Tissue regeneration is a medical challenge faced in injury from disease and during medical treatments such as bone marrow transplantation. Prostaglandin PGE2, which supports expansion of several types of tissue stem cells, is a candidate therapeutic target for promoting tissue regeneration in vivo. Here we show that inhibition of 15-hydroxyprostaglandin dehydrogenase (15-PGDH), a prostaglandin-degrading enzyme, potentiates tissue regeneration in multiple organs in mice. In a chemical screen, we identify a small-molecule inhibitor of 15-PGDH (SW033291) that increases prostaglandin PGE2 levels in bone marrow and other tissues. SW033291 accelerates hematopoietic recovery in mice receiving a bone marrow transplant. SW033291 also promotes tissue regeneration in mouse models of colon and liver injury. Tissues from 15-PGDH knockout mice demonstrate similar increased regenerative capacity. These findings raise the possibility that inhibiting 15-PGDH could be a useful therapeutic strategy in several distinct clinical settings.

Following its tyrosine phosphorylation, STAT3 is methylated on K140 by the histone methyl transferase SET9 and demethylated by LSD1 when it is bound to a subset of the promoters that it activates. Methylation of K140 is a negative regulatory event, because its blockade greatly increases the steady-state amount of activated STAT3 and the expression of many (i.e., SOCS3) but not all (i.e., CD14) STAT3 target genes. Biological relevance is shown by the observation that overexpression of SOCS3 when K140 cannot be methylated blocks the ability of cells to activate STAT3 in response to IL-6. K140 methylation does not occur with mutants of STAT3 that do not enter nuclei or bind to DNA. Following treatment with IL-6, events at the SOCS3 promoter occur in an ordered sequence, as shown by chromatin immunoprecipitations. Y705-phosphoryl-STAT3 binds first and S727 is then phosphorylated, followed by the coincident binding of SET9 and dimethylation of K140, and lastly by the binding of LSD1. We conclude that the lysine methylation of promoter-bound STAT3 leads to biologically important down-regulation of the dependent responses and that SET9, which is known to help provide an activating methylation mark to H3K4, is recruited to the newly activated SOCS3 promoter by STAT3. (2) and some of the same lysine side chains can be either methylated or acetylated. These modifications alter chromatin structure, often by providing entry sites for proteins that determine higher-order chromatin organization, leading to the activation or inactivation of specific genes. In addition, methylation and demethylation of p53 and NFκB are carried out by enzymes previously known to modify only histones. For p53, the reactions occur on K370, K372, and K382 (3). For NFκB, K37 is methylated by SET9 (4), and K218 and K221 are methylated by NSD1 and demethylated by FBXL11 (5).STAT3 is phosphorylated on tyrosine and serine residues in response to many different cytokines and growth factors, leading to the formation of dimers through reciprocal phosphotyrosine-SH2 interactions (6). Activated STAT3 dimers bind to and activate the promoters of target genes. In addition to phosphorylation, STAT3 was reported to be acetylated at K685 following cytokine stimulation, and the K685R mutation blocked its activation (7), but these observations have been disputed (8). Ray et al. (9) reported that K49 and K87 of STAT3 are acetylated by p300 and that the K-R mutations resulted in a STAT3 protein that is able to translocate into nuclei, but unable to bind to p300. Here, we show that, in response to IL-6, STAT3 is methylated on K140 by the H3K4 methyl transferase SET9 and demethylated by the H3K4 demethylase LSD1 (lysine-specific demethylase 1, also named BHC110). Prevention of methylation by mutation of K140 greatly enhances the induction of one group of genes in response to IL-6, but has little effect on a second group, and inhibits the activation of a third group. Several lines of evidence indicate that methylation takes place as STAT3 is bound to promoters in the f...

