Rare case of papillary fibroelastoma resection with concomitant cox-maze IV procedure.

Primary cardiac tumors represent 0.1% of all cardiac tumors, making them a rare pathologic phenomenon. The second most common cardiac tumors are papillary fibroelastomas, which also represent the most common valvular tumors. This report examines a rare case of a patient that underwent resection of papillary fibroelastoma with simultaneous Cox-Maze IV procedure for treatment of atrial fibrillation. This 67-year-old male patient was initially scheduled for transcatheter ablation for treatment of rate-controlled atrial fibrillation. During a pre-procedural trans-thoracic echocardiogram, it was discovered that the patient had a moderately sized pedunculated mass on the aortic valve, suspicious of papillary fibroelastoma. Despite the patient having no history of embolic events or aortic insufficiency from the papillary fibroelastoma, the transcatheter ablation procedure was canceled. He was referred to cardiothoracic surgery for further evaluation, and it was determined that this patient was a candidate for papillary fibroelastoma resection along with Cox-Maze IV procedure for atrial fibrillation.

Function of the MYND Domain and C-Terminal Region in Regulating the Subcellular Localization and Catalytic Activity of the SMYD Family Lysine Methyltransferase Set5.

SMYD lysine methyltransferases target histones and nonhistone proteins for methylation and are critical regulators of muscle development and implicated in neoplastic transformation. They are characterized by a split catalytic SET domain and an intervening MYND zinc finger domain, as well as an extended C-terminal domain. Saccharomyces cerevisiae contains two SMYD proteins, Set5 and Set6, which share structural elements with the mammalian SMYD enzymes. Set5 is a histone H4 lysine 5, 8, and 12 methyltransferase, implicated in the regulation of stress responses and genome stability. While the SMYD proteins have diverse roles in cells, there are many gaps in our understanding of how these enzymes are regulated. Here, we performed mutational analysis of Set5, combined with phosphoproteomics, to identify regulatory mechanisms for its enzymatic activity and subcellular localization. Our results indicate that the MYND domain promotes Set5 chromatin association in cells and is required for its role in repressing subtelomeric genes. Phosphoproteomics revealed extensive phosphorylation of Set5, and phosphomimetic mutations enhance Set5 catalytic activity but diminish its ability to interact with chromatin in cells. These studies uncover multiple regions within Set5 that regulate its localization and activity and highlight potential avenues for understanding mechanisms controlling the diverse roles of SMYD enzymes.