Fas-activated serine/threonine kinase: Structure and function

Multi-omics Analysis of Prognostic Significance and Immune Infiltration of FASTK Family Members in Kidney Renal Clear Cell Carcinoma

Objective

The Fas-activated serine/threonine kinase (FASTK) family of proteins has been recently found to be able to regulate mitochondrial gene expression post-transcriptionally. Nonetheless, there is a paucity of study about the role of the FASTK family in kidney renal clear cell carcinoma (KIRC). This study was conducted to explore the correlation of FASTK family genes with expression, prognosis, and immune infiltration in KIRC.

Methods

We collected the data from the UALCAN, GeneMANIA, STRING, CancerSEA, cBioPortal, Kaplan-Meier plotter, GEPIA, TISIDB and TIMER databases to evaluate the genetic alterations, differential expression, prognostic significance, and immune cell infiltration of FASTKs in patients with KIRC.

Results

In tumor tissues of KIRC, the mRNA expression level of FASTK and TBRG4 was elevated, whereas that of FASTKD1, FASTKD2, and FASTKD5 was lowered compared with normal tissues (P < .05). Patients with KIRC and high FASTK and Transforming growth factor β regulator 4 (TBRG4) expression had worse overall survival (OS) and disease specific survival (DFS), while those with lower expression of FASTKD2/3/5 had worse outcomes. FASTK was positively correlated with DNA damage. FASTKD1 was positively related to differentiation. FASTKD2 was inversely related to proliferation and FASTKD5 was inversely related to invasion and EMT in KIRC cells. FASTK expression in KIRC was inversely linked to the presence of several immune cells including Tgd, macrophages, Tcm, and Mast cells (P < .05).

Conclusions

Our research provided fresh insight and in-depth analysis to the selection of prognostic biological markers of FASTK family members in KIRC.

Expedition of sulfur-containing heterocyclic derivatives as cytotoxic agents in medicinal chemistry: A decade update

This review article proposes a comprehensive report of the design strategies engaged in the development of various sulfur-bearing cytotoxic agents. The outcomes of various studies depict that the sulfur heterocyclic framework is a fundamental structure in diverse synthetic analogs representing a myriad scope of therapeutic activities. A number of five-, six- and seven-membered sulfur-containing heterocyclic scaffolds, such as thiazoles, thiadiazoles, thiazolidinediones, thiophenes, thiopyrans, benzothiazoles, benzothiophenes, thienopyrimidines, simple and modified phenothiazines, and thiazepines have been discussed. The subsequent studies of the derivatives unveiled their cytotoxic effects through multiple mechanisms (viz. inhibition of tyrosine kinases, topoisomerase I and II, tubulin, COX, DNA synthesis, and PI3K/Akt and Raf/MEK/ERK signaling pathways), and several others. Thus, our concise illustration explains the design strategy and anticancer potential of these five- and six-membered sulfur-containing heterocyclic molecules along with a brief outline on seven-membered sulfur heterocycles. The thorough assessment of antiproliferative activities with the reference drug allows a proficient assessment of the structure-activity relationships (SARs) of the diversely synthesized molecules of the series.

Accelerated FASTK mRNA degradation induced by oxidative stress is responsible for the destroyed myocardial mitochondrial gene expression and respiratory function in alcoholic cardiomyopathy

