Voltage-gated Na⁺ channel activity increases colon cancertranscriptional activity and invasion via persistent MAPK signaling

© 2015 Macmillan Publishers Limited. All rights reserved. Functional expression of voltage-gated Na+ channels (VGSCs) has been demonstrated in multiple cancer cell types where channel activity induces invasive activity. The signaling mechanisms by which VGSCs promote oncogenesis remain poorly understood. We explored the signal transduction process critical to VGSC-mediated invasion on the basis of reports linking channel activity to gene expression changes in excitable cells. Coincidentally, many genes transcriptionally regulated by the SCN5A isoform in colon cancer have an over-representation of cis-acting sites for transcription factors phosphorylated by ERK1/2 MAPK. We hypothesized that VGSC activity promotes MAPK activation to induce transcriptional changes in invasion-related genes. Using pharmacological inhibitors/activators and siRNA-mediated gene knockdowns, we correlated channel activity with Rap1-dependent persistent MAPK activation in the SW620 human colon cancer cell line. We further demonstrated that VGSC activity induces downstream changes in invasion-related gene expression via a PKA/ERK/c-JUN/ELK-1/ETS-1 transcriptional pathway. This is the first study illustrating a molecular mechanism linking functional activity of VGSCs to transcriptional activation of invasion-related genes

A specific insertion of a solo-LTR characterizes the Y-chromosome of Bryonia dioica (Cucurbitaceae)

Background: Relatively few species of flowering plants are dioecious and even fewer are known to have sex chromosomes. Current theory posits that homomorphic sex chromosomes, such as found in Bryonia dioica (Cucurbitaceae), offer insight into the early stages in the evolution of sex chromosomes from autosomes. Little is known about these early steps, but an accumulation of transposable element sequences has been observed on the Ychromosomes of some species with heteromorphic sex chromosomes. Recombination, by which transposable elements are removed, is suppressed on at least part of the emerging Y-chromosome, and this may explain the correlation between the emergence of sex chromosomes and transposable element enrichment. Findings: We sequenced 2321 bp of the Y-chromosome in Bryonia dioica that flank a male-linked marker, BdY1, reported previously. Within this region, which should be suppressed for recombination, we observed a solo-LTR nested in a Copia-like transposable element. We also found other, presumably paralogous, solo-LTRs in a consensus sequence of the underlying Copia-like transposable element. Conclusions: Given that solo-LTRs arise via recombination events, it is noteworthy that we find one in a genomic region where recombination should be suppressed. Although the solo-LTR could have arisen before recombination was suppressed, creating the male-linked marker BdY1, our previous study on B. dioica suggested that BdY1 may not lie in the recombination-suppressed region of the Y-chromosome in all populations. Presence of a solo-LTR near BdY1 therefore fits with the observed correlation between retrotransposon accumulation and the suppression of recombination early in the evolution of sex chromosomes. These findings further suggest that the homomorphic sex chromosomes of B. dioica, the first organism for which genetic XY sex-determination was inferred, are evolutionarily young and offer reference information for comparative studies of other plant sex chromosomes

Involvement of the exomer complex in the polarized transport of Ena1 required for Saccharomyces cerevisiae survival against toxic cations

