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L-MBP is expressed in epithelial cells of mouse small intestine
Kazuhide Uemura1, Masako Saka, Tomoaki Nakagawa
1Department of Biological Chemistry, Core Research for Science and Technology Project, Japan Science and Technology Corp., Graduate School of Pharmaceutical Sciences, Kyoto University, Japan.
Abstract:
The mannan-binding proteins (L-MBP and S-MBP, also denoted MBL-C and MBL-A), mainly produced in liver and existing in liver and serum, play important roles in the innate immunity against a variety of pathogens. Total RNA from mouse tissues were screened for MBP mRNA by RT-PCR. In addition to liver, S-MBP mRNA was detected in lung, kidney, and testis, and L-MBP mRNA was detected in kidney, thymus, and small intestine. Quantitative RT-PCR revealed that the small intestine is a predominant site of extrahepatic expression of L-MBP. Western blotting with polyclonal Abs against rat L-MBP demonstrated this protein in Triton X-100 extracts of the small intestine obtained from mice that had undergone systemic perfusion. Immunohistochemical staining with an mAb against mouse L-MBP and in situ hybridization revealed that L-MBP is selectively expressed in some villous epithelial cells of the small intestine. These findings suggest that L-MBP plays a role in mucosal innate immunity.
Insights
Mannan-binding proteins (MBPs) are crucial for innate immunity. This study found L-MBP mRNA and protein predominantly expressed in the mouse small intestine, suggesting a role in mucosal immunity.
Area of Science:
- Immunology
- Molecular Biology
Background:
- Mannan-binding proteins (L-MBP and S-MBP, also known as MBL-C and MBL-A) are key components of the innate immune system, primarily synthesized in the liver and found in serum.
- These proteins play a vital role in defending against diverse pathogens.
Purpose of the Study:
- To investigate the tissue distribution and expression patterns of L-MBP and S-MBP mRNA and protein in mice.
- To determine the specific cellular localization of L-MBP in the small intestine.
Main Methods:
- Screening of total RNA from various mouse tissues for MBP mRNA using Reverse Transcription Polymerase Chain Reaction (RT-PCR).
- Quantitative RT-PCR to assess L-MBP expression levels.
- Western blotting to detect L-MBP protein in small intestine extracts.
- Immunohistochemical staining and in situ hybridization for cellular localization of L-MBP.
Main Results:
- S-MBP mRNA was detected in the liver, lung, kidney, and testis.
- L-MBP mRNA was found in the liver, kidney, thymus, and small intestine.
- Quantitative analysis indicated the small intestine as a primary site for extrahepatic L-MBP expression.
- L-MBP protein was confirmed in small intestine extracts.
- Immunohistochemistry and in situ hybridization revealed selective L-MBP expression in villous epithelial cells of the small intestine.
Conclusions:
- The small intestine is a significant site of L-MBP expression beyond the liver.
- L-MBP is specifically localized to epithelial cells in the small intestine's villi.
- These findings suggest a potential role for L-MBP in mucosal innate immunity.