MoMaf1 Mediates Vegetative Growth, Conidiogenesis, and Pathogenicity in the Rice Blast Fungus Magnaporthe oryzae.

In eukaryotes, Maf1 is an essential and specific negative regulator of RNA polymerase (Pol) III. Pol III, which synthesizes 5S RNA and transfer RNAs (tRNAs), is suppressed by Maf1 under the conditions of nutrient starvation or environmental stress. Here, we identified M. oryzae MoMaf1, a homolog of ScMaf1 in budding yeast. A heterogeneous complementation assay revealed that MoMaf1 restored growth defects in the ΔScmaf1 mutant under SDS stress. Destruction of MoMAF1 elevated 5S rRNA content and increased sensitivity to cell wall agents. Moreover, the ΔMomaf1 mutant exhibited reduced vegetative growth, conidiogenesis, and pathogenicity. Interestingly, we found that MoMaf1 underwent nuclear-cytoplasmic shuffling, through which MoMaf1 accumulated in nuclei under nutrient deficiency or upon the interaction of M. oryzae with rice. Therefore, this study can help to elucidate the pathogenic molecular mechanism of M. oryzae.

Evaluation of hypocrellin A-loaded lipase sensitive polymer micelles for intervening methicillin-resistant Staphylococcus Aureus antibiotic-resistant bacterial infection.

There is an urgent need for new antibacterial strategies to overcome the emergence of antibiotic resistance. Antibacterial photodynamic therapy (APDT) may be an effective method to deliver photosensitizers for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. Here, we report that the photosensitizer hypocrellin A (HA) loaded into lipase-sensitive methoxy poly (ethylene glycol)-block-poly(ε-caprolactone) (mPEG-PCL) micelles showed high anti-MRSA activity in vitro and in vivo by PDT. Once the micelles come into contact with bacteria that secrete lipase, the PCL is degraded to release HA. Our results showed that the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of mPEG-PCL/HA micelles after light irradiation were 0.69 and 1.38 mg/L (HA concentration), respectively. In the dark, the MIC and MBC of the micelles were 250 and 500 mg/L (HA concentration), respectively. The fluorescent stain results further demonstrated the photodynamic antibacterial activity of mPEG-PCL/HA micelles. The survival rate of mice subjected to experimental acute peritonitis increased to 86% after treated with the micelles. The polymeric micelles showed low hemolytic activity and biocompatibility, simultaneously preventing aggregation in vivo and enhancing the water solubility of HA. Thus, the photosensitizer HA loaded micelles could be used as APDT for infections caused by bacteria without antibiotic resistance.

Hypocrellin A-based photodynamic action induces apoptosis in A549 cells through ROS-mediated mitochondrial signaling pathway.

Over recent decades, many studies have reported that hypocrellin A (HA) can eliminate cancer cells with proper irradiation in several cancer cell lines. However, the precise molecular mechanism underlying its anticancer effect has not been fully defined. HA-mediated cytotoxicity and apoptosis in human lung adenocarcinoma A549 cells were evaluated after photodynamic therapy (PDT). A temporal quantitative proteomics approach by isobaric tag for relative and absolute quantitation (iTRAQ) 2D liquid chromatography with tandem mass spectrometric (LC-MS/MS) was introduced to help clarify molecular cytotoxic mechanisms and identify candidate targets of HA-induced apoptotic cell death. Specific caspase inhibitors were used to further elucidate the molecular pathway underlying apoptosis in PDT-treated A549 cells. Finally, down-stream apoptosis-related protein was evaluated. Apoptosis induced by HA was associated with cell shrinkage, externalization of cell membrane phosphatidylserine, DNA fragmentation, and mitochondrial disruption, which were preceded by increased intracellular reactive oxygen species (ROS) generations. Further studies showed that PDT treatment with 0.08 µmol/L HA resulted in mitochondrial disruption, pronounced release of cytochrome c, and activation of caspase-3, -9, and -7. Together, HA may be a possible therapeutic agent directed toward mitochondria and a promising photodynamic anticancer candidate for further evaluation.

Transferrin-Modified Nanoparticles for Photodynamic Therapy Enhance the Antitumor Efficacy of Hypocrellin A.

Photodynamic therapy (PDT) has emerged as a potent novel therapeutic modality that induces cell death through light-induced activation of photosensitizer. But some photosensitizers have characteristics of poor water-solubility and non-specific tissue distribution. These characteristics become main obstacles of PDT. In this paper, we synthesized a targeting drug delivery system (TDDS) to improve the water-solubility of photosensitizer and enhance the ability of targeted TFR positive tumor cells. TDDS is a transferrin-modified Poly(D,L-Lactide-co-glycolide (PLGA) and carboxymethyl chitosan (CMC) nanoparticle loaded with a photosensitizer hypocrellin A (HA), named TF-HA-CMC-PLGA NPs. Morphology, size distribution, Fourier transform infrared (FT-IR) spectra, encapsulation efficiency, and loading capacity of TF-HA-CMC-PLGA NPs were characterized. In vitro TF-HA-CMC-PLGA NPs presented weak dark cytotoxicity and significant photo-cytotoxicity with strong reactive oxygen species (ROS) generation and apoptotic cancer cell death. In vivo photodynamic antitumor efficacy of TF-HA-CMC-PLGA NPs was investigated with an A549 (TFR positive) tumor-bearing model in male athymic nude mice. TF-HA-CMC-PLGA NPs caused tumor delay with a remarkable tumor inhibition rate of 63% for 15 days. Extensive cell apoptosis in tumor tissue and slight side effects in normal organs were observed. The results indicated that TDDS has great potential to enhance PDT therapeutic efficacy.