The ubiquitous inducible transcription factor NF-κB plays central roles in immune and inflammatory responses and in tumorigenesis. Complex posttranslational modifications of the p65 subunit (RelA) are a major aspect of the extremely flexible regulation of NF-κB activity. Although phosphorylation, acetylation, ubiquitination, and lysine methylation of NF-κB have been well described, arginine methylation has not yet been found. We now report that, in response to IL-1β, the p65 subunit of NF-κB is dimethylated on arginine 30 (R30) by protein-arginine methyltransferase 5 (PRMT5). Expression of the R30A and R30K mutants of p65 substantially decreased the ability of NF-κB to bind to κB elements and to drive gene expression. A model in which dimethyl R30 is placed into the crystal structure of p65 predicts new van der Waals contacts that stabilize intraprotein interactions and indirectly increase the affinity of p65 for DNA. PRMT5 was the only arginine methyltransferase that coprecipitated with p65, and its overexpression increased NF-κB activity, whereas PRMT5 knockdown had the opposite effect. Microarray analysis revealed that ∼85% of the NF-κB-inducible genes that are down-regulated by the R30A mutation are similarly down-regulated by knocking PRMT5 down. Many cytokine and chemokine genes are among these, and conditioned media from cells expressing the R30A mutant of p65 had much less NF-κB-inducing activity than media from cells expressing the wild-type protein. PRMT5 is overexpressed in many types of cancer, often to a striking degree, indicating that high levels of this enzyme may promote tumorigenesis, at least in part by facilitating NF-κB-induced gene expression.histone | mass spectrometry T he NF-κB family is comprised of two protein subfamilies: c-Rel, RelB, and RelA (p65), which include transactivation domains in their C termini, and p100 (p52) and p105 (p50), which include a number of ankyrin repeats in their C termini and have transrepressive functions. All family members include an N-terminal DNA-binding region, the Rel homology domain (1). In the absence of an activating stimulus, NF-κB is located in the cytoplasm in a complex with the inhibitory IκB protein. In the classic pathway of NF-κB activation, extracellular signals activate IκB kinase, which phosphorylates IκBα, leading to its ubiquitination and degradation by proteasomes. NF-κB, liberated from IκB, translocates to the nucleus to regulate its target genes (2). The NF-κB pathway is regulated by means of several different posttranslational modifications, including ubiquitination, phosphorylation, acetylation, sumoylation, and nitrosylation (3). The recent work of several laboratories has revealed the reversible methylation of nonhistone proteins by enzymes that were discovered on the basis of their activities toward histones. For NF-κB, we found that in response to an activating signal, such as treatment with IL-1β, the p65 subunit is reversibly methylated on two specific lysine residues by chromatin remodeling enzymes in ways that profoundly aff...

The sulfhydration of cysteine residues in proteins is an important mechanism involved in diverse biological processes. We have developed a proteomics approach to quantitatively profile the changes of sulfhydrated cysteines in biological systems. Bioinformatics analysis revealed that sulfhydrated cysteines are part of a wide range of biological functions. In pancreatic β cells exposed to endoplasmic reticulum (ER) stress, elevated H2S promotes the sulfhydration of enzymes in energy metabolism and stimulates glycolytic flux. We propose that transcriptional and translational reprogramming by the integrated stress response (ISR) in pancreatic β cells is coupled to metabolic alternations triggered by sulfhydration of key enzymes in intermediary metabolism.DOI: http://dx.doi.org/10.7554/eLife.10067.001

Cancer cells often require glutamine for growth, thereby distinguishing them from most normal cells. Here we show that PIK3CA mutations reprogram glutamine metabolism by upregulating glutamate pyruvate transaminase 2 (GPT2) in colorectal cancer (CRC) cells, making them more dependent on glutamine. Compared with isogenic wild-type (WT) cells, PIK3CA mutant CRCs convert substantially more glutamine to α-ketoglutarate to replenish the tricarboxylic acid cycle and generate ATP. Mutant p110α upregulates GPT2 gene expression through an AKT-independent, PDK1–RSK2–ATF4 signalling axis. Moreover, aminooxyacetate, which inhibits the enzymatic activity of aminotransferases including GPT2, suppresses xenograft tumour growth of CRCs with PIK3CA mutations, but not with WT PIK3CA. Together, these data establish oncogenic PIK3CA mutations as a cause of glutamine dependency in CRCs and suggest that targeting glutamine metabolism may be an effective approach to treat CRC patients harbouring PIK3CA mutations.