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Telehealth and remote monitoring of a patient’s health status has become more commonplace in the last decade and has been applied to conditions such as heart failure, diabetes mellitus, hypertension, and chronic obstructive pulmonary disease. Conversely, uptake of these technologies to help engender and support home RRTs has lagged. Although studies have looked at the role of telehealth in RRT, they are small and single-centered, and both outcome and cost-effectiveness data are needed to inform future decision making. Furthermore, alignment of payer and government (federal and state) regulations with telehealth procedures is needed along with a better understanding of the viewpoints of the various stakeholders in this process (patients, caregivers, clinicians, payers, dialysis organizations, and government regulators). Despite these barriers, telehealth has great potential to increase the acceptance of home dialysis, and improve outcomes and patient satisfaction while potentially decreasing costs. The Kidney Health Initiative convened a multidisciplinary workgroup to examine the current state of telehealth use in home RRTs as well as outline potential benefits and drawbacks, impediments to implementation, and key unanswered questions.

Goodson, William H. et al., © The Author 2015. Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/ mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety 'Mode of Action' framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology., We gratefully acknowledge the support of the National Institute of Health-National Institute of Environmental Health Sciences (NIEHS) conference grant travel support (R13ES023276); Glenn Rice, Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH, USA also deserves thanks for his thoughtful feedback and inputs on the manuscript; William H.Goodson III was supported by the California Breast Cancer Research Program, Clarence Heller Foundation and California Pacific Medical Center Foundation; Abdul M.Ali would like to acknowledge the financial support of the University of Sultan Zainal Abidin, Malaysia; Ahmed Lasfar was supported by an award from the Rutgers Cancer Institute of New Jersey; Ann-Karin Olsen and Gunnar Brunborg were supported by the Research Council of Norway (RCN) through its Centres of Excellence funding scheme (223268/F50), Amancio Carnero’s lab was supported by grants from the Spanish Ministry of Economy and Competitivity, ISCIII (Fis: PI12/00137, RTICC: RD12/0036/0028) co-funded by FEDER from Regional Development European Funds (European Union), Consejeria de Ciencia e Innovacion (CTS-1848) and Consejeria de Salud of the Junta de Andalucia (PI-0306-2012); Matilde E. Lleonart was supported by a trienal project grant PI12/01104 and by project CP03/00101 for personal support. Amaya Azqueta would like to thank the Ministerio de Educacion y Ciencia (‘Juande la Cierva’ programme, 2009) of the Spanish Government for personal support; Amedeo Amedei was supported by the Italian Ministry of University and Research (2009FZZ4XM_002), and the University of Florence (ex60%2012); Andrew R.Collins was supported by the University of Oslo; Annamaria Colacci was supported by the Emilia-Romagna Region - Project ‘Supersite’ in Italy; Carolyn Baglole was supported by a salary award from the Fonds de recherche du Quebec-Sante (FRQ-S); Chiara Mondello’s laboratory is supported by Fondazione Cariplo in Milan, Italy (grant n. 2011-0370); Christian C.Naus holds a Canada Research Chair; Clement Yedjou was supported by a grant from the National Institutes of Health (NIH-NIMHD grant no. G12MD007581); Daniel C.Koch is supported by the Burroughs Wellcome Fund Postdoctoral Enrichment Award and the Tumor Biology Training grant: NIH T32CA09151; Dean W. Felsher would like to acknowledge the support of United States Department of Health and Human Services, NIH grants (R01 CA170378 PQ22, R01 CA184384, U54 CA149145, U54 CA151459, P50 CA114747 and R21 CA169964); Emilio Rojas would like to thank CONACyT support 152473, Ezio Laconi was supported by AIRC (Italian Association for Cancer Research, grant no. IG 14640) and by the Sardinian Regional Government (RAS); Eun-Yi Moon was supported by grants from the Public Problem-Solving Program (NRF-015M3C8A6A06014500) and Nuclear R&D Program (#2013M2B2A9A03051296 and 2010-0018545) through the National Research Foundation of Korea (NRF) and funded by the Ministry of Education, Science and Technology (MEST) in Korea; Fahd Al-Mulla was supported by the Kuwait Foundation for the Advancement of Sciences (2011-1302-06); Ferdinando Chiaradonna is supported by SysBioNet, a grant for the Italian Roadmap of European Strategy Forum on Research Infrastructures (ESFRI) and by AIRC (Associazione Italiana Ricerca sul Cancro; IG 15364); Francis L.Martin acknowledges funding from Rosemere Cancer Foundation; he also thanks Lancashire Teaching Hospitals NHS trust and the patients who have facilitated the studies he has undertaken over the course of the last 10 years; Gary S.Goldberg would like to acknowledge the support of the New Jersey Health Foundation; Gloria M.Calaf was supported by Fondo Nacional de Ciencia y Tecnología (FONDECYT), Ministerio de Educación de Chile (MINEDUC), Universidad de Tarapacá (UTA); Gudrun Koppen was supported by the Flemish Institute for Technological Research (VITO), Belgium; Hemad Yasaei was supported from a triennial project grant (Strategic Award) from the National Centre for the Replacement, Refinement and Reduction (NC3Rs) of animals in research (NC.K500045.1 and G0800697); Hiroshi Kondoh was supported in part by grants from the Ministry of Education, Culture, Sports, Science, and Technology of Japan, Japan Science and Technology Agency and by JST, CREST; Hsue-Yin Hsu was supported by the Ministry of Science and Technology of Taiwan (NSC93-2314-B-320-006 and NSC94-2314-B-320-002); Hyun Ho Park was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) of the Ministry of Education, Science and Technology (2012R1A2A2A01010870) and a grant from the Korea Healthcare Technology R&D project, Ministry of Health and Welfare, Republic