In Parkinson's disease, brain dopamine neurons degenerate most prominently in the substantia nigra. Neurotrophic factors promote survival, differentiation and maintenance of neurons in developing and adult vertebrate nervous system. The most potent neurotrophic factor for dopamine neurons described so far is the glial-cell-line-derived neurotrophic factor (GDNF). Here we have identified a conserved dopamine neurotrophic factor (CDNF) as a trophic factor for dopamine neurons. CDNF, together with its previously described vertebrate and invertebrate homologue the mesencephalic-astrocyte-derived neurotrophic factor, is a secreted protein with eight conserved cysteine residues, predicting a unique protein fold and defining a new, evolutionarily conserved protein family. CDNF (Armetl1) is expressed in several tissues of mouse and human, including the mouse embryonic and postnatal brain. In vivo, CDNF prevented the 6-hydroxydopamine (6-OHDA)-induced degeneration of dopaminergic neurons in a rat experimental model of Parkinson's disease. A single injection of CDNF before 6-OHDA delivery into the striatum significantly reduced amphetamine-induced ipsilateral turning behaviour and almost completely rescued dopaminergic tyrosine-hydroxylase-positive cells in the substantia nigra. When administered four weeks after 6-OHDA, intrastriatal injection of CDNF was able to restore the dopaminergic function and prevent the degeneration of dopaminergic neurons in substantia nigra. Thus, CDNF was at least as efficient as GDNF in both experimental settings. Our results suggest that CDNF might be beneficial for the treatment of Parkinson's disease.

Neurotrophic factors are promising candidates for the treatment of Parkinson's disease (PD). Mesencephalic astrocyte-derived neurotrophic factor (MANF) belongs to a novel evolutionarily conserved family of neurotrophic factors. We examined whether MANF has neuroprotective and neurorestorative effect in an experimental model of PD in rats. We also studied the distribution and transportation of intrastriatally injected MANF in the brain and compared it with glial cell line-derived neurotrophic factor (GDNF). Unilateral lesion of nigrostriatal dopaminergic system was induced by intrastriatal injection of 6-hydroxydopamine (6-OHDA). Amphetamine-induced turning behavior was monitored up to 12 weeks after the unilateral lesion. The local diffusion at the injection site and transportation profiles of intrastriatally injected MANF and GDNF were studied by immunohistochemical detection of the unlabeled growth factors as well as by autoradiographic and gamma counting detection of 125 I-labeled trophic factors. Intrastriatally injected MANF protected nigrostriatal dopaminergic nerves from 6-OHDA-induced degeneration as evaluated by counting tyrosine hydroxylase (TH)-positive cell bodies in the substantia nigra (SN) and TH-positive fibers in the striatum. More importantly, MANF also restored the function of the nigrostriatal dopaminergic system when administered either 6 h before or 4 weeks after 6-OHDA administration in the striatum. MANF was distributed throughout the striatum more readily than GDNF. The mechanism of MANF action differs from that of GDNF because intrastriatally injected 125 I-MANF was transported to the frontal cortex, whereas 125 I-GDNF was transported to the SN. Our results suggest that MANF is readily distributed throughout the striatum and has significant therapeutic potential for the treatment of PD.

Glial cell line-derived neurotrophic factor (GDNF) and a related protein, neurturin (NTN), require a GPI-linked coreceptor, either GFR alpha1 or GFR alpha2, for signaling via the transmembrane Ret tyrosine kinase. We show that mice lacking functional GFR alpha2 coreceptor (Gfra2-/-) are viable and fertile but have dry eyes and grow poorly after weaning, presumably due to malnutrition. While the sympathetic innervation appeared normal, the parasympathetic cholinergic innervation was almost absent in the lacrimal and salivary glands and severely reduced in the small bowel. Neurite outgrowth and trophic effects of NTN at low concentrations were lacking in Gfra2-/- trigeminal neurons in vitro, whereas responses to GDNF were similar between the genotypes. Thus, GFR alpha2 is a physiological NTN receptor, essential for the development of specific postganglionic parasympathetic neurons.

Amphoterin (HMGB1) is a 30-kD heparinbinding protein involved in process extension and migration of cells by a mechanism involving the receptor for advanced glycation end products (RAGE). High levels of amphoterin are released to serum during septic shock. We have studied the expression of amphoterin in monocytes and the role of amphoterin and RAGE in monocyte transendothelial migration. Unactivated monocytes in suspension did not reveal amphoterin on their surface, but adherent monocytes exported amphoterin to the cell surface. Immunohistochemical staining of arterial thrombi in vivo revealed amphoterin in mononuclear cells and in surrounding extracellular matrix. Amphoterin was secreted from phorbol ester and interferon-␥ (IFN-␥)-activated macrophages, and the secretion was inhibited by blocking the adenosine 5-triphosphate (ATP)-binding cassette transporter-1, a member of the multidrug resistance protein family. Amphoterin was specifically adhesive for monocytes in peripheral blood leukocyte adhesion assay. Adhesion caused an extensive spreading of cells, which was inhibited by the dominant-negative RAGE receptor (soluble ectodomain of RAGE), and adhesion up-regulated chromogranin expression in monocytes, also suggesting a RAGE-dependent interaction. Monocyte transendothelial migration was efficiently inhibited by anti-amphoterin and anti-RAGE antibodies and by the soluble RAGE. We suggest that amphoterin is an autocrine/paracrine regulator of monocyte invasion through the endothelium. IntroductionCirculating monocytes adhere to sites of vascular injury where they participate together with other cells in the regulation of blood clotting, inflammation, and wound healing. Adhesion to other cells and extracellular matrix components is a prerequisite for migration and tissue recruitment of monocytes. 1,2 The knowledge of molecules involved in monocyte transendothelial migration is rapidly increasing. However, the overall picture of the transendothelial migration mechanism is not completely understood. 2 Amphoterin is a 30-kD heparin-binding protein widely expressed in humans and other organisms, and it is abundantly expressed in the developing brain as well as in various immature and transformed cell lines. [3][4][5][6] It was isolated as an extracellular neurite outgrowth-promoting protein, but its amino acid sequence turned out to be identical to high-mobility groupϪ1 protein. 5,7 In a new nomenclature of high-mobility group proteins amphoterin and other proteins identical in the cDNA sequence are called as HMGB1 (high-mobility group B-1). 8 We have used the designation amphoterin for the protein occurring in the extracellular space and interacting with the cell surface. 5 Surface-bound amphoterin is adhesive for neural cells and platelets, and it induces extension of membrane processes in adherent cells. 3,9,10 Amphoterin binds to plasma membrane lipids, mainly to phosphatidylserine and sulfatide, and enhances and localizes plasminogen activation. 6,9,[11][12][13] In neurons, neurite outgrowth on amphoterin s...