Oral Supplementation with Betaine Powder Ameliorated High Blood Pressure in Spontaneously Hypertensive Rats.

Supplementation of betaine is associated with improved cardiac health, potentially due to its function in re-methylation of homocysteine, an independent risk factor for cardiovascular diseases. We investigated the effects of oral betaine supplementation on blood pressure homeostasis in spontaneously hypertensive (SHR) rats and Wistar Kyoto (WKY) rats in an 8 week-feeding trial with control (SHR-con and WKY-con) and 1% betaine supplemented (SHR-b and WKY-b) diets. Systolic, diastolic, and mean blood pressure in the SHR-b group were significantly lower at week 8 (p = 0.013, p = 0.011, p = 0.010, respectively). Furthermore, serum nitric oxide (NO) levels were significantly (p < 0.05) improved in the WKY-b and SHR-b groups, suggesting a healthy endothelial function. Additionally, the serum angiotensin I converting enzyme level in SHR-b rats was also significantly lowered, which may have been another reason for lower blood pressure. A significantly higher non-HDL level in the SHR-b group might reflect enhanced lipid secretion into the circulation in the form of very-low-density lipoprotein (VLDL). Betaine is known for its effect on the synthesis of phosphatidylcholine, a key component of VLDL. However, the long-term net outcomes of both blood pressure lowering and serum lipid increment should be further studied.

Temporal changes in the fermentation characteristics, bacterial community structure and the functionality of the predicted metagenome of a batch fermenter medium containing the upper gastrointestinal enzyme resistant fraction of white sorghum (Sorghum bicolor L. Moench).

Sorghum is a potential prebiotic ascribed to the high native resistant starch (RS) content. Our previous studies on raw sorghum have revealed prominent amino acid fermentation despite the high RS content. Interestingly, autoclaved-freeze-dried sorghum fed rats exhibited beneficial microbial and biochemical profiles. Having a keen interest to reciprocally scrutinize the underlying mechanisms behind these contrasting outcomes, we used an in vitro porcine batch fermentation model. The fermentable substrates in raw and autoclaved-freeze-dried (three cycles) sorghum (AC) after in vitro gastrointestinal digestion fostered similar bacterial community structures, yet with significant differences in the characteristic amylolytic microbial taxa abundance and their temporal variation. Further, significant differences in the concentration of organic acids in raw and AC manifested the differences in the predicted abundance of the underlying pathways of carbohydrate and organic acid metabolism. Thus, this study highlights the propensity of the heat-moisture treatment of sorghum in modifying the fermentability of its RS.

Development of combination therapies with BTK inhibitors and dasatinib to treat CNS-infiltrating E2A-PBX1+/preBCR+ ALL.

ABSTRACT: The t(1;19) translocation, encoding the oncogenic fusion protein E2A (TCF3)-PBX1, is involved in acute lymphoblastic leukemia (ALL) and associated with a pre-B-cell receptor (preBCR+) phenotype. Relapse in patients with E2A-PBX1+ ALL frequently occurs in the central nervous system (CNS). Therefore, there is a medical need for the identification of CNS active regimens for the treatment of E2A-PBX1+/preBCR+ ALL. Using unbiased short hairpin RNA (shRNA) library screening approaches, we identified Bruton tyrosine kinase (BTK) as a key gene involved in both proliferation and dasatinib sensitivity of E2A-PBX1+/preBCR+ ALL. Depletion of BTK by shRNAs resulted in decreased proliferation of dasatinib-treated E2A-PBX1+/preBCR+ cells compared with control-transduced cells. Moreover, the combination of dasatinib with BTK inhibitors (BTKi; ibrutinib, acalabrutinib, or zanubrutinib) significantly decreased E2A-PBX1+/preBCR+ human and murine cell proliferation, reduced phospholipase C gamma 2 (PLCG2) and BTK phosphorylation and total protein levels and increased disease-free survival of mice in secondary transplantation assays, particularly reducing CNS-leukemic infiltration. Hence, dasatinib with ibrutinib reduced pPLCG2 and pBTK in primary ALL patient samples, including E2A-PBX1+ ALLs. In summary, genetic depletion and pharmacological inhibition of BTK increase dasatinib effects in human and mouse with E2A-PBX1+/preBCR+ ALL across most of performed assays, with the combination of dasatinib and BTKi proving effective in reducing CNS infiltration of E2A-PBX1+/preBCR+ ALL cells in vivo.