of Korea (HI13C1449); Igor Koturbash is supported by the UAMS/NIH Clinical and Translational Science Award (UL1TR000039 and KL2TR000063) and the Arkansas Biosciences Institute, the major research component of the Arkansas Tobacco Settlement Proceeds Act of 2000; Jan Vondráček acknowledges funding from the Czech Science Foundation (13-07711S); Jesse Roman thanks the NIH for their support (CA116812), John Pierce Wise Sr. and Sandra S.Wise were supported by National Institute of Environmental Health Sciences (ES016893 to J.P.W.) and the Maine Center for Toxicology and Environmental Health; Jonathan Whitfield acknowledges support from the FERO Foundation in Barcelona, Spain; Joseph Christopher is funded by Cancer Research UK and the International Journal of Experimental Pathology; Julia Kravchenko is supported by a philanthropic donation by Fred and Alice Stanback; Jun Sun is supported by a Swim Across America Cancer Research Award; Karine A.Cohen-Solal is supported by a research scholar grant from the American Cancer Society (116683-RSG-09-087-01-TBE); Laetitia Gonzalez received a postdoctoral fellowship from the Fund for Scientific Research–Flanders (FWO-Vlaanderen) and support by an InterUniversity Attraction Pole grant (IAP-P7-07); Laura Soucek is supported by grant #CP10/00656 from the Miguel Servet Research Contract Program and acknowledges support from the FERO Foundation in Barcelona, Spain; Liang-Tzung Lin was supported by funding from the Taipei Medical University (TMU101-AE3-Y19); Linda Gulliver is supported by a Genesis Oncology Trust (NZ) Professional Development Grant, and the Faculty of Medicine, University of Otago, Dunedin, New Zealand; Louis Vermeulen is supported by a Fellowship of the Dutch Cancer Society (KWF, UVA2011-4969) and a grant from the AICR (14–1164); Mahara Valverde would like to thank CONACyT support 153781; Masoud H. Manjili was supported by the office of the Assistant Secretary of Defense for Health Affairs (USA) through the Breast Cancer Research Program under Award No. W81XWH-14-1-0087 Neetu Singh was supported by grant #SR/FT/LS-063/2008 from the Department of Science and Technology, Government of India; Nicole Kleinstreuer is supported by NIEHS contracts (N01-ES 35504 and HHSN27320140003C); P.K. Krishnakumar is supported by the Funding (No. T.K. 11-0629) of King Abdulaziz City for Science and Technology, Riyadh, Saudi Arabia; Paola A.Marignani is supported by the Dalhousie Medical Research Foundation, The Beatrice Hunter Cancer Institute and CIHR and the Nova Scotia Lung Association; Paul Dent is the holder of the Universal Inc.Chair in Signal Transduction Research and is supported with funds from PHS grants from the NIH (R01-CA141704, R01-CA150214, R01-DK52825 and R01-CA61774); Petr Heneberg was supported by the Charles University in Prague projects UNCE 204015 and PRVOUK P31/2012, and by the Czech Science Foundation projects P301/12/1686 and 15-03834Y; Po Sing Leung was supported by the Health and Medical Research Fund of Food and Health Bureau, Hong Kong Special Administrative Region, Ref. No: 10110021; Qiang Cheng was supported in part by grant NSF IIS-1218712; R. Brooks Robey is supported by the United States Department of Veterans Affairs; Rabindra Roy was supported by United States Public Health Service Grants (RO1 CA92306, RO1 CA92306-S1 and RO1 CA113447); Rafaela Andrade-Vieira is supported by the Beatrice Hunter Cancer Research Institute and the Nova Scotia Health Research Foundation, Renza Vento was partially funded by European Regional Development Fund, European Territorial Cooperation 2007–13 (CCI 2007 CB 163 PO 037, OP Italia-Malta 2007–13) and grants from the Italian Ministry of Education, University and Research (MIUR) ex-60%, 2007; Riccardo Di Fiore was a recipient of fellowship granted by European Regional Development Fund, European Territorial Cooperation 2007–2013 (CCI 2007 CB 163 PO 037, OP Italia-Malta 2007–2013); Rita Dornetshuber-Fleiss was supported by the Austrian Science Fund (FWF, project number T 451-B18) and the Johanna Mahlke, geb.-Obermann-Stiftung; Roberta Palorini is supported by a SysBioNet fellowship; Roslida Abd Hamid is supported by the Ministry of Education, Malaysia-Exploratory Research Grant Scheme-Project no: ERGS/1-2013/5527165; Sabine A.S.Langie is the beneficiary of a postdoctoral grant from the AXA Research Fund and the Cefic-LRI Innovative Science Award 2013; Sakina Eltom is supported by NIH grant SC1CA153326; Samira A.Brooks was supported by National Research Service Award (T32 ES007126) from the National Institute of Environmental Health Sciences and the HHMI Translational Medicine Fellowship; Sandra Ryeom was supported by The Garrett B. Smith Foundation and the TedDriven Foundation; Thierry Massfelder was supported by the Institut National de la Santé et de la Recherche Médicale INSERM and Université de Strasbourg; Thomas Sanderson is supported by the Canadian Institutes of Health Research (CIHR; MOP-115019), the Natural Sciences and Engineering Council of Canada (NSERC; 313313) and the California Breast Cancer Research Program (CBCRP; 17UB-8703); Tiziana Guarnieri is supported by a grant from Fundamental Oriented Research (RFO) to the Alma Mater Studiorum University of Bologna, Bologna, Italy and thanks the Fondazione Cassa di Risparmio di Bologna and the Fondazione Banca del Monte di Bologna e Ravenna for supporting the Center for Applied Biomedical Research, S.Orsola-Malpighi University Hospital, Bologna, Italy; W.Kimryn Rathmell is supported by the V Foundation for Cancer Research and the American Cancer Society; William K.Decker was supported in part by grant RP110545 from the Cancer Prevention Research Institute of Texas; William H.Bisson was supported with funding from the NIH P30 ES000210; Yon Rojanasakul was supported with NIH grant R01-ES022968; Zhenbang Chen is supported by NIH grants (MD004038, CA163069 and MD007593); Zhiwei Hu is grateful for the grant support from an institutional start-up fund from The Ohio State University College of Medicine and The OSU James Comprehensive Cancer Center (OSUCCC) and a Seed Award from the OSUCCC Translational Therapeutics Program.

