ABSTRACT
Identification of novel pro-survival factors in the brain is paramount for developing neuroprotective therapies. The multifunctional S100 family proteins have important roles in many human diseases and are also upregulated by brain injury. However, S100 functions in the nervous system remain unclear. Here we show that the S100A4 protein, mostly studied in cancer, is overexpressed in the damaged human and rodent brain and released from stressed astrocytes. Genetic deletion of S100A4 exacerbates neuronal loss after brain trauma or excitotoxicity, increasing oxidative cell damage and downregulating the neuroprotective protein metallothionein I+II. We identify two neurotrophic motifs in S100A4 and show that these motifs are neuroprotective in animal models of brain trauma. Finally, we find that S100A4 rescues neurons via the Janus kinase/STAT pathway and, partially, the interleukin-10 receptor. Our data introduce S100A4 as a therapeutic target in neurodegeneration, and raise the entire S100 family as a potentially important factor in central nervous system injury.
Subject(s)
Cytoprotection , Neoplasm Metastasis/pathology , Neurons/pathology , S100 Proteins/metabolism , Amino Acid Motifs , Animals , Brain Injuries/drug therapy , Brain Injuries/metabolism , Brain Injuries/pathology , Cell Death/drug effects , Cytoprotection/drug effects , Female , Gene Deletion , HEK293 Cells , Humans , Janus Kinases/metabolism , Kainic Acid , Mice , Mice, Inbred C57BL , Neurons/drug effects , Neurons/metabolism , Neuroprotective Agents/metabolism , Neurotoxins/toxicity , Oxidative Stress/drug effects , Peptides/pharmacology , Peptides/therapeutic use , Rats , Receptors, Interleukin-10/metabolism , S100 Calcium-Binding Protein A4 , S100 Proteins/chemistry , STAT Transcription Factors/metabolism , Seizures/drug therapy , Seizures/pathology , Up-Regulation/drug effectsABSTRACT
Erythropoietin, a member of the type 1 cytokine superfamily, controls proliferation and differentiation of erythroid progenitor cells through binding to and dimerization of the erythropoietin receptor. Both erythropoietin and its receptor are also expressed in the central nervous system, where they are involved in tissue protection. However, the use of erythropoietin as a neuroprotective agent may be hampered by its erythropoietic activity. Therefore, developing non-haematopoietic erythropoietin mimetics is important. Based on the crystal structure of the complex of erythropoietin and its receptor, we designed a peptide, termed Epotris, corresponding to the C α-helix region (amino-acid residues 92-111) of human erythropoietin. The peptide specifically bound to the erythropoietin receptor and promoted neurite outgrowth and survival of primary neurons with the same efficiency as erythropoietin, but with 10(3)-fold lower potency. Knockdown of the erythropoietin receptor or interference with its downstream signalling inhibited the Epotris-induced neuritogenic and pro-survival effect. Similarly to erythropoietin, Epotris penetrated the blood-brain barrier. Moreover, treatment with the peptide attenuated seizures, decreased mortality and reduced neurodegeneration in an in vivo model of kainic acid-induced neurotoxicity. In contrast to erythropoietin, Epotris did not stimulate erythropoiesis upon chronic administration. Thus, Epotris is a novel neuroprotective non-haematopoietic erythropoietin mimetic that may offer new opportunities for the treatment of neurological disorders.
