Identification of the neuroprotective molecular region of pigment epithelium-derived factor and its binding sites on motor neurons.
Pigment epithelium-derived factor (PEDF), a member of the serine protease inhibitor (serpin) family, is a survival factor for various types of neurons. We studied the mechanisms by which human PEDF protects motor neurons from degeneration, with the goal of eventually conducting human clinical trials. We first searched for a molecular region of human PEDF essential to motor neuron protection. Using a spinal cord culture model of chronic glutamate toxicity, we show herein that a synthetic 44 mer peptide from an N-terminal region of the human PEDF molecule that lacks the homologous serpin-reactive region contains its full neuroprotective activity. We also investigated the presence and distribution of PEDF receptors in the spinal cord. Using a fluoresceinated PEDF probe, we show that spinal motor neurons contain specific binding sites for PEDF. Kinetics analyses using a radiolabeled PEDF probe demonstrate that purified rat motor neurons contain a single class of saturable and specific binding sites. This study indicates that a small peptide fragment of the human PEDF molecule could be engineered to contain all of its motor neuron protective activity, and that the neuroprotective action is likely to be mediated directly on motor neurons via a single class of PEDF receptors. The data support the pharmacotherapeutic potential of PEDF as a neuroprotectant in human motor neuron degeneration.
Bilak
Masako M
MM
Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
Becerra
S Patricia
SP
Vincent
Andrea M
AM
Moss
Brian H
BH
Aymerich
Maria S
MS
Kuncl
Ralph W
RW
D000818:Animals; D001665:Binding Sites / Q000502:physiology; D001667:Binding, Competitive / Q000187:drug effects / Q000502:physiology; D002452:Cell Count; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D006224:Cricetinae; D005136:Eye Proteins; D018698:Glutamic Acid / Q000633:toxicity; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D009046:Motor Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009414:Nerve Growth Factors; D018696:Neuroprotective Agents / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000494:pharmacology; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology; D011506:Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism* / Q000493:pharmacokinetics; D011869:Radioligand Assay; D051381:Rats; D017207:Rats, Sprague-Dawley; D018013:Receptors, Neuropeptide / Q000378:metabolism; D015843:Serpins / Q000737:chemistry* / Q000378:metabolism* / Q000493:pharmacokinetics; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013329:Structure-Activity Relationship; D000099174:Pigment Epithelium-Derived Factor
D002795:Choline O-Acetyltransferase; D005136:Eye Proteins; D018698:Glutamic Acid; D007106:Immune Sera; D009414:Nerve Growth Factors; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D011506:Proteins; D018013:Receptors, Neuropeptide; D015843:Serpins; D000099174:Pigment Epithelium-Derived Factor; C400531:pigment epithelium-derived factor receptor