A selective inhibitor of histone deacetylase 3 prevents cognitive deficits and suppresses striatal CAG repeat expansions in Huntington's disease mice

Huntington's disease (HD) is a neurodegenerative disorder whose major symptoms include progressive motor and cognitive dysfunction. Cognitive decline is a critical quality of life concern for HD patients and families. The enzyme histone deacetylase 3 (HDAC3) appears to be important in HD pathology by negatively regulating genes involved in cognitive functions. Furthermore, HDAC3 has been implicated in the aberrant transcriptional patterns that help cause disease symptoms in HD mice. HDAC3 also helps fuel CAG repeat expansions in human cells, suggesting that HDAC3 may power striatal expansions in the HTT gene thought to drive disease progression. This multifaceted role suggests that early HDAC3 inhibition offers an attractive mechanism to prevent HD cognitive decline and to suppress striatal expansions. This hypothesis was investigated by treating HdhQ111 knock-in mice with the HDAC3-selective inhibitor RGFP966. Chronic early treatment prevented long-term memory impairments and normalized specific memory-related gene expression in hippocampus. Additionally, RGFP966 prevented corticostriatal-dependent motor learning deficits, significantly suppressed striatal CAG repeat expansions, partially rescued striatal protein marker expression and reduced accumulation of mutant huntingtin oligomeric forms. These novel results highlight RGFP966 as an appealing multiple-benefit therapy in HD that concurrently prevents cognitive decline and suppresses striatal CAG repeat expansions

Histone Deacetylase Complexes Promote Trinucleotide Repeat Expansions

Genetic analysis in budding yeast and in cultured human astrocytes reveals that specific histone deacetylase complexes accelerate expansion mutations in DNA triplet repeats

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

A selective inhibitor of histone deacetylase 3 prevents cognitive deficits and suppresses striatal CAG repeat expansions in Huntington's disease mice

Huntington's disease (HD) is a neurodegenerative disorder whose major symptoms include progressive motor and cognitive dysfunction. Cognitive decline is a critical quality of life concern for HD patients and families. The enzyme histone deacetylase 3 (HDAC3) appears to be important in HD pathology by negatively regulating genes involved in cognitive functions. Furthermore, HDAC3 has been implicated in the aberrant transcriptional patterns that help cause disease symptoms in HD mice. HDAC3 also helps fuel CAG repeat expansions in human cells, suggesting that HDAC3 may power striatal expansions in the HTT gene thought to drive disease progression. This multifaceted role suggests that early HDAC3 inhibition offers an attractive mechanism to prevent HD cognitive decline and to suppress striatal expansions. This hypothesis was investigated by treating HdhQ111 knock-in mice with the HDAC3-selective inhibitor RGFP966. Chronic early treatment prevented long-term memory impairments and normalized specific memory-related gene expression in hippocampus. Additionally, RGFP966 prevented corticostriatal-dependent motor learning deficits, significantly suppressed striatal CAG repeat expansions, partially rescued striatal protein marker expression and reduced accumulation of mutant huntingtin oligomeric forms. These novel results highlight RGFP966 as an appealing multiple-benefit therapy in HD that concurrently prevents cognitive decline and suppresses striatal CAG repeat expansions

Sialyltransferase inhibition leads to inhibition of tumor cell interactions with E-selectin, VCAM1, and MADCAM1, and improves survival in a human multiple myeloma mouse model.

Aberrant glycosylation resulting from altered expression of sialyltransferases, such as ST3 beta-galactoside alpha2-3-sialyltransferase 6, plays an important role in disease progression in multiple myeloma. Hypersialylation can lead to increased immune evasion, drug resistance, tumor invasiveness, and disseminated disease. In this study, we explore the in vitro and in vivo effects of global sialyltransferase inhibition on myeloma cells using the pan-sialyltransferase inhibitor 3Fax-Neu5Ac delivered as a peracetylated methyl ester pro-drug. Specifically, we show in vivo that 3Fax-Neu5Ac improves survival by enhancing bortezomib sensitivity in an aggressive mouse model of multiple myeloma. However, 3Fax-Neu5Ac treatment of multiple myeloma cells in vitro did not reverse bortezomib resistance conferred by bone marrow stromal cells. Instead, 3Fax-Neu5Ac significantly reduced interactions of myeloma cells with E-selectin, MADCAM1 and VCAM1, suggesting that reduced sialylation impairs extravasation and retention of myeloma cells in the bone marrow. Finally, we showed that 3Fax-Neu5Ac alters the post-translational modification of the α4 integrin, which may explain the reduced affinity of α4β1/α4β7 integrins for their counter-receptors. We propose that inhibiting sialylation may represent a valuable strategy to restrict myeloma cells from entering the protective bone marrow microenvironment, a niche in which they are normally protected from chemotherapeutic agents such as bortezomib. Thus, our work demonstrates that targeting sialylation to increase the ratio of circulating to bone marrow-resident multiple myeloma cells represents a new avenue that could increase the efficacy of other anti-myeloma therapies and holds great promise for future clinical applications

