The adaptor-related protein complex 2, alpha 2 subunit (AP2α2) gene is a peroxisome proliferator-activated receptor cardiac target gene

Possible key microRNAs and corresponding molecular mechanisms for atrial fibrillation

Objective:

We aimed to find crucial microRNAs (miRNAs) associated with the development of atrial fibrillation (AF), and then try to elucidate the possible molecular mechanisms of miRNAs in AF.

Methods:

The miRNA microarray, GSE68475, which included 10 right atrial appendage samples from patients with persistent AF and 11 samples from patients with normal sinus rhythm, was used for the analysis. After data preprocessing, differentially expressed miRNAs were screened using limma. Target genes of miRNAs were predicted using miRWalk2.0. We then conducted functional enrichment analyses for miRNA and target genes. Protein-protein interaction (PPI) network and module analyses for target genes were performed. Finally, transcription factors (TFs)-target genes regulatory network was predicted and constructed.

Results:

Seven genes, including CAMK2D, IGF2R, PPP2R2A, PAX6, POU3F2, YWHAE, and AP2A2, were targeted by TFs. Among these seven genes, CAMK2D (targeted by miR-31-5p), IGF2R (targeted by miR-204-5p), PAX6 (targeted by miR-223-3p), POU3F2 (targeted by miR-204-5p), YWHAE (targeted by miR-31-5p), and AP2A2 (targeted by miR-204-5p) belonged to the top 10 degree genes in the PPI network. Notably, MiR-204-5p, miR-31-5p, and miR-223-3p had more target genes. Besides, CAMK2D was enriched in some pathways, such as adrenergic signaling in cardiomyocytes pathway and cAMP signaling pathway. YWHAE was enriched in the Hippo signaling pathway.

Conclusion:

miR-31-5p played a crucial role in cardiomyocytes by targeting CAMK2D and YWHAE via cAMP and Hippo signaling pathways. miR-204 was involved in the progression of AF by regulating its target genes IGF2R, POU3F2, and AP2A2. On the other hand, miR-223-3p functioned in AF by targeting PAX6, which was associated with the regulation of apoptosis in AF. This study would provide a theoretical basis and potential therapeutic targets for the treatment of AF.

The role of Ap2a2 in PPARα-mediated regulation of lipolysis in adipose tissue

Adipose tissue plays a major role in the regulation of systemic metabolic homeostasis, with the AP2 adaptor complex being important in clathrin-mediated endocytosis (CME) of various cell surface receptors, including glucose transporter 4, the insulin receptor, and β-adrenergic receptors (ARs). One of the AP2 subunits, adaptor-related protein complex 2, α2 subunit (Ap2a2), has recently been identified as a peroxisome proliferator-activated receptor (PPAR)α target gene. The effects of PPARα on the AP2 adaptor complex and CME are unknown. We generated adipocyte-specific Ap2a2 knockout mice and investigated their metabolism when fed a standard chow or high-fat diet, without and with supplementation with the PPARα-agonist WY-14643 (WY). Although Ap2a2 deletion had only minor effects on glycaemic control, it led to substantial impairment in β-adrenergic activation of lipolysis, as evidenced by a loss of cAMP response, PKA activation, and glycerol/fatty acid release. These differences were related to increased cell surface localization of the β2- and β3-ARs. Lipolytic defects were accompanied by impaired WY-mediated loss of fat mass and whole-body fat oxidation. This study demonstrates a novel role for PPARα in β-adrenergic regulation of adipose tissue lipolysis and for adipose tissue in supplying adequate substrate to other peripheral tissues to accommodate the increase in systemic fatty acid oxidation that occurs upon treatment with PPARα agonists.-Montgomery, M. K., Bayliss, J., Keenan, S., Rhost, S., Ting, S. B., Watt, M. J. The role of Ap2a2 in PPARα-mediated regulation of lipolysis in adipose tissue.

