TY - JOUR
T1 - The specificity of the malarial VAR2CSA protein for chondroitin sulfate depends on 4-O-sulfation and ligand accessibility
AU - Spliid, Charlotte B
AU - Toledo, Alejandro Gomez
AU - Sanderson, Patience
AU - Mao, Yang
AU - Gatto, Francesco
AU - Gustavsson, Tobias
AU - Choudhary, Swati
AU - Saldanha, Ana L
AU - Vogelsang, Rasmus P
AU - Gögenur, Ismail
AU - Theander, Thor G
AU - Leach, Franklin E
AU - Amster, I Jonathan
AU - Esko, Jeffrey D
AU - Salanti, Ali
AU - Clausen, Thomas Mandel
N1 - Published by Elsevier Inc.
PY - 2021/12
Y1 - 2021/12
N2 - Placental malaria infection is mediated by the binding of the malarial VAR2CSA protein to the placental glycosaminoglycan, chondroitin sulfate. Recombinant subfragments of VAR2CSA (rVAR2) have also been shown to bind specifically and with high affinity to cancer cells and tissues, suggesting the presence of a shared type of oncofetal chondroitin sulfate (ofCS) in the placenta and in tumors. However, the exact structure of ofCS and what determines the selective tropism of VAR2CSA remains poorly understood. In this study, ofCS was purified by affinity chromatography using rVAR2 and subjected to detailed structural analysis. We found high levels of N-acetylgalactosamine 4-O-sulfation (∼80-85%) in placenta- and tumor-derived ofCS. This level of 4-O-sulfation was also found in other tissues that do not support parasite sequestration, suggesting that VAR2CSA tropism is not exclusively determined by placenta- and tumor-specific sulfation. Here, we show that both placenta and tumors contain significantly more chondroitin sulfate moieties of higher molecular weight than other tissues. In line with this, CHPF and CHPF2, which encode proteins required for chondroitin polymerization, are significantly upregulated in most cancer types. CRISPR/Cas9 targeting of CHPF and CHPF2 in tumor cells reduced the average molecular weight of cell-surface chondroitin sulfate and resulted in a marked reduction of rVAR2 binding. Finally, utilizing a cell-based glycocalyx model, we showed that rVAR2 binding correlates with the length of the chondroitin sulfate chains in the cellular glycocalyx. These data demonstrate that the total amount and cellular accessibility of chondroitin sulfate chains impact rVAR2 binding and thus malaria infection.
AB - Placental malaria infection is mediated by the binding of the malarial VAR2CSA protein to the placental glycosaminoglycan, chondroitin sulfate. Recombinant subfragments of VAR2CSA (rVAR2) have also been shown to bind specifically and with high affinity to cancer cells and tissues, suggesting the presence of a shared type of oncofetal chondroitin sulfate (ofCS) in the placenta and in tumors. However, the exact structure of ofCS and what determines the selective tropism of VAR2CSA remains poorly understood. In this study, ofCS was purified by affinity chromatography using rVAR2 and subjected to detailed structural analysis. We found high levels of N-acetylgalactosamine 4-O-sulfation (∼80-85%) in placenta- and tumor-derived ofCS. This level of 4-O-sulfation was also found in other tissues that do not support parasite sequestration, suggesting that VAR2CSA tropism is not exclusively determined by placenta- and tumor-specific sulfation. Here, we show that both placenta and tumors contain significantly more chondroitin sulfate moieties of higher molecular weight than other tissues. In line with this, CHPF and CHPF2, which encode proteins required for chondroitin polymerization, are significantly upregulated in most cancer types. CRISPR/Cas9 targeting of CHPF and CHPF2 in tumor cells reduced the average molecular weight of cell-surface chondroitin sulfate and resulted in a marked reduction of rVAR2 binding. Finally, utilizing a cell-based glycocalyx model, we showed that rVAR2 binding correlates with the length of the chondroitin sulfate chains in the cellular glycocalyx. These data demonstrate that the total amount and cellular accessibility of chondroitin sulfate chains impact rVAR2 binding and thus malaria infection.
KW - Antigens, Protozoan/chemistry
KW - Chondroitin Sulfates/chemistry
KW - Female
KW - Glycocalyx/chemistry
KW - HEK293 Cells
KW - HeLa Cells
KW - Humans
KW - Malaria, Falciparum/genetics
KW - N-Acetylgalactosaminyltransferases/genetics
KW - Placenta/metabolism
KW - Plasmodium falciparum/genetics
KW - Pregnancy
KW - Protozoan Proteins/chemistry
UR - http://www.scopus.com/inward/record.url?scp=85120867711&partnerID=8YFLogxK
U2 - 10.1016/j.jbc.2021.101391
DO - 10.1016/j.jbc.2021.101391
M3 - Journal article
C2 - 34762909
SN - 0021-9258
VL - 297
SP - 101391
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 6
M1 - 101391
ER -