title: [EXPRESSION AND ROLE OF KIP1 UBIQUITYLATION-PROMOTING COMPLEX 2 IN ASTROCYTES AFTER SPINAL CORD INJURY IN RATS].
abstract: OBJECTIVE
  To explore the biological functions of Kip1 ubiquitylation-promoting complex 2 (KPC2) in the repair process of spinal cord injury (SCI) by studying the expression and cellular localization of KPC2 in rat SCI models.
  
  
  METHODS
  Fifty-six adult Sprague-Dawley rats were randomly divided into 2 groups: in the control group (n = 7), simple T9 laminectomy was performed; in the experimental group (n = 49), the SCI model was established at T9, 7 rats were used to detect follow indexs at 6 hours, 12 hours, 1 day, 3 days, 5 days, 7 days, and 14 days after SC. Western blot analysis was used to detect the protein expressions of P27kip1, KPC2, CyclinA and proliferating cell nuclear antigen (PCNA) after SCI. Immunohistochemistry was used to observed the cellular localization of KPC2 after SCI, double-labeling immunofluorescence staining to observe the co-localization of KPC2 with neuronal nuclei (NeuN), glial fibrillary acidic protein (GFAP) and PCNA. In vitro astrocytes proliferation model was used to further validate these results, Western blot to detect KPC2, p27kip1, and PCNA expressions. The interaction of p27kip1, KPC1, and KPC2 in cell proliferation was analyzed by co-immunoprecipitation.
  
  
  RESULTS
  The Western blot analysis showed a significant down-regulation of p27kip1 and a concomitant up-regulation of KPC2, CyclinA, and PCNA after SC. Immunohistochemistry staining revealed a wide distribution of KPC2 positive signals in the gray matter and white matter of the spinal cord. The number of KPC2 positive cells in the experimental group was significantly higher than that in the control group (t = 10.982, P = 0.000). Double-labeling immunofluorescence staining revealed the number of KPC2/NeuN co-expression cells in the gray matter of spinal cord was (0.43 ± 0.53)/visual field in the control group and (0.57 ± 0.53)/visual field in the experimental group, showing no significant difference (t = 0.548, P = 0.604); in the white matter of spinal cord, the number of KPC2/PCNA co-expression cells was (3.86 ± 0.90)/visual field in the control group and (0.71 ± 0.49)/visual field in the experimental group, showing significant difference (t = 7.778, P = 0.000). And then, the number of KPC2/PCNA co-expression cells were (0.57 ± 0.53)/visual field in the control group and (5.57 ± 1.13)/visual field in the experimental group, showing significant difference (t = 8.101, P = 0.000). Concomitantly, there was a similar kinetic in proliferating astrocytes in vitro. The Western blot analysis showed a significant down-regulation of p27kip1 and a concomitant up-regulation of KPC2 and PCNA after serum stimulated. Co-immunoprecipitation demonstrated increased interactions between p27kip1, KPC1, and KPC2 after stimulation.
  
  
  CONCLUSIONS
  The up-regulated expression of KPC2 after SCI is related to the down-regulation of p27kip1, this event may be involved in the proliferation of astrocytes after SCI.
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.forename: Fan
authors.initials: F
authors.lastname: Liu
authors.forename: Jianwei
authors.initials: J
authors.lastname: Zhu
authors.forename: Lifan
authors.initials: L
authors.lastname: Zhu
authors.forename: Fugui
authors.initials: F
authors.lastname: Jiang
mesh_terms: D000818:Animals; D001253:Astrocytes; D049109:Cell Proliferation; D015536:Down-Regulation; D005904:Glial Fibrillary Acidic Protein; D018809:Proliferating Cell Nuclear Antigen; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000473:pathology; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D015854:Up-Regulation
chemical_list: D005904:Glial Fibrillary Acidic Protein; D018809:Proliferating Cell Nuclear Antigen; C558223:Ubac1 protein, rat; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases