Druglike small molecules with photoswitchable bioactivity—photopharmaceuticals—allow biologists to perform studies with exquisitely precise and reversible, spatial and temporal control over critical ...biological systems inaccessible to genetic manipulation. The photoresponsive pharmacophores disclosed have been almost exclusively azobenzenes, which has limited the structural and substituent scope of photopharmacology. More detrimentally, for azobenzene reagents, it is not researchers’ needs for adapted experimental tools, but rather protein binding site sterics, that typically force whether the trans (dark) or cis (lit) isomer is the more bioactive. We now present the rational design of HOTubs, the first hemithioindigo‐based pharmacophores enabling photoswitchable control over endogenous biological activity in cellulo. HOTubs optically control microtubule depolymerisation and cell death in unmodified mammalian cells. Notably, we show how the asymmetry of hemithioindigos allows a priori design of either Z‐ or E‐ (dark‐ or lit)‐toxic antimitotics, whereas the corresponding azobenzenes are exclusively lit‐toxic. We thus demonstrate that hemithioindigos enable an important expansion of the substituent and design scope of photopharmacological interventions for biological systems.
Switch me off, switch me on: The first use of the hemithioindigo scaffold as a photoswitchable inhibitor pharmacophore is reported for the preparation of photopharmaceuticals to control endogenous cytoskeleton structure and cell cycle. Hemithioindigos allow a priori design of either Z‐ or E‐ (dark‐ or lit‐) bioactives, so they may address the problem of undesirable dark activity in the chemistry of cellular photopharmaceuticals.
Hemithioindigo is a promising molecular photoswitch that has only recently been applied as a photoswitchable pharmacophore for control over bioactivity in cellulo. Uniquely, in contrast to other ...photoswitches that have been applied to biology, the pseudosymmetric hemithioindigo scaffold has allowed the creation of both dark-active and lit-active photopharmaceuticals for the same binding site by a priori design. However, the potency of previous hemithioindigo photopharmaceuticals has not been optimal for their translation to other biological models.
Inspired by the structure of tubulin-inhibiting indanones, we created hemithioindigo-based indanone-like tubulin inhibitors (
) and optimised their cellular potency as antimitotic photopharmaceuticals. These
feature reliable and robust visible-light photoswitching and high fatigue resistance. The use of the hemithioindigo scaffold also permitted us to employ a
-hydroxyhemistilbene motif, a structural feature which is denied to most azobenzenes due to the negligibly short lifetimes of their metastable
-isomers, which proved crucial to enhancing the potency and photoswitchability. The
were ten times more potent than previously reported hemithioindigo photopharmaceutical antimitotics in a series of cell-free and cellular assays, and allowed robust photocontrol over tubulin polymerisation, microtubule (MT) network structure, cell cycle, and cell survival.
represent a powerful addition to the growing toolbox of photopharmaceutical reagents for MT cytoskeleton research. Additionally, as the hemithioindigo scaffold allows photoswitchable bioactivity for substituent patterns inaccessible to the majority of current photopharmaceuticals, wider adoption of the hemithioindigo scaffold may significantly expand the scope of cellular and in vivo targets addressable by photopharmacology.
Cilia are evolutionarily conserved organelles that can be found on virtually every cell. They appear as hair-like structures emanating from the cellular surface either as single or as bundles of ...cilia. There, they sense external stimuli and translate them into intracellular signals. Motile cilia beat for the generation of locomotion of unicellular organisms or fluid flow in certain body cavities of vertebrate organisms. Defects in cilia are detrimental and account for the development of ciliopathies, one of the fastest-growing family of afflictions. In the past decade, membrane lipids, such as cholesterol and phosphoinositides, have emerged as essential elements in both the signal transduction via cilia and the building of cilia itself. Here, we summarize the current knowledge on the impact of cholesterol and phosphoinositides on cilium biology.
We report the first cellular application of the emerging near‐quantitative photoswitch pyrrole hemithioindigo, by rationally designing photopharmaceutical PHTub inhibitors of the cytoskeletal protein ...tubulin. PHTubs allow simultaneous visible‐light imaging and photoswitching in live cells, delivering cell‐precise photomodulation of microtubule dynamics, and photocontrol over cell cycle progression and cell death. This is the first acute use of a hemithioindigo photopharmaceutical for high‐spatiotemporal‐resolution biological control in live cells. It additionally demonstrates the utility of near‐quantitative photoswitches, by enabling a dark‐active design to overcome residual background activity during cellular photopatterning. This work opens up new horizons for high‐precision microtubule research using PHTubs and shows the cellular applicability of pyrrole hemithioindigo as a valuable scaffold for photocontrol of a range of other biological targets.
