Expression of mitogen-activated protein kinase family in rat renal development.
BACKGROUND
Among mitogen-activated protein kinase (MAPK) family members, extracellular signal-regulated kinase (ERK) promotes proliferation or differentiation, whereas c-Jun N-terminal kinase (JNK) and p38 MAPK (p38) are thought to inhibit cell growth and induce apoptosis. MAPK phosphatase-1 (MKP-1) inactivates and modulates MAPKs. During renal development, large scale proliferation and apoptosis occur. We investigated the temporal and spatial expression patterns of MAPKs and MKP-1 in rat kidney during development.


METHODS
Western blot analysis and immunohistochemistry were performed in the developing and mature kidney of the rat.


RESULTS
The expression of ERK, p38, and MKP-1 were high in developing kidney. On the other hand, JNK was abundantly expressed in adult kidney. Active forms of ERK, p38, and JNK correlated with the protein expression levels. Immunohistochemical studies revealed that ERK was strongly expressed by blastema cells, mesenchymal cells, and ureteric bud tips in nephrogenic zone of embryonic kidney. In neonatal kidney, ERK was more abundant in the deep cortex and the medulla corresponding to tubule maturation. p38 and MKP-1 were detected uniformly in mesenchymal cells, mesangial cells, and ureteric bud epithelia of fetal kidney without an obvious correlation with the occurrence of apoptosis. JNK was expressed by tubular cells and podocytes of adult kidney.


CONCLUSIONS
ERK, p38, and MKP-1 are strongly expressed in developing kidney, and JNK is detected predominantly in adult kidney. Both the temporal and spatial expression of ERK coincides with the maturation of the kidney.
Omori
S
S
Department of Pediatrics and Diagnostic Pathology, Keio University School of Medicine, Tokyo, Japan.
Hida
M
M
Ishikura
K
K
Kuramochi
S
S
Awazu
M
M
D000367:Age Factors; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D018797:Cell Cycle Proteins; D054638:Dual Specificity Phosphatase 1; D005260:Female; D017874:Immediate-Early Proteins / Q000032:analysis / Q000096:biosynthesis; D015151:Immunoblotting; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D048031:JNK Mitogen-Activated Protein Kinases; D007668:Kidney / Q000196:embryology* / Q000201:enzymology*; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases / Q000032:analysis / Q000096:biosynthesis; D020928:Mitogen-Activated Protein Kinases / Q000032:analysis / Q000096:biosynthesis*; D010749:Phosphoprotein Phosphatases; D011247:Pregnancy; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis / Q000096:biosynthesis; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D048051:p38 Mitogen-Activated Protein Kinases
D018797:Cell Cycle Proteins; D017874:Immediate-Early Proteins; D018809:Proliferating Cell Nuclear Antigen; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; C517021:Dusp1 protein, rat; D017027:Protein Tyrosine Phosphatases