Biomechanical and biochemical regulation of cathepsin K expression in endothelial cells converge at AP-1 and NF-κB

Abstract

Cathepsins K and V are powerful elastases elevated in endothelial cells by tumor necrosis factor-α (TNFα) stimulation and disturbed blood flow both of which contribute to inflammation-mediated arterial remodeling. However, mechanisms behind endothelial cell integration of biochemical and biomechanical cues to regulate cathepsin production are not known. To distinguish these mechanisms, human aortic endothelial cells (HAECs) were stimulated with TNFα and exposed to pro-remodeling or vasoprotective shear stress profiles. TNFα upregulated cathepsin K via JNK/c-jun activation, but vasoprotective shear stress inhibited TNFα-stimulated cathepsin K expression. JNK/c-jun were still phosphorylated, but cathepsin K mRNA levels were significantly reduced to almost null indicating separate biomechanical regulation of cathepsin K by shear stress separate from biochemical stimulation. Treatment with Bay 11-7082, an inhibitor of IκBα phosphorylation, was sufficient to block induction of cathepsin K by both pro-remodeling shear stress and TNFα, implicating NF-κB as the biomechanical regulator, and its protein levels were reduced in HAECs by vasoprotective shear stress. In conclusion, NF-κB and AP-1 activation were necessary to activate cathepsin K expression in endothelial cells, highlighting integration of biochemical and biomechanical stimuli to control cathepsins K and V, powerful elastases implicated for arterial remodeling due to chronic inflammation and disturbed blood flow.

Sca‐1+ cardiac fibroblasts promote development of heart failure

“…The induction of GM‐CSF production in T cells involves the activation of both NF‐κB and NFAT2 . The activation of NF‐κB pathway was also reported in TNF‐α‐ and IL‐17A‐induced activation of synovial fibroblasts and endothelial cells . In our study, we revealed that the same synergistic activation of NF‐κB and NFAT2 promoted IL‐17A‐induced GM‐CSF production in Sca‐1 + cardiac fibroblasts.…”

Endothelial Cell Biomechanical Responses are Dependent on Both Fluid Shear Stress and Tensile Strain

“…This is different from literature that shear stress can cause marked changes in NF-jB activation. 28,38,57 This could be due to the relatively short duration of mechanical stimulation in the present study (1 h vs. 8, 12 or 24 h in other studies). In our future studies, we will need to increase the duration of mechanical stimulation to address this limitation.…”

The many roles of cathepsins in restenosis

“…Shear stress constitutes a tangential mechanical force that fluctuates at regular intervals in response to the heart's pumping action. Variations in the amplitude and frequency of shear stress within arteries are linked to a wide variety of processes in cardiovascular wellness and disease [ 28 , 29 ]. The expression of Cats is inhibited and the vascular morphology is preserved when the shear force is stable [ 30 ].…”

“…Philip and colleagues observed that the disturbance of blood flow and the presence of tumor necrosis factor alpha (TNFα) led to an increase in the expression of CaK and V in endothelial cells after stent implantation. Conversely, the application of vascular protective shear stress appeared to mitigate the activation of the JNK/c-jun signaling pathway, which in turn limited the activation of CatK by inhibiting the NF-κb pathway [ 28 ]. In an experiment with diabetic rats, it was discovered that laminar flow decreased the activity of CatL produced by endothelial cells, decreased the conversion of latent heparinase into active heparinase, and affected lipoprotein lipase (LPL), thereby influencing myocardial cell metabolism [ 29 ].…”

“…The detection of tumor necrosis factor alpha (TNFa) in the bloodstream plays a significant role in the activation of Cat. Specifically, TNFa stimulates vascular endothelial cells to produce CatK and CatV, which have been associated with arterial remodeling as a result of prolonged inflammation [ 33 ]. In an in vitro study, human aortic epithelial cells at confluence were subjected to stimulation using TNFα or THP-1 macrophage cocultures.…”