Search

Abstract Polycystic kidney disease (PKD) is a genetic disorder characterized by bilateral cyst formation. We showed that PKD cells and kidneys display metabolic alterations, including the Warburg effect and glutaminolysis, sustained in vitro by the enzyme asparagine synthetase (ASNS). Here, we used antisense oligonucleotides (ASO) against Asns in orthologous and slowly progressive PKD murine models and show that treatment leads to a drastic reduction of total kidney volume (measured by MRI) and a prominent rescue of renal function in the mouse. Mechanistically, the upregulation of an ATF4–ASNS axis in PKD is driven by the amino acid response (AAR) branch of the integrated stress response (ISR). Metabolic profiling of PKD or control kidneys treated with Asns-ASO or Scr-ASO revealed major changes in the mutants, several of which are rescued by Asns silencing in vivo. Indeed, ASNS drives glutamine-dependent de novo pyrimidine synthesis and proliferation in cystic epithelia. Notably, while several metabolic pathways were completely corrected by Asns-ASO, glycolysis was only partially restored. Accordingly, combining the glycolytic inhibitor 2DG with Asns-ASO further improved efficacy. Our studies identify a new therapeutic target and novel metabolic vulnerabilities in PKD.

Abstract Fibrocystin/Polyductin (FPC), encoded by PKHD1, is associated with autosomal recessive polycystic kidney disease (ARPKD), yet its precise role in cystogenesis remains unclear. Here we show that FPC undergoes complex proteolytic processing in developing kidneys, generating three soluble C-terminal fragments (ICDs). Notably, ICD15, contains a novel mitochondrial targeting sequence at its N-terminus, facilitating its translocation into mitochondria. This enhances mitochondrial respiration in renal epithelial cells, partially restoring impaired mitochondrial function caused by FPC loss. FPC inactivation leads to abnormal ultrastructural morphology of mitochondria in kidney tubules without cyst formation. Moreover, FPC inactivation significantly exacerbates renal cystogenesis and triggers severe pancreatic cystogenesis in a Pkd1 mouse mutant Pkd1 V/V in which cleavage of Pkd1-encoded Polycystin-1 at the GPCR Proteolysis Site is blocked. Deleting ICD15 enhances renal cystogenesis without inducing pancreatic cysts in Pkd1 V/V mice. These findings reveal a direct link between FPC and a mitochondrial pathway through ICD15 cleavage, crucial for cystogenesis mechanisms.

Abstract MYC is a key oncogenic driver in multiple tumor types, but concomitantly endows cancer cells with a series of vulnerabilities that provide opportunities for targeted pharmacological intervention. For example, drugs that suppress mitochondrial respiration selectively kill MYC‐overexpressing cells. Here, we unravel the mechanistic basis for this synthetic lethal interaction and exploit it to improve the anticancer effects of the respiratory complex I inhibitor IACS‐010759. In a B‐lymphoid cell line, ectopic MYC activity and treatment with IACS‐010759 added up to induce oxidative stress, with consequent depletion of reduced glutathione and lethal disruption of redox homeostasis. This effect could be enhanced either with inhibitors of NADPH production through the pentose phosphate pathway, or with ascorbate (vitamin C), known to act as a pro‐oxidant at high doses. In these conditions, ascorbate synergized with IACS‐010759 to kill MYC‐overexpressing cells in vitro and reinforced its therapeutic action against human B‐cell lymphoma xenografts. Hence, complex I inhibition and high‐dose ascorbate might improve the outcome of patients affected by high‐grade lymphomas and potentially other MYC‐driven cancers.