[EN] Exomer is an adaptor complex required for the direct transport of a selected number of cargoes from the trans-Golgi network (TGN) to the plasma membrane in Saccharomyces cerevisiae However, exomer mutants are highly sensitive to increased concentrations of alkali metal cations, a situation that remains unexplained by the lack of transport of any known cargoes. Here we identify several HAL genes that act as multicopy suppressors of this sensitivity and are connected to the reduced function of the sodium ATPase Ena1. Furthermore, we find that Ena1 is dependent on exomer function. Even though Ena1 can reach the plasma membrane independently of exomer, polarized delivery of Ena1 to the bud requires functional exomer. Moreover, exomer is required for full induction of Ena1 expression after cationic stress by facilitating the plasma membrane recruitment of the molecular machinery involved in Rim101 processing and activation of the RIM101 pathway in response to stress. Both the defective localization and the reduced levels of Ena1 contribute to the sensitivity of exomer mutants to alkali metal cations. Our work thus expands the spectrum of exomer-dependent proteins and provides a link to a more general role of exomer in TGN organization.We acknowledge Emma Keck for English language revision. We also thank members of the Translucent group, J. Arino, J. Ramos, and L. Yenush, for many useful discussions throughout this work and especially L. Yenush for her generous gift of strains and reagents. The help of O. Vincent was essential for developing the work involving RIM101. We also thank R. Valle for her technical assistance at the CR Laboratory. M. Trautwein is acknowledged for data acquisition and discussions during the early stages of the project. C.A. is supported by a USAL predoctoral fellowship. Work at the Spang laboratory was supported by the University of Basel and the Swiss National Science Foundation (31003A-141207 and 310030B-163480). C.R. was supported by grant SA073U14 from the Regional Government of Castilla y Leon and by grant BFU2013-48582-C2-1-P from the CICYT/FEDER Spanish program. J.M.M. acknowledges the financial support from Universitat Politecnica de Valencia project PAID-06-10-1496.Anton, C.; Zanolari, B.; Arcones, I.; Wang, C.; Mulet, JM.; Spang, A.; Roncero, C. (2017). Involvement of the exomer complex in the polarized transport of Ena1 required for Saccharomyces cerevisiae survival against toxic cations. Molecular Biology of the Cell. 28(25):3672-3685. https://doi.org/10.1091/mbc.E17-09-0549S367236852825Ariño, J., Ramos, J., & Sychrová, H. (2010). Alkali Metal Cation Transport and Homeostasis in Yeasts. Microbiology and Molecular Biology Reviews, 74(1), 95-120. doi:10.1128/mmbr.00042-09Bard, F., & Malhotra, V. (2006). The Formation of TGN-to-Plasma-Membrane Transport Carriers. Annual Review of Cell and Developmental Biology, 22(1), 439-455. doi:10.1146/annurev.cellbio.21.012704.133126Barfield, R. M., Fromme, J. C., & Schekman, R. (2009). The Exomer Coat Complex Transports Fus1p to the Plasma Membrane via a Novel Plasma Membrane Sorting Signal in Yeast. Molecular Biology of the Cell, 20(23), 4985-4996. doi:10.1091/mbc.e09-04-0324Bonifacino, J. S. (2014). Adaptor proteins involved in polarized sorting. Journal of Cell Biology, 204(1), 7-17. doi:10.1083/jcb.201310021Bonifacino, J. S., & Glick, B. S. (2004). The Mechanisms of Vesicle Budding and Fusion. Cell, 116(2), 153-166. doi:10.1016/s0092-8674(03)01079-1Bonifacino, J. S., & Lippincott-Schwartz, J. (2003). Coat proteins: shaping membrane transport. Nature Reviews Molecular Cell Biology, 4(5), 