HAMID SAID

Summary

Affiliation: University of California
Country: USA

Publications

  1. pmc Adaptive regulation of human intestinal thiamine uptake by extracellular substrate level: a role for THTR-2 transcriptional regulation
    Svetlana M Nabokina
    VA Medical Center 151, and Long Beach, CA 90822
    Am J Physiol Gastrointest Liver Physiol 305:G593-9. 2013
  2. pmc Recent advances in transport of water-soluble vitamins in organs of the digestive system: a focus on the colon and the pancreas
    Hamid M Said
    VA Medical Center 151, Long Beach, CA 90822
    Am J Physiol Gastrointest Liver Physiol 305:G601-10. 2013
  3. pmc Mammalian colonocytes possess a carrier-mediated mechanism for uptake of vitamin B3 (niacin): studies utilizing human and mouse colonic preparations
    Jeyan S Kumar
    Department of Medicine, University of California, Irvine, CA, USA
    Am J Physiol Gastrointest Liver Physiol 305:G207-13. 2013
  4. pmc Differentiation-dependent regulation of intestinal vitamin B(2) uptake: studies utilizing human-derived intestinal epithelial Caco-2 cells and native rat intestine
    Veedamali S Subramanian
    Department of Medicine, University of California, Irvine, CA, USA
    Am J Physiol Gastrointest Liver Physiol 304:G741-8. 2013
  5. pmc Conditional knockout of the Slc5a6 gene in mouse intestine impairs biotin absorption
    Abhisek Ghosal
    Department of Medicine, University of California, School of Medicine, Irvine, CA, USA
    Am J Physiol Gastrointest Liver Physiol 304:G64-71. 2013
  6. pmc Mechanism and regulation of vitamin B2 (riboflavin) uptake by mouse and human pancreatic β-cells/islets: physiological and molecular aspects
    Abhisek Ghosal
    Department of Medicine and Physiology Biophysics, University of California, Irvine, California, USA
    Am J Physiol Gastrointest Liver Physiol 303:G1052-8. 2012
  7. pmc A high-affinity and specific carrier-mediated mechanism for uptake of thiamine pyrophosphate by human colonic epithelial cells
    Svetlana M Nabokina
    Departments of Medicine and Physiology Biophysics, University of California, Irvine, and Department of Veterans Affairs Medical Center, Long Beach, California 90822, USA
    Am J Physiol Gastrointest Liver Physiol 303:G389-95. 2012
  8. pmc Relative contribution of THTR-1 and THTR-2 in thiamin uptake by pancreatic acinar cells: studies utilizing Slc19a2 and Slc19a3 knockout mouse models
    Veedamali S Subramanian
    Department of Medicine, University of California, Irvine, USA
    Am J Physiol Gastrointest Liver Physiol 302:G572-8. 2012
  9. pmc Knockout of the folate transporter folt-1 causes germline and somatic defects in C. elegans
    Misa U Austin
    Department of Biological Sciences, California State University Pomona, CA 91768, USA
    BMC Dev Biol 10:46. 2010
  10. doi request reprint Intestinal absorption of water-soluble vitamins in health and disease
    Hamid M Said
    School of Medicine, University of California Irvine, Irvine, CA 92697, USA
    Biochem J 437:357-72. 2011

Collaborators

Detail Information

Publications81

  1. pmc Adaptive regulation of human intestinal thiamine uptake by extracellular substrate level: a role for THTR-2 transcriptional regulation
    Svetlana M Nabokina
    VA Medical Center 151, and Long Beach, CA 90822
    Am J Physiol Gastrointest Liver Physiol 305:G593-9. 2013
    ....
  2. pmc Recent advances in transport of water-soluble vitamins in organs of the digestive system: a focus on the colon and the pancreas
    Hamid M Said
    VA Medical Center 151, Long Beach, CA 90822
    Am J Physiol Gastrointest Liver Physiol 305:G601-10. 2013
    ..Significant progress has also been made in understanding the mechanisms involved in the uptake of WSV and the effect of chronic alcohol exposure on the uptake processes. ..
  3. pmc Mammalian colonocytes possess a carrier-mediated mechanism for uptake of vitamin B3 (niacin): studies utilizing human and mouse colonic preparations
    Jeyan S Kumar
    Department of Medicine, University of California, Irvine, CA, USA
    Am J Physiol Gastrointest Liver Physiol 305:G207-13. 2013
    ..These findings report, for the first time, that mammalian colonocytes possess a high-affinity carrier-mediated mechanism for nicotinate uptake and show that the process is affected by intracellular and extracellular factors...
  4. pmc Differentiation-dependent regulation of intestinal vitamin B(2) uptake: studies utilizing human-derived intestinal epithelial Caco-2 cells and native rat intestine
    Veedamali S Subramanian
    Department of Medicine, University of California, Irvine, CA, USA
    Am J Physiol Gastrointest Liver Physiol 304:G741-8. 2013
    ..These findings show, for the first time, that the intestinal RF uptake process undergoes differentiation-dependent upregulation and suggest that this is mediated (at least in part) via transcriptional mechanisms...
