Kinases Phosphatases, Volume 2, Issue 3 (September 2024) – 6 articles

Angiogenesis is essential for remodeling and repairing existing vessels, and this process requires signaling pathways including those controlled by transforming growth factor beta (TGF-β). We have previously reported crosstalk between TGF-β and the protein kinase With No lysine (K) 1 (WNK1). Homozygous disruption of the gene encoding WNK1 results in lethality in mice near embryonic day E12 due to impaired angiogenesis, and this defect can be rescued by the endothelial-specific expression of an activated form of the WNK1 substrate kinase Oxidative Stress-Responsive 1 (OSR1). However, molecular processes regulated via a collaboration between TGF-β and WNK1/OSR1 are not well understood. Here, we show that WNK1 interacts with the E3 ubiquitin ligases SMURF1/2. In addition, we discovered that WNK1 regulates SMURF1/2 protein stability and vice versa. We also demonstrate that WNK1 activity regulates TGF-β receptor levels, in turn, controlling TGF-β signaling. Full article

Obesity has become a global epidemic, contributing to various metabolic diseases. Despite existing therapies, the need to investigate new molecular targets to combat obesity-associated pathologies persists. Glycogen Synthase Kinase-3 (GSK-3), a serine/threonine kinase with two paralogs (GSK-3α and GSK-3β), has emerged as a critical player in obesity-associated metabolic pathologies such as type 2 diabetes (T2D), and cardiovascular diseases (CVDs). However, its ubiquitous dynamic expression and complex context-dependent signaling pathways present challenges in understanding its precise role in metabolic perturbations. In the present review, we will highlight the specific role and the proposed mechanisms via which the two GSK-3 paralogs impact obesity-associated pathologies such as T2D, diabetic cardiomyopathy (DCM), and cognitive impairment, a hallmark of Alzheimer’s disease (AD). We will also highlight studies delineating the role of GSK-3s using either GSK-3 inhibitors or non-pharmacological compounds to inhibit/taper GSK-3 activity in metabolic diseases. Thus, the primary goal of this review is to highlight recent findings delineating the regulation/dysregulation of GSK-3α/β in tissues such as heart, liver, skeletal muscle, pancreas, brain, and adipose tissue that undergo morphological and metabolic changes with diet-induced obesity which predisposes obese individuals to numerous devastating chronic conditions by GSK-3 overactivity. Full article

ATM kinase is becoming an important therapeutic target for tumor radiosensitization. Radiation is known to cause neuro-inflammation and neurodegeneration; however, the effects of small molecule ATM inhibitors (ATMi’s) and radiation on normal tissue, including healthy brain, are largely unexplored. Therefore, we examined the mouse CNS after ATMi radiosensitization with a focus on the fate of neurons. We used several approaches to assess the effects on the DNA damage response (DDR) and apoptosis of neurons using immunostaining. In vivo, a significant decrease in viable neurons and increase in degenerating neurons and apoptosis was observed in mice treated with radiation alone. On the other hand, an ATMi alone had little to no effect on neuron viability and did not induce apoptosis. Importantly, the ATMi’s did not further increase radiation toxicity. In fact, multiplex immunostaining showed that a clinical candidate ATMi (AZD1390) protected mouse neurons from apoptosis by 90% at 4 h after radiation. We speculate that the lack of toxicity to neurons is due to a normal ATM–p53 response that, if blocked transiently with an ATMi, is protective. Altogether, in line with previous work using ATM knockout mice, we provide evidence that ATM kinase inhibition using small molecules does not add to neuronal radiation toxicity, and might, in fact, protect them from radiation-induced apoptosis at least in the short term. Full article

Cutaneous T-cell lymphomas (CTCLs) are a heterogeneous group of T-cell lymphomas characterised by high relapse rates and no curative treatments unless the allogeneic stem cell transplantation. The main complication in the management of this kind of malignancy is the variability that characterises the genetic and clinical features among the CTCL subtypes. JAK/STAT, MAPK/ERK, PI3K/Akt, and NF-kB are those signalling pathways that are found altered in CTCL and that are responsible for promoting both T-cell malignancy and the pro-tumorigenic microenvironment. Thus, targeting key players of these pathways can be an advantageous therapeutic option for CTCL. In this review, we aim to summarise the different approaches that precisely inhibit the kinases of each cited signalling. JAK inhibitors seem to be the most promising kinase inhibitors for CTCL. However, adverse events have been reported especially in patients with immunosuppression or an underlying autoimmune disease. More studies are needed, especially clinical trials, to investigate the benefits of these drugs for the treatment of cutaneous T-cell lymphomas. Full article

Copper is an essential heavy metal for diverse biological functions but toxic in excess. Consequently, a tightly regulated protein system is required to ensure adequate intracellular levels. In recent decades, several studies have explored the role of Cu⁺-ATPases in copper transport and homeostasis, revealing that these proteins are subject to kinase-mediated phosphorylation that significantly impacts their function. Techniques such as phosphoproteomic screening, site-directed mutagenesis, and artificial neural network tools demonstrated the regulatory effect of phosphorylation on these ATPases. Different protein kinases regulate Cu⁺-ATPases, modulating the active copper transport by affecting specific steps of the catalytic cycle, long-range intramolecular crosstalks, protein trafficking, gene expression, and protein stability. Therefore, the regulatory phosphorylation of Cu⁺-ATPases by kinases ultimately influences the intracellular copper distribution. This study aims to present a review of the scientific literature on the regulation of Cu⁺-ATPases by kinase-mediated phosphorylation as a crucial mechanism for copper homeostasis. This regulation offers new perspectives for developing therapies for disorders related to copper metabolism, such as Wilson and Menkes diseases, as well as cancer, diabetes mellitus, Parkinson’s, and Alzheimer’s diseases. These findings emphasize the need to further comprehend the signaling pathways involving protein kinases in the context of copper regulation. Full article

The phosphorylation state of 20 types of intracellular proteins in the presence of the protein phosphatase 1 (PP1)- and PP2A-specific Ser/Thr phosphatase inhibitor calyculin A or the Tyr phosphatase inhibitor pervanadate was visualized by Phos-tag SDS-PAGE followed by immunoblotting. All blots showed a Phos-tag pattern indicating increased phosphorylation in the presence of one or both phosphatase inhibitors. The increase in phosphorylation stoichiometry per protein tends to be greater for Ser/Thr phosphatase inhibition than for Tyr phosphatase inhibition. This is consistent with the fact that the number of Ser/Thr kinase genes in the human genome is greater than that of Tyr kinases and with the fact that the phospho-Ser/phospho-Thr ratio in the actual human phosphoproteome is far greater than that of phospho-Tyr ratio. This suggests that cellular proteins are routinely and randomly phosphorylated by different kinases with no biological significance, simply depending on the frequency of substrate encounters. Phosphatase is responsible for routinely removing these unwanted phosphate groups systematically and maintaining the dynamic equilibrium of physiological protein phosphorylation. Phos-tag SDS-PAGE visualized that the kinase reaction involves many incidental phosphorylation and that phosphatases play broader roles besides being strict counterparts to kinases. Full article