RESUMO
The glucocorticoid receptor (GR) is an important anti-cancer target in lymphoid cancers but has been understudied in solid tumors like lung cancer, although glucocorticoids are often given with chemotherapy regimens to mitigate side effects. Here, we identify a dexamethasone-GR mediated anti-cancer response in a subset of aggressive non-small cell lung cancers (NSCLCs) that harbor Serine/Threonine Kinase 11 (STK11/LKB1) mutations. High tumor expression of carbamoyl phosphate synthase 1 (CPS1) was strongly linked to the presence of LKB1 mutations, was the best predictor of NSCLC dexamethasone (DEX) sensitivity (p < 10-16) but was not mechanistically involved in DEX sensitivity. Subcutaneous, orthotopic and metastatic NSCLC xenografts, biomarker-selected, STK11/LKB1 mutant patient derived xenografts, and genetically engineered mouse models with KRAS/LKB1 mutant lung adenocarcinomas all showed marked in vivo anti-tumor responses with the glucocorticoid dexamethasone as a single agent or in combination with cisplatin. Mechanistically, GR activation triggers G1/S cell cycle arrest in LKB1 mutant NSCLCs by inducing the expression of the cyclin-dependent kinase inhibitor, CDKN1C/p57(Kip2). All findings were confirmed with functional genomic experiments including CRISPR knockouts and exogenous expression. Importantly, DEX-GR mediated cell cycle arrest did not interfere with NSCLC radiotherapy, or platinum response in vitro or with platinum response in vivo. While DEX induced LKB1 mutant NSCLCs in vitro exhibit markers of cellular senescence and demonstrate impaired migration, in vivo DEX treatment of a patient derived xenograft (PDX) STK11/LKB1 mutant model resulted in expression of apoptosis markers. These findings identify a previously unknown GR mediated therapeutic vulnerability in STK11/LKB1 mutant NSCLCs caused by induction of p57(Kip2) expression with both STK11 mutation and high expression of CPS1 as precision medicine biomarkers of this vulnerability.
RESUMO
Animals that consume fermenting fruit and nectar are at risk of exposure to ethanol and the detrimental effects of inebriation. In this report, we show that the hormone FGF21, which is strongly induced by ethanol in murine and human liver, stimulates arousal from intoxication without changing ethanol catabolism. Mice lacking FGF21 take longer than wild-type littermates to recover their righting reflex and balance following ethanol exposure. Conversely, pharmacologic FGF21 administration reduces the time needed for mice to recover from ethanol-induced unconsciousness and ataxia. FGF21 did not counteract sedation caused by ketamine, diazepam, or pentobarbital, indicating specificity for ethanol. FGF21 mediates its anti-intoxicant effects by directly activating noradrenergic neurons in the locus coeruleus region, which regulates arousal and alertness. These results suggest that this FGF21 liver-brain pathway evolved to protect against ethanol-induced intoxication and that it might be targeted pharmaceutically for treating acute alcohol poisoning.
Assuntos
Intoxicação Alcoólica , Humanos , Animais , Camundongos , Etanol/toxicidade , Fatores de Crescimento de Fibroblastos/metabolismo , Encéfalo/metabolismoRESUMO
Mechanisms governing morphogenesis and development of infectious third-stage larvae (L3i) of parasitic nematodes have been likened to those regulating dauer development in Caenorhabditis elegans. Dauer regulatory signal transduction comprises initial G protein-coupled receptor (GPCR) signaling in chemosensory neurons of the amphidial complex that regulates parallel insulin- and TGFß-like signaling in the tissues. Insulin- and TGFß-like signals converge to co-regulate steroid signaling through the nuclear receptor (NR) DAF-12. Discovery of the steroid ligands of DAF-12 opened a new avenue of small molecule physiology in C. elegans. These signaling pathways are conserved in parasitic nematodes and an increasing body of evidence supports their function in formation and developmental regulation of L3i during the infectious process in soil transmitted species. This review presents these lines of evidence for G protein-coupled receptor (GPCR), insulin- and TGFß-like signaling in brief and focuses primarily on signaling through parasite orthologs of DAF-12. We discuss in some depth the deployment of sensitive analytical techniques to identify Δ7-dafachronic acid as the natural ligand of DAF-12 homologs in Strongyloides stercoralis and Haemonchus contortus and of targeted mutagenesis by CRISPR/Cas9 to assign dauer-like regulatory function to the NR Ss-DAF-12, its coactivator Ss-DIP-1 and the key ligand biosynthetic enzyme Ss-CYP-22a9. Finally, we present published evidence of the potential of Ss-DAF-12 signaling as a chemotherapeutic target in human strongyloidiasis.
