Enhanced de novo lipogenesis mediated by sterol regulatory element-binding proteins (SREBPs) is thought to be involved in nonalcoholic steatohepatitis (NASH) pathogenesis. In this study, we assessed the impact of SREBP inhibition on NASH and liver cancer development in murine models. Unexpectedly, SREBP inhibition via deletion of the SREBP cleavage-activating protein (SCAP) in the liver exacerbated liver injury, fibrosis, and carcinogenesis, despite markedly reduced hepatic steatosis. These phenotypes were ameliorated by restoring SREBP function. Transcriptome and lipidome analyses revealed that SCAP–SREBP pathway inhibition altered the fatty acid (FA) composition of phosphatidylcholines due to both impaired FA synthesis and disorganized FA incorporation into phosphatidylcholine via lysophosphatidylcholine acyltransferase 3 (LPCAT3) downregulation, which led to endoplasmic reticulum (ER) stress and hepatocyte injury. Supplementation of phosphatidylcholines significantly improved liver injury and ER stress induced by SCAP deletion. The activity of SCAP-SREBP-LPCAT3 axis was found inversely associated with liver fibrosis severity in human NASH. SREBP inhibition also cooperated with impaired autophagy to trigger liver injury. Thus, excessively strong and broad lipogenesis inhibition was counterproductive for NASH therapy, which will have important clinical implications in NASH treatment.
Satoshi Kawamura, Yuki Matsushita, Shigeyuki Kurosaki, Mizuki Tange, Naoto Fujiwara, Yuki Hayata, Yoku Hayakawa, Nobumi Suzuki, Masahiro Hata, Mayo Tsuboi, Takahiro Kishikawa, Hiroto Kinoshita, Takuma Nakatsuka, Masaya Sato, Yotaro Kudo, Yujin Hoshida, Atsushi Umemura, Akiko Eguchi, Tsuneo Ikenoue, Yoshihiro Hirata, Motonari Uesugi, Ryosuke Tateishi, Keisuke Tateishi, Mitsuhiro Fujishiro, Kazuhiko Koike, Hayato Nakagawa
Gastric carcinogenesis is mediated by complex interactions among Helicobacter pylori, host, and environmental factors. We now demonstrate that H. pylori augments gastric injury in INS-GAS mice under iron deficient conditions. Mechanistically, these phenotypes were not driven by alterations in the gastric microbiota; however, discovery-based and targeted metabolomics revealed that bile acids were significantly altered in H. pylori-infected mice with iron deficiency, with significant upregulation of deoxycholic acid (DCA), a carcinogenic bile acid. Severity of gastric injury was further augmented when H. pylori-infected mice were treated with DCA, and, in vitro, DCA increased translocation of the H. pylori oncoprotein CagA into host cells. Conversely, bile acid sequestration attenuated H. pylori-induced injury under conditions of iron deficiency. To translate these findings into human populations, the association between bile acid-sequestrant use and gastric cancer risk was evaluated in a large human cohort. Among 416,885 individuals, a significant dose-dependent reduction in risk was associated with cumulative bile acid-sequestrant use. Further, expression of the bile acid receptor TGR5 paralleled the severity of carcinogenic lesions in humans. These data demonstrate that increased H. pylori-induced injury within the context of iron deficiency is tightly linked to altered bile acid metabolism, which may promote gastric carcinogenesis.
Jennifer M. Noto, M. Blanca Piazuelo, Shailja C. Shah, Judith Romero-Gallo, Jessica L. Hart, Chao Di, James D. Carmichael, Alberto G. Delgado, Alese E. Halvorson, Robert A. Greevy, Jr., Lydia E. Wroblewski, Ayushi Sharma, Annabelle B. Newton, Margaret M. Allaman, Keith T. Wilson, M. Kay Washington, M. Wade Calcutt, Kevin L. Schey, Bethany P. Cummings, Charles R. Flynn, Joseph P. Zackular, Richard M. Peek, Jr.
