Okadaic acid treatment leads to a fragmentation of the trans-Golgi network and an increase in expression of TGN38 at the cell surface.
Okadaic acid (OA) is a protein phosphatase inhibitor which has, among other properties, previously been shown to induce a fragmentation of the cisternae of the Golgi stack [for review, see Lucocq (1992) J. Cell Sci. 103, 875-880]. The effects of OA an reversible and mimic intracellular events which occur during mitosis. To date, due to a lack of endogenous marker proteins, the effects of OA on the trans-Golgi network (TGN) has not been studied. Certain drugs, e.g. Brefeldin A (BFA), have different effects on the morphology of the Golgi stack and the TGN; it is therefore relevant to ask what effect(s) OA has on the TGN. We now present data from a study in which we have used antibodies to TGN38, an integral membrane protein predominantly localized to the TGN of rat NRK cells [Luzio, Brake, Banting, Howell, Braghetta and Stanley (1990) Biochem. J. 270, 97-102], to investigate the effects of OA on this organelle. OA induces a reversible fragmentation of the TGN. This fragmentation occurs with similar kinetics to that observed within the Golgi stack, and is independent of protein synthesis. The sensitivity of the TGN to OA is similar to that of the Golgi stack. The fragmentation of the TGN induced by OA also leads to a 10-fold increase in the level of TGN38 expressed at the plasma membrane.
Department of Biochemistry, School of Medical Sciences, University of Bristol, U.K.
M
M
Horn
G
G
Banting
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004988:Ethers, Cyclic / Q000494:pharmacology*; D005455:Fluorescent Antibody Technique; D006023:Glycoproteins; D006056:Golgi Apparatus / Q000187:drug effects* / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D019319:Okadaic Acid; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D051381:Rats
D004988:Ethers, Cyclic; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010446:Peptide Fragments; C513045:Tgoln2 protein, rat; D019319:Okadaic Acid; D003513:Cycloheximide