Histone 3.3 Participates in a Self-Sustaining Cascade of Apoptosis That Contributes to the Progression of Chronic Obstructive Pulmonary Disease

Abstract

Rationale: Shifts in the gene expression of nuclear protein in chronic obstructive pulmonary disease (COPD), a progressive disease that is characterized by extensive lung inflammation and apoptosis, are common; however, the extent of the elevation of the core histones, which are the major components of nuclear proteins and their consequences in COPD, has not been characterized, which is important because extracellular histones are cytotoxic to endothelial and airway epithelial cells. Objectives: To investigate the role of extracellular histones in COPD disease progression. Methods: We analyzed the nuclear lung proteomes of ex-smokers with and without the disease. Further studies on the consequences of H3.3 were also performed. Measurements and Main Results: A striking finding was a COPDspecific eightfold increase of hyperacetylated histone H3.3. The hyperacetylation renders H3.3 resistant to proteasomal degradation despite ubiquitination; when combined with the reduction in proteasome activity that is known for COPD, this resistance helps account for the increased levels of H3.3. Using anti-H3 antibodies, we found H3.3 in the airway lumen, alveolar fluid, and plasma of COPD samples. H3.3 was cytotoxic to lung structural cells via a mechanism that involves the perturbation of Ca 21 homeostasis and mitochondrial toxicity. We used the primary human airway epithelial cells and found that the antibodies to either the C or N terminus of H3 could partially reverse H3.3 toxicity. Conclusions: Our data indicate that there is an uncontrolled positive feedback loop in which the damaged cells release acetylated H3.3, which causes more damage, adds H3.3 release, and contributes toward the disease progression.Keywords: chronic obstructive pulmonary disease; histone H3.3; acetylation; cytotoxicity; proteomicsThe prevalence of chronic obstructive pulmonary disease (COPD) is increasing in industrialized countries (1, 2). COPD is the third leading cause of death worldwide (3). In 2011, the CDC estimated that 15 million adults in the United States had COPD, which contributed to $49 billion in direct and indirect healthcare costs (4, 5). Disease management can relieve symptoms and prolong life, although there are no treatments to stop the disease progression, which ultimately results in death.Although the molecular pathophysiology that underlies COPD has not been established, it is known that the expression of proinflammatory molecules, lung cell death, and tissue remodeling play critical roles (2, 6-8). Shifts in transcription factor activation and epigenetic markers, such as altered histone acetylation, are associated with changes in signaling proteins upstream of regulatory genes and in the assembly of nuclear chromatin complexes (9, 10). Core histones H2A, H2B, H3, H4 and their variants are key components of nuclear chromatin, the scaffolding that controls interactions between DNA with transcription factors and RNA polymerase, thereby regulating gene expression (11). Post-translational modification of histones causes chromatin ...

Cigarette Smoke Induces Distinct Histone Modifications in Lung Cells: Implications for the Pathogenesis of COPD and Lung Cancer

“…In this study, we determined the novel histone acetylation and methylation marks in histones H3 and H4 caused by CS exposure in vitro and in vivo due to its involvement in DNA damage/repair, pro-inflammatory gene activation, genomic instability and cellular senescence in a site-specific manner 45–49, 61, 62 . A recent study showed that extracellular, degradation-resistant, hyperacetylated histone H3.3 was elevated in lung of patients with COPD 31 . We and others have shown that human lung epithelial cells and mouse lung exposed to cigarette smoke causes histones H3 and H4 modifications limited to specific residues (e.g.…”

“…Furthermore, chromatin forms the extracellular trap protein components in neutrophils, particularly histones, which cause host cell cytotoxicity leading to the destruction of lung tissue 29 . It has been shown that circulating histones are mediators of trauma-associated lung injury 30 and are involved in apoptosis in lung cells 31 . Due to lack of evidence on the role of histone modifications in the pathogenesis of chronic lung diseases 13 , there is a need to study site-specific histone modifications using the rapidly growing mass spectrometry (MS) field.…”

Excessive caloric intake acutely causes oxidative stress, GLUT4 carbonylation, and insulin resistance in healthy men

“…The methods for label-free proteomics (GeLC-MS/MS) analysis were as previously described (42), except that the nanoelectrospray ionization (ESI) tandem MS was performed with a Q Exactive Orbitrap mass spectrometer (Thermo Scientific). ESI was delivered with a stainless steel emitter (30-µM inside diameter, 40-mm length, Thermo Scientific) at a spray voltage of −1800 V. MS/MS fragmentation was performed on the five most abundant ions on each spectrum using collision-induced dissociation with dynamic exclusion (excluded for 10.0 s after one spectrum), with automatic switching between MS and MS/MS modes.…”

A Splice Variant of the Human Ion Channel TRPM2 Modulates Neuroblastoma Tumor Growth through Hypoxia-inducible Factor (HIF)-1/2α

“…Extracted proteins in radioimmune precipitation assay buffer from pooled xenograft tumors stably transfected with TRPM2-L (n ϭ 5) or TRPM2-S (n ϭ 5) and harvested at 6 weeks after cell injection were processed for GeLC-MS/MS analysis as described previously (50). Briefly, electrospray ionization tandem MS was performed using a Bruker HCT Ultra ion trap mass spectrometer.…”