Differential gene expression and regulation of type-1 angiotensin II receptor subtypes in the rat.

A simplified and sensitive method for measuring expression levels of type-1 angiotensin II (AT1) receptor subtypes, AT1A and AT1B, was established. The two receptor cDNAs were co-amplified and measured by polymerase chain reaction using primers based on the corresponding receptor subtype genes. Both AT1A and AT1B mRNAs were widely expressed in the rat tissues including adrenal gland, kidney, heart, aorta, lung, liver, testis, pituitary gland, cerebrum and cerebellum. AT1A mRNA was predominantly expressed in the rat tissues examined except adrenal gland and pituitary gland where AT1B mRNA was predominantly expressed. Sodium depletion did not change mRNA levels of AT1A and AT1B in the all tissues. However, both AT1A and AT1B mRNA levels in the heart and aorta were down-regulated by treatment with AT1 specific antagonist, TCV 116. In contrast, AT1B mRNA in the adrenal gland was mainly reduced by the treatment. These results suggest that the expression level of AT1B mRNA in the adrenal gland depends on the activity of the renin-angiotensin-aldosterone system (RAAS) and both receptor subtypes mediate contraction and hypertrophy of the smooth and cardiac muscles via the RAAS.     

Molecular cloning, sequence analysis and expression of a cDNA encoding human type-1 angiotensin II receptor.

We isolated a cDNA encoding type-1 angiotensin II receptor from a human liver cDNA library. The cDNA had an open reading frame encoding a protein of 359 amino acid residues with a relative Mr of 41,060. The deduced amino acid sequence of the human angiotensin II (Ang II) receptor was 95.3% and 94.2% identical to those of bovine and rat type-1 Ang II receptors, respectively, and had a significant similarity with the G protein-coupled receptor. The rank order of the binding to the receptor expressed in COS-7 cells was Ang II greater than Ang III greater than Ang I. The expression of the Ang II receptor mRNA was detected in human liver, lung, adrenal and adrenocortical adenomas but not in adrenomedullary tumor, pheochromocytoma, by Northern blot analysis.     

Rat corticotropin-releasing hormone gene: sequence and tissue-specific expression

The rat corticotropin releasing hormone (CRH) gene has been isolated and characterized by DNA sequence analysis. The gene exhibits a structural organization similar to that of the human CRH gene. The nucleotide sequence encoding the entire rat CRH precursor is located on the second exon, while exon I encodes the 5'-untranslated region of the mRNA. Analysis of the nucleotide sequence homology between the human and rat CRH genes reveals several highly conserved regions including the CRH peptide-encoding sequence and the 5'-flanking sequence. RNA blot analysis demonstrates that CRH mRNA can be observed in numerous regions of the rat brain as well as the spinal cord, adrenal gland, pituitary, and testis.     

Posttranscriptional regulation of angiotensin II type 1 receptor expression by glyceraldehyde 3-phosphate dehydrogenase

Regulation of angiotensin II type 1 receptor (AT1R) has a pathophysiological role in hypertension, atherosclerosis and heart failure. We started from an observation that the 3′-untranslated region (3′-UTR) of AT1R mRNA suppressed AT1R translation. Using affinity purification for the separation of 3′-UTR-binding proteins and mass spectrometry for their identification, we describe glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as an AT1R 3′-UTR-binding protein. RNA electrophoretic mobility shift analysis with purified GAPDH further demonstrated a direct interaction with the 3′-UTR while GAPDH immunoprecipitation confirmed this interaction with endogenous AT1R mRNA. GAPDH-binding site was mapped to 1–100 of 3′-UTR. GAPDH-bound target mRNAs were identified by expression array hybridization. Analysis of secondary structures shared among GAPDH targets led to the identification of a RNA motif rich in adenines and uracils. Silencing of GAPDH increased the expression of both endogenous and transfected AT1R. Similarly, a decrease in GAPDH expression by H₂O₂ led to an increased level of AT1R expression. Consistent with GAPDH having a central role in H₂O₂-mediated AT1R regulation, both the deletion of GAPDH-binding site and GAPDH overexpression attenuated the effect of H₂O₂ on AT1R mRNA. Taken together, GAPDH is a translational suppressor of AT1R and mediates the effect of H₂O₂ on AT1R mRNA.     

Rat immunoglobulin delta heavy chain gene: nucleotide sequence derived from cloned cDNA

Rat immunoglobulin δ heavy-chain mRNA has been isolated. RNA blot analysis revealed that this mRNA with a length of 1.8 kb encodes for the secreted form of IgD. The corresponding cDNA was cloned in plasmid pBR322 and its sequence was determined. The hybrid plasmid contains a 775-bp insert comprising a partial Cδ₁ sequence and complete CδH, Cδ3, CδDC and 3' untranslated sequences. Rat and mouse IgD amino acid sequences show striking homology in Cδ3 and CδDC regions.     

cDNA sequence and heterologous expression of the human neurokinin-3 receptor.

Functional cDNA clones encoding the human neurokinin-3 receptor were isolated from human brain mRNA. The cloned human neurokinin-3 receptor was expressed in COS cells and Xenopus oocytes, where peptide binding affinity and intracellular effector activation were determined. Neurokinin B is the most potent agonist, followed by eledoisin, substance K and substance P. The binding affinities of these peptides at the human neurokinin-3 receptor differ quantitatively from the rat receptor, implying a functional consequence of the sequence divergence between the two species. Heterologous expression in oocytes revealed that, unlike the neurokinin-1 receptor, the efficacy of ion channel activation mediated by the neurokinin-3 receptor does not approximate the binding affinity. The heterologous expression of the human neurokinin-3 receptor will facilitate further investigation into its biochemical functions.     