  5. pmc Conditional knockout of the Slc5a6 gene in mouse intestine impairs biotin absorption
    Abhisek Ghosal
    Department of Medicine, University of California, School of Medicine, Irvine, CA, USA
    Am J Physiol Gastrointest Liver Physiol 304:G64-71. 2013
    ..These studies also provide evidence for a casual association between SMVT function and normal intestinal health...
  6. pmc Mechanism and regulation of vitamin B2 (riboflavin) uptake by mouse and human pancreatic β-cells/islets: physiological and molecular aspects
    Abhisek Ghosal
    Department of Medicine and Physiology Biophysics, University of California, Irvine, California, USA
    Am J Physiol Gastrointest Liver Physiol 303:G1052-8. 2012
    ..Furthermore, the process appears to be regulated by extracellular and intracellular factors...
  7. pmc A high-affinity and specific carrier-mediated mechanism for uptake of thiamine pyrophosphate by human colonic epithelial cells
    Svetlana M Nabokina
    Departments of Medicine and Physiology Biophysics, University of California, Irvine, and Department of Veterans Affairs Medical Center, Long Beach, California 90822, USA
    Am J Physiol Gastrointest Liver Physiol 303:G389-95. 2012
    ..The results also suggest that the bacterially synthesized TPP in the large intestine is bioavailable and may contribute to overall body homeostasis of vitamin B1 and, especially, to the cellular nutrition of the local colonocytes...
  8. pmc Relative contribution of THTR-1 and THTR-2 in thiamin uptake by pancreatic acinar cells: studies utilizing Slc19a2 and Slc19a3 knockout mouse models
    Veedamali S Subramanian
    Department of Medicine, University of California, Irvine, USA
    Am J Physiol Gastrointest Liver Physiol 302:G572-8. 2012
    ..These findings demonstrate, for the first time, that both mTHTR-1 and mTHTR-2 are involved in carrier-mediated thiamin uptake by pancreatic acinar cells...
  9. pmc Knockout of the folate transporter folt-1 causes germline and somatic defects in C. elegans
    Misa U Austin
    Department of Biological Sciences, California State University Pomona, CA 91768, USA
    BMC Dev Biol 10:46. 2010
    ..A knockout mutation of the gene, folt-1(ok1460), was shown to cause sterility, and here we investigate the source of the sterility and the effect of the folt-1 knockout on somatic function...
  10. doi request reprint Intestinal absorption of water-soluble vitamins in health and disease
    Hamid M Said
    School of Medicine, University of California Irvine, Irvine, CA 92697, USA
    Biochem J 437:357-72. 2011
    ....
  11. pmc Mechanism of riboflavin uptake by cultured human retinal pigment epithelial ARPE-19 cells: possible regulation by an intracellular Ca2+-calmodulin-mediated pathway
    Hamid M Said
    VA Medical Center 151, Long Beach, CA 90822, USA
    J Physiol 566:369-77. 2005
    ....
  12. ncbi request reprint Intestinal absorption of water-soluble vitamins: an update
    Hamid M Said
    University of California School of Medicine, Irvine, California, USA
    Curr Opin Gastroenterol 22:140-6. 2006
    ..Such expansion of knowledge has also covered the field of intestinal absorption of water-soluble vitamins and is the subject of this review...
  13. ncbi request reprint Cellular and molecular aspects of thiamin uptake by human liver cells: studies with cultured HepG2 cells
    Hamid M Said
    Department of Medicine and Physiology, VA Medical Center, Long Beach, CA 90822 5201, USA
    Biochim Biophys Acta 1567:106-12. 2002
    ..In addition, SLC19A2 was found to be the predominant thiamin uptake carrier expressed in these cells and its promoter displays a high level of activity in them...
  14. ncbi request reprint Mechanism of nicotinic acid transport in human liver cells: experiments with HepG2 cells and primary hepatocytes
    Hamid M Said
    Veterans Affairs Medical Center, Long Beach, CA 90822, USA
    Am J Physiol Cell Physiol 293:C1773-8. 2007
    ..These results show, for the first time, the existence of a specific and regulated membrane carrier-mediated system for nicotinic acid transport in human liver cells...
  15. pmc Cell and molecular aspects of human intestinal biotin absorption
    Hamid M Said
    University of California School of Medicine, Irvine, California 92697, USA
    J Nutr 139:158-62. 2009
    ..Intracellular trafficking of the hSMVT protein appears to involve distinct trafficking vesicles that require an intact microtubules network and the motor protein dynein for their mobility...
  16. pmc Pancreatic beta cells and islets take up thiamin by a regulated carrier-mediated process: studies using mice and human pancreatic preparations
    Lisa Mee
    Veterans Affairs Medical Center 151, 5901 E 7th St, Long Beach, CA 90822, USA
    Am J Physiol Gastrointest Liver Physiol 297:G197-206. 2009
    ..Furthermore, clinical mutants of THTR-1 impair thiamin uptake via different mechanisms...
