Gain of function mutation in K(ATP) channels and resulting upregulation of coupling conductance are partners in crime in the impairment of Ca2+ oscillations in pancreatic ß-cells.

Gain of function mutations in the pore forming Kir6 subunits of the ATP sensitive K+ channels (K(ATP) channels) of pancreatic ß-cells are the major cause of neonatal diabetes in humans. In this study, we show that in insulin secreting mouse ß-cell lines, gain of function mutations in Kir6.1 result in a significant connexin36 (Cx36) overexpression, which form gap junctional connections and mediate electrical coupling between ß-cells within pancreatic islets. Using computational modeling, we show that upregulation in Cx36 might play a functional role in the impairment of glucose stimulated Ca2+ oscillations in a cluster of ß-cells with Kir6.1 gain of function mutations in their K(ATP) channels (GoF-K(ATP) channels). Our results show that without an increase in Cx36 expression, a gain of function mutation in Kir6.1 might not be sufficient to diminish glucose stimulated Ca2+ oscillations in a ß-cell cluster. We also show that a reduced Cx36 expression, which leads to loss of coordination in a wild-type ß-cell cluster, restores coordinated Ca2+ oscillations in a ß-cell cluster with GoF-K(ATP) channels. Our results indicate that in a heterogenous ß-cell cluster with GoF-K(ATP) channels, there is an inverted u-shaped nonmonotonic relation between the cluster activity and Cx36 expression. These results show that in a neonatal diabetic ß-cell model, gain of function mutations in the Kir6.1 cause Cx36 overexpression, which aggravates the impairment of glucose stimulated Ca2+ oscillations.

Synthesis, Biological Activity Evaluation and Molecular Docking of Imidazole Derivatives Possessing Hydrazone Moiety.

In an attempt to identify potential active anticancer agents with low cytotoxic properties and CA inhibitors, a new series of hybrid compounds incorporating imidazole ring and hydrazone moiety as part of their structure were synthesized by aza-Michael addition reaction followed by intramolecular cyclization. The structure of synthesized compounds was elucidated using various spectral techniques. Synthesized compounds were evaluated for their in vitro anticancer (prostate cell lines; PC3) and CA inhibitory (hCA I and hCA II) activity. Among them, some compound displayed remarkable anticancer activity and CA inhibitory activity with Ki values in range of 17.53±7.19-150.50±68.87 nM against cytosolic hCA I isoform associated with epilepsy, and 28.82±14.26-153.27±55.80 nM against dominant cytosolic hCA II isoforms associated with glaucoma. Furthermore, the theoretical parameters of the bioactive molecules were calculated to establish their drug-likeness qualities. The proteins used for the calculations are prostate cancer protein (PDB ID: 3RUK and 6XXP). ADME/T analysis was carried out to examine the drug properties of the studied molecules.

Tip60/Kat5 may be a novel candidate histone acetyltransferase for the regulation of liver iron localization via acetylation.

Hepcidin (HAMP), an iron regulatory hormone synthesized by liver hepatocytes, works together with ferritin (FTH) and ferroportin (FPN) in regulating the storage, transport, and utilization of iron in the cell. Epigenetic mechanisms, especially acetylation, also play an important role in the regulation of iron metabolism. However, a target protein has not been mentioned yet. With this preliminary study, we investigated the effect of histone acetyltransferase TIP60 on the expression of HAMP, FTH, and FPN. In addition, how the depletion of Tip60, which regulates the circadian system, affects the daily expression of Hamp was examined at six Zeitgeber time (ZT) points. For this purpose, liver-specific Tip60 knockout mice (mutant) were produced with tamoxifen-inducible Cre/lox recombination and an iron overload model in mice was generated. While HAMP and FTH expressions decreased, FPN expression increased in the mutant group. Interestingly, there was no change in the iron content. A significant increase was observed in the expressions of HAMP, FTH, and FPN and total liver iron content in the liver tissue of the iron overload group. Since intracellular iron concentration is involved in regulating the circadian clock, temporal expression of Hamp was investigated in control and mutant groups at six ZT points. In the control group, Hamp accumulated in a circadian manner with maximal and minimal levels reaching around ZT16 and ZT8, respectively. In the mutant group, there was a significant reduction in Hamp expression in the light phase ZT0 and ZT4 and in the dark phase ZT16. These data are the first findings demonstrating a possible relationship between Tip60 and iron metabolism.