The Small Molecule Indirubin-3'-Oxime Inhibits Protein Kinase R: Antiapoptotic and Antioxidant Effect in Rat Cardiac Myocytes

Abstract

Double-stranded, RNA-dependent protein kinase R (PKR) is a serine/threonine protein kinase activated by various stress signals. It plays an important role in inflammation, insulin sensitivity and glucose homeostasis. Increased PKR activity has been observed in obese humans as well as in obese diabetic mice. Indirubin-3'-oxime (I3O) is an effective inhibitor of cyclin-dependent kinases and glycogen synthase kinase 3-beta. However, the effects of I3O on PKR activity/expression in cultured rat cardiomyocytes have not been reported. We investigated whether I3O attenuates the effects of high glucose on PKR, oxidative stress and apoptotic gene markers. Quantitative PCR and western blotting were used to measure protein and mRNA, respectively. High glucose treatment caused significant increase in the PKR protein/mRNA expression, which was attenuated by co-treatment with I3O. High glucose-treated, cultured cardiomyocytes developed a significant increase in mRNA expression for c-Jun-N-terminal kinase, caspase-3 and NF-κB, which were all attenuated by pretreatment with I3O. There was also a significant increase in reactive oxygen species generation in high glucose-treated, cultured cardiomyocytes, which was attenuated by pretreatment with I3O. In conclusion, I3O may have a preventive role against the deleterious effects of high glucose in the heart.

Crucial role of reactive oxygen species (ROS) for the proapoptotic effects of indirubin derivative DKP‐073 in melanoma cells

“…Thus, ROS levels induced by high glucose in rat cardiomyocytes or by LPS in brain microglia cells were diminished by indirubin-3′oxime. 46,47 The present work unravels the mechanism of DKP-073-induced apoptosis in melanoma cells. At the first glance, a multitude of pathways were activated as mitochondria, caspases, p53, XIAP, and STAT3.…”

“…In other circumstances, however, indirubin derivatives have been discussed as even antioxidative. Thus, ROS levels induced by high glucose in rat cardiomyocytes or by LPS in brain microglia cells were diminished by indirubin‐3′‐oxime …”

Double‐stranded RNA‐dependent protein kinase signalling and paradigms of cardiometabolic syndrome

“…Remarkably, oxidative stress and activated PKR are the most prominent risk factors involved in the progression and development of numerous diseases, ranging from the neurodegenerative disorders such as Alzheimer's disease to a broad array of interconnected metabolic diseases including several forms of malignancies . Studies by Bahal et al and Udumula et al have illustrated the role of PKR in metabolic diseases . PKR is activated by multiple stimuli which may be either internal or external such as ER stress, nutrient excess and many other factors .…”

“…Epidemiological data clearly demonstrate that hyperinsulinaemia, insulin resistance, obesity and HTN are interrelated processes . Further, Udumala et al have reported that PKR gets activated in response to stressful environment such as nutrient excess and participates in mediating inflammation, insulin sensitivity and maintenance of glucose homeostasis .…”

“…Most importantly, it has been reported that there exists a multidisciplinary cross‐linking between oxidative stress, inflammatory responses, apoptosis, metabolic diseases and PKR. Accumulating evidence suggests that oxidative stress and PKR are interconnected with each other in the pathogenesis of Met S. They both are also involved in mediating the inflammatory responses and apoptosis in Met S . Oxidative stress is known as a widely accepted key mediator involved in the pathophysiology of numerous neurodegenerative disorders, including several cardiovascular complications and Met S .…”