  17. pmc Mechanism and regulation of folate uptake by pancreatic acinar cells: effect of chronic alcohol consumption
    Hamid M Said
    VA Medical Center 151, Long Beach, CA 90822, USA
    Am J Physiol Gastrointest Liver Physiol 298:G985-93. 2010
    ..In addition, chronic alcohol feeding leads to a marked inhibition in folate uptake by pancreatic acinar cells, an effect that is associated with reduction in level of expression of RFC and PCFT...
  18. doi request reprint Biotin: biochemical, physiological and clinical aspects
    Hamid M Said
    University of California School of Medicine, Irvine, CA, USA
    Subcell Biochem 56:1-19. 2012
    ..2000; Said and Seetheram 2006), and thus, for more information the reader is advised to consider these additional sources...
  19. pmc Effect of chronic alcohol exposure on folate uptake by liver mitochondria
    Arundhati Biswas
    Department of Medical Research, Veterans Affairs Medical Center, Long Beach CA 90822, USA
    Am J Physiol Cell Physiol 302:C203-9. 2012
    ....
  20. ncbi request reprint Recent advances in carrier-mediated intestinal absorption of water-soluble vitamins
    Hamid M Said
    University of California School of Medicine, Irvine and VA Medical Center, Long Beach, Long Beach, California 90822, USA
    Annu Rev Physiol 66:419-46. 2004
    ....
  21. ncbi request reprint Riboflavin uptake by the human-derived liver cells Hep G2: mechanism and regulation
    H M Said
    Medical Research Service, VA Medical Center, Long Beach, California 90822, USA
    J Cell Physiol 176:588-94. 1998
    ..Furthermore, the uptake process seems to be regulated by an intracellular Ca2+/calmodulin-mediated pathway and by extracellular substrate levels...
  22. ncbi request reprint Expression and functional contribution of hTHTR-2 in thiamin absorption in human intestine
    Hamid M Said
    Veterans Affairs Medical Center 151, Long Beach, and University of California, Irvine, USA
    Am J Physiol Gastrointest Liver Physiol 286:G491-8. 2004
    ..In addition, results show that this transporter plays a significant role in carrier-mediated thiamin uptake in human intestine...
  23. ncbi request reprint Riboflavin uptake by human-derived colonic epithelial NCM460 cells
    H M Said
    Veterans Affairs Medical Center, Long Beach, CA 90822, USA
    Am J Physiol Cell Physiol 278:C270-6. 2000
    ..It is suggested that the identified transport system may be involved in the absorption of bacterially synthesized RF in the large intestine and that this source of RF may contribute toward RF homeostasis, especially that of colonocytes...
  24. ncbi request reprint Adaptive regulation of intestinal folate uptake: effect of dietary folate deficiency
    H M Said
    University of California Irvine Long Beach Veterans Affairs Medical Program, Long Beach 90822, USA
    Am J Physiol Cell Physiol 279:C1889-95. 2000
    ..Furthermore, the upregulation in folate uptake is associated with an increase in mRNA and protein levels of folate carrier, suggesting possible involvement of a transcriptional regulatory mechanism(s) in the upregulation...
  25. ncbi request reprint A carrier-mediated mechanism for pyridoxine uptake by human intestinal epithelial Caco-2 cells: regulation by a PKA-mediated pathway
    Hamid M Said
    Veterans Affairs Medical Center 151, Long Beach, CA 90822, USA
    Am J Physiol Cell Physiol 285:C1219-25. 2003
    ..This system is pH dependent and amiloride sensitive and appears to be under the regulation of an intracellular PKA-mediated pathway...
  26. ncbi request reprint Mechanism of thiamine uptake by human colonocytes: studies with cultured colonic epithelial cell line NCM460
    H M Said
    Department of Veterans Affairs Medical Center, Long Beach, California 90822, USA
    Am J Physiol Gastrointest Liver Physiol 281:G144-50. 2001
    ..It is suggested that bacterially synthesized thiamine in the large intestine may contribute to thiamine nutrition of the host, especially toward cellular nutrition of the local colonocytes...
  27. ncbi request reprint Mechanism and regulation of vitamin B(6) uptake by renal tubular epithelia: studies with cultured OK cells
    Hamid M Said
    Veterans Affairs Medical Center, Long Beach, California 90822, USA
    Am J Physiol Renal Physiol 282:F465-71. 2002
    ..This mechanism appears to be regulated by extracellular vitamin B(6) levels and an intracellular Ca(2+)/calmodulin-mediated pathway...
  28. pmc Chronic alcohol exposure negatively impacts the physiological and molecular parameters of the renal biotin reabsorption process
    Veedamali S Subramanian
    Departments of Medicine, Physiology, and Biophysics, University of California, Irvine, and Department of Veterans AffairsMedical Center, Long Beach, California, USA
    Am J Physiol Renal Physiol 300:F611-7. 2011
    ..These findings demonstrate for the first time that chronic ethanol feeding inhibits renal biotin transport and that this effect is, at least in part, being exerted at the transcriptional level...