Assuntos
Proteínas de Caenorhabditis elegans , Insulinas , Parasitos , Strongyloides stercoralis , Estrongiloidíase , Animais , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Helminto/genética , Proteínas de Helminto/metabolismo , Humanos , Insulinas/metabolismo , Larva , Ligantes , Parasitos/metabolismo , Receptores Citoplasmáticos e Nucleares/genética , Receptores Citoplasmáticos e Nucleares/metabolismo , Esteroides/metabolismo , Strongyloides stercoralis/genética , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/metabolismoRESUMO
Schistosomes infect over 200 million of the world's poorest people, but unfortunately treatment relies on a single drug. Nuclear hormone receptors are ligand-activated transcription factors that regulate diverse processes in metazoans, yet few have been functionally characterized in schistosomes. During a systematic analysis of nuclear receptor function, we found that an FTZ-F1-like receptor was essential for parasite survival. Using a combination of transcriptional profiling and chromatin immunoprecipitation (ChIP), we discovered that the micro-exon gene meg-8.3 is a transcriptional target of SmFTZ-F1. We found that both Smftz-f1 and meg-8.3 are required for esophageal gland maintenance as well as integrity of the worm's head. Together, these studies define a new role for micro-exon gene function in the parasite and suggest that factors associated with the esophageal gland could represent viable therapeutic targets.
Assuntos
Esôfago/metabolismo , Regulação da Expressão Gênica/fisiologia , Proteínas de Helminto/metabolismo , Schistosoma mansoni/metabolismo , Fatores de Transcrição/metabolismo , AnimaisRESUMO
A prevalent feature of Strongyloides stercoralis is a life-long and potentially lethal infection that is due to the nematode parasite's ability to autoinfect and, thereby, self-replicate within its host. Here, we investigated the role of the parasite's nuclear receptor, Ss-DAF-12, in governing infection. We identified Δ7-DA as the endogenous Ss-DAF-12 ligand and elucidated the hormone's biosynthetic pathway. Genetic loss of function of the ligand's rate-limiting enzyme demonstrated that Δ7-DA synthesis is necessary for parasite reproduction, whereas its absence is required for the development of infectious larvae. Availability of the ligand permits Ss-DAF-12 to function as an on/off switch governing autoinfection, making it vulnerable to therapeutic intervention. In a preclinical model of hyperinfection, pharmacologic activation of DAF-12 suppressed autoinfection and markedly reduced lethality. Moreover, when Δ7-DA was administered with ivermectin, the current but limited drug of choice for treating strongyloidiasis, the combinatorial effects of the two drugs resulted in a near cure of the disease.
