PIM1 Promotes Survival of Cardiomyocytes by Upregulating c-Kit Protein Expression

A review on structure-function mechanism and signaling pathway of serine/threonine protein PIM kinases as a therapeutic target

The proviral integration for the Moloney murine leukemia virus (PIM) kinases, belonging to serine/threonine kinase family, have been found to be overexpressed in various types of cancers, such as prostate, breast, colon, endometrial, gastric, and pancreatic cancer. The three isoforms PIM kinases i.e., PIM1, PIM2, and PIM3 share a high degree of sequence and structural similarity and phosphorylate substrates controlling tumorigenic phenotypes like proliferation and cell survival. Targeting short-lived PIM kinases presents an intriguing strategy as in vivo knock-down studies result in non-lethal phenotypes, indicating that clinical inhibition of PIM might have fewer adverse effects. The ATP binding site (hinge region) possesses distinctive attributes, which led to the development of novel small molecule scaffolds that target either one or all three PIM isoforms. Machine learning and structure-based approaches have been at the forefront of developing novel and effective chemical therapeutics against PIM in preclinical and clinical settings, and none have yet received approval for cancer treatment. The stability of PIM isoforms is maintained by PIM kinase activity, which leads to resistance against PIM inhibitors and chemotherapy; thus, to overcome such effects, PIM proteolysis targeting chimeras (PROTACs) are now being developed that specifically degrade PIM proteins. In this review, we recapitulate an overview of the oncogenic functions of PIM kinases, their structure, function, and crucial signaling network in different types of cancer, and the potential of pharmacological small-molecule inhibitors. Further, our comprehensive review also provides valuable insights for developing novel antitumor drugs that specifically target PIM kinases in the future. In conclusion, we provide insights into the benefits of degrading PIM kinases as opposed to blocking their catalytic activity to address the oncogenic potential of PIM kinases.

PIM1 attenuates cisplatin-induced AKI by inhibiting Drp1 activation

Cisplatin, an effective anti-cancer drug, always causes acute kidney injury (AKI) by inducing mitochondrial damage. PIM1 is a serine/threonine kinase, which has been shown to regulate mitochondrial function. However, the role and mechanisms of PIM1 in cisplatin-induced AKI remain unexplored. This study aimed to investigate the effects of PIM1 in cisplatin-induced AKI and its underlying mechanisms. To established Cisplatin-induced AKI model, mice were given a single intraperitoneal injection(20 mg/kg) and BUMPT cells were treated with cisplatin(20 μM). PIM1 inhibitor AZD1208 was used to inhibit PIM1 and PIM1-experssing adenovirus was used to overexpress PIM1. Drp1 inhibitor P110 and pcDNA3-Drp1K38A were used to inhibit the activation of Drp1 and mitochondrial fission. The indicators of renal function, renal morphology, apoptosis and mitochondrial dysfunction were assessed to evaluate cisplatin-induced nephrotoxicity. We observed that PIM1 was activated in cisplatin-induced AKI in vivo and cisplatin-induced tubular cells injury in vitro. PIM1 inhibition aggravated cisplatin-induced AKI in vivo, while PIM1 overexpression attenuated cisplatin-induced kidney injury in vivo and in vitro. Moreover, inhibiting PIM1 exacerbated mitochondrial damage in mice, but overexpressing PIM1 relieved mitochondrial damage in mice and BUMPT cells. In mice and BUMPT cells, inhibiting PIM1 deregulated the expression of p-Drp1S637, overexpressing PIM1 upregulated the ex-pression of p-Drp1S637. And inhibiting Drp1 activity alleviated cell damage in BUMPT cells with PIM1 knockdown or inhibition. This study demonstrated the protective effect of PIM1 in cisplatin-induced AKI, and regulation of Drp1 activation might be the underlying mechanism. Altogether, PIM1 may be a potential therapeutic target for cisplatin-induced AKI.

Pim Kinases: Important Regulators of Cardiovascular Disease

Pim Kinases; Pim-1, Pim-2, and Pim-3, are a family of constitutively active serine/threonine kinases, widely associated with cell survival, proliferation, and migration. Historically considered to be functionally redundant, independent roles for the individual isoforms have been described. Whilst most established for their role in cancer progression, there is increasing evidence for wider pathological roles of Pim kinases within the context of cardiovascular disease, including inflammation, thrombosis, and cardiac injury. The Pim kinase isoforms have widespread expression in cardiovascular tissues, including the heart, coronary artery, aorta, and blood, and have been demonstrated to be upregulated in several co-morbidities/risk factors for cardiovascular disease. Pim kinase inhibition may thus be a desirable therapeutic for a multi-targeted approach to treat cardiovascular disease and some of the associated risk factors. In this review, we discuss what is known about Pim kinase expression and activity in cells of the cardiovascular system, identify areas where the role of Pim kinase has yet to be fully explored and characterised and review the suitability of targeting Pim kinase for the prevention and treatment of cardiovascular events in high-risk individuals.

