Rabbit Anti-Human EEF1a1 Polyclonal Antibody Knockout Validated

The formation of a pH gradient, which is characterized by intracellular alkalinization and extracellular acidification, plays a key role in the growth and metastasis of tumor cells. However, the underlying mechanisms of alkalinization-induced cell growth are not known. In this study, we investigated the roles of eukaryotic translation elongation factor 1 a (eEF1A) in alkalinization-induced cell growth. In all cell lines tested (NIH3T3, HEK293, and HeLa), cell growth was affected by the modulation of intracellular pH. In general, weak intracellular alkalinization produced increased cell growth, whereas intracellular acidification resulted in decreased cell growth. It is interesting to note that portions of actin-bound eEF1A proteins were gradually reduced from acidic to alkaline conditions, suggesting an increase in levels of functionally active, free-form eEF1A. Over-expression of eEF1A caused increased cell growth in HeLa cells. It should be noted that dissociation of eEF1A from actin by transfection with the actin-binding domain deleted eEF1A construct further increased cell growth under acidic conditions, whereas most of the intact eEF1A was bound to actin. Conversely, knockdown of eEF1A by treatment with eEF1A1 and eEF1A2 siRNAs nullified the effects of alkalinization-induced cell growth. The above findings suggest that an increase in free-form eEF1A under alkaline conditions plays a critical role in alkalinization-induced cell growth. Laboratory Investigation (2009) 89, 867-874; doi:10.1038/labinvest.2009.53; published online 8 June 2009

The intracellular pathogen Mycobacterium tuberculosis (Mtb) can survive in the host and cause disease by interfering with a variety of cellular functions. The mammalian cell entry 2 (mce2) operon of Mtb has been shown to contribute to tuberculosis pathogenicity. However, little is known about the regulatory roles of Mtb Mce2 family proteins towards host cellular functions. Here we show that the Mce2 family protein Mce2E suppressed the macrophage innate immune response and promoted epithelial cell proliferation. Mce2E inhibited activation of the extracellular signal-regulated kinase (ERK) and Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) signaling pathways in a non-canonical D motif (a MAPK-docking motif)-dependent manner, leading to reduced expression of TNF and IL-6 in macrophages. Furthermore, Mce2E promoted proliferation of human lung epithelium-derived lung adenoma A549 cells by inhibiting K48-linked polyubiquitination of eEF1A1 in a beta strand region-dependent manner. In summary, Mce2E is a novel multifunctional Mtb virulence factor that regulates host cellular functions in a niche-dependent manner. Our data suggest a potential novel target for TB therapy.