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Keller T, Koepsell H, Groll J. Evaluation of the Influence of Biosurface Design on the Interaction between the Regulatory Peptide RS1-reg and ODC1 Reveals a Membrane-Dependent Affinity Increase. Adv Biol (Weinh) 2022; 6:e2101108. [PMID: 35735188 DOI: 10.1002/adbi.202101108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 05/07/2022] [Indexed: 01/28/2023]
Abstract
The regulatory solute carrier protein, family 1, member 1 (RS1) modulates via its N-terminal domain RS1-reg the activity of Na+ -d-glucose cotransporter 1 (SGLT1) and thereby the glucose uptake in the small intestine by blocking the release of SGLT1-containing vesicles at the trans-Golgi network (TGN). The antidiabetic activity of RS1 is mediated by ornithindecarboxylase 1 (ODC1), catalyzing the conversion of ornithine to putrescine. Putrescine can bind to a buddying protein complex for SGLT1-containing vesicles at the membrane of the TGN, triggering vesicle release. In this report, a first in-depth analysis of the important binding process between ODC1 and RS1-reg for regulating glucose uptake in the human organism is described by comparing results from the surface-based methods, "surface plasmon resonance" (SPR) and "surface acoustic wave" (SAW) with findings by isothermal titration calorimetry (ITC). In cases of SAW and SPR, three different assay surface setups are compared, resulting in small but significant differences in KD values for different surfaces. Noteworthy, an affinity increase by the factor of about 100 for the interaction is detected and herewith described for the first time in the presence of biological membranes that may be relevant in vivo for the biological function of RS1 and future bespoken antidiabetic drug development.
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Affiliation(s)
- Thorsten Keller
- Department for Functional Materials in Medicine and Dentistry Pleicherwall 2, University of Würzburg, 97070, Würzburg, Germany
| | - Hermann Koepsell
- Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstraße 6, 97070, Würzburg, Germany
| | - Jürgen Groll
- Department for Functional Materials in Medicine and Dentistry Pleicherwall 2, University of Würzburg, 97070, Würzburg, Germany
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2
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A Role for SGLT-2 Inhibitors in Treating Non-diabetic Chronic Kidney Disease. Drugs 2021; 81:1491-1511. [PMID: 34363606 DOI: 10.1007/s40265-021-01573-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2021] [Indexed: 02/06/2023]
Abstract
In recent years, inhibitors of the sodium-glucose co-transporter 2 (SGLT2 inhibitors) have been shown to have significant protective effects on the kidney and the cardiovascular system in patients with diabetes. This effect is also manifested in chronic kidney disease (CKD) patients and is minimally due to improved glycaemic control. Starting from these positive findings, SGLT2 inhibitors have also been tested in patients with non-diabetic CKD or heart failure with reduced ejection fraction. Recently, the DAPA-CKD trial showed a significantly lower risk of CKD progression or death from renal or cardiovascular causes in a mixed population of patients with diabetic and non-diabetic CKD receiving dapagliflozin in comparison with placebo. In patients with heart failure and reduced ejection fraction, two trials (EMPEROR-Reduced and DAPA-HF) also found a significantly lower risk of reaching the secondary renal endpoint in those treated with an SGLT2 inhibitor in comparison with placebo. This also applied to patients with CKD. Apart from their direct mechanism of action, SGLT2 inhibitors have additional effects that could be of particular interest for patients with non-diabetic CKD. Among these, SGLT2 inhibitors reduce blood pressure and serum acid uric levels and can increase hemoglobin levels. Some safety issues should be further explored in the CKD population. SGLT2 inhibitors can minimally increase potassium levels, but this has not been shown by the CREDENCE trial. They also increase magnesium and phosphate reabsorption. These effects could become more significant in patients with advanced CKD and will need monitoring when these agents are used more extensively in the CKD population. Conversely, they do not seem to increase the risk of acute kidney injury.