Chronic alcoholism disrupts mitochondrial function and often results in alcoholic cardiomyopathy (ACM). Fas-activated serine/threonine kinase (FASTK) is newly recognized as a key post-transcriptional regulator of mitochondrial gene expression. However, the modulatory role of FASTK in cardiovascular pathophysiology remains totally unknown. In experimental ACM models, cardiac FASTK expression markedly declined. Ethanol directly suppressed FASTK expression at post-transcriptional level through NADPH oxidase-derived reactive oxygen species (ROS). Ethanol destabilized FASTK mRNA 3'-untranslated region (3'-UTR) and accelerated its decay, which was blocked by the clearance of ROS. Regnase-1 (Reg1), a ribonuclease regulating mRNA stability, was induced by ROS in ethanol-stimulated cardiomyocytes. Reg1 directly bound to FASTK mRNA 3'-UTR and promoted its degradation, whereas silencing of Reg1 reversed ethanol-induced FASTK downregulation. Compared to wild type control, alcohol-related myocardial morphological (hypertrophy, fibrosis and cardiomyocyte apoptosis) and functional (reduced ejection fraction and compromised cardiomyocyte contraction) anomalies were worsened in FASTK deficient mice. Mechanistically, FASTK ablation repressed NADH dehydrogenase subunit 6 (MTND6, a mitochondrial gene encoding a subunit of complex I) mRNA production and reduced complex I-supported respiration. Importantly, cardiomyocyte-specific upregulation of FASTK through intra-cardiac AAV9-cTNT injection mitigated myocardial mitochondrial dysfunction and restrained ACM progression. In vitro study showed that overexpression of FASTK ameliorated ethanol-induced MTND6 mRNA downregulation, complex I inactivation, and cardiomyocyte death, whereas these beneficial effects were counteracted by rotenone, a complex I inhibitor. Collectively, ROS-accelerated FASTK mRNA degradation via Reg1 underlies chronic ethanol ingestion-associated mitochondrial dysfunction and cardiomyopathy. Restoration of FASTK expression through genetic approaches might be a promising therapeutic strategy for ACM.

Unravelling the unfolding pathway of human Fas-activated serine/threonine kinase induced by urea

Fas-activated serine/threonine kinase (FASTK) is a mitochondria-associated nuclear protein that inhibits Fas- and UV-induced apoptosis. This protein is generally activated during Fas-mediated apoptosis by phosphorylating a nuclear RNA-binding protein T-cell intracellular antigen-1 and thus considered as a modulator of apoptosis. In the present study, we have examined the equilibrium unfolding and conformational stability of the kinase domain of FASTK (FASTK_353-444). The kinase domain of FASTK_353-444 was cloned, expressed, and purified. The folding ↔ unfolding transitions of urea-induced denaturation was monitored with the help of circular dichroism, intrinsic fluorescence, and UV absorption spectroscopies. Analysis of transition curves obtained from different probes revealed a coincidence of denaturation curves, suggesting that folding/unfolding of FASTK follows a two-state process with the midpoint (C_m) value at 3.50 ± 0.1 M. Urea-induced denaturation curves were further analyzed to estimate change in the Gibbs free energy in the absence of urea (ΔG_D⁰) associated with the equilibrium of denaturation. To get atomistic insights into the urea-induced denaturation of FASTK, we performed an all-atom molecular dynamics simulation for 100 ns. A close agreement was noticed between experimental and computational studies. This study will help to understand the unfolding mechanism and structural stability of the kinase domain of FASTK.Communicated by Ramaswamy H. Sarma.

Thienopyrimidine-Chalcone Hybrid Molecules Inhibit Fas-Activated Serine/Threonine Kinase: An Approach To Ameliorate Antiproliferation in Human Breast Cancer Cells

Apoptotic evasion by cancerous cells being one of the striking hallmarks of cancer has turned into a new arena of drug discovery. A large number of pathways reported that govern the apoptotic evasion have been reported. Fas-activated serine/threonine kinase (FASTK) is a member of Ser/Thr kinase family, and it has been implicated in the apoptotic evasion and, hence, the development of cancer. Keeping this in view, a series of novel thienopyrimidine-based chalcones have been synthesized and evaluated to modulate the FASTK mediated apoptotic evasion. Initial screening was done by enzyme inhibition assay and binding studies, which showed that out of 15 synthesized compounds, 3 thienopyrimidine-based chalcone derivatives possess considerably high binding affinity and enzyme inhibitory potential (nM range) for FASTK. Cell proliferation assessment of selected compounds was performed on HEK-293 and MCF-7 cells. For MCF-7 cells, compounds 2, 10, and 12 show IC₅₀ values of 20.22 ± 1.50, 6.52 ± 0.82, and 8.20 ± 0.61 μM, respectively. Annexin-V and PI staining suggested that these molecules induce apoptosis in MCF-7 cells, arrest the cell cycle in the G0/G1 phase, and subsequently inhibit cell migration presumably by inhibiting FASTK and reactive oxygen species production. In conclusion, we have successfully designed, synthesized, and characterized thienopyrimidine-based chalcones that inhibit FASTK and induce apoptosis. These compounds may be exploited as potential anticancer agents.