409-414. doi:10.1038/nrm1099Carlson, M., & Botstein, D. (1982). Two differentially regulated mRNAs with different 5′ ends encode secreted and intracellular forms of yeast invertase. Cell, 28(1), 145-154. doi:10.1016/0092-8674(82)90384-1Costanzo, M., Baryshnikova, A., Bellay, J., Kim, Y., Spear, E. D., Sevier, C. S., … Mostafavi, S. (2010). The Genetic Landscape of a Cell. Science, 327(5964), 425-431. doi:10.1126/science.1180823De Matteis, M. A., & Luini, A. (2008). Exiting the Golgi complex. Nature Reviews Molecular Cell Biology, 9(4), 273-284. doi:10.1038/nrm2378De Nadal, E., Clotet, J., Posas, F., Serrano, R., Gomez, N., & Arino, J. (1998). The yeast halotolerance determinant Hal3p is an inhibitory subunit of the Ppz1p Ser/Thr protein phosphatase. Proceedings of the National Academy of Sciences, 95(13), 7357-7362. doi:10.1073/pnas.95.13.7357Drubin, D. G., & Nelson, W. J. (1996). Origins of Cell Polarity. Cell, 84(3), 335-344. doi:10.1016/s0092-8674(00)81278-7Fell, G. L., Munson, A. M., Croston, M. A., & Rosenwald, A. G. (2011). Identification of Yeast Genes Involved in K+Homeostasis: Loss of Membrane Traffic Genes Affects K+Uptake. G3: Genes|Genomes|Genetics, 1(1), 43-56. doi:10.1534/g3.111.000166Ferrando, A., Kron, S. J., Rios, G., Fink, G. R., & Serrano, R. (1995). Regulation of cation transport in Saccharomyces cerevisiae by the salt tolerance gene HAL3. Molecular and Cellular Biology, 15(10), 5470-5481. doi:10.1128/mcb.15.10.5470Forsmark, A., Rossi, G., Wadskog, I., Brennwald, P., Warringer, J., & Adler, L. (2011). Quantitative Proteomics of Yeast Post-Golgi Vesicles Reveals a Discriminating Role for Sro7p in Protein Secretion. Traffic, 12(6), 740-753. doi:10.1111/j.1600-0854.2011.01186.xGaber, R. F., Styles, C. A., & Fink, G. R. (1988). TRK1 encodes a plasma membrane protein required for high-affinity potassium transport in Saccharomyces cerevisiae. Molecular and Cellular Biology, 8(7), 2848-2859. doi:10.1128/mcb.8.7.2848Galindo, A., Calcagno-Pizarelli, A. M., Arst, H. N., & Penalva, M. A. (2012). An ordered pathway for the assembly of fungal ESCRT-containing ambient pH signalling complexes at the plasma membrane. Journal of Cell Science, 125(7), 1784-1795. doi:10.1242/jcs.098897Goldstein, A. L., & McCusker, J. H. (1999). Three new dominant drug resistance cassettes for gene disruption inSaccharomyces cerevisiae. Yeast, 15(14), 1541-1553. doi:10.1002/(sici)1097-0061(199910)15:143.0.co;2-kHayashi, M., Fukuzawa, T., Sorimachi, H., & Maeda, T. (2005). Constitutive Activation of the pH-Responsive Rim101 Pathway in Yeast Mutants Defective in Late Steps of the MVB/ESCRT Pathway. Molecular and Cellular Biology, 25(21), 9478-9490. doi:10.1128/mcb.25.21.9478-9490.2005Herrador, A., Herranz, S., Lara, D., & Vincent, O. (2009). Recruitment of the ESCRT Machinery to a Putative Seven-Transmembrane-Domain Receptor Is Mediated by an Arrestin-Related Protein. Molecular and Cellular Biology, 30(4), 897-907. doi:10.1128/mcb.00132-09Herrador, A., Livas, D., Soletto, L., Becuwe, M., Léon, S., & Vincent, O. (2015). Casein kinase 1 controls the activation threshold of an α-arrestin by multisite phosphorylation of the interdomain hinge. Molecular Biology of the Cell, 26(11), 2128-2138. doi:10.1091/mbc.e14-11-1552Herranz, S., Rodriguez, J. M., Bussink, H.-J., Sanchez-Ferrero, J. C., Arst, H. N., Penalva, M. A., & Vincent, O. (2005). Arrestin-related proteins mediate pH signaling in fungi. Proceedings of the National Academy of Sciences, 102(34), 12141-12146. doi:10.1073/pnas.0504776102Hoya, M., Yanguas, F., Moro, S., Prescianotto-Baschong, C., Doncel, C., de León, N., … Valdivieso, M.