AKIP1, a Cardiac Hypertrophy Induced Protein that Stimulates Cardiomyocyte Growth via the Akt Pathway

Cardiac adaptation to unremitting physiological stress typically involves hypertrophic growth of cardiomyocytes, a compensatory response that often fails and causes heart disease. Gene array analysis identified AKIP1 (A Kinase Interacting Protein 1) as a hypertrophic gene and we therefore hypothesized a potential role in the hypertrophic response. We show for the first time that both AKIP1 mRNA and protein levels increased in hypertrophic cardiomyocytes under conditions of sustained cardiac stress, including pressure overload and after myocardial infarction and in vitro in phenylephrine (PE) stimulated neonatal rat ventricular cardiomyocytes (NRVCs). AKIP1 overexpression in NRVCs markedly stimulated hypertrophic growth responses, including significantly increased cell size, augmented cytoskeletal organization and protein synthesis. Although, AKIP1 was not essential for PE induced hypertrophy in NRVCs, it did potentiate neurohormonal induced protein synthesis. AKIP1 did, however, not induce expression of pathological marker genes like ANP and β-MHC. ERK and Akt kinase signaling pathways have been linked to hypertrophy and AKIP1 specifically induced phosphorylation of Akt. This phosphorylation of Akt was essential for activation of ribosomal rpS6 and translation elongation factor eEF2 and this readily explains the increased protein synthesis. Akt inhibition fully blocked AKIP1 induced hypertrophy, showing that this pathway is critically involved. In conclusion, our results show that AKIP1 is induced in hypertrophic hearts and can stimulate adaptive cardiomyocyte growth, which involves Akt signaling.     

Selective and Brain‐Permeable Polo‐like Kinase‐2 (Plk‐2) Inhibitors That Reduce α‐Synuclein Phosphorylation in Rat Brain

Polo‐like kinase‐2 (Plk‐2) has been implicated as the dominant kinase involved in the phosphorylation of α‐synuclein in Lewy bodies, which are one of the hallmarks of Parkinson’s disease neuropathology. Potent, selective, brain‐penetrant inhibitors of Plk‐2 were obtained from a structure‐guided drug discovery approach driven by the first reported Plk‐2–inhibitor complexes. The best of these compounds showed excellent isoform and kinome‐wide selectivity, with physicochemical properties sufficient to interrogate the role of Plk‐2 inhibition in vivo. One such compound significantly decreased phosphorylation of α‐synuclein in rat brain upon oral administration and represents a useful probe for future studies of this therapeutic avenue toward the potential treatment of Parkinson’s disease.     

Electrochemical investigations of sarcoma-related protein kinase inhibition

An electrochemical biosensor was developed for the determination of sarcoma (Src)-related protein kinase-catalyzed phosphorylation reactions in the presence of adenosine 5′-γ-ferrocenoyl triphosphate (Fc-ATP). The sensing platform is based on a highly specific amino acid sequence Glu-Gly-Ile-Tyr-Asp-Val-Pro (EGIYDVP), to which a Fc-PO₂ moiety can be transferred from Fc-ATP by the action of the Src kinase. The enzyme kinetics and kinase inhibition were investigated by square wave voltammetry (SWV). The kinetic parameters K_m and V_max were determined for Src protein kinase with respect to Fc-ATP co-substrate and were found to be 200 μM and 115 μA cm⁻² min, for phosphorylation of the EGIYDVP peptide substrate. Furthermore, the Src-catalyzed phosphorylation of Tyr was investigated in the presence of the small molecule inhibitors PP1, PP2, SU6656, and roscovitine. PP3 does not inhibit Src activity and was used as a control. The percent inhibition at half concentration, IC₅₀, values were determined for all inhibitors under the study and were estimated to be in the 5–30 nM range. The electrochemical study suggests that the increase in inhibition efficiency was in the order PP3 < SU6656 < roscovitine < PP2 < PP1.     

Lemur Tyrosine Kinases and Prostate Cancer: A Literature Review

The members of the Lemur Tyrosine Kinases (LMTK1-3) subfamily constitute a group of three membrane-anchored kinases. They are known to influence a wide variety of key cellular events, often affecting cell proliferation and apoptosis. They have been discovered to be involved in cancer, in that they impact various signalling pathways that influence cell proliferation, migration, and invasiveness. Notably, in the context of genome-wide association studies, one member of the LMTK family has been identified as a candidate gene which could contribute to the development of prostate cancer. In this review, of published literature, we present evidence on the role of LMTKs in human prostate cancer and model systems, focusing on the complex network of interacting partners involved in signalling cascades that are frequently activated in prostate cancer malignancy. We speculate that the modulators of LMTK enzyme expression and activity would be of high clinical relevance for the design of innovative prostate cancer treatment.     

Alteration of energy metabolism in Enterobacter aerogenes by external addition of pyrophosphates and overexpression of polyphosphate kinase for enhanced hydrogen production

BACKGROUND: Bacterial hydrogen evolution releases excess electrons or energy formed during the metabolic oxidations. Until now, few studies have investigated the global regulation of cellular energy flows, pertaining to bacterial hydrogen production for the improvement of hydrogen production. In this study, the cellular energy metabolism of Enterobacter aerogenes was regulated by the addition of pyrophosphate (PPi) and the overexpression of polyphosphate kinase (PPK), to improve hydrogen production. RESULTS: By overexpressing PPK at 10 mmol L^?1 PPi, total hydrogen yields were increased by 32.7%. Metabolic flux analysis demonstrated that overexpression of PPK in E. aerogenes resulted in a higher cellular ATP level and a higher NADH consumption rate, which changed the cellular redox state and allowed more electrons to flow into the hydrogen production pathway. CONCLUSION: Alteration of the energy metabolism in E. aerogenes can affect hydrogen production. This implies that if one could accurately control the energy flow or the electron flow in the cells, hydrogen productivity would be further greatly improved. Copyright © 2012 Society of Chemical Industry     

Aurora-B激酶特异性抑制剂AZD1152-HQPA对人骨肉瘤细胞株U2-OS细胞的抑制作用

目的探讨激光（Aurora）-B激酶特异性抑制剂AZD1152-HQPA对人骨肉瘤细胞株U2-OS细胞的抑制作用。方法用不同浓度的AZD1152-HQPA（0、10、50、100、500 nmol.L-1）体外作用于人骨肉瘤细胞株U2-OS24、48、72 h,采用噻唑蓝（MTT）检测AZD1152-HQPA对人骨肉瘤细胞株U2-OS细胞的抑制作用;采用Western Blotting检测AZD1152-HQPA作用于人骨肉瘤细胞株U2-OS细胞前后Aurora-B激酶的表达情况。结果 AZD1152-HQPA对人骨肉瘤细胞株U2-OS细胞生长抑制作用明显,且抑制呈时间-浓度依赖性。50 nmol.L-1AZD1152-HQPA作用24、48、72 h,人骨肉瘤细胞株U2-OS细胞中Aurora-B激酶的表达随作用时间的延长而降低。结论 AZD1152-HQ-PA能抑制U2-OS细胞生长,并且抑制作用呈时间-浓度依赖性。