Pyrrole hemithioindigos can be near‐quantitatively photoisomerised by the laser wavelengths available on confocal microscopes. The first pyrrole hemithioindigo‐based photopharmaceuticals, PHTubs, which are photoswitchable tubulin inhibitors, have been developed. PHTubs optically inhibit microtubule dynamics in live cells with single‐cell, second‐scale spatiotemporal precision, with both lit‐active and dark‐active compounds demonstrated in action.
We report the first cellular application of the emerging near‐quantitative photoswitch pyrrole hemithioindigo, by rationally designing photopharmaceutical PHTub inhibitors of the cytoskeletal protein ...tubulin. PHTubs allow simultaneous visible‐light imaging and photoswitching in live cells, delivering cell‐precise photomodulation of microtubule dynamics, and photocontrol over cell cycle progression and cell death. This is the first acute use of a hemithioindigo photopharmaceutical for high‐spatiotemporal‐resolution biological control in live cells. It additionally demonstrates the utility of near‐quantitative photoswitches, by enabling a dark‐active design to overcome residual background activity during cellular photopatterning. This work opens up new horizons for high‐precision microtubule research using PHTubs and shows the cellular applicability of pyrrole hemithioindigo as a valuable scaffold for photocontrol of a range of other biological targets.
Pyrrole hemithioindigos can be near‐quantitatively photoisomerised by the laser wavelengths available on confocal microscopes. The first pyrrole hemithioindigo‐based photopharmaceuticals, PHTubs, which are photoswitchable tubulin inhibitors, have been developed. PHTubs optically inhibit microtubule dynamics in live cells with single‐cell, second‐scale spatiotemporal precision, with both lit‐active and dark‐active compounds demonstrated in action.
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Dynamic maintenance of cell polarity is essential for development and physiology. Here we combine experiments and modeling to elucidate mechanisms that maintain cortical polarity in the C. elegans ...zygote. We show that polarity is dynamically stabilized by two coupled cross-inhibitory feedback loops: one involves the oligomeric scaffold PAR-3 and the kinase PAR-1, and the other involves CDC-42 and its putative GAP CHIN-1. PAR-3 and CDC-42 are both required locally to recruit PAR-6/PKC-3, which inhibits PAR-1 (shown previously) and inhibits local growth/accumulation of CHIN-1 clusters. Conversely, PAR-1 inhibits local accumulation of PAR-3 oligomers, while CHIN-1 inhibits CDC-42 (shown previously), such that either PAR-1 or CHIN-1 can prevent recruitment of PAR-6/PKC-3, but loss of both causes complete loss of polarity. Ultrasensitive dependence of CHIN-1 cluster growth on PAR-6/PKC-3 endows this core circuit with bistable dynamics, while transport of CHIN-1 clusters by cortical flow can stabilize the AP boundary against diffusive spread of PAR-6/PKC-3.
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•Zygotic polarity is stabilized by two redundant cross-inhibitory feedback loops•PAR-1 opposes PAR-3 clusters; PAR-6/PKC-3 oppose CHIN-1 clusters•Threshold dependence of CHIN-1 cluster growth on PAR-6/PKC-3 yields bistable dynamics•Cortical transport of CHIN-1 and PAR-3 clusters stabilizes AP boundary position
Sailer et al. show that in the C. elegans zygote, polarity is maintained by two redundant cross-inhibitory loops, both involving dynamically clustered polarity proteins. Threshold dependence of cluster growth on opposing kinases stabilizes complementary cortical domains, while cortical transport of clustered proteins can stabilize boundary position against diffusive drift.