Assuntos
Anti-Helmínticos/farmacologia , Ivermectina/farmacocinética , Receptores Citoplasmáticos e Nucleares/agonistas , Strongyloides stercoralis/efeitos dos fármacos , Estrongiloidíase/parasitologia , Animais , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/química , Cães , Gerbillinae , Ligantes , Masculino , Estrongiloidíase/tratamento farmacológicoRESUMO
The contribution of adipose-derived FGF21 to energy homeostasis is unclear. Here we show that browning of inguinal white adipose tissue (iWAT) by ß-adrenergic agonists requires autocrine FGF21 signaling. Adipose-specific deletion of the FGF21 co-receptor ß-Klotho renders mice unresponsive to ß-adrenergic stimulation. In contrast, mice with liver-specific ablation of FGF21, which eliminates circulating FGF21, remain sensitive to ß-adrenergic browning of iWAT. Concordantly, transgenic overexpression of FGF21 in adipocytes promotes browning in a ß-Klotho-dependent manner without increasing circulating FGF21. Mechanistically, we show that ß-adrenergic stimulation of thermogenic gene expression requires FGF21 in adipocytes to promote phosphorylation of phospholipase C-γ and mobilization of intracellular calcium. Moreover, we find that the ß-adrenergic-dependent increase in circulating FGF21 occurs through an indirect mechanism in which fatty acids released by adipocyte lipolysis subsequently activate hepatic PPARα to increase FGF21 expression. These studies identify FGF21 as a cell-autonomous autocrine regulator of adipose tissue function.
Assuntos
Adipócitos/metabolismo , Comunicação Autócrina , Fatores de Crescimento de Fibroblastos/metabolismo , Regulação da Expressão Gênica , Termogênese/genética , Células 3T3-L1 , Tecido Adiposo Marrom/metabolismo , Tecido Adiposo Branco/metabolismo , Agonistas Adrenérgicos beta , Animais , Comunicação Autócrina/genética , Fatores de Crescimento de Fibroblastos/sangue , Fatores de Crescimento de Fibroblastos/genética , Lipólise , Fígado/metabolismo , Camundongos , Especificidade de Órgãos , Ligação Proteica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores Adrenérgicos beta 3/metabolismo , Receptores de Fatores de Crescimento de Fibroblastos/metabolismoRESUMO
DAF-12 is nematode-specific nuclear receptor that has been proposed to govern development of the infectious stage of parasitic species, including Strongyloides stercoralis Here, we identified a parasite-specific coactivator, called DAF-12 interacting protein-1 (DIP-1), that is required for DAF-12 ligand-dependent transcriptional activity. DIP-1 is found only in Strongyloides spp. and selectively interacts with DAF-12 through an atypical receptor binding motif. Using CRISPR/Cas9-directed mutagenesis, we demonstrate that DAF-12 is required for the requisite developmental arrest and the ligand-dependent reactivation of infectious S. stercoralis infective third-stage larvae, and that these effects require the DIP-1 coactivator. These studies reveal the existence of a distinct nuclear receptor/coactivator signaling pathway that governs parasite development.
Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/crescimento & desenvolvimento , Regulação da Expressão Gênica no Desenvolvimento , Larva/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Strongyloides stercoralis/parasitologia , Fatores de Transcrição/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , Sistemas CRISPR-Cas , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Larva/genética , Larva/crescimento & desenvolvimento , Receptores Citoplasmáticos e Nucleares/genética , Strongyloides stercoralis/genética , Fatores de Transcrição/genéticaRESUMO
BACKGROUND: While immune responses to the murine hookworm Nippostrongylus brasiliensis have been investigated, signaling pathways regulating development of infectious larvae (iL3) are not well understood. We hypothesized that N. brasiliensis would use pathways similar to those controlling dauer development in the free-living nematode Caenorhabditis elegans, which is formally known as the "dauer hypothesis." METHODS: To investigate whether dafachronic acid activates the N. brasiliensis DAF-12 homolog, we utilized an in vitro reporter assay. We then utilized RNA-Seq and subsequent bioinformatic analyses to identify N. brasiliensis dauer pathway homologs and examine regulation of these genes during iL3 activation. RESULTS: In this study, we demonstrated that dafachronic acid activates the N. brasiliensis DAF-12 homolog. We then identified N. brasiliensis homologs for members in each of the four canonical dauer pathways and examined their regulation during iL3 activation by either temperature or dafachronic acid. Similar to C. elegans, we found that transcripts encoding antagonistic insulin-like peptides were significantly downregulated during iL3 activation, and that a transcript encoding a phylogenetic homolog of DAF-9 increased during iL3 activation, suggesting that both increased insulin-like and DAF-12 nuclear hormone receptor signaling accompanies iL3 activation. In contrast to C. elegans, we observed a significant decrease in transcripts encoding the dauer transforming growth factor beta ligand DAF-7 during iL3 activation, suggesting a different role for this pathway in parasitic nematode development. CONCLUSIONS: Our data suggest that canonical dauer pathways indeed regulate iL3 activation in the hookworm N. brasiliensis and that DAF-12 may be a therapeutic target in hookworm infections.
