Increased syndecan expression by pleiotrophin and FGF receptor-expressing astrocytes in injured brain tissue.
Syndecan-1, -2, -3, and -4 are heparan sulfate proteoglycans that are differentially expressed during development and wound repair. To determine whether syndecans are also involved in brain injury, we examined the expression of syndecan core proteins genes in cryo-injured mouse brain, using in situ hybridization. All syndecan mRNA transcripts were similarly expressed in the region surrounding the necrotic tissue, exhibiting peak levels at day 7 after injury. Comparison with cellular markers showed that reactive astrocytes were the primary source of syndecans. Syndecans serve as co-receptors for fibroblast growth factor (FGF) and as a reservoir for another heparin-binding growth factor, pleiotrophin (PTN, or heparin-binding growth-associated molecule. In our model, FGF receptor1 (FGFR1) and PTN mRNA levels were upregulated in reactive astrocytes. The distribution patterns of FGFR1 and PTN overlapped considerably with those of syndecan-1 and -3 mRNAs, respectively. These results suggest that syndecans are expressed primarily in reactive astrocytes, and may provide a supportive environment for regenerating axons in concert with heparin-binding growth factors (e.g., FGF and PTN) in the injured brain.
Iseki
Ken
K
Department of Cell Science, Institute of Biomedical Sciences, Fukushima, Japan. ken@fmu.ac.jp
Hagino
Seita
S
Mori
Tetsuji
T
Zhang
Yuxiang
Y
Yokoya
Sachihiko
S
Takaki
Hiromi
H
Tase
Choichiro
C
Murakawa
Masahiro
M
Wanaka
Akio
A
D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D001930:Brain Injuries / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008813:Mice, Inbred ICR; D011509:Proteoglycans / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D020794:Receptor Protein-Tyrosine Kinases / Q000096:biosynthesis* / Q000235:genetics; D051496:Receptor, Fibroblast Growth Factor, Type 1; D017468:Receptors, Fibroblast Growth Factor / Q000096:biosynthesis* / Q000235:genetics; D053668:Syndecan-1; D053667:Syndecans; D015854:Up-Regulation / Q000235:genetics
D002352:Carrier Proteins; D016207:Cytokines; D008562:Membrane Glycoproteins; D011509:Proteoglycans; D012333:RNA, Messenger; D017468:Receptors, Fibroblast Growth Factor; C508242:Sdc1 protein, mouse; D053668:Syndecan-1; D053667:Syndecans; C066845:pleiotrophin; C496349:Fgfr1 protein, mouse; D020794:Receptor Protein-Tyrosine Kinases; D051496:Receptor, Fibroblast Growth Factor, Type 1