Gβ1γ2 activates phospholipase A2-dependent Golgi membrane tubule formation

Abstract

Heterotrimeric G proteins transduce the ligand binding of transmembrane G protein coupled receptors into a variety of intracellular signaling pathways. Recently, heterotrimeric Gβγ subunit signaling at the Golgi complex has been shown to regulate the formation of vesicular transport carriers that deliver cargo from the Golgi to the plasma membrane. In addition to vesicles, membrane tubules have also been shown to mediate export from the Golgi complex, which requires the activity of cytoplasmic phospholipase A2 (PLA2) enzyme activity. Through the use of an in vitro reconstitution assay with isolated Golgi complexes, we provide evidence that Gβ1γ2 signaling also stimulates Golgi membrane tubule formation. In addition, we show that an inhibitor of Gβγ activation of PLA2 enzymes inhibits in vitro Golgi membrane tubule formation. Additionally, purified Gβγ protein stimulates membrane tubules in the presence of low (sub-threshold) cytosol concentrations. Importantly, this Gβγ stimulation of Golgi membrane tubule formation was inhibited by treatment with the PLA2 antagonist ONO-RS-082. These studies indicate that Gβ1γ2 signaling activates PLA2 enzymes required for Golgi membrane tubule formation, thus establishing a new layer of regulation for this process.

Sonic Hedgehog Activates Phospholipase A2 to Enhance Smoothened Ciliary Translocation

“…cPLA2α can be activated by recruitment to membranes, Ca 2+ flux, activation of Gα i or Gα o -coupled GPCRs, direct Gβγ binding, or through phosphorylation by cAMP-dependent protein kinase (PKA), PKC or Erk1/2 (Bechler and Brown, 2014; Murakami et al, 2011). Smo is a GPCR that couples to Gα i βγ heterotrimeric G proteins (Riobo et al, 2006), leading us to hypothesize Smo-dependent cPLA2α activation involved Smo-activated Gβγ.…”

Multi-omics analysis reveals that linoleic acid metabolism is associated with variations of trained immunity induced by distinct BCG strains

“…8, J to L). In contrast, the PLA2 inhibitors, ONO-RS-082 (ONO) and 1-naphthylacetic acid (NAA) ( 32 , 33 ), significantly attenuated BCG-induced trained immunity (Fig. 8, M to O).…”

Ca2+ regulation of constitutive vesicle trafficking

“…Three specific PLA 2 enzymes have been implicated in tubule regulation at the Golgi 85 – 87 , including cPLA 2 α 88 . Whereas cPLA 2 α is Ca 2+ activated, the other two Golgi-associated PLAs are not but could instead be activated by G protein βγ complexes 89 . Notably, cPLA 2 α is specifically recruited to the Golgi complex, likely via its C2 domain 90 , in response to transient increases in Ca 2+ apparently initiated by the arrival of secretory cargo 88 .…”