Genetics of myocardial interstitial fibrosis in the human heart and association with disease

Myocardial interstitial fibrosis is associated with cardiovascular disease and adverse prognosis. Here, to investigate the biological pathways that underlie fibrosis in the human heart, we developed a machine learning model to measure native myocardial T1 time, a marker of myocardial fibrosis, in 41,505 UK Biobank participants who underwent cardiac magnetic resonance imaging. Greater T1 time was associated with diabetes mellitus, renal disease, aortic stenosis, cardiomyopathy, heart failure, atrial fibrillation, conduction disease and rheumatoid arthritis. Genome-wide association analysis identified 11 independent loci associated with T1 time. The identified loci implicated genes involved in glucose transport (SLC2A12), iron homeostasis (HFE, TMPRSS6), tissue repair (ADAMTSL1, VEGFC), oxidative stress (SOD2), cardiac hypertrophy (MYH7B) and calcium signaling (CAMK2D). Using a transforming growth factor β1-mediated cardiac fibroblast activation assay, we found that 9 of the 11 loci consisted of genes that exhibited temporal changes in expression or open chromatin conformation supporting their biological relevance to myofibroblast cell state acquisition. By harnessing machine learning to perform large-scale quantification of myocardial interstitial fibrosis using cardiac imaging, we validate associations between cardiac fibrosis and disease, and identify new biologically relevant pathways underlying fibrosis.

Cardioprotective effect of crude polysaccharide fermented by Trametes Sanguinea Lyoyd on doxorubicin-induced myocardial injury mice

Doxorubicin (DOX) is a broad-spectrum anti-tumor drug, but its clinical application is greatly limited because of the cardiotoxicity. Thus, exploration of effective therapies against DOX-induced cardiotoxicity is necessary. The aim of this study is to investigate the effects and possible mechanisms of Trametes Sanguinea Lyoyd fermented crude polysaccharide (TSLFACP) against DOX-induced cardiotoxicity. We investigated the protective effects of TSLFACP on myocardial injury and its possible mechanisms using two in vitro cells of DOX-treated cardiomyocytes H9C2 and embryonic myocardial cell line CCC-HEH-2 and a in vivo mouse model of DOX-induced myocardial injury. We found that TSLFACP could reverse DOX-induced toxicity in H9C2 and CCC-HEH-2 cells. Similarly, we found that when pretreatment with TSLFACP (200 mg/kg, i.g.) daily for 6 days, DOX-induced myocardial damage was attenuated, including the decrease in serum myocardial injury index, and the amelioration in cardiac histopathological morphology. Additionally, immunohistochemistry and western blotting were used to identify the underlying and possible signal pathways. We found that TSLFACP attenuated the expression of LC3-II, Beclin-1 and PRAP induced by DOX. In conclusion, our results demonstrated that TSLFACP could protect against DOX-induced cardiotoxicity by inhibiting autophagy and apoptosis.

Dasatinib targets c-Src kinase in cardiotoxicity

Dasatinib is a multitargeted kinase inhibitor used for treatment of chronic myeloid leukemia and acute lymphoblastic leukemia. Unfortunately, treatment of cancer patients with some kinase inhibitors has been associated with cardiotoxicity. Cancer treatment with dasatinib has been reported to be associated with cardiotoxic side effects such as left ventricular dysfunction, heart failure, pericardial effusion and pulmonary hypertension. Here we aimed to investigate the molecular mechanisms underlying the cardiotoxicity of dasatinib. We found that among the resident cardiac cell types, cardiomyocytes were most sensitive to dasatinib-induced cell death. Exposure of cardiomyocytes to dasatinib attenuated the activity of extracellular signal-regulated kinase (ERK), which is a downstream target of dasatinib target kinase c-Src. Similar to dasatinib, c-Src depletion in cardiomyocytes compromised cardiomyocyte viability. Overexpression of dasatinib-resistant mutant of c-Src rescued the toxicity of dasatinib on cardiomyocytes, whereas forced expression of wild type c-Src did not have protective effect. Collectively, our results show that c-Src is a key target of dasatinib mediating the toxicity of dasatinib to cardiomyocytes. These findings may influence future drug design and suggest closer monitoring of patients treated with agents targeting c-Src for possible adverse cardiac effects.

