Yeast WHI2 was originally identified in a genetic screen for regulators of cell cycle arrest and later suggested to function in general stress responses. However, the function of Whi2 is unknown. Whi2 has predicted structure and sequence similarity to human KCTD family proteins, which have been implicated in several cancers and are causally associated with neurological disorders but are largely uncharacterized. The identification of conserved functions between these yeast and human proteins may provide insight into disease mechanisms. We report that yeast WHI2 is a new negative regulator of TORC1 required to suppress TORC1 activity and cell growth specifically in response to low amino acids. In contrast to current opinion, WHI2 is dispensable for TORC1 inhibition in low glucose. The only widely conserved mechanism that actively suppresses both yeast and mammalian TORC1 specifically in response to low amino acids is the conserved SEACIT/GATOR1 complex that inactivates the TORC1-activating RAG-like GTPases. Unexpectedly, Whi2 acts independently and simultaneously with these established GATOR1-like Npr2-Npr3-Iml1 and RAG-like Gtr1-Gtr2 complexes, and also acts independently of the PKA pathway. Instead, Whi2 inhibits TORC1 activity through its binding partners, protein phosphatases Psr1 and Psr2, which were previously thought to only regulate amino acid levels downstream of TORC1. Furthermore, the ability to suppress TORC1 is conserved in the SKP1/BTB/POZ domain-containing, Whi2-like human protein KCTD11 but not other KCTD family members tested.

The discovery of the green fluorescent protein from Aequorea victoria has revolutionized the field of cell and molecular biology. Since its discovery a growing panel of fluorescent proteins, fluorophores and fluorescent-coupled staining methodologies, have expanded the analytical capabilities of flow cytometry. Here, we exploit the power of genetic engineering to barcode individual cells with genes encoding fluorescent proteins. For genetic engineering, we utilize retroviral technology, which allows for the expression of ectopic genetic information in a stable manner in mammalian cells. We have genetically barcoded both adherent and nonadherent cells with different fluorescent proteins. Multiplexing power was increased by combining both the number of distinct fluorescent proteins, and the fluorescence intensity in each channel. Moreover, retroviral expression has proven to be stable for at least a 6-month period, which is critical for applications such as biological screens. We have shown the applicability of fluorescent barcoded multiplexing to cell-based assays that rely themselves on genetic barcoding, or on classical staining protocols. Fluorescent genetic barcoding gives the cell an inherited characteristic that distinguishes it from its counterpart. Once cell lines are developed, no further manipulation or staining is required, decreasing time, nonspecific background associated with staining protocols, and cost. The increasing number of discovered and/or engineered fluorescent proteins with unique absorbance/ emission spectra, combined with the growing number of detection devices and lasers, increases multiplexing versatility, making fluorescent genetic barcoding a powerful tool for flow cytometry-based analysis. V C 2013 International Society for Advancement of Cytometry

Fungal pathogens pose an increasing threat to public health. Limited clinical drug regimens and emerging drug-resistant isolates challenge infection control. The global burden of human fungal pathogens is estimated at 1 billion infections and 1.5 million deaths annually. In addition, plant fungal pathogens increasingly threaten global food resources. Novel strategies are needed to combat emerging fungal diseases and pan-resistant fungi. An untapped mechanistically novel approach is to pharmacologically activate the intrinsic cell death pathways encoded by pathogenic fungi. This strategy is analogous to new anti-cancer therapeutics now entering the clinic. Here we summarize the best understood examples of cell death mechanisms encoded by pathogenic fungi, contrast these to mammalian cell death pathways, and highlight the gaps in knowledge towards identifying potential death effectors as druggable targets.