-H. (2016). Traffic Through theTrans-Golgi Network and the Endosomal System Requires Collaboration Between Exomer and Clathrin Adaptors in Fission Yeast. Genetics, 205(2), 673-690. doi:10.1534/genetics.116.193458Huranova, M., Muruganandam, G., Weiss, M., & Spang, A. (2016). Dynamic assembly of the exomer secretory vesicle cargo adaptor subunits. EMBO reports, 17(2), 202-219. doi:10.15252/embr.201540795Kung, L. F., Pagant, S., Futai, E., D’Arcangelo, J. G., Buchanan, R., Dittmar, J. C., … Miller, E. A. (2011). Sec24p and Sec16p cooperate to regulate the GTP cycle of the COPII coat. The EMBO Journal, 31(4), 1014-1027. doi:10.1038/emboj.2011.444Lamb, T. M., & Mitchell, A. P. (2003). The Transcription Factor Rim101p Governs Ion Tolerance and Cell Differentiation by Direct Repression of the Regulatory Genes NRG1 and SMP1 in Saccharomyces cerevisiae. Molecular and Cellular Biology, 23(2), 677-686. doi:10.1128/mcb.23.2.677-686.2003Lamb, T. M., Xu, W., Diamond, A., & Mitchell, A. P. (2000). Alkaline Response Genes ofSaccharomyces cerevisiaeand Their Relationship to theRIM101Pathway. Journal of Biological Chemistry, 276(3), 1850-1856. doi:10.1074/jbc.m008381200Madrid, R., Gómez, M. J., Ramos, J., & Rodrı́guez-Navarro, A. (1998). Ectopic Potassium Uptake intrk1 trk2Mutants ofSaccharomyces cerevisiaeCorrelates with a Highly Hyperpolarized Membrane Potential. Journal of Biological Chemistry, 273(24), 14838-14844. doi:10.1074/jbc.273.24.14838Maresova, L., & Sychrova, H. (2004). Physiological characterization of Saccharomyces cerevisiae kha1 deletion mutants. Molecular Microbiology, 55(2), 588-600. doi:10.1111/j.1365-2958.2004.04410.xMarqués, M. C., Zamarbide-Forés, S., Pedelini, L., Llopis-Torregrosa, V., & Yenush, L. (2015). A functional Rim101 complex is required for proper accumulation of the Ena1 Na+-ATPase protein in response to salt stress in Saccharomyces cerevisiae. FEMS Yeast Research, 15(4). doi:10.1093/femsyr/fov017Mulet, J. M., Leube, M. P., Kron, S. J., Rios, G., Fink, G. R., & Serrano, R. (1999). A Novel Mechanism of Ion Homeostasis and Salt Tolerance in Yeast: the Hal4 and Hal5 Protein Kinases Modulate the Trk1-Trk2 Potassium Transporter. Molecular and Cellular Biology, 19(5), 3328-3337. doi:10.1128/mcb.19.5.3328Mulet, J. M., & Serrano, R. (2002). Simultaneous determination of potassium and rubidium content in yeast. Yeast, 19(15), 1295-1298. doi:10.1002/yea.909Murguía, J. R., Bellés, J. M., & Serrano, R. (1996). The YeastHAL2Nucleotidase Is anin VivoTarget of Salt Toxicity. Journal of Biological Chemistry, 271(46), 29029-29033. doi:10.1074/jbc.271.46.29029Obara, K., & Kihara, A. (2014). Signaling Events of the Rim101 Pathway Occur at the Plasma Membrane in a Ubiquitination-Dependent Manner. Molecular and Cellular Biology, 34(18), 3525-3534. doi:10.1128/mcb.00408-14Paczkowski, J. E., & Fromme, J. C. (2014). Structural Basis for Membrane Binding and Remodeling by the Exomer Secretory Vesicle Cargo Adaptor. Developmental Cell, 30(5), 610-624. doi:10.1016/j.devcel.2014.07.014Paczkowski, J. E., Richardson, B. C., & Fromme, J. C. (2015). Cargo adaptors: structures illuminate mechanisms regulating vesicle biogenesis. Trends in Cell Biology, 25(7), 408-416. doi:10.1016/j.tcb.2015.02.005Paczkowski, J. E., Richardson, B. C., Strassner, A. M., & Fromme, J. C. (2012). The exomer cargo adaptor structure reveals a novel GTPase-binding domain. The EMBO Journal, 31(21), 4191-4203. doi:10.1038/emboj.2012.268Parsons, A. B., Brost, R. L., Ding, H., Li, Z., Zhang, C., Sheikh, B., … Boone, C. (2003). Integration of chemical-genetic and genetic interaction data links bioactive compounds to cellular target pathways. Nature Biotechnology, 22(1), 62-69. doi:10.1038/nbt919Peñalva, M. A., Lucena-Agell, D., & Arst, H. N. (2014). Liaison