tretinoin and angiogenin

Mutations in human angiogenin (hANG), an angiogenic member of the RNase A superfamily, have been recently reported in patients with amyotrophic lateral sclerosis (ALS), a progressive late-onset neurodegenerative disorder. However, very little is known about the expression and subcellular distribution of ANG in the nervous system or its role in differentiation. Here we report that mouse angiogenin-1 (mAng-1) is strongly expressed in the developing nervous system during mouse embryogenesis and neuroectodermal differentiation of pluripotent P19 embryonal carcinoma cells. mAng1 is strongly expressed in motor neurons (MNs) in the spinal cord and dorsal root ganglia as well as in post-mitotic MNs derived from P19 cells. We also show for the first time that ANG expression is in the growth cones and neurites. NCI 65828, an inhibitor of the ribonucleolytic activity of hANG, affected pathfinding by P19-derived neurons but not neuronal differentiation. Our findings clearly show that ANG plays an important role in neurite pathfinding and this has implications for ALS.

Topics: Amyotrophic Lateral Sclerosis; Animals; Carcinoma, Embryonal; Cell Differentiation; Embryo, Mammalian; Female; Fluorescent Antibody Technique; Male; Mice; Mice, Inbred C57BL; Naphthalenesulfonates; Neurites; Ribonuclease, Pancreatic; Tretinoin; Tumor Cells, Cultured

Several ribonucleases serve as cytotoxic agents in host defense and in physiological cell death pathways. Although certain members of the pancreatic ribonuclease A superfamily can be toxic when applied to the outside of cells, they become thousands of times more toxic when artificially introduced into the cytosol, indicating that internalization is the rate-limiting step for cytotoxicity. We have used three agents that disrupt the Golgi apparatus by distinct mechanisms, retinoic acid, brefeldin A, and monensin, to probe the intracellular pathways ribonucleases take to reach the cytosol. Retinoic acid and monensin potentiate the cytotoxicity of bovine seminal RNase, Onconase, angiogenin, and human ribonuclease A 100 times or more. Retinoic acid-mediated potentiation of ribonucleases is completely blocked by brefeldin A. Ribonucleases appear to route more efficiently into the cytosol through the Golgi apparatus disrupted by monensin or retinoic acid. Intracellular RNA degradation by BS-RNase increased more than 100 times in the presence of retinoic acid confirming that the RNase reaches the cytosol and indicating that degradation of RNA is the intracellular lesion causing toxicity. As retinoic acid alone and Onconase are in clinical trials for cancer therapy, combinations of RNases and retinoic acid in vivo may offer new clinical utility.

Topics: Amino Acid Sequence; Animals; Antineoplastic Agents; Base Sequence; Brefeldin A; Cattle; Cell Survival; Cyclopentanes; Egg Proteins; Golgi Apparatus; Humans; Molecular Sequence Data; Monensin; Proteins; Rats; Ribonuclease, Pancreatic; Ribonucleases; RNA; Tretinoin; Tumor Cells, Cultured