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The Th1-specific costimulatory molecule, m150, is a posttranslational isoform of lysosome-associated membrane
Durbaka V R Prasad1, Vrajesh V Parekh, Bimba N Joshi
1National Centre For Cell Science, Pune, India.
Abstract:
In an earlier report, we had shown a 150-kDa protein termed as M150, isolated from the surface of activated macrophages, to possess costimulatory activity for CD4(+) T cells. Significantly, this protein was found to specifically elicit Th1 responses. In this study, we characterize M150, which belongs to a unique subset of the lysosome-associated membrane protein-1 glycoprotein. Interestingly, the costimulatory activity of M150 depends on its posttranslational modification, which has a distinct glycosylation pattern restricted to macrophages. Furthermore, it has been demonstrated that in addition to stimulating Th1-specific responses, M150 is also capable of driving differentiation of naive CD4(+) T cells into the Th1 subset. This altered posttranslational modification of housekeeping protein appears to represent a novel pathway by which APCs can additionally regulate T cell responses.
Insights
A novel macrophage protein, M150, provides costimulatory signals for CD4(+) T cells and drives Th1 cell differentiation. Its unique posttranslational modification, a glycosylation pattern, is key to this immune response regulation.
Area of Science:
- Immunology
- Cell Biology
Background:
- Activated macrophages express a 150-kDa protein (M150) with costimulatory activity for CD4(+) T cells.
- M150 was previously shown to specifically elicit T-helper 1 (Th1) responses.
Purpose of the Study:
- To characterize the M150 protein and elucidate the mechanisms underlying its T cell stimulatory functions.
- To investigate the role of posttranslational modifications in M150's costimulatory activity.
Main Methods:
- Protein isolation and characterization from activated macrophages.
- Analysis of M150's posttranslational modifications, including glycosylation patterns.
- Assessment of M150's effects on CD4(+) T cell activation and differentiation in vitro.
Main Results:
- M150 belongs to a unique subset of lysosome-associated membrane protein-1 (LAMP-1) glycoproteins.
- The costimulatory activity of M150 is dependent on its posttranslational modification, specifically a macrophage-restricted glycosylation pattern.
- M150 stimulates Th1-specific responses and drives naive CD4(+) T cells to differentiate into the Th1 subset.
Conclusions:
- Altered posttranslational modification of M150 represents a novel pathway for antigen-presenting cells (APCs) to regulate T cell responses.
- M150 is a key regulator of Th1 cell differentiation through its unique macrophage-specific glycosylation.