Does prenylation predict progression in NAFLD?

Alleviation of Hepatic Steatosis by 4-azidophlorizin via the Degradation of Geranylgeranyl Diphosphate Synthase by the Ubiquitin-Proteasome Pathway in Vivo and in Vitro

There are no known approved pharmacotherapies for non-alcoholic fatty liver disease (NAFLD) in the clinical setting. Although studies have provided substantial evidence that geranylgeranyl diphosphate synthase (GGPPS) is a potential therapeutic target for the treatment of NAFLD corresponding drug screening is rare. A GGPPS-targeted inhibitor is identified using a structure-based virtual small molecule screening method. The interaction of 4-AZ and GGPPS is detected by microscale thermophoresis. 4-AZ degradation of GGPPS by the ubiquitin-proteasome pathway is detected by western blotting. The anti-steatotic effect of 4-AZ in vivo is detected by CT. Lipid-related gene detection is detected by real-time PCR both in primary hepatocytes and mice. The compound inhibits the accumulation of lipids in primary hepatocytes and decreases lipogenic gene expression through GGPPS. Pharmacological studies show that 4-AZ can attenuate hepatic steatosis and improve liver injury in high-fat diet-induced mice. This data provides a novel application of 4-AZ NAFLD therapy, proving that the inhibition of GGPPS is a novel strategy for the treatment of NAFLD.

Regulation of protein prenylation

Prenyltransferases (PTases) are known to play a role in embryonic development, normal tissue homeostasis and cancer by posttranslationally modifying proteins involved in these processes. They are being discussed as potential drug targets in an increasing number of diseases, ranging from Alzheimer's disease to malaria. Protein prenylation and the development of specific PTase inhibitors (PTIs) have been subject to intense research in recent decades. Recently, the FDA approved lonafarnib, a specific farnesyltransferase inhibitor that acts directly on protein prenylation; and bempedoic acid, an ATP citrate lyase inhibitor that might alter intracellular isoprenoid composition, the relative concentrations of which can exert a decisive influence on protein prenylation. Both drugs represent the first approved agent in their respective substance class. Furthermore, an overwhelming number of processes and proteins that regulate protein prenylation have been identified over the years, many of which have been proposed as molecular targets for pharmacotherapy in their own right. However, certain aspects of protein prenylation, such as the regulation of PTase gene expression or the modulation of PTase activity by phosphorylation, have attracted less attention, despite their reported influence on tumor cell proliferation. Here, we want to summarize the advances regarding our understanding of the regulation of protein prenylation and the potential implications for drug development. Additionally, we want to suggest new lines of investigation that encompass the search for regulatory elements for PTases, especially at the genetic and epigenetic levels.

Knockout of GGPPS1 restrains rab37-mediated autophagy in response to ventilator-induced lung injury

Mechanical ventilation may cause ventilator-induced lung injury (VILI) in patients requiring ventilator support. Inhibition of autophagy is an important approach to ameliorate VILI as it always enhances lung injury after exposure to various stress agents. This study aimed to further reveal the potential mechanisms underlying the effects of geranylgeranyl diphosphate synthase large subunit 1 (GGPPS1) knockout and autophagy in VILI using C57BL/6 mice with lung-specific GGPPS1 knockout that were subjected to mechanical ventilation. The results demonstrate that GGPPS1 knockout mice exhibit significantly attenuated VILI based on the histologic score, the lung wet-to-dry ratio, total protein levels, neutrophils in bronchoalveolar lavage fluid, and reduced levels of inflammatory cytokines. Importantly, the expression levels of autophagy markers were obviously decreased in GGPPS1 knockout mice compared with wild-type mice. The inhibitory effects of GGPPS1 knockout on autophagy were further confirmed by measuring the ultrastructural change of lung tissues under transmission electron microscopy. In addition, knockdown of GGPPS1 in RAW264.7 cells reduced cyclic stretch-induced inflammation and autophagy. The benefits of GGPPS1 knockout for VILI can be partially eliminated through treatment with rapamycin. Further analysis revealed that Rab37 was significantly downregulated in GGPPS1 knockout mice after mechanical ventilation, while it was highly expressed in the control group. Simultaneously, Rab37 overexpression significantly enhances autophagy in cells that are treated with cyclin stretch, including GGPPS1 knockout cells. Collectively, our results indicate that GGPPS1 knockout results in reduced expression of Rab37 proteins, further restraining autophagy and VILI.