CONCLUSION

These results indicate that HGF prevents astrocytic activation and inhibits production of chondroitin sulfate proteoglycans after spinal cord injury in vivo and in vitro. In glial scars mimicking astrocyte cultures, HGF prevented astrocyte activation in a dose-dependent manner. HGF evidently reduced production and deposition of chondroitin sulfate proteoglycans around the lesion. We suggest that inhibition of secretion TGFβ1 and TGFβ2 from activated astrocyte is the mechanism by which HGF prevents the astrocytic activation and production of chondroitin sulfate proteoglycans.

REFERENCE

1. Asher RA, Morgenstern DA, Fidler PS, Adcock KH, Oohira A, Braistead JE, Levine JM, Margolis RU, Rogers JH, Fawcett JW: Neurocan is upregulated in injured brain and in cytokine-treated astrocytes. J Neurosci 20: 2427-2438, 2000

2. Baghdassarian D, Toru-Delbauffe D, Gavaret JM, Pierre M: Effects of transforming growth factor-beta 1 on the extracellular matrix and cytoskeleton of cultured astrocytes. Glia 7: 193-202, 1993

3. Bai X, Ma D, Liu A, Shen X, Wang QJ, Liu Y, Jiang Y: Rheb activates mTOR by antagonizing its endogenous inhibitor, FKBP38. Science 318: 977-980, 2007

4. Border WA, Noble NA: Transforming growth factor beta in tissue fibrosis. N Engl J Med 331: 1286-1292, 1994

5. Bradbury EJ, Moon LD, Popat RJ, King VR, Bennett GS, Patel PN, Fawcett JW, McMahon SB: Chondroitinase ABC promotes functional recovery after spinal cord injury. Nature 416: 636-640, 2002

6. Brahmachari S, Fung YK, Pahan K: Induction of glial fibrillary acidic protein expression in astrocytes by nitric oxide. J Neurosci 26: 4930-4939, 2006

7. Busch SA, Silver J: The role of extracellular matrix in CNS regeneration. Curr Opin Neurobiol 17: 120-127, 2007

8. Buss A, Pech K, Kakulas BA, Martin D, Schoenen J, Noth J, Brook GA: TGF-beta1 and TGF-beta2 expression after traumatic human spinal cord injury. Spinal Cord 46:

364-371, 2008

9. Caggiano AO, Zimber MP, Ganguly A, Blight AR, Gruskin EA: Chondroitinase ABCI improves locomotion and bladder function following contusion injury of the rat spinal cord. J Neurotrauma 22: 226-239, 2005

10. Ebens A, Brose K, Leonardo ED, Hanson MG, Jr., Bladt F, Birchmeier C, Barres BA, Tessier-Lavigne M: Hepatocyte growth factor/scatter factor is an axonal chemoattractant and a neurotrophic factor for spinal motor neurons. Neuron 17:

1157-1172, 1996

11. Faulkner JR, Herrmann JE, Woo MJ, Tansey KE, Doan NB, Sofroniew MV: Reactive astrocytes protect tissue and preserve function after spinal cord injury. J Neurosci 24:

2143-2155, 2004

12. Fitch MT, Doller C, Combs CK, Landreth GE, Silver J: Cellular and molecular mechanisms of glial scarsring and progressive cavitation: in vivo and in vitro analysis of inflammation-induced secondary injury after CNS trauma. J Neurosci 19:

8182-8198, 1999

13. Galtrey CM, Fawcett JW: The role of chondroitin sulfate proteoglycans in regeneration and plasticity in the central nervous system. Brain Res Rev 54: 1-18, 2007

14. Garzotto D, Giacobini P, Crepaldi T, Fasolo A, De Marchis S: Hepatocyte growth factor regulates migration of olfactory interneuron precursors in the rostral migratory stream through Met-Grb2 coupling. J Neurosci 28: 5901-5909, 2008

15. Gherardi E, Sharpe M, Lane K, Sirulnik A, Stoker M: Hepatocyte growth factor/scatter factor (HGF/SF), the c-met receptor and the behaviour of epithelial cells. Symp Soc Exp Biol 47: 163-181, 1993

