Acute pharmacological degradation of Helios destabilizes regulatory T cells.

The zinc-finger transcription factor Helios is critical for maintaining the identity, anergic phenotype and suppressive activity of regulatory T (Treg) cells. While it is an attractive target to enhance the efficacy of currently approved immunotherapies, no existing approaches can directly modulate Helios activity or abundance. Here, we report the structure-guided development of small molecules that recruit the E3 ubiquitin ligase substrate receptor cereblon to Helios, thereby promoting its degradation. Pharmacological Helios degradation destabilized the anergic phenotype and reduced the suppressive activity of Treg cells, establishing a route towards Helios-targeting therapeutics. More generally, this study provides a framework for the development of small-molecule degraders for previously unligandable targets by reprogramming E3 ligase substrate specificity.

Vaginal Hormone Therapy for Conditions of the Lower Urinary Tract.

PURPOSE OF REVIEW: Up to half of postmenopausal women experience genitourinary symptoms secondary to hormone deficiency, and there is little consensus on the use of vaginal hormone therapy (VHT) for lower urinary tract symptoms (LUTS) in these patients. This is a review of the scientific literature in the last decade evaluating the use of VHT for disorders of the lower urinary tract including overactive bladder (OAB), stress urinary incontinence (SUI), recurrent urinary tract infections (UTI), and interstitial cystitis/bladder pain syndrome (ICS/BPS). RECENT FINDINGS: Vaginal estrogen therapy improves OAB symptoms in postmenopausal women, but results are mixed when VHT is used in combination with other treatments. There is inconclusive or limited data for the use of VHT to treat SUI and IC/BPS. Vaginal estrogen and prasterone (DHEA) therapies have demonstrated efficacy as treatment modalities for patients who experience recurrent UTIs. VHT preparations show efficacy for the treatment of certain LUTS and can be considered in carefully selected patients when clinically indicated.

Structure-Guided Design of a "Bump-and-Hole" Bromodomain-Based Degradation Tag.

Chemical biology tools to modulate protein levels in cells are critical to decipher complex biology. Targeted protein degradation offers the potential for rapid and dose-dependent protein depletion through the use of protein fusion tags toward which protein degraders have been established. Here, we present a newly developed protein degradation tag BRD4BD1L94V along with the corresponding cereblon (CRBN)-based heterobifunctional degrader based on a "bump-and-hole" approach. The resulting compound XY-06-007 shows a half-degradation concentration (DC50, 6 h) of 10 nM against BRD4BD1L94V with no degradation of off-targets, as assessed by whole proteome mass spectrometry, and demonstrates suitable pharmacokinetics for in vivo studies. We demonstrate that BRD4BD1L94V can be combined with the dTAG approach to achieve simultaneous degrader-mediated depletion of their respective protein fusions. This orthogonal system complements currently available protein degradation tags and enables investigation into the consequences resulting from rapid degradation of previously undruggable disease codependencies.

Tubulin Resists Degradation by Cereblon-Recruiting PROTACs.

Dysregulation of microtubules and tubulin homeostasis has been linked to developmental disorders, neurodegenerative diseases, and cancer. In general, both microtubule-stabilizing and destabilizing agents have been powerful tools for studies of microtubule cytoskeleton and as clinical agents in oncology. However, many cancers develop resistance to these agents, limiting their utility. We sought to address this by developing a different kind of agent: tubulin-targeted small molecule degraders. Degraders (also known as proteolysis-targeting chimeras (PROTACs)) are compounds that recruit endogenous E3 ligases to a target of interest, resulting in the target's degradation. We developed and examined several series of α- and ß-tubulin degraders, based on microtubule-destabilizing agents. Our results indicate, that although previously reported covalent tubulin binders led to tubulin degradation, in our hands, cereblon-recruiting PROTACs were not efficient. In summary, while we consider tubulin degraders to be valuable tools for studying the biology of tubulin homeostasis, it remains to be seen whether the PROTAC strategy can be applied to this target of high clinical relevance.