Dicarboxylic fatty acids are generated in the liver and kidney in a minor pathway called fatty acid ω-oxidation. The effects of consuming dicarboxylic fatty acids as an alternative source of dietary fat have not been explored. Here, we fed dodecanedioic acid, a 12-carbon dicarboxylic (DC12), to mice at 20% of daily caloric intake for 9 weeks. DC12 increased metabolic rate, reduced body fat, reduced liver fat, and improved glucose tolerance. We observed DC12-specific breakdown products in liver, kidney, muscle, heart, and brain, indicating that oral DC12 escaped first-pass liver metabolism and was utilized by many tissues. In tissues expressing the “a” isoform of acyl-CoA oxidase-1 (ACOX1), a key peroxisomal fatty acid oxidation enzyme, DC12 was chain shortened to the TCA cycle intermediate succinyl-CoA. In tissues with low peroxisomal fatty acid oxidation capacity, DC12 was oxidized by mitochondria. In vitro, DC12 was catabolized even by adipose tissue and was not stored intracellularly. We conclude that DC12 and other dicarboxylic acids may be useful for combatting obesity and for treating metabolic disorders.
Eric S. Goetzman, Bob B. Zhang, Yuxun Zhang, Sivakama S. Bharathi, Joanna Bons, Jacob Rose, Samah Shah, Keaton J. Solo, Alexandra V. Schmidt, Adam C. Richert, Steven J. Mullett, Stacy L. Gelhaus, Krithika S. Rao, Sruti S. Shiva, Katherine E. Pfister, Anne Silva Barbosa, Sunder Sims-Lucas, Steven F. Dobrowolski, Birgit Schilling
We describe a previously unappreciated role for Bruton’s tyrosine kinase (BTK) in fungal immune surveillance against aspergillosis, an unforeseen complication of BTK inhibitors (BTKi) used for treating B cell lymphoid malignancies. We studied BTK-dependent fungal responses in neutrophils from diverse populations, including healthy donors, patients who were treated with BTKi, and X-linked agammaglobulinemia patients. Upon fungal exposure, BTK was activated in human neutrophils in a TLR2-, Dectin-1-, and FcγR-dependent manner, triggering the oxidative burst. BTK inhibition selectively impeded neutrophil-mediated damage to Aspergillus hyphae, primary granule release, and the fungus-induced oxidative burst by abrogating NADPH oxidase subunit p40phox and GTPase RAC2 activation. Moreover, neutrophil-specific Btk deletion in mice enhanced aspergillosis susceptibility by impairing neutrophil function, not recruitment or lifespan. Conversely, GM-CSF partially mitigated these deficits by enhancing p47phox activation. Our findings underline the crucial role of BTK signaling in neutrophils for antifungal immunity and provide a rationale for GM-CSF use to offset these deficits in patients who are susceptible.
Jigar V. Desai, Marissa A. Zarakas, Andrew L. Wishart, Mark Roschewski, Mariano A. Aufiero, Agnes Donkò, Gustaf Wigerblad, Neta Shlezinger, Markus Plate, Matthew R. James, Jean K. Lim, Gulbu Uzel, Jenna R.E. Bergerson, Ivan Fuss, Robert A. Cramer, Luis M. Franco, Emily S. Clark, Wasif N. Khan, Daisuke Yamanaka, Georgios Chamilos, Jamel El-Benna, Mariana J. Kaplan, Louis M. Staudt, Thomas L. Leto, Steven M. Holland, Wyndham H. Wilson, Tobias M. Hohl, Michail S. Lionakis
Splicing factor mutations are common in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), but how they alter cellular functions is unclear. We show that the pathogenic SRSF2P95H/+ mutation disrupts the splicing of mitochondrial mRNAs, impairs mitochondrial complex I function, and robustly increases mitophagy. We also identified a mitochondrial surveillance mechanism by which mitochondrial dysfunction modifies splicing of the mitophagy activator PINK1 to remove a poison intron, increasing the stability and abundance of PINK1 mRNA and protein. SRSF2P95H-induced mitochondrial dysfunction increased PINK1 expression through this mechanism, which is essential for survival of SRSF2P95H/+ cells. Inhibition of splicing with a glycogen synthase kinase 3 inhibitor promoted retention of the poison intron, impairing mitophagy and activating apoptosis in SRSF2P95H/+ cells. These data reveal a homeostatic mechanism for sensing mitochondrial stress through PINK1 splicing and identify increased mitophagy as a disease marker and a therapeutic vulnerability in SRSF2P95H mutant MDS and AML.
