PKCδ and ε regulate the morphological integrity of the ER–Golgi intermediate compartment (ERGIC) but not the anterograde and retrograde transports via the Golgi apparatus

Abstract

The ER-Golgi intermediate compartment (ERGIC) is an organelle through which cargo proteins pass and are being transferred by either anterograde or retrograde transport between the endoplasmic reticulum (ER) and the Golgi apparatus. We examined the effect of 80 different kinase inhibitors on ERGIC morphology and found that rottlerin, a PKCδ inhibitor, induced the dispersion of the perinuclear ERGIC into punctate structures. Rottlerin also delayed anterograde transport of vesicular stomatitis virus G protein (VSVG) from the ER to the Golgi and retrograde transport of cholera toxin from cell surface to the ER via the Golgi. RNA interference revealed that knockdown of PKCδ or ε resulted in the dispersion of the ERGIC, but unexpectedly did not inhibit VSVG and cholera toxin transport. We also found that rottlerin depolarized the mitochondrial membrane potential, as does carbonylcyanide-p-trifluoromethoxyphenylhydrazone (FCCP), an uncoupler, and demonstrated that a decrease in the intracellular adenosine triphosphate (ATP) levels by rottlerin might underlie the block in transports. These results suggest that PKCδ and ε specifically regulate the morphology of the ERGIC and that the maintenance of ERGIC structure is not necessarily required for anterograde and retrograde transports.

JNK1/2‐dependent phosphorylation of angulin‐1/LSR is required for the exclusive localization of angulin‐1/LSR and tricellulin at tricellular contacts in EpH4 epithelial sheet

“…; Sugawara et al . ). For this purpose, we used mouse mammary gland epithelial EpH4 cells that stably expressed claudin‐3 (Cl3) fused to the yellow fluorescence protein (Cl3‐YFP, EpH4‐Cl3; Matsuda et al .…”

“…; Sugawara et al . ). We found that the activity of JNK1 and JNK2, but not JNK3, was required for exclusive localization of angulin‐1/LSR at the tTJs, owing to their regulation of the phosphorylation state of angulin‐1/LSR (Figs and ).…”

“…; Sugawara et al . ). Protein kinases are the most versatile among the many regulators of protein localization and trafficking.…”

Golgi-Targeting Anticancer Natural Products

“…The cytotoxic effect of AG-1478 is much higher than that observed solely by EGFR inhibition, suggesting that the compound elicits its activity both via EGFR-dependent and EGFR-independent pathways. AG-1478 was also found as a hit compound in an image-based screen for inducers of Golgi disassembly [ 65 , 66 ]. It was subsequently found to inhibit the Sec7 domain of GBF1, a guanine nucleotide exchange factor for ARF.…”

Intermediate Compartment: A Sorting Station between the Endoplasmic Reticulum and the Golgi Apparatus

“…The level of p58/ERGIC-53 mRNA is up-regulated by the unfolded protein response (UPR), which also requires yeast Ypt1 function, supporting a link between this signaling pathway and ER-Golgi trafficking (Nyfeler et al, 2003;Tsvetanova et al, 2012). Protein kinases Src, aPKC, and Scyl1 have been implicated in COPI function at the level of the IC (Tisdale and Artalejo, 2006;Hamlin et al, 2014) and PKC and its downstream effectors appear to control IC morphology (Ben-Tekaya et al, 2010;Sugawara et al, 2012). The activation of neuronal Trk receptor tyrosine kinases in the IC initiates signaling via the MEK pathway leading to Golgi fragmentation (Schecterson et al, 2010).…”