De novo and acquired resistance are major impediments to the efficacy of conventional and targeted cancer therapy. In unselected gastric cancer (GC) patients with advanced disease, trials combining chemotherapy and an anti-EGFR monoclonal antibody have been largely unsuccessful. In an effort to identify biomarkers of resistance so as to better select patients for such trials, we screened the secretome of chemotherapy-treated human GC cell lines. We found that levels of CGA, the α-subunit of glycoprotein hormones, were markedly increased in the conditioned media of chemoresistant GC cells, and CGA immunoreactivity was enhanced in GC tissues that progressed on chemotherapy. CGA levels in plasma increased in GC patients who received chemotherapy, and this increase was correlated with reduced responsiveness to chemotherapy and poor survival. Mechanistically, secreted CGA was found to bind to EGFR and activate EGFR signaling, thereby conferring a survival advantage to GC cells. N-glycosylation of CGA at Asn52 and Asn78 is required for its stability, secretion, and interaction with EGFR. GATA2 was found to activate CGA transcription, whose increase, in turn, induced the expression and phosphorylation of GATA2 in an EGFR-dependent manner, forming a positive feedback circuit that was initiated by GATA2 autoregulation upon sublethal exposure to chemotherapy. Based on this circuit, combination strategies involving anti-EGFR therapies or targeting CGA with microRNAs (miR-708-3p and miR-761) restored chemotherapy sensitivity. These findings identify a clinically actionable CGA/EGFR/GATA2 circuit and highlight CGA as a predictive biomarker and therapeutic target in chemoresistant GC.
Tianyu Cao, Yuanyuan Lu, Qi Wang, Hongqiang Qin, Hongwei Li, Hao Guo, Minghui Ge, Sarah E. Glass, Bhuminder Singh, Wenyao Zhang, Jiaqiang Dong, Feng Du, Airong Qian, Ye Tian, Xin Wang, Cunxi Li, Kaichun Wu, Daiming Fan, Yongzhan Nie, Robert J. Coffey, Xiaodi Zhao
The striatin-interacting phosphatase and kinase (STRIPAK) complexes integrate extracellular stimuli to result in intracellular activities. Previously, we discovered STRIPAK to be a key machinery responsible for loss of the Hippo tumor suppressor signal in cancer. Here, we identified the Hippo-STRIPAK complex to be an essential player for the control of DNA double-strand break (DSB) repair and genomic stability. Specifically, the MST1/2 kinases were found, independent of the classical Hippo signaling, to directly phosphorylate ZMYND8 and hence result in suppression of DNA repair in the nucleus. In response to genotoxic stress, the cGAS-STING pathway was determined to relay nuclear DNA damage signals to the dynamic assembly of Hippo-STRIPAK via a TBK1-induced structural stabilization of the SIKE1-SLMAP arm. As such, STRIPAK-mediated MST1/2 inactivation was found to increase the DSB repair capacity of cancer cells and to endow these cells with resistance to radio/chemotherapy and PARP inhibition. Importantly, targeting the STRIPAK assembly with each of three distinct peptide inhibitors efficiently recovered the kinase activity of MST1/2 to suppress DNA repair and re-sensitize cancer cells to PARPi in both animal and patient-derived tumor models. Overall, our findings not only uncovered a previously unrecognized role for STRIPAK in modulating DSB repair, but also provided translational implications of co-targeting STRIPAK and PARP for a new type of synthetic lethality anti-cancer therapy.
Liwei An, Zhifa Cao, Pingping Nie, Hui Zhang, Zhenzhu Tong, Fan Chen, Yang Tang, Yi Han, Wenjia Wang, Zhangting Zhao, Qingya Zhao, Yuqin Yang, Yuanzhi Xu, Gemin Fang, Lei Shi, Huixiong Xu, Haiqing Ma, Shi Jiao, Zhaocai Zhou
Gastrointestinal motility disorders involve alterations to the structure and/or function of the enteric nervous system (ENS) but the causal mechanisms remain unresolved in most cases. Homeostasis and disease in the ENS are processes that are regulated by enteric glia. Signaling mediated through type I lysophosphatidic acid receptors (LPAR1) has recently emerged as an important mechanism that contributes to disease, in part, through effects on peripheral glial survival and function. Enteric glia express LPAR1 but its role in ENS function and motility disorders is unknown. We used a combination of genetic, immunohistochemical, calcium imaging, and in vivo pharmacological approaches to investigate the role of LPAR1 in enteric glia. LPAR1 was enriched in enteric glia in mice and humans and LPA stimulated intracellular calcium responses in enteric glia, subsequently recruiting activity in a subpopulation of myenteric neurons. Blocking LPAR1 in vivo with AM966 attenuated gastrointestinal motility in mice and produced marked enteric neuro- and gliopathy. Samples from humans with chronic intestinal pseudo-obstruction (CIPO), a severe motility disorder, showed reduced glial LPAR1 expression in the colon and ileum. These data suggest that enteric glial LPAR1 signaling regulates gastrointestinal motility through enteric glia and could contribute to severe motility disorders in humans such as CIPO.