Multicellular immune dynamics implicate PIM1 as a potential therapeutic target for uveitis

Uveitis is a severe autoimmune disease, and a common cause of blindness; however, its individual cellular dynamics and pathogenic mechanism remain poorly understood. Herein, by performing single-cell RNA sequencing (scRNA-seq) on experimental autoimmune uveitis (EAU), we identify disease-associated alterations in cell composition and transcriptional regulation as the disease progressed, as well as a disease-related molecule, PIM1. Inhibiting PIM1 reduces the Th17 cell proportion and increases the Treg cell proportion, likely due to regulation of PIM1 to the protein kinase B (AKT)/Forkhead box O1 (FOXO1) pathway. Moreover, inhibiting PIM1 reduces Th17 cell pathogenicity and reduces plasma cell differentiation. Importantly, the upregulation of PIM1 in CD4⁺ T cells and plasma cells is conserved in a human uveitis, Vogt-Koyanagi-Harada disease (VKH), and inhibition of PIM1 reduces CD4⁺ T and B cell expansion. Collectively, a dynamic immune cellular atlas during uveitis is developed and implicate that PIM1 may be a potential therapeutic target for VKH.

Uveitis is a complex autoimmune inflammatory disease of the eye and defining molecules involved is a priority. Here the authors use scRNA sequencing in mouse experimental autoimmune uveitis (EAU) and show PIM1 promotes the imbalance of Th17 and Treg cells, and find elevated PIM-1 in human uveitis disease.

Cell-Based and Selected Cell-Free Therapies for Myocardial Infarction: How Do They Compare to the Current Treatment Options?

Because of cardiomyocyte death or dysfunction frequently caused by myocardial infarction (MI), heart failure is a leading cause of morbidity and mortality in modern society. Paradoxically, only limited and non-curative therapies for heart failure or MI are currently available. As a result, over the past two decades research has focused on developing cell-based approaches promoting the regeneration of infarcted tissue. Cell-based therapies for myocardial regeneration include powerful candidates, such as multipotent stem cells (mesenchymal stem cells (MSCs), bone-marrow-derived stem cells, endothelial progenitor cells, and hematopoietic stem cells) and induced pluripotent stem cells (iPSCs). These possess unique properties, such as potency to differentiate into desired cell types, proliferation capacity, and patient specificity. Preclinical and clinical studies have demonstrated modest improvement in the myocardial regeneration and reduced infarcted areas upon transplantation of pluripotent or multipotent stem cells. Another cell population that need to be considered as a potential source for cardiac regeneration are telocytes found in different organs, including the heart. Their therapeutic effect has been studied in various heart pathologies, such as MI, arrhythmias, or atrial amyloidosis. The most recent cell-free therapeutic tool relies on the cardioprotective effect of complex cargo carried by small membrane-bound vesicles-exosomes-released from stem cells via exocytosis. The MSC/iPSC-derived exosomes could be considered a novel exosome-based therapy for cardiovascular diseases thanks to their unique content. There are also other cell-free approaches, e.g., gene therapy, or acellular cardiac patches. Therefore, our review provides the most recent insights into the novel strategies for myocardial repair based on the regenerative potential of different cell types and cell-free approaches.

Dihydromyricetin ameliorates osteogenic differentiation of human aortic valve interstitial cells by targeting c-KIT/interleukin-6 signaling pathway

Aims: Calcific aortic valve disease (CAVD) is a chronic cardiovascular disease with high morbidity that lacks effective pharmacotherapeutics. As a natural flavonoid extracted from Ampelopsis grossedentata, dihydromyricetin (DHM) has been shown to be effective in protecting against atherosclerosis; yet, the therapeutic role of DHM in CAVD remains poorly understood. Herein, we aimed to clarify the therapeutic implications of DHM in CAVD and the underlying molecular mechanisms in human valvular interstitial cells (hVICs).

