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Molecular cloning and characterization of the rat liver IL-6 signal transducing molecule, gp130
Y Wang1, J E Nesbitt, N L Fuentes
1Department of Cell Biology, University of Alabama, Birmingham 35294-0005.
Insights
Researchers cloned and analyzed rat liver gp130, the interleukin-6 (IL-6) signal transducer. Rat gp130 showed high homology to human gp130, suggesting conserved function across species in IL-6 signaling pathways.
Area of Science:
- Molecular Biology
- Immunology
- Cell Biology
Background:
- Interleukin-6 (IL-6) is a key cytokine involved in various cellular responses.
- IL-6 signaling requires interaction with its receptor and the signal transducer gp130.
- Previous studies reported the human gp130 nucleotide sequence.
Purpose of the Study:
- To clone and analyze the gp130 molecule from rat liver.
- To compare rat gp130 with human gp130 to understand structural and functional conservation.
- To investigate the expression of gp130 mRNA in different rat cell types.
Main Methods:
- Cloning and sequencing of rat liver gp130.
- Sequence comparison between rat and human gp130.
- Ribonuclease protection assays to detect gp130 mRNA.
Main Results:
- The rat gp130 molecule was successfully cloned and sequenced.
- Rat and human gp130 exhibited 78% overall amino acid homology and 94% identity in the growth factor signaling domain.
- gp130 mRNA was detected in rat hepatocytes, astrocytes, fibroblasts, and endothelial cells, with two main species (7.5 kb and 9.0 kb).
Conclusions:
- The high homology suggests conserved function of gp130 in IL-6 signal transduction across species.
- The presence of gp130 mRNA in multiple cell types indicates its broad role in mediating IL-6 responses.
- Cell-specific proteins likely modulate the distinct cellular responses to IL-6 downstream of gp130 activation.
Abstract:
Interleukin-6 (IL-6) is a multifunctional cytokine that exerts its effects on different target cells by interacting with a specific receptor. This interaction leads to the association and activation of a second membrane glycoprotein, gp130, which is the IL-6 signal transducing molecule. The nucleotide sequence of gp130 from a human B-cell line has been reported. We report here the cloning and sequence analysis of the gp130 molecule derived from rat liver. Comparison of gp130 molecules from the different species and cell types reveals 78% overall amino acid homology and 94% identity in the growth factor signaling domain. Two gp130 mRNA species, a moderately abundant species of 7.5 kb and a lesser one of 9.0 kb, were present in rat hepatocytes. Ribonuclease protection analyses demonstrated the presence of gp130 mRNA in four different nontransformed cell types: hepatocytes, astrocytes, fibroblasts, and endothelial cells. The sequences between both gp130s in the different cell types are quite similar, supporting the prediction that the different responses initiated by IL-6 on different target cells are modulated by cell-specific proteins distal to the activated gp130 molecule.
