Time-dependent expression and distribution of Egr-1 during skeletal muscle wound healing in rats.
Recent studies have shown that early growth response factor-1 (Egr-1) plays an important role in regulation of inflammation and tissue repair, but little is known about its expression after trauma to skeletal muscles. A preliminary study on time-dependent expression and distribution of Egr-1 was performed by immunohistochemistry, immunofluorescence and Western blotting during skeletal muscle wound healing in rats. An animal model of skeletal muscle contusion was established in 45 Sprague-Dawley male rats. Samples were taken at 6 h, 12 h, 1 day, 3 days, 5 days, 7 days, 10 days, 14 days and 21 days post-injury, respectively (5 rats in each posttraumatic interval). 5 rats were employed as control. In the uninjured controls, Egr-1 positive staining was observed in the sarcoplasm and nuclei of normal myofibers. In wounded specimens, a small number of polymorphonuclear cells (PMNs), a number of mononuclear cells (MNCs), fibroblastic cells (FBCs) and regenerated multinucleated myotubes showed positive reaction for Egr-1 in contused zones. By morphometric analysis, an increase in Egr-1 expression was verified at inflammatory phase after contusion, which reached a peak in the regenerated phase overlapping with the fibrotic phase during skeletal muscle wound healing. The expression tendency was further confirmed by Western blotting assay. By immunofluorescent staining for co-localization, the Egr-1-positive MNCs and FBCs in wounds were identified as macrophages and myofibroblasts. The results demonstrate that the expression of Egr-1 is up-regulated and temporally distributed in certain cell types after trauma to skeletal muscles, which may be closely involved in inflammatory response, fibrotic repair and muscle regeneration during skeletal muscle wound healing.
Department of Forensic Medicine, School of Basic Medical Science, Wenzhou Medical College, Higher Education District, Wenzhou, Zhejiang Province, People's Republic of China. yyfan998@yahoo.com
Yan-Yan
YY
Fan
Guang-Hua
GH
Ye
Ke-Zhi
KZ
Lin
Lin-Sheng
LS
Yu
Shu-Zhen
SZ
Wu
Miao-Wu
MW
Dong
Jun-Ge
JG
Han
Xiang-Ping
XP
Feng
Xing-Biao
XB
Li
D000818:Animals; D004195:Disease Models, Animal; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries* / Q000378:metabolism*; D021381:Protein Transport; D051381:Rats; D013997:Time Factors; D014945:Wound Healing / Q000235:genetics
D051766:Early Growth Response Protein 1