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Otto C, Friedrich A, Vrhovac Madunić I, Baumeier C, Schwenk RW, Karaica D, Germer CT, Schürmann A, Sabolić I, Koepsell H. Antidiabetic Effects of a Tripeptide That Decreases Abundance of Na +-d-glucose Cotransporter SGLT1 in the Brush-Border Membrane of the Small Intestine. ACS OMEGA 2020; 5:29127-29139. [PMID: 33225144 PMCID: PMC7675577 DOI: 10.1021/acsomega.0c03844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/16/2020] [Indexed: 05/08/2023]
Abstract
In enterocytes, protein RS1 (RSC1A1) mediates an increase of glucose absorption after ingestion of glucose-rich food via upregulation of Na+-d-glucose cotransporter SGLT1 in the brush-border membrane (BBM). Whereas RS1 decelerates the exocytotic pathway of vesicles containing SGLT1 at low glucose levels between meals, RS1-mediated deceleration is relieved after ingestion of glucose-rich food. Regulation of SGLT1 is mediated by RS1 domain RS1-Reg, in which Gln-Ser-Pro (QSP) is effective. In contrast to QSP and RS1-Reg, Gln-Glu-Pro (QEP) and RS1-Reg with a serine to glutamate exchange in the QSP motif downregulate the abundance of SGLT1 in the BBM at high intracellular glucose concentrations by about 50%. We investigated whether oral application of QEP improves diabetes in db/db mice and affects the induction of diabetes in New Zealand obese (NZO) mice under glucolipotoxic conditions. After 6-day administration of drinking water containing 5 mM QEP to db/db mice, fasting glucose was decreased, increase of blood glucose in the oral glucose tolerance test was blunted, and insulin sensitivity was increased. When QEP was added for several days to a high fat/high carbohydrate diet that induced diabetes in NZO mice, the increase of random plasma glucose was prevented, accompanied by lower plasma insulin levels. QEP is considered a lead compound for development of new antidiabetic drugs with more rapid cellular uptake. In contrast to SGLT1 inhibitors, QEP-based drugs may be applied in combination with insulin for the treatment of type 1 and type 2 diabetes, decreasing the required insulin amount, and thereby may reduce the risk of hypoglycemia.
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Affiliation(s)
- Christoph Otto
- Department
of General, Visceral, Transplantation, Vascular and Pediatric Surgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Alexandra Friedrich
- Institute
of Anatomy and Cell Biology, University
of Würzburg, 97070 Würzburg, Germany
| | - Ivana Vrhovac Madunić
- Molecular
Toxicology Unit, Institute for Medical Research
and Occupational Health, 10000 Zagreb, Croatia
| | - Christian Baumeier
- Department
of Experimental Diabetology, German Institute
of Human Nutrition, 14558 Potsdam-Rehbruecke, Germany
- German
Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Robert W. Schwenk
- Department
of Experimental Diabetology, German Institute
of Human Nutrition, 14558 Potsdam-Rehbruecke, Germany
- German
Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Dean Karaica
- Molecular
Toxicology Unit, Institute for Medical Research
and Occupational Health, 10000 Zagreb, Croatia
| | - Christoph-Thomas Germer
- Department
of General, Visceral, Transplantation, Vascular and Pediatric Surgery, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Annette Schürmann
- Department
of Experimental Diabetology, German Institute
of Human Nutrition, 14558 Potsdam-Rehbruecke, Germany
- German
Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Ivan Sabolić
- Molecular
Toxicology Unit, Institute for Medical Research
and Occupational Health, 10000 Zagreb, Croatia
| | - Hermann Koepsell
- Institute
of Anatomy and Cell Biology, University
of Würzburg, 97070 Würzburg, Germany
- . Phone: +49-0151 23532479
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Koepsell H. Glucose transporters in the small intestine in health and disease. Pflugers Arch 2020; 472:1207-1248. [PMID: 32829466 PMCID: PMC7462918 DOI: 10.1007/s00424-020-02439-5] [Citation(s) in RCA: 124] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 07/11/2020] [Accepted: 07/17/2020] [Indexed: 12/23/2022]
Abstract
Absorption of monosaccharides is mainly mediated by Na+-D-glucose cotransporter SGLT1 and the facititative transporters GLUT2 and GLUT5. SGLT1 and GLUT2 are relevant for absorption of D-glucose and D-galactose while GLUT5 is relevant for D-fructose absorption. SGLT1 and GLUT5 are constantly localized in the brush border membrane (BBM) of enterocytes, whereas GLUT2 is localized in the basolateral membrane (BLM) or the BBM plus BLM at low and high luminal D-glucose concentrations, respectively. At high luminal D-glucose, the abundance SGLT1 in the BBM is increased. Hence, D-glucose absorption at low luminal glucose is mediated via SGLT1 in the BBM and GLUT2 in the BLM whereas high-capacity D-glucose absorption at high luminal glucose is mediated by SGLT1 plus GLUT2 in the BBM and GLUT2 in the BLM. The review describes functions and regulations of SGLT1, GLUT2, and GLUT5 in the small intestine including diurnal variations and carbohydrate-dependent regulations. Also, the roles of SGLT1 and GLUT2 for secretion of enterohormones are discussed. Furthermore, diseases are described that are caused by malfunctions of small intestinal monosaccharide transporters, such as glucose-galactose malabsorption, Fanconi syndrome, and fructose intolerance. Moreover, it is reported how diabetes, small intestinal inflammation, parental nutrition, bariatric surgery, and metformin treatment affect expression of monosaccharide transporters in the small intestine. Finally, food components that decrease D-glucose absorption and drugs in development that inhibit or downregulate SGLT1 in the small intestine are compiled. Models for regulations and combined functions of glucose transporters, and for interplay between D-fructose transport and metabolism, are discussed.