alcaline: Pals entice non-endosomal ESCRTs to the plasma membrane for pH signaling. Current Opinion in Microbiology, 22, 49-59. doi:10.1016/j.mib.2014.09.005Ríos, G., Cabedo, M., Rull, B., Yenush, L., Serrano, R., & Mulet, J. M. (2013). Role of the yeast multidrug transporter Qdr2 in cation homeostasis and the oxidative stress response. FEMS Yeast Research, 13(1), 97-106. doi:10.1111/1567-1364.12013RIOS, G., FERRANDO, A., & SERRANO, R. (1997). Mechanisms of Salt Tolerance Conferred by Overexpression of theHAL1 Gene inSaccharomyces cerevisiae. Yeast, 13(6), 515-528. doi:10.1002/(sici)1097-0061(199705)13:63.0.co;2-xRitz, A. M., Trautwein, M., Grassinger, F., & Spang, A. (2014). The Prion-like Domain in the Exomer-Dependent Cargo Pin2 Serves as a trans-Golgi Retention Motif. Cell Reports, 7(1), 249-260. doi:10.1016/j.celrep.2014.02.026Rockenbauch, U., Ritz, A. M., Sacristan, C., Roncero, C., & Spang, A. (2012). The complex interactions of Chs5p, the ChAPs, and the cargo Chs3p. Molecular Biology of the Cell, 23(22), 4402-4415. doi:10.1091/mbc.e11-12-1015Roncero, C. (2002). The genetic complexity of chitin synthesis in fungi. Current Genetics, 41(6), 367-378. doi:10.1007/s00294-002-0318-7Rothfels, K., Tanny, J. C., Molnar, E., Friesen, H., Commisso, C., & Segall, J. (2005). Components of the ESCRT Pathway, DFG16, and YGR122w Are Required for Rim101 To Act as a Corepressor with Nrg1 at the Negative Regulatory Element of the DIT1 Gene of Saccharomyces cerevisiae. Molecular and Cellular Biology, 25(15), 6772-6788. doi:10.1128/mcb.25.15.6772-6788.2005Santos, B., & Snyder, M. (1997). Targeting of Chitin Synthase 3 to Polarized Growth Sites in Yeast Requires Chs5p and Myo2p. Journal of Cell Biology, 136(1), 95-110. doi:10.1083/jcb.136.1.95Sato, M., Dhut, S., & Toda, T. (2005). New drug-resistant cassettes for gene disruption and epitope tagging inSchizosaccharomyces pombe. Yeast, 22(7), 583-591. doi:10.1002/yea.1233Schekman, R., & Orci, L. (1996). Coat Proteins and Vesicle Budding. Science, 271(5255), 1526-1533. doi:10.1126/science.271.5255.1526Sopko, R., Huang, D., Preston, N., Chua, G., Papp, B., Kafadar, K., … Andrews, B. (2006). Mapping Pathways and Phenotypes by Systematic Gene Overexpression. Molecular Cell, 21(3), 319-330. doi:10.1016/j.molcel.2005.12.011Spang, A. (2008). Membrane traffic in the secretory pathway. Cellular and Molecular Life Sciences, 65(18), 2781-2789. doi:10.1007/s00018-008-8349-yStarr, T. L., Pagant, S., Wang, C.-W., & Schekman, R. (2012). Sorting Signals That Mediate Traffic of Chitin Synthase III between the TGN/Endosomes and to the Plasma Membrane in Yeast. PLoS ONE, 7(10), e46386. doi:10.1371/journal.pone.0046386Trautwein, M., Schindler, C., Gauss, R., Dengjel, J., Hartmann, E., & Spang, A. (2006). Arf1p, Chs5p and the ChAPs are required for export of specialized cargo from the Golgi. The EMBO Journal, 25(5), 943-954. doi:10.1038/sj.emboj.7601007Trilla, J. A., Durán, A., & Roncero, C. (1999). Chs7p, a New Protein Involved in the Control of Protein Export from the Endoplasmic Reticulum that Is Specifically Engaged in the Regulation of Chitin Synthesis in Saccharomyces cerevisiae. Journal of Cell Biology, 145(6), 1153-1163. doi:10.1083/jcb.145.6.1153Valdivia, R. H., Baggott, D., Chuang, J. S., & Schekman, R. W. (2002). The Yeast Clathrin Adaptor Protein Complex 1 Is Required for the Efficient Retention of a Subset of Late Golgi Membrane Proteins. Developmental Cell, 2(3), 283-294. doi:10.1016/s1534-5807(02)00127-2Wadskog, I., Forsmark, A., Rossi, G., Konopka, C., Öyen, M., Goksör, M., … Adler, L. (2006). The Yeast Tumor Suppressor Homologue Sro7p Is Required for Targeting of the Sodium Pumping ATPase to the Cell Surface. Molecular Biology of the Cell, 17(12), 4988-5003. doi:10.1091/mbc.e05-08-0798Wang, C.