Analysis of gene expression profiles in HeLa cells in response to overexpression or siRNA-mediated depletion of NASP

<p>Abstract</p> <p>Background</p> <p>NASP (Nuclear Autoantigenic Sperm Protein) is a linker histone chaperone required for normal cell division. Changes in NASP expression significantly affect cell growth and development; loss of gene function results in embryonic lethality. However, the mechanism by which NASP exerts its effects in the cell cycle is not understood. To understand the pathways and networks that may involve NASP function, we evaluated gene expression in HeLa cells in which NASP was either overexpressed or depleted by siRNA.</p> <p>Methods</p> <p>Total RNA from HeLa cells overexpressing NASP or depleted of NASP by siRNA treatment was converted to cRNA with incorporation of Cy5-CTP (experimental samples), or Cy3-CTP (control samples). The labeled cRNA samples were hybridized to whole human genome microarrays (Agilent Technologies, Wilmington, Delaware, USA). Various gene expression analysis techniques were employed: Significance Analysis of Microarrays (SAM), Expression Analysis Systematic Explorer (EASE), and Ingenuity Pathways Analysis (IPA).</p> <p>Results</p> <p>From approximately 36 thousand genes present in a total human genome microarray, we identified a set of 47 up-regulated and 7 down-regulated genes as a result of NASP overexpression. Similarly we identified a set of 56 up-regulated and 71 down-regulated genes as a result of NASP siRNA treatment. Gene ontology, molecular network and canonical pathway analysis of NASP overexpression demonstrated that the most significant changes were in proteins participating in organismal injury, immune response, and cellular growth and cancer pathways (major "hubs": TNF, FOS, EGR1, NFκB, IRF7, STAT1, IL6). Depletion of NASP elicited the changed expression of proteins involved in DNA replication, repair and development, followed by reproductive system disease, and cancer and cell cycle pathways (major "hubs": E2F8, TP53, FGF, FSH, FST, hCG, NFκB, TRAF6).</p> <p>Conclusion</p> <p>This study has demonstrated that NASP belongs to a network of genes and gene functions that are critical for cell survival. We have confirmed the previously reported interactions between NASP and HSP90, HSP70, histone H1, histone H3, and TRAF6. Overexpression and depletion of NASP identified overlapping networks that included TNF as a core protein, confirming that both high and low levels of NASP are detrimental to cell cycle progression. Networks with cancer-related functions had the highest significance, however reproductive networks containing follistatin and FSH were also significantly affected, which confirmed NASP's important role in reproductive tissues. This study revealed that, despite some overlap, each response was associated with a unique gene signature and placed NASP in important cell regulatory networks.</p

Supraventricular Tachyarrhythmia and Brugada Syndrome: A Case of Atrial Fibrillation and Brugada Syndrome in a Young Patient Without Structural Heart Disease

We report a case of a 29-year old man who initially presented with a single episode of syncope. The initial electrocardiogram (ECG) showed atrial fibrillation and an ST segment elevation on lead V1. A flecainide test unmasked the Brugada syndrome. The pathophysiology of Brugada syndrome and atrial fibrillation in this patient could be connected by sodium channel dysfunction throughout the heart. In addition, we reviewed the possible connection between Brugada syndrome and atrial fibrillation. Keywords: Atrial fibrillation, Brugada Syndrome, channelopathy "Taquiarritmia Supraventricular y Síndrome de Brugada: un caso de Fibrilación Atrial y Síndrome de Brugada en un Paciente Joven sin Cardiopatía Estructural" RESUMEN Reportamos el caso de un hombre de 29 años de edad que se presentó inicialmente con un solo episodio de síncope. El electrocardiograma inicial (ECG) mostró fibrilación atrial y una elevación del segmento ST en la derivación V1. Una prueba de flecainida reveló la presencia del síndrome de Brugada. La patofisiología del síndrome de Brugada y la fibrilación atrial en este paciente podrían estar conectados por una disfunción del canal de sodio a través del corazón. Además, examinamos la posible conexión entre el síndrome de Brugada y la fibrilación atrial. Palabras claves: Fibrilación atrial, síndrome de Brugada, dysfunction del canal de sodi