Multiple molecular features, such as activation of specific oncogenes (e.g., MYC, BCL2) or a variety of gene expression signatures, have been associated with disease course in diffuse large B‐cell lymphoma (DLBCL), although their relationships and implications for targeted therapy remain to be fully unraveled. We report that MYC activity is closely correlated with—and most likely a driver of—gene signatures related to oxidative phosphorylation (OxPhos) in DLBCL, pointing to OxPhos enzymes, in particular mitochondrial electron transport chain (ETC) complexes, as possible therapeutic targets in high‐grade MYC‐associated lymphomas. In our experiments, indeed, MYC sensitized B cells to the ETC complex I inhibitor IACS‐010759. Mechanistically, IACS‐010759 triggered the integrated stress response (ISR) pathway, driven by the transcription factors ATF4 and CHOP, which engaged the intrinsic apoptosis pathway and lowered the apoptotic threshold in MYC‐overexpressing cells. In line with these findings, the BCL2‐inhibitory compound venetoclax synergized with IACS‐010759 against double‐hit lymphoma (DHL), a high‐grade malignancy with concurrent activation of MYC and BCL2. In BCL2‐negative lymphoma cells, instead, killing by IACS‐010759 was potentiated by the Mcl‐1 inhibitor S63845. Thus, combining an OxPhos inhibitor with select BH3‐mimetic drugs provides a novel therapeutic principle against aggressive, MYC‐associated DLBCL variants.

Este artigo tem como objetivo analisar as respostas dos Estados Unidos e da China em termos de políticas públicas de combate à pandemia da COVID-19, com ênfase no contexto atual de acirramento das tensões geopolíticas, na competição tecnológica e nos modelos de desenvolvimento de ambos os países. Considerando a importância da internet na contemporaneidade para áreas essenciais como economia, política, segurança e defesa, daremos destaque à corrida pela liderança no desenvolvimento das redes 5G. A questão principal que propomos é: qual foi o papel da pandemia na disputa geopolítica entre China e Estados Unidos, considerando sua dimensão tecnológica? A metodologia de pesquisa adotada é a análise qualitativa de documentos oficiais e bibliografia especializada sobre o tema. Nossa hipótese é que a pandemia pode ter conferido vantagem à China na corrida pela liderança no 5G, considerando o maior foco dado pelo governo chinês aos investimentos nessa tecnologia e sua importância no combate à pandemia no país asiático, em que a internet foi essencial para o controle do isolamento social como forma de conter a disseminação do vírus. Os Estados Unidos, por sua vez, concentraram seus esforços no setor de biotecnologia para combater a pandemia.

UNLABELLED: Directional beating of ependymal (E) cells cilia in the walls of the ventricles in the brain is essential for proper CSF flow. E cells display two forms of planar cell polarity (PCP): rotational polarity of individual cilium and translational polarity (asymmetric positioning of cilia in the apical area). The orientation of individual E cells varies according to their location in the ventricular wall (location-specific PCP). It has been hypothesized that hydrodynamic forces on the apical surface of radial glia cells (RGCs), the embryonic precursors of E cells, could guide location-specific PCP in the ventricular epithelium. However, the detection mechanisms for these hydrodynamic forces have not been identified. Here, we show that the mechanosensory proteins polycystic kidney disease 1 (Pkd1) and Pkd2 are present in primary cilia of RGCs. Ablation of Pkd1 or Pkd2 in Nestin-Cre;Pkd1(flox/flox) or Nestin-Cre;Pkd2(flox/flox) mice, affected PCP development in RGCs and E cells. Early shear forces on the ventricular epithelium may activate Pkd1 and Pkd2 in primary cilia of RGCs to properly polarize RGCs and E cells. Consistently, Pkd1, Pkd2, or primary cilia on RGCs were required for the proper asymmetric localization of the PCP protein Vangl2 in E cells apical area. Analyses of single- and double-heterozygous mutants for Pkd1 and/or Vangl2 suggest that these genes function in the same pathway to establish E cells PCP. We conclude that Pkd1 and Pkd2 mechanosensory proteins contribute to the development of brain PCP and prevention of hydrocephalus. SIGNIFICANCE STATEMENT: This study identifies key molecules in the development of planar cell polarity (PCP) in the brain and prevention of hydrocephalus. Multiciliated ependymal (E) cells within the brain ventricular epithelium generate CSF flow through ciliary beating. E cells display location-specific PCP in the orientation and asymmetric positioning of their cilia. Defects in this PCP can result in hydrocephalus. Hydrodynamic forces on radial glial cells (RGCs), the embryonic progenitors of E cells, have been suggested to guide PCP. We show that the mechanosensory proteins Pkd1 and Pkd2 localize to primary cilia in RGCs, and their ablation disrupts the development of PCP in E cells. Early shear forces on RGCs may activate Pkd1 and Pkd2 in RGCs primary cilia to properly orient E cells. This study identifies key molecules in the development of brain PCP and prevention of hydrocephalus.

