Carbon dots as a luminescence sensor for ultrasensitive detection of phosphate and their bioimaging properties

Highly blue fluorescence carbon dots were synthesized by one‐step hydrothermal treatment of potatoes. The as‐obtained C‐dots have been applied to bioimaging of HeLa cells, which shows their excellent biocompatibility and low cytotoxicity. The results reveal that C‐dots are promising for real cell imaging applications. In addition, the carbon dots can be utilized as a probe for sensing phosphate. Copyright © 2014 John Wiley & Sons, Ltd.     

Elevated glucose-6-phosphate dehydrogenase expression in the cervical cancer cases is associated with the cancerigenic event of high-risk human papillomaviruses

The most important etiologic agent in the pathogenesis of cervical cancers (CCs) is human papillomavirus (HPV), while the mechanisms underlying are still not well known. Glucose-6-phosphate dehydrogenase (G6PD) is reported to elevate in various tumor cells. However, no available references elucidated the correlation between the levels of G6PD and HPV-infected CC until now. In the present study, we explored the possible role of G6PD in the pathology of CC induced by HPV infection. Totally 48 patients with HPV + CC and another 63 healthy women enrolled in the clinical were employed in the present study. Overall, prevalence of cervical infection with high-risk-HPV (HR-HPV) type examined was HPV-16, followed by HPV-18. The expressions of G6PD in CC samples were also detected by immunohistochemistry (IHC), qRT-PCR, and Western blot. Regression analysis showed elevated G6PD level was positively correlated with the CC development in 30–40 aged patients with HR-HPV-16/18 infection. The HPV16 + Siha, HPV18 + Hela, and HPV-C33A cell lines were employed and transfected with G6PD deficient vectors developed in vitro. MTT and flow cytometry were also employed to determine the survival and apoptosis of CC cells after G6PD expressional inhibition. Our data revealed that G6PD down-regulation induced poor proliferation and more apoptosis of HPV18 + Hela cells, when compared with that of HPV16 + Siha and HPV-C33A cells. These findings suggest that G6PD expressions in the HR-HPV + human CC tissues and cell lines play an important role in tumor growth and proliferation.     

Drosophila S6 Kinase Like Inhibits Neuromuscular Junction Growth by Downregulating the BMP Receptor Thickveins

Synaptic connections must be precisely controlled to ensure proper neural circuit formation. In Drosophila melanogaster, bone morphogenetic protein (BMP) promotes growth of the neuromuscular junction (NMJ) by binding and activating the BMP ligand receptors wishful thinking (Wit) and thickveins (Tkv) expressed in motor neurons. We report here that an evolutionally conserved, previously uncharacterized member of the S6 kinase (S6K) family S6K like (S6KL) acts as a negative regulator of BMP signaling. S6KL null mutants were viable and fertile but exhibited more satellite boutons, fewer and larger synaptic vesicles, larger spontaneous miniature excitatory junctional potential (mEJP) amplitudes, and reduced synaptic endocytosis at the NMJ terminals. Reducing the gene dose by half of tkv in S6KL mutant background reversed the NMJ overgrowth phenotype. The NMJ phenotypes of S6KL mutants were accompanied by an elevated level of Tkv protein and phosphorylated Mad, an effector of the BMP signaling pathway, in the nervous system. In addition, Tkv physically interacted with S6KL in cultured S2 cells. Furthermore, knockdown of S6KL enhanced Tkv expression, while S6KL overexpression downregulated Tkv in cultured S2 cells. This latter effect was blocked by the proteasome inhibitor MG132. Our results together demonstrate for the first time that S6KL regulates synaptic development and function by facilitating proteasomal degradation of the BMP receptor Tkv.     

Epigenetic regulation of autophagy by the methyltransferase EZH2 through an MTOR-dependent pathway

Macroautophagy is an evolutionarily conserved cellular process involved in the clearance of proteins and organelles. Although the autophagy regulation machinery has been widely studied, the key epigenetic control of autophagy process still remains unknown. Here we report that the methyltransferase EZH2 (enhancer of zeste 2 polycomb repressive complex 2 subunit) epigenetically represses several negative regulators of the MTOR (mechanistic target of rapamycin [serine/threonine kinase]) pathway, such as TSC2, RHOA, DEPTOR, FKBP11, RGS16 and GPI. EZH2 was recruited to these genes promoters via MTA2 (metastasis associated 1 family, member 2), a component of the nucleosome remodeling and histone deacetylase (NuRD) complex. MTA2 was identified as a new chromatin binding protein whose association with chromatin facilitated the subsequent recruitment of EZH2 to silenced targeted genes, especially TSC2. Downregulation of TSC2 (tuberous sclerosis 2) by EZH2 elicited MTOR activation, which in turn modulated subsequent MTOR pathway-related events, including inhibition of autophagy. In human colorectal carcinoma (CRC) tissues, the expression of MTA2 and EZH2 correlated negatively with expression of TSC2, which reveals a novel link among epigenetic regulation, the MTOR pathway, autophagy induction, and tumorigenesis.     

Modification of BECN1 by ISG15 plays a crucial role in autophagy regulation by type I IFN/interferon

ISG15 (ISG15 ubiquitin-like modifier), a ubiquitin-like protein, is one of the major type I IFN (interferon) effector systems. ISG15 can be conjugated to target proteins (ISGylation) via the stepwise action of E1, E2, and E3 enzymes. Conjugated ISG15 can be removed (deISGylated) from target proteins by USP18 (ubiquitin-specific peptidase 18). Here we investigated the role of deISGylation by USP18 in regulating autophagy and EGFR degradation in cells treated with type I IFNs. We show that type I IFN induced expression of ISG15 leads to ISGylation of BECN1 at Lys117, as well as Lys263, Lys265, and Lys266 which competes with Lys63 ubiquitination of BECN1. We demonstrate that ISGylation of BECN1 at Lys117, as well as Lys263, Lys265, and Lys266 serve an important role in negative regulation of intracellular processes including autophagy and EGFR degradation that are critically dependent upon the activity of class III PtdIns 3-kinase. Our studies provide fundamental new mechanistic insights into the innate immunity response implemented by type I IFNs.