cDNA Cloning and Distribution of Neuromedin U and its Receptor in the Rabbit
Neuromedin U (NMU) is a kind of peptides that was initially purified from the porcine spinal cord. There are two peptides NMU-25 and NMU-8 with similar biological functions. NMU is found in peripheral organs such as gastrointestinal (GI) tract and the central nervous system (CNS). NMU has two receptors NMU-R1 and NMU-R2.
NMU-R1 is expressed particularly in the various peripheral tissues, whereas NMU-R2 is expressed in the central nervous system. However, the expression and function of NMU in the rabbit remained unclear. In this study, a novel partial cDNA cloning and expression of NMU, NMU-R1 and NMU-R2 mRNAs in 30 rabbit tissues
were investigated using semi-quantitative RT-PCR. The specific fragments were amplified and target cDNA fragment lengths were 443, 366 and 203 bp, respectively consistent with the expected size of the fragment, and clear bands. The cDNA cloned of rabbit NMU, NMU-R1 and NMU-R2 sequences were found to be 84%, 84% and 87% identical to those of the corresponding human homologues, respectively. The rabbit NMU, NMU-R1 and NMU-R2 cDNAs were encoded as 147,122 and 67 amino acid sequences, respectively. Meanwhile, the rabbit NMU-R1 and NMU-R2 amino acid sequence were found to have a typical transmembrane structure of GPCR.
The results of RT-PCR analysis showed that the expression of NMU, NMU-R1 and NMU-R2 mRNAs was found in the central nervous system and in the peripheral tissues, whereas NMU mRNAs were more abundant in the peripheral tissues. These results revealed that the NMU, NMU-R1 and NMU-R2 mRNAs were expressed in rabbit tissues in various distribution patterns. The study provided the experimental data for further research on the physiological function of NMU and its mechanisms of action in rabbits.