BMS-345541

The MEK-ERK1/2 and PKC pathways play critical roles in regulating functional changes in tissues, but their interplay remains poorly understood. The vasculature provides an ideal model to study these pathways, particularly under conditions of flow cessation, which is highly relevant to ischemia and other cardiovascular diseases. This study examined the independent roles, additive effects, and time-dependent dynamics of MEK and PKC pathway inhibition in functional receptor upregulation.

Rat basilar arteries were cultured for 48 h with selective inhibitors targeting MEK (Trametinib), PKC (RO-317549) and their downstream ERK (Ulixertinib) and NF-kB (BMS 345541). Functional changes in ET_B receptor responses were assessed via wire myography following stimulation with Sarafotoxin 6c (S6c). Western blot analysis quantified ERK phosphorylation, and the effects of inhibitor timing and combination treatments were evaluated.

MEK inhibition reduced ERK phosphorylation and ET_B receptor-mediated contractility, whereas PKC inhibition had no effect on ERK phosphorylation but significantly reduced ET_B receptor function. Combining MEK and PKC inhibitors produced an additive effect, resulting in greater suppression of functional changes compared to single treatments. At 6 h following flow cessation, PKC inhibition effectively suppressed ET_B receptor function, while MEK inhibition had minimal effects when introduced at this delayed time point.

The MEK and PKC pathways independently drive functional changes in vascular tissue, particularly following flow cessation. MEK inhibition is effective early, while PKC inhibition remains effective when applied later. The additive effects observed with combined MEK and PKC inhibition indicate parallel and functionally independent pathway activation during ET_B receptor upregulation.

Age-related diseases are often linked to chronic inflammation. Senescent cells secrete inflammatory cytokines, chemokines and matrix metalloproteinases, collectively referred to as the senescence-associated secretory phenotype (SASP). The current study discovered that aging leads to the accumulation of senescent tendon stem/progenitor cells (TSPCs) in tendon tissue, resulting in the development of a SASP. Conditioned medium from aged TSPCs induced cellular inflammation in young TSPCs. In addition, we found that Canopy homolog 2 (CNPY2) expression is reduced during tendon aging. CNPY2 deficiency causes TSPCs senescence and SASP. Our findings showed that the NF-κB signaling pathway is activated in CNPY2 knockdown TSPCs, pharmacological inhibition of NF-κB signaling pathway with BMS-345541 attenuated SASP of senescent TSPCs, which indicated that CNPY2 regulates TSPCs SASP might through NF-κB signaling pathway. Our findings suggested that CNPY2 plays an important role in TSPCs senescence and SASP, CNPY2 could be a promising target for age-related tendon disorders.