A unique lysophospholipid acyltransferase (LPAT) antagonist, CI-976, affects secretory and endocytic membrane trafficking pathways

K Chambers, B Judson, WJ Brown - Journal of cell science, 2005 - journals.biologists.com
K Chambers, B Judson, WJ Brown
Journal of cell science, 2005journals.biologists.com
Previous studies have shown that inhibition of a Golgi-complex-associated lysophospholipid
acyltransferase (LPAT) activity by the drug CI-976 stimulates Golgi tubule formation and
subsequent redistribution of resident Golgi proteins to the endoplasmic reticulum (ER). Here,
we show that CI-976 stimulates tubule formation from all subcompartments of the Golgi
complex, and often these tubules formed independently, ie individual tubules usually did not
contain markers from different subcompartments. Whereas the cis, medial and trans Golgi …
Previous studies have shown that inhibition of a Golgi-complex-associated lysophospholipid acyltransferase (LPAT) activity by the drug CI-976 stimulates Golgi tubule formation and subsequent redistribution of resident Golgi proteins to the endoplasmic reticulum (ER). Here, we show that CI-976 stimulates tubule formation from all subcompartments of the Golgi complex, and often these tubules formed independently, i.e. individual tubules usually did not contain markers from different subcompartments. Whereas the cis, medial and trans Golgi membranes redistributed to the ER, the trans Golgi network (TGN) collapsed back to a compact juxtanuclear position similar to that seen with brefeldin A (BFA) treatment. Also similar to BFA, CI-976 induced the formation of endosome tubules, but unlike BFA, these tubules did not fuse with TGN tubules. Finally, CI-976 produced an apparently irreversible block in the endocytic recycling pathway of transferrin (Tf) and Tf receptors (TfRs) but had no direct effect on Tf uptake from the cell surface. Tf and TfRs accumulated in centrally located, Rab11-positive vesicles indicating that CI-976 inhibits export of cargo from the central endocytic recycling compartment. These results, together with previous studies, demonstrate that CI-976 inhibits multiple membrane trafficking steps, including ones found in the endocytic and secretory pathways, and imply a wider role for lysophospholipid acyltransferases in membrane trafficking.
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