Assuntos
Colestenos/farmacologia , Nippostrongylus/efeitos dos fármacos , Nippostrongylus/genética , Transdução de Sinais/efeitos dos fármacos , Temperatura , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Proteínas de Caenorhabditis elegans/genética , Biologia Computacional , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Helminto/genética , Larva/efeitos dos fármacos , Larva/genética , Larva/crescimento & desenvolvimento , Filogenia , RNA-SeqRESUMO
The exocrine pancreas expresses the highest concentrations of fibroblast growth factor 21 (FGF21) in the body, where it maintains acinar cell proteostasis. Here, we showed in both mice and humans that acute and chronic pancreatitis is associated with a loss of FGF21 expression due to activation of the integrated stress response (ISR) pathway. Mechanistically, we found that activation of the ISR in cultured acinar cells and mouse pancreata induced the expression of ATF3, a transcriptional repressor that directly bound to specific sites on the Fgf21 promoter and resulted in loss of FGF21 expression. These ATF3 binding sites are conserved in the human FGF21 promoter. Consistent with the mouse studies, we also observed the reciprocal expression of ATF3 and FGF21 in the pancreata of human patients with pancreatitis. Using three different mouse models of pancreatitis, we showed that pharmacologic replacement of FGF21 mitigated the ISR and resolved pancreatitis. Likewise, inhibition of the ISR with an inhibitor of the PKR-like endoplasmic reticulum kinase (PERK) also restored FGF21 expression and alleviated pancreatitis. These findings highlight the importance of FGF21 in preserving exocrine pancreas function and suggest its therapeutic use for prevention and treatment of pancreatitis.
Assuntos
Fatores de Crescimento de Fibroblastos/deficiência , Pancreatite/terapia , Células Acinares/metabolismo , Células Acinares/patologia , Fator 3 Ativador da Transcrição/metabolismo , Fator 4 Ativador da Transcrição , Animais , Sequência de Bases , Regulação para Baixo , Fatores de Crescimento de Fibroblastos/administração & dosagem , Fatores de Crescimento de Fibroblastos/genética , Fatores de Crescimento de Fibroblastos/metabolismo , Glucuronidase/metabolismo , Humanos , Proteínas Klotho , Camundongos Knockout , Pâncreas Exócrino/patologia , Pancreatite/genética , Pancreatite/patologia , Regiões Promotoras Genéticas/genética , Ligação Proteica , eIF-2 Quinase/antagonistas & inibidores , eIF-2 Quinase/metabolismoRESUMO
The orphan nuclear receptor SHP (small heterodimer partner) is a well-known transcriptional corepressor of bile acid and lipid metabolism in the liver; however, its function in other tissues is poorly understood. Here, we report an unexpected role for SHP in the exocrine pancreas as a modulator of the endoplasmic reticulum (ER) stress response. SHP expression is induced in acinar cells in response to ER stress and regulates the protein stability of the spliced form of X-box-binding protein 1 (XBP1s), a key mediator of ER stress response. Loss of SHP reduces XBP1s protein level and transcriptional activity, which in turn attenuates the ER stress response during the fasting-feeding cycle. Consequently, SHP-deficient mice also are more susceptible to cerulein-induced pancreatitis. Mechanistically, we show that SHP physically interacts with the transactivation domain of XBP1s, thereby inhibiting the polyubiquitination and degradation of XBP1s by the Cullin3-SPOP (speckle-type POZ protein) E3 ligase complex. Together, our data implicate SHP in governing ER homeostasis and identify a novel posttranslational regulatory mechanism for the key ER stress response effector XBP1.
