Journal of Molecular Neuroscience

, Volume 31, Issue 2, pp 171–181 | Cite as

Urocortin trafficking in cerebral microvessel endothelial cells

  • Hong Tu
  • Abba J. Kastin
  • Christian Bjorbaek
  • Weihong Pan
Original Article


Urocortin, a potent peptide inhibitor of feeding behavior, can enter the brain from blood by leptin-facilitated permeation across the blood-brain barrier. Here, we show in cultured RBE4 cerebral microvessel endothelial cells that urocortin endocytosis is increased by leptin in a time- and dose-dependent manner. Fluorescently labeled urocortin (Alexa488-urocortin) shows vesicular trafficking localized in early endosomes at 1 min and the Golgi complex at 20 min. The endocytosis at 20 min was increased by 10 μg/mL, but not 2 μg/mL, of leptin. The facilitating effect of leptin at the dose of 10 μg/mL was seen at 20 and 30 min but not at 10 min. This increase could be abolished by excess unlabeled urocortin in radio-tracer uptake studies, indicating selective rather than nonsaturable entry. The specificity of the effect was further supported by the lack of changes in γ-glutamyl transpeptidase activity and endothelial nitric oxide synthase upon stimulation by high doses of leptin and urocortin. Leptin did not affect the level of expression of the urocortin corticotropin-releasing hormone receptor (CRHR) after 30 min of treatment but appeared to slow the turnover of CRHRs induced by urocortin. In MDCK cells overexpressing CRHR2, leptin facilitated urocortin uptake, whereas ObRa coexpression did not exert an additional effect. Thus, urocortin endocytosis is a saturable process leading to vesicular intracellular transport that can be enhanced by cell-surface leptin.