  29. pmc Inhibition of intestinal biotin absorption by chronic alcohol feeding: cellular and molecular mechanisms
    Sandeep B Subramanya
    Departments of Medicine and Physiology Biophysics, University of California, Irvine, USA
    Am J Physiol Gastrointest Liver Physiol 300:G494-501. 2011
    ..These studies identify for the first time the cellular and molecular parameters of the intestinal biotin absorptive processes that are affected by chronic alcohol feeding...
  30. pmc Thiamin uptake by pancreatic acinar cells: effect of chronic alcohol feeding/exposure
    Sandeep B Subramanya
    Department of Medicine and Physiology Biophysics, University of California, Irvine, USA
    Am J Physiol Gastrointest Liver Physiol 301:G896-904. 2011
    ..Furthermore, chronic alcohol feeding also negatively impacts intracellular parameters of thiamin metabolism in pancreatic acinar cells...
  31. pmc Structure-function activity of the human sodium-dependent multivitamin transporter: role of His¹¹⁵ and His²⁵⁴
    Abhisek Ghosal
    Department of Medicine, University of California, Irvine, USA
    Am J Physiol Cell Physiol 300:C97-104. 2011
    ..Our results show important role for His¹¹⁵ and His²⁵⁴ residues in hSMVT function, which is most probably mediated via an effect on level of hSMVT expression at the cell membrane...
  32. pmc Tspan-1 interacts with the thiamine transporter-1 in human intestinal epithelial cells and modulates its stability
    Svetlana M Nabokina
    Department of Medicine, University of California, Irvine, USA
    Am J Physiol Gastrointest Liver Physiol 301:G808-13. 2011
    ..These studies demonstrate for the first time that Tspan-1 is an interacting partner with hTHTR-1 and that this interaction affects hTHTR-1 stability...
  33. pmc Vitamin B1 (thiamine) uptake by human retinal pigment epithelial (ARPE-19) cells: mechanism and regulation
    Veedamali S Subramanian
    Department of Medicine Nephrology, University of California, Irvine, CA 92697, USA
    J Physiol 582:73-85. 2007
    ..Further, clinically relevant mutations in hTHTR-1 lead to impaired cell surface expression or function of the transporter in retinal epithelial ARPE-19 cells...
  34. ncbi request reprint Targeting and trafficking of the human thiamine transporter-2 in epithelial cells
    Veedamali S Subramanian
    Department of Medicine, The University of California, Irvine, California 92697, USA
    J Biol Chem 281:5233-45. 2006
    ..Finally, we compared the behavior of hTHTR2 with that of hTHTR1 and the human reduced folate carrier (SLC19A1) to underscore commonalities in the cell surface targeting mechanisms of the entire SLC19A gene family...
  35. ncbi request reprint Differentiation-dependent up-regulation of intestinal thiamin uptake: cellular and molecular mechanisms
    Svetlana M Nabokina
    Veteran Affairs Healthcare System, Long Beach, California 90822, USA
    J Biol Chem 280:32676-82. 2005
    ....
  36. ncbi request reprint Intracellular trafficking and membrane targeting mechanisms of the human reduced folate carrier in Mammalian epithelial cells
    Jonathan S Marchant
    Department of Neurobiology and Behavior, University of California, Irvine, California 92697, USA
    J Biol Chem 277:33325-33. 2002
    ..For the first time, these data define the mechanisms that control the intracellular trafficking and cell surface localization of hRFC within mammalian epithelia...
  37. ncbi request reprint Biotin-responsive basal ganglia disease-linked mutations inhibit thiamine transport via hTHTR2: biotin is not a substrate for hTHTR2
    Veedamali S Subramanian
    Dept of Medicine, University of California, Irvine, USA
    Am J Physiol Cell Physiol 291:C851-9. 2006
    ..These results cast doubt on the most parsimonious explanation for the BBGD phenotype, namely that hTHTR2 is a physiological biotin transporter...
  38. ncbi request reprint Biotin uptake by human proximal tubular epithelial cells: cellular and molecular aspects
    Krishnaswamy Balamurugan
    VA Medical Center 151, Long Beach, CA 90822, USA
    Am J Physiol Renal Physiol 288:F823-31. 2005
    ..The uptake process appears to be adaptively regulated by extracellular biotin level, which involves transcriptional regulatory mechanism(s)...
  39. ncbi request reprint Tight junction targeting and intracellular trafficking of occludin in polarized epithelial cells
    Veedamali S Subramanian
    Department of Medicine, University of California, Irvine, California, USA
    Am J Physiol Cell Physiol 293:C1717-26. 2007
    ..In contrast, the steady-state localization of occludin at the cell surface was dependent on intact microfilaments but not microtubules...
  40. ncbi request reprint Apical membrane targeting and trafficking of the human proton-coupled transporter in polarized epithelia
    Veedamali S Subramanian
    Departments of Medicine, University of California, Irvine, California, USA
    Am J Physiol Cell Physiol 294:C233-40. 2008
    ..For the first time, our data present information regarding structure-function and membrane targeting of the hPCFT polypeptide, as well as the mechanisms that control its steady-state expression in polarized cells...
