Thirty-nine patients with chronic HBV infection and 38 normal persons were investigated by simultaneous assay of T suppressor cell function and enumeration of T-lymphocyte subsets by monoclonal antibodies. In patients with chronic active hepatitis B (CAH-B), T suppressor cell activity (17.8 +/- 8.8%) was significantly lower than in healthy HBsAg carriers (35.4 +/- 12.3%) and normal control persons (38.3 +/- 16.3%). The proportions of T-lymphocyte subsets in patients with CAH-B were not different from those of healthy HBsAg carriers and control persons. No correlation was observed in between percentage suppression and proportions of T-lymphocyte subsets. These findings suggest that in the absence of a simultaneous assay of function, enumeration of T-lymphocyte subsets by using monoclonal antibodies is an inadequate assessment of immune regulation.

The Hippo pathway controls organ size and tissue homeostasis, and its dysregulation often contributes to tumorigenesis. Extensive studies have shown that the Hippo pathway inhibits cell proliferation, and survival in a cell-autonomous manner. We examined the function of the Hippo pathway kinases LATS1/2 (large tumor suppressor 1 and 2) in cancer cells. As expected, loss of LATS1/2 promotes cancer cell growth in most cell lines. Surprisingly, however, LATS1/2 deletion inhibits the growth of murine MC38 colon cancer cells, especially under detachment conditions. This growth inhibitory effect caused by LATS1/2 deletion is due to uncontrolled activation of Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), the key downstream transcriptional coactivators inhibited by LATS1/2. We identified Wnt inducible signaling pathway protein 2 (Wisp2) and coiled-coil domain containing 80 (Ccdc80) as direct targets of YAP/TAZ. Their expression is selectively induced by LATS1/2 deletion in MC38 cells. Furthermore, deletion of WISP2 and CCDC80 prevents the growth inhibitory effect of LATS1/2 loss in MC38 cells. Our study demonstrates that the function of LATS1/2 in cell growth is cell context dependent, suggesting that LATS1/2 inhibition can be a therapeutic approach for some cancer types.

Yes-associated protein (YAP) and its homolog transcriptional coactivator with PDZ-binding motif (TAZ) are key effectors of the Hippo pathway to control cell growth and organ size, of which dysregulation yields to tumorigenesis or hypertrophy. Upon activation, YAP/TAZ translocate into the nucleus and bind to TEAD transcription factors to promote transcriptional programs for proliferation or cell specification. Immediate early genes, represented by AP-1 complex, are rapidly induced and control later-phase transcriptional program to play key roles in tumorigenesis and organ maintenance. Here, we report that YAP/TAZ directly promote FOS transcription that in turn contributes to the biological function of YAP/TAZ. YAP/TAZ bind to the promoter region of FOS to stimulate its transcription. Deletion of YAP/TAZ blocks the induction of immediate early genes in response to mitogenic stimuli. FOS induction contributes to expression of YAP/TAZ downstream target genes. Genetic deletion or chemical inhibition of AP-1 suppresses growth of YAP-driven cancer cells, such as Lats1/2-deficient cancer cells as well as Gα_q/11 mutated uveal melanoma. Furthermore, AP-1 inhibition almost completely abrogates the hepatomegaly induced by YAP overexpression. Our findings reveal a feed-forward interplay between immediate early transcription of AP-1 and Hippo pathway function.

Nonalcoholic fatty liver disease (NAFLD) arises from mitochondrial dysfunction under sustained imbalance between energy intake and expenditure, but the underlying mechanisms controlling mitochondrial respiration have not been entirely understood. Heterotrimeric G proteins converge with activated GPCRs to modulate cell-signaling pathways to maintain metabolic homeostasis. Here, we investigated the regulatory role of G protein α12 (Gα12) on hepatic lipid metabolism and whole-body energy expenditure in mice. Fasting increased Gα12 levels in mouse liver. Gα12 ablation markedly augmented fasting-induced hepatic fat accumulation. cDNA microarray analysis from Gna12-KO liver revealed that the Gα12-signaling pathway regulated sirtuin 1 (SIRT1) and PPARα, which are responsible for mitochondrial respiration. Defective induction of SIRT1 upon fasting was observed in the liver of Gna12-KO mice, which was reversed by lentivirus-mediated Gα12 overexpression in hepatocytes. Mechanistically, Gα12 stabilized SIRT1 protein through transcriptional induction of ubiquitin-specific peptidase 22 (USP22) via HIF-1α increase. Gα12 levels were markedly diminished in liver biopsies from NAFLD patients. Consistently, Gna12-KO mice fed a high-fat diet displayed greater susceptibility to diet-induced liver steatosis and obesity due to decrease in energy expenditure. Our results demonstrate that Gα12 regulates SIRT1-dependent mitochondrial respiration through HIF-1α-dependent USP22 induction, identifying Gα12 as an upstream molecule that contributes to the regulation of mitochondrial energy expenditure.