Xiaolei Liu, Sudhish A. Devadiga, Robert F. Stanley, Ryan M. Morrow, Kevin A. Janssen, Mathieu Quesnel-Vallières, Oz Pomp, Adam A. Moverley, Chenchen Li, Nicolas Skuli, Martin Carroll, Jian Huang, Douglas C. Wallace, Kristen W. Lynch, Omar Abdel-Wahab, Peter S. Klein
Spinal muscular atrophy (SMA) is typically characterized as a motor neuron disease, but extraneuronal phenotypes are present in almost every organ in severely affected patients and animal models. Extraneuronal phenotypes were previously underappreciated, as patients with severe SMA phenotypes usually died in infancy; however, with current treatments for motor neurons increasing patient lifespan, impaired function of peripheral organs may develop into significant future comorbidities and lead to new treatment-modified phenotypes. Fatty liver is seen in SMA animal models, but generalizability to patients and whether this is due to hepatocyte-intrinsic survival motor neuron (SMN) protein deficiency and/or subsequent to skeletal muscle denervation is unknown. If liver pathology in SMA is SMN dependent and hepatocyte intrinsic, this suggests SMN-repleting therapies must target extraneuronal tissues and motor neurons for optimal patient outcome. Here, we showed that fatty liver is present in SMA patients and that SMA patient–specific induced pluripotent stem cell–derived hepatocyte-like cells were susceptible to steatosis. Using proteomics, functional studies, and CRISPR/Cas9 gene editing, we confirmed that fatty liver in SMA is a primary SMN-dependent hepatocyte-intrinsic liver defect associated with mitochondrial and other hepatic metabolism implications. These pathologies require monitoring and indicate the need for systematic clinical surveillance and additional and/or combinatorial therapies to ensure continued SMA patient health.
Damien Meng-Kiat Leow, Yang Kai Ng, Loo Chien Wang, Hiromi W.L. Koh, Tianyun Zhao, Zi Jian Khong, Tommaso Tabaglio, Gunaseelan Narayanan, Richard M. Giadone, Radoslaw M. Sobota, Shi-Yan Ng, Adrian Kee Keong Teo, Simon H. Parson, Lee L. Rubin, Wei-Yi Ong, Basil T. Darras, Crystal J.J. Yeo
Pancreatic β cell dysfunction is a key feature of type 2 diabetes, and novel regulators of insulin secretion are desirable. Here, we report that succinate receptor 1 (SUCNR1) is expressed in β cells and is upregulated in hyperglycemic states in mice and humans. We found that succinate acted as a hormone-like metabolite and stimulated insulin secretion via a SUCNR1-Gq-PKC–dependent mechanism in human β cells. Mice with β cell–specific Sucnr1 deficiency exhibited impaired glucose tolerance and insulin secretion on a high-fat diet, indicating that SUCNR1 is essential for preserving insulin secretion in diet-induced insulin resistance. Patients with impaired glucose tolerance showed an enhanced nutrition-related succinate response, which correlates with the potentiation of insulin secretion during intravenous glucose administration. These data demonstrate that the succinate/SUCNR1 axis is activated by high glucose and identify a GPCR-mediated amplifying pathway for insulin secretion relevant to the hyperinsulinemia of prediabetic states.