  41. ncbi request reprint Effect of folate oversupplementation on folate uptake by human intestinal and renal epithelial cells
    Balasubramaniem Ashokkumar
    Department of Medicine, Division of Nephrology, and the Department of Physiology and Biophysics, University of California, Irvine, CA, USA
    Am J Clin Nutr 86:159-66. 2007
    ..Hence, food fortification and intake of supplemental folate are widespread...
  42. pmc Enteropathogenic Escherichia coli inhibits intestinal vitamin B1 (thiamin) uptake: studies with human-derived intestinal epithelial Caco-2 cells
    Balasubramaniem Ashokkumar
    Department of Medical Research, Veterans Administration Medical Center, Long Beach, California 90822, USA
    Am J Physiol Gastrointest Liver Physiol 297:G825-33. 2009
    ..Furthermore, the inhibition appears to be dependent on a functional TTSS of EPEC...
  43. pmc Membrane targeting and intracellular trafficking of the human sodium-dependent multivitamin transporter in polarized epithelial cells
    Veedamali S Subramanian
    Department of Medicine, University of California, Irvine, USA
    Am J Physiol Cell Physiol 296:C663-71. 2009
    ..Third, apical targeting was lost on deletion of a helical-prone region between amino acids 570-584. We conclude that the COOH tail of hSMVT contains several determinants important for polarized targeting and biotin transport...
  44. ncbi request reprint Thiamin uptake by the human-derived renal epithelial (HEK-293) cells: cellular and molecular mechanisms
    Balasubramaniem Ashokkumar
    Department of Medicine, University of California, Irvine, CA, USA
    Am J Physiol Renal Physiol 291:F796-805. 2006
    ....
  45. doi request reprint Impaired intestinal vitamin B1 (thiamin) uptake in thiamin transporter-2-deficient mice
    Jack C Reidling
    Department of Medical Research, VA Medical Center, Long Beach, California 90822, USA
    Gastroenterology 138:1802-9. 2010
    ..We tested this possibility and examined the role of THTR-2 in uptake of thiamin in the intestine of mice...
  46. ncbi request reprint Molecular mechanisms involved in the adaptive regulation of human intestinal biotin uptake: A study of the hSMVT system
    Jack C Reidling
    Veterans Affairs Medical Center 151, 5901 E 7th St, Long Beach, CA 90822, USA
    Am J Physiol Gastrointest Liver Physiol 292:G275-81. 2007
    ....
  47. ncbi request reprint Comparative analysis of ontogenic changes in renal and intestinal biotin transport in the rat
    Svetlana M Nabokina
    Veterans Affairs Medical Center, Long Beach 90822, USA
    Am J Physiol Renal Physiol 284:F737-42. 2003
    ..In addition, the ontogenic changes observed in the intestinal biotin uptake process involve the entry step of the vitamin at the BBM and appear to be mediated via a transcriptional mechanism(s)...
  48. ncbi request reprint Biotin uptake by human intestinal and liver epithelial cells: role of the SMVT system
    Krishnaswamy Balamurugan
    Veterans Affairs Medical Center 151, Long Beach, CA 90822, USA
    Am J Physiol Gastrointest Liver Physiol 285:G73-7. 2003
    ..In addition, the results provide strong evidence that SMVT is the major (if not the only) biotin uptake system that operates in these cells...
  49. ncbi request reprint A C-terminal region dictates the apical plasma membrane targeting of the human sodium-dependent vitamin C transporter-1 in polarized epithelia
    Veedamali S Subramanian
    Department of Medicine, University of California, Irvine, California 92697, USA
    J Biol Chem 279:27719-28. 2004
    ..Our results provide the first direct resolution of functional hSVCT1 expression at the apical cell surface of polarized epithelia and define an apical targeting signal of relevance to transporters of diverse substrate specificity...
  50. pmc Identification of dynein light chain road block-1 as a novel interaction partner with the human reduced folate carrier
    Balasubramaniem Ashokkumar
    Department of Medical Research, Veterans Affairs Medical Center, Long Beach, California 90822, USA
    Am J Physiol Gastrointest Liver Physiol 297:G480-7. 2009
    ..05) decrease in folate uptake. This study demonstrates for the first time the identification of DYNLRB1 as an interacting protein partner with hRFC. Furthermore, DYNLRB1 appears to influence the function and cell biology of hRFC...
  51. doi request reprint Pyridoxine uptake by colonocytes: a specific and regulated carrier-mediated process
    Zainab M Said
    Department of Medicine and Physiology, University of California, Irvine, California, USA
    Am J Physiol Cell Physiol 294:C1192-7. 2008
    ..These studies demonstrate, for the first time, the functional existence of a specific and regulatable carrier-mediated process for pyridoxine uptake by mammalian colonocytes...
  52. pmc Differentiation-dependent regulation of the intestinal folate uptake process: studies with Caco-2 cells and native mouse intestine
    Veedamali S Subramanian
    Departments of Medicine, University of California, Irvine, California, USA
    Am J Physiol Cell Physiol 295:C828-35. 2008
    ..In addition, the studies suggest the possible involvement (at least in part) of a transcriptional mechanism(s) in this type of regulation of the intestinal folate uptake process...
