NF-κB/p65 Competes With Peroxisome Proliferator-Activated Receptor Gamma for Transient Receptor Potential Channel 6 in Hypoxia-Induced Human Pulmonary Arterial Smooth Muscle Cells

Podocyte-Specific Expression of the Stress Response Protein REDD1 Is Necessary for Diabetes-Induced Podocytopenia

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease, and effective treatment modalities that fully address its molecular etiology are lacking. Prior studies support that the stress response protein REDD1 (regulated in development and DNA damage 1) contributes to the development of diabetes complications. This study investigated a potential role for REDD1 expression in podocytes in diabetes-induced podocyte loss and compromised glomerular filtration. Podocyte-specific REDD1 deletion protected against renal injury, as evidenced by reduced albuminuria, glomerular hypertrophy, and mesangial matrix deposition in streptozotocin (STZ)-induced diabetic mice. Podocyte-specific REDD1 expression was required for diabetes-induced reduction in slit diaphragm (SD) proteins podocin and nephrin. Notably, podocyte-specific REDD1 deletion protected against podocytopenia and preserved glomerular basement membrane and foot process architecture in diabetic mice. In the kidneys of diabetic mice and in human podocyte cultures exposed to hyperglycemic conditions, REDD1 was necessary for increased expression of the transient receptor potential canonical 6 (TRPC6) channel. More specifically, REDD1 promoted nuclear factor-κB-dependent transcription of TRPC6, intracellular calcium entry, and cytoskeletal remodeling under hyperglycemic conditions. Overall, the findings provide new insight into the role of podocyte-specific REDD1 expression in renal pathology and support the possibility that therapeutics targeting REDD1 in podocytes could be beneficial for DN.

ARTICLE HIGHLIGHTS

Diabetes-induced albuminuria and reduced glomerular slit diaphragm proteins were associated with increased kidney REDD1 protein abundance. Podocyte-specific deletion of REDD1 attenuated diabetes-induced slit diaphragm protein reduction and podocyte loss. REDD1 was required for nuclear factor-κB-dependent TRPC6 expression and increased cytoplasmic calcium levels in podocytes. Podocyte-specific expression of REDD1 was necessary for altered glomerular architecture and albuminuria in diabetic mice.

NF-κB in the Radiation Response of A549 Non-Small Cell Lung Cancer Cells to X-rays and Carbon Ions under Hypoxia

Cellular hypoxia, detectable in up to 80% of non-small cell lung carcinoma (NSCLC) tumors, is a known cause of radioresistance. High linear energy transfer (LET) particle radiation might be effective in the treatment of hypoxic solid tumors, including NSCLC. Cellular hypoxia can activate nuclear factor κB (NF-κB), which can modulate radioresistance by influencing cancer cell survival. The effect of high-LET radiation on NF-κB activation in hypoxic NSCLC cells is unclear. Therefore, we compared the effect of low (X-rays)- and high (12C)-LET radiation on NF-κB responsive genes' upregulation, as well as its target cytokines' synthesis in normoxic and hypoxic A549 NSCLC cells. The cells were incubated under normoxia (20% O2) or hypoxia (1% O2) for 48 h, followed by irradiation with 8 Gy X-rays or 12C ions, maintaining the oxygen conditions until fixation or lysis. Regulation of NF-κB responsive genes was evaluated by mRNA sequencing. Secretion of NF-κB target cytokines, IL-6 and IL-8, was quantified by ELISA. A greater fold change increase in expression of NF-κB target genes in A549 cells following exposure to 12C ions compared to X-rays was observed, regardless of oxygenation status. These genes regulate cell migration, cell cycle, and cell survival. A greater number of NF-κB target genes was activated under hypoxia, regardless of irradiation status. These genes regulate cell migration, survival, proliferation, and inflammation. X-ray exposure under hypoxia additionally upregulated NF-κB target genes modulating immunosurveillance and epithelial-mesenchymal transition (EMT). Increased IL-6 and IL-8 secretion under hypoxia confirmed NF-κB-mediated expression of pro-inflammatory genes. Therefore, radiotherapy, particularly with X-rays, may increase tumor invasiveness in surviving hypoxic A549 cells.

Recent Advances in Understanding the Mechanistic Role of Transient Receptor Potential Ion Channels in Patients With Hypertension

The transient receptor potential (TRP) channel superfamily is a group of nonselective cation channels that function as cellular sensors for a wide range of physical, chemical, and environmental stimuli. According to sequence homology, TRP channels are categorized into 6 subfamilies: TRP canonical, TRP vanilloid, TRP melastatin, TRP ankyrin, TRP mucolipin, and TRP polycystin. They are widely expressed in different cell types and tissues and have essential roles in various physiological and pathological processes by regulating the concentration of ions (Ca2+, Mg2+, Na+, and K+) and influencing intracellular signalling pathways. Human data and experimental models indicate the importance of TRP channels in vascular homeostasis and hypertension. Furthermore, TRP channels have emerged as key players in oxidative stress and inflammation, important in the pathophysiology of cardiovascular diseases, including hypertension. In this review, we present an overview of the TRP channels with a focus on their role in hypertension. In particular, we highlight mechanisms activated by TRP channels in vascular smooth muscle and endothelial cells and discuss their contribution to processes underlying vascular dysfunction in hypertension.

Potential of the TRPM7 channel as a novel therapeutic target for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is an intractable vascular disease characterized by a progressive increase in pulmonary vascular resistance caused by pulmonary vascular remodeling, which ultimately leads to right-sided heart failure. PAH remains incurable, despite the development of PAH-targeted therapeutics centered on pulmonary artery relaxants. It is necessary to identify the target molecules that contribute to pulmonary artery remodeling. Transient receptor potential (TRP) channels have been suggested to modulate pulmonary artery remodeling. Our study focused on the transient receptor potential ion channel subfamily M, member 7, or the TRPM7 channel, which modulates endothelial-to-mesenchymal transition and smooth muscle proliferation in the pulmonary artery. In this review, we summarize the role and expression profile of TRPM7 channels in PAH progression and discuss TRPM7 channels as possible therapeutic targets. In addition, we discuss the therapeutic effect of a Chinese herbal medicine, Ophiocordyceps sinensis (OCS), on PAH progression, which partly involves TRPM7 inhibition.