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Expression of kappa opioid receptors in human and monkey lymphocytes
L F Chuang1, T K Chuang, K F Killam
1Department of Medical Pharmacology and Toxicology, University of California, Davis 95616, USA.
Abstract:
mRNA encoding the kappa opioid receptor gene sequence was identified and isolated from various human lymphocytic cells: CEM x174 (a hybrid of T and B origin) cells, Jurkat-T4 cells, human peripheral blood mononuclear cells (PBMC) and purified CD4+ cells. Analyzing the cDNA sequences of RNA transcripts spanning the putative second extracellular loop, which has reported dynorphin specificity, and the seventh transmembrane domain revealed a 100% and 95% homology in amino acid sequence to corresponding kappa opioid receptor sequences in human placenta and rat brain, respectively. Expression of a similar kappa opioid receptor sequence could be detected in normal monkey PBMC but not in monkey PBMC in which the CD4+/CD8+ cell ratio (or CD4+ cell number) was significantly reduced due to prolonged SIV infection. These findings suggest that human and monkey lymphocytes constitutively express kappa opioid receptor mRNA.
Insights
Kappa opioid receptor mRNA is present in human and monkey lymphocytes. Its expression is reduced in monkeys with SIV infection, suggesting a role in immune cell function.
Area of Science:
- Immunology
- Neuroscience
- Molecular Biology
Background:
- The kappa opioid receptor (KOR) plays a role in various physiological processes.
- Understanding KOR expression in immune cells is crucial for exploring its immunomodulatory functions.
Purpose of the Study:
- To investigate the presence and sequence homology of kappa opioid receptor mRNA in human and monkey lymphocytes.
- To determine if KOR expression in lymphocytes is affected by viral infections like SIV.
Main Methods:
- Isolation and identification of mRNA encoding the kappa opioid receptor from human lymphocytic cell lines (CEM x174, Jurkat-T4) and primary cells (PBMC, CD4+).
- cDNA sequence analysis of KOR transcripts, focusing on extracellular loop and transmembrane domains.
- Detection of KOR mRNA expression in normal and SIV-infected monkey peripheral blood mononuclear cells (PBMC).
Main Results:
- Kappa opioid receptor mRNA was identified and isolated from various human lymphocyte populations.
- Human KOR sequences showed high amino acid homology to human placenta and rat brain KOR.
- KOR mRNA was detected in normal monkey PBMC but significantly reduced in PBMC from SIV-infected monkeys with decreased CD4+ cell counts.
Conclusions:
- Human and monkey lymphocytes constitutively express kappa opioid receptor mRNA.
- KOR expression in lymphocytes may be downregulated during viral infections.
- These findings suggest a potential role for KOR in immune cell function and viral pathogenesis.