title: Absence of colony stimulation factor-1 receptor results in loss of microglia, disrupted brain development and olfactory deficits.
abstract: The brain contains numerous mononuclear phagocytes called microglia. These cells express the transmembrane tyrosine kinase receptor for the macrophage growth factor colony stimulating factor-1 (CSF-1R). Using a CSF-1R-GFP reporter mouse strain combined with lineage defining antibody staining we show in the postnatal mouse brain that CSF-1R is expressed only in microglia and not neurons, astrocytes or glial cells. To study CSF-1R function we used mice homozygous for a null mutation in the Csflr gene. In these mice microglia are >99% depleted at embryonic day 16 and day 1 post-partum brain. At three weeks of age this microglial depletion continues in most regions of the brain although some contain clusters of rounded microglia. Despite the loss of microglia, embryonic brain development appears normal but during the post-natal period the brain architecture becomes perturbed with enlarged ventricles and regionally compressed parenchyma, phenotypes most prominent in the olfactory bulb and cortex. In the cortex there is increased neuronal density, elevated numbers of astrocytes but reduced numbers of oligodendrocytes. Csf1r nulls rarely survive to adulthood and therefore to study the role of CSF-1R in olfaction we used the viable null mutants in the Csf1 (Csf1(op)) gene that encodes one of the two known CSF-1R ligands. Food-finding experiments indicate that olfactory capacity is significantly impaired in the absence of CSF-1. CSF-1R is therefore required for the development of microglia, for a fully functional olfactory system and the maintenance of normal brain structure.
authors: Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, New York, New York, United States of America.
authors: Bryna
authors: B
authors: Erblich
authors: Liyin
authors: L
authors: Zhu
authors: Anne M
authors: AM
authors: Etgen
authors: Kostantin
authors: K
authors: Dobrenis
authors: Jeffrey W
authors: JW
authors: Pollard
mesh_terms: D000818:Animals; D001921:Brain / Q000254:growth & development* / Q000473:pathology; D051379:Mice; D017628:Microglia / Q000737:chemistry / Q000473:pathology*; D000857:Olfaction Disorders / Q000209:etiology*; D009833:Olfactory Pathways; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000032:analysis / Q000172:deficiency* / Q000502:physiology
chemical_list: D016186:Receptor, Macrophage Colony-Stimulating Factor