Summary Background Angiogenesis is a target in the treatment of ovarian cancer. Nintedanib, an oral triple angiokinase inhibitor of VEGF receptor, platelet-derived growth factor receptor, and ...fibroblast growth factor receptor, has shown activity in phase 2 trials in this setting. We investigated the combination of nintedanib with standard carboplatin and paclitaxel chemotherapy in patients with newly diagnosed advanced ovarian cancer. Methods In this double-blind phase 3 trial, chemotherapy-naive patients (aged 18 years or older) with International Federation of Gynecology and Obstetrics (FIGO) IIB–IV ovarian cancer and upfront debulking surgery were stratified by postoperative resection status, FIGO stage, and planned carboplatin dose. Patients were randomly assigned (2:1) via an interactive voice or web-based response system to receive six cycles of carboplatin (AUC 5 mg/mL per min or 6 mg/mL per min) and paclitaxel (175 mg/m2 ) in addition to either 200 mg of nintedanib (nintedanib group) or placebo (placebo group) twice daily on days 2–21 of every 3-week cycle for up to 120 weeks. Patients, investigators, and independent radiological reviewers were masked to treatment allocation. The primary endpoint was investigator-assessed progression-free survival analysed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov , number NCT01015118. Findings Between Dec 9, 2009, and July 27, 2011, 1503 patients were screened and 1366 randomly assigned by nine study groups in 22 countries: 911 to the nintedanib group and 455 to the placebo group. 486 (53%) of 911 patients in the nintedanib group experienced disease progression or death compared with 266 (58%) of 455 in the placebo group. Median progression-free survival was significantly longer in the nintedanib group than in the placebo group (17·2 months 95% CI 16·6–19·9 vs 16·6 months 13·9–19·1; hazard ratio 0·84 95% CI 0·72–0·98; p=0·024). The most common adverse events were gastrointestinal (diarrhoea: nintedanib group 191 21% of 902 grade 3 and three <1% grade 4 vs placebo group nine 2% of 450 grade 3 only) and haematological (neutropenia: nintedanib group 180 20% grade 3 and 200 (22%) grade 4 vs placebo group 90 20% grade 3 and 72 16% grade 4; thrombocytopenia: 105 12% and 55 6% vs 21 5% and eight 2%; anaemia: 108 12% and 13 1% vs 26 6% and five 1%). Serious adverse events were reported in 376 (42%) of 902 patients in the nintedanib group and 155 (34%) of 450 in the placebo group. 29 (3%) of 902 patients in the nintedanib group experienced serious adverse events associated with death compared with 16 (4%) of 450 in the placebo group, including 12 (1%) in the nintedanib group and six (1%) in the placebo group with a malignant neoplasm progression classified as an adverse event by the investigator. Drug-related adverse events leading to death occurred in three patients in the nintedanib group (one without diagnosis of cause; one due to non-drug-related sepsis associated with drug-related diarrhoea and renal failure; and one due to peritonitis) and in one patient in the placebo group (cause unknown). Interpretation Nintedanib in combination with carboplatin and paclitaxel is an active first-line treatment that significantly increases progression-free survival for women with advanced ovarian cancer, but is associated with more gastrointestinal adverse events. Future studies should focus on improving patient selection and optimisation of tolerability. Funding Boehringer Ingelheim.
Treatment options to address the hyponatremia induced by the syndrome of inappropriate antidiuresis (SIAD) are inadequate. The sodium glucose cotransporter 2 (SGLT2) inhibitor empagliflozin promotes ...osmotic diuresis
urinary glucose excretion and therefore, might offer a novel treatment option for SIAD.
In this double-blind, randomized trial, we recruited 88 hospitalized patients with SIAD-induced hyponatremia <130 mmol/L at the University Hospital Basel from September 2016 until January 2019 and assigned patients to receive, in addition to standard fluid restriction of <1000 ml/24 h, a once-daily dose of oral empagliflozin or placebo for 4 days. The primary end point was the absolute change in plasma sodium concentration after 4 days of treatment. Secondary end points included predisposing factors for treatment response and safety of the intervention.
Of the 87 patients who completed the trial, 43 (49%) received treatment with empagliflozin, and 44 (51%) received placebo. Baseline plasma sodium concentrations were similar for the two groups (median 125.5 mmol/L for the empaflozin group and median 126 mmol/L for the placebo group). Patients treated with empagliflozin had a significantly higher increase of median plasma sodium concentration compared with those receiving placebo (10 versus 7 mmol/L, respectively;
=0.04). Profound hyponatremia (<125 mmol/L) and lower baseline osmolality levels increased the likelihood of response to treatment with empagliflozin. Treatment was well tolerated, and no events of hypoglycemia or hypotension occurred among those receiving empagliflozin.
Among hospitalized patients with SIAD treated with fluid restriction, those who received empagliflozin had a larger increase in plasma sodium levels compared with those who received placebo. This finding indicates that empagliflozin warrants further study as a treatment for the disorder.
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