Limits...
Induced oligomerization targets Golgi proteins for degradation in lysosomes.

Tewari R, Bachert C, Linstedt AD - Mol. Biol. Cell (2015)

Bottom Line: These were targeted to the cis- and trans-Golgi, respectively, using domains from mannosidase-1 and galactosyltransferase.Significantly, upon oligomerization, each redistributed to peripheral punctae and was degraded.This occurred in the absence of detectable UPR activation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213.

No MeSH data available.


Related in: MedlinePlus

Oligomerization-induced trafficking is not associated with UPR activation. (A) Immunoblots using anti-Bip or anti-tubulin antibodies of extracts from nontransfected cells (lanes 1–3) or cells transfected with GPP130-GFP or GPP130-FM (lanes 4–6). The cells were untreated (Ø), tunicamycin treated (Tun) to induce the UPR, Mn treated (Mn) to cause endogenous GPP130 redistribution, left in AP (AP), or subjected to AP washout (w/o) to cause oligomerization of GPP130-FM. (B) Quantification of Bip recovery as a percentage of Bip levels in untreated cells (mean ± SEM, n = 3).
© Copyright Policy - creative-commons
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4666137&req=5

Figure 10: Oligomerization-induced trafficking is not associated with UPR activation. (A) Immunoblots using anti-Bip or anti-tubulin antibodies of extracts from nontransfected cells (lanes 1–3) or cells transfected with GPP130-GFP or GPP130-FM (lanes 4–6). The cells were untreated (Ø), tunicamycin treated (Tun) to induce the UPR, Mn treated (Mn) to cause endogenous GPP130 redistribution, left in AP (AP), or subjected to AP washout (w/o) to cause oligomerization of GPP130-FM. (B) Quantification of Bip recovery as a percentage of Bip levels in untreated cells (mean ± SEM, n = 3).

Mentions: Given the possibility that the pathway described here is a type of quality control, it seemed important, even if unlikely, to test whether our conditions causing oligomerization-induced trafficking of Golgi proteins also activated the unfolded protein response (UPR). For this purpose, we assayed up-regulation of the ATPase chaperone Bip, which is a standard UPR marker. As a positive control, HeLa cells were treated with tunicamycin to block N-glycosylation and activate the UPR (Oslowski and Urano, 2011). As expected, Bip levels increased (Figure 10). In contrast, treatment with Mn did not alter Bip levels. To test the effect of AP washout, we needed to transfect the cells with GPP130-FM. Transfection frequency was ∼70%, and we noted that transfection alone elevated the level of Bip somewhat. However, AP washout of the transfected cells yielded Bip levels that were identical to those of cells before AP washout or control transfected cells (Figure 10). Therefore, based on Bip level, the UPR was not activated under conditions in which oligomerized Golgi proteins are induced to leave the Golgi and undergo degradation. Taken together, the experiments here reveal a novel type of quality control in the Golgi in which clustered Golgi proteins are routed for degradation.


Induced oligomerization targets Golgi proteins for degradation in lysosomes.

Tewari R, Bachert C, Linstedt AD - Mol. Biol. Cell (2015)

Oligomerization-induced trafficking is not associated with UPR activation. (A) Immunoblots using anti-Bip or anti-tubulin antibodies of extracts from nontransfected cells (lanes 1–3) or cells transfected with GPP130-GFP or GPP130-FM (lanes 4–6). The cells were untreated (Ø), tunicamycin treated (Tun) to induce the UPR, Mn treated (Mn) to cause endogenous GPP130 redistribution, left in AP (AP), or subjected to AP washout (w/o) to cause oligomerization of GPP130-FM. (B) Quantification of Bip recovery as a percentage of Bip levels in untreated cells (mean ± SEM, n = 3).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4666137&req=5

Figure 10: Oligomerization-induced trafficking is not associated with UPR activation. (A) Immunoblots using anti-Bip or anti-tubulin antibodies of extracts from nontransfected cells (lanes 1–3) or cells transfected with GPP130-GFP or GPP130-FM (lanes 4–6). The cells were untreated (Ø), tunicamycin treated (Tun) to induce the UPR, Mn treated (Mn) to cause endogenous GPP130 redistribution, left in AP (AP), or subjected to AP washout (w/o) to cause oligomerization of GPP130-FM. (B) Quantification of Bip recovery as a percentage of Bip levels in untreated cells (mean ± SEM, n = 3).
Mentions: Given the possibility that the pathway described here is a type of quality control, it seemed important, even if unlikely, to test whether our conditions causing oligomerization-induced trafficking of Golgi proteins also activated the unfolded protein response (UPR). For this purpose, we assayed up-regulation of the ATPase chaperone Bip, which is a standard UPR marker. As a positive control, HeLa cells were treated with tunicamycin to block N-glycosylation and activate the UPR (Oslowski and Urano, 2011). As expected, Bip levels increased (Figure 10). In contrast, treatment with Mn did not alter Bip levels. To test the effect of AP washout, we needed to transfect the cells with GPP130-FM. Transfection frequency was ∼70%, and we noted that transfection alone elevated the level of Bip somewhat. However, AP washout of the transfected cells yielded Bip levels that were identical to those of cells before AP washout or control transfected cells (Figure 10). Therefore, based on Bip level, the UPR was not activated under conditions in which oligomerized Golgi proteins are induced to leave the Golgi and undergo degradation. Taken together, the experiments here reveal a novel type of quality control in the Golgi in which clustered Golgi proteins are routed for degradation.

Bottom Line: These were targeted to the cis- and trans-Golgi, respectively, using domains from mannosidase-1 and galactosyltransferase.Significantly, upon oligomerization, each redistributed to peripheral punctae and was degraded.This occurred in the absence of detectable UPR activation.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213.

No MeSH data available.


Related in: MedlinePlus