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Affiliation(s)
- Hermann Koepsell
- Institute for Anatomy and Cell Biology, University of Würzburg, Koellikerstr 6, 97070, Würzburg, Germany.
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Schäfer N, Rikkala PR, Veyhl-Wichmann M, Keller T, Jurowich CF, Geiger D, Koepsell H. A Modified Tripeptide Motif of RS1 ( RSC1A1) Down-Regulates Exocytotic Pathways of Human Na +-d-glucose Cotransporters SGLT1, SGLT2, and Glucose Sensor SGLT3 in the Presence of Glucose. Mol Pharmacol 2018; 95:82-96. [PMID: 30355744 DOI: 10.1124/mol.118.113514] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 10/19/2018] [Indexed: 12/11/2022] Open
Abstract
A domain of protein RS1 (RSC1A1) called RS1-Reg down-regulates the plasma membrane abundance of Na+-d-glucose cotransporter SGLT1 by blocking the exocytotic pathway at the trans-Golgi. This effect is blunted by intracellular glucose but prevails when serine in a QSP (Gln-Ser-Pro) motif is replaced by glutamate [RS1-Reg(S20E)]. RS1-Reg binds to ornithine decarboxylase (ODC) and inhibits ODC in a glucose-dependent manner. Because the ODC inhibitor difluoromethylornithine (DFMO) acts like RS1-Reg(S20E), and DFMO and RS1-Reg(S20E) are not cumulative, we raised the hypothesis that RS1-Reg(S20E) down-regulates the exocytotic pathway of SGLT1 at the trans-Golgi by inhibiting ODC. We investigated whether QEP down-regulates human SGLT1 (hSGLT1) like hRS1-Reg(S20E) and whether human Na+-d-glucose cotransporter hSGLT2 and the human glucose sensor hSGLT3 are also addressed. We expressed hSGLT1, hSGLT1 linked to yellow fluorescent protein (hSGLT1-YFP), hSGLT2-YFP and hSGLT3-YFP in oocytes of Xenopus laevis, injected hRS1-Reg(S20E), QEP, DFMO, and/or α-methyl-d-glucopyranoside (AMG), and measured AMG uptake, glucose-induced currents, and plasma membrane-associated fluorescence after 1 hour. We also performed in vitro AMG uptake measurements into small intestinal mucosa of mice and human. The data indicate that QEP down-regulates the exocytotic pathway of SGLT1 similar to hRS1-Reg(S20E). Our results suggests that both peptides also down-regulate hSGLT2 and hSGLT3 via the same pathway. Thirty minutes after application of 5 mM QEP in the presence of 5 mM d-glucose, hSGLT1-mediated AMG uptake into small intestinal mucosa was decreased by 40% to 50%. Thus oral application of QEP in a formulation that optimizes uptake into enterocytes but prevents entry into the blood is proposed as novel antidiabetic therapy.
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Affiliation(s)
- Nadine Schäfer
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute (N.S., T.K., D.G., H.K.) and Institute of Anatomy and Cell Biology (P.R.R., M.V.-W., H.K.), University of Würzburg, Würzburg, Germany; and Department of General, Visceral, Vascular, and Paedriatic Surgery, University Hospital of Würzburg, Würzburg, Germany (C.F.J.)
| | - Prashanth Reddy Rikkala
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute (N.S., T.K., D.G., H.K.) and Institute of Anatomy and Cell Biology (P.R.R., M.V.-W., H.K.), University of Würzburg, Würzburg, Germany; and Department of General, Visceral, Vascular, and Paedriatic Surgery, University Hospital of Würzburg, Würzburg, Germany (C.F.J.)
| | - Maike Veyhl-Wichmann
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute (N.S., T.K., D.G., H.K.) and Institute of Anatomy and Cell Biology (P.R.R., M.V.-W., H.K.), University of Würzburg, Würzburg, Germany; and Department of General, Visceral, Vascular, and Paedriatic Surgery, University Hospital of Würzburg, Würzburg, Germany (C.F.J.)