Vascular endothelial growth factor (VEGF) expression is regulated by sequence elements in the 3′ UTR of VEGF mRNA. AUF1/hnRNP D suppresses VEGF 3′ UTR–dependent expression. Peptides with arginine–glycine–glycine motifs derived from AUF1 also suppress VEGF expression., Vascular endothelial growth factor (VEGF) is a regulator of vascularization in development and is a key growth factor in tissue repair. In disease, VEGF contributes to vascularization of solid tumors and arthritic joints. This study examines the role of the mRNA-binding protein AUF1/heterogeneous nuclear ribonucleoprotein D (AUF1) in VEGF gene expression. We show that overexpression of AUF1 in mouse macrophage-like RAW-264.7 cells suppresses endogenous VEGF protein levels. To study 3′ untranslated region (UTR)–mediated regulation, we introduced the 3′ UTR of VEGF mRNA into a luciferase reporter gene. Coexpression of AUF1 represses VEGF-3′ UTR reporter expression in RAW-264.7 cells and in mouse bone marrow–derived macrophages. The C-terminus of AUF1 contains arginine–glycine–glycine (RGG) repeat motifs that are dimethylated. Deletion of the RGG domain of AUF1 eliminated the repressive effects of AUF1. Surprisingly, expression of an AUF1-RGG peptide reduced endogenous VEGF protein levels and repressed VEGF-3′ UTR reporter activity in RAW-264.7 cells. These findings demonstrate that AUF1 regulates VEGF expression, and this study identifies an RGG peptide that suppresses VEGF gene expression.

The current concept is that Tsc-deficient cells are sensitized to apoptosis due to the inhibition of Akt activity by the negative feedback mechanism induced by the hyperactive mTORC1. Unexpectedly, however, we found that Tsc1/2-deficient cells exhibit increased resistance to serum deprivation-induced apoptosis. mTORC1 hyperactivity contributes to the apoptotic resistance of serum-deprived Tsc1/2-deficient cells in part by increasing the growth factor-independent expression of hexokinase II (HKII) and GLUT1. mTORC1-mediated increase in hypoxia-inducible factor 1alpha (HIF1alpha) abundance, which occurs in the absence of serum in normoxic Tsc2-deficient cells, contributes to these changes. Increased HIF1alpha abundance in these cells is attributed to both an increased level and the sustained translation of HIF1alpha mRNA. Sustained glycogen synthase kinase 3beta inhibition and Mcl-1 expression also contribute to the apoptotic resistance of Tsc2-deficient cells to serum deprivation. The inhibition of mTORC1 activity by either rapamycin or Raptor knockdown cannot resensitize these cells to serum deprivation-induced apoptosis because of elevated Akt activity that is an indirect consequence of mTORC1 inhibition. However, the increased HIF1alpha abundance and the maintenance of Mcl-1 protein expression in serum-deprived Tsc2(-/)(-) cells are dependent largely on the hyperactive eIF4E in these cells. Consistently, the reduction of eIF4E levels abrogates the resistance of Tsc2(-/)(-) cells to serum deprivation-induced apoptosis.

Environmental contributions to cancer development are widely accepted, but only a fraction of all pertinent exposures have probably been identified. Traditional toxicological approaches to the problem have largely focused on the effects of individual agents at singular endpoints. As such, they have incompletely addressed both the pro-carcinogenic contributions of environmentally relevant low-dose chemical mixtures and the fact that exposures can influence multiple cancer-associated endpoints over varying timescales. Of these endpoints, dysregulated metabolism is one of the most common and recognizable features of cancer, but its specific roles in exposure-associated cancer development remain poorly understood. Most studies have focused on discrete aspects of cancer metabolism and have incompletely considered both its dynamic integrated nature and the complex controlling influences of substrate availability, external trophic signals and environmental conditions. Emerging high throughput approaches to environmental risk assessment also do not directly address the metabolic causes or consequences of changes in gene expression. As such, there is a compelling need to establish common or complementary frameworks for further exploration that experimentally and conceptually consider the gestalt of cancer metabolism and its causal relationships to both carcinogenesis and the development of other cancer hallmarks. A literature review to identify environmentally relevant exposures unambiguously linked to both cancer development and dysregulated metabolism suggests major gaps in our understanding of exposure-associated carcinogenesis and metabolic reprogramming. Although limited evidence exists to support primary causal roles for metabolism in carcinogenesis, the universality of altered cancer metabolism underscores its fundamental biological importance, and multiple pleiomorphic, even dichotomous, roles for metabolism in promoting, antagonizing or otherwise enabling the development and selection of cancer are suggested.

The serine/threonine protein kinase Akt, also known as protein kinase B (PKB), plays a highly conserved role in the regulation of cellular energy metabolism. Akt is also one of the most frequently activated protein kinases in human cancers, and therefore, represents an attractive potential target for therapeutic intervention. This review will address the possibility that the cancer-promoting activity of Akt is mediated through effects on energy homeostasis that can be specifically targeted to treat cancer.

There is accumulating evidence that cell survival and energy metabolism are inexorably linked. As a major mediator of both the metabolic and anti-apoptotic effects of growth factors, the serine/threonine kinase Akt (also known as protein kinase B or PKB) is particularly well-suited to coordinate the regulation of these interrelated processes. Recent demonstrations that growth factors and Akt require glucose (Glc) to prevent apoptosis and promote cell survival are compatible with this contention, as is a positive correlation between Akt-regulated mitochondrial hexokinase (mtHK) association and apoptotic resistance. From a phylogenetic perspective, the ability of Akt to regulate cellular energy metabolism apparently preceded the capacity to control cell survival, suggesting an evolutionary basis for the Glc dependent anti-apoptotic effects of Akt. We speculate that, somewhere in the course of evolution, the metabolic regulatory function of Akt evolved into an adaptive sensing system involving mtHK that ensures mitochondrial homeostasis, thereby coupling metabolism to cell survival. We also propose that this "guardian" function of mtHK may be specifically exploited for therapeutic purposes.

The serine/threonine kinase Akt/protein kinase B inhibits apoptosis induced by a variety of stimuli, including overexpression or activation of proapoptotic Bcl-2 family members. The precise mechanisms by which Akt prevents apoptosis are not completely understood, but Akt may function to maintain mitochondrial integrity, thereby preventing cytochrome c release following an apoptotic insult. This effect may be mediated, in part, via promotion of physical and functional interactions between mitochondria and hexokinases. Here we show that growth factor deprivation induced proteolytic cleavage of the proapoptotic Bcl-2 family member BID to yield its active truncated form, tBID. Activated Akt inhibited mitochondrial cytochrome c release and apoptosis following BID cleavage. Akt also antagonized tBID-mediated BAX activation and mitochondrial BAK oligomerization, two downstream events thought to be critical for tBID-induced apoptosis. Glucose deprivation, which impaired the ability of Akt to maintain mitochondrion-hexokinase association, prevented Akt from inhibiting BID-mediated apoptosis. Interestingly, tBID independently elicited dissociation of hexokinases from mitochondria, an effect that was antagonized by activated Akt. Ectopic expression of the amino-terminal half of hexokinase II, which is catalytically active and contains the mitochondrion-binding domain, consistently antagonized tBID-induced apoptosis. These results suggest that Akt inhibits BID-mediated apoptosis downstream of BID cleavage via promotion of mitochondrial hexokinase association and antagonism of tBID-mediated BAX and BAK activation at the mitochondria.

Regulation of renal Na-HCO[Formula: see text] cotransporter (NBC1) activity by cholinergic agonists, ANG II, and acute acidosis (CO2) requires both Src family kinase (SFK) and classic MAPK pathway activation. The nonreceptor tyrosine kinase proline-rich tyrosine kinase 2 (Pyk2) couples discrete G protein-coupled receptor and growth factor receptor signaling to SFK activation. We examined the role of Pyk2-SFK interaction in coupling these stimuli to increased NBC1 activity in opossum kidney cells. Carbachol increased tyrosine autophosphorylation of endogenous Pyk2 and ectopically expressed wild-type Pyk2 and were abrogated by kinase-dead mutant (Pyk2-KD) overexpression. Pyk2 phosphorylation was calcium/calmodulin dependent, and Pyk2 associated with Src by means of SH2 domain interaction. Pyk2 phosphorylation and Pyk2-Src interaction by carbachol were mimicked by both ANG II and CO2. To correlate Pyk2 autophosphorylation and Pyk2-Src interaction with NBC activity, cotransporter activity was measured in untransfected cells and in cells overexpressing Pyk2-KD in the presence or absence of carbachol, ANG II, or CO2. In Pyk2-KD-overexpressing cells, the effect of carbachol, ANG II, and CO2was abolished. We conclude that Pyk2 plays a central role in coupling carbachol, ANG II, and CO2to increased NBC activity. This coupling is mediated by Pyk2 autophosphorylation and Pyk2-Src interaction.

Heparin-binding epidermal growth factor -like growth factor (HB-EGF) expression and hexokinase (HK) activity are increased in various pathologic renal conditions. Although the mitogenic properties of HB-EGF have been well characterized, its effects on glucose (Glc) metabolism have not. We therefore examined the possibility that HB-EGF might regulate HK activity and expression in glomerular mesangial cells, which constitute the principal renal cell type affected by a variety of pathologic conditions. Protein kinase C (PKC)-dependent classic mitogen-activated protein kinase (MAPK) pathway activation has been associated with increased HK activity in this cell type, so we also examined dependence upon these signaling intermediates. HB-EGF (> or =10 nm) increased total HK activity over 50% within 12-24 h, an effect mimicked by other EGF receptor agonists, but not by IGF-1 or elevated Glc. EGF receptor and classic MAPK pathway antagonists prevented this increase, as did general inhibitors of gene transcription and protein synthesis. Both HB-EGF and phorbol esters activated the classic MAPK pathway, albeit via PKC-independent and PKC-dependent mechanisms, respectively. Both stimuli were associated with increased HK activity, selectively increased HKII isoform expression, and increased Glc metabolism via both the glycolytic-tricarboxylic acid cycle route and the pentose phosphate pathway. HB-EGF thus constitutes a novel regulator of mesangial cell HK activity and Glc metabolism. HKII is the principal regulated isoform in these cells, as it is in insulin-sensitive peripheral tissues, such as muscle. However, the uniform requirement for classic MAPK pathway activation distinguishes HKII regulation in mesangial cells from that observed in muscle. These findings suggest a novel mechanism whereby growth factors may couple metabolism to glomerular injury.

The epidemic of chronic kidney disease in Nicaragua (Mesoamerican nephropathy) has been linked with recurrent dehydration. Here we tested whether recurrent dehydration may cause renal injury by activation of the polyol pathway, resulting in the generation of endogenous fructose in the kidney that might subsequently induce renal injury via metabolism by fructokinase. Wild-type and fructokinase-deficient mice were subjected to recurrent heat-induced dehydration. One group of each genotype was provided water throughout the day and the other group was hydrated at night, after the dehydration. Both groups received the same total hydration in 24 h. Wild-type mice that received delayed hydration developed renal injury, with elevated serum creatinine, increased urinary NGAL, proximal tubular injury, and renal inflammation and fibrosis. This was associated with activation of the polyol pathway, with increased renal cortical sorbitol and fructose levels. Fructokinase-knockout mice with delayed hydration were protected from renal injury. Thus, recurrent dehydration can induce renal injury via a fructokinase-dependent mechanism, likely from the generation of endogenous fructose via the polyol pathway. Access to sufficient water during the dehydration period can protect mice from developing renal injury. These studies provide a potential mechanism for Mesoamerican nephropathy.