-W., Hamamoto, S., Orci, L., & Schekman, R. (2006). Exomer: a coat complex for transport of select membrane proteins from the trans-Golgi network to the plasma membrane in yeast. Journal of Cell Biology, 174(7), 973-983. doi:10.1083/jcb.200605106Weiskoff, A. M., & Fromme, J. C. (2014). Distinct N-terminal regions of the exomer secretory vesicle cargo Chs3 regulate its trafficking itinerary. Frontiers in Cell and Developmental Biology, 2. doi:10.3389/fcell.2014.00047Yahara, N., Ueda, T., Sato, K., & Nakano, A. (2001). Multiple Roles of Arf1 GTPase in the Yeast Exocytic and Endocytic Pathways. Molecular Biology of the Cell, 12(1), 221-238. doi:10.1091/mbc.12.1.221Yenush, L., Merchan, S., Holmes, J., & Serrano, R. (2005). pH-Responsive, Posttranslational Regulation of the Trk1 Potassium Transporter by the Type 1-Related Ppz1 Phosphatase. Molecular and Cellular Biology, 25(19), 8683-8692. doi:10.1128/mcb.25.19.8683-8692.2005Yenush, L. (2002). The Ppz protein phosphatases are key regulators of K+ and pH homeostasis: implications for salt tolerance, cell wall integrity and cell cycle progression. The EMBO Journal, 21(5), 920-929. doi:10.1093/emboj/21.5.920Zanolari, B., Rockenbauch, U., Trautwein, M., Clay, L., Barral, Y., & Spang, A. (2011). Transport to the plasma membrane is regulated differently early and late in the cell cycle in Saccharomyces cerevisiae. Journal of Cell Science, 124(7), 1055-1066. doi:10.1242/jcs.07237

Analysis of SNPs and Haplotypes in Vitamin D Pathway Genes and Renal Cancer Risk

In the kidney vitamin D is converted to its active form. Since vitamin D exerts its activity through binding to the nuclear vitamin D receptor (VDR), most genetic studies have primarily focused on variation within this gene. Therefore, analysis of genetic variation in VDR and other vitamin D pathway genes may provide insight into the role of vitamin D in renal cell carcinoma (RCC) etiology. RCC cases (N = 777) and controls (N = 1,035) were genotyped to investigate the relationship between RCC risk and variation in eight target genes. Minimum-p-value permutation (Min-P) tests were used to identify genes associated with risk. A three single nucleotide polymorphism (SNP) sliding window was used to identify chromosomal regions with a False Discovery Rate of <10%, where subsequently, haplotype relative risks were computed in Haplostats. Min-P values showed that VDR (p-value = 0.02) and retinoid-X-receptor-alpha (RXRA) (p-value = 0.10) were associated with RCC risk. Within VDR, three haplotypes across two chromosomal regions of interest were identified. The first region, located within intron 2, contained two haplotypes that increased RCC risk by approximately 25%. The second region included a haplotype (rs2239179, rs12717991) across intron 4 that increased risk among participants with the TC (OR = 1.31, 95% CI = 1.09–1.57) haplotype compared to participants with the common haplotype, TT. Across RXRA, one haplotype located 3′ of the coding sequence (rs748964, rs3118523), increased RCC risk 35% among individuals with the variant haplotype compared to those with the most common haplotype. This study comprehensively evaluated genetic variation across eight vitamin D pathway genes in relation to RCC risk. We found increased risk associated with VDR and RXRA. Replication studies are warranted to confirm these findings

Diacylglycerol triggers Rim101 pathway dependent necrosis in yeast: a model for lipotoxicity