16. Gomes FC, Sousa Vde O, Romao L: Emerging roles for TGF-beta1 in nervous system development. Int J Dev Neurosci 23: 413-424, 2005

17. Hara K, Maruki Y, Long X, Yoshino K, Oshiro N, Hidayat S, Tokunaga C, Avruch J, Yonezawa K: Raptor, a binding partner of target of rapamycin (TOR), mediates TOR action. Cell 110: 177-189, 2002

18. Hewett SJ, Corbett JA, McDaniel ML, Choi DW: Interferon-gamma and interleukin-1 beta induce nitric oxide formation from primary mouse astrocytes. Neurosci Lett 164:

229-232, 1993

19. Hudgins SN, Levison SW: Ciliary neurotrophic factor stimulates astroglial hypertrophy in vivo and in vitro. Exp Neurol 150: 171-182, 1998

20. John GR, Lee SC, Brosnan CF: Cytokines: powerful regulators of glial cell activation.

Neuroscientist 9: 10-22, 2003

21. Jones LL, Tuszynski MH: Spinal cord injury elicits expression of keratan sulfate proteoglycans by macrophages, reactive microglia, and oligodendrocyte progenitors.

J Neurosci 22: 4611-4624, 2002

22. Jones LL, Margolis RU, Tuszynski MH: The chondroitin sulfate proteoglycans neurocan, brevican, phosphacan, and versican are differentially regulated following spinal cord injury. Exp Neurol 182: 399-411, 2003

23. Kadoyama K, Funakoshi H, Ohya W, Nakamura T: Hepatocyte growth factor (HGF) attenuates gliosis and motoneuronal degeneration in the brainstem motor nuclei of a transgenic mouse model of ALS. Neurosci Res 59: 446-456, 2007

24. Kim TH, Mars WM, Stolz DB, Petersen BE, Michalopoulos GK: Extracellular matrix remodeling at the early stages of liver regeneration in the rat. Hepatology 26: 896-904, 1997

25. Kitamura K, Iwanami A, Nakamura M, Yamane J, Watanabe K, Suzuki Y, Miyazawa D,

Shibata S, Funakoshi H, Miyatake S, Coffin RS, Nakamura T, Toyama Y, Okano H:

Hepatocyte growth factor promotes endogenous repair and functional recovery after spinal cord injury. J Neurosci Res 85: 2332-2342, 2007

26. Kobayashi E, Sasamura H, Mifune M, Shimizu-Hirota R, Kuroda M, Hayashi M, Saruta T: Hepatocyte growth factor regulates proteoglycan synthesis in interstitial fibroblasts. Kidney Int 64: 1179-1188, 2003

27. Krasnoselsky A, Massay MJ, DeFrances MC, Michalopoulos G, Zarnegar R, Ratner N:

Hepatocyte growth factor is a mitogen for Schwann cells and is present in neurofibromas. J Neurosci 14: 7284-7290, 1994

28. Lee BS, Park M, Cha HY, Lee JH: Hepatocyte growth factor induces delayed STAT3 phosphorylation through interleukin-6 expression. Cell Signal 21: 419-427, 2009

29. Levison SW, Hudgins SN, Crawford JL: Ciliary neurotrophic factor stimulates nuclear hypertrophy and increases the GFAP content of cultured astrocytes. Brain Res 803:

189-193, 1998

30. Liu Y: Hepatocyte growth factor in kidney fibrosis: therapeutic potential and mechanisms of action. Am J Physiol Renal Physiol 287: F7-16, 2004

31. Liu Y: Renal fibrosis: new insights into the pathogenesis and therapeutics. Kidney Int 69:

213-217, 2006

32. Liu Y, Yang J: Hepatocyte growth factor: new arsenal in the fights against renal fibrosis?

Kidney Int 70: 238-240, 2006

33. Logan A, Green J, Hunter A, Jackson R, Berry M: Inhibition of glial scarsring in the injured rat brain by a recombinant human monoclonal antibody to transforming growth factor-beta2. Eur J Neurosci 11: 2367-2374, 1999