  53. pmc Chronic alcohol consumption and intestinal thiamin absorption: effects on physiological and molecular parameters of the uptake process
    Sandeep B Subramanya
    Department of Medical Research, VA Medical Center, Long Beach, and Department of Medicine, University of California College of Medicine, Irvine, California, USA
    Am J Physiol Gastrointest Liver Physiol 299:G23-31. 2010
    ..Furthermore, the inhibition is, at least in part, mediated via transcriptional mechanism(s)...
  54. ncbi request reprint Folate uptake in the human intestine: promoter activity and effect of folate deficiency
    Veedamali S Subramanian
    VA Medical Center, Long Beach, California 90822, USA
    J Cell Physiol 196:403-8. 2003
    ..In addition, folate-deficiency was found to up-regulate folate uptake by human intestinal epithelial cells and that this regulation involves activation of hRFC pB...
  55. ncbi request reprint Mechanism and regulation of folate uptake by human pancreatic epithelial MIA PaCa-2 cells
    Svetlana M Nabokina
    Veterans Affairs Medical Center, Long Beach, CA 90822, USA
    Am J Physiol Cell Physiol 287:C142-8. 2004
    ..The results also show the involvement of hRFC in the uptake process and suggest the possible involvement of intracellular cAMP- and PTK-mediated pathways in the regulation of folate uptake...
  56. ncbi request reprint Cloning and functional characterization of a folate transporter from the nematode Caenorhabditis elegans
    Krishnaswamy Balamurugan
    VA Medical Center 151, Long Beach, CA 90822, USA
    Am J Physiol Cell Physiol 293:C670-81. 2007
    ..Thus C. elegans provides a genetically tractable model that can be used to study integrative aspects of the folate uptake process in the context of the whole animal level...
  57. ncbi request reprint Mechanism and regulation of human intestinal niacin uptake
    Svetlana M Nabokina
    Veterans Affairs Healthcare System, Long Beach, California 90822, USA
    Am J Physiol Cell Physiol 289:C97-103. 2005
    ..The results also suggest the possible involvement of a PTK-mediated pathway in the regulation of niacin uptake...
  58. ncbi request reprint Ontogenic regulation of folate transport across rat jejunal brush-border membrane
    Krishnaswamy Balamurugan
    Veterans Affairs Medical Center 151, Long Beach, CA 90822, USA
    Am J Physiol Gastrointest Liver Physiol 285:G1068-73. 2003
    ..These results demonstrate for the first time that folate transport across the intestinal BBM is under ontogenic regulation during early stages of life and that this regulation involves a transcriptional regulatory mechanism(s)...
  59. ncbi request reprint Targeting and intracellular trafficking of clinically relevant hTHTR1 mutations in human cell lines
    Veedamali S Subramanian
    Department of Medicine, University of California, Irvine, CA 92697, USA
    Clin Sci (Lond) 113:93-102. 2007
    ..Our results reveal a spectrum of mutant phenotypes, underlining that TRMA can result from decreased thiamine transport activity underpinned by changes in hTHTR1 expression levels, cellular targeting and/or protein transport activity...
  60. ncbi request reprint Functional role of specific amino acid residues in human thiamine transporter SLC19A2: mutational analysis
    Krishnaswamy Balamurugan
    Veterans Affairs Medical Center, Long Beach, CA 90822, USA
    Am J Physiol Gastrointest Liver Physiol 283:G37-43. 2002
    ..Results also show conserved TM anionic residue of the SLC19A2 protein is critical for its function. Furthermore, native SLC19A2 is glycosylated, but this is not important for its function...
  61. ncbi request reprint Developmental maturation of intestinal and renal thiamin uptake: studies in wild-type and transgenic mice carrying human THTR-1 and 2 promoters
    Jack C Reidling
    VA Medical Center, Long Beach, CA 90822 and University of California College of Medicine, Irvine, California 92697, USA
    J Cell Physiol 206:371-7. 2006
    ....
  62. ncbi request reprint Expression and promoter analysis of SLC19A2 in the human intestine
    Jack C Reidling
    University of California, Irvine, CA 92697, USA
    Biochim Biophys Acta 1561:180-7. 2002
    ..In addition, the results provide the first characterization of the SLC19A2 promoter. These findings raise the possibility that SLC19A2 may play a role in the normal intestinal thiamine absorption process...
  63. ncbi request reprint Regulation of the human biotin transporter hSMVT promoter by KLF-4 and AP-2: confirmation of promoter activity in vivo
    Jack C Reidling
    Veterans Affairs Medical Center, Long Beach, CA 90822, USA
    Am J Physiol Cell Physiol 292:C1305-12. 2007
    ..The results demonstrate, for the first time, the importance of KLF-4 and AP-2 in regulating the activity of the hSMVT promoter in the intestine and provide direct in vivo confirmation of hSMVT promoter activity...