Joan Sabadell-Basallote, Brenno Astiarraga, Carlos Castaño, Miriam Ejarque, Maria Repollés-de-Dalmau, Ivan Quesada, Jordi Blanco, Catalina Núñez-Roa, M-Mar Rodríguez-Peña, Laia Martínez, Dario F. De Jesus, Laura Marroquí, Ramon Bosch, Eduard Montanya, Francesc X. Sureda, Andrea Tura, Andrea Mari, Rohit N. Kulkarni, Joan Vendrell, Sonia Fernández-Veledo
Cells expressing features of senescence, including upregulation of p21 and p16, appear transiently following tissue injury, yet the properties of these cells or how they contrast with age-induced senescent cells remains unclear. Here, we used skeletal injury as a model and identified the rapid appearance following fracture of p21+ cells expressing senescence markers, mainly as osteochondroprogenitors (OCHs) and neutrophils. Targeted genetic clearance of p21+ cells suppressed senescence-associated signatures within the fracture callus and accelerated fracture healing. By contrast, p21+ cell clearance did not alter bone loss due to aging; conversely, p16+ cell clearance, known to alleviate skeletal aging, did not affect fracture healing. Following fracture, p21+ neutrophils were enriched in signaling pathways known to induce paracrine stromal senescence, while p21+ OCHs were highly enriched in senescence-associated secretory phenotype factors known to impair bone formation. Further analysis revealed an injury-specific stem cell–like OCH subset that was p21+ and highly inflammatory, with a similar inflammatory mesenchymal population (fibro-adipogenic progenitors) evident following muscle injury. Thus, intercommunicating senescent-like neutrophils and mesenchymal progenitor cells were key regulators of tissue repair in bone and potentially across tissues. Moreover, our findings established contextual roles of p21+ versus p16+ senescent/senescent-like cells that may be leveraged for therapeutic opportunities.
Dominik Saul, Madison L. Doolittle, Jennifer L. Rowsey, Mitchell N. Froemming, Robyn L. Kosinsky, Stephanie J. Vos, Ming Ruan, Nathan K. LeBrasseur, Abhishek Chandra, Robert J. Pignolo, João F. Passos, Joshua N. Farr, David G. Monroe, Sundeep Khosla
Cancer cells exhibit heightened secretory states that drive tumor progression. Here, we identified a chromosome 3q amplicon that serves as a platform for secretory regulation in cancer. The 3q amplicon encodes multiple Golgi-resident proteins, including the scaffold Golgi integral membrane protein 4 (GOLIM4) and the ion channel ATPase secretory pathway Ca2+ transporting 1 (ATP2C1). We show that GOLIM4 recruited ATP2C1 and Golgi phosphoprotein 3 (GOLPH3) to coordinate Ca2+-dependent cargo loading, Golgi membrane bending, and vesicle scission. GOLIM4 depletion disrupted the protein complex, resulting in a secretory blockade that inhibited the progression of 3q-amplified malignancies. In addition to its role as a scaffold, GOLIM4 maintained intracellular manganese (Mn) homeostasis by binding excess Mn in the Golgi lumen, which initiated the routing of Mn-bound GOLIM4 to lysosomes for degradation. We show that Mn treatment inhibited the progression of multiple types of 3q-amplified malignancies by degrading GOLIM4, resulting in a secretory blockade that interrupted prosurvival autocrine loops and attenuated prometastatic processes in the tumor microenvironment. As it potentially underlies the selective activity of Mn against 3q-amplified malignancies, ATP2C1 coamplification increased Mn influx into the Golgi lumen, resulting in a more rapid degradation of GOLIM4. These findings show that functional cooperativity between coamplified genes underlies heightened secretion and a targetable secretory addiction in 3q-amplified malignancies.
Xiaochao Tan, Shike Wang, Guan-Yu Xiao, Chao Wu, Xin Liu, Biyao Zhou, Yu Jiang, Dzifa Y. Duose, Yuanxin Xi, Jing Wang, Kunika Gupta, Apar Pataer, Jack A. Roth, Michael P. Kim, Fengju Chen, Chad J. Creighton, William K. Russell, Jonathan M. Kurie
Satellite cells, the stem cells of skeletal muscle tissue, hold a remarkable regeneration capacity and therapeutic potential in regenerative medicine. However, low satellite cell yield from autologous or donor-derived muscles hinders the adoption of satellite cell transplantation for the treatment of muscle diseases, including Duchenne muscular dystrophy (DMD). To address this limitation, here we investigated whether satellite cells can be derived in allogeneic or xenogeneic animal hosts. First, injection of CRISPR/Cas9-corrected Dmdmdx mouse induced pluripotent stem cells (iPSCs) into mouse blastocysts carrying an ablation system of host satellite cells gave rise to intraspecies chimeras exclusively carrying iPSC-derived satellite cells. Furthermore, injection of genetically corrected DMD iPSCs into rat blastocysts resulted in the formation of interspecies rat-mouse chimeras harboring mouse satellite cells. Notably, iPSC-derived satellite cells or derivative myoblasts produced in intraspecies or interspecies chimeras restored dystrophin expression in DMD mice following intramuscular transplantation and contributed to the satellite cell pool. Collectively, this study demonstrates the feasibility of producing therapeutically competent stem cells across divergent animal species, raising the possibility of generating human muscle stem cells in large animals for regenerative medicine purposes.
