PET imaging evidence of HDAC6 suppression in the amygdala across species in PTSD.

Histone deacetylases (HDACs), typically known for regulating gene expression, also play a major role in protein regulation outside of histone modification. Emerging evidence suggests the HDACs may be novel pharmacologic targets in complex disorders such as posttraumatic stress disorder (PTSD). Histone deacetylase 6 (HDAC6) regulates microtubule function and plays a role in stress-related cortisol signaling in serotonergic regions of the brain by maintaining the nuclear translocation of glucocorticoid receptors.

Assessment of test-retest reproducibility by [F]Bavarostat for PET imaging of HDAC6.

Background: Histone deacetylase 6 (HDAC6) is an enzyme pivotal for gene regulation, influencing cellular pathways through protein deacetylation. HDAC6 is a potential therapeutic target in diseases such as cancer and neurodegenerative disorders. Koole et al.

Greater Neuroimmune System Deficit in Women Than Men With Alcohol Use Disorder.

Background: Women who drink are more vulnerable than men to many of the consequences of alcohol use, including alcohol-related cancers, cardiovascular disease, liver cirrhosis, and immune system dysfunction. Acute alcohol triggers neuroimmune cells including microglia-the brain's resident immune cells. Excessive activation can contribute to neuronal dysfunction and alcohol-induced neurodegeneration.

Neuroglia in anxiety disorders.

Anxiety disorders are some of the most prevalent in the world and are extraordinarily debilitating to many individuals, costing millions in disability. One of the most disabling is posttraumatic stress disorder (Snijders et al., 2020).

The Structures, Functions, and Roles of Class III HDACs (Sirtuins) in Neuropsychiatric Diseases.

Over the past two decades, epigenetic regulation has become a rapidly growing and influential field in biology and medicine. One key mechanism involves the acetylation and deacetylation of lysine residues on histone core proteins and other critical proteins that regulate gene expression and cellular signaling. Although histone deacetylases (HDACs) have received significant attention, the roles of individual HDAC isoforms in the pathogenesis of psychiatric diseases still require further research.

Microglia-mediated neuroimmune suppression in PTSD is associated with anhedonia.

Dynamic brain immune function in individuals with posttraumatic stress disorder is rarely studied, despite evidence of peripheral immune dysfunction. Positron emission tomography brain imaging using the radiotracer [C]PBR28 was used to measure the 18-kDa translocator protein (TSPO), a microglial marker, at baseline and 3 h after administration of lipopolysaccharide (LPS), a potent immune activator. Data were acquired in 15 individuals with PTSD and 15 age-matched controls.

A Role for Histone Deacetylases in the Biology and Treatment of Post-Traumatic Stress Disorder: What Do We Know and Where Do We Go from Here?

Post-traumatic stress disorder is a prevalent disorder within the USA and worldwide with a yearly diagnosis rate of 2-4% and affecting women more than men. One of the primary methods for study of this stress disorder relies on animal models as there are few noninvasive methods and few replicated peripheral biomarkers for use in humans. One area of active research in psychiatric neuroscience is the field of epigenetics - how the chemical modifications of the genetic code regulate behavior.

Spatial and temporal dynamics of HDACs class IIa following mild traumatic brain injury in adult rats.

The fundamental role of epigenetic regulatory mechanisms involved in neuroplasticity and adaptive responses to traumatic brain injury (TBI) is gaining increased recognition. TBI-induced neurodegeneration is associated with several changes in the expression-activity of various epigenetic regulatory enzymes, including histone deacetylases (HDACs). In this study, PET/CT with 6-([F]trifluoroacetamido)-1- hexanoicanilide ([F]TFAHA) to image spatial and temporal dynamics of HDACs class IIa expression-activity in brains of adult rats subjected to a weight drop model of diffuse, non-penetrating, mild traumatic brain injury (mTBI).

Multimodal neuroimaging of gliomatosis cerebri: a case series of four patients.

In the latest World Health Organization classification of brain tumors, gliomatosis cerebri has been redefined to varying subsets of diffuse gliomas; however, the term is still used to describe gliomas with infiltrative growth into three or more cerebral lobes. These tumors are frequently misdiagnosed and difficult to treat due to their atypical presentation using structural imaging modalities including computed tomography and T1/T2-weighted magnetic resonance imaging (MRI). In this retrospective case series, we compared clinical MRI to amino acid positron emission tomography (PET) to assess the potential value of PET in the assessment of the extent of tumor involvement and in monitoring disease progression.

