Amyloidosis causes downregulation of SorLA, SorCS1 and SorCS3 expression in mice.

Accumulation of ß-amyloid peptide (Aß) is regarded as a primary cause of Alzheimer's disease (AD). Aß is derived by sequential cleavage of the amyloid precursor protein (APP). Alterations in the subcellular targeting of APP are thought to affect the degree of Aß production. Sorting receptors, such as SorLA, convey subcellular targeting of APP. Dysfunction of SorLA, and likely of the related receptors SorCS1 and SorCS3, cause AD. Nevertheless, disease progression could also provoke altered expression of the receptors. Here, we assessed if Aß plaque formation promotes altered expression of SorLA, SorCS1 and SorCS3. We analyzed transcript levels during aging and after amyloidosis in brain areas characterized by early amyloid plaque formation in an AD mouse model (APPPS1) and wild types. We observed stable expression levels during aging (1-12 months). After plaque formation, SorCS1 and SorLA expression were markedly reduced in the frontal cerebral cortex and to a minor extent in the hippocampus, whereas SorCS3 expression was solely reduced in the frontal cerebral cortex. Our results indicate that disease progression, associated with Aß accumulation, can negatively regulate expression of the receptors.

The orphan G-protein-coupled receptor GPR19 is expressed predominantly in neuronal cells during mouse embryogenesis.

G-protein-coupled receptors (GPCRs) are characterized by seven transmembrane domains and constitute the largest and structurally best-conserved family of signaling molecules. They are present in a diversity of organs and tissues and are involved in virtually all physiological processes. Here we report the expression of GPR19, an orphan GPCR, during mouse embryonic development and in the adult brain. Transcripts of GPR19 were detected early in embryonic development and were prominent in tissues of neuroectodermal origin. With ongoing differentiation, the localization of GPR19 transcripts became restricted to distinct regions of the developing brain, and the overall signal intensity declined in parallel. In the adult mouse, GPR19 showed high levels of transcription in several regions of the brain, including the olfactory bulb, the hippocampus, hypothalamic nuclei, and the cerebellum, and in testis. Lower levels of GPR19 expression were detected in heart, liver, and kidney. These data suggest that, amongst several other functions in the adult organism, GPR19 probably exerts its most characteristic effects during the early development of the nervous system.

Isolation of a putative peroxidase, a target for factors controlling foot-formation in the coelenterate hydra.

In hydra, differentiated ectodermal cells of the foot region contain a peroxidase activity that can be used as a marker for foot-specific differentiation processes. Because the expression of the gene coding for the peroxidase must be tightly regulated during foot-specific differentiation, characterization of the protein and cloning of the corresponding gene should provide valuable tools for getting deeper insights into the regulation of foot-specific differentiation. In this paper we characterize the foot-specific peroxidase by biochemical, histochemical, and molecular biological methods. We show that it is localized in granules, and that it consists of a single component, the molecular mass of which is in the range of 43-45 kDa. Purification of the protein and subsequent cloning of its complementary DNA yielded two closely related clones, ppod1 and ppod2. Transcripts of ppod2 are abundant in the whole animal with the exception of the hypostome, the tentacles, and the foot; the expression of ppod1 matches exactly the localization of the foot-specific peroxidase.