Thrombin is a novel regulator of hexokinase activity in mesangial cells.BackgroundHexokinase (HK) activity is fundamentally important to cellular glucose uptake and metabolism. Phorbol esters increase both HK activity and glucose utilization in cultured mesangial cells via a protein kinase C (PKC)- and extracellular signal-regulated kinases 1 and 2 (ERK1/2)-dependent mechanism. In adult kidneys, increased HK activity has been reported in both glomerular injury and in diabetes, but the mechanisms responsible for these changes are unknown. Thrombin, a known activator of both PKC and ERK1/2, is increased in the settings of renal injury and diabetes. Thus, thrombin may contribute to the observed changes in HK activity in vivo.MethodsThrombin and thrombin receptor agonists were tested for the ability to increase HK activity and glucose metabolism in murine mesangial (SV40 MES 13) cells. ERK1/2 activation was also evaluated in parallel. Thrombin inhibition (hirudins), PKC depletion, Ser-Thr kinase inhibition (H-7), MEK1/2 inhibition (PD98059), pertussis toxin (PTX), and general inhibitors of transcription or translation were then tested for the ability to attenuate these effects.ResultsThrombin (≥0.01 U/mL) mimicked the effect of phorbol esters, increasing HK activity 50% within 12 to 24 hours (P < 0.05). This effect was inhibited by hirudins, mimicked by thrombin receptor agonists, and accompanied by increased Glc utilization. H-7, PD98059, and general inhibitors of transcription or translation—but not PTX—prevented thrombin-induced HK activity at 24 hours. PKC depletion and PD98059 also blocked the associated phosphorylation and activation of ERK1/2.ConclusionsThrombin increases mesangial cell HK activity via a PTX-insensitive mechanism involving thrombin receptor activation, PKC-dependent activation of ERK1/2, and both ongoing gene transcription and de novo protein synthesis. As such, thrombin is a novel regulator of HK activity in mesangial cells and may play a role in coupling renal injury to metabolism.

Phorbol esters increase glucose (Glc) uptake and utilization in a variety of cell types, and, in some cells, these changes have been attributed to increased Glc phosphorylation and better functional coupling of hexokinases (HKs) to facilitative Glc transporters. Phorbol esters are potent mesangial cell mitogens, but their effects on HK-catalyzed Glc phosphorylation and metabolism are unknown. When examined in murine mesangial cells, active, but not inactive, phorbol esters increased HK activity in a time- and dose-dependent manner. Maximal induction of HK activity at 12–24 h was accompanied by parallel increases in both Glc utilization and lactate production and was blocked by the specific MEK1/2 inhibitor PD-98059 (IC50∼3 μM). This effect involved early activation of protein kinase C (PKC), MEK1/2, and ERK1/2, and the prolonged time course of subsequent HK induction was attributable, in part, to requirements for ongoing gene transcription and de novo protein synthesis. Mesangial cell HK activity thus exhibits novel regulatory behavior involving both PKC and classic MAPK pathway activation, suggesting specific mechanisms whereby PKC activation may influence Glc metabolism.

We have previously shown that CO2stimulation of the renal Na-HCO3cotransporter (NBC) activity is abrogated by general inhibitors of protein tyrosine kinases. The more selective inhibitor herbimycin also blocked this effect at concentrations known to preferentially inhibit Src family kinases (SFKs). We therefore examined a role for SFKs in CO2-stimulated NBC activity. To this end, we engineered OK cells to express the COOH-terminal Src kinase (Csk), a negative regulator of SFKs. CO2stimulated NBC activity normally in β-galactosidase-expressing and untransfected control cells. In contrast, Csk-expressing cells had normal baseline NBC activity that was not stimulated by CO2. CO2stimulation increased both total SFK activity and specific tyrosine phosphorylation of Src. The specific MEK1/2 inhibitor PD-98059 completely inhibited the CO2stimulation of NBC activity as well as the accompanying phosphorylation and activation of ERK1/2. Our data suggest the involvement of both SFKs, probably Src, and the “classic” MAPK pathway in mediating CO2-stimulated NBC activity in renal epithelial cells.

In the renal proximal tubule, the activities of the basolateral Na+/HCO3– cotransporter (NBC) and the apical Na+/H+ exchanger (NHE3) uniformly vary in parallel, suggesting that they are coordinately regulated. PKA-mediated inhibition of NHE3 is mediated by a PDZ motif–containing protein, the Na+/H+ exchanger regulatory factor (NHE-RF). Given the common inhibition of these transporters after protein kinase A (PKA) activation, we sought to determine whether NHE-RF also plays a role in PKA-regulated NBC activity. Renal cortex immunoblot analysis using anti-peptide antibodies directed against rabbit NHE-RF demonstrated the presence of this regulatory factor in both brush-border membranes (BBMs) and basolateral membranes (BLMs). Using a reconstitution assay, we found that limited trypsin digestion of detergent solubilized rabbit renal BLM preparations resulted in NBC activity that was unaffected by PKA activation. Co-reconstitution of these trypsinized preparations with a recombinant protein corresponding to wild-type rabbit NHE-RF restored the inhibitory effect of PKA on NBC activity in a concentration-dependent manner. NBC activity was inhibited 60% by 10–8M NHE-RF; this effect was not observed in the absence of PKA. Reconstitution with heat-denatured NHE-RF also failed to attenuate NBC activity. To establish further a physiologic role for NHE-RF in NBC regulation, the renal epithelial cell line B-SC-1, which lacks detectable endogenous NHE-RF expression, was engineered to express stably an NHE-RF transgene. NHE-RF–expressing B-SC-1 cells (B-SC-RF) exhibited markedly lower basal levels of NBC activity than did wild-type controls. Inhibition of NBC activity in B-SC-RF cells was enhanced after 10 μM of forskolin treatment, consistent with a postulated role for NHE-RF in mediating the inhibition of NBC activity by PKA. These findings not only suggest NHE-RF involvement in PKA-regulated NBC activity, but also provide a unique molecular mechanism whereby basolateral NBC and apical NHE3 activities may be coordinately regulated in renal proximal tubule cells. J. Clin. Invest. 104:195–201 (1999).

The hexokinases, by converting glucose to glucose 6-phosphate, help maintain the glucose concentration gradient that results in the movement of glucose into cells through the facilitative glucose transporters. Hexokinase II (HKII) is the major hexokinase isoform in skeletal muscle, heart, and adipose tissue. Insulin induces HKII gene transcription in L6 myotubes, and this, in turn, increases HKII mRNA and the rates of HKII protein synthesis and glucose phosphorylation in these cells. Inhibitors of distinct insulin signaling pathways were used to dissect the molecular mechanism by which HKII gene expression is induced by insulin in L6 myotubes. Treatment with wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI 3-kinase), or with rapamycin, an inhibitor of the pathway from the insulin receptor to p70/p85 ribosomal S6 protein kinase (p70(s6k)), prevented the induction of HKII mRNA by insulin. In contrast, treatment with PD98059, an inhibitor of mitogen-activated protein kinase activation, had no effect on insulin-induced HKII mRNA. In addition, rapamycin blocked the insulin-induced expression of an HKII promoter-chloramphenicol acetyltransferase fusion gene transiently transfected into L6 myotubes, whereas PD98059 had no such effect. These results suggest that a phosphatidylinositol 3-kinase/p70(s6k)-dependent pathway is required for regulation of HKII gene transcription by insulin and that the Ras-mitogen-activated protein kinase-dependent pathway is probably not involved.

