The drive toward more sustainable agriculture has raised the profile of crop plant nutrient-use efficiency. Here we show that a major rice nitrogen-use efficiency quantitative trait locus (qNGR9) is synonymous with the previously identified gene DEP1 (DENSE AND ERECT PANICLES 1). The different DEP1 alleles confer different nitrogen responses, and genetic diversity analysis suggests that DEP1 has been subjected to artificial selection during Oryza sativa spp. japonica rice domestication. The plants carrying the dominant dep1-1 allele exhibit nitrogen-insensitive vegetative growth coupled with increased nitrogen uptake and assimilation, resulting in improved harvest index and grain yield at moderate levels of nitrogen fertilization. The DEP1 protein interacts in vivo with both the Gα (RGA1) and Gβ (RGB1) subunits, and reduced RGA1 or enhanced RGB1 activity inhibits nitrogen responses. We conclude that the plant G protein complex regulates nitrogen signaling and modulation of heterotrimeric G protein activity provides a strategy for environmentally sustainable increases in rice grain yield.

Anaplastic lymphoma kinase (ALK) activation has been associated with many types of human cancer. Significant efforts have been devoted to the development of ALK inhibitors to antagonize the kinase activity of ALK. Four ALK inhibitors have been approved by the FDA to date for treating patients with ALK-positive non-small cell lung cancers (NSCLC). However, drug resistance has been observed in the majority of patients treated with these inhibitors. New therapeutic strategies (e.g., compounds with novel mechanisms of action) are needed to overcome the drug resistance issue. The emerging PROTAC (Proteolysis Targeting Chimera) technology has been successfully applied to selective degradation of multiple protein targets, but not ALK. Since ALK protein levels are not important for viability in mammals, ALK PROTACs could lead to novel therapeutics with minimal toxicity. Here we report the design, synthesis and biological evaluation of novel PROTACs (degraders) of ALK. MS4077 (5) and MS4078 (6) potently decreased cellular levels of oncogenic active ALK fusion proteins in a concentration- and time-dependent manner in SU-DHL-1 lymphoma and NCI-H2228 lung cancer cells. The ALK protein degradation induced by compounds 5 and 6 was cereblon and proteasome dependent. In addition, compounds 5 and 6 potently inhibited proliferation of SU-DHL-1 cells. Furthermore, compound 6 displayed good plasma exposure in a mouse pharmacokinetic study, thus is suitable for in vivo efficacy studies. We also developed MS4748 (7) and MS4740 (8), very close analogs of 5 and 6 respectively, which are incapable to degrade the ALK fusion proteins, as negative controls. Compounds 5-8 are valuable chemical tools for investigating effects of ALK pharmacological degradation. Our study paved the way for developing the next generation of ALK PROTACs.

SignificancePulmonary alveolar type I (AT1) cells are essential for the gas-exchange function of lungs. AT1 cells retain their cellular plasticity during injury-induced alveolar regeneration. However, we know very little about the developmental heterogeneity of the AT1 cell population. Our study identified a robust genetic marker of postnatal AT1 cells, insulin-like growth factor-binding protein 2 (Igfbp2). We use this marker to demonstrate that the postnatal AT1 cell population actually consists of two AT1 cell subtypes (Hopx+Igfbp2+ and Hopx+Igfbp2− AT1 cells) with distinct cell fates during alveolar regeneration. The large majority of adult AT1 cells expresses Igfbp2 and cannot transdifferentiate into AT2 cells during post pneumonectomy formation of new alveoli. Therefore, Hopx+Igfbp2+ AT1 cells represent the terminally differentiated population of AT1 cells.