Mutations in the amyloid precursor protein (APP) gene cause early-onset familial Alzheimer disease (AD) by affecting the formation of the amyloid ␤ (A␤) peptide, the major constituent of AD plaques. We expressed human APP 751 containing these mutations in the brains of transgenic mice. Two transgenic mouse lines develop pathological features reminiscent of AD. The degree of pathology depends on expression levels and specific mutations. A 2-fold overexpression of human APP with the Swedish double mutation at positions 670͞671 combined with the V717I mutation causes A␤ deposition in neocortex and hippocampus of 18-month-old transgenic mice. The deposits are mostly of the diffuse type; however, some congophilic plaques can be detected. In mice with 7-fold overexpression of human APP harboring the Swedish mutation alone, typical plaques appear at 6 months, which increase with age and are Congo Red-positive at first detection. These congophilic plaques are accompanied by neuritic changes and dystrophic cholinergic fibers. Furthermore, inf lammatory processes indicated by a massive glial reaction are apparent. Most notably, plaques are immunoreactive for hyperphosphorylated tau, reminiscent of early tau pathology. The immunoreactivity is exclusively found in congophilic senile plaques of both lines. In the higher expressing line, elevated tau phosphorylation can be demonstrated biochemically in 6-month-old animals and increases with age. These mice resemble major features of AD pathology and suggest a central role of A␤ in the pathogenesis of the disease.

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We report the production of recombinant human lactoferrin in Aspergillus oryzae. Expression of human lactoferrin (hLF), a 78 kD glycoprotein, was achieved by placing the cDNA under the control of the A. oryzae alpha-amylase promoter and the 3' flanking region of the A. niger glucoamylase gene. Using this system, hLF is expressed and secreted into the growth medium at levels up to 25 mg/l. The recombinant lactoferrin is indistinguishable from human milk lactoferrin with respect to its size, immunoreactivity, and iron-binding capacity. The recombinant protein appears to be appropriately N-linked glycosylated and correctly processed at the N-terminus by the A. oryzae secretory apparatus. Lactoferrin is the largest heterologous protein and the first mammalian glycoprotein expressed in the Aspergillus system to date. Hence, this expression system appears suitable for the large-scale production and secretion of biologically active mammalian glycoproteins.