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Nepmucin, a novel HEV sialomucin, mediates L-selectin-dependent lymphocyte rolling and promotes lymphocyte adhesion under flow.

ABSTRACT: Lymphocyte trafficking to lymph nodes (LNs) is initiated by the interaction between lymphocyte L-selectin and certain sialomucins, collectively termed peripheral node addressin (PNAd), carrying specific carbohydrates expressed by LN high endothelial venules (HEVs). Here, we identified a novel HEV-associated sialomucin, nepmucin (mucin not expressed in Peyer's patches [PPs]), that is expressed in LN HEVs but not detectable in PP HEVs at the protein level. Unlike conventional sialomucins, nepmucin contains a single V-type immunoglobulin (Ig) domain and a mucin-like domain. Using materials affinity-purified from LN lysates with soluble L-selectin, we found that two higher molecular weight species of nepmucin (75 and 95 kD) were decorated with oligosaccharides that bind L-selectin as well as an HEV-specific MECA-79 monoclonal antibody. Electron microscopic analysis showed that nepmucin accumulates in the extended luminal microvillus processes of LN HEVs. Upon appropriate glycosylation, nepmucin supported lymphocyte rolling via its mucin-like domain under physiological flow conditions. Furthermore, unlike most other sialomucins, nepmucin bound lymphocytes via its Ig domain, apparently independently of lymphocyte function-associated antigen 1 and very late antigen 4, and promoted shear-resistant lymphocyte binding in combination with intercellular adhesion molecule 1. Collectively, these results suggest that nepmucin may serve as a dual-functioning PNAd in LN HEVs, mediating both lymphocyte rolling and binding via different functional domains.

SUBMITTER: Umemoto E

PROVIDER: S-EPMC2118321 | biostudies-literature | 2006 Jun

REPOSITORIES: biostudies-literature

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Nepmucin, a novel HEV sialomucin, mediates L-selectin-dependent lymphocyte rolling and promotes lymphocyte adhesion under flow.

Umemoto Eiji E Tanaka Toshiyuki T Kanda Hidenobu H Jin Soojung S Tohya Kazuo K Otani Kazuhiro K Matsutani Takahiro T Matsumoto Masanori M Ebisuno Yukihiko Y Jang Myoung Ho MH Fukuda Minoru M Hirata Takako T Miyasaka Masayuki M

The Journal of experimental medicine 20060605 6

Lymphocyte trafficking to lymph nodes (LNs) is initiated by the interaction between lymphocyte L-selectin and certain sialomucins, collectively termed peripheral node addressin (PNAd), carrying specific carbohydrates expressed by LN high endothelial venules (HEVs). Here, we identified a novel HEV-associated sialomucin, nepmucin (mucin not expressed in Peyer's patches [PPs]), that is expressed in LN HEVs but not detectable in PP HEVs at the protein level. Unlike conventional sialomucins, nepmucin ...[more]

PMID: 16754720

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Project description:Selectin-ligand interactions mediate tethering and rolling of circulating leukocytes on the vessel wall during inflammation. Extensive study has been devoted to elucidating the kinetic and mechanical constraints of receptor-ligand-interaction-mediated leukocyte adhesion, yet many questions remain unanswered. Here, we describe our design of an inverted flow chamber to compare adhesions of HL-60 cells to E-selectin in the upright and inverted orientations. This new, to our knowledge, design allowed us to evaluate the effect of gravity and to investigate the mechanisms of flow-enhanced adhesion. Cell rolling in the two orientations was qualitatively similar, and the quantitative differences can be explained by the effect of gravity, which promotes free-flowing cells to tether and detached cells to reattach to the surface in the upright orientation but prevents such attachment from happening in the inverted orientation. We characterized rolling stability by the lifetime of rolling adhesion and detachment of rolling cells, which could be easily measured in the inverted orientation, but not in the upright orientation because of the reattachment of transiently detached cells. Unlike the transient tether lifetime of E-selectin-ligand interaction, which exhibited triphasic slip-catch-slip bonds, the lifetime of rolling adhesion displayed a biphasic trend that first increased with the wall shear stress, reached a maximum at 0.4 dyn/cm(2), and then decreased gradually. We have developed a minimal mathematical model for the probability of rolling adhesion. Comparison of the theoretical predictions to data has provided model validation and allowed evaluation of the effective two-dimensional association on-rate, kon, and the binding affinity, Ka, of the E-selectin-ligand interaction. kon increased with the wall shear stress from 0.1 to 0.7 dyn/cm(2). Ka first increased with the wall shear stress, reached a maximum at 0.4 dyn/cm(2), and then decreased gradually. Our results provide insights into how the interplay between flow-dependent on-rate and off-rate of E-selectin-ligand bonds determine flow-enhanced cell rolling stability.

Project description:Lung cancer is a severe disease threatening human health worldwide. Distant hematogenous metastasis results in poor prognosis and death of lung cancer patients. In the present study, we investigated the effect of circulatory platelets (PLTs) on hematogenous metastasis of non-small cell lung carcinoma (NSCLC). Laser scanning confocal microscopy was employed to assay the expression of P-selectin in lung cancer tissue, paracancerous tissue and distant tissue, respectively. Meanwhile, fluorescence-activated cell sorting (FACS) was used to determine P-selectin activation in peripheral blood. Purified PLTs were co-cultured with A549 cells and human vascular endothelial cells (HuvECs). Subsequently, the formation of PLT-lung cancer cell complexes and their effects on rolling and adhesion of A549 on the surface of vascular endothelium were assayed. Integrin ?3, ?5, ?1, ICAM-1 and VCAM-1 mRNAs and proteins were measured by reverse RT-PCR and western blot analysis, respectively. The expression of P-selectin in lung adenocarcinoma tissue was significantly stronger compared to that in paracancerous and distant tissues. P-selectin activation in peripheral blood in lung adenocarcinoma was markedly enhanced. The rolling rate of A549 on HuvECs was significantly slowed down after co-culture of activated PLTs and A549 cells. The mRNA and protein levels of integrin ?3, ?5, ?1, ICAM-1 and VCAM-1 were significantly increased after the co-culture. In conclusion, the PLT-lung cancer cell complexes protected the lung cancer cells from mechanical injury under blood flow. Furthermore, up-regulated integrin ?3, ?5, ?1 and endothelial cell adhesion molecules ICAM-1 and VCAM-1 promoted the adhesion of A549 on vascular endothelial cells, which may be responsible for hematogenous metastasis of lung cancer.

Dataset Information

Nepmucin, a novel HEV sialomucin, mediates L-selectin-dependent lymphocyte rolling and promotes lymphocyte adhesion under flow.

Publications

Nepmucin, a novel HEV sialomucin, mediates L-selectin-dependent lymphocyte rolling and promotes lymphocyte adhesion under flow.

Similar Datasets

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