Subject(s)
Erythropoietin/pharmacology , Neuroprotective Agents/pharmacology , Peptide Fragments/pharmacology , Receptors, Erythropoietin/agonists , Animals , Blood-Brain Barrier/drug effects , Blood-Brain Barrier/metabolism , Capillary Permeability/drug effects , Capillary Permeability/physiology , Cells, Cultured , Erythropoiesis/drug effects , Erythropoiesis/physiology , Erythropoietin/chemistry , Erythropoietin/metabolism , Erythropoietin/pharmacokinetics , Female , Gene Knockdown Techniques , Humans , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Neurites/drug effects , Neurites/physiology , Neurodegenerative Diseases/drug therapy , Neurodegenerative Diseases/mortality , Neurons/drug effects , Neurons/physiology , Neuroprotective Agents/chemistry , Neuroprotective Agents/pharmacokinetics , Peptide Fragments/chemistry , Peptide Fragments/pharmacokinetics , Rats , Rats, Wistar , Receptors, Erythropoietin/genetics , Receptors, Erythropoietin/metabolism , Seizures/drug therapy , Seizures/mortalityABSTRACT
Metallothioneins I and II (MTI/II) are metal-binding proteins overexpressed in response to brain injury. Recently, we have designed a peptide, termed EmtinB, which is modeled after the beta-domain of MT-II and mimics the biological effects of MTI/II in vitro. Here, we demonstrate the neuroprotective effect of EmtinB in the in vitro and in vivo models of kainic acid (KA)-induced neurotoxicity. We show that EmtinB passes the blood-brain barrier and is detectable in plasma for up to 24 hr. Treatment with EmtinB significantly attenuates seizures in C57BL/6J mice exposed to moderate (20 mg/kg) and high (30 mg/kg) KA doses and tends to decrease mortality induced by the high KA dose. Histopathological evaluation of hippocampal (CA3 and CA1) and cortical areas of mice treated with 20 mg/kg KA shows that EmtinB treatment reduces KA-induced neurodegeneration in the CA1 region. These findings establish EmtinB as a promising target for therapeutic development.
Subject(s)
Kainic Acid/antagonists & inhibitors , Metallothionein/agonists , Neuroprotective Agents/pharmacokinetics , Neurotoxins/antagonists & inhibitors , Peptides/pharmacokinetics , Animals , Blood-Brain Barrier/drug effects , Blood-Brain Barrier/metabolism , Cells, Cultured , Cerebral Cortex/drug effects , Cerebral Cortex/pathology , Cerebral Cortex/physiopathology , Disease Models, Animal , Dose-Response Relationship, Drug , Epilepsy, Temporal Lobe/drug therapy , Epilepsy, Temporal Lobe/metabolism , Epilepsy, Temporal Lobe/physiopathology , Hippocampus/drug effects , Hippocampus/pathology , Hippocampus/physiopathology , Intercellular Signaling Peptides and Proteins , Kainic Acid/toxicity , Male , Metallothionein/metabolism , Mice , Mice, Inbred C57BL , Nerve Degeneration/chemically induced , Nerve Degeneration/drug therapy , Nerve Degeneration/physiopathology , Neuroprotective Agents/blood , Neuroprotective Agents/therapeutic use , Neurotoxins/toxicity , Peptides/blood , Peptides/therapeutic use , Rats , Rats, Wistar , Seizures/chemically induced , Seizures/drug therapy , Seizures/physiopathologyABSTRACT
The neural cell adhesion molecule (NCAM) plays a pivotal role in brain plasticity. Brain plasticity itself has a crucial role in the development of depression. The aim of this study was to analyze whether NCAM-deficient (NCAM(-/-)) mice exhibit depression-like behaviour and whether a peptide termed FGL, derived from the NCAM binding site for the fibroblast growth factor (FGF) receptor, is able to reverse the depression-like signs in NCAM(-/-) mice. Our study showed that NCAM(-/-) mice demonstrated increased freezing time in the tail-suspension test and reduced preference for sucrose consumption in the sucrose preference test, reduced adult neurogenesis in the dentate gyrus and reduced levels of the phosphorylated cAMP response element-binding protein (pCREB) in the hippocampus. FGL administered acutely or repeatedly reduced depression-like behaviour in NCAM(-/-) mice without having an effect on their wild-type littermates. Repeated administration of FGL enhanced survival of the newly born neurons in NCAM(-/-) mice and increased the levels of pCREB in both NCAM(+/+) and NCAM(-/-) mice. In conclusion, our data demonstrate that NCAM deficiency in mice results in a depression-like phenotype which can be reversed by the acute or repeated administration of FGL. The results also suggest a role of the deficit in NCAM signalling through the FGF receptor in depression.