Assuntos
Estresse do Retículo Endoplasmático/genética , Proteólise , Receptores Citoplasmáticos e Nucleares/metabolismo , Proteína 1 de Ligação a X-Box/metabolismo , Células Acinares/metabolismo , Animais , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/genética , Células HEK293 , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Pâncreas Exócrino/metabolismo , Pancreatite/genética , Processamento de Proteína , Estabilidade Proteica , Receptores Citoplasmáticos e Nucleares/deficiência , Receptores Citoplasmáticos e Nucleares/genética , Ubiquitinação/genéticaRESUMO
It has been more than a dozen years since FGF21 burst on the metabolism field in a paper showing that its pharmacologic administration caused weight loss and improved insulin sensitivity and lipoprotein profiles in obese rodents. Since then, FGF21 analogs have advanced all the way to clinical trials, and much progress has been made in understanding FGF21's pharmacology and physiology. In this Perspective, we highlight some of the interesting themes that have emerged from this first dozen years of FGF21 research, including its roles in autocrine/paracrine and endocrine responses to metabolic stress.
Assuntos
Fatores de Crescimento de Fibroblastos , Obesidade , Redução de Peso/efeitos dos fármacos , Animais , Fatores de Crescimento de Fibroblastos/farmacologia , Fatores de Crescimento de Fibroblastos/fisiologia , Humanos , Resistência à Insulina , Camundongos , Obesidade/tratamento farmacológico , Obesidade/metabolismo , RatosRESUMO
The nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) is a master regulator of adipocyte differentiation and is the target for the insulin-sensitizing thiazolidinedione (TZD) drugs used to treat type 2 diabetes. In cell-based in vitro studies, the transcriptional activity of PPARγ is inhibited by covalent attachment of small ubiquitin-related modifier (SUMOylation) at K107 in its N terminus. However, whether this posttranslational modification is relevant in vivo remains unclear. Here, using mice homozygous for a mutation (K107R) that prevents SUMOylation at this position, we demonstrate that PPARγ is SUMOylated at K107 in white adipose tissue. We further show that in the context of diet-induced obesity PPARγ-K107R-mutant mice have enhanced insulin sensitivity without the corresponding increase in adiposity that typically accompanies PPARγ activation by TZDs. Accordingly, the PPARγ-K107R mutation was weaker than TZD treatment in stimulating adipocyte differentiation in vitro. Moreover, we found that both the basal and TZD-dependent transcriptomes of inguinal and epididymal white adipose tissue depots were markedly altered in the K107R-mutant mice. We conclude that PPARγ SUMOylation at K107 is physiologically relevant and may serve as a pharmacologic target for uncoupling PPARγ's beneficial insulin-sensitizing effect from its adverse effect of weight gain.
Assuntos
Adiposidade , Insulina/metabolismo , Lisina/metabolismo , Obesidade/metabolismo , PPAR gama/metabolismo , Tecido Adiposo/metabolismo , Motivos de Aminoácidos , Animais , Feminino , Humanos , Lisina/genética , Masculino , Camundongos , Mutação de Sentido Incorreto , Obesidade/genética , Obesidade/fisiopatologia , PPAR gama/química , PPAR gama/genética , Proteína SUMO-1 , SumoilaçãoRESUMO
Alcohol and ketogenic diets increase water consumption. Here, we show that the hormone FGF21 is required for this drinking response in mice. Circulating levels of FGF21 are increased by alcohol consumption in humans and by both alcohol and ketogenic diets in mice. Pharmacologic administration of FGF21 stimulates water drinking behavior in mice within 2 hr. Concordantly, mice lacking FGF21 fail to increase water intake in response to either alcohol or a ketogenic diet. The effect of FGF21 on drinking is mediated in part by SIM1-positive neurons of the hypothalamus and is inhibited by ß-adrenergic receptor antagonists. Given that FGF21 also is known to suppress alcohol intake in favor of pure water, this work identifies FGF21 as a fundamental neurotropic hormone that governs water balance in response to specific nutrient stresses that can cause dehydration.