The loss of lipid homeostasis can lead to lipid overload and is associated with a variety of disease states. However, little is known as to how the disruption of lipid regulation or lipid overload affects cell survival. In this study we investigated how excess diacylglycerol (DG), a cardinal metabolite suspected to mediate lipotoxicity, compromises the survival of yeast cells. We reveal that increased DG achieved by either genetic manipulation or pharmacological administration of 1,2-dioctanoyl-sn-glycerol (DOG) triggers necrotic cell death. The toxic effects of DG are linked to glucose metabolism and require a functional Rim101 signaling cascade involving the Rim21 dependent sensing complex and activation of a calpain-like protease. The Rim101 cascade is an established pathway that triggers a transcriptional response to alkaline or lipid stress. We propose that the Rim101 pathway senses DG-induced lipid perturbation and conducts a signaling response that either facilitates cellular adaptation or triggers lipotoxic cell death. Using established models of lipotoxicity i.e. high fat diet in Drosophila and palmitic acid administration in cultured human endothelial cells, we present evidence that the core mechanism underlying this calpain-dependent lipotoxic cell death pathway is phylogenetically conserved

Expression and function of G-protein-coupled receptorsin the male reproductive tract

This review focuses on the expression and function of muscarinic acetylcholine receptors (mAChRs), α1-adrenoceptors and relaxin receptors in the male reproductive tract. The localization and differential expression of mAChR and α1-adrenoceptor subtypes in specific compartments of the efferent ductules, epididymis, vas deferens, seminal vesicle and prostate of various species indicate a role for these receptors in the modulation of luminal fluid composition and smooth muscle contraction, including effects on male fertility. Furthermore, the activation of mAChRs induces transactivation of the epidermal growth factor receptor (EGFR) and the Sertoli cell proliferation. The relaxin receptors are present in the testis, RXFP1 in elongated spermatids and Sertoli cells from rat, and RXFP2 in Leydig and germ cells from rat and human, suggesting a role for these receptors in the spermatogenic process. The localization of both receptors in the apical portion of epithelial cells and smooth muscle layers of the vas deferens suggests an involvement of these receptors in the contraction and regulation of secretion.Esta revisão enfatiza a expressão e a função dos receptores muscarínicos, adrenoceptores α1 e receptores para relaxina no sistema reprodutor masculino. A expressão dos receptores muscarínicos e adrenoceptores α1 em compartimentos específicos de dúctulos eferentes, epidídimo, ductos deferentes, vesícula seminal e próstata de várias espécies indica o envolvimento destes receptores na modulação da composição do fluido luminal e na contração do músculo liso, incluindo efeitos na fertilidade masculina. Além disso, a ativação dos receptores muscarínicos leva à transativação do receptor para o fator crescimento epidermal e proliferação das células de Sertoli. Os receptores para relaxina estão presentes no testículo, RXFP1 nas espermátides alongadas e células de Sertoli de rato e RXFP2 nas células de Leydig e germinativas de ratos e humano, sugerindo o envolvimento destes receptores no processo espermatogênico. A localização de ambos os receptores na porção apical das células epiteliais e no músculo liso dos ductos deferentes de rato sugere um papel na contração e na regulação da secreção.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de FarmacologiaUNIFESP, EPM, Depto. de FarmacologiaSciEL