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Expression of mitogen-activated protein kinase family in rat renal development
1Department of Pediatrics and Diagnostic Pathology, Keio University School of Medicine, Tokyo, Japan.
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.
Insights
Extracellular signal-regulated kinase (ERK), p38 MAPK (p38), and MAPK phosphatase-1 (MKP-1) are highly expressed in developing rat kidneys, while c-Jun N-terminal kinase (JNK) is prominent in adult kidneys, revealing distinct roles in renal development and maturation.
Area of Science:
- Molecular Biology
- Developmental Biology
- Renal Physiology
Background:
- Mitogen-activated protein kinases (MAPKs) regulate cell processes; ERK promotes growth, while JNK and p38 inhibit it and induce apoptosis.
- MAPK phosphatase-1 (MKP-1) modulates MAPK activity.
- Kidney development involves significant cell proliferation and apoptosis.
Purpose of the Study:
- To investigate the temporal and spatial expression patterns of ERK, JNK, p38, and MKP-1 during rat kidney development.
- To understand the roles of these MAPKs and MKP-1 in renal morphogenesis.
Main Methods:
- Western blot analysis was used to quantify protein levels in developing and mature rat kidneys.
- Immunohistochemistry was employed to determine the cellular localization of MAPKs and MKP-1.
Main Results:
- ERK, p38, and MKP-1 expression was high in developing kidneys; JNK was abundant in adult kidneys.
- Active MAPK forms correlated with protein expression.
- ERK localized to key developing kidney structures like blastema cells and ureteric bud tips, with expression shifting during maturation.
Conclusions:
- ERK, p38, and MKP-1 are significantly expressed during kidney development.
- JNK expression is predominantly observed in the mature kidney.
- ERK's expression pattern aligns with kidney maturation processes.