Antibody-induced receptor loss. Different fates for asialoglycoproteins and the asialoglycoprotein receptor in HepG2 cells.

Schwartz, Alan L.; Ciechanover, Aaron; Merritt, Stephen C.; Turkewitz, Aaron P.

doi:10.1016/s0021-9258(18)66857-7

Cited by 42 publications

(6 citation statements)

References 30 publications

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“…Previous studies [64][65][66][67][68] have shown that certain agents or hormones may change the number of binding sites without affecting the number of receptors at the plasma membrane level, supporting the hypothesis proposed by Triggle [69] that cryptic receptors or receptor reserve recruitment may act as modulators of cell sensitivity. Our finding that UDCA and ketoconazole uncover receptors present at the membrane surface, which are normally not able to bind the LDL particle, is in agreement with these observations.…”

Section: Discussionsupporting

confidence: 62%

Ursodeoxycholic acid increases low-density lipoprotein binding, uptake and degradation in isolated hamster hepatocytes

Bouscarel

Fromm

Ceryak

et al. 1991

Biochemical Journal

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Ursodeoxycholic acid (UDCA), in contrast to both chenodeoxycholic acid (CDCA), its 7 alpha-epimer, and lithocholic acid, enhanced receptor-dependent low-density lipoprotein (LDL) uptake and degradation in isolated hamster hepatocytes. The increase in cell-associated LDL was time- and concentration-dependent, with a maximum effect observed at approx. 60 min with 1 mM-UDCA. This increase was not associated with a detergent effect of UDCA, as no significant modifications were observed either in the cellular release of lactate dehydrogenase or in Trypan Blue exclusion. The effect of UDCA was not due to a modification of the LDL particle, but rather was receptor-related. UDCA (1 mM) maximally increased the number of 125I-LDL-binding sites (Bmax.) by 35%, from 176 to 240 ng/mg of protein, without a significant modification of the binding affinity. Furthermore, following proteolytic degradation of the LDL receptor with Pronase, specific LDL binding decreased to the level of non-specific binding, and the effect of UDCA was abolished. Conversely, the trihydroxy 7 beta-hydroxy bile acid ursocholic acid and its 7 alpha-epimer, cholic acid, induced a significant decrease in LDL binding by approx. 15%. The C23 analogue of UDCA (nor-UDCA) and CDCA did not affect LDL binding. On the other hand, UDCA conjugated with either glycine (GUDCA) or taurine (TUDCA), increased LDL binding to the same extent as did the free bile acid. The half maximum time (t1/2) to reach the full effect was 1-2 min for UDCA and TUDCA, while GUDCA had a much slower t1/2 of 8.3 min. Ketoconazole (50 microM), an antifungal agent, increased LDL binding, but this effect was not additive when tested in the presence of 0.7 mM-UDCA. The results of the studies indicate that, in isolated hamster hepatocytes, the UDCA-induced increase in receptor-dependent LDL binding and uptake represents a direct effect of this bile acid. The action of the bile acid is closely related to its specific structural conformation, since UDCA and its conjugates are the only bile acids shown to express this ability thus far. However, certain agents other than bile acids, such as ketoconazole, have a similar effect. Finally, the studies suggest that the recruitment of LDL receptors from a latent pool in the hepatocellular membrane may be the mechanism by which UDCA exerts its direct effect.

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Section: Discussionsupporting

confidence: 62%

Ursodeoxycholic acid increases low-density lipoprotein binding, uptake and degradation in isolated hamster hepatocytes

Bouscarel

Fromm

Ceryak

et al. 1991

Biochemical Journal

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“…Note that in contrast to antibody cross-linking studies (Enns et al, 1983;Kasuga et al, 1981;Larrick et al, 1985;Lesley et al, 1989;Roth et al, 1983;Schwartz et al, 1986;Weissman et al, 1986), Tfl0 was released from TRVb-1 cells intact. However, extremely large forms of multivalent-Tf, those composed of greater than 10 Tf molecules per particle, were redirected out of the recycling pathway and degraded, presumably by the same mechanism responsible for the degradation induced by anti-receptor antibodies.…”

Section: The Recycling Compartment Has Sorting Functionsmentioning

confidence: 86%

“…Receptor redistribution has also been demonstrated indirectly through the use of antibodies and colloidal gold conjugates directed toward surface receptors (Enns et al, 1983;Kasuga et al, 1981;Larrick et al, 1985;Lesley et al, 1989;Neutra et al, 1985;Roth et al, 1983;Schwartz et al, 1986;Weissman et al, 1986). The cellular mechanism and physiological function of this sorting induced by cross-linking remains unclear as does its variable effect.…”

mentioning

confidence: 99%

“…Although antibody treatment generally produces a redistribution of the TfR, only a portion of the cross-linked TfR are degraded. The site of antibodyinduced degradation has been suggested to be the lysosome, yet in at least one system, antibody induced degradation of asialoglycoprotein receptor was not affected by lysosomal protease inhibitors, or by incubation at 18°C (Schwartz et al, 1986). The variable effect upon receptor trafficking caused by antibody cross-linking may in part be explained by the varying extent of receptor aggregation induced by the multivalent binding of antibody.…”

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confidence: 99%

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Oligomerized transferrin receptors are selectively retained by a lumenal sorting signal in a long-lived endocytic recycling compartment.