Involvement of the vagus nerve and hepatic gene expression in serum adiponectin concentrations in mice.

Several humoral factors, such as adiponectin and urate, have been suggested to affect metabolic syndromes. Previously, we reported a reduction in blood adiponectin concentrations after a high-fructose diet partially via the vagus nerve in rats. Although a lithogenic diet (LD), i.e., supplementation of a normal control diet (CT) with 0.6% cholesterol and 0.2% sodium cholate, reduced blood adiponectin concentrations, the involvement of the vagus nerve in this mechanism remains unclear. To estimate the involvement of the vagus nerve in the regulation of blood adiponectin concentrations using an LD, male imprinting control region mice that had been vagotomized (HVx) or only laparotomized (Sham) were administered a CT or an LD for 10 weeks. Serum adiponectin concentrations in the Sham-LD, HVx-CT, and HVx-LD groups were reduced by half compared with the Sham-CT group. The hepatic mRNA levels of fibroblast growth factor 21 (Fgf21), which reportedly stimulates adiponectin secretion from white adipose tissue, were lower in the LD groups compared with the CT groups. HepG2 hepatoma cells showed that various bile acids reduced the mRNA expression of FGF21. Moreover, the LD increased serum urate concentrations and reduced hepatic expressions of the acyl-CoA oxidase 1 (Acox1) mRNA and glucokinase, suggesting insufficient regeneration of ATP from AMP. In conclusion, serum adiponectin concentration may be regulated via the vagus nerve in normal mice, whereas a reduction of hepatic Fgf21 mRNA by bile acids may also lower serum adiponectin levels. Moreover, the LD may promote hepatic AMP accumulation and subsequently increase the serum urate concentration in mice.

Understanding the mobile healthcare applications continuance: The regulatory focus perspective.

BACKGROUND: Although mobile healthcare (mHealth) applications have proliferated and offer new opportunities for personal health management, many users exhibit discontinuance behavior. Various factors in mHealth applications can strongly impact users' continuance behavior, but it is not yet fully understood how they interact with each other to yield maximized effects. This study highlights the importance of identifying the antecedents and moderators of continuance intention to broaden the demographic reach of mHealth applications and thus contribute to maintaining a sustainable healthcare system. OBJECTIVE: This research explores three dimensions of perceived values (hedonic, utilitarian, and social) in mHealth platforms that lead to user satisfaction and, ultimately, continuance intention. It further investigates the moderating effects of personal traits defined by regulatory focus on the relationship between perceived value and user satisfaction. METHODS: Data was collected from 259 respondents with experience using the Samsung Health application. The research tests the proposed model and hypotheses by implementing PLS-SEM and multi-group analyses. RESULTS: Each dimension of perceived values positively influences user satisfaction, with hedonic and utilitarian values exhibiting stronger relationships. Regarding moderating effects, promotion (versus prevention) focus has a stronger enhancing effect on the positive relationship between utilitarian value and user satisfaction. In contrast, prevention (versus promotion) focus more strongly enhances the positive relationship between hedonic value and user satisfaction. Regulatory focus does not yield a significant moderating effect on the relationship between social value and user satisfaction. User satisfaction exerts a strong positive influence on continuance intention in mHealth environments. CONCLUSIONS: The moderating effect of individuals' regulatory focus has been identified. Combined effects of antecedents and moderators on user satisfaction influence their continuance intention in mHealth ecologies. Considering individual users' characteristics may guide mHealth application developers to design personalized platforms and establish enforced marketing strategies.

Gut microbiota-derived lipid metabolites facilitate regulatory T cell differentiation.

Commensal bacteria-derived metabolites are critical in regulating the host immune system. Although the impact of gut microbiota-derived hydrophilic metabolites, such as short-chain fatty acids, on immune cell functions and development has been well documented, the immunomodulatory effects of gut microbiota-derived lipids are still of interest. Here, we report that lipid extracts from the feces of specific-pathogen-free (SPF), but not germ-free (GF), mice showed regulatory T (Treg)-cell-inducing activity. We conducted RP-HPLC-based fractionation and liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based lipidome profiling and identified two bioactive lipids, 9,10-dihydroxy-12Z-octadecenoic acid (9,10-DiHOME) and all-trans retinoic acid (atRA), with Treg-inducing activity in vitro. The luminal abundance of 9,10-DiHOME in the large intestine was significantly decreased by dextran sulfate sodium (DSS)-induced colitis, indicating that 9,10-DiHOME may be a potential biomarker of colitis. These observations implied that commensal bacteria-derived lipophilic metabolites might contribute to Treg development in the large intestine.