Objectives To evaluate the role of GH in colon carcinogenesis, we examined the formation of aberrant crypt foci (ACFs) and tumor development in wild type (WT) and GH-deficient, spontaneous dwarf rats (SDRs) exposed to the carcinogen azoxymethane (AOM). Design ACF were quantified by stereomicroscopy and tumor number and weights were recorded for each animal. Cell proliferation was measured by vincristine metaphase arrest, flow cytometry, and bromodeoxyuridine (BrdU) incorporation. Apoptosis was measured by TUNEL staining and cleaved caspase-3 immunohistochemistry. IGF-I was measured by radioimmunoassay (RIA). Hexokinase activity was measured by spectrophotometric assay. PARP cleavage, and IGF-IR, and p27 kip/cip expression were measured by Western blotting. Results ACFs detected by stereomicroscopy were markedly reduced (∼85%) in SDRs vs. WT rats at 10, 25, and 28 weeks after AOM. Tumor incidence, number, and weight also were reduced in SDR vs. WT animals. AOM treatment increased cell proliferation in the distal colon (where tumors occur) of WT rats but not SDRs, and these changes corresponded to increased ACF and tumor formation. Apoptosis rates were similar in AOM-treated WT and SDRs. Alterations in serum IGF-I levels may contribute to differences in the proliferative response to AOM and decreased ACF formation in SDR vs. WT rats. Conclusions We conclude that early neoplastic lesions (ACFs) were reduced in GH-deficient animals. This effect corresponds with differences in AOM-induced proliferation, but not apoptosis. These data indicate that GH is required for the full effect of AOM on colon ACF and tumor development, and that the SDR rat is a promising model for studies regarding the role ofGH/IGF system in the initiation and promotion of colon cancer.

We have reported that aminopeptidase N/CD13, which metabolizes angiotensin III to angiotensin IV, exhibits greater renal tubular expression in the Dahl salt-resistant (SR/Jr) rat than its salt-sensitive (SS/Jr) counterpart. In this work, aminopeptidase N ( Anpep ) genes from SS/Jr and SR/Jr strains were compared. The coding regions contained only silent single nucleotide polymorphisms between strains. The 5′ flanking regions also contained multiple single nucleotide polymorphisms, which were analyzed by electrophoretic mobility-shift assay using renal epithelial cell (HK-2) nuclear extracts and oligonucleotides corresponding with single nucleotide polymorphism–containing regions. A unique single nucleotide polymorphism 4 nucleotides upstream of a putative CCAAT/enhancer binding protein motif (nucleotides −2256 to −2267) in the 5′ flanking region of the SR/Jr Anpep gene was associated with DNA-protein complex formation, whereas the corresponding sequences in SS rats were not. A chimeric reporter gene containing ≈4.4 Kb of Anpep 5′ flank from the Dahl SR/Jr rat exhibited 2.5- to 3-fold greater expression in HK-2 cells than the corresponding construct derived from the SS strain ( P cis -acting element from the SS rat with that from the SR strain increased reporter gene expression by 2.5-fold ( P Anpep in the Dahl SR/Jr rat. These results highlight a possible association of the Anpep gene with hypertension in Dahl rat and raise the prospect that increased Anpep may play a mechanistic role in adaptation to high salt.

associations between renin -angiotensin system (RAS) hyperactivity and chronic disease are widely recognized ([13][1]). Similar associations between vitamin D (VitD) hypoactivity and chronic disease are also well described ([3][2]). Emerging evidence suggests functional interaction between RAS and

The serine/threonine kinase Akt inhibits mitochondrial cytochrome c release and apoptosis induced by a variety of proapoptotic stimuli. The antiapoptotic activity of Akt is coupled, at least in part, to its effects on cellular metabolism. Here, we provide genetic evidence that Akt is required to maintain hexokinase association with mitochondria. Targeted disruption of this association impairs the ability of growth factors and Akt to inhibit cytochrome c release and apoptosis. Targeted disruption of mitochondria-hexokinase (HK) interaction or exposure to proapoptotic stimuli that promote rapid dissociation of hexokinase from mitochondria potently induce cytochrome c release and apoptosis, even in the absence of Bax and Bak. These effects are inhibited by activated Akt, but not by Bcl-2, implying that changes in outer mitochondrial membrane (OMM) permeability leading to apoptosis can occur in the absence of Bax and Bak and that Akt inhibits these changes through maintenance of hexokinase association with mitochondria.

Mesangial cell hexokinase (HK) activity is increased by a diverse array of factors that share both an association with pathological conditions and a common requirement for classic MAPK pathway activation. To better understand the relationship between glucose (Glc) metabolism and injury and to indirectly test the hypothesis that these changes constitute a general adaptive response to insult, we have sought to identify and characterize injury-associated factors that couple to mesangial cell HK regulation. Proinflammatory interleukin-1 (IL-1) cytokines activate the MAPK pathway and have known salutary effects in this cell type. We therefore examined their ability to influence mesangial cell HK activity, Glc utilization, MAPK pathway activation, and individual HK isoform abundance. IL-1β increased HK activity in both a time- and concentration-dependent manner: activity increased maximally by ∼50% between 12 and 24 h with an apparent EC50of 3 pM. IL-1α mimicked, but did not augment, the effects of IL-1β. Specific IL-1 receptor antagonism and selective MAPK/ERK kinase or upstream Ras inhibition prevented these increases, whereas PKC inhibition did not. Changes in HK activity were associated with both increased Glc metabolism and selective increases in HKII isoform abundance. We conclude that IL-1 cytokines can regulate cellular Glc phosphorylating capacity via an IL-1 receptor-, Ras-, and classic MAPK pathway-mediated increase in HKII abundance. These findings suggest a novel, previously undescribed mechanism whereby metabolism may be coupled to inflammation and injury.

