title: The C1 domain-targeted isophthalate derivative HMI-1b11 promotes neurite outgrowth and GAP-43 expression through PKCα activation in SH-SY5Y cells.
abstract: Protein kinase C (PKC) is a family of serine/threonine phosphotransferases ubiquitously expressed and involved in multiple cellular functions, such as proliferation, apoptosis and differentiation. The C1 domain of PKC represents an attractive drug target, especially for developing PKC activators. Dialkyl 5-(hydroxymethyl)isophthalates are a novel group of synthetic C1 domain ligands that exhibit antiproliferative effect in HeLa cervical carcinoma cells. Here we selected two isophthalates, HMI-1a3 and HMI-1b11, and characterized their effects in the human neuroblastoma cell line SH-SY5Y. Both of the active isophthalates exhibited significant antiproliferative and differentiation-inducing effects. Since HMI-1b11 did not impair cell survival even at the highest concentration tested (20μM), and supported neurite growth and differentiation of SH-SY5Y cells, we focused on studying its downstream signaling cascades and effects on gene expression. Consistently, genome-wide gene expression microarray and gene set enrichment analysis indicated that HMI-1b11 (10μM) induced changes in genes mainly related to cell differentiation. In particular, further studies revealed that HMI-1b11 exposure induced up-regulation of GAP-43, a marker for neurite sprouting and neuronal differentiation. These effects were induced by a 7-min HMI-1b11 treatment and specifically depended on PKCα activation, since pretreatment with the selective inhibitor Gö6976 abolished the up-regulation of GAP-43 protein observed at 12h. In parallel, we found that a 7-min exposure to HMI-1b11 induced PKCα accumulation to the cytoskeleton, an effect that was again prevented by pretreatment with Gö6976. Despite similar binding affinities to PKC, the isophthalates had different effects on PKC-dependent ERK1/2 signaling: HMI-1a3-induced ERK1/2 phosphorylation was transient, while HMI-1b11 induced a rapid but prolonged ERK1/2 phosphorylation. Overall our data are in accordance with previous studies showing that activation of the PKCα and ERK1/2 pathways participate in regulating neuronal differentiation. Furthermore, since PKC has been classified as one of the cognitive kinases, and activation of PKC is considered a potential therapeutic strategy for the treatment of cognitive disorders, our findings suggest that HMI-1b11 represents a promising lead compound in research aimed to prevent or counteract memory impairment.
authors: Division of Pharmacology and Toxicology, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland. virpi.talman@helsinki.fi
authors: Virpi
authors: V
authors: Talman
authors: Marialaura
authors: M
authors: Amadio
authors: Cecilia
authors: C
authors: Osera
authors: Salla
authors: S
authors: Sorvari
authors: Gustav
authors: G
authors: Boije Af Gennäs
authors: Jari
authors: J
authors: Yli-Kauhaluoma
authors: Daniela
authors: D
authors: Rossi
authors: Stefano
authors: S
authors: Govoni
authors: Simona
authors: S
authors: Collina
authors: Elina
authors: E
authors: Ekokoski
authors: Raimo K
authors: RK
authors: Tuominen
authors: Alessia
authors: A
authors: Pascale
mesh_terms: D002454:Cell Differentiation; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019922:GAP-43 Protein / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D016501:Neurites / Q000187:drug effects* / Q000502:physiology; D009447:Neuroblastoma / Q000378:metabolism; D010795:Phthalic Acids / Q000737:chemistry / Q000494:pharmacology*; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017434:Protein Structure, Tertiary
chemical_list: D019922:GAP-43 Protein; D010795:Phthalic Acids; D047428:Protein Kinase Inhibitors; C059768:isophthalate; C496628:PRKCA protein, human; D051571:Protein Kinase C-alpha