Golgi organization and stress sensing

Suchismita Chandran, Carolyn Machamer

Research output: Chapter in Book/Report/Conference proceedingChapter


The eukaryotic Golgi complex plays a central role in processing and sorting of cargoin the secretory pathway. The mammalian Golgi apparatus is composed of multiplestacks of cisternal membranes that are organized laterally into a ribbon-like structure at ajuxtanuclear location. The stacks are polarized and protein cargo moves through theorganelle in a cis-to-trans direction. In addition, trans-Golgi membranes come in closeapposition with specialized endoplasmic reticulum (ER) membranes. These contacts arebelieved to mediate lipid transfer from the ER directly to the trans-Golgi. The Golgiribbon structure is unique to vertebrate cells as lower eukaryotic cells lack this elaboratearchitecture. The complexity of the Golgi ribbon is intriguing and suggests potentialadditional functions. In this chapter, we discuss the structure of the mammalian Golgiribbon and its potential role as a sensor of cellular stress. We focus on the role of Golgiorganization in ceramide trafficking. Ceramide is a potent secondary messenger insignaling and apoptosis, and its levels are tightly regulated in cells. A protein calledCERT (ceramide transfer protein) delivers ceramide from its site of synthesis in the ER tothe trans-Golgi for sphingomyelin (SM) synthesis. CERT interacts with both ER andGolgi membranes, and may function at the ER-trans-Golgi contact sites. Some Golgistructural perturbations reduce SM synthesis as well as CERT's colocalization with Golgimarkers, suggesting that the organization of the mammalian Golgi ribbon together withCERT may promote specific ER-Golgi interactions for efficient delivery of ceramide forSM synthesis. Under cellular stress, caspase activation can lead to Golgi ribbondisassembly and loss of ER-trans-Golgi contact sites. Prolonged stress that cannot berepaired usually results in apoptosis. Interestingly, increased ceramide levels have beenassociated with apoptosis, but it is not yet known if newly synthesized ceramide resultingfrom perturbation of ER-trans-Golgi contact sites contributes to ceramide signalingduring apoptosis. An important question is whether ER-trans-Golgi contact sites areupstream targets of stress signals leading to increased ceramide levels and caspaseactivation, or if altered ceramide trafficking is downstream of Golgi disassembly.Regardless, it is clear that Golgi ribbon structure, including ER-trans-Golgi contact sites is exquisitely sensitive to perturbation, making this organelle an ideal platform to sensecellular stress and integrate signals that determine cell survival or cell death.

Original languageEnglish (US)
Title of host publicationGolgi Apparatus
Subtitle of host publicationStructure, Functions and Mechanisms
PublisherNova Science Publishers, Inc.
Number of pages41
ISBN (Print)9781611220513
StatePublished - Feb 2011

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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