KN-92 phosphate

KN-92 is an inactive derivative of KN-93. It is intended to be used as a control compound in studies designed to elucidate the antagonist activities of KN-93. KN-93 is a selective inhibitor of Ca2+/calmodulin-dependent kinase II (CaMKII), competitively blocking CaM binding to the kinase (Ki = 370 nM). KN-93 inhibits histamine-induced aminopyrine uptake in parietal cells (IC50 = 300 nM). KN-93 has been used to implicate roles for CaMKII in Ca2+-induced Ca2+ release in cardiac myocytes, constitutive phosphorylation of 5-lipoxygenase in 3T3 cells, and Ca2+-dependent activation of HIF-1α in colon cancer cell.

Polyester fibers can be rendered calcium phosphate-binding by surface functionalization with bisphosphonate groups.[Pubmed:28371150]

J Biomed Mater Res A. 2017 Aug;105(8):2335-2342.

Fibers are often used as structural elements to improve the mechanical properties of materials such as brittle ceramic matrices by facilitating the dissipation of energy. However, this energy dissipation is mainly controlled by the interface between the two components, and a poorly designed fiber-matrix interface strongly reduces the efficacy of fiber reinforcement. Here, we present a versatile approach to control the affinity of biocompatible fibers to calcium-containing matrices to maximize the efficacy of reinforcement of calcium phosphates-based bioceramics by means of polymeric fibers. To this end, polyester fibers of tunable length were produced by electrospinning and aminolysis, followed by covalent attachment of alendronate, a bisphosphonate molecule with strong calcium-binding affinity, to the surface of the fibers. The proposed method allowed for selective control over the amount of alendronate conjugation, thereby improving the affinity of polyester fibers toward calcium phosphate bioceramics. (c) 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2335-2342, 2017.

Fabrication of self-setting beta-tricalcium phosphate granular cement.[Pubmed:28370963]

J Biomed Mater Res B Appl Biomater. 2018 Feb;106(2):800-807.

Bone defect reconstruction would be greatly improved if beta-tricalcium phosphate (beta-TCP) granules had the ability to self-set without sacrificing their osteoconductivity potential. This study aimed to identify a method to permit beta-TCP self-setting whilst maintaining good osteoconductivity. When mixed with acidic calcium phosphate solution, beta-TCP granules were found to readily set, forming a fully interconnected porous structure. On mixing, dicalcium phosphate dihydrate crystals formed on the surface of beta-TCP granules, bridging the granules and resulting in the setting reaction. The setting time of the beta-TCP granular cement (beta-TCP GC) was approximately 1 min and its mechanical strength, in terms of diametral tensile strength, was approximately 0.8 MPa. The beta-TCP GC and beta-TCP granules both showed the same level of osteoconductivity within rat calvaria bone defects. At 2 and 4 weeks post-implantation, new bone formation was comparable between the two beta-TCP based bone substitutes. We conclude that beta-TCP GC has excellent potential for use as a cement in bone defect reconstruction. (c) 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 800-807, 2018.

Highly Time-Resolved Metabolic Reprogramming toward Differential Levels of Phosphate in Chlamydomonas reinhardtii.[Pubmed:28372038]

J Microbiol Biotechnol. 2017 Jun 28;27(6):1150-1156.

Understanding phosphorus metabolism in photosynthetic organisms is important as it is closely associated with enhanced crop productivity and pollution management for natural ecosystems (e.g., algal blooming). Accordingly, we exploited highly time-resolved metabolic responses to different levels of phosphate deprivation in Chlamydomonas reinhardtii, a photosynthetic model organism. We conducted non-targeted primary metabolite profiling using gas-chromatography time-of-flight mass spectrometric analysis. Primarily, we systematically identified main contributors to degree-wise responses corresponding to the levels of phosphate deprivation. Additionally, we systematically characterized the metabolite sets specific to different phosphate conditions and their interactions with culture time. Among them were various types of fatty acids that were most dynamically modulated by the phosphate availability and culture time in addition to phosphorylated compounds.

OsPAP26 Encodes a Major Purple Acid Phosphatase and Regulates Phosphate Remobilization in Rice.[Pubmed:28371895]

Plant Cell Physiol. 2017 May 1;58(5):885-892.

During phosphate (Pi) starvation or leaf senescence, the accumulation of intracellular and extracellular purple acid phosphatases (PAPs) increases in plants in order to scavenge organic phosphorus (P). In this study, we demonstrated that a PAP-encoding gene in rice, OsPAP26, is constitutively expressed in all tissues. While the abundance of OsPAP26 transcript is not affected by Pi supply, it is up-regulated during leaf senescence. Furthermore, Pi deprivation and leaf senescence greatly increased the abundance of OsPAP26 protein. Overexpression or RNA interference (RNAi) of OsPAP26 in transgenic rice significantly increased or reduced APase activities, respectively, in leaves, roots and growth medium. Compared with wild-type (WT) plants, Pi concentrations of OsPAP26-overexpressing plants increased in the non-senescing leaves and decreased in the senescing leaves. The increased remobilization of Pi from the senescing leaves to non-senescing leaves in the OsPAP26-overexpressing plants resulted in better growth performance when plants were grown in Pi-depleted condition. In contrast, OsPAP26-RNAi plants retained more Pi in the senescing leaves, and were more sensitive to Pi starvation stress. OsPAP26 was found to localize to the apoplast of rice cells. Western blot analysis of protein extracts from callus growth medium confirmed that OsPAP26 is a secreted PAP. OsPAP26-overexpressing plants were capable of converting more ATP into inorganic Pi in the growth medium, which further supported the potential role of OsPAP26 in utilizing organic P in the rhizosphere. In summary, we concluded that OsPAP26 performs dual functions in plants: Pi remobilization from senescing to non-senescing leaves; and organic P utilization.

KN-93 (2-[N-(2-hydroxyethyl)]-N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N -methylbenzylamine), a calcium/calmodulin-dependent protein kinase II inhibitor, is a direct extracellular blocker of voltage-gated potassium channels.[Pubmed:16368898]

J Pharmacol Exp Ther. 2006 Apr;317(1):292-9.

The effect of Ca(2+)/calmodulin-dependent protein kinase II (CaMK II) on voltage-gated ion channels is widely studied through the use of specific CaMK II blockers such as 2-[N-(2-hydroxyethyl)]-N-(4methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-m ethylbenzylamine (KN-93). The present study demonstrates that KN-93 is a direct extracellular blocker of a wide range of cloned Kv channels from a number of different subfamilies. In all channels tested, the effect of 1 microM KN-93 was independent of CaMK II because 1 microM2-[N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylam ine, phosphate (KN-92), an inactive analog of KN-93, caused similar inhibition of currents. In addition, dialysis of cells with 10 microM CaMK II inhibitory peptide fragment 281-301 (CIP) had no effect on current kinetics and did not prevent the inhibitory effect of KN-93. The IC(50) for block of the Kv1.5 channel (used as an example to determine the nature of KN-93 block) was 307 +/- 12 nM. KN-93 blocked open channels with little voltage dependence that did not alter the V(1/2) of channel activation. Removal of P/C-type inactivation by mutation of arginine 487 to valine in the outer pore region of Kv1.5 (R487V) greatly reduced KN-93 block, whereas enhancement of inactivation induced by mutation of threonine 462 to cysteine (T462C) increased the potency of KN-93 by 4-fold. This suggested that KN-93 acted through promotion and stabilization of C-type inactivation. Importantly, KN-93 was ineffective as a blocker when applied intracellularly, suggesting that CaMK II-independent effects of KN-93 on Kv channels can be circumvented by intracellular application of KN-93.