Concurrent activation of growth factor and nutrient arms of mTORC1 induces oxidative liver injury.

mTORC1 is a protein kinase important for metabolism and is regulated by growth factor and nutrient signaling pathways, mediated by the Rheb and Rag GTPases, respectively. Here we provide the first animal model in which both pathways were upregulated through concurrent mutations in their GTPase-activating proteins, Tsc1 and Depdc5. Unlike former models that induced limited mTORC1 upregulation, hepatic deletion of both Tsc1 and Depdc5 (DKO) produced strong, synergistic activation of the mTORC1 pathway and provoked pronounced and widespread hepatocyte damage, leading to externally visible liver failure phenotypes, such as jaundice and systemic growth defects. The transcriptome profile of DKO was different from single knockout mutants but similar to those of diseased human livers with severe hepatitis and mouse livers challenged with oxidative stress-inducing chemicals. In addition, DKO liver cells exhibited prominent molecular pathologies associated with excessive endoplasmic reticulum (ER) stress, oxidative stress, DNA damage and inflammation. Although DKO liver pathologies were ameliorated by mTORC1 inhibition, ER stress suppression unexpectedly aggravated them, suggesting that ER stress signaling is not the major conduit of how hyperactive mTORC1 produces liver damage. Interestingly, superoxide scavengers N-acetylcysteine (NAC) and Tempol, chemicals that reduce oxidative stress, were able to recover liver phenotypes, indicating that mTORC1 hyperactivation induced liver damage mainly through oxidative stress pathways. Our study provides a new model of unregulated mTORC1 activation through concomitant upregulation of growth factor and nutrient signaling axes and shows that mTORC1 hyperactivation alone can provoke oxidative tissue injury.

Zingiber officinale extract and omega-3 fatty acids ameliorate endoplasmic reticulum stress in a nonalcoholic fatty liver rat model.

Endoplasmic reticulum (ER) stress was reported to play a major role in non-alcoholic fatty liver disease (NAFLD) induction and progression. Here, we study the effect of Zingiber officinale and omega-3 fatty acids on ER stress for treating NAFLD. Male Wistar rats were fed on a normal diet (control group) or high-fat diet (HFD) for 8 weeks. The HFD rats were later treated with vehicle, omega-3 or with Z. officinale extract. HFD group demonstrated significantly more body weight gain and higher plasma lipid profile, glucose, and hepatic enzymes. The expressions of lipogenic ChREBP and ER stress genes CHOP, XBP1, and GRP78 were increased. This was accompanied by intrahepatic fat accumulation visualized by hepatic morphology and H&E-stained sections. Treatment with Z. officinale and omega-3 fatty acids reverted these changes into a normal healthy state. From these results, we prove that both therapeutic approaches can be potential drugs for treating NAFLD besides other ER stress-associated diseases. PRACTICAL APPLICATIONS: The effect of Zingiber officinale extract and omega-3 fatty acid on ER stress associated with NAFLD was investigated. The results revealed that Z. officinale extract and omega-3 fatty acids significantly inhibited ER stress and intrahepatic fat accumulation with the upper hand for Z. officinale extract. Both can be used as future promising therapies for the treatment of NAFLD patients and also treating different diseases that involve ER stress as a pathological modulator like diabetes mellitus, Alzheimer's disease, Parkinson's disease, and cancer.

Whole exome sequencing as a diagnostic tool for patients with ciliopathy-like phenotypes.

Ciliopathies are a group of rare disorders characterized by a high genetic and phenotypic variability, which complicates their molecular diagnosis. Hence the need to use the latest powerful approaches to faster identify the genetic defect in these patients. We applied whole exome sequencing to six consanguineous families clinically diagnosed with ciliopathy-like disease, and for which mutations in predominant Bardet-Biedl syndrome (BBS) genes had previously been excluded. Our strategy, based on first applying several filters to ciliary variants and using many of the bioinformatics tools available, allowed us to identify causal mutations in BBS2, ALMS1 and CRB1 genes in four families, thus confirming the molecular diagnosis of ciliopathy. In the remaining two families, after first rejecting the presence of pathogenic variants in common cilia-related genes, we adopted a new filtering strategy combined with prioritisation tools to rank the final candidate genes for each case. Thus, we propose CORO2B, LMO7 and ZNF17 as novel candidate ciliary genes, but further functional studies will be needed to confirm their role. Our data show the usefulness of this strategy to diagnose patients with unclear phenotypes, and therefore the success of applying such technologies to achieve a rapid and reliable molecular diagnosis, improving genetic counselling for these patients. In addition, the described pipeline also highlights the common pitfalls associated to the large volume of data we have to face and the difficulty of assigning a functional role to these changes, hence the importance of designing the most appropriate strategy according to each case.