  64. pmc Mechanisms and regulation of vitamin C uptake: studies of the hSVCT systems in human liver epithelial cells
    Jack C Reidling
    Veterans Affairs Medical Center, Long Beach, CA 90822, USA
    Am J Physiol Gastrointest Liver Physiol 295:G1217-27. 2008
    ..These studies are the first to determine the overall ascorbic acid uptake process and relative expression, regulation, and contribution of the hSVCT systems in human liver epithelial cells...
  65. pmc N-Glycosylation is required for Na+-dependent vitamin C transporter functionality
    Veedamali S Subramanian
    Departments of Medicine, Physiology and Biophysics, University of California, Irvine, CA 92697, USA
    Biochem Biophys Res Commun 374:123-7. 2008
    ..N-Glycosylation is therefore essential for vitamin C transporter functionality...
  66. pmc Molecular determinants dictating cell surface expression of the human sodium-dependent vitamin C transporter-2 in human liver cells
    Veedamali S Subramanian
    Department of Medicine, University of California, Irvine, CA, USA
    Am J Physiol Gastrointest Liver Physiol 298:G267-74. 2010
    ....
  67. ncbi request reprint Role of reduced folate carrier in intestinal folate uptake
    Krishnaswamy Balamurugan
    Veterans Affairs Medical Center 151, 5901 E 7th St, Long Beach, CA 90822, USA
    Am J Physiol Cell Physiol 291:C189-93. 2006
    ..These results demonstrate that the RFC system is the major (if not the only) folate uptake system that is functional in intestinal epithelial cells...
  68. ncbi request reprint Characterization of the 5'-regulatory region of the human thiamin transporter SLC19A3: in vitro and in vivo studies
    Svetlana M Nabokina
    Veterans Affairs Medical Center 151, Long Beach, CA 90822, USA
    Am J Physiol Gastrointest Liver Physiol 287:G822-9. 2004
    ..These studies report the first characterization of the SLC19A3 promoter in vitro and in vivo and demonstrate the importance of an SP1 cis-regulatory element in regulating promoter activity of this important human gene...
  69. ncbi request reprint Characterization of the 5' regulatory region of the human sodium-dependent multivitamin transporter, hSMVT
    Sanjit Dey
    Veterans Affairs Medical Center, Los Angeles, CA 90073, USA
    Biochim Biophys Acta 1574:187-92. 2002
    ..These results demonstrate the first molecular characterization of the regulatory region of this important human gene...
  70. ncbi request reprint Adaptive regulation of intestinal thiamin uptake: molecular mechanism using wild-type and transgenic mice carrying hTHTR-1 and -2 promoters
    Jack C Reidling
    Department of Medical Research, VA Medical Center 151, Long Beach, CA 90822, USA
    Am J Physiol Gastrointest Liver Physiol 288:G1127-34. 2005
    ....
  71. pmc Role of cysteine residues in cell surface expression of the human riboflavin transporter-2 (hRFT2) in intestinal epithelial cells
    Veedamali S Subramanian
    Department of Medicine, University of California Medical School, Irvine, USA
    Am J Physiol Gastrointest Liver Physiol 301:G100-9. 2011
    ..These results demonstrate a potential role for specific cysteine residues in the cell surface expression of the hRFT2 in human intestinal epithelial cells...
  72. pmc Effect of chronic kidney disease on the expression of thiamin and folic acid transporters
    Farhan J Bukhari
    Department of Medical Research, VA Medical Center, 5901 East 7th St, Long Beach, CA 90822, USA
    Nephrol Dial Transplant 26:2137-44. 2011
    ..Earlier studies have documented impaired intestinal absorption of several B vitamins in experimental CKD. In this study, we explored the effect of CKD on expression of folate and thiamin transporters in the key organs and tissues...
  73. pmc Association of PDZ-containing protein PDZD11 with the human sodium-dependent multivitamin transporter
    Svetlana M Nabokina
    Department of Medicine, University of California, Irvine, USA
    Am J Physiol Gastrointest Liver Physiol 300:G561-7. 2011
    ..These results demonstrate for the first time that PDZD11 is an interacting partner with hSMVT in intestinal epithelial cells and that this interaction affects hSMVT function and cell biology...
  74. ncbi request reprint TNF-alpha-induced increase in intestinal epithelial tight junction permeability requires NF-kappa B activation
    Thomas Y Ma
    Department of Internal Medicine, University of New Mexico, Albuquerque, NM 87131 0001, USA
    Am J Physiol Gastrointest Liver Physiol 286:G367-76. 2004
    ..The increase in permeability was associated with NF-kappa B-dependent downregulation of ZO-1 protein expression and alteration in junctional localization...
  75. ncbi request reprint Biotin supply affects rates of cell proliferation, biotinylation of carboxylases and histones, and expression of the gene encoding the sodium-dependent multivitamin transporter in JAr choriocarcinoma cells
    Sarah E R H Crisp
    Dept of Nutritional Science and Dietetics, University of Nebraska at Lincoln, 316 Ruth Leverton Hall, Lincoln, NE 68583 0806, USA
    Eur J Nutr 43:23-31. 2004
    ..Placental transfer of nutrients and secretion of hormones is essential for normal fetal development...