Ten-eleven translocation (TET) enzymes mediate the conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), which is enriched in brain, and its ultimate DNA demethylation. However, the influence of TET and 5hmC on gene transcription in brain remains elusive. We found that ten-eleven translocation protein 1 (TET1) was downregulated in mouse nucleus accumbens (NAc), a key brain reward structure, by repeated cocaine administration, which enhanced behavioral responses to cocaine. We then identified 5hmC induction in putative enhancers and coding regions of genes that have pivotal roles in drug addiction. Such induction of 5hmC, which occurred similarly following TET1 knockdown alone, correlated with increased expression of these genes as well as with their alternative splicing in response to cocaine administration. In addition, 5hmC alterations at certain loci persisted for at least 1 month after cocaine exposure. Together, these reveal a previously unknown epigenetic mechanism of cocaine action and provide new insight into how 5hmC regulates transcription in brain in vivo.

Nonalcoholic fatty liver disease (NAFLD) arises from mitochondrial dysfunction under sustained imbalance between energy intake and expenditure, but the underlying mechanisms controlling mitochondrial respiration have not been entirely understood. Heterotrimeric G proteins converge with activated GPCRs to modulate cell-signaling pathways to maintain metabolic homeostasis. Here, we investigated the regulatory role of G protein α12 (Gα12) on hepatic lipid metabolism and whole-body energy expenditure in mice. Fasting increased Gα12 levels in mouse liver. Gα12 ablation markedly augmented fasting-induced hepatic fat accumulation. cDNA microarray analysis from Gna12-KO liver revealed that the Gα12-signaling pathway regulated sirtuin 1 (SIRT1) and PPARα, which are responsible for mitochondrial respiration. Defective induction of SIRT1 upon fasting was observed in the liver of Gna12-KO mice, which was reversed by lentivirus-mediated Gα12 overexpression in hepatocytes. Mechanistically, Gα12 stabilized SIRT1 protein through transcriptional induction of ubiquitin-specific peptidase 22 (USP22) via HIF-1α increase. Gα12 levels were markedly diminished in liver biopsies from NAFLD patients. Consistently, Gna12-KO mice fed a high-fat diet displayed greater susceptibility to diet-induced liver steatosis and obesity due to decrease in energy expenditure. Our results demonstrate that Gα12 regulates SIRT1-dependent mitochondrial respiration through HIF-1α-dependent USP22 induction, identifying Gα12 as an upstream molecule that contributes to the regulation of mitochondrial energy expenditure.

Background

Crohn's disease (CD) is an intractable inflammatory bowel disease of unknown cause. Recent genome-wide association studies of CD in Korean and Japanese populations suggested marginal sharing of susceptibility loci between Caucasian and Asian populations. As the 7 identified loci altogether explain 5.31% of the risk for CD, the objective of this study was to identify additional CD susceptibility loci in the Korean population.

Methods

Using the ImmunoChip custom single-nucleotide polymorphism array designed for dense genotyping of 186 loci identified through GWAS, we analyzed 722 individuals with CD and 461 controls for 96,048 SNP markers in the discovery stage, followed by validation in an additional 948 affected individuals and 977 controls.

Results

We confirmed 6 previously reported loci in Caucasian: GPR35 at 2q37 (rs3749172; P = 5.30 × 10, odds ratio [OR] = 1.45), ZNF365 at 10q21 (rs224143; P = 2.20 × 10, OR = 1.38), ZMIZ1 at 10q22 (rs1250569; P = 3.05 × 10, OR = 1.30), NKX2-3 at 10q24 (rs4409764; P = 7.93 × 10, OR = 1.32), PTPN2 at 18p11 (rs514000; P = 9.00 × 10, OR = 1.33), and USP25 at 21q11 (rs2823256; P = 2.49 × 10, OR = 1.35), bringing the number of known CD loci (including 3 in the HLA) in Koreans to 15. The 6 additional loci increased the total genetic variance for CD risk from 5.31% to 7.27% in Koreans.

Conclusions

Although the different genetic backgrounds of CD between Asian and Western countries has been well established for the major susceptibility genes, our findings of overlapping associations offer new insights into the genetic architecture of CD.

Despite abundant expression of DNA methyltransferases (Dnmts) in brain, the regulation and behavioral role of DNA methylation remain poorly understood. We found that Dnmt3a expression was regulated in mouse nucleus accumbens (NAc) by chronic cocaine use and chronic social defeat stress. Moreover, NAc-specific manipulations that block DNA methylation potentiated cocaine reward and exerted antidepressant-like effects, whereas NAc-specific Dnmt3a overexpression attenuated cocaine reward and was pro-depressant. On a cellular level, we found that chronic cocaine use selectively increased thin dendritic spines on NAc neurons and that DNA methylation was both necessary and sufficient to mediate these effects. These data establish the importance of Dnmt3a in the NAc in regulating cellular and behavioral plasticity to emotional stimuli.