Abstract 19481: ZBTB46 Regulates Endothelial Cell Cycle and Proliferation
Introduction: ZBTB46 (zDC, BTBD4) is a member of the BTB-ZF protein family of transcription factors. ZBTB46 is identified as a transcription repressor in classical dendritic cells. The role of ZBTB46 in endothelial cells (ECs) has not been studied. We have previously shown that ZBTB46 is expressed in ECs and that EC ZBTB46 expression is increased under physiologic unidirectional laminar shear stress conditions and is down-regulated by low and oscillatory shear stress patterns as seen in areas of disturbed flow. EC proliferation is important in many physiologic and pathologic processes such as angiogenesis and atherosclerosis and is affected by factors such as shear stress and growth factors.
Hypothesis: ZBTB46, which is expressed in quiescent ECs, leads to reduced EC proliferation and promotes cell cycle arrest.
Methods: We used adenoviral mediated overexpression of ZBTB46 (ZBTB46-AV, compared to control GFP-AV and no-treatment control) in three different EC lines in vitro (human umbilical vein EC, human aortic EC and human coronary artery EC) to assess its role in EC proliferation and cell cycle. siRNA down-regulation of ZBTB46 in vitro was not performed as proliferating ECs in vitro express minimal levels of ZBTB46. Gene expression levels were measured by qPCR. EC proliferation was measured by a fluorescent proliferation assay and confirmed by manual cell counting. Cell cycle was assessed by measuring DNA content by propidium iodide staining via flow cytometry.
Results: ZBTB46 mRNA expression is lower in proliferating (non-confluent) ECs compared to quiescent (confluent) ECs by 70% (n=3-6, p<0.05). Adenoviral overexpression of ZBTB46 in ECs led to increased number of cells in the G0/G1 phase of the cell cycle 48hrs post treatment by 18% (frequency of cells in various cell cycle phases: ZBTB46-AV: G0/G1: 76% - S: 11% - G2/M: 11%; GFP-AV & non-treatment control: G0/G1: 58% - S: 20% - G2/M: 20%) and reduced cell proliferation (n=3, p<0.05).
Conclusions: mRNA expression of the transcription repressor ZBTB46 is increased in confluent ECs. Increased expression of ZBTB46 in ECs leads to decreased cell proliferation and appears to promote cell cycle arrest by increasing frequency of cells in the G0/G1 phase of the cell cycle.
Author Disclosures: H. Sun: None. A. Rezvan: None.
- © 2016 by American Heart Association, Inc.