The Cellular Senescence-Inhibited Gene Is Essential for PPM1A Myristoylation To Modulate Transforming Growth Factor β Signaling

TGF‑β/Smad signaling in chronic kidney disease: Exploring post‑translational regulatory perspectives (Review)

The TGF‑β/Smad signaling pathway plays a pivotal role in the onset of glomerular and tubulointerstitial fibrosis in chronic kidney disease (CKD). The present review delves into the intricate post‑translational modulation of this pathway and its implications in CKD. Specifically, the impact of the TGF‑β/Smad pathway on various biological processes was investigated, encompassing not only renal tubular epithelial cell apoptosis, inflammation, myofibroblast activation and cellular aging, but also its role in autophagy. Various post‑translational modifications (PTMs), including phosphorylation and ubiquitination, play a crucial role in modulating the intensity and persistence of the TGF‑β/Smad signaling pathway. They also dictate the functionality, stability and interactions of the TGF‑β/Smad components. The present review sheds light on recent findings regarding the impact of PTMs on TGF‑β receptors and Smads within the CKD landscape. In summary, a deeper insight into the post‑translational intricacies of TGF‑β/Smad signaling offers avenues for innovative therapeutic interventions to mitigate CKD progression. Ongoing research in this domain holds the potential to unveil powerful antifibrotic treatments, aiming to preserve renal integrity and function in patients with CKD.

PPM1A as a key target of the application of Jiawei‑Maxing‑Shigan decoction for the attenuation of radiation‑induced epithelial‑mesenchymal transition in type II alveolar epithelial cells

Radiation‑induced lung tissue injury is an important reason for the limited application of radiotherapy on thoracic malignancies. Previously, we reported that administration of Jiawei‑Maxing‑Shigan decoction (JMSD) attenuated the radiation‑induced epithelial‑mesenchymal transition (EMT) in alveolar epithelial cells (AECs) via TGF‑β/Smad signaling. The present study aimed to examine the role of protein phosphatase Mg²⁺/Mn²⁺‑dependent 1A (PPM1A) in the anti‑EMT activity of JMSD on AECs. The components in the aqueous extract of JMSD were identified by high‑performance liquid chromatography coupled with electrospray mass spectrometry. Primary rat type II AECs were treated with radiation (60Co γ‑ray at 8 Gy) and JMSD‑medicated serum. PPM1A was overexpressed and knocked down in the AECs via lentivirus transduction and the effects of JMSD administration on the key proteins related to TGF‑β1/Smad signaling were measured by western blotting. It was found that radiation decreased the PPM1A expression in the AECs and JMSD‑medicated serum upregulated the PPM1A expressions in the radiation‑induced AECs. PPM1A overexpression increased the E‑cadherin level but decreased the phosphorylated (p‑)Smad2/3, vimentin and α‑smooth muscle actin (α‑SMA) levels in the AECs. By contrast, the PPM1A knockdown decreased the E‑cadherin level and increased the p‑Smad2/3, vimentin and α‑SMA levels in the AECs and these effects could be blocked by SB431542 (TGF‑β1/Smad signaling inhibitor). JMSD administration increased the E‑cadherin level and decreased the p‑Smad2/3, vimentin and α‑SMA levels in the AECs; however, these effects could be blocked by siPPM1A‑2. In conclusion, PPM1A is a key target of JMSD administration for the attenuation of the radiation‑induced EMT in primary type II AECs via the TGF‑β1/Smad pathway.

A Not-So-Ancient Grease History: Click Chemistry and Protein Lipid Modifications

Protein lipid modification involves the attachment of hydrophobic groups to proteins via ester, thioester, amide, or thioether linkages. In this review, the specific click chemical reactions that have been employed to study protein lipid modification and their use for specific labeling applications are first described. This is followed by an introduction to the different types of protein lipid modifications that occur in biology. Next, the roles of click chemistry in elucidating specific biological features including the identification of lipid-modified proteins, studies of their regulation, and their role in diseases are presented. A description of the use of protein-lipid modifying enzymes for specific labeling applications including protein immobilization, fluorescent labeling, nanostructure assembly, and the construction of protein-drug conjugates is presented next. Concluding remarks and future directions are presented in the final section.

N-Myristoyltransferase as a Glycine and Lysine Myristoyltransferase in Cancer, Immunity, and Infections

Protein myristoylation, the addition of a 14-carbon saturated acyl group, is an abundant modification implicated in biological events as diverse as development, immunity, oncogenesis, and infections. N-Myristoyltransferase (NMT) is the enzyme that catalyzes this modification. Many elegant studies have established the rules guiding the catalysis including substrate amino acid sequence requirements with the indispensable N-terminal glycine, and a co-translational mode of action. Recent advances in technology such as the development of fatty acid analogs, small molecule inhibitors, and new proteomic strategies, allowed a deeper insight into the NMT activity and function. Here we focus on discussing recent work demonstrating that NMT is also a lysine myristoyltransferase, the enzyme's regulation by a previously unnoticed solvent channel, and the mechanism of NMT regulation by protein-protein interactions. We also summarize recent findings on NMT's role in cancer, immunity, and infections and the advances in pharmacological targeting of myristoylation. Our analyses highlight opportunities for further understanding and discoveries.