ARL4A acts with GCC185 to modulate Golgi complex organization

Abstract

Summary ADP-ribosylation factor-like protein 4A (ARL4A) is a developmentally regulated member of the ARF/ARL GTPase family. The primary structure of ARL4A is very similar to that of other ARF/ARL molecules, but its function remains unclear. The trans-Golgi network golgin GCC185 is required for maintenance of Golgi structure and distinct endosome-to-Golgi transport. We show here that GCC185 acts as a new effector for ARL4 to modulate Golgi organization. ARL4A directly interacts with GCC185 in a GTP-dependent manner. Sub-coiled-coil regions of the CC2 domain of GCC185 are required for the interaction between GCC185 and ARL4A. Depletion of ARL4A reproduces the GCC185-depleted phenotype, causing fragmentation of the Golgi compartment and defects in endosome-to-Golgi transport. GCC185 and ARL4A localize to the Golgi independently of each other. Deletion of the ARL4A-interacting region of GCC185 results in inability to maintain Golgi structure. Depletion of ARL4A impairs the interaction between GCC185 and cytoplasmic linker-associated proteins 1 and 2 (CLASP1 and CLASP2, hereafter CLASPs) in vivo, and abolishes the GCC185-mediated Golgi recruitment of these CLASPs, which is crucial for the maintenance of Golgi structure. In summary, we suggest that ARL4A alters the integrity of the Golgi structure by facilitating the interaction of GCC185 with CLASPs.

Golgi as an MTOC: making microtubules for its own good

“…It is possible that a small GTPase Arl4a is involved in this regulation because it modulates recruitment of CLASPs to GCC185 at the TGN membrane (Lin et al 2011). Also, MT formation at the Golgi is tightly regulated by the cell cycle signaling: extensive nucleation throughout interphase and prophase is sharply down-regulated when a cell enters prometaphase, and starts to increase again in telophase (Maia et al 2013).…”

Cell cycle regulation of Golgi membrane dynamics

“…GCC185 was also shown to recruit microtubule +end binding proteins CLASPs to the TGN, which is required for Golgi-derived microtubule formation and Golgi ribbon integrity 74 . ARL4A, an Arf/Arl family protein, is shown to interact with GCC185 and regulate GCC185-mediated recruitment of CLASPs 75 .…”

“…Two cis -golgins, GM130 (through AKAP450) 77 and GMAP210 78, 79 , anchor γ-tubulin complexes to the cis -side of the Golgi complex. Golgi-derived microtubules need to be stabilized by CLASPs (CLASP1/2) that are tethered to trans -Golgi membranes through trans -golgin GCC185 74, 75 . In addition, CAP350 and Hook3 may be involved in microtubule stabilization on the Golgi 80, 81 .…”

Reduction in Golgi apparatus dimension in the absence of a residential protein, N-acetylglucosaminyltransferase V

“…Golgi reassembly stacking proteins (Barr et al 1997; Feinstein and Linstedt 2008; Puthenveedu et al 2006; Sengupta et al 2009; Shorter et al 1999; Xiang and Wang 2010), a cis Golgi matrix protein, GM130 (Lowe et al 1998; Marra et al 2007; Nakamura et al 1995, 1997), an NSF-like ATPase, p97, and NSF together with SNAPs and p115, a vesicle docking protein (Nelson et al 1998; Rabouille et al 1995b, 1998), seem to be important for the formation of the cisternal stack. In interphase cells, proteins cycling between the endoplasmic reticulum and the Golgi apparatus, such as Rab1b (Haas et al 2007; Monetta et al 2007; Romero et al 2013; Tomas et al 2012; Wilson et al 1994), Arf1 (Boal et al 2010; Lin et al 2011; Manolea et al 2008; Zhang et al 1994) and TAP/p115 (Nelson et al 1998; Puthenveedu and Linstedt 2001; Radulescu et al 2011), are involved in maintaining Golgi apparatus morphology. Furthermore, the spectrin membrane skeleton (Nelson et al 1998) is required for Golgi apparatus architecture.…”