SARS-CoV-2 hijacks a cell damage response, which induces transcription of a more efficient Spike S-acyltransferase

ZDHHC3-LYPLA1 regulates PRRSV-2 replication through reversible palmitoylation

Porcine reproductive and respiratory syndrome virus (PRRSV) is a highly contagious swine pathogen, causing respiratory problems in piglets and reproductive failure in sows. Palmitoylation, catalyzed by zinc finger Asp-His-His-Cys (ZDHHC) domain-containing palmitoyl acyltransferases, plays intricate roles in virus infection. However, whether palmitoylation regulates PRRSV replication is incompletely understood. Here, we report that inhibition of palmitoylation by 2-bromo palmitate (2-BP) promotes PRRSV multiplication. ZDHHC3 is identified as the key palmitoyl transferase regulating PRRSV replication in PAMs infection. Mechanistically, ZDHHC3 catalyzes nucleocapsid (N) protein palmitoylation at cysteine 90. This modification prevents the Nsp9-N protein interaction and subsequent viral RNA synthesis. Furthermore, LYPLA1 de-palmitoylates N protein, thus counteracting the ZDHHC3's activity on PRRSV replication. Meanwhile, the administration of small-molecule inhibitor ML348 targeting LYPLA1 could hinder PRRSV-2 replication. In summary, our results underscore the critical role of reversible palmitoylation in PRRSV replication. These findings might provide potential new anti-PRRSV strategies.

ZDHHC20 mediated S-palmitoylation of fatty acid synthase (FASN) promotes hepatocarcinogenesis

BACKGROUND

Protein palmitoylation is a reversible fatty acyl modification that undertakes important functions in multiple physiological processes. Dysregulated palmitoylations are frequently associated with the formation of cancer. How palmitoyltransferases for S-palmitoylation are involved in the occurrence and development of hepatocellular carcinoma (HCC) is largely unknown.

METHODS

Chemical carcinogen diethylnitrosamine (DEN)-induced and DEN combined CCl4 HCC models were used in the zinc finger DHHC-type palmitoyltransferase 20 (ZDHHC20) knockout mice to investigate the role of ZDHHC20 in HCC tumourigenesis. Palmitoylation liquid chromatography-mass spectrometry analysis, acyl-biotin exchange assay, co-immunoprecipitation, ubiquitination assays, protein half-life assays and immunofluorescence microscopy were conducted to explore the downstream regulators and corresponding mechanisms of ZDHHC20 in HCC.

RESULTS

Knocking out of ZDHHC20 significantly reduced hepatocarcinogenesis induced by chemical agents in the two HCC mouse models in vivo. 97 proteins with 123 cysteine sites were found to be palmitoylated in a ZDHHC20-dependent manner. Among these, fatty acid synthase (FASN) was palmitoylated at cysteines 1471 and 1881 by ZDHHC20. The genetic knockout or pharmacological inhibition of ZDHHC20, as well as the mutation of the critical cysteine sites of FASN (C1471S/C1881S) accelerated the degradation of FASN. Furthermore, ZDHHC20-mediated FASN palmitoylation competed against the ubiquitin-proteasome pathway via the E3 ubiquitin ligase complex SNX8-TRIM28.

CONCLUSIONS

Our findings demonstrate the critical role of ZDHHC20 in promoting hepatocarcinogenesis, and a mechanism underlying a mutual restricting mode for protein palmitoylation and ubiquitination modifications.

Mechanisms and functions of protein S-acylation

Over the past two decades, protein S-acylation (often referred to as S-palmitoylation) has emerged as an important regulator of vital signalling pathways. S-Acylation is a reversible post-translational modification that involves the attachment of a fatty acid to a protein. Maintenance of the equilibrium between protein S-acylation and deacylation has demonstrated profound effects on various cellular processes, including innate immunity, inflammation, glucose metabolism and fat metabolism, as well as on brain and heart function. This Review provides an overview of current understanding of S-acylation and deacylation enzymes, their spatiotemporal regulation by sophisticated multilayered mechanisms, and their influence on protein function, cellular processes and physiological pathways. Furthermore, we examine how disruptions in protein S-acylation are associated with a broad spectrum of diseases from cancer to autoinflammatory disorders and neurological conditions.