Noninvasive quantification of SIRT1 expression-activity and pharmacologic inhibition in a rat model of intracerebral glioma using 2-[F]BzAHA PET/CT/MRI.

Background: Several studies demonstrated that glioblastoma multiforme progression and recurrence is linked to epigenetic regulatory mechanisms. Sirtuin 1 (SIRT1) plays an important role in glioma progression, invasion, and treatment response and is a potential therapeutic target. The aim of this study is to test the feasibility of 2-[F]BzAHA for quantitative imaging of SIRT1 expression-activity and monitoring pharmacologic inhibition in a rat model of intracerebral glioma.

Molecular imaging HDACs class IIa expression-activity and pharmacologic inhibition in intracerebral glioma models in rats using PET/CT/(MRI) with [F]TFAHA.

HDAC class IIa enzymes (HDAC4, 5, 7, 9) are important for glioma progression, invasion, responses to TMZ and radiotherapy, and prognosis. In this study, we demonstrated the efficacy of PET/CT/(MRI) with [F]TFAHA for non-invasive and quantitative imaging of HDAC class IIa expression-activity in intracerebral 9L and U87-MG gliomas in rats. Increased accumulation of [F]TFAHA in 9L and U87-MG tumors was observed at 20 min post radiotracer administration with SUV of 1.

Molecular Imaging of Sirtuin1 Expression-Activity in Rat Brain Using Positron-Emission Tomography-Magnetic-Resonance Imaging with [F]-2-Fluorobenzoylaminohexanoicanilide.

Sirtuin 1 (SIRT1) is a class III histone deacetylase that plays significant roles in the regulation of lifespan, metabolism, memory, and circadian rhythms and in the mechanisms of many diseases. However, methods of monitoring the pharmacodynamics of SIRT1-targeted drugs are limited to blood sampling because of the invasive nature of biopsies. For the noninvasive monitoring of the spatial and temporal dynamics of SIRT1 expression-activity in vivo by PET-CT-MRI, we developed a novel substrate-type radiotracer, [F]-2-fluorobenzoylaminohexanoicanilide (2-[F]BzAHA).

A Novel Substrate Radiotracer for Molecular Imaging of SIRT2 Expression and Activity with Positron Emission Tomography.

Purpose: The purpose of this study was to develop a SIRT2-specific substrate-type radiotracer for non-invasive PET imaging of epigenetic regulatory processes mediated by SIRT2 in normal and disease tissues.

Procedures: A library of compounds containing tert-butyloxycarbonyl-lysine-aminomethylcoumarin backbone was derivatized with fluoroalkyl chains 3-16 carbons in length. SIRT2 most efficiently cleaved the myristoyl, followed by 12-fluorododecanoic and 10-fluorodecanoic groups (K/K 716.

Investigating carbohydrate based ligands for galectin-3 with docking and molecular dynamics studies.

Galectin-3 (Gal-3) is a carbohydrate binding protein that is overexpressed in several types of cancers, including pancreatic cancer, which makes it a good target for both imaging and therapeutic drug design. A ligand library specialized for F positron emission tomography (PET) has been investigated with molecular dynamics (MD) and free energy methods to determine the relative binding energies of various potential ligands. Our results suggest that traditional docking methods can give good results when complemented by molecular dynamics and free energy methods for these types of ligands.

Novel Histone Deacetylase Class IIa Selective Substrate Radiotracers for PET Imaging of Epigenetic Regulation in the Brain.

Histone deacetylases (HDAC's) became increasingly important targets for therapy of various diseases, resulting in a pressing need to develop HDAC class- and isoform-selective inhibitors. Class IIa deacetylases possess only minimal deacetylase activity against acetylated histones, but have several other client proteins as substrates through which they participate in epigenetic regulation. Herein, we report the radiosyntheses of the second generation of HDAC class IIa-specific radiotracers: 6-(di-fluoroacetamido)-1-hexanoicanilide (DFAHA) and 6-(tri-fluoroacetamido)-1-hexanoicanilide ([18F]-TFAHA).