A genetic variant near adaptor-related protein complex 2 alpha 2 subunit gene is associated with coronary artery disease in a Chinese population

Background

Adaptor-related protein complex 2 alpha 2 subunit (AP2A2) gene encodes a protein-a subunit of the AP-2 adaptor protein complex. Evidence has revealed that benzodiazepine receptor-associated protein 1 (BZRAP1) is abundant in the hippocampus with potential effects on brain diseases. Recently, an epidemiological study reported that two variants (rs7396366 and rs2526378) closest to the AP2A2 and BZRAP1 genes are associated with higher plasma lipids and Alzheimer’s disease. Whether the two single nucleotide polymorphisms (SNPs) are actually relevant to coronary artery disease (CAD) and CAD severity remains elusive. Our aim was to assess whether these two SNPs are relevant to CAD and its severity in a Chinese population.

Methods

Three hundred and thirty-five patients with documented CAD (282 stable CAD, 28 non-ST-segment elevation myocardial infarction, 25 ST-segment elevation myocardial infarction), and 372 non-CAD controls were included in the study. The participants were divided into two groups according to coronary angiography results. CAD patients were further demarcated into subgroups with one-, two-, or three-vessel stenosis. Genotypes at rs7396366 and rs2526378 were examined using polymerase chain reaction-ligase detection reaction. The association between these two SNPs with CAD and its severity were analyzed.

Results

The frequency of the rs7396366 TT genotype was significantly higher in CAD patients than in controls (13.7% vs. 7.8%, 95% CI: 1.15–3.07, P = 0.014). Subjects with a variant genotype T allele had an increased risk of CAD compared with G allele carriers (additive model: 95% CI: 1.21–3.35, P = 0.008). After adjustment for traditional cardiovascular risk factors, analysis of the dominant models involving rs7396366 also showed that T allele carriers had a significantly higher risk for CAD than G allele carriers had (dominant model: OR 1.48, 95% CI: 1.03–2.14, P = 0.035). Age, sex, type 2 diabetes mellitus, fasting plasma glucose, and the TT genotype in rs7396366 were significantly associated with three-vessel lesions. Despite these significant outcomes of rs7396366, information on rs2526378 showed no significant difference between CAD patients and non-CAD controls.

Conclusion

Our results show that the T allele and TT genotype in rs7396366, closest to the AP2A2 gene, are linked to an increased risk of CAD and its severity in a Chinese population.

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0905-2) contains supplementary material, which is available to authorized users.

Ubiquitin Ligases and Posttranslational Regulation of Energy in the Heart: The Hand that Feeds

Heart failure (HF) is a costly and deadly syndrome characterized by the reduced capacity of the heart to adequately provide systemic blood flow. Mounting evidence implicates pathological changes in cardiac energy metabolism as a contributing factor in the development of HF. While the main source of fuel in the healthy heart is the oxidation of fatty acids, in the failing heart the less energy efficient glucose and glycogen metabolism are upregulated. The ubiquitin proteasome system plays a key role in regulating metabolism via protein-degradation/regulation of autophagy and regulating metabolism-related transcription and cell signaling processes. In this review, we discuss recent research that describes the role of the ubiquitin-proteasome system (UPS) in regulating metabolism in the context of HF. We focus on ubiquitin ligases (E3s), the component of the UPS that confers substrate specificity, and detail the current understanding of how these E3s contribute to cardiac pathology and metabolism. © 2017 American Physiological Society. Compr Physiol 7:841-862, 2017.

VEGFA rSNPs, transcriptional factor binding sites and human disease

Three regulatory SNPs (rSNPs) in the promoter region of the vascular endothelial growth factor-A (VEGFA) gene have been significantly associated with several human diseases or conditions. The rSNP alleles alter the DNA landscape for potential transcriptional factors to attach, resulting in changes in transcriptional factor binding sites (TFBS). These TFBS changes are examined with respect to the human diseases which have been found to be significantly associated with the rSNPs.