Ajda Lenardič, Seraina A. Domenig, Joel Zvick, Nicola Bundschuh, Monika Tarnowska-Sengül, Regula Furrer, Falko Noé, Christine L. Trautmann, Adhideb Ghosh, Giada Bacchin, Pjeter Gjonlleshaj, Xhem Qabrati, Evi Masschelein, Katrien De Bock, Christoph Handschin, Ori Bar-Nur
Glucose plays a key role in shaping pancreatic β cell function. Thus, deciphering the mechanisms by which this nutrient stimulates β cells holds therapeutic promise for combating β cell failure in type 2 diabetes (T2D). β Cells respond to hyperglycemia in part by rewiring their mRNA metabolism, yet the mechanisms governing these changes remain poorly understood. Here, we identify a requirement for the RNA-binding protein PCBP2 in maintaining β cell function basally and during sustained hyperglycemic challenge. PCBP2 was induced in primary mouse islets incubated with elevated glucose and was required to adapt insulin secretion. Transcriptomic analysis of primary Pcbp2-deficient β cells revealed impacts on basal and glucose-regulated mRNAs encoding core components of the insulin secretory pathway. Accordingly, Pcbp2-deficient β cells exhibited defects in calcium flux, insulin granule ultrastructure and exocytosis, and the amplification pathway of insulin secretion. Further, PCBP2 was induced by glucose in primary human islets, was downregulated in islets from T2D donors, and impacted genes commonly altered in islets from donors with T2D and linked to single-nucleotide polymorphisms associated with T2D. Thus, these findings establish a paradigm for PCBP2 in governing basal and glucose-adaptive gene programs critical for shaping the functional state of β cells.
Matthew W. Haemmerle, Andrea V. Scota, Mina Khosravifar, Matthew J. Varney, Sabyasachi Sen, Austin L. Good, Xiaodun Yang, Kristen L. Wells, Lori Sussel, Andrea V. Rozo, Nicolai M. Doliba, Louis R. Ghanem, Doris A. Stoffers
Clear cell renal cell carcinoma (ccRCC) is an aggressive cancer driven by VHL loss and aberrant HIF-2α signaling. Identifying means to regulate HIF-2α thus has potential therapeutic benefit. Acetyl-CoA synthetase 2 (ACSS2) converts acetate to acetyl-CoA and is associated with poor patient prognosis in ccRCC. Here we tested the effects of ACSS2 on HIF-2α and cancer cell metabolism and growth in ccRCC models and clinical samples. ACSS2 inhibition reduced HIF-2α levels and suppressed ccRCC cell line growth in vitro, in vivo, and in cultures of primary ccRCC patient tumors. This treatment reduced glycolytic signaling, cholesterol metabolism, and mitochondrial integrity, all of which are consistent with loss of HIF-2α. Mechanistically, ACSS2 inhibition decreased chromatin accessibility and HIF-2α expression and stability. While HIF-2α protein levels are widely regulated through pVHL-dependent proteolytic degradation, we identify a potential pVHL-independent pathway of degradation via the E3 ligase MUL1. We show that MUL1 can directly interact with HIF-2α and that overexpression of MUL1 decreased HIF-2α levels in a manner partially dependent on ACSS2. These findings identify multiple mechanisms to regulate HIF-2α stability and ACSS2 inhibition as a strategy to complement HIF-2α–targeted therapies and deplete pathogenically stabilized HIF-2α.
Zachary A. Bacigalupa, Emily N. Arner, Logan M. Vlach, Melissa M. Wolf, Whitney A. Brown, Evan S. Krystofiak, Xiang Ye, Rachel A. Hongo, Madelyn Landis, Edith K. Amason, Kathryn E. Beckermann, W. Kimryn Rathmell, Jeffrey C. Rathmell
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