Lysine residues undergo diverse and reversible post-translational modifications (PTMs). Lysine acetylation has traditionally been studied in the epigenetic regulation of nucleosomal histones that provides an important mechanism for regulating gene expression. Histone acetylation plays a key role in cardiac remodeling and function. However, recent studies have shown that thousands of proteins can be acetylated at multiple acetylation sites, suggesting the acetylome rivals the kinome as a PTM. Based on this, we examined the impact of obesity on protein lysine acetylation in the left ventricle (LV) of male c57BL/6J mice. We reported that obesity significantly increased heart enlargement and fibrosis. Moreover, immunoblot analysis demonstrated that lysine acetylation was markedly altered with obesity and that this phenomenon was cardiac tissue specific. Mass spectral analysis identified 2515 proteins, of which 65 were significantly impacted by obesity. Ingenuity Pathway Analysis® (IPA) further demonstrated that these proteins were involved in metabolic dysfunction and cardiac remodeling. In addition to total protein, 189 proteins were acetylated, 14 of which were significantly impacted by obesity. IPA identified the Cardiovascular Disease Pathway as significantly regulated by obesity. This network included aconitate hydratase 2 (ACO2), and dihydrolipoyl dehydrogenase (DLD), in which acetylation was significantly increased by obesity. These proteins are known to regulate cardiac function yet, the impact for ACO2 and DLD acetylation remains unclear. Combined, these findings suggest a critical role for cardiac acetylation in obesity-mediated remodeling; this has the potential to elucidate novel targets that regulate cardiac pathology.

Bovine mammary epithelial cells (MAC-Ts) are a common cell line for the study of mammary epithelial inflammation; these cells are used to mechanistically elucidate molecular underpinnings that contribute to bovine mastitis. Bovine mastitis is the most prevalent form of disease in dairy cattle that culminates in annual losses of two billion dollars for the US dairy industry. Thus, there is an urgent need for improved therapeutic strategies. Histone deacetylase (HDAC) inhibitors are efficacious in rodent models of inflammation, yet their role in bovine mammary cells remain unclear. HDACs have traditionally been studied in the regulation of nucleosomal DNA, in which deacetylation of histones impact chromatin accessibility and gene expression. Using MAC-T cells stimulated with tumor necrosis factor α (TNF-α) as a model for mammary cell inflammation, we report that inhibition of HDACs1 and 2 (HDAC1/2) attenuated TNF-α-mediated inflammatory gene expression. Of note, we report that HDAC1/2-mediated inflammatory gene expression was partly regulated by c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) phosphorylation. Here, we report that HDAC1/2 inhibition attenuated JNK and ERK activation and thus inflammatory gene expression. These data suggest that HDACs1 and 2 regulate inflammatory gene expression via canonical (i.e., gene expression) and noncanonical (e.g., signaling dependent) mechanisms. Whereas, further studies using primary cell lines and animal models are needed. Our combined data suggest that HDAC1/2-specific inhibitors may prove efficacious for the treatment of bovine mastitis.

Lysine residues undergo diverse and reversible post‐translational modifications that include acetylation, ubiquitylation and methylation. Lysine acetylation has traditionally been studied in the regulation of gene expression, where acetylation of histone tails alters electrostatic interactions of nucleosomal DNA. However, recent proteomic studies have identified ~4,000 proteins that can be acetylated on ~10,000 lysine residues, suggesting a more complex role for the acetylome in biological function. In the heart, treatment with histone deacetylase (HDAC) inhibitors and thus increases in lysine acetylation have been shown to be cardioprotective. Here we examined the impact of obesity on the regulation of lysine acetylation. In this study, male and female c57BL/6J mice fed a high fat diet (60% kcal from fat) had a significant increase in body weight, heart weight and left ventricle weight compared to mice fed a control diet (10% kcal from fat). Of interest, immunoblot analysis demonstrated that lysine acetylation of the left ventricle was markedly altered in both male and female mice in response to diet‐induced obesity. Moreover, these phenomena appeared to be cardiac tissue specific as no differences in lysine acetylation were observed in skeletal muscle, liver or white adipose tissue in response to obesity. As such, we recently performed isobaric tagging and mass spectral analysis to identify and quantitatively analyze changes in protein abundances as well as lysine acetylation in response to obesity. We postulate that our investigations will demonstrate, with statistical significance, the impact of obesity on regulation of the cardiac acetylome and uncover biological pathways regulated by protein acetylation potentially involved in cardiac pathology.Support or Funding InformationThe project described was supported by a grant from the National Institute of General Medical Sciences (GM103440). This work is supported by the USDA National Institute of Food and Agriculture (Hatch‐NEV00727).