Pyruvate dehydrogenase kinase supports macrophage NLRP3 inflammasome activation during acute inflammation.

Activating the macrophage NLRP3 inflammasome can promote excessive inflammation with severe cell and tissue damage and organ dysfunction. Here, we show that pharmacological or genetic inhibition of pyruvate dehydrogenase kinase (PDHK) significantly attenuates NLRP3 inflammasome activation in murine and human macrophages and septic mice by lowering caspase-1 cleavage and interleukin-1ß (IL-1ß) secretion. Inhibiting PDHK reverses NLRP3 inflammasome-induced metabolic reprogramming, enhances autophagy, promotes mitochondrial fusion over fission, preserves crista ultrastructure, and attenuates mitochondrial reactive oxygen species (ROS) production. The suppressive effect of PDHK inhibition on the NLRP3 inflammasome is independent of its canonical role as a pyruvate dehydrogenase regulator. Our study suggests a non-canonical role of mitochondrial PDHK in promoting mitochondrial stress and supporting NLRP3 inflammasome activation during acute inflammation.

C12, a combretastatin-A4 analog, exerts anticancer activity by targeting microtubules.

Combretastatin A4 and its analogs are undergoing various clinical trials for the treatment of different cancers. This study illustrated the molecular mechanism and antitumor activity of C12, (5-Quinolin-3-yl and 4-(3,4,5-trimethoxyphenyl) substituted imidazol-2-amine), a synthetic analog of CA-4. C12 reduced the tumor volume of MCF-7 xenograft in NOD-SCID mice without affecting the bodyweight of the mice. Further, C12 inhibited the proliferation of several types of cancer cells more efficiently than their noncancerous counterparts. Using GFP-EB1 imaging, the effects of C12 on the interphase microtubule dynamics were determined in live HeLa cells. C12 (10 nM, half-maximal proliferation inhibitory concentration) reduced the growth rate of microtubules by 52% and increased the pause time of microtubules by 68%. In addition, fluorescence recovery after photobleaching analysis demonstrated that 10 nM C12 strongly suppressed spindle microtubule dynamics in HeLa cells. C12 treatment reduced the interpolar distance between the two spindle poles, increased the chromosome congression index, inhibited chromosome movement, and increased the level of mitotic checkpoint complex proteins BubR1 and Mad2. The evidence presented here indicated that C12 could induce different modes of cell death, depending on the extent of microtubule depolymerization. Since C12 targets both the mitotic and non-mitotic cells and showed a stronger activity against cancerous cells than non-cancerous cells, it may have an advantage in cancer chemotherapy. The results significantly enhance our understanding of the antitumor mechanism of the microtubule-depolymerizing agents.

Synthesis, characterisation and biological activities of [(p-cym)RuX(pz4lut)]n+ and [{(p-cym)RuX}2(µ-pz4lut)]n+ (X = Cl, H2O and pz4lut = α,α,α',α'-tetra(pyrazol-1-yl)-2,6-lutidine).

Mononuclear [(p-cym)RuCl(pz4lut)]Cl (1) and dinuclear [{(p-cym)RuCl}2(µ-pz4lut)]Cl2 (2) complexes (p-cym = 1-isopropyl-4-methylbenzene) comprising of bis(pyrazol-1-yl)methane based heteroscorpionate ligand α,α,α',α'-tetra(pyrazol-1-yl)-2,6-lutidine (pz4lut) have been synthesised from pz4lut ligand and dimeric precursor complex [(p-cym)RuCl(µ-Cl)]2 in methanol. The aqua derivatives [(p-cym)Ru(H2O)(pz4lut)](ClO4)2 (3) and [{(p-cym)Ru(H2O)}2(µ-pz4lut)](ClO4)4 (4) are obtained from 1 and 2, respectively, via Cl/H2O exchange process in presence of appropriate equivalents of AgClO4 in methanol­water mixture. The molecular structures of dinuclear complexes, 2 and 4 are authenticated by their single crystal X-ray structures. Cyclic voltammetry reveals negligible electronic communication between the metal centres in the ligand bridged complex 2. All four complexes have been tested for their anticancer activities in human breast (MCF7), lung (A549) and colon (HCT116) cancer cell lines. The complexes show dose dependent suppression of cell viability with moderately good IC50 values ranging from 3.5­92 µM. Experimental results have revealed that the aqua derivatives, 3 and 4 exhibit better cytotoxic effect against all those cell lines as compared to the precursor chlorido complexes, 1 and 2. Results also demonstrate that the complexes are more potent against HCT116 cells as compared to other cell lines.