Regulation of the Golgi Apparatus by p38 and JNK Kinases during Cellular Stress Responses

Abstract

p38 and c-Jun N-terninal kinase (JNK) are activated in response to acute stress and inflammatory signals. Through modification of a plethora of substrates, these kinases profoundly re-shape cellular physiology for the optimal response to a harmful environment and/or an inflammatory state. Here, we utilized phospho-proteomics to identify several hundred substrates for both kinases. Our results indicate that the scale of signaling from p38 and JNK are of a similar magnitude. Among the many new targets, we highlight the regulation of the transcriptional regulators grb10-interacting GYF protein 1 and 2 (GIGYF1/2) by p38-dependent MAP kinase-activated protein kinase 2 (MK2) phosphorylation and 14–3–3 binding. We also show that the Golgi apparatus contains numerous substrates, and is a major target for regulation by p38 and JNK. When activated, these kinases mediate structural rearrangement of the Golgi apparatus, which positively affects protein flux through the secretory system. Our work expands on our knowledge about p38 and JNK signaling with important biological ramifications.

Characterization of p38α signaling networks in cancer cells using quantitative proteomics and phosphoproteomics

“…Moreover, our work highlights the role of p38a in cancer cell adhesion and identifies ArgBP2 as a mediator of the p38a function in this process. PhosphositePlus (PSP) and potential p38a targets previously reported by (14) or (13) with the p38a downregulated phosphosites identified in our KO/WT dataset (KO) or PH/WT dataset (PH). G, identification of p38a-regulated proteins that interact with p38a and could be potential substrates.…”

“…C - E , Venn diagrams showing the numbers of proteins (C), phosphosites (D) and phosphoproteins ( E ) that overlap between KO/WT and PH/WT (FC>1.5 and p-value<0.05) and that are either downregulated (Down) or upregulated (Up). F , overlap of p38α substrates listed in PhosphositePlus (PSP) and potential p38α targets previously reported by (14) or (13) with the p38α downregulated phosphosites identified in our KO/WT dataset (KO) or PH/WT dataset (PH). G , identification of p38α-regulated proteins that interact with p38α and could be potential substrates.…”

“…Next, we compared the p38α-dependent phosphosites identified in p38α KO (53) or PH797804-treated cells (257) with previously known p38α substrates curated in the PhoshositePlus database (316) or reported in two phosphoproteomic studies (13,14) (82 in Borisova’s and 250 in Nordgaard’s) (Fig. 3F).…”

“…We have used high-resolution quantitative mass spectrometry to study the p38α-regulated signaling networks in proliferating breast cancer cells. Previous reports using similar approaches have focused on the p38α targets engaged by particular stresses such as UV and anisomycin in U2OS cells (13,14). However, p38α can integrate a variety of intracellular signals in normally proliferating cells (3).…”

“…Previous reports have investigated phosphorylation changes that are potentially controlled by p38 MAPKs in differentiating myoblasts and in early mouse embryos, as well as in U2OS cells treated with the stress stimuli UV or anisomycin. All these studies were based on the use of pyridyl imidazole inhibitors such as SB203580 (11)(12)(13)(14). However, to our knowledge, the phosphoproteome regulated by p38a in non-stressed mammalian cancer cells has not been characterized.…”