Summary: Trained immunity (TI) is a de facto innate immune memory program induced in monocytes/macrophages by exposure to pathogens or vaccines, which evolved as protection against infections. TI is characterized by immunometabolic changes and histone post-translational modifications, which enhance production of pro-inflammatory cytokines. As aberrant activation of TI is implicated in inflammatory diseases, tight regulation is critical; however, the mechanisms responsible for this modulation remain elusive. Interleukin-37 (IL-37) is an anti-inflammatory cytokine that curbs inflammation and modulates metabolic pathways. In this study, we show that administration of recombinant IL-37 abrogates the protective effects of TI in vivo, as revealed by reduced host pro-inflammatory responses and survival to disseminated candidiasis. Mechanistically, IL-37 reverses the immunometabolic changes and histone post-translational modifications characteristic of TI in monocytes, thus suppressing cytokine production in response to infection. IL-37 thereby emerges as an inhibitor of TI and as a potential therapeutic target in immune-mediated pathologies.

RESUMO Objetivo: Avaliar características do melanoma em idosos. Método: Pesquisa retrospectiva mediante revisão de prontuários de idosos diagnosticados com melanoma cutâneo primário, no período de 2013 a 2017, atendidos no Hospital Erasto Gaertner, em Curitiba-Paraná. Resultados: Amostra com 139 pacientes, mulheres (52,5%), média de 70,3 anos de idade, com lesão em membro superior ou membro inferior (32,3%) e cabeça (24,4%), sinais de ulceração (33,8%) e classificação em tipo histológico nodular (29,5%), extensivo superficial (27,3%) e acral (11,5%). Média do índice de Breslow de 3,7 mm. Metástases ocorreram em 33% dos pacientes, para linfonodos (36%) e sistema nervoso central (20%). Pesquisa do linfonodo sentinela foi realizada em 41,7% e tratamento cirúrgico isolado em 70% dos casos. Houve recidiva em 34,5% pacientes e 17,9% evoluíram com óbito. Esses achados apontam características prognósticas sombrias relacionadas ao diagnóstico e tratamento tardio da neoplasia. Conclusões: Melanoma em membros e cabeça, índice de Breslow intermediário, metastático para linfonodos e sistema nervoso central, recidiva e tem desfecho fatal. Há necessidade de direcionar estratégias para melhor abordagem da doença em idosos, como prevenção, detecção precoce e oferta de tratamento uniforme e adequado.

Abstract Protein synthesis is traditionally associated with specific cytoplasmic compartments. We now show that OFD1, a centrosomal/basal body protein, interacts with components of the Preinitiation complex of translation (PIC) and of the eukaryotic Initiation Factor (eIF)4F complex and modulates the translation of specific mRNA targets in the kidney. We demonstrate that OFD1 cooperates with the mRNA binding protein Bicc1 to functionally control the protein synthesis machinery at the centrosome where also the PIC and eIF4F components were shown to localize in mammalian cells. Interestingly, Ofd1 and Bicc1 are both involved in renal cystogenesis and selected targets were shown to accumulate in two models of inherited renal cystic disease. Our results suggest a possible role for the centrosome as a specialized station to modulate translation for specific functions of the nearby ciliary structures and may provide functional clues for the understanding of renal cystic disease.

Modeling renal cancer in the mouse has been challenging. We recently showed that upregulation of mechanistic target of rapamycin complex 1 (mTORC1) in a restricted segment of the renal tubule leads to downregulation of the tricarboxylic acid (TCA) cycle enzyme fumarate hydratase, to accumulation of the oncometabolite fumarate, and gradual transformation from benign cysts into cystadenomas and papillary carcinomas.

NRF2 is a transcription factor that coordinates the antioxidant response in many different tissues, ensuring cytoprotection from endogenous and exogenous stress stimuli. In the kidney, its function is essential in appropriate cellular response to oxidative stress, however its aberrant activation supports progression, metastasis, and resistance to therapies in renal cell carcinoma, similarly to what happens in other nonrenal cancers. While at the moment direct inhibitors of NRF2 are not available, understanding the molecular mechanisms that regulate its hyperactivation in specific tumor types is crucial as it may open new therapeutic perspectives. Here, we focus our attention on renal cell carcinoma, describing how NRF2 hyperactivation can contribute to tumor progression and chemoresistance. Furthermore, we highlight the mechanism whereby the many pathways that are generally altered in these tumors converge to dysregulation of the KEAP1-NRF2 axis.

