Rho-kinase regulation of TNF-α-induced nuclear translocation of NF-κB RelA/p65 and M-CSF expression via p38 MAPK in mesangial cells

Abstract

The small GTPase Rho and its downstream effector, Rho-associated coiled-coil containing protein kinase (Rho-kinase), regulate a number of cellular processes, including organization of the actin cytoskeleton, cell adhesion, and migration. While pharmacological inhibitors of Rhokinase signaling are known to block renal inflammation, the molecular basis for this effect is unclear. Here, we provide evidence that proinflammatory TNF-␣ promotes mesangial expression of macrophage colony-stimulating factor (M-CSF), a key regulator for the growth and differentiation of mononuclear phagocytes, in a Rhokinase-dependent manner. Consistent with this observation, TNF-␣-mediated renal expression of M-CSF in insulin-resistant db/db mice was downregulated by Rho-kinase inhibition. Small interfering RNAfacilitated knockdown of Rho-kinase isoforms ROCK1 and ROCK2 indicated that both isoforms make comparable contributions to regulation of M-CSF expression in mesangial cells. From a mechanistic standpoint, Western blotting and EMSA showed that Rho-kinase and its downstream target p38 MAPK regulate nuclear translocation of NF-B RelA/p65 and subsequent DNA binding activity, with no significant effects on IB␣ degradation and RelA/p65 phosphorylation. Moreover, we showed that Rho-kinase-mediated cytoskeletal organization is required for the nuclear uptake of RelA/p65. Collectively, these findings identify Rho-kinase as a critical regulator of chemokine expression and macrophage proliferation.

Dyslipidemia in diabetic nephropathy

“…This was also confirmed by a chemotaxis assay demonstrating that monocytic migration toward mesangial cells was suppressed by a Rho-kinase inhibitor [54]. The expression of macrophage colony-stimulating factor (M-CSF), another important chemotactic cytokine, was also induced by TNF-α via activation of Rho-kinase in cultured mesangial cells [55]. Small interfering RNA-mediated knockdown of ROCK1 and ROCK2, two isoforms of Rho-kinase, indicated that both isoforms have a comparable contribution to the M-CSF expression in mesangial cells.…”

“…We found that TNF-α enhances nuclear translocation of RelA/p65 in cultured mesangial cells. Interestingly, Rhokinase inhibitor suppressed nuclear translocation of RelA/p65 and accordingly reduced the promoter activity of the NF-κB binding site [55]. This study provided new insight on the role of Rho-kinase, demonstrating that Rho-kinase may regulate intracellular translocation of transcriptional factors, likely through re-organization of actin stress fibers.…”

Andrographolide Activates Keap1/Nrf2/ARE/HO-1 Pathway in HT22 Cells and Suppresses Microglial Activation by Aβ42through Nrf2-Related Inflammatory Response

“…As shown in Figure 5(a), pNF- κ B (Ser536) accumulated in the nucleus when BV-2 cells were transfected with 2.0  μ g of A β 42 , and the nuclear accumulation of pNF- κ B was dramatically decreased after andrographolide treatment by concentrations. Mainly, pNF- κ B RelA/p65-p50 heterodimer is transported to nucleus after releasing from I κ B α and phosphorylation at Ser536 [27]. Our results showed that pNF- κ B accumulation in nucleus was suppressed by andrographolide treatment; however their specific mechanism is not yet clarified.…”

The Spleen Tyrosine Kinase (Syk) Regulates Alzheimer Amyloid-β Production and Tau Hyperphosphorylation

“…The signaling pathways responsible for the activation of NFB by TNF␣ or PMA have been described in the literature, and we explored whether elements of these pathways were impacted by (Ϫ)-nilvadipine. For instance, the small GTPase Rho and its downstream effector Rho-associated coiled-coil containing protein kinase (ROCK) have been shown to contribute to TNF␣ induction of NFB activation (45). We found that nilvadipine was ineffective at inhibiting ROCK activity in a cell-free assay excluding ROCK as possible target of nilvadipine (data not shown).…”