The N6-methyladenosine methyltransferase METTL16 enables erythropoiesis through safeguarding genome integrity.

During erythroid differentiation, the maintenance of genome integrity is key for the success of multiple rounds of cell division. However, molecular mechanisms coordinating the expression of DNA repair machinery in erythroid progenitors are poorly understood. Here, we discover that an RNA N6-methyladenosine (m6A) methyltransferase, METTL16, plays an essential role in proper erythropoiesis by safeguarding genome integrity via the control of DNA-repair-related genes. METTL16-deficient erythroblasts exhibit defective differentiation capacity, DNA damage and activation of the apoptotic program. Mechanistically, METTL16 controls m6A deposition at the structured motifs in DNA-repair-related transcripts including Brca2 and Fancm mRNAs, thereby upregulating their expression. Furthermore, a pairwise CRISPRi screen revealed that the MTR4-nuclear RNA exosome complex is involved in the regulation of METTL16 substrate mRNAs in erythroblasts. Collectively, our study uncovers that METTL16 and the MTR4-nuclear RNA exosome act as essential regulatory machinery to maintain genome integrity and erythropoiesis.

Beneficial health effects of polyphenols metabolized by fermentation.

High daily intake of polyphenol-rich meal in some countries could be regarded as a healthy meal. However, the knowledge about the bioavailability and functionality of the exiting amounts of polyphenol into the large intestine needs to be elucidated, particularly the beneficial health effects and its fermentation characteristics during fermentation. Thus, this review focuses on the influence of polyphenols metabolized by fermentation and elucidates their health attributes. Besides, it also summarized the potential benefits of polyphenols and discussed the need for further research to fully understand the health attributes of polyphenols.

Functional characterization of the PI3K/AKT/MTOR signaling pathway for targeted therapy in B-precursor acute lymphoblastic leukemia.

B-cell precursor acute lymphoblastic leukemias (B-ALL) are characterized by the activation of signaling pathways, which are involved in survival and proliferation of leukemia cells. Using an unbiased shRNA library screen enriched for targeting signaling pathways, we identified MTOR as the key gene on which human B-ALL E2A-PBX1+ RCH-ACV cells are dependent. Using genetic and pharmacologic approaches, we investigated whether B-ALL cells depend on MTOR upstream signaling pathways including PI3K/AKT and the complexes MTORC1 or MTORC2 for proliferation and survival in vitro and in vivo. Notably, the combined inhibition of MTOR and AKT shows a synergistic effect on decreased cell proliferation in B-ALL with different karyotypes. Hence, B-ALL cells were more dependent on MTORC2 rather than MTORC1 complex in genetic assays. Using cell metabolomics, we identified changes in mitochondrial fuel oxidation after shRNA-mediated knockdown or pharmacological inhibition of MTOR. Dependence of the cells on fatty acid metabolism for their energy production was increased upon inhibition of MTOR and associated upstream signaling pathways, disclosing a possible target for a combination therapy. In conclusion, B-ALL are dependent on the PI3K/AKT/MTOR signaling pathway and the combination of specific small molecules targeting this pathway appears to be promising for the treatment of B-ALL patients.

In vitro colonic fermentation characteristics of barley-koji differ from those of barley.

Barley-koji is prepared by inoculating barley, a beneficial prebiotic source, with the fungi Aspergillus luchuensis mut. kawachii. In this study, the prebiotic effects of barley-koji on human colonic microbiota were evaluated in vitro compared with barley, using pig feces. The enzyme-resistant fraction of the following sample groups each was added to respective fermenters: cellulose, barley (Commander and ß104), and barley-koji (Commander-koji and ß104-koji). Short-chain fatty acid and ammonia-nitrogen production increased and decreased, respectively, in barley-koji and barley groups. Furthermore, the propionate concentration increased in the barley group, showing a positive correlation with the abundance of the genus Dialister. In the barley-koji group, however, acetate and n-butyrate concentrations increased during the early stages of incubation, and the relative abundance of the genus Megasphaera was higher than those of the other genera. Therefore, this study demonstrated that barley-koji might possess beneficial physiological properties for colonic fermentation, which differ from those of barley.