Assuntos
Consumo de Bebidas Alcoólicas/efeitos adversos , Dieta Cetogênica/efeitos adversos , Ingestão de Líquidos/fisiologia , Fatores de Crescimento de Fibroblastos/farmacologia , Fatores de Crescimento de Fibroblastos/fisiologia , Antagonistas Adrenérgicos beta/administração & dosagem , Adulto , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Ingestão de Líquidos/efeitos dos fármacos , Feminino , Fatores de Crescimento de Fibroblastos/administração & dosagem , Fatores de Crescimento de Fibroblastos/genética , Voluntários Saudáveis , Humanos , Hipotálamo/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Repressoras/metabolismo , Transdução de SinaisRESUMO
Strongyloides stercoralis hyperinfection causes high mortality rates in humans, and, while hyperinfection can be induced by immunosuppressive glucocorticoids, the pathogenesis remains unknown. Since immunocompetent mice are resistant to infection with S. stercoralis, we hypothesized that NSG mice, which have a reduced innate immune response and lack adaptive immunity, would be susceptible to the infection and develop hyperinfection. Interestingly, despite the presence of large numbers of adult and first-stage larvae in S. stercoralis-infected NSG mice, no hyperinfection was observed even when the mice were treated with a monoclonal antibody to eliminate residual granulocyte activity. NSG mice were then infected with third-stage larvae and treated for 6 wk with methylprednisolone acetate (MPA), a synthetic glucocorticoid. MPA treatment of infected mice resulted in 50% mortality and caused a significant >10-fold increase in the number of parasitic female worms compared with infected untreated mice. In addition, autoinfective third-stage larvae, which initiate hyperinfection, were found in high numbers in MPA-treated, but not untreated, mice. Remarkably, treatment with Δ7-dafachronic acid, an agonist of the parasite nuclear receptor Ss-DAF-12, significantly reduced the worm burden in MPA-treated mice undergoing hyperinfection with S. stercoralis Overall, this study provides a useful mouse model for S. stercoralis autoinfection and suggests a therapeutic strategy for treating lethal hyperinfection.
Assuntos
Colestenos/farmacologia , Metilprednisolona/análogos & derivados , Strongyloides stercoralis/imunologia , Estrongiloidíase/tratamento farmacológico , Estrongiloidíase/imunologia , Animais , Colestenos/efeitos adversos , Feminino , Metilprednisolona/efeitos adversos , Metilprednisolona/farmacologia , Acetato de Metilprednisolona , Camundongos , Estrongiloidíase/patologiaRESUMO
Despite the different physiologic functions of FGF19 and FGF21 as hormonal regulators of fed and fasted metabolism, their pharmacologic administration causes similar increases in energy expenditure, weight loss, and enhanced insulin sensitivity in obese animals. Here, in genetic loss-of-function studies of the shared co-receptor ß-Klotho, we show that these pharmacologic effects are mediated through a common, tissue-specific pathway. Surprisingly, FGF19 and FGF21 actions in liver and adipose tissue are not required for their longer-term weight loss and glycemic effects. In contrast, ß-Klotho in neurons is essential for both FGF19 and FGF21 to cause weight loss and lower glucose and insulin levels. We further show an FGF21 mimetic antibody that activates the FGF receptor 1/ß-Klotho complex also requires neuronal ß-Klotho for its metabolic effects. These studies highlight the importance of the nervous system in mediating the beneficial weight loss and glycemic effects of endocrine FGF drugs.
