The Function of the Golgi Ribbon Structure – An Enduring Mystery Unfolds!

Abstract

The Golgi apparatus in vertebrate cells consists of individual Golgi stacks fused together in a continuous ribbon structure. The ribbon structure per se is not required to mediate the classical functions of this organelle and the relevance of the "ribbon" structure has been a mystery since first identified ultrastructurally in the 1950s. Recent advances recognize a role for the Golgi apparatus in a range of cellular processes, some mediated by signaling networks which are regulated at the Golgi. Here we review the cellular processes and signaling events regulated by the Golgi apparatus and, in particular, explore an emerging theme that the ribbon structure of the Golgi contributes directly to the regulation of these higher order functions.

More than just sugars: Conserved oligomeric Golgi complex deficiency causes glycosylation‐independent cellular defects

“…Golgi fragmentation has also been observed to proceed apoptosis, alter cell migration and impair polarized secretion . Persistent fragmentation has been noted pathological states, such as cancers (eg, GOLPH3 is a well‐known oncogene, and its overexpression in cancer cells has been linked to Golgi fragmentation and enhanced cell proliferation), pathogenic infection (eg, Chlamydia remodels the Golgi in later stages on infection) and neurological diseases (Golgi fragmentation has been observed in Alzheimer's disease, ALS, Parkinsons and Creutzfeldt‐Jacob disease). Fragmentation of the Golgi in cancer has been theorized to proceed cancer cells becoming more metastatic .…”

Form and function of the Golgi apparatus: scaffolds, cytoskeleton and signalling

“…Moreover, a variety of signalling pathways have been reported to influence Golgi structure and function, including mTOR, MAPK, PTEN, Src, Hck, PKA/cAMP, ERK signalling [4,143]. The evolution of the Golgi ribbon in higher eukaryotes has been proposed to provide a platform for additional regulation of complex signalling networks compared with lower eukaryotes [28]. As mentioned previously, a relationship between signalling pathways and Golgi morphology was revealed by a genome wide kinome and phosphatome screen which identify 150 signalling genes which dramatically influenced the morphology of the Golgi, either inducing fragmentation or compaction [35].…”

“…A Golgi ribbon is a typical feature of cells during interphase which is then disassembled during mitosis into a collection of vesicles and tubules to allow partitioning of Golgi membranes between the two daughter cells [27]. The view of a Golgi ribbon as a static structure is likely to be overly simplistic and it has been proposed that the Golgi may be in a dynamic balance between mini-stacks and the ribbon [28]. Indeed, there are examples associated with differentiation programs where the Golgi ribbon is fragmented to individual Golgi stacks without loss of function.…”

Golgipathies in Neurodevelopment: A New View of Old Defects

“…A distinctive characteristic of the GA in the cells of mammals and other vertebrates is its structure -it is made up of stacks of flattened cisternae, as in protists, plants and invertebrates, but these stacks are linked to each other to form a "ribbon" [172,173]. Cisternal stacking is necessary for normal trafficking, while the ribbon structure is thought to play a role in higher order functions such as mitosis and apoptosis, cell polarity/migration and stress responses (reviewed in [174,175] through their interactions with other polarity-determining kinases as well as their role in microtubule nucleation and organization [179][180][181][182], dictate the polarity of the GA and thus of the cell or neuron as a whole [183], thus controlling its correct differentiation and function. The fragmentation of the GA ribbon through the phosphorylation of the GRASPs and other molecules might also allow GA repositioning and thus migration, growth or differentiation [184] (fragmentation is also essential for the progression of the cell cycle, discussed below).…”