Polycystic kidney disease (PKD) is a ciliopathy resulting from defective localization of membrane proteins such as PC-1 to the primary cilium, resulting in renal cysts, and is associated with another cystic genetic disease called tuberous sclerosis complex (TSC). Here the authors use kidney-specific Tsc1 and Pkd1 mice to show that mTORC1 signalling inhibits PC-1 biogenesis as a potential mechanism of TSC/PKD contiguous gene syndrome.

Abstract non disponibile

Cystic kidney diseases (CKD) is a class of disorders characterized by ciliary dysfunction and, therefore, belonging to the ciliopathies. The prototype CKD is autosomal dominant polycystic kidney disease (ADPKD), whose mutated genes encode for two membrane-bound proteins, polycystin-1 (PC-1) and polycystin-2 (PC-2), of unknown function. Recent studies on CKD-associated genes identified new mechanisms of morphogenesis that are central for establishment and maintenance of proper renal tubular diameter. During embryonic development in the mouse and lower vertebrates a convergent-extension (CE)-like mechanism based on planar cell polarity (PCP) and cellular intercalation is involved in “sculpting” the tubules into a narrow and elongated shape. Once the appropriate diameter is established, further elongation occurs through oriented cell division (OCD). The polycystins (PCs) regulate some of these essential processes. In this review we summarize recent work on the role of PCs in regulating cell migration, the cytoskeleton, and front-rear polarity. These important properties are essential for proper morphogenesis of the renal tubules and the lymphatic vessels. We highlight here several open questions and controversies. Finally, we try to outline some of the next steps required to study these processes and their relevance in physiological and pathological conditions.

MYC is a key oncogenic driver in multiple tumor types, but concomitantly endows cancer cells with a series of vulnerabilities that provide opportunities for targeted pharmacological intervention. For example, drugs that suppress mitochondrial respiration selectively kill MYC‐overexpressing cells. Here, we unravel the mechanistic basis for this synthetic lethal interaction and exploit it to improve the anticancer effects of the respiratory complex I inhibitor IACS‐010759. In a B‐lymphoid cell line, ectopic MYC activity and treatment with IACS‐010759 added up to induce oxidative stress, with consequent depletion of reduced glutathione and lethal disruption of redox homeostasis. This effect could be enhanced either with inhibitors of NADPH production through the pentose phosphate pathway, or with ascorbate (vitamin C), known to act as a pro‐oxidant at high doses. In these conditions, ascorbate synergized with IACS‐010759 to kill MYC‐overexpressing cells in vitro and reinforced its therapeutic action against human B‐cell lymphoma xenografts. Hence, complex I inhibition and high‐dose ascorbate might improve the outcome of patients affected by high‐grade lymphomas and potentially other MYC‐driven cancers. Synopsis: Deregulated expression of the oncogenic transcription factor MYC in B‐cell lymphoma induces a vulnerability to disruption of redox homeostasis by pharmacological treatment with the electron transport chain (ETC) complex I inhibitor IACS‐010759 and high‐dose ascorbate. MYC activation and IACS‐010759 treatment independently cause the buildup of reactive oxygen species (ROS), contributing to their synthetic‐lethal action in B‐cells.Glucose prevents IACS‐010759‐induced cell killing by sustaining the pentose phosphate pathway (PPP)‐dependent production of NADPH, which is then used to regenerate reduced glutathione (GSH), a major cellular antioxidant.High‐dose ascorbate augments IACS‐010759‐induced cell killing through an iron‐dependent pro‐oxidant activity.High‐dose ascorbate and IACS‐010759 show synergistic anti‐tumoral activity in pre‐clinical models of MYC‐driven B‐cell lymphomas. [ABSTRACT FROM AUTHOR]