Assuntos
Anticorpos Monoclonais/farmacologia , Glicemia/efeitos dos fármacos , Fatores de Crescimento de Fibroblastos/farmacologia , Proteínas de Membrana/agonistas , Sistema Nervoso/metabolismo , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/agonistas , Redução de Peso , Tecido Adiposo/metabolismo , Animais , Resistência à Insulina , Proteínas Klotho , Fígado/metabolismo , Proteínas de Membrana/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Obesos , Neurônios/metabolismo , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/imunologiaRESUMO
Parasitic worms infect billions of people worldwide. Current treatments rely on a small group of drugs that have been used for decades. A shortcoming of these drugs is their inability to target the intractable infectious stage of the parasite. As well-known therapeutic targets in mammals, nuclear receptors have begun to be studied in parasitic worms, where they are widely distributed and play key roles in governing metabolic and developmental transcriptional networks. One such nuclear receptor is DAF-12, which is required for normal nematode development, including the all-important infectious stage. Here we review the emerging literature that implicates DAF-12 and potentially other nuclear receptors as novel anthelmintic targets.
Assuntos
Antinematódeos/uso terapêutico , Sistemas de Liberação de Medicamentos/métodos , Proteínas de Helminto , Nematoides , Receptores Citoplasmáticos e Nucleares , Animais , Proteínas de Helminto/agonistas , Proteínas de Helminto/antagonistas & inibidores , Proteínas de Helminto/genética , Proteínas de Helminto/metabolismo , Humanos , Nematoides/genética , Nematoides/metabolismo , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/genética , Infecções por Nematoides/metabolismo , Receptores Citoplasmáticos e Nucleares/agonistas , Receptores Citoplasmáticos e Nucleares/antagonistas & inibidores , Receptores Citoplasmáticos e Nucleares/genética , Receptores Citoplasmáticos e Nucleares/metabolismoRESUMO
The metabolic stress hormone FGF21 is highly expressed in exocrine pancreas, where its levels are increased by refeeding and chemically induced pancreatitis. However, its function in the exocrine pancreas remains unknown. Here, we show that FGF21 stimulates digestive enzyme secretion from pancreatic acinar cells through an autocrine/paracrine mechanism that requires signaling through a tyrosine kinase receptor complex composed of an FGF receptor and ß-Klotho. Mice lacking FGF21 accumulate zymogen granules and are susceptible to pancreatic ER stress, an effect that is reversed by administration of recombinant FGF21. Mice carrying an acinar cell-specific deletion of ß-Klotho also accumulate zymogen granules but are refractory to FGF21-stimulated secretion. Like the classical post-prandial secretagogue, cholecystokinin (CCK), FGF21 triggers intracellular calcium release via PLC-IP3R signaling. However, unlike CCK, FGF21 does not induce protein synthesis, thereby preventing protein accumulation. Thus, pancreatic FGF21 is a digestive enzyme secretagogue whose physiologic function is to maintain acinar cell proteostasis.
