PT - JOURNAL ARTICLE AU - Horng-Huei Liou AU - Wen Lin AU - Houng-Chi Liou AU - Tur-Fu Huang AU - Wen-Mei Fu TI - Modulation of Protein Kinase A Activation by Fibronectin Matrix Proteins at Developing Neuromuscular Synapses in <em>Xenopus</em> <em>laevis</em> Cell Cultures AID - 10.1124/mol.60.2.348 DP - 2001 Aug 01 TA - Molecular Pharmacology PG - 348--354 VI - 60 IP - 2 4099 - http://molpharm.aspetjournals.org/content/60/2/348.short 4100 - http://molpharm.aspetjournals.org/content/60/2/348.full SO - Mol Pharmacol2001 Aug 01; 60 AB - Extracellular matrix proteins, such as fibronectin, laminin, and collagen, have been implicated in a wide variety of cellular properties, which include cell adhesion, migration, differentiation, and proliferation. In this study, we investigated the modulation of protein kinase A (PKA) activity by matrix proteins at developing motoneurons. The cultures of spinal neurons and myotomal cells were prepared from 1-day-old Xenopus laevis embryos. Spontaneous synaptic currents (SSC) were recorded from innervated myocytes of natural synapses by whole-cell voltage-clamped recordings (V h = −60∼−65 mV). Bath application of agents, which directly or indirectly activate PKA, such as forskolin (20 μM), dibutyryl cAMP (DBcAMP) (1 mM), isoproterenol (10 μM), or albuterol (10 μM), significantly increased SSC frequency in cultures grown on fibronectin (FN)-coated substratum, but not on laminin- or collagen-coated glasses. The evoked synaptic currents increased in response to forskolin in neurons grown on FN substratum. Triflavin, an Arg-Gly-Asp-dependent disintegrin, inhibited potentiating action of isoproterenol in neurons grown on FN substratum, suggesting that integrin is involved in the potentiation of the PKA pathway in the regulation of acetylcholine (ACh) release. There is collaboration of neurotrophic factors and the FN matrix in regulating synaptic transmission in response to DBcAMP. Chronic treatment with neurotrophic factors, such as ciliary neurotrophic factor (150 ng/ml), glial cell line-derived neurotrophic factor (30 ng/ml), or neurotrophin-3 (50 ng/ml), enhanced the SSC-increasing action of DBcAMP in neurons grown on FN-coated glasses. These results suggest that the FN matrix potentiates synaptic transmission in response to PKA activation. Neurotrophic factors may collaborate with FN to regulate spontaneous ACh secretion at developing motoneurons, which may play an important role in the maturation of embryonic neuromuscular synapses.