De novo actin polymerization is required for model Hirano body formation in Dictyostelium.

Hirano bodies are eosinophilic, actin-rich inclusions found in autopsied brains in numerous neurodegenerative diseases. The mechanism of Hirano body formation is unknown. Mass spectrometry analysis was performed to identify proteins from partially purified model Hirano bodies from Dictyostelium This analysis identified proteins primarily belonging to ribosomes, proteasomes, mitochondria and cytoskeleton. Profilin, Arp/2/3 and WASH identified by mass spectrometry were found to colocalise with model Hirano bodies. Due to their roles in actin regulation, we selected these proteins for further investigation. Inhibition of the Arp2/3 complex by CK666 prevented formation of model Hirano bodies. Since Arp2/3 activation occurs via the WASH or WAVE complex, we next investigated how these proteins affect Hirano body formation. Whereas model Hirano bodies could form in WASH-deficient cells, they failed to form in cells lacking HSPC300, a member of the WAVE complex. We identified other proteins required for Hirano body formation that include profilin and VASP, an actin nucleation factor. In the case of VASP, both its G- and F-actin binding domains were required for model Hirano body formation. Collectively, our results indicate that de novo actin polymerization is required to form model Hirano bodies.

Synthesis and evaluation of analogues of 5'-([(Z)-4-amino-2-butenyl]methylamino)-5'-deoxyadenosine as inhibitors of tumor cell growth, trypanosomal growth, and HIV-1 infectivity.

A well-defined series of 5'-([(Z)-4-amino-2-butenyl]methylamino)-5'-deoxyadenosine analogues was designed and synthesized in order to further ascertain the optimal structural requirements for S-adenosylmethionine decarboxylase inhibition and potentially to augment and perhaps separate their antiproliferative and antitrypanosomal activities. Most structural modifications had a deleterious affect on both the antitrypanosomal and antineoplastic activity of 5'-([(Z)-4-amino-2-butenyl]methylamino)-5'-deoxyadenosine. However, di-O-acetylation of the parent compound produced a potential prodrug that caused markedly pronounced inhibition of trypanosomal and neoplastic cell growth and viability. Moreover, the acetylated derivative of 5'-([(Z)-4-amino-2-butenyl]methylamino)-5'-deoxyadenosine did inhibit HIV-1 growth and infectivity, whereas the parent compound did not.

Synthesis and evaluation of a novel synthetic phosphocholine lipid-AZT conjugate that double-targets wild-type and drug resistant variants of HIV.

INK-20, a synthetic phosphocholine lipid-AZT conjugate, was evaluated for antiviral activity against wild-type HIV-1, a matched pair of pre-AZT and post-AZT and multidrug resistant clinical isolates. In addition, it was tested for activity against viruses resistant to nucleoside (AZT, 3TC) and nonnucleoside (nevirapine) reverse transcriptase and protease (saquinavir) inhibitors using the syncytial plaque reduction assay for infectious virus multiplication. The EC50 values were 0.004, and 0.005 microM against wild-type HIV-1 for INK-20 and AZT, respectively. INK-20 showed little or no cytotoxicity when assayed in CEM-SS cells and four other cell types including PBMC. This resulted in a selective index of > 25,000 and > 20,000 for INK-20 and AZT, respectively. When tested against a matched pair of pre-AZT and post-AZT clinical isolates, the EC50 values were 0.01 and 0.03 microM for INK-20 and 0.0005 and 0.33 microM for AZT, respectively. INK-20 had moderate to good activity against two other AZT resistant variants and very good activity against a multi-drug resistant clinical isolate compared to marked resistance of these viruses to AZT alone. INK-20 retained significant activity against viruses resistant to 3TC, nevirapine, and saquinavir. The synthetic phosphocholine lipid-AZT conjugate INK-20 represents a novel class of anti-HIV compounds, which may provide new strategies for the treatment of HIV drug-resistant variants.