Tongjin Zhao's research group revealed a sorting mechanism of palmitoylation modification-mediated proteins from the Golgi apparatus to cell membranes and proposed a method to inhibit EGFR-dependent tumor growth...

Epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor, and its overactivation caused by EGFR overexpression or mutation is the driving force of a variety of tumors, including lung cancer and breast cancer [1-2].

。 At present, EGFR-specific tyrosine kinase inhibitors (TKIs) and monoclonal antibodies are effective strategies for targeting EGFR-mutant cancers, but they are prone to acquired resistance during treatment and are not very effective in EGFR-overexpressed tumors [1].

New strategies need to be developed to target tumors
with EGFR overexpression or acquired mutations.

Protein palmitoylation is a reversible protein post-translational modification, which is a type of protein lipoacylation modification, mainly refers to the transfer of palmitoyl groups (C16:0) to cysteine residues of proteins in the form of sulfur lipid bonds
.
This reaction is catalyzed by a class of enzymes whose active centers contain the Asp-His-His-Cys (DHHC) motif, hence the name DHHC family [3].

A growing body of research has found that palmitoylation can act as a sorting signal to direct proteins to specific membrane structures, but the sorting mechanism is not well understood
.
Tongjin Zhao's research group has long studied the regulatory effect of protein palmitation modification on body function, and found that palmitation modification mediates the targeted sorting of fatty acid transposase CD36 to cell membranes (Cell Reports, 2019)[4], and dynamic palmitation modification regulates CD36 endocytosis-mediated fatty acid uptake (Nature Communications, 2020)[5].

EGFR is also a palmitoylated protein, although the palmitoylation site and corresponding DHHC enzyme differ in different reports [6,7].

Whether palmitoylation modifications affect EGFR-targeted sorting to cell membranes is unclear
.

On October 12, 2022, the Guo Huiling Experimental Group of the School of Life Sciences of Xiamen University and the Zhao Tongjin Research Group of the Institute of Metabolic and Integrative Biology of Fudan University jointly published a study entitled Targeting EGFR-dependent tumors by disrupting an ARF6-mediated sorting system in Nature Communications A sorting mechanism of palmitoylation modification-mediated proteins from the Golgi apparatus to cell membranes was revealed, and an effective strategy
for inhibiting EGFR-dependent tumor growth was also proposed.

The authors found that palmitoylation modification of EGFR by DHHC13 is critical for EGFR-targeting of cell membranes, and found that ARF6 is a key small GTPase
mediating palmitoylated EGFR targeting to cell membranes 。 The authors used the RUSH (Retention using selective hook) system, in situ adjacent fluorescence assay (PLA), DSP cross-linking immunoprecipitation experiment to find that ARF6 was recognized by N-terminal myristoylation modification binding to palmitoylated EGFR, ARF6 recruited Exocyst complex through N-terminal Lys3 to bind to it, and was further activated by EFA6B.
Facilitates the sorting of vesicles into the cell membrane in the form of GTP (Figure 1).

Figure 1.
ARF6 mediates the sorting of palmitoylated EGFR

On this basis, the authors designed a membrane-permeable peptide Myr-GKVL-TAT and found that it can effectively inhibit tumor growth in EGFR overexpression (Figure 2).

Figure 2.
Myr-GKVL-TAT interferes with ARF6-mediated palmitoylated EGFR sorting to inhibit tumor growth

This study revealed the important mechanism of ARF6-Exocyst mediating palmitoylation proteins from the Golgi apparatus to cells, found the important role of fatty acylation modifications, and proposed a new strategy
to inhibit tumor growth with high expression of EGFR.

Guo Huiling, assistant professor of the School of Life Sciences, Xiamen University, Wang Juan, young associate researcher of the Institute of Metabolic and Integrative Biology, Fudan University, Ren Shu and Zheng Langfan, doctoral students are the co-first authors of the paper, and Professor Zhao Tongjin of the Institute of Metabolic and Integrative Biology, Fudan University is the corresponding author
of the study.
This work was strongly supported
by Wang Hongrui's research group and Deng Xianming's research group at the School of Life Sciences, Xiamen University, and Li Peng's research group at the Institute of Metabolic and Integrative Biology of Fudan University.

Links to papers: https://doi.
org/10.
1038/s41467-022-33788-7

References

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   Pharmacol Res, 79, 34-74(2014)

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4. Juan Wang, Jian-Wei Hao, Xu Wang et al, DHHC4 and DHHC5 Facilitate Fatty Acid Uptake by Palmitoylating and Targeting CD36 to the Plasma Membrane.
   Cell Reports.
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5. Jian-Wei Hao, Juan Wang, Huiling Guo et al,CD36 facilitates fatty acid uptake by dynamic palmitoylation-regulated endocytosis.
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   Inhibition of DHHC20-Mediated EGFR Palmitoylation Creates a Dependence on EGFR Signaling.
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   Fatty acid synthase mediates EGFR palmitoylation in EGFR mutated non-small cell lung cancer.
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