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disorder characterized by bilateral renal cyst formation (1). Recent identification of signaling cascades deregulated in ADPKD has led to the initiation of several clinical trials, but an approved therapy is still lacking (2), (3). Using a metabolomic approach, we identify a pathogenic pathway in this disease that can be safely targeted for therapy. We show that mutation of PKD1 results in enhanced glycolysis in cells in a mouse model of PKD and in kidneys from humans with ADPKD. Glucose deprivation resulted in lower proliferation and higher apoptotic rates in PKD1-mutant cells than in nondeprived cells. Notably, two distinct PKD mouse models treated with 2-deoxyglucose (2DG), to inhibit glycolysis, had lower kidney weight, volume, cystic index and proliferation rates as compared to nontreated mice. These metabolic alterations depend on the extracellular signal-related kinase (ERK) pathway acting in a dual manner by inhibiting the liver kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) axis on the one hand while activating the mTOR complex 1 (mTORC1)-glycolytic cascade on the other. Enhanced metabolic rates further inhibit AMPK. Forced activation of AMPK acts in a negative feedback loop, restoring normal ERK activity. Taken together, these data indicate that defective glucose metabolism is intimately involved in the pathobiology of ADPKD. Our findings provide a strong rationale for a new therapeutic strategy using existing drugs, either individually or in combination., ADPKD is a chronic progressive disease (1). Cysts originate from any segment of the renal tubule in only 1-5% of the nephrons, a condition that should be compatible with a [...]

During cellular respiration, nutrients are oxidized to generate energy through a mechanism called oxidative phosphorylation, which occurs in the mitochondria. During oxidative phosphorylation, the gradual degradation of molecules through the TCA cycle releases electrons from the covalent bonds that are broken. These electrons are captured by NAD+ through its reduction into NADH. Finally, NADH transports the electrons to the complexes of the electron chain in the internal membrane of mitochondria. These complexes use the energy released by the electrons to pump protons into the intermembrane space, generating an electrochemical gradient across the internal membrane of mitochondria, which provides energy for the ATP-synthase complex, ultimately producing adenosine triphosphate (ATP). We assessed the mitochondrial membrane potential (ψm) using tetramethylrhodamine methyl ester (TMRM), a cell-permeant, cationic, red fluorescent dye. To measure specifically the mitochondrial membrane potential (ψm) we quantified the fluorescence intensity before and after applying FCCP, a mitochondrial electron chain uncoupler. The difference of intensity before and after applying FCCP corresponds specifically to the mitochondrial membrane potential. We analyzed mitochondrial membrane potential (ψm) by cytofluorimetry. The ratio between the total level of signal and the signal generated after uncoupling provided a normalized value for the difference in cell size. Furthermore, to normalize for the different size of cells that we were analyzing we have analyzed TMRM in live imaging using IN Cell Analyzer, so that the level of mitochondrial membrane potential could be detected per unit of mitochondrial membrane area measured. Thus, our protocol can also be used to compare the mitochondrial membrane potential of cells that are different in size.

Cells use glucose to generate energy by two different metabolic processes: lactic fermentation and aerobic respiration. In the first common series of reactions, glucose is converted into pyruvate. In anaerobic conditions, pyruvate is transformed into lactate, this process yields to 2 ATP molecules per glucose molecule. In the presence of oxygen, pyruvate is imported into mitochondria where it is used in the Krebs (or TCA) cycle and oxydative phosphorylation. The global process of oxydative phosphorylation yields to 32 ATP per glucose molecule. For reasons not fully understood, in some pathological cases like cancer, cells use anaerobic glycolysis even in the presence of oxygen, in which case the process is called aerobic glycolysis (or Warburg effect). This results in an increased uptake of glucose and lactate production. Measure of intracellular ATP content and lactate concentrations can provide a readout of aerobic glycolyis.

Il rene policistico autosomico dominante (ADPKD) è una malattia genetica molto comune, caratterizzata dalla formazione di cisti in entrambi i reni. Diverse considerazioni circa i meccanismi genetici e molecolari che stanno alla base della formazione delle cisti in questa malattia sono ancora controverse, ma c'è oggi un ampio consenso sul fatto che la ADPKD sia dovuta alla perdita di funzionalità di uno dei due geni mutati nella malattia, PKD1 o PKD2. In questo breve articolo parleremo in particolare di due aspetti: 1) cercheremo di dare una panoramica sullo stato dell'arte di quanto a oggi compreso sulle basi genetiche e molecolari della malattia, cercando di fornire una visione integrata dei diversi modelli di cistogenesi proposti; 2) forniremo una descrizione dettagliata e un'ampia discussione sui recenti risultati riportati dal nostro laboratorio su un difetto a livello del metabolismo del glucosio nella ADPKD e sulle sue potenziali implicazioni terapeutiche, evidenziando anche la necessità di un'ulteriore validazione dei nostri risultati in altri modelli animali di malattia a esordio tardivo e a progressione lenta.

