A minireview of E4BP4/NFIL3 in heart failure
JOURNAL OF CELLULAR PHYSIOLOGY
Authors: Velmurugan, Bharath Kumar; Chang, Ruey-Lin; Asokan, Shibu Marthandam; Chang, Chih-Fen; Day, Cecilia-Hsuan; Lin, Yueh-Min; Lin, Yuan-Chuan; Kuo, Wei-Wen; Huang, Chih-Yang
Abstract
Heart failure (HF) remains a major cause of morbidity and mortality worldwide. The primary cause identified for HF is impaired left ventricular myocardial function, and clinical manifestations may lead to severe conditions like pulmonary congestion, splanchnic congestion, and peripheral edema. Development of new therapeutic strategies remains the need of the hour for controlling the problem of HF worldwide. Deeper insights into the molecular mechanisms involved in etiopathology of HF indicate the significant role of calcium signaling, autocrine signaling pathways, and insulin-like growth factor-1 signaling that regulates the physiologic functions of heart growth and development such as contraction, metabolism, hypertrophy, cytokine signaling, and apoptosis. In view of these facts, a transcription factor (TF) regulating the myriad of these signaling pathways may prove as a lead candidate for development of therapeutics. Adenovirus E4 promoter-binding protein (E4BP4), also known as nuclear-factor, interleukin 3 regulated (NFIL3), a type of basic leucine zipper TF, is known to regulate the signaling processes involved in the functioning of heart. The current review discusses about the expression, structure, and functional role of E4BP4 in signaling processes with emphasis on calcium signaling mechanisms, autocrine signaling, and insulin-like growth factor II receptor-mediated processes regulated by E4BP4 that may regulate the pathogenesis of HF. We propose that E4BP4, being the critical component for the regulation of the above signaling processes, may serve as a novel therapeutic target for HF, and scientific investigations are merited in this direction.
Acute inactivation of retromer and ESCPE-1 leads to time-resolved defects in endosomal cargo sorting
JOURNAL OF CELL SCIENCE
Authors: Evans, Ashley J.; Daly, James L.; Anuar, Anis N. K.; Simonetti, Boris; Cullen, Peter J.
Abstract
Human retromer, a heterotrimer of VPS26 (VPS26A or VPS26B), VPS35 and VPS29, orchestrates the endosomal retrieval of intemalised cargo and promotes their cell surface recycling, a prototypical cargo being the glucose transporter GLUT1 (also known as SLC2A1). The role of retromer in the retrograde sorting of the cation-independent mannose 6-phosphate receptor (CI-MPR, also known as IGF2R) from endosomes back to the trans-Golgi network remains controversial. Here, by applying knocksideways technology, we develop a method for acute retromer inactivation. While retromer knocksideways in HeLa and H4 human neuroglioma cells resulted in time-resolved defects in cell surface sorting of GLUT1, we failed to observe a quantifiable defect in CI-MPR sorting. In contrast, knocksideways of the ESCPE-1 complex - a key regulator of retrograde CI-MPR sorting - revealed time-resolved defects in CI-MPR sorting. Together, these data are consistent with a comparatively limited role for retromer in ESCPE-1-mediated CI-MPR retrograde sorting, and establish a methodology for acute retromer and ESCPE-1 inactivation that will aid the time-resolved dissection of their functional roles in endosomal cargo sorting.