| | - Thorsten Keller
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute (N.S., T.K., D.G., H.K.) and Institute of Anatomy and Cell Biology (P.R.R., M.V.-W., H.K.), University of Würzburg, Würzburg, Germany; and Department of General, Visceral, Vascular, and Paedriatic Surgery, University Hospital of Würzburg, Würzburg, Germany (C.F.J.)
| | - Christian Ferdinand Jurowich
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute (N.S., T.K., D.G., H.K.) and Institute of Anatomy and Cell Biology (P.R.R., M.V.-W., H.K.), University of Würzburg, Würzburg, Germany; and Department of General, Visceral, Vascular, and Paedriatic Surgery, University Hospital of Würzburg, Würzburg, Germany (C.F.J.)
| | - Dietmar Geiger
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute (N.S., T.K., D.G., H.K.) and Institute of Anatomy and Cell Biology (P.R.R., M.V.-W., H.K.), University of Würzburg, Würzburg, Germany; and Department of General, Visceral, Vascular, and Paedriatic Surgery, University Hospital of Würzburg, Würzburg, Germany (C.F.J.)
| | - Hermann Koepsell
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute (N.S., T.K., D.G., H.K.) and Institute of Anatomy and Cell Biology (P.R.R., M.V.-W., H.K.), University of Würzburg, Würzburg, Germany; and Department of General, Visceral, Vascular, and Paedriatic Surgery, University Hospital of Würzburg, Würzburg, Germany (C.F.J.)
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Sebastiani A, Greve F, Gölz C, Förster CY, Koepsell H, Thal SC. RS1 (Rsc1A1) deficiency limits cerebral SGLT1 expression and delays brain damage after experimental traumatic brain injury. J Neurochem 2018; 147:190-203. [PMID: 30022488 DOI: 10.1111/jnc.14551] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/15/2018] [Accepted: 06/19/2018] [Indexed: 01/08/2023]
Abstract
Acute cerebral lesions are associated with dysregulation of brain glucose homeostasis. Previous studies showed that knockdown of Na+ -D-glucose cotransporter SGLT1 impaired outcome after middle cerebral artery occlusion and that widely expressed intracellular RS1 (RSC1A1) is involved in transcriptional and post-translational down-regulation of SGLT1. In the present study, we investigated whether SGLT1 is up-regulated during traumatic brain injury (TBI) and whether removal of RS1 in mice (RS1-KO) influences SGLT1 expression and outcome. Unexpectedly, brain SGLT1 mRNA in RS1-KO was similar to wild-type whereas it was increased in small intestine and decreased in kidney. One day after TBI, SGLT1 mRNA in the ipsilateral cortex was increased 160% in wild-type and 40% in RS1-KO. After RS1 removal lesion volume 1 day after TBI was reduced by 12%, brain edema was reduced by 28%, and motoric disability determined by a beam walking test was improved. In contrast, RS1 removal did neither influence glucose and glycogen accumulation 1 day after TBI nor up-regulation of inflammatory cytokines TNF-α, IL-1β and IL-6 or microglia activation 1 or 5 days after TBI. The data provide proof of principle that inhibition or down-regulation of SGLT1 by targeting RS1 in brain could be beneficial for early treatment of TBI.
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Affiliation(s)
- Anne Sebastiani
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Frederik Greve
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Christina Gölz
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Carola Y Förster
- Department of Anesthesiology, University of Würzburg, Würzburg, Germany
| | - Hermann Koepsell
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany
| | - Serge C Thal
- Department of Anesthesiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
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Shepard BD, Pluznick JL. Saving the sweetness: renal glucose handling in health and disease. Am J Physiol Renal Physiol 2017; 313:F55-F61. [PMID: 28356283 DOI: 10.1152/ajprenal.00046.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/22/2017] [Accepted: 03/22/2017] [Indexed: 12/29/2022] Open
Abstract
Glucose homeostasis is highly controlled, and the function of the kidney plays an integral role in this process. The exquisite control of blood glucose relies, in part, on renal glucose filtration, renal glucose reabsorption, and renal gluconeogenesis. Particularly critical to maintaining glucose homeostasis is the renal reabsorption of glucose; with ~162 g of glucose filtered by the kidney per day, it is imperative that the kidney have the ability to efficiently reabsorb nearly 100% of this glucose back in the bloodstream. In this review, we focus on this central process, highlighting the renal transporters and regulators involved in both the physiology and pathophysiology of glucose reabsorption.
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Affiliation(s)
- Blythe D Shepard
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jennifer L Pluznick
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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