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Tissue distribution and quantitation of the mRNAs for three rat tachykinin receptors
K Tsuchida1, R Shigemoto, Y Yokota
1Institute for Immunology, Kyoto University Faculty of Medicine, Japan.
Abstract:
The family of mammalian tachykinin receptors consists of substance P receptor (SPR), neuromedin K receptor (NKR) and substance K receptor (SKR). In this investigation, tissue and regional distributions of the mRNAs for the three rat tachykinin receptors were investigated by blot-hybridization and RNase-protection analyses using the previously cloned receptor cDNAs. SPR mRNA is widely distributed in both the nervous system and peripheral tissues and is expressed abundantly in the hypothalamus and olfactory bulb, as well as in the urinary bladder, salivary glands and small and large intestines. In contrast, NKR mRNA is predominantly expressed in the nervous system, particularly in the cortex, hypothalamus and cerebellum, whereas SKR mRNA expression is restricted to the peripheral tissues, being abundant in the urinary bladder, large intestine, stomach and adrenal gland. Thus, the mRNAs for the three tachykinin receptors show distinct patterns of expression between the nervous system and peripheral tissues. Blot-hybridization analysis in combination with S1 nuclease protection and primer-extension analyses revealed that there are two large forms of SKR mRNA expressed commonly in the peripheral tissues, and two additional small forms of the mRNA expressed specifically in the adrenal gland and eye. These analyses also showed that the multiple forms of SKR mRNA differ in the lengths of the 5' mRNA portions, and that the two small forms of the mRNA, if translated, encode a truncated SKR polypeptide lacking the first two transmembrane domains. This investigation thus provides the comprehensive analysis of the distribution and mode of expression of the mRNAs for the multiple peptide receptors and offers a new basis on which to interpret the diverse functions of multiple tachykinin peptides in the CNS and peripheral tissues.
Insights
Researchers mapped the distribution of three rat tachykinin receptors (SPR, NKR, SKR) mRNA in nervous and peripheral tissues. Distinct expression patterns were found, with SKR mRNA showing multiple forms in specific tissues.
Area of Science:
- Neuroscience
- Molecular Biology
- Pharmacology
Background:
- Mammalian tachykinin receptors include substance P receptor (SPR), neuromedin K receptor (NKR), and substance K receptor (SKR).
- Understanding the tissue and regional distribution of these receptor mRNAs is crucial for elucidating their diverse functions.
Purpose of the Study:
- To investigate the tissue and regional distributions of mRNAs for the three rat tachykinin receptors (SPR, NKR, SKR).
- To analyze the expression patterns and identify different forms of SKR mRNA.
Main Methods:
- Blot-hybridization and RNase-protection analyses were employed using cloned receptor cDNAs.
- S1 nuclease protection and primer-extension analyses were used to characterize SKR mRNA forms.
Main Results:
- SPR mRNA showed wide distribution in both nervous and peripheral tissues.
- NKR mRNA was predominantly found in the nervous system, while SKR mRNA expression was restricted to peripheral tissues.
- Multiple forms of SKR mRNA were identified, including tissue-specific variants in the adrenal gland and eye, with some potentially encoding truncated polypeptides.
Conclusions:
- The three tachykinin receptor mRNAs exhibit distinct expression patterns in the central nervous system and peripheral tissues.
- The identification of multiple SKR mRNA forms provides a basis for understanding the complex roles of tachykinin peptides.