Index Entries

Urocortin leptin blood-brain barrier transport endothelial cells 


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  1. Asakawa, A., Inui, A., Ueno, N., Makino, S., Fujino, M. A., and Kasuga W. (1999) Urocrotin reduces food intake and gastric emptying in lean and ob/ob obese mice. Gastroenterology 116, 1287–1292.PubMedCrossRefGoogle Scholar
  2. Banks, W. A. (2003) Is obesity a disease of the blood-brain barrier? Physiological, pathological, and evolutionary considerations. Curr. Pharm. Design 9, 801–809.CrossRefGoogle Scholar
  3. Banks, W. A., Altmann J., Sapolsky R. M., Phllips-Conroy J. E., and Morley J. E. (2003) Serum leptin levels as a marker for a Syndrome X-like condition in wild baboons. J. Clin. Endocrinol. Metab. 88, 1234–1240.PubMedCrossRefGoogle Scholar
  4. Banks W. A. and Farrell C. L. (2003c) Impaired transport of leptin across the blood-brain barrier in obesity is acquired and reversible. Am. J. Physiol. 285, E10-E15.Google Scholar
  5. Banks W. A., Clever C. M., and Farrell C. L. (2000) Partial saturation and regional variation in the blood-to-brain transport of leptin in normal weight mice. Am. J. Physiol. 278, E1158-E1165.Google Scholar
  6. Banks W. A., Kastin A. J., Huang W., Jaspan J. B., and Maness L. M. (1996) Leptin enters the brain by a saturable system independent of insulin. Peptides 17, 305–311.PubMedCrossRefGoogle Scholar
  7. Childs G. V., Morell J. L., Niendorf A., and Aguilera G. (1986) Cytochemical studies of corticotropin-releasing factor (Crf) receptors in anterior lobe corticotropesbinding, glucocorticoid regulation, and endocytosis of [biotinyl-Ser1]Crf. Endocrinology 119, 2129–2142.PubMedCrossRefGoogle Scholar
  8. Etienne, S., Adamson, P., Greenwood J., Strosberg A. D., Cazaubon S., and Couraud P. O. (1998) ICAM-1 signaling pathways associated with Rho activation in microvascular brain endothelial cells. J. Immunol. 161, 5755–5761.PubMedGoogle Scholar
  9. Halaas J. L., Gajiwala K. S., Maffei M., Cohen S. L., Chait B. T., Rabinowitz D., et al. (1995) Weight-reducing effects of the plasma protein encoded by the obese gene. Science 269, 543–546.PubMedCrossRefGoogle Scholar
  10. Hope P. J., Turnbull H., Farr S., Morley J. E., Rice K. C., Chrousos G. P., et al. (2000) Peripheral administration of CRF and urocortin: effects on food intake and the HPA axis in the marsupial Sminthopis crassicaudata. Peptides 21, 669–677.PubMedCrossRefGoogle Scholar
  11. Kastin A. J., Akerstrom V., and Pan W. (2000) Activation of urocortin transport into brain by leptin. Peptides 21, 1811–1817.PubMedCrossRefGoogle Scholar
  12. Kastin A. J. and Pan W. (2006) Intranasal leptin: bloodbrain barrier bypass (BBBB) for obesity. Endocrinology 147, 2086–2087.PubMedCrossRefGoogle Scholar
  13. Kastin A. J., Pan W. H., Akerstrom V., Hackler L., Wang C. F., and Kotz C. M. (2002) Novelpeptide-peptide cooperation may transform feeding behavior. Peptides 23, 2189–2196.PubMedCrossRefGoogle Scholar
  14. Kastin A. J., Pan W., Maness L. M., Koletsky R. J., and Ernsberger P. (1999) Decreased transport of leptin across the blood-brain barrier in rats lacking the short form of the leptin receptor. Peptides 20, 1449–1453.PubMedCrossRefGoogle Scholar
  15. Maness L. M., Banks W. A., and Kastin A. J. (2000) Persistence of blood-to-brain transport of leptin in obese leptin-deficient and leptin receptor-deficient mice. Brain Res., 873, 165–167.PubMedCrossRefGoogle Scholar
  16. Oki Y., Iwabuchi M., Masuzawa M., Watanabe F., Ozawa M., Iino K., et al. (1998) Distribution and concentration of urocortin, and effect of adrenalectomy on its content in rat hypothalamus. Life Sci. 62, 807–812.PubMedCrossRefGoogle Scholar
  17. Oki Y. and Sasano H. (2004) Localization and physiological roles of urocortin. Peptides 25, 1745–1749.PubMedCrossRefGoogle Scholar
  18. Pan W., Akerstrom V., Zhang J., Pejovic V., and Kastin A. J. (2004) Modulation of feeding-related peptide/protein signals by the blood-brain barrier. J. Neurochem. 90, 455–461.PubMedCrossRefGoogle Scholar
  19. Pan W., Yu, Y., Cain C. M., Nyberg F., Couraud P.-O., and Kastin A. J. (2005) Permeation of growth hormone across the blood-brain barrier. Endocrinology 146, 4898–4904.PubMedCrossRefGoogle Scholar
  20. Vaughan J., Donaldson C., Bittencourt J., Perrin, M. H., Lewis K., Sutton S., et al. (1995) Urocortin, a mammalian neuropeptide related to fish urotensin I and to corticotropin-releasing factor. Nature 378, 287–292.PubMedCrossRefGoogle Scholar
  21. Wang L., Martinez V., Rivier J. E., and Tache Y. (2001) Peripheralurocortin inhibits gastric emptying and food intake in mice: differential role of CRF receptor 2. Am. J. Physiol. 281, R1401-R1410.Google Scholar
  22. Yu C., Kastin A. J., Ding Y., and Pan W. (2007) Gamma glutamyl transpeptidase is a dynamic indicator of endothelial response to stroke. Exp. Neurol. 203, 116–122.PubMedCrossRefGoogle Scholar
  23. Zhang J. V., Ren P.-G., Avsian-Kretchmer O., Luo, C.-W., Rauch R., Klein C., and Hsueh A. J. W. (2005) Obestatin, a peptide encoded by the ghrelin gene, opposes ghrelin's effects on food intake. Science 310, 996–999.PubMedCrossRefGoogle Scholar

Copyright information

© Humana Press Inc. 2007

Authors and Affiliations

  • Hong Tu
    • 1
    • 2
  • Abba J. Kastin
    • 1
  • Christian Bjorbaek
    • 3
  • Weihong Pan
    • 1
  1. 1.Pennington Biomedical Research CenterBaton Rouge
  2. 2.Shanghai Cancer InstituteJiao-Tong UniversityShanghaiChina
  3. 3.Harvard Medical SchoolBoston

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