Marsh

Leopold

Jones

et al. 1995

The Journal of Cell Biology

145

116

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Abstract. Cross-linking of surface receptors results in altered receptor trafficking in the endocytic system. To better understand the cellular and molecular mechanisms by which receptor cross-linking affects the intracellular trafficking of both ligand and receptor, we studied the intracellular trafficking of the transferrin receptor (TfR) bound to multivalent-transferrin (Tfl0) which was prepared by chemical cross-linking of transferrin (Tf). Tfl0 was internalized about two times slower than Tf and was retained four times longer than Tf, without being degraded in CHO cells. The intracellular localization of Tfl0 was investigated using fluorescence and electron microscopy. Tfl0 was not delivered to the lysosomal pathway followed by low density lipoprotein but remained accessible to Tf in the pericentriolar endocytic recycling compartment for at least 60 min. The retained Tfl0 was TfR-associated as demonstrated by a reduction in surface TfR number when cells were incubated with Tfl0. The presence of Tfx0 within the recycling compartment did not affect trafficking of subsequently endocytosed Tf. Retention of Tfl0 within the recycling compartment did not require the cytoplasmic domain of the TfR since Tfl0 exited cells with the same rate when bound to the wild-type TfR or a mutated receptor with only four amino acids in the cytoplasmic tail. Thus, cross-linking of surface receptors by a multivalent ligand acts as a lumenal retention signal within the recycling compartment. The data presented here show that the recycling compartment labeled by Tfl0 is a long-lived organelle along the early endosome recycling pathway that remains fusion accessible to subsequently endocytosed Tf.

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“…Therefore, targeted delivery of RSPOs could have potential therapeutic benefits for disease conditions where Wnt ligands are present but signaling is limited. ASGR (asialoglycoprotein receptor, also known as ASGPR) mediates clearance of desialylated, galactose-or N-acetylgalactosamine-terminating plasma glycoproteins via receptor mediated endocytosis for lysosomal degradation (Schwartz et al, 1986;Weigel and Yik, 2002). ASGR is thought to exist as a heterotrimer of two ASGR1 and one ASGR2 polypeptides -referred to as H1 and H2, respectively (Henis et al, 1990;Saxena et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Targeted protein degradation systems to enhance Wnt signaling

Sampathkumar,

Jung,

Chen

et al. 2023

Preprint

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Molecules that facilitate targeted protein degradation (TPD) offer great promise as novel therapeutics. Human hepatic lectin, asialoglycoprotein receptor (ASGR) is selectively expressed on hepatocytes. We have previously engineered an anti-ASGR1 antibody-mutant RSPO2 (RSPO2RA) fusion protein (called SWEETSTM) to drive tissue-specific degradation of ZNRF3/RNF43 E3-ubiquitin ligases, leading to hepatocyte specific enhanced Wnt signaling, proliferation, and restored liver function in mouse models. Such an antibody-RSPO2RA fusion molecule is currently in human clinical trials. In the current study, we identified two new ASGR1 and ASGR1/2 specific antibodies, 8M24 and 8G8. High-resolution crystal structures of ASGR1:8M24 and ASGR2:8G8 complexes revealed that these antibodies bind to distinct epitopes on the opposite sides of ASGR, away from the substrate binding site. Both antibodies enhanced Wnt-activity when assembled as SWEETS molecules with RSPO2RA through specific effects sequestering E3 ligases. In addition, 8M24-RSPO2RA and 8G8-RSPO2RA efficiently downregulated ASGR1 through TPD mechanisms. These results demonstrate the possibility of combining different therapeutic effects and different degradation mechanisms in a single molecule.

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Antibody-induced receptor loss. Different fates for asialoglycoproteins and the asialoglycoprotein receptor in HepG2 cells.

Cited by 42 publications

References 30 publications

Ursodeoxycholic acid increases low-density lipoprotein binding, uptake and degradation in isolated hamster hepatocytes

Ursodeoxycholic acid increases low-density lipoprotein binding, uptake and degradation in isolated hamster hepatocytes

Oligomerized transferrin receptors are selectively retained by a lumenal sorting signal in a long-lived endocytic recycling compartment.

Targeted protein degradation systems to enhance Wnt signaling

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