Chemical inhibition or RNAi knockdown of HDAC3 in human SVG-A cells suppresses expansions.

<p>(A) The genetic assay is essentially as described <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001257#pbio.1001257-Claassen1" target="_blank">[27]</a>. Cells were treated with either HDAC inhibitor <b>4b</b>, compound <b>3</b>, or DMSO only. Alternatively, siRNA was used with scrambled siRNA as a control. Expansions are scored using yeast as a biosensor, and total plasmid counts are monitored by bacterial transformation for enhanced sensitivity. (B) Expansion frequencies as a function of inhibitor dose, compared to DMSO-treated control cells. Blue, <b>4b</b>-treated; red, compound <b>3</b>-treated. Error bar, ±SEM; * <i>p</i><0.05 compared to DMSO-treated cells. Details in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001257#pbio.1001257.s011" target="_blank">Table S3</a>. (C) Expansion frequency after RNAi. Knockdown efficiency, judged by three independent immunoblots, averaged 76(±8)% for HDAC3 and 76(±2)% for HDAC1. Error bars, ±SEM; * <i>p</i><0.05 compared to scrambled control. Details in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001257#pbio.1001257.s011" target="_blank">Table S3</a>. (D) Expansion sizes, derived from PCR analysis. 21 genetically independent expansions for DMSO, 16 for <b>4b</b> (combined data from 10 µM and 20 µM treatments), 28 for scrambled siRNA, and 13 for HDAC3 siRNA. (E) Cell viability measured by nigrosin staining just prior to cell harvest. (F) Representative immunoblot of acetylated histone H4 and total histone H4 upon treatment with <b>4b</b>; data summary in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001257#pbio.1001257.s006" target="_blank">Figure S6</a>. (G) Expansion frequencies after RNAi against histone acetyltransferases. Error bars, ±SEM; * <i>p</i><0.05 compared to scrambled control.</p

Evidence that Rpd3L acts in trans to promote expansions.

<p>(A) <i>sin3</i> mutants suppress expansion rates when the TNR reporter is integrated at “hot” zone, <i>INO1</i> on chromosome X and a “cold” zone, <i>SPS2</i> on chromosome IV. Error bars, ±SEM; * <i>p</i><0.05 compared to wild type. (B, C) Chromatin immunoprecipitation using antibodies against pan-acetylated histone H4 or total H4. Underline indicates the TNR reporter integration site at <i>INO1</i> (B) or <i>SPS2</i> (C). Rand, control reporter with randomized sequence in place of triplet repeat. Error bars, ±SEM. Primer site details are provided in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001257#pbio.1001257.s008" target="_blank">Figure S8</a>. (D) Expansion rates in single or double mutants of <i>sae2</i>, <i>mre11</i>, <i>exo1</i>, and/or <i>sin3</i>. The reporter was (CTG)₂₀-<i>CAN1</i> integrated on chromosome II. Error bars, ±SEM; * <i>p</i><0.05 compared to wild type. Details for panels (A–D) are in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001257#pbio.1001257.s012" target="_blank">Table S4</a>. (E) Model for HDAC promotion of expansions in yeast. 1. Acetylated Sae2 (Ac-Sae2) is marked for degradation, but it is stabilized by deacetylation in an Rpd3L- and Hda1-dependent manner <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001257#pbio.1001257-Robert1" target="_blank">[32]</a>. The same HDACs may deacetylate other factors relevant to expansions, thereby stabilizing them or influencing their activities. The action of Rpd3L and Hda1 is counterbalanced by one or more HATs that await identification. 2. Sae2 along with another nuclease, Mre11, cleaves TNR DNA, possibly in a hairpin structure, to initiate the expansion pathway. 3. The cleaved TNR undergoes additional processing steps to complete the expansion.</p