Mohammad M. Ahmadzai, Jonathon L. McClain, Christine Dharshika, Luisa Seguella, Fiorella Giancola, Roberto De Giorgio, Brian D. Gulbransen
Anti-TNF antibodies are effective for treating patients with inflammatory bowel disease (IBD), but many patients fail to respond to anti-TNF therapy, highlighting the importance of TNF-independent disease. We previously demonstrated that acute deletion of two IBD susceptibility genes, A20 (Tnfaip3) and Abin-1 (Tnip1), in intestinal epithelial cells (IECs) sensitized mice to both TNF-dependent and TNF-independent death. Here we show that TNF-independent IEC death after A20 and Abin-1 deletion was rescued by germ-free derivation or deletion of MyD88, while deletion of Trif provided only partial protection. Combined deletion of Ripk3 and Casp8, which inhibits both apoptotic and necroptotic death, completely protected against death after acute deletion of A20 and Abin-1 in IECs. A20 and Abin-1-deficient IECs were sensitized to TNF-independent, TNFR-1-mediated death in response to lymphotoxin alpha (LT⍺) homotrimers. Blockade of LT⍺ in vivo reduced weight loss and improved survival when combined with partial deletion of MyD88. Biopsies of inflamed colon mucosa from patients with IBD exhibited increased LTA and IL1B expression, including a subset of patients with active colitis on anti-TNF therapy. These data show that microbial signals, MyD88, and LT⍺ all contribute to TNF-independent intestinal injury.
Iulia Rusu, Elvira Mennillo, Jared L. Bain, Zhongmei Li, Xiaofei Sun, Kimberly M. Ly, Yenny Y. Rosli, Mohammad Naser, Zunqiu Wang, Rommel Advincula, Philip Achacoso, Ling Shao, Bahram Razani, Ophir D. Klein, Alexander Marson, Jessie A. Turnbaugh, Peter J. Turnbaugh, Barbara A. Malynn, Averil Ma, Michael G. Kattah
Functional gastrointestinal disorders (FGIDs) have prominent sex differences in incidence, symptoms, and treatment response that are not well understood. Androgens are steroid hormones present at much higher levels in males than females and could be involved in these differences. In adults with irritable bowel syndrome (IBS), a FGID that affects 5-10% of the population worldwide, we found that free testosterone levels were lower than those in healthy controls and inversely correlated with symptom severity. To determine how this diminished androgen signaling could contribute to bowel dysfunction, we depleted gonadal androgens in adult mice and found that this caused a profound deficit in gastrointestinal transit. Restoring a single androgen hormone was sufficient to rescue this deficit, suggesting that circulating androgens are essential for normal bowel motility in vivo. To determine the site of action, we probed androgen receptor expression in the intestine and discovered, unexpectedly, that a large subset of enteric neurons became androgen-responsive upon puberty. Androgen signaling to these neurons was required for normal colonic motility in adult mice. Taken together, these observations establish a role for gonadal androgens in the neural regulation of bowel function and link altered androgen levels with a common digestive disorder.
Daniella Rastelli, Ariel Robinson, Valentina N. Lagomarsino, Lynley T. Matthews, Rafla Hassan, Kristina Perez, William Dan, Peter D. Yim, Madison Mixer, Aleksandra Prochera, Amy Shepherd, Liang Sun, Kathryn Hall, Sarah Ballou, Anthony Lembo, Judy Nee, Meenakshi Rao
Bitter taste receptors (TAS2R) serve as warning sensors in the lingual system against ingestion of potential poisonous food. Here, we investigated the functional role of TAS2Rs in the human gut and focused on their potential to trigger an additional host defense pathway in the intestine. Human jejunal crypts, especially from obese subjects, responded to bitter agonists by inducing the release of antimicrobial peptides (α-defensin 5 and REG3A) but also regulated the expression of other innate immune factors (mucins, chemokines) that affected E. coli growth. The effect of aloin on E. coli growth and on the release of the mucus glycoprotein CLCA1, identified via proteomics, was affected by TAS2R43 amino acid/deletion polymorphisms and thus confirmed a role for TAS2R43. RNA sequencing uncovered that denatonium benzoate induced an NRF2-mediated nutrient stress response and an unfolded protein response that increased the expression of the mitokine GDF15 but also ADM2 and the LDLR, genes that are involved in anorectic signaling and lipid homeostasis. To conclude, TAS2Rs in the intestine provide a promising target for treating diseases that involve disturbances in the innate immune system and in body weight control. Polymorphisms in TAS2Rs may be valuable genetic markers to predict therapeutic responses.
