Immune Netw.  2013 Oct;13(5):199-204. 10.4110/in.2013.13.5.199.

Syntenin Is Expressed in Human Follicular Dendritic Cells and Involved in the Activation of Focal Adhesion Kinase

• Cho W
• Kim H
• Lee JH
• Hong SH
• Choe J

• KMID: 1493614
• DOI: http://doi.org/10.4110/in.2013.13.5.199

Abstract

Syntenin is an adaptor molecule containing 2 PDZ domains which mediate molecular interactions with diverse integral or cytoplasmic proteins. Most of the results on the biological function of syntenin were obtained from studies with malignant cells, necessitating exploration into the role of syntenin in normal cells. To understand its role in normal cells, we investigated expression and function of syntenin in human lymphoid tissue and cells in situ and in vitro. Syntenin expression was denser in the germinal center than in the extrafollicular area. Inside the germinal center, syntenin expression was obvious in follicular dendritic cells (FDCs). Flow cytometric analysis with isolated cells confirmed a weak expression of syntenin in T and B cells and a strong expression in FDCs. In FDC-like cells, HK cells, most syntenin proteins were found in the cytoplasm compared to weak expression in the nucleus. To study the function of syntenin in FDC, we examined its role in the focal adhesion of HK cells by depleting syntenin by siRNA technology. Knockdown of syntenin markedly impaired focal adhesion kinase phosphorylation in HK cells. These results suggest that syntenin may play an important role in normal physiology as well as in cancer pathology.

Keyword

Syntenin; Follicular dendritic cell; FAK

MeSH Terms

B-Lymphocytes
Cytoplasm
Dendritic Cells, Follicular*
Focal Adhesion Protein-Tyrosine Kinases*
Focal Adhesions*
Germinal Center
Humans*
Lymphoid Tissue
PDZ Domains
Phosphorylation
Proteins
RNA, Small Interfering
Syntenins*
Focal Adhesion Protein-Tyrosine Kinases
Proteins
RNA, Small Interfering
Syntenins

Figure

• 

  Figure 1 Distribution of syntenin molecules in human tonsil tissue. Cryosections of a normal tonsil were subjected to immunohistochemical analyses. Sections were dual stained with anti-syntenin and anti-CD3 (T cell) (A), anti-CD19 (B cell) (B), or CNA.42 (FDC) (C) antibodies. Colocalization of syntenin (green) with other molecules (red) was visualized as yellow in merged panels of confocal microscopic analyses. The results were reproduced in three independent experiments.

• 

  Figure 2 Syntenin expression levels in lymphocytes and HK cells. T and B cells were freshly isolated from tonsils. HK cells were prepared as described in MATERIALS AND METHODS. (A) Immunoblotting analysis of syntenin expression in lymphocytes and HK cells. β-actin was used to demonstrate equal loading of lysates. (B) After membrane permeabilization, the syntenin expression levels were determined by a flow cytometer. Gray histograms were obtained by using isotype-matched control antibody. Representative results of three reproducible experiments.

• 

  Figure 3 Subcellular localization of syntenin in HK cells. (A) HK cells were subjected to confocal microscopic analysis after staining with anti-syntenin antibody and DAPI. (B) Localization of syntenin in cytoplasmic and nuclear fractions was examined by immunoblotting. Scale bars, 50µm.

• 

  Figure 4 Syntenin knockdown impairs FAK activation in HK cells. (A) Syntenin molecules in HK cells were knocked down by transfection with syntenin siRNA as evaluated by immunoblotting analysis. (B) HK cells transfected with syntenin or control siRNA were allowed to attach to tissue-culture treated plastics. At the indicated time points, cells were harvested to measure the phosphorylation degrees of FAK proteins. Representative of two reproducible data.

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