34. Logan A, Berry M, Gonzalez AM, Frautschy SA, Sporn MB, Baird A: Effects of transforming growth factor beta 1 on scar production in the injured central nervous system of the rat. Eur J Neurosci 6: 355-363, 1994

35. Ma PC, Maulik G, Christensen J, Salgia R: c-Met: structure, functions and potential for therapeutic inhibition. Cancer Metastasis Rev 22: 309-325, 2003

36. Machide M, Kamitori K, Kohsaka S: Hepatocyte growth factor-induced differential activation of phospholipase cgamma 1 and phosphatidylinositol 3-kinase is regulated by tyrosine phosphatase SHP-1 in astrocytes. J Biol Chem 275: 31392-31398, 2000

37. Maina F, Klein R: Hepatocyte growth factor, a versatile signal for developing neurons.

Nat Neurosci 2: 213-217, 1999

38. Matsumoto K, Nakamura T: Hepatocyte growth factor: molecular structure, roles in liver regeneration, and other biological functions. Crit Rev Oncog 3: 27-54, 1992

39. Matsumoto K, Nakamura T: NK4 (HGF-antagonist/angiogenesis inhibitor) in cancer biology and therapeutics. Cancer Sci 94: 321-327, 2003

40. McKeon RJ, Jurynec MJ, Buck CR: The chondroitin sulfate proteoglycans neurocan and phosphacan are expressed by reactive astrocytes in the chronic CNS glial scars. J Neurosci 19: 10778-10788, 1999

41. McKeon RJ, Schreiber RC, Rudge JS, Silver J: Reduction of neurite outgrowth in a model of glial scarsring following CNS injury is correlated with the expression of inhibitory molecules on reactive astrocytes. J Neurosci 11: 3398-3411, 1991

42. Moon LD, Fawcett JW: Reduction in CNS scar formation without concomitant increase in axon regeneration following treatment of adult rat brain with a combination of antibodies to TGFbeta1 and beta2. Eur J Neurosci 14: 1667-1677, 2001

43. Nakamura T, Sakata R, Ueno T, Sata M, Ueno H: Inhibition of transforming growth factor beta prevents progression of liver fibrosis and enhances hepatocyte regeneration in dimethylnitrosamine-treated rats. Hepatology 32: 247-255, 2000

44. Nakamura T, Nishizawa T, Hagiya M, Seki T, Shimonishi M, Sugimura A, Tashiro K,

Shimizu S: Molecular cloning and expression of human hepatocyte growth factor.

Nature 342: 440-443, 1989

45. Ohya W, Funakoshi H, Kurosawa T, Nakamura T: Hepatocyte growth factor (HGF) promotes oligodendrocyte progenitor cell proliferation and inhibits its differentiation during postnatal development in the rat. Brain Res 1147: 51-65, 2007

46. Pekny M, Nilsson M: Astrocyte activation and reactive gliosis. Glia 50: 427-434, 2005

47. Reilly JF, Maher PA, Kumari VG: Regulation of astrocyte GFAP expression by TGF-beta1 and FGF-2. Glia 22: 202-210, 1998

48. Rhodes KE, Fawcett JW: Chondroitin sulphate proteoglycans: preventing plasticity or protecting the CNS? J Anat 204: 33-48, 2004

49. Ribotta MG, Menet V, Privat A: Glial scars and axonal regeneration in the CNS: lessons from GFAP and vimentin transgenic mice. Acta Neurochir Suppl 89: 87-92, 2004

50. Rohl C, Armbrust E, Kolbe K, Lucius R, Maser E, Venz S, Gulden M: Activated microglia modulate astroglial enzymes involved in oxidative and inflammatory stress and increase the resistance of astrocytes to oxidative stress in vitro. Glia 56:

1114-1126, 2008

51. Rolls A, Shechter R, Schwartz M: The bright side of the glial scars in CNS repair. Nat Rev Neurosci 10: 235-241, 2009