Dietary Ethanolamine Plasmalogen Alleviates DSS-Induced Colitis by Enhancing Colon Mucosa Integrity, Antioxidative Stress, and Anti-inflammatory Responses via Increased Ethanolamine Plasmalogen Molecular Species: Protective Role of Vinyl Ether Linkages.

Dietary ethanolamine plasmalogen (PlsEtn) has been reported to have several health benefits; however, its functional role during colon pathophysiology remains elusive. The present study investigated the anticolitis effect of dietary ethanolamine glycerophospholipids (EtnGpls) with high PlsEtn from ascidian muscle (86.2 mol %) and low PlsEtn from porcine liver (7.7 mol %) in dextran sulfate sodium (DSS)-induced colitis in mice. Dietary EtnGpls lowered myeloperoxidase activity, thiobarbituric acid-reactive substances, proinflammatory cytokines and proapoptosis-related protein levels in colon mucosa after 16 days of DSS treatment, with ascidian muscle (0.1% EtnGpl in diet) showing higher suppression than porcine liver (0.1% EtnGpl in diet). Moreover, dietary EtnGpls suppressed DSS symptoms after 38 days of DSS treatment as evidenced by increased body weight, colon length, and ameliorated colon mucosa integrity. Additionally, dietary EtnGpls elevated short-chain fatty acid production in DSS-treated mice. Altogether, these results indicate the potential of utilizing diets with abundant PlsEtn for the prevention of colon inflammation-related disorders.

Combined effects of BARLEYmax and cocoa polyphenols on colonic microbiota and bacterial metabolites in vitro.

BARLEYmax, a barley variety, and cocoa polyphenols (CPPs) have been reported to affect bacterial metabolites in the colon. This study aimed to evaluate the combined effects of BARLEYmax and CPPs supplementation on fecal microbiota in vitro using pig feces for 48 h. The relative abundances of the family Clostridiaceae and the genus Clostridium and ammonia-nitrogen production were decreased by both BARLEYmax and CPP supplementation, and there was a positive correlation between their abundances and the ammonia-nitrogen concentration. Although acetate and n-butyrate production was decreased by CPP supplementation, their concentrations were maintained at a higher level in the BARLEYmax + CPP group than in the cellulose (control) and cellulose + CPP groups. Therefore, this study demonstrated that a combination of BARLEYmax and CPPs may be beneficial in maintaining higher short-chain fatty acid production and the elimination of potentially harmful factors. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10068-021-00959-z.

Deciphering the colonic fermentation characteristics of agavin and digestion-resistant maltodextrin in a simulated batch fermentation system.

Gut microbial fermentation of soluble dietary fibers promotes general and substrate-specific health benefits. In this study, the fermentation characteristics of two soluble branched-dietary fibers, namely, agavin (a type of agave fructans) and digestion-resistant maltodextrin (RD) were investigated against cellulose, using a simulated colonic fermenter apparatus employing a mixed culture of swine fecal bacteria. After 48 h of complete fermentation period, the microbial composition was different among all groups, where Bifidobacterium spp. and Lactobacillus spp. dominated the agavin treatment, while the members of the families Lachnospiraceae and Prevotellaceae dominated the RD treatment. Agavin treatment exhibited a clearly segregated two-phased prolonged fermentation trend compared to RD treatment as manifested by the fermentation rates. Further, the highest short-chain fatty acids production even at the end of the fermentation cycle, acidic pH, and the negligible concentration of ammonia accumulation demonstrated favorable fermentation attributes of agavin compared to RD. Therefore, agavin might be an effective and desirable substrate for the colonic microbiota than RD with reference to the expressed microbial taxa and fermentation attributes. This study revealed a notable significance of the structural differences of fermentable fibers on the subsequent fermentation characteristics.

Gene Fusions Create Partner and Collateral Dependencies Essential to Cancer Cell Survival.

