EDC3 phosphorylation regulates growth and invasion through controlling P‐body formation and dynamics

Regulation of mRNA stability and translation plays a critical role in determining protein abundance within cells. Processing bodies (P‐bodies) are critical regulators of these processes. Here, we report that the Pim1 and 3 protein kinases bind to the P‐body protein enhancer of mRNA decapping 3 (EDC3) and phosphorylate EDC3 on serine (S)161, thereby modifying P‐body assembly. EDC3 phosphorylation is highly elevated in many tumor types, is reduced upon treatment of cells with kinase inhibitors, and blocks the localization of EDC3 to P‐bodies. Prostate cancer cells harboring an EDC3 S161A mutation show markedly decreased growth, migration, and invasion in tissue culture and in xenograft models. Consistent with these phenotypic changes, the expression of integrin β1 and α6 mRNA and protein is reduced in these mutated cells. These results demonstrate that EDC3 phosphorylation regulates multiple cancer‐relevant functions and suggest that modulation of P‐body activity may represent a new paradigm for cancer treatment.     

Analysis of leukotriene B4 in human lung lavage by HPLC and mass spectrometry

Although leukotrienes are beleived to mediate symptoms of human lung disease, there is little direct evidence of their existence in the lung. This is due to the difficulty in obtaining lung samples, the small amounts of leukotrienes typically present in such samples and the problems associated with purifying and analyzing leukotrienes in complex biological samples. In this study, lung lavagates were collected and analyzed for leukotrienes. The methods in this analysis included solid phase extraction using a C-18 reverse phase cartridge followed by HPLC using a new photodiode array detector which provides full UV spectra of eluting compounds. Lung lavage fluid from a patient with chronic pulmonary disease contained a compound with a UV spectra of LTB₄ which was found to elute with synthetic [³H]-LTB₄. This compound was confirmed as PTB using gas chromarography/mass spectrometry in the negative ion-chemical ionization mode. The inclusion of oxygen-18 LTB₄ as an internal standard allowed approximate quantitation of the amount of LTB₄ present in this 5 ml lung lavagate as 40–50 ng.     

Centrosomal ALIX regulates mitotic spindle orientation by modulating astral microtubule dynamics

The orientation of the mitotic spindle (MS) is tightly regulated, but the molecular mechanisms are incompletely understood. Here we report a novel role for the multifunctional adaptor protein ALG‐2‐interacting protein X (ALIX) in regulating MS orientation in addition to its well‐established role in cytokinesis. We show that ALIX is recruited to the pericentriolar material (PCM) of the centrosomes and promotes correct orientation of the MS in asymmetrically dividing Drosophila stem cells and epithelial cells, and symmetrically dividing Drosophila and human epithelial cells. ALIX‐deprived cells display defective formation of astral microtubules (MTs), which results in abnormal MS orientation. Specifically, ALIX is recruited to the PCM via Drosophila Spindle defective 2 (DSpd‐2)/Cep192, where ALIX promotes accumulation of γ‐tubulin and thus facilitates efficient nucleation of astral MTs. In addition, ALIX promotes MT stability by recruiting microtubule‐associated protein 1S (MAP1S), which stabilizes newly formed MTs. Altogether, our results demonstrate a novel evolutionarily conserved role of ALIX in providing robustness to the orientation of the MS by promoting astral MT formation during asymmetric and symmetric cell division.