Jiexia Quan

Cobalt chloride induces neurite outgrowth in rat pheochromocytoma PC-12 cells through regulation of endothelin-2/vasoactive intestinal contractor

We investigated whether endothelin‐2/vasoactive intestinal contractor (ET‐2/VIC) gene expression, upregulated by hypoxia in cancer cells, was associated with differentiation in neuronal cells. RT‐PCR analysis, morphological observations, and immunostaining revealed that CoCl2, a hypoxic mimetic agent, at 200 μM increased expression of the ET‐2/VIC gene, decreased expression of the ET‐1 gene, and induced neurite outgrowth in PC‐12 rat pheochromocytoma cells. These effects induced by 200 μM CoCl2 were completely inhibited by the antioxidant N‐acetyl cysteine at 20 mM. In addition, CoCl2 increased the level of intracellular reactive oxygen species (ROS) at an early stage. Furthermore, interleukin (IL)‐6 gene expression was upregulated upon the differentiation induced by CoCl2. These results suggest that expression of ET‐2/VIC and ET‐1 mediated by ROS may be associated with neuronal differentiation through the regulation of IL‐6. When the cells were treated with 500 μM CoCl2 for 24 hr, however, ET‐2/VIC gene expression disappeared, IL‐6 gene expression was downregulated, and necrosis was subsequently induced in the PC‐12 cells.

Increased gene expression and production of murine endothelin receptors after birth

We developed the real-time PCR quantification of endothelin-A (ET-A) and endothelin-B (ET-B) receptor genes and present their relative expression levels in various adult tissues and during development in mouse using the 2(-Delta Delta C(T)) method. ET-A and ET-B receptors were detected in all tissues examined. Gene expression of ET-A and ET-B receptors increases during the later stages of embryonic development in lung, heart, liver, kidney, and skin and reaches a maximum on the first one or two days after birth. The results, in agreement with our data on endothelin (ET) ligands, suggest that the ET system may be involved in the emergence and maintenance of functions vital after birth in these organs. These findings were corroborated through observation of the correlation between the gene expression and (poly)peptide production of the ET system in normal skin before and after parturition.

cDNA cloning and sequence analysis of preproendothelin-1 (PPET-1) from salmon, Oncorhynchus keta.

The presence of endothelin (ET)-like immunoreactivity and the cardiovascular effects of mammalian ET-1 in fish have been reported. To identify ET-related peptides in fish, we screened the cDNA library of the salmon (Oncorhynchus keta) stomach by means of rapid amplification of cDNA ends, and we cloned cDNAs encoding an ET-related peptide. The salmon ET-related sequence of 21 amino acids is identical to the trout ET-1 peptide recently purified from kidney specimens of Oncorhynchus mykiss. The deduced amino acid sequence of salmon pre-proET-1 (PPET-1) comprises 244 amino acids, including a putative signal sequence and mature ET-1, as well as big ET-1 and ET-1-like sequences. This precursor, the first reported PPET-1 sequence for Salmoniformes, Teleostei, has low homology with the sequences of human, mouse, frog (Xenopus laevis), and zebrafish (Danio rerio) PPET-1 (26%, 29%, 24%, and 39%, respectively).

Real-time polymerase chain reaction quantification of gene expression levels of murine endothelin-A and endothelin-B receptors: gene expression profiles by the standard curve method.

A rapid analysis method for murine endothelin-A (ETA) and endothelin-B (ETB) receptor gene expression levels was established using real-time quantitative reverse transcriptasepolymerase chain reaction. We designed primer pairs and TaqMan probes specific for the two cDNAs and available for mouse and rat systems. The standard curve method was used to examine relative expression. The gene expression levels of ETA and ETB were estimated as gene expression rates by normalizing to the expression of the housekeeping gene glyceraldehyde-3-phosphate dehydrogenase. To examine the reproducibility of this assay system, we calculated the intra-assay and interassay coefficients of variation of the gene expression rate and found that a greater than 1.6-fold increase in relative gene expression is detectable as a significant change. ETA and ETB receptor gene expression was found in all 16 organs of mouse and rat examined, and high levels of expression were observed in the lung, uterus, ovary, intestine, and cerebellum. The gene expression patterns essentially agreed with those determined by RNase protection assay, Northern blot, and conventional endpoint polymerase chain reaction. These results show that this new rapid, sensitive, and semi-automated method is accurate, quantitative, and reproducible. This method is also useful for examining regulation of hormone receptor gene expression under physiological conditions in organs.

cDNA cloning and sequence analysis of Xenopus laevis preproendothelin-1

Endothelin (ET)-like immunoreactivity has been observed not only in mammals, but also in amphibians. The biological actions of ET are similar in amphibians and mammals, and amphibian ET-related receptors have been cloned and characterized. The cDNA sequences of mature and precursor forms of ET-related peptides, however, have not been reported in any amphibian until now. To identify the ET-related peptides, we screened the Xenopus laevis intestine cDNA library using the rapid amplification of cDNA ends method and cloned cDNAs encoding preproendothelin-1. The deduced amino acid sequence of X. laevis preproendothelin-1 comprises 223 amino acids, including a putative signal sequence of 19 amino acids, a mature ET-1 of 21 amino acids, as well as big ET-1 and ET-1-like sequences. X. laevis ET-1 is identical to mammalian ET-1 as well as ET-1 peptide, recently purified from the stomach of the European green frog, Rana ridibunda. This is the first report describing the cDNA encoding preproendothelin-1 in an amphibian species.

Structure of the precursor of Xenopus laevis endothelin-3 and phylogenetic analysis.

Endothelin (ET)-related receptors homologous to mammalian receptors have been cloned from Xenopus laevis, indicating that ET-related ligands may be present in this species. Here we cloned cDNAs encoding preproendothelin-3 (PPET-3) from the X. laevis intestinal cDNA library. X. laevis ET-3 cDNA encodes 201 amino acids, including a 20-amino-acid putative signal sequence, as well as mature ET-3, big ET-3, and ET-3-like sequences. X. laevis ET-3 differs by one amino acid from mammalian ET-3, and is identical to frog ET-3 recently purified from Rana ridibunda. This sequence together with other published PPET sequences were used to analyze the phylogenetic relationship among all ET family genes. This is the first report of the cDNA encoding the precursor protein of ET-3 in a non-mammalian species.