The prototypical extracellular phospholipid mediator, lysophosphatidic acid (LPA), exhibits growth factor-like properties and represents an important survival factor in serum. This potent mesangial cell mitogen is increased in conditions associated with glomerular injury. It is also a known activator of the classic mitogen-activated protein kinase (MAPK) pathway, which plays an important role in the regulation of mesangial cell hexokinase (HK) activity. To better understand the mechanisms coupling metabolism to injury, we examined the ability of LPA to regulate HK activity and expression in cultured murine mesangial cells. LPA increased total HK activity in a concentration- and time-dependent manner, with maximal increases of >50% observed within 12 h of exposure to LPA concentrations ≥25 μM (apparent ED502 μM). These effects were associated with increased extracellular signal-regulated kinase (ERK) activity and were prevented by the pharmacological inhibition of either MAPK/ERK kinase or protein kinase C (PKC). Increased HK activity was also associated with increased glucose (Glc) utilization and lactate accumulation, as well as selectively increased HKII isoform abundance. The ability of exogenous LPA to increase HK activity was both Ca2+independent and pertussis toxin insensitive and was mimicked by LPA-generating phospholipase A2. We conclude that LPA constitutes a novel lipid regulator of mesangial cell HK activity and Glc metabolism. This regulation requires sequential activation of both Ca2+-independent PKC and the classic MAPK pathway and culminates in increased HKII abundance. These previously unrecognized metabolic consequences of LPA stimulation have both physiological and pathophysiological implications. They also suggest a novel mechanism whereby metabolism may be coupled to cellular injury via extracellular lipid mediators.

Heparin-binding epidermal growth factor -like growth factor (HB-EGF) expression and hexokinase (HK) activity are increased in various pathologic renal conditions. Although the mitogenic properties of HB-EGF have been well characterized, its effects on glucose (Glc) metabolism have not. We therefore examined the possibility that HB-EGF might regulate HK activity and expression in glomerular mesangial cells, which constitute the principal renal cell type affected by a variety of pathologic conditions. Protein kinase C (PKC)-dependent classic mitogen-activated protein kinase (MAPK) pathway activation has been associated with increased HK activity in this cell type, so we also examined dependence upon these signaling intermediates. HB-EGF (or =10 nm) increased total HK activity over 50% within 12-24 h, an effect mimicked by other EGF receptor agonists, but not by IGF-1 or elevated Glc. EGF receptor and classic MAPK pathway antagonists prevented this increase, as did general inhibitors of gene transcription and protein synthesis. Both HB-EGF and phorbol esters activated the classic MAPK pathway, albeit via PKC-independent and PKC-dependent mechanisms, respectively. Both stimuli were associated with increased HK activity, selectively increased HKII isoform expression, and increased Glc metabolism via both the glycolytic-tricarboxylic acid cycle route and the pentose phosphate pathway. HB-EGF thus constitutes a novel regulator of mesangial cell HK activity and Glc metabolism. HKII is the principal regulated isoform in these cells, as it is in insulin-sensitive peripheral tissues, such as muscle. However, the uniform requirement for classic MAPK pathway activation distinguishes HKII regulation in mesangial cells from that observed in muscle. These findings suggest a novel mechanism whereby growth factors may couple metabolism to glomerular injury.

Glucose (Glc) metabolism protects cells against oxidant injury. By virtue of their central position in both Glc uptake and utilization, hexokinases (HKs) are ideally suited to contribute to these effects. Compatible with this hypothesis, endogenous HK activity correlates inversely with injury susceptibility in individual renal cell types. We recently reported that ectopic HK expression mimics the anti-apoptotic effects of growth factors in cultured fibroblasts, but anti-apoptotic roles for HKs have not been examined in other cell types or in a cellular injury model. We therefore evaluated HK overexpression for the ability to mitigate acute oxidant-induced cell death in an established epithelial cell culture injury model. In parallel, we examined salutary heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) treatment for the ability to 1) increase endogenous HK activity and 2) mimic the protective effects of ectopic HK expression. Both HK overexpression and HB-EGF increased Glc-phosphorylating capacity and metabolism, and these changes were associated with markedly reduced susceptibility to acute oxidant-induced apoptosis. The uniform Glc dependence of these effects suggests an important adaptive role for Glc metabolism, and for HK activity in particular, in the promotion of epithelial cell survival. These findings also support the contention that HKs contribute to the protective effects of growth factors.

The serine/threonine kinase Akt/PKB is a major downstream effector of growth factor–mediated cell survival. Activated Akt, like Bcl-2 and Bcl-xL, prevents closure of a PT pore component, the voltage-dependent anion channel (VDAC); intracellular acidification; mitochondrial hyperpolarization; and the decline in oxidative phosphorylation that precedes cytochrome c release. However, unlike Bcl-2 and Bcl-xL, the ability of activated Akt to preserve mitochondrial integrity, and thereby inhibit apoptosis, requires glucose availability and is coupled to its metabolism. Hexokinases are known to bind to VDAC and directly couple intramitochondrial ATP synthesis to glucose metabolism. We provide evidence that such coupling serves as a downstream effector function for Akt. First, Akt increases mitochondria-associated hexokinase activity. Second, the antiapoptotic activity of Akt requires only the first committed step of glucose metabolism catalyzed by hexokinase. Finally, ectopic hexokinase expression mimics the ability of Akt to inhibit cytochrome c release and apoptosis. We therefore propose that Akt increases coupling of glucose metabolism to oxidative phosphorylation and regulates PT pore opening via the promotion of hexokinase-VDAC interaction at the outer mitochondrial membrane.