  76. pmc Polarized expression of members of the solute carrier SLC19A gene family of water-soluble multivitamin transporters: implications for physiological function
    Michael J Boulware
    Department of Pharmacology, 321 Church Street SE, University of Minnesota Medical School, MN 55455, USA
    Biochem J 376:43-8. 2003
    ..Such polarization decreases functional redundancy between transporter isoforms and allows for independent regulation of thiamine import and export pathways in cells...
  77. ncbi request reprint In vitro and in vivo characterization of the minimal promoter region of the human thiamin transporter SLC19A2
    Jack C Reidling
    Veterans Affairs Medical Center Long Beach and University of California Irvine, USA
    Am J Physiol Cell Physiol 285:C633-41. 2003
    ..The results demonstrate the importance of GKLF, NF-1, and SP-1 in regulating the activity of the SLC19A2 promoter and provide direct in vivo confirmation of promoter activity...
  78. ncbi request reprint Evidence for a carrier-mediated mechanism for thiamine transport to human jejunal basolateral membrane vesicles
    Pradeep K Dudeja
    Department of Medicine, University of Illinois at Chicago, USA
    Dig Dis Sci 48:109-15. 2003
    ..38 +/- 0.35 pmol/mg protein/10 sec). These results indicate the presence of a proton gradient-dependent specialized carrier-mediated exchange mechanism for thiamine transport across the human jejunum basolateral membranes...
  79. ncbi request reprint Mechanism of TNF-{alpha} modulation of Caco-2 intestinal epithelial tight junction barrier: role of myosin light-chain kinase protein expression
    Thomas Y Ma
    Internal Medicine Gastroenterology, MSC10 5550, 1 Univ of New Mexico, Albuquerque, NM 87131 0001, USA
    Am J Physiol Gastrointest Liver Physiol 288:G422-30. 2005
    ....
  80. ncbi request reprint Cell biology of the human thiamine transporter-1 (hTHTR1). Intracellular trafficking and membrane targeting mechanisms
    Veedamali S Subramanian
    Department of Neurobiology and Behavior, University of California, Irvine 92697, USA
    J Biol Chem 278:3976-84. 2003
    ..Taken together, these results correlate hTHTR1 structure with cellular expression profile and reveal a critical dependence on hTHTR1 backbone integrity and microtubule-based trafficking processes for functional expression of hTHTR1...
  81. ncbi request reprint Alternative transcripts of rat slc19a1: defective sorting and inefficient expression of alternative splicing products--an addendum
    Stephanie Schrader
    Pharmacy and Toxicology, Faculty of Veterinary Medicine, An den Tierkliniken 15, University of Leipzig, Institute of Pharmacology, Leipzig, 04103, Germany
    DNA Seq 17:83-6. 2006
    ..Instead, these proteins accumulated in intracellular granules, and were, apparently, degraded. Hence, it is unlikely that these minor splicing forms are directly involved in solute transport across the plasma membrane...

Research Grants24

  1. CHARACTERIZATION OF INTESTINAL ABSORPTION OF VITAMIN B1
    HAMID SAID; Fiscal Year: 2003
    ..abstract_text> ..
  2. Intestinal Biotin Absorption: Physiological, Cellular and Molecular Aspects
    Hamid M Said; Fiscal Year: 2010
    ..Results of these investigations should help in the designing of effective strategies to optimize biotin body levels, especially in conditions associated with biotin deficiency and sub-optimal levels. 1 ..
  3. Human Intestinal Biotin Uptake:Molecular /Cell Mechanisms
    HAMID SAID; Fiscal Year: 2007
    ..This should ultimately assist us in the design of effective strategies to optimize biotin body homeostasis in conditions associated with biotin deficiency and sub-optimal levels. ..
  4. Mechanism/regulation of human intestinal thiamin uptake
    HAMID SAID; Fiscal Year: 2007
    ..This should ultimately assist us in the designing of effective strategies to optimize thiamin body homeostasis in conditions associated with thiamin deficiency and sub-optimal levels. ..
  5. C elegans:a model to study intestinal water-soluble vitamins transport in vivo
    HAMID SAID; Fiscal Year: 2007
    ..This should be of great value in future investigations into the mechanisms and regulation of transport of water-soluble vitamins in the intestine (and other tissues) at the integrated whole animal level in vivo. ..
  6. Mechanisms of Pancreatic Thiamin Uptake:Effect of Alcohol
    HAMID SAID; Fiscal Year: 2009
    ....
  7. Human Intestinal Biotin Uptake: Molecular/Cell Mechanisms
    HAMID SAID; Fiscal Year: 2009
    ..This should ultimately assist us in the design of effective strategies to optimize biotin body homeostasis in conditions associated with biotin deficiency and sub-optimal levels. ..
  8. Mechanisms of Pancreatic Thiamin Uptake:Effect of Alcohol
    Hamid M Said; Fiscal Year: 2010
    ....
  9. INTESTINAL VITAMIN H UPTAKE--MOLECULAR/CELL REGULATION
    HAMID SAID; Fiscal Year: 2004
    ..These results should also contribute toward our understanding of regulation of SMVT function in other tissues that have been shown to express this transport system. ..