Unique evolution of the UPR pathway with a novel bZIP transcription factor, Hxl1, for controlling pathogenicity of Cryptococcus neoformans.

In eukaryotic cells, the unfolded protein response (UPR) pathway plays a crucial role in cellular homeostasis of the endoplasmic reticulum (ER) during exposure to diverse environmental conditions that cause ER stress. Here we report that the human fungal pathogen Cryptococcus neoformans has evolved a unique UPR pathway composed of an evolutionarily conserved Ire1 protein kinase and a novel bZIP transcription factor encoded by HXL1 (HAC1 and XBP1-Like gene 1). C. neoformans HXL1 encodes a protein lacking sequence homology to any known fungal or mammalian Hac1/Xbp1 protein yet undergoes the UPR-induced unconventional splicing in an Ire1-dependent manner upon exposure to various stresses. The structural organization of HXL1 and its unconventional splicing is widely conserved in C. neoformans strains of divergent serotypes. Notably, both C. neoformans ire1 and hxl1 mutants exhibited extreme growth defects at 37°C and hypersensitivity to ER stress and cell wall destabilization. All of the growth defects of the ire1 mutant were suppressed by the spliced active form of Hxl1, supporting that HXL1 mRNA is a downstream target of Ire1. Interestingly, however, the ire1 and hxl1 mutants showed differences in thermosensitivity, expression patterns for a subset of genes, and capsule synthesis, indicating that Ire1 has both Hxl1-dependent and -independent functions in C. neoformans. Finally, Ire1 and Hxl1 were shown to be critical for virulence of C. neoformans, suggesting UPR signaling as a novel antifungal therapeutic target

Integrated 18F-FDG PET/MRI in breast cancer: Early prediction of response to neoadjuvant chemotherapy

Purpose To explore whether integrated F-18-FDG PET/MRI can be used to predict pathological response to neoadjuvant chemotherapy (NAC) in patients with breast cancer. Methods Between November 2014 and April 2016, 26 patients with breast cancer who had received NAC and subsequent surgery were prospectively enrolled. Each patient underwent F-18-FDG PET/MRI examination before and after the first cycle of NAC. Qualitative MRI parameters, including morphological descriptors and the presence of peritumoral oedema were assessed. Quantitatively, PET parameters, including maximum standardized uptake value, metabolic tumour volume and total lesion glycolysis (TLG), and MRI parameters, including washout proportion and signal enhancement ratio (SER), were measured. The performance of the imaging parameters singly and in combination in predicting a pathological incomplete response (non-pCR) was assessed. Results Of the 26 patients, 7 (26.9%) exhibited a pathological complete response (pCR), and 19 (73.1%) exhibited a non-pCR. No significant differences were found between the pCR and non-pCR groups in the qualitative MRI parameters. The mean percentage reductions in TLG(30%) on PET and SER on MRI were significantly greater in the pCR group than in the non-pCR group (TLG30% -64.8 +/- 15.5% vs. -25.4 +/- 48.7%, P = 0.005; SER -34.6 +/- 19.7% vs. -8.7 +/- 29.0%, P = 0.040). The area under the receiver operating characteristic curve for the percentage change in TLG30% (0.789, 95% CI 0.614 to 0.965) was similar to that for the percentage change in SER (0.789, 95% CI 0.552 to 1.000; P = 1.000). The specificity of TLG30% in predicting pCR) was 100% (7/7) and that of SER was 71.4% (5/7). The sensitivity of TLG30% in predicting non-pCR was 63.2% (12/19) and that of SER was 84.2% (16/19). When the combined TLG30% and SER criterion was applied, sensitivity was 100% (19/19), and specificity was 71.4% (5/7). Conclusion F-18-FDG PET/MRI can be used to predict non-pCR after the first cycle of NAC in patients with breast cancer and has the potential to improve sensitivity by the addition of MRI parameters to the PET parameters