Gene fusions frequently result from rearrangements in cancer genomes. In many instances, gene fusions play an important role in oncogenesis; in other instances, they are thought to be passenger events. Although regulatory element rearrangements and copy number alterations resulting from these structural variants are known to lead to transcriptional dysregulation across cancers, the extent to which these events result in functional dependencies with an impact on cancer cell survival is variable. Here we used CRISPR-Cas9 dependency screens to evaluate the fitness impact of 3,277 fusions across 645 cell lines from the Cancer Dependency Map. We found that 35% of cell lines harbored either a fusion partner dependency or a collateral dependency on a gene within the same topologically associating domain as a fusion partner. Fusion-associated dependencies revealed numerous novel oncogenic drivers and clinically translatable alterations. Broadly, fusions can result in partner and collateral dependencies that have biological and clinical relevance across cancer types. SIGNIFICANCE: This study provides insights into how fusions contribute to fitness in different cancer contexts beyond partner-gene activation events, identifying partner and collateral dependencies that may have direct implications for clinical care.

Bile acids induced hepatic lipid accumulation in mice by inhibiting mRNA expression of patatin-like phospholipase domain containing 3 and microsomal triglyceride transfer protein.

Preliminary studies have shown that a lithogenic diet (LG), which contains cholesterol and cholic acid, induces gallstones and hepatic lipid accumulation (HLA), and reduction of blood triglyceride in mice. We hypothesized that an LG induces HLA by diminishing hepatic triglyceride excretion; however, there is no clear understanding of the mechanism of LG-induced HLA. This study aimed to investigate transcript expression related to the synthesis, expenditure, and efflux of hepatic triglyceride, in mice fed an LG for 4 weeks. Results showed lower plasma concentrations of triglyceride in the LG group than in the control group, but no symptoms of hepatic injury were observed. Hepatic mRNA expressions of patatin-like phospholipase domain containing 3 (Pnpla3), microsomal triglyceride transfer protein (Mttp), and acyl-CoA oxidase 1 (Acox1) were also reduced in the LG group. Deoxycholic acid and lithocholic acid promoted intracellular lipid accumulation, reduced triglyceride concentration in media, and suppressed expression of PNPLA3 and MTTP in HepG2 human hepatoma cells. These findings suggest that deoxycholic acid and lithocholic acid promote HLA by inhibiting the expression of PNPLA3, ACOX1, and MTTP that are involved in lipid metabolism.

Dry-aged beef manufactured in Japan: Microbiota identification and their effects on product characteristics.

We aimed to determine the mold, yeast, and bacterial distributions in dry-aged beef (DAB) manufactured in Hokkaido, Japan, and to study their effects on meat quality compared to wet-aged beef (WAB). Two rump blocks from Holstein steer were dry- and wet-aged for 35 days at 2.9 °C and 90% RH. The psychrophilic molds Mucor flavus and Helicostylum pulchrum and other fungi (Penicillium sp. and Debaryomyces sp.) appeared on the crust of DAB, while lactic acid bacteria and coliforms were suppressed in the inner part of the meat. The composition of C16:0, C18:0, and C18:1 fatty acids did not differ between DAB and WAB, while more C17:0 fatty acids were detected in DAB. Dry aging suppressed acids and increased the production of various aroma compounds with mushroom-like, nutty, and other pleasant flavors. The meat quality and free amino acid (FAA) contents of DAB and WAB did not differ significantly. In this study, we identified major molds on DAB, which might contribute to an increase in aroma. Keywords: dry-aged beef; Mucor flavus; Helicostylum pulchrum; psychrophilic mold; meat quality; volatile aroma compounds.

p53 is a central regulator driving neurodegeneration caused by C9orf72 poly(PR).

The most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is a GGGGCC repeat expansion in the C9orf72 gene. We developed a platform to interrogate the chromatin accessibility landscape and transcriptional program within neurons during degeneration. We provide evidence that neurons expressing the dipeptide repeat protein poly(proline-arginine), translated from the C9orf72 repeat expansion, activate a highly specific transcriptional program, exemplified by a single transcription factor, p53. Ablating p53 in mice completely rescued neurons from degeneration and markedly increased survival in a C9orf72 mouse model. p53 reduction also rescued axonal degeneration caused by poly(glycine-arginine), increased survival of C9orf72 ALS/FTD-patient-induced pluripotent stem cell (iPSC)-derived motor neurons, and mitigated neurodegeneration in a C9orf72 fly model. We show that p53 activates a downstream transcriptional program, including Puma, which drives neurodegeneration. These data demonstrate a neurodegenerative mechanism dynamically regulated through transcription-factor-binding events and provide a framework to apply chromatin accessibility and transcription program profiles to neurodegeneration.

