Brain transplants of cells expressing the carboxyl-terminal fragment of the Alzheimer amyloid protein precursor cause specific neuropathology in vivo.

Abstract

PC12 cells transfected with retroviral recombinants expressing the carboxyl-terminal 104 amino acids ofthe Alzheimer amyloid protein precursor (QAPP-C104) or PC12 cells transfected with the retroviral vector (DO) alone were transplanted into the brains of newborn mice. At 20 days after grafting, transplants could be detected in -all of the mouse brains examined. At 4 months after transplantation, experimental animals exhibited significant cortical atrophy. Some also revealed immunoreactivity with Alz-50, an antibody that detects an Alzheimer disease-related protein, in the somatodendritic domain of neurons in the cortex surrounding the transplants. In addition, disorganization of the neuropil in the CA2/3 region of the hippocampus ipsilateral to the transplant was revealed by staining with an antibody to the carboxylterminal end of the amyloid protein precursor. A decrease in cell body immunoreactivity for this portion of the amyloid protein precursor was also detected with this antibody. Together, these results suggest that the carboxyl-terminal fragment of I3APP may cause specific neuropathology and neurodegeneration in vivo.One of the hallmarks of Alzheimer disease pathology is the deposition of amyloid in neuritic plaques and along the walls of the cerebral vasculature (1-4). The principal component of amyloid is a 4-kDa protein termed 83/A4 (5-7). Recent evidence indicates that normal processing of the amyloid protein precursor (,8APP) is a membrane-associated event that occurs within the extracellular domain of f3/A4 (8,9). Hence, the generation of 8/A4 in Alzheimer disease appears to be the result of abnormal cleavage. However, the molecular mechanisms of amyloidogenesis, as well as the role of amyloidogenesis in the development of Alzheimer disease pathology, remain unclear.Recent evidence has implicated a carboxyl-terminal fragment of f3APP in the processes of amyloidogenesis and neurodegeneration. This fragment, which spans the f3/A4 and cytoplasmic domains, has a tendency to self-aggregate (10). Moreover, expression of this carboxyl-terminal 3APP fragment in primate cells has been shown to lead to the production of a 16-kDa protein that aggregates and accumulates into deposit-like structures (11) and to result in the formation of amyloid-like fibrils (12).We have shown that this same carboxyl-terminal I3APP fragment is neurotoxic (13). PC12 cells transfected with a retroviral recombinant expressing the carboxyl-terminal 104 amino acids of SAPP (formerly termed AB1, ref. 13; now termed /3APP-C104) degenerate when induced to differentiate into neuronal cells with nerve growth factor (13). To test the hypothesis that this neurotoxic carboxyl-terminal f3APP fragment may play a role not only in amyloidogenesis but also in the development of the progressive neuropathology of Alzheimer disease, we transplanted cells expressing this fragment into the brains of newborn mice. We report here that animals transplanted with 8APP-104-transfected PC12 cells exhibited gross cortical atrophy by 4 months after ...

An Etiological Role of Amyloidogenic Carboxyl‐Terminal Fragments of the β‐Amyloid Precursor Protein in Alzheimer's Disease

“…In AD and related disorders such as Down's syndrome, excessive production of /IAPP and/or reduction of some endosomal/lysosomal activities may induce accumulation of amyloidogenic CT fragments of /IAPP in the neuron and/or near the membrane Neve et al, 1992), and these CT fragments may kill the neurons, probably through the formation of non-ion-selective channels or pores in the cell membrane from inside the cells (Fraser et al, 1996;Hartell and Suh, 1996) (Fig. 1).…”

“…CT fragments with molecular masses of 12-16 kDa have also been found in media and cytosol of lymphoblastoid cells obtained from patients with earlyor late-onset FAD (Matsumoto, 1994) and Down's syndrome (Kametani et al, 1994). Finally, several transfection studies have correlated production of the A/I-bearing CT fragment with neurotoxicity (Yankner et al, 1989;Fukuchi et al, 1992a Fukuchi et al, ,b, 1993Neve et al, 1992;Yoshikawa et al, 1992); whereas recent transgenic animal experiments using CT 100 peptide have linked CT fragment production with neurodegeneration Arters et al, 1995;Howland et al, 1995;Oster-Granite et al, 1996).In addition, this amyloidogenic CT peptide is expressed not only in the extracellular fluid of some FAD and Down' s syndrome cells but is also secreted in the media of PCI2 cells transfected with CT 104 and human mixed-brain cell cultures (Yankner et al, 1989;Seubert et al, 1993;Matsumoto, 1994;.It has been recently demonstrated that either extracellular or intracellular application of CT 105 elicited strong nonselective inward currents and toxic effects in Xenopus oocytes (Fraser et al, 1996), in rat Purkinje neurons (Hartell and Suh, 1996), and in PC 12 and cultured rat cortical cells . The channel-inducing and toxic activity of CT 105 was much more potent than that of any A/I fragments.…”

“…CT fragments with molecular masses of 12-16 kDa have also been found in media and cytosol of lymphoblastoid cells obtained from patients with earlyor late-onset FAD (Matsumoto, 1994) and Down's syndrome (Kametani et al, 1994). Finally, several transfection studies have correlated production of the A/I-bearing CT fragment with neurotoxicity (Yankner et al, 1989;Fukuchi et al, 1992a Fukuchi et al, ,b, 1993Neve et al, 1992;Yoshikawa et al, 1992); whereas recent transgenic animal experiments using CT 100 peptide have linked CT fragment production with neurodegeneration Arters et al, 1995;Howland et al, 1995;Oster-Granite et al, 1996).…”

The Functions of the Amyloid Precursor Protein Gene and Its Derivative Peptides: II Experimental Evidence and Clinical Studies

“…Adults, the aged, and patients with AD had similar splicing patterns [330]. An increase in the APP transcript lacking the Aβ sequence has been reported [281].…”

“…Retroviral expression of a C-terminal fragment containing the Aβ region in PC12 cells, when injected into the brains of newborn mice, caused atrophy of the cerebral cortex [281].…”