Mutations in PKD1, the gene encoding for the receptor Polycystin-1 (PC-1), cause autosomal dominant polycystic kidney disease (ADPKD). The cytoplasmic C-terminus of PC-1 contains a coiled-coil domain that mediates an interaction with the PKD2 gene product, Polycystin-2 (PC-2). Here we identify a novel domain in the PC-1 C-terminal tail, a polyproline motif mediating an interaction with Src homology domain 3 (SH3). A screen for interactions using the PC-1 C-terminal tail identified the SH3 domain of nephrocystin-1 (NPHP1) as a potential binding partner of PC-1. NPHP1 is the product of a gene that is mutated in a different form of renal cystic disease, nephronophthisis (NPHP). We show that in vitro pull-down assays and NMR structural studies confirmed the interaction between the PC-1 polyproline motif and the NPHP1 SH3 domain. Furthermore, the two full-length proteins interact through these domains; using a recently generated model system allowing us to track endogenous PC-1, we confirm the interaction between the endogenous proteins. Finally, we show that NPHP1 trafficking to cilia does not require PC-1 and that PC-1 may require NPHP1 to regulate resistance to apoptosis, but not to regulate cell cycle progression. In line with this, we find high levels of apoptosis in renal specimens of NPHP patients. Our data uncover a link between two different ciliopathies, ADPKD and NPHP, supporting the notion that common pathogenetic defects, possibly involving de-regulated apoptosis, underlie renal cyst formation.

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a genetic disorder resulting in large kidney cysts and eventual kidney failure. Mutations in either the PKD1 or PKD2/TRPP2 genes and their respective protein products, polycystin-1 (PC1) and polycystin-2 (PC2) result in ADPKD. PC2 is known to function as a non-selective cation channel, but PC1's function and the function of PC1 cleavage products are not well understood. Here we identify an endogenous PC1 cleavage product, P100, a 100 kDa fragment found in both wild type and epitope tagged PKD1 knock-in mice. Expression of full length human PC1 (FL PC1) and the resulting P100 and C-Terminal Fragment (CTF) cleavage products in both MDCK and CHO cells significantly reduces the store operated Ca(2+) entry (SOCE) resulting from thapsigargin induced store depletion. Exploration into the roles of P100 and CTF in SOCE inhibition reveal that P100, when expressed in Xenopus laevis oocytes, directly inhibits the SOCE currents but CTF does not, nor does P100 when containing the disease causing R4227X mutation. Interestingly, we also found that in PC1 expressing MDCK cells, translocation of the ER Ca(2+) sensor protein STIM1 to the cell periphery was significantly altered. In addition, P100 Co-immunoprecipitates with STIM1 but CTF does not. The expression of P100 in CHO cells recapitulates the STIM1 translocation inhibition seen with FL PC1. These data describe a novel polycystin-1 cleavage product, P100, which functions to reduce SOCE via direct inhibition of STIM1 translocation; a function with consequences for ADPKD.

Autosomal dominant polycystic kidney disease (ADPKD) types 1 and 2 arise as a consequence of mutations in the PKD1 or PKD2 genes, encoding polycystins-1 and -2. Because loss of function of either of the polycystins leads to a very similar phenotype and the two proteins are known to interact, polycystins-1 and -2 are probably active in the same pathway. The way in which loss of either polycystin leads to the development of ADPKD remains to be established, but disturbances of cell calcium regulation are likely to play an important role. Here, we demonstrate that polycystin-1, heterologously expressed in Madin-Darby canine kidney cells, had a pronounced effect on intracellular calcium homeostasis. ATP-induced calcium responses in transfection control cells exhibited a double peak and relatively gradual return to baseline. By contrast, cells expressing heterologous polycystin-1 showed a brief, uniphasic peak and an accelerated rate of decay. Heterologously expressed polycystin-1 accelerated endoplasmic reticulum (ER) calcium reuptake and inhibited capacitative calcium entry; we found no effect of the protein on mitochondrial calcium buffering or plasma membrane calcium extrusion. We therefore propose that polycystin-1 accelerated the decay of the cell calcium response to ATP by upregulation of ER calcium reuptake and consequent minimization of the stimulus for capacitative calcium entry. It is possible that cellular dedifferentiation, fluid secretion, and proliferation might therefore arise in ADPKD as a consequence of disturbances in cytoplasmic and ER calcium homeostasis and aberrant capacitative calcium entry. autosomal dominant polycystic kidney disease; purinergic; calcium signaling; stable transfection; Madin-Darby canine kidney cells