Effect of polyphenols isolated from purple sweet potato (Ipomoea batatas cv. Ayamurasaki) on the microbiota and the biomarker of colonic fermentation in rats fed with cellulose or inulin.

A polyphenol-rich diet has been associated with various health benefits. This study assessed the effects of polyphenol/anthocyanin isolated from a purple sweet potato (Ipomoea batatas cv. Ayamurasaki) on colonic fermentation in cellulose- or inulin-fed rats. Male Fischer-344 rats were assigned to one of these experimental diets: 5% cellulose (CEL), 5% CEL + 1% purple sweet potato polyphenol extract (CELP), 5% inulin (INU), and 5% INU + 1% purple sweet potato polyphenol extract (INUP) in each diet. The purple sweet potato polyphenol extract (PSPP) increased the relative abundance of Dorea and reduced the relative abundances of Oscillospira and Bacteroides in cellulose- or inulin-fed rats, respectively. Besides, PSPP reduced the caecal iso-butyrate and pH in the cellulose-fed rats. Further, PSPP triggered an increase in the caecal mucin level when combined with cellulose and increased the caecal IgA level while reducing the indole production in both the cellulose- or inulin-fed rats. Finally, PSPP may have different effects on the intestinal fermentation properties depending on the fermentability of dietary fiber associated with it. Therefore, this study demonstrated that dietary inclusion of polyphenol/anthocyanin from purple sweet potato might confer positive health attributes to the host gut.

Frozen Autoclaved Sorghum Enhanced Colonic Fermentation and Lower Visceral Fat Accumulation in Rats.

As raw sorghum is not able to influence considerable colonic fermentation despite its higher resistant starch (RS) content, our study aimed to investigate the effects of frozen autoclaved sorghum on colonic fermentation. Fischer 344 rats were fed frozen cooked refined (S-Rf) and whole (S-Wh) sorghum diets and were compared against α-corn starch (CON) and high amylose starch (HAS) fed rats for zoometric parameters, cecal biochemical and microbiological parameters. Sorghum fed rats exhibited significantly lower feed intake and visceral adipose tissue mass compared to CON. Bacterial alpha diversity was significantly higher in the sorghum fed rats compared to HAS and the two sorghum fed groups clustered together, separately from HAS and CON in the beta diversity plot. Serum non-High Density Lipoprotein cholesterol and total cholesterol in S-Rf group were significantly lower compared to CON, while total fecal bile excretion was also significantly higher in the two sorghum fed groups. Lower visceral adiposity was correlated with lower feed intake, RS content ingested and cecal short chain fatty acid (SCFA) contents. Thus, higher RS inflow to the colon via frozen autoclaved sorghum might have influenced colonic fermentation of RS and the resultant SCFA might have influenced lower adiposity as manifested by the lower body weight gain.

Combined Proteomic and Genetic Interaction Mapping Reveals New RAS Effector Pathways and Susceptibilities.

Activating mutations in RAS GTPases drive many cancers, but limited understanding of less-studied RAS interactors, and of the specific roles of different RAS interactor paralogs, continues to limit target discovery. We developed a multistage discovery and screening process to systematically identify genes conferring RAS-related susceptibilities in lung adenocarcinoma. Using affinity purification mass spectrometry, we generated a protein-protein interaction map of RAS interactors and pathway components containing hundreds of interactions. From this network, we constructed a CRISPR dual knockout library targeting 119 RAS-related genes that we screened for KRAS-dependent genetic interactions (GI). This approach identified new RAS effectors, including the adhesion controller RADIL and the endocytosis regulator RIN1, and >250 synthetic lethal GIs, including a potent KRAS-dependent interaction between RAP1GDS1 and RHOA. Many GIs link specific paralogs within and between gene families. These findings illustrate the power of multiomic approaches to uncover synthetic lethal combinations specific for hitherto untreatable cancer genotypes. SIGNIFICANCE: We establish a deep network of protein-protein and genetic interactions in the RAS pathway. Many interactions validated here demonstrate important specificities and redundancies among paralogous RAS regulators and effectors. By comparing synthetic lethal interactions across KRAS-dependent and KRAS-independent cell lines, we identify several new combination therapy targets for RAS-driven cancers.This article is highlighted in the In This Issue feature, p. 1775.