Cholinergic agents are known to affect the epithelial transport of H2O and electrolytes in the kidney. In proximal tubule cells, cholinergic agonists increase basolateral Na-HCO3cotransport activity via M1muscarinic receptor activation. The signaling intermediates that couple these G protein-coupled receptors to cotransporter activation, however, are not well defined. We therefore sought to identify distal effectors of muscarinic receptor activation that contribute to increased NBC activity in cultured proximal tubule cells. As demonstrated previously for acute CO2-regulated cotransport activity, we found that inhibitors of Src family kinases (SFKs) or the classic mitogen-activated protein kinase (MAPK) pathway prevented the stimulation of NBC activity by carbachol. The ability of carbachol to activate Src, as well as the proximal (Raf) and distal [extracellular signal-regulated kinases 1 and 2 (ERK1/2)] elements of the classic MAPK module, was compatible with these findings. Cholinergic stimulation of ERK1/2 activity was also completely prevented by overexpression of a dominant negative mutant of Ras (N17-Ras). Taken together, these findings suggest a requirement for the sequential activation of SFKs, Ras, and the classic MAPK pathway [Raf→MAPK/ERK kinase (MEK)→ERK]. These findings provide important insights into the molecular mechanisms underlying cholinergic regulation of NBC activity in renal epithelial cells. They also suggest a specific mechanism whereby cholinergic stimulation of the kidney can contribute to pH homeostasis.

Transcriptional profiling provides a powerful means for examining global gene expression patterns for possible teleologic relationships without making a priori assumptions [1]. Unfortunately, decisions regarding which data subsets to report are not always exempt from such considerations. Thus, the selective reporting of transcriptosome information can pose a significant dilemma for author and reader alike. The tendency is to publish only those data reflecting the greatest changes. This practice presumes that the largest differences will be the most significant functionally, and in most instances, this is probably a reasonable assumption. However, thresholds for reporting differences vary widely across datasets, primarily on the basis of statistical considerations that are sometimes arbitrary from a physiologic or metabolic perspective. Changes associated with processes involving multiple, functionally redundant species are particularly problematic and may not be individually robust enough for identification. In such cases, incomplete data reporting may inadvertently result in errors of omission that introduce artificial biases or promote misleading functional inferences. The recent report by Kobayashi et al. [2] illustrates some of these potential pitfalls. These authors describe postphagocytic changes in leukocyte transcript abundance for a number of important metabolic genes that are temporally associated with changes in transcript abundance for genes associated with apoptotic susceptibility. The suggestion that this represents a coordinated gene expression program linking metabolism to apoptosis is both intriguing and plausible. However, the accompanying mechanistic inferences are not fully supported by the data, so a few alternative interpretations are considered below. The reported increases in post-phagocytic glucose (Glc) disappearance and lactate accumulation are consistent with increased glycolytic metabolism, although the suggestion that decreased Glc phosphorylating capacity, vis-a-vis hexokinase (HK) activity, contributes to these changes is biochemically implausible. By catalyzing the first committed step of Glc metabolism, the phosphorylation of Glc to yield Glc-6-P, HKs are responsible for the initiation of all physiologically relevant pathways of exogenous Glc utilization. Thus, HKs act proximal to all metabolic pathways invoked to explain the authors’ findings. For example, phosphorylation by HKs is a prerequisite for Glc flux through the pentose phosphate pathway (PPP). The oxidative reactions of this pathway constitute the chief cellular source of reduced nicotinamide adenine dinucleotide phosphate for the bioreduction of glutathione, thioredoxin, and biliverdin. Thus, the reported increase in reduced glutathione content provides strong biochemical evidence of increased PPP flux. However, it is unlikely that primary decreases in cellular Glc phosphorylating capacity would lead to increased PPP flux. Inferences regarding functional coupling between glycolysis and oxidative phosphorylation are similarly problematic, insofar as the coupling reactions are ostensibly dependent on glycolytic flux for substrate provision. These inferences rely largely on transcriptosome information alone. This effectively equates transcript abundance to cognate enzyme function and ignores both the concept of distributive metabolic control and a number of important controlling influences within the cell, including substrate availability, feedback inhibition, and intracellular compartmentalization [3]. Thus, changes in downstream components of individual metabolic flux pathways are insufficient to explain the apparent discrepancy between HK transcript abundance and Glc use. A simpler and more plausible explanation could involve directionally opposite changes in unreported HK isoforms with greater relative contributions to the total, and there is a rational basis for such speculation. Although widely expressed, HKIII does not constitute the principal isoform in any tissue examined [4], including leukocytes, which express several high-affinity HK isoforms [5, 6]. Activities corresponding to HKI and HKIII are well described in these cells, and HKII has been reported in low abundance [6]. However, HKI clearly predominates. Assuming that the microarray is representative of the total expressed leukocyte gene pool, it would be useful to know the magnitude and direction of corresponding changes in HKI and HKII abundance. The proposed link between glycolysis and apoptosis also warrants scrutiny. The authors suggest that decreased expression of HK and antiapoptotic regulators of HK activity (e.g., phosphatidylinositol 3-kinase and Akt) contribute to the increased apoptosis observed in their model. It is important to note, however, that the antiapoptotic effects of these factors are Glc-dependent [7–9]. The corresponding relationship between Glc and cell death is thus fundamentally different and directionally opposite that described by Kobayashi et al. [2]. The reported proapoptotic effects of Glc in the latter case could suggest specific contributions by increased reactive oxygen species generation [10] or uncoupled cytosolic adenosine 5 triphosphate (ATP) hydrolysis [11], changes that would be predicted to functionally oppose some of the suggested meta

SummaryAccelerated glucose metabolism is a common feature of cancer cells. Hexokinases catalyze the first committed step of glucose metabolism. Hexokinase 2 (HK2) is expressed at high level in cancer cells, but only in a limited number of normal adult tissues. Using Hk2 conditional knockout mice, we showed that HK2 is required for tumor initiation and maintenance in mouse models of KRas-driven lung cancer, and ErbB2-driven breast cancer, despite continued HK1 expression. Similarly, HK2 ablation inhibits the neoplastic phenotype of human lung and breast cancer cells in vitro and in vivo. Systemic Hk2 deletion is therapeutic in mice bearing lung tumors without adverse physiological consequences. Hk2 deletion in lung cancer cells suppressed glucose-derived ribonucleotides and impaired glutamine-derived carbon utilization in anaplerosis.

Hexokinases have emerged as novel mediators of the antiapoptotic effects of growth factors in a wide variety of cells. These effects have been attributed to highly regulated direct physical and functional interactions with mitochondria. The demonstration that mitochondrial hexokinases can prevent apoptogenic ‘Bax attack' in proximal tubule cells suggests a need to reexamine the specific contributions of hexokinases and glucose metabolism in this nephron segment and elsewhere within the kidney.