Cellular uptake of ribonuclease A relies on anionic glycans.
Bovine pancreatic ribonuclease (RNase A) can enter human cells, even though it lacks a cognate cell-surface receptor protein. Here, we report on the biochemical basis for its cellular uptake. Analyses in vitro and in cellulo revealed that RNase A interacts tightly with abundant cell-surface proteoglycans containing glycosaminoglycans, such as heparan sulfate and chondroitin sulfate, as well as with sialic acid-containing glycoproteins. The uptake of RNase A correlates with cell anionicity, as quantified by measuring electrophoretic mobility. The cellular binding and uptake of RNase A contrast with those of Onconase, an amphibian homologue that does not interact tightly with anionic cell-surface glycans. As anionic glycans are especially abundant on human tumor cells, our data predicate utility for mammalian ribonucleases as cancer chemotherapeutic agents.
Department of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States.
Tzu-Yuan
TY
Chao
Luke D
LD
Lavis
Ronald T
RT
Raines
D000818:Animals; D000838:Anions / Q000737:chemistry* / Q000378:metabolism*; D016466:CHO Cells; D002417:Cattle; D002460:Cell Line; D049109:Cell Proliferation; D002809:Chondroitin Sulfates / Q000737:chemistry / Q000378:metabolism; D002846:Chromatography, Affinity; D006224:Cricetinae; D003412:Cricetulus; D005434:Flow Cytometry; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism; D006025:Glycosaminoglycans / Q000737:chemistry / Q000378:metabolism; D006497:Heparan Sulfate / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008856:Microscopy, Fluorescence; D008970:Molecular Weight; D019158:N-Acetylneuraminic Acid / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D012259:Ribonuclease, Pancreatic / Q000737:chemistry* / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000838:Anions; D002809:Chondroitin Sulfates; D006023:Glycoproteins; D006025:Glycosaminoglycans; D006497:Heparan Sulfate; D019158:N-Acetylneuraminic Acid; D011134:Polysaccharides; D012259:Ribonuclease, Pancreatic