Methods and Results: The protein levels of two known osteogenesis-specific genes (alkaline phosphatase, ALP; runt-related transcription factor 2, Runx2) and calcified nodule formation in hVICs were detected by Western blot and Alizarin Red staining, respectively. The results showed that DHM markedly ameliorated osteogenic induction medium (OM)–induced osteogenic differentiation of hVICs, as evidenced by downregulation of ALP and Runx2 expression and decreased calcium deposition. The SwissTargetPrediction database was used to identify the potential AVC-associated direct protein target of DHM. Protein–protein interaction (PPI) analysis revealed that c-KIT, a tyrosine-protein kinase, can act as a credible protein target of DHM, as evidenced by molecular docking. Mechanistically, DHM-mediated inhibition of c-KIT phosphorylation drove interleukin-6 (IL-6) downregulation in CAVD, thereby ameliorating OM-induced osteogenic differentiation of hVICs and aortic valve calcification progression.

Conclusion: DHM ameliorates osteogenic differentiation of hVICs by blocking the phosphorylation of c-KIT, thus reducing IL-6 expression in CAVD. DHM could be a viable therapeutic supplement to impede CAVD.

'Youthful' phenotype of c-Kit+ cardiac fibroblasts

Cardiac fibroblast (CF) population heterogeneity and plasticity present a challenge for categorization of biological and functional properties. Distinct molecular markers and associated signaling pathways provide valuable insight for CF biology and interventional strategies to influence injury response and aging-associated remodeling. Receptor tyrosine kinase c-Kit mediates cell survival, proliferation, migration, and is activated by pathological injury. However, the biological significance of c-Kit within CF population has not been addressed. An inducible reporter mouse detects c-Kit promoter activation with Enhanced Green Fluorescent Protein (EGFP) expression in cardiac cells. Coincidence of EGFP and c-Kit with the DDR2 fibroblast marker was confirmed using flow cytometry and immunohistochemistry. Subsequently, CFs expressing DDR2 with or without c-Kit was isolated and characterized. A subset of DDR2+ CFs also express c-Kit with coincidence in ~ 8% of total cardiac interstitial cells (CICs). Aging is associated with decreased number of c-Kit expressing DDR2+ CFs, whereas pathological injury induces c-Kit and DDR2 as well as the frequency of coincident expression in CICs. scRNA-Seq profiling reveals the transcriptome of c-Kit expressing CFs as cells with transitional phenotype. Cultured cardiac DDR2+ fibroblasts that are c-Kit+ exhibit morphological and functional characteristics consistent with youthful phenotypes compared to c-Kit- cells. Mechanistically, c-Kit expression correlates with signaling implicated in proliferation and cell migration, including phospho-ERK and pro-caspase 3. The phenotype of c-kit+ on DDR2+ CFs correlates with multiple characteristics of 'youthful' cells. To our knowledge, this represents the first evaluation of c-Kit biology within DDR2+ CF population and provides a fundamental basis for future studies to influence myocardial biology, response to pathological injury and physiological aging.

Dual data and motif clustering improves the modeling and interpretation of phosphoproteomic data

Cell signaling is orchestrated in part through a network of protein kinases and phosphatases. Dysregulation of kinase signaling is widespread in diseases such as cancer and is readily targetable through inhibitors. Mass spectrometry-based analysis can provide a global view of kinase regulation, but mining these data is complicated by its stochastic coverage of the proteome, measurement of substrates rather than kinases, and the scale of the data. Here, we implement a dual data and motif clustering (DDMC) strategy that simultaneously clusters peptides into similarly regulated groups based on their variation and their sequence profile. We show that this can help to identify putative upstream kinases and supply more robust clustering. We apply this clustering to clinical proteomic profiling of lung cancer and identify conserved proteomic signatures of tumorigenicity, genetic mutations, and immune infiltration. We propose that DDMC provides a general and flexible clustering strategy for the analysis of phosphoproteomic data.

ERK1/2: An Integrator of Signals That Alters Cardiac Homeostasis and Growth

Integration of cellular responses to extracellular cues is essential for cell survival and adaptation to stress. Extracellular signal-regulated kinase (ERK) 1 and 2 serve an evolutionarily conserved role for intracellular signal transduction that proved critical for cardiomyocyte homeostasis and cardiac stress responses. Considering the importance of ERK1/2 in the heart, understanding how these kinases operate in both normal and disease states is critical. Here, we review the complexity of upstream and downstream signals that govern ERK1/2-dependent regulation of cardiac structure and function. Particular emphasis is given to cardiomyocyte hypertrophy as an outcome of ERK1/2 activation regulation in the heart.