Kathrin I. Liszt, Qiaoling Wang, Mona Farhadipour, Anneleen Segers, Theo Thijs, Linda Nys, Ellen Deleus, Bart Van der Schueren, Christopher Gerner, Benjamin Neuditschko, Laurens J. Ceulemans, Matthias Lannoo, Jan Tack, Inge Depoortere
Emerging evidence has shown that open reading frames inside lncRNA could encode micropeptides. However, their roles in cellular energy metabolism and tumor progression remain largely unknown. Here, we identified a 94-amino acid-length micropeptide encoded by lncRNA LINC00467 in colorectal cancer. We also characterized its conservation across higher mammals, localization to mitochondria, and the concerted local functions. This peptide enhanced the ATP synthase construction by interacting with the subunit α and γ (ATP5A and ATP5C), increased ATP synthase activity and mitochondrial oxygen consumption rate, and thereby promoted colorectal cancer cell proliferation. Hence, this micropeptide was termed as “ATP synthase associated peptide” (ASAP). Furthermore, loss of ASAP suppressed patient-derived xenograft growth with attenuated ATP synthase activity and mitochondrial ATP production. Clinically, high expression of ASAP and LINC00467 predicted poor prognosis of colorectal cancer patients. Taken together, our findings revealed a colorectal cancer-associated micropeptide as a vital player in mitochondrial metabolism and provided a therapeutic target for colorectal cancer.
Qiwei Ge, Dingjiacheng Jia, Dong Cen, Yadong Qi, Chengyu Shi, Junhong Li, Lingjie Sang, Luo-jia Yang, Jiamin He, Aifu Lin, Shujie Chen, Liangjing Wang
Genome-wide association studies revealed that loss-of-function mutations in protein tyrosine phosphatase non-receptor type 2 (PTPN2) increase the risk of developing chronic immune diseases, such as inflammatory bowel disease (IBD) and celiac disease. These conditions are associated with increased intestinal permeability as an early etiological event. The aim of this study was to examine the consequences of deficient activity of the PTPN2 gene product, T cell protein tyrosine phosphatase (TCPTP), on intestinal barrier function and tight junction organization in vivo and in vitro. Here, we demonstrate that TCPTP protected against intestinal barrier dysfunction induced by the inflammatory cytokine IFN-γ by 2 mechanisms: it maintained localization of zonula occludens 1 and occludin at apical tight junctions and restricted both expression and insertion of the cation pore-forming transmembrane protein, claudin-2, at tight junctions through upregulation of the inhibitory cysteine protease, matriptase. We also confirmed that the loss-of-function PTPN2 rs1893217 SNP was associated with increased intestinal claudin-2 expression in patients with IBD. Moreover, elevated claudin-2 levels and paracellular electrolyte flux in TCPTP-deficient intestinal epithelial cells were normalized by recombinant matriptase. Our findings uncover distinct and critical roles for epithelial TCPTP in preserving intestinal barrier integrity, thereby proposing a mechanism by which PTPN2 mutations contribute to IBD.
Ronald R. Marchelletta, Moorthy Krishnan, Marianne R. Spalinger, Taylaur W. Placone, Rocio Alvarez, Anica Sayoc-Becerra, Vinicius Canale, Ali Shawki, Young Su Park, Lucas H.P. Bernts, Stephen Myers, Michel L. Tremblay, Kim E. Barrett, Evan Krystofiak, Bechara Kachar, Dermot P.B. McGovern, Christopher R. Weber, Elaine M. Hanson, Lars Eckmann, Declan F. McCole