Polycystin-1 (PC-1), the product of the PKD1 gene, mutated in the majority of cases of Autosomal Dominant Polycystic Kidney Disease (ADPKD), is a very large (approximately 520 kDa) plasma membrane receptor localized in several subcellular compartments including cell-cell/matrix junctions as well as cilia. While heterologous over-expression systems have allowed identification of several of the potential biological roles of this receptor, its precise function remains largely elusive. Studying PC-1 in vivo has been a challenging task due to its complexity and low expression levels. To overcome these limitations and facilitate the study of endogenous PC-1, we have inserted HA- or Myc-tag sequences into the Pkd1 locus by homologous recombination. Here, we show that our approach was successful in generating a fully functional and easily detectable endogenous PC-1. Characterization of PC-1 distribution in vivo showed that it is expressed ubiquitously and is developmentally-regulated in most tissues. Furthermore, our novel tool allowed us to investigate the role of PC-1 in brain, where the protein is abundantly expressed. Subcellular localization of PC-1 revealed strong and specific staining in ciliated ependymal and choroid plexus cells. Consistent with this distribution, we observed hydrocephalus formation both in the ubiquitous knock-out embryos and in newborn mice with conditional inactivation of the Pkd1 gene in the brain. Both choroid plexus and ependymal cilia were morphologically normal in these mice, suggesting a role for PC-1 in ciliary function or signalling in this compartment, rather than in ciliogenesis. We propose that the role of PC-1 in the brain cilia might be to prevent hydrocephalus, a previously unrecognized role for this receptor and one that might have important implications for other genetic or sporadic diseases.

Multiple molecular features, such as activation of specific oncogenes (e.g., MYC, BCL2) or a variety of gene expression signatures, have been associated with disease course in diffuse large B‐cell lymphoma (DLBCL), although their relationships and implications for targeted therapy remain to be fully unraveled. We report that MYC activity is closely correlated with—and most likely a driver of—gene signatures related to oxidative phosphorylation (OxPhos) in DLBCL, pointing to OxPhos enzymes, in particular mitochondrial electron transport chain (ETC) complexes, as possible therapeutic targets in high‐grade MYC‐associated lymphomas. In our experiments, indeed, MYC sensitized B cells to the ETC complex I inhibitor IACS‐010759. Mechanistically, IACS‐010759 triggered the integrated stress response (ISR) pathway, driven by the transcription factors ATF4 and CHOP, which engaged the intrinsic apoptosis pathway and lowered the apoptotic threshold in MYC‐overexpressing cells. In line with these findings, the BCL2‐inhibitory compound venetoclax synergized with IACS‐010759 against double‐hit lymphoma (DHL), a high‐grade malignancy with concurrent activation of MYC and BCL2. In BCL2‐negative lymphoma cells, instead, killing by IACS‐010759 was potentiated by the Mcl‐1 inhibitor S63845. Thus, combining an OxPhos inhibitor with select BH3‐mimetic drugs provides a novel therapeutic principle against aggressive, MYC‐associated DLBCL variants. [ABSTRACT FROM AUTHOR]

Research demonstrates that PKD1 and PKD2 encoded gene products have a role in growth regulation. Results indicate that polycystin-1 together with polycystin-2 activates the JAK-STAT pathway and upregulate p21 gene, which lead to inhibition of cell cycle. Further, mutations in either of the genes of the polycystin-1/2 complex affect growth.

Author(s): Kazushige Hanaoka [1, 2]; Feng Qian [2, 3]; Alessandra Boletta [2, 3]; Anil K. Bhunia [3]; Klaus Piontek [3]; Leonidas Tsiokas [4]; Vikas P. Sukhatme [5]; William B. Guggino [...]