforts.

microbiology↗

bioRxiv2023

Complete Synthesis and Stereochemical Assignment of Novel Curcuphenol Analogues Possessing Anti-Metastatic Cancer Biological Activity

For eons, turmeric and curcumin have been used as culinary spices and as traditional medicines and as vogue dietary supplements for a growing list of disorders, including arthritis, digestive disorders, respiratory infections, allergies, liver disease, depression and cancer. The activities of these spices are commonly attributed to curcuminoids; however, the medical applications of this class of compounds has been limited due to the low water solubility, chemical instability, acid lability, poor absorption, rapid catabolism by enzymes of the diverse curcuminoids contained in turmeric and curcumin extracts. Furthermore, identifying the bio-active curcuminoids with unique molecular entities responsible for specific medicinal benefit is at its infancy. To overcome these many issues and substantially advance this area of inquiry, we created a water-soluble achiral curcuphenol analogue and a water-soluble racemic analogue that have enhanced chemical characteristics and biological performance, and we subsequently demonstrated their ability to reverse the immune-escape phenotype, a process that enables tumours to hide from host immune responses and thereby provides tumours a significant growth advantage to metastatic tumours. The discovery that curcuphenols can reverse tumour immune-escape mechanisms and thereby reduce tumour growth, provides a rationale for the development of advanced dissecting nutraceuticals and bioceuticals for unique chemical entities as therapeutic building blocks to synthesize analogues with optimal chemical characteristics capable of harnessing the power of the immune system to extinguish metastatic cancers and beyond.

biochemistry↗

bioRxiv2020

Phospholipid flippases and Sfk1 are essential for the retention of ergosterol in the plasma membrane

Sterols are important lipid components of the plasma membrane (PM) in eukaryotic cells, but it is unknown how the PM retains sterols at a high concentration. Phospholipids are asymmetrically distributed in the PM, and phospholipid flippases play an important role in generating this phospholipid asymmetry. Here, we provide evidence that phospholipid flippases are essential for retaining ergosterol in the PM of yeast. A mutant in three flippases, Dnf1-Lem3, Dnf2-Lem3, and Dnf3-Crf1, and a membrane protein, Sfk1, showed a severe growth defect. We recently identified Sfk1 as a PM protein involved in phospholipid asymmetry. The PM of this mutant showed high permeability and low density, and many nutrient transporters failed to localize to the PM. Staining with the sterol probe filipin and the expression of a sterol biosensor revealed that ergosterol was not retained in the PM. Instead, ergosterol accumulated in an esterified form in lipid droplets. We propose that ergosterol is retained in the PM by the asymmetrical distribution of phospholipids and the action of Sfk1. Once phospholipid asymmetry is severely disrupted, sterols might be exposed on the cytoplasmic leaflet of the PM and actively transported to the endoplasmic reticulum by sterol transfer proteins.

cell biology↗

bioRxiv2020

Interleukin-10 and Small Molecule SHIP1 Allosteric Regulators Trigger Anti-Inflammatory Effects Through SHIP1/STAT3 Complexes

The anti-inflammatory actions of interleukin-10 (IL10) are thought to be mediated primarily by the STAT3 transcription factor, but pro-inflammatory cytokines such as interleukin-6 (IL6) also act through STAT3. We now report that IL10, but not IL6 signaling, induces formation of a complex between STAT3 and the inositol polyphosphate-5-phosphatase SHIP1 in macrophages. Both SHIP1 and STAT3 translocate to the nucleus in macrophages. Remarkably, sesquiterpenes of the Pelorol family we previously described as allosteric activators of SHIP1 phosphatase activity, could induce SHIP1/STAT3 complex formation in cells, and mimic the anti-inflammatory action of IL10 in a mouse model of colitis. Using crystallography and docking studies we identified a drug-binding pocket in SHIP1. Our studies reveal new mechanisms of action for both STAT3 and SHIP1, and provide a rationale for use of allosteric SHIP1-activating compounds which mimic the beneficial anti-inflammatory actions of IL10.

immunology↗

bioRxiv2018

Gentamicin B1 is not a minor gentamicin component with major nonsense mutation suppression activity

Nonsense mutations are single base substitutions that introduce a premature termination codon (PTC) preventing the formation of full-length protein. They are the causative mutations in about 10% of patients in a large number of rare genetic diseases. High concentrations of the antibiotic gentamicin can induce the incorporation of an amino acid at a PTC and formation of full-length protein, a process called PTC readthrough. Gentamicin is composed of several related aminoglycosides. We recently reported (doi/10.1073/pnas.1620982114) that the major gentamicin components that are responsible for its antibacterial activity showed weak to no PTC readthrough activity but that the minor component gentamicin B1 was a potent readthrough inducer. We have now determined that gentamicin B1 acquired from the sole supplier at the time the study was carried out was not gentamicin B1 but instead the closely related aminoglycoside G418. Gentamicin B1 recently became available from a second commercial source. Here, we provide nuclear magnetic resonance (NMR) assignment data for the two commercial compounds and verify only the second is indeed gentamicin B1. We show that gentamicin B1 lacks PTC readthrough activity in HDQ-P1 and DMS-114 cells homozygous for the TP53 R213X nonsense mutation, as well as in a cell-free translation assay.

biochemistry↗