TY - JOUR

T1 - Complex Determinants in Specific Members of the Mannose Receptor Family Govern Collagen Endocytosis

AU - Jürgensen, Henrik J.

AU - Johansson, Kristina

AU - Madsen, Daniel H

AU - Porse, Astrid

AU - Melander, Maria C

AU - Sørensen, Kristine R.

AU - Nielsen, Christoffer

AU - Bugge, Thomas H

AU - Behrendt, Niels

AU - Engelholm, Lars H.

PY - 2014

Y1 - 2014

N2 - Members of the well-conserved mannose receptor (MR) protein family have been functionally implicated in diverse biological and pathological processes. Importantly, a proposed common function is the internalization of collagen for intracellular degradation occurring during bone development, cancer invasion, and fibrosis protection. This functional relationship is suggested by a common endocytic capability and a candidate collagen-binding domain. Here we conducted a comparative investigation of each member's ability to facilitate intracellular collagen degradation. As expected, the family members uPARAP/Endo180 and MR bound collagens in a purified system and internalized collagens for degradation in cellular settings. In contrast, the remaining family members, PLA2R and DEC-205, showed no collagen binding activity and were unable to mediate collagen internalization. To pinpoint the structural elements discriminating collagen from non-collagen receptors, we constructed a series of receptor chimeras and loss- and gain-of-function mutants. Using this approach we identified a critical collagen binding loop in the suggested collagen binding region (an FN-II domain) in uPARAP/Endo180 and MR, which was different in PLA2R or DEC-205. However, we also found that an active FN-II domain was not a sufficient determinant to allow collagen internalization through these receptors. Nevertheless, this ability could be acquired by the transfer of a larger segment of uPARAP/Endo180 (the Cys-rich domain, the FN-II domain and two CTLDs) to DEC-205. These data underscore the importance of the FN-II domain in uPARAP/Endo180 and MR-mediated collagen internalization but at the same time uncover a critical interplay with flanking domains.

AB - Members of the well-conserved mannose receptor (MR) protein family have been functionally implicated in diverse biological and pathological processes. Importantly, a proposed common function is the internalization of collagen for intracellular degradation occurring during bone development, cancer invasion, and fibrosis protection. This functional relationship is suggested by a common endocytic capability and a candidate collagen-binding domain. Here we conducted a comparative investigation of each member's ability to facilitate intracellular collagen degradation. As expected, the family members uPARAP/Endo180 and MR bound collagens in a purified system and internalized collagens for degradation in cellular settings. In contrast, the remaining family members, PLA2R and DEC-205, showed no collagen binding activity and were unable to mediate collagen internalization. To pinpoint the structural elements discriminating collagen from non-collagen receptors, we constructed a series of receptor chimeras and loss- and gain-of-function mutants. Using this approach we identified a critical collagen binding loop in the suggested collagen binding region (an FN-II domain) in uPARAP/Endo180 and MR, which was different in PLA2R or DEC-205. However, we also found that an active FN-II domain was not a sufficient determinant to allow collagen internalization through these receptors. Nevertheless, this ability could be acquired by the transfer of a larger segment of uPARAP/Endo180 (the Cys-rich domain, the FN-II domain and two CTLDs) to DEC-205. These data underscore the importance of the FN-II domain in uPARAP/Endo180 and MR-mediated collagen internalization but at the same time uncover a critical interplay with flanking domains.

KW - Amino Acid Sequence

KW - Animals

KW - Cell Line

KW - Collagen

KW - Drosophila

KW - Endocytosis

KW - Fibroblasts

KW - HEK293 Cells

KW - HeLa Cells

KW - Humans

KW - Insects

KW - Lectins, C-Type

KW - Ligands

KW - Mannose-Binding Lectins

KW - Membrane Glycoproteins

KW - Mice

KW - Molecular Sequence Data

KW - Plasmids

KW - Protein Binding

KW - Protein Structure, Tertiary

KW - Receptors, Cell Surface

KW - Receptors, Mitogen

KW - Sequence Homology, Amino Acid

KW - Structure-Activity Relationship

U2 - 10.1074/jbc.M113.512780

DO - 10.1074/jbc.M113.512780

M3 - Journal article

C2 - 24500714

VL - 289

SP - 7935

EP - 7947

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 11

ER -