促性腺激素释放激素受体及其基因表达调控

促性腺激素释放激素（ＧｎＲＨ,ＬＨＲＨ）在体内的重要功能是由ＧｎＲＨ受体介导的。ＧｎＲＨ受体是近年神经分内分泌和生殖生物学研究的热点之一,本文从ＧｎＲＨ受体的分子结构,ＧｎＲＨ受体基因表达调控,ＧｎＲＨ受体分布及表达,调节ＲｎＲＨ受体的因素以及ＧｎＲＨ受体介导的细胞信号转导等几个方面对ＧｎＲＨ受体近年来的研究进展进行了综述,对ＧｎＲＨ受体的研究,将有助于人们进一步了解ＧｎＲＨ受体在生殖调节和恶性肿     

cDNA sequence and expression of a phosphoenolpyruvate carboxylase gene from soybean

A full-length cDNA encoding a subunit of phosphoenolpyruvate carboxylase (PEPC) was isolated from a developing seed expression library of the C₃ plant Glycine max. The corresponding mRNA is present at similar levels in leaf, stem, root and developing seed. Two potential start codons exist, and the activity of protein initiated from the first such codon could be subject to regulation by protein kinase. Sequence comparison shows a similar upstream start codon in the case of the Ppc2 gene from Mesembryanthemum crystallinum, previously assumed to lack the sequences necessary for phosphorylation. The soybean encoded protein tends to resemble other C₃-type PEPC proteins more closely than those implicated in C₄ or crassulacean acid metabolism.     

cDNA sequence and expression of a cold-responsive gene in Citrus unshiu

A cDNA clone encoding a protein (CuCOR19), the sequence of which is similar to Poncirus COR19, of the dehydrin family was isolated from the epicarp of Citrus unshiu. The molecular mass of the predicted protein was 18,980 daltons. CuCOR19 was highly hydrophilic and contained three repeating elements including Lys-rich motifs. The gene expression in leaves increased by cold stress.     

Effect of angiotensin II on myocardial collagen gene expression

Molecular and Cellular Biochemistry - Recent studies suggest that angiotensin II (angiotensin) may be involved in the regulation of metabolism of the cardiac extracellular matrix (ECM). Two major...     

Regulation of the expression of the rat angiotensin II receptor mRNA.

Regulation of the expression levels of the rat angiotensin II receptor mRNA in the adrenal, aorta, kidney, and brain was assessed by the competitive polymerase chain reaction method. The bilateral nephrectomy or the administration of Dup753 markedly reduced the expression levels of this receptor mRNA in the adrenal and brain stem, but not in the kidney nor aorta. A continuous infusion of angiotensin II increased the expression level of this receptor mRNA in the adrenal but not in the other tissues. It is suggested that the expression level of this receptor mRNA in the adrenal is dependent on the renin angiotensin aldosterone system.     

The human glucagon receptor encoding gene: structure, cDNA sequence and chromosomal localization

Characterization of the human glucagon-receptor-encoding gene (GGR) should provide a greater understanding of blood glucose regulation and may reveal a genetic basis for the pathogenesis of diabetes. A cDNA encoding a complete functional human glucagon receptor (GGR) was isolated from a liver cDNA library by a combination of polymerase chain reaction and colony hybridization. The cDNA encodes a receptor protein with 80% identity to rat GGR that binds [¹²⁵I] glucagon and transduces a signal leading to increases in the concentration of intracellular cyclic adenosine 3′,5′-monophosphate. Southern blot analysis of human DNA reveals a hybridization pattern consistent with a single GGR locus. In situ hybridization to metaphase chromosome preparations maps the GGR locus to chromosome 17q25. Analysis of the genomic sequence shows that the coding region spans over 5.5 kb and is interrupted by 12 introns.     

Cloning and expression of a novel angiotensin II receptor subtype.

Angiotensin II (AII) is a major regulator of cardiovascular function and fluid homeostasis. Recently, the cDNA for an AII receptor (AT1) was cloned from rat smooth muscle and bovine adrenal. To search for AII receptor subtypes, we amplified rat adrenal cortex cDNA by PCR using primers based on the AT1 receptor. The product was distinct from the AT1 receptor as indicated by restriction enzyme analysis and DNA sequencing. A full-length cDNA clone (2.2 kilobase pairs) encoding a novel AII receptor (AT3) was obtained by screening an adrenal cortex library. The AT3 cDNA encodes a Mr 40,959 protein with 95% amino acid identity to the rat smooth muscle receptor, but the overall nucleotide similarity is 71% due to low homology in the 5'- (58%) and 3'- (62%) untranslated regions. Expressed AT3 receptors in Xenopus oocytes and COS-7 cells mediate agonist-induced Ca2+ mobilization but are pharmacologically distinct from the AT1 receptors. AT3 mRNA is most abundant in the adrenal cortex and pituitary and differs from AT1 mRNA in its tissue distribution. The structural features of the AT3 receptor, including two additional potential phosphorylation sites for protein kinase C, could be related to the distinctive binding properties of the adrenal and vascular receptors and to their differential regulation during altered sodium intake.