Assuntos
Fatores de Crescimento de Fibroblastos/metabolismo , Pâncreas Exócrino/metabolismo , Animais , Comunicação Autócrina , Cálcio/metabolismo , Digestão , Estresse do Retículo Endoplasmático , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Espaço Intracelular/metabolismo , Masculino , Camundongos Knockout , Pâncreas Exócrino/enzimologia , Comunicação Parácrina , Fosfolipase C gama/metabolismo , Biossíntese de Proteínas , Receptores de Fatores de Crescimento de Fibroblastos/metabolismo , Transdução de SinaisRESUMO
Androgen and estrogen biosynthesis in mammals requires the 17,20-lyase activity of cytochrome P450 17A1 (steroid 17-hydroxylase/17,20-lyase). Maximal 17,20-lyase activity in vitro requires the presence of cytochrome b5 (b5), and rare cases of b5 deficiency in human beings causes isolated 17,20-lyase deficiency. To study the consequences of conditional b5 removal from testicular Leydig cells in an animal model, we generated Cyb5(flox/flox):Sf1-Cre (LeyKO) mice. The LeyKO male mice had normal body weights, testis and sex organ weights, and fertility compared with littermates. Basal serum and urine steroid profiles of LeyKO males were not significantly different than littermates. In contrast, marked 17-hydroxyprogesterone accumulation (100-fold basal) and reduced testosterone synthesis (27% of littermates) were observed after human chorionic gonadotropin stimulation in LeyKO animals. Testis homogenates from LeyKO mice showed reduced 17,20-lyase activity and a 3-fold increased 17-hydroxylase to 17,20-lyase activity ratio, which were restored to normal upon addition of recombinant b5. We conclude that Leydig cell b5 is required for maximal androgen synthesis and to prevent 17-hydroxyprogesterone accumulation in the mouse testis; however, the b5-independent 17,20-lyase activity of mouse steroid 17-hydroxylase/17,20-lyase is sufficient for normal male genital development and fertility. LeyKO male mice are a good model for the biochemistry but not the physiology of isolated 17,20-lyase deficiency in human beings.
Assuntos
Citocromos b5/genética , Células Intersticiais do Testículo/enzimologia , Esteroide 17-alfa-Hidroxilase/metabolismo , 17-alfa-Hidroxiprogesterona/sangue , Animais , Citocromos b5/metabolismo , Feminino , Fertilidade , Masculino , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , FenótipoRESUMO
Age-related thymic degeneration is associated with loss of naïve T cells, restriction of peripheral T-cell diversity, and reduced healthspan due to lower immune competence. The mechanistic basis of age-related thymic demise is unclear, but prior evidence suggests that caloric restriction (CR) can slow thymic aging by maintaining thymic epithelial cell integrity and reducing the generation of intrathymic lipid. Here we show that the prolongevity ketogenic hormone fibroblast growth factor 21 (FGF21), a member of the endocrine FGF subfamily, is expressed in thymic stromal cells along with FGF receptors and its obligate coreceptor, ßKlotho. We found that FGF21 expression in thymus declines with age and is induced by CR. Genetic gain of FGF21 function in mice protects against age-related thymic involution with an increase in earliest thymocyte progenitors and cortical thymic epithelial cells. Importantly, FGF21 overexpression reduced intrathymic lipid, increased perithymic brown adipose tissue, and elevated thymic T-cell export and naïve T-cell frequencies in old mice. Conversely, loss of FGF21 function in middle-aged mice accelerated thymic aging, increased lethality, and delayed T-cell reconstitution postirradiation and hematopoietic stem cell transplantation (HSCT). Collectively, FGF21 integrates metabolic and immune systems to prevent thymic injury and may aid in the reestablishment of a diverse T-cell repertoire in cancer patients following HSCT.
Assuntos
Envelhecimento/imunologia , Fatores de Crescimento de Fibroblastos/fisiologia , Imunossenescência , Timo/imunologia , Animais , Camundongos , Camundongos Endogâmicos C57BL , Receptores de Antígenos de Linfócitos T/fisiologia , Linfócitos T/imunologiaRESUMO
Fibroblast growth factor 21 (FGF21) is a hormone induced by various metabolic stresses, including ketogenic and high-carbohydrate diets, that regulates energy homeostasis. In humans, SNPs in and around the FGF21 gene have been associated with macronutrient preference, including carbohydrate, fat, and protein intake. Here we show that FGF21 administration markedly reduces sweet and alcohol preference in mice and sweet preference in cynomolgus monkeys. In mice, these effects require the FGF21 co-receptor ß-Klotho in the central nervous system and correlate with reductions in dopamine concentrations in the nucleus accumbens. Since analogs of FGF21 are currently undergoing clinical evaluation for the treatment of obesity and type 2 diabetes, our findings raise the possibility that FGF21 administration could affect nutrient preference and other reward behaviors in humans.