52. Sabatini DM: mTOR and cancer: insights into a complex relationship. Nat Rev Cancer 6:

729-734, 2006

53. Sandvig A, Berry M, Barrett LB, Butt A, Logan A: Myelin-, reactive glia-, and scar-derived CNS axon growth inhibitors: expression, receptor signaling, and correlation with axon regeneration. Glia 46: 225-251, 2004

54. Shimamura M, Sato N, Sata M, Wakayama K, Ogihara T, Morishita R: Expression of hepatocyte growth factor and c-Met after spinal cord injury in rats. Brain Res 1151:

188-194, 2007

55. Shimazaki K, Yoshida K, Hirose Y, Ishimori H, Katayama M, Kawase T: Cytokines regulate c-Met expression in cultured astrocytes. Brain Res 962: 105-110, 2003

56. Silver J, Miller JH: Regeneration beyond the glial scars. Nat Rev Neurosci 5: 146-156, 2004

57. Smith GM, Strunz C: Growth factor and cytokine regulation of chondroitin sulfate proteoglycans by astrocytes. Glia 52: 209-218, 2005

58. Tang X, Davies JE, Davies SJ: Changes in distribution, cell associations, and protein expression levels of NG2, neurocan, phosphacan, brevican, versican V2, and tenascin-C during acute to chronic maturation of spinal cord scar tissue. J Neurosci Res 71: 427-444, 2003

59. Tester NJ, Howland DR: Chondroitinase ABC improves basic and skilled locomotion in spinal cord injured cats. Exp Neurol 209: 483-496, 2008

60. Tom VJ, Houle JD: Intraspinal microinjection of chondroitinase ABC following injury promotes axonal regeneration out of a peripheral nerve graft bridge. Exp Neurol 211:

315-319, 2008

61. Wullschleger S, Loewith R, Hall MN: TOR signaling in growth and metabolism. Cell 124: 471-484, 2006

62. Yamamoto Y, Livet J, Pollock RA, Garces A, Arce V, deLapeyriere O, Henderson CE:

Hepatocyte growth factor (HGF/SF) is a muscle-derived survival factor for a subpopulation of embryonic motoneurons. Development 124: 2903-2913, 1997

63. Yan H, Rivkees SA: Hepatocyte growth factor stimulates the proliferation and migration of oligodendrocyte precursor cells. J Neurosci Res 69: 597-606, 2002

64. Yin YL, Chen HL, Kuo HM, He SP: NK3 and NK4 of HGF enhance filamin production

via STAT pathway, but not NK1 and NK2 in human breast cancer cells. Acta Pharmacol Sin 29: 728-735, 2008

65. Yiu G, He Z: Glial inhibition of CNS axon regeneration. Nat Rev Neurosci 7: 617-627, 2006

66. Zhao F, Zhang YF, Liu YG, Zhou JJ, Li ZK, Wu CG, Qi HW: Therapeutic effects of bone marrow-derived mesenchymal stem cells engraftment on bleomycin-induced lung injury in rats. Transplant Proc 40: 1700-1705, 2008a

67. Zhao MZ, Nonoguchi N, Ikeda N, Watanabe T, Furutama D, Miyazawa D, Funakoshi H, Kajimoto Y, Nakamura T, Dezawa M, Shibata MA, Otsuki Y, Coffin RS, Liu WD, Kuroiwa T, Miyatake S: Novel therapeutic strategy for stroke in rats by bone marrow stromal cells and ex vivo HGF gene transfer with HSV-1 vector. J Cereb Blood Flow Metab 26: 1176-1188, 2006

68. Zhao S, Venkatasubbarao K, Lazor JW, Sperry J, Jin C, Cao L, Freeman JW: Inhibition of STAT3 Tyr705 phosphorylation by Smad4 suppresses transforming growth factor beta-mediated invasion and metastasis in pancreatic cancer cells. Cancer Res 68:

4221-4228, 2008b

- 국문요약 -

모방하기 위해 초기 성상(星狀)세포 (primary astrocyte)를 배양하여,