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Increased apoptosis arising from increased expression of the Alzheimer's disease-associated presenilin-2 mutation (N141I).

Janicki S, Monteiro MJ - J. Cell Biol. (1997)

Bottom Line: As neither the normal function of either presenilin is known nor why mutations cause disease, we examined the properties of wild-type, truncated, and mutant PS-2 upon expression in HeLa cells.Moreover, the AD- associated PS-2 missense mutation (N141I) more efficiently induced cell death compared to wild-type PS-2 despite lower mutant protein accumulation.We hypothesize that full-length but not cleaved PS-2 may be important in the regulation or induction of apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Medical Biotechnology Center of the University of Maryland Biotechnology Institute, Baltimore, Maryland 21201, USA.

ABSTRACT
Mutations in the genes for presenilin 1 and 2 (PS-1 and PS-2) have been linked to development of early-onset Alzheimer's disease (AD). As neither the normal function of either presenilin is known nor why mutations cause disease, we examined the properties of wild-type, truncated, and mutant PS-2 upon expression in HeLa cells. Although HeLa cells are strongly predisposed to continued mitosis, expression of PS-2 induced programmed cell death (apoptosis). Direct evidence for apoptosis was obtained by double staining for terminal deoxynucleotide transferase nick end labeling (TUNEL) and PS-2 expression and by following green fluorescent protein-tagged PS-2 over time. Deletion analysis indicates that as little as 166 NH2-terminal residues of PS-2 are sufficient for endoplasmic reticulum (ER) localization and apoptosis. Moreover, the AD- associated PS-2 missense mutation (N141I) more efficiently induced cell death compared to wild-type PS-2 despite lower mutant protein accumulation. Expression of the presenilins in several other cell lines and transgenic mice has been accompanied by rapid protein cleavage without the induction of cell death. In contrast, PS-2 expressed in HeLa cells was not cleaved, and cell death occurred. We hypothesize that full-length but not cleaved PS-2 may be important in the regulation or induction of apoptosis.

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Schematic drawings of PS-2 expression constructs. The  putative structure of PS-2 is shown. The schematic with a corresponding line drawing illustrates PS-2 with eight TMDs (numbered 1–8). NH2-, COOH-terminal, and the large hydrophilic loop  domains are all present on the cytoplasmic side of an ER membrane. (A–I) PS-2 expression constructs used in this study. Some  of the restriction sites used for cloning are shown. Transcription  of all constructs was driven by the CMV promoter. The constructs that were myc- or GFP-tagged are illustrated. Constructs  B and I contain the AD-associated PS-2(N141I) mutation. Construct J is a line drawing of the Kv1.4 human potassium channel  cDNA that was used as a control since it is similar in topology  (shown schematically) to PS-2.
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Figure 1: Schematic drawings of PS-2 expression constructs. The putative structure of PS-2 is shown. The schematic with a corresponding line drawing illustrates PS-2 with eight TMDs (numbered 1–8). NH2-, COOH-terminal, and the large hydrophilic loop domains are all present on the cytoplasmic side of an ER membrane. (A–I) PS-2 expression constructs used in this study. Some of the restriction sites used for cloning are shown. Transcription of all constructs was driven by the CMV promoter. The constructs that were myc- or GFP-tagged are illustrated. Constructs B and I contain the AD-associated PS-2(N141I) mutation. Construct J is a line drawing of the Kv1.4 human potassium channel cDNA that was used as a control since it is similar in topology (shown schematically) to PS-2.

Mentions: Both presenilin genes are ubiquitously expressed with differential accumulation of two major mRNA transcripts (Li et al., 1995; Rogaev et al., 1995; Sherrington et al., 1995; Lee et al., 1996; Vito et al., 1996a,b). Immunofluorescence staining of epitope-tagged presenilins indicates that the proteins are localized to the ER and Golgi, although subtle differences in localization between PS-1 and PS-2 were noted (Cook et al., 1996; Kovacs et al., 1996; Walter et al., 1996). The presenilins are multipass transmembrane proteins that are believed to topologically weave through ER membranes six to eight times with the NH2- and COOH-terminal domains and the large “loop” spanning the putative sixth and seventh transmembrane domains (TMDs) (according to some models) contained within the cytoplasm (see Fig. 1; Doan et al., 1996; Li and Greenwald, 1996; Lehmann et al., 1997). Recent studies of PS-1 expression in fibroblasts and transgenic mice indicate that PS-1 is proteolytically cleaved since 27–28-kD NH2-terminal and 16– 17-kD COOH-terminal derivatives accumulate in cell lysates (Lee et al., 1996; Thinakaran et al., 1996). Analogous proteolytic cleavage of PS-2 has also been reported (Kim et al., 1997; Tomita et al., 1997). The function of proteolytic cleavage of the presenilins is not known.


Increased apoptosis arising from increased expression of the Alzheimer's disease-associated presenilin-2 mutation (N141I).

Janicki S, Monteiro MJ - J. Cell Biol. (1997)

Schematic drawings of PS-2 expression constructs. The  putative structure of PS-2 is shown. The schematic with a corresponding line drawing illustrates PS-2 with eight TMDs (numbered 1–8). NH2-, COOH-terminal, and the large hydrophilic loop  domains are all present on the cytoplasmic side of an ER membrane. (A–I) PS-2 expression constructs used in this study. Some  of the restriction sites used for cloning are shown. Transcription  of all constructs was driven by the CMV promoter. The constructs that were myc- or GFP-tagged are illustrated. Constructs  B and I contain the AD-associated PS-2(N141I) mutation. Construct J is a line drawing of the Kv1.4 human potassium channel  cDNA that was used as a control since it is similar in topology  (shown schematically) to PS-2.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139804&req=5

Figure 1: Schematic drawings of PS-2 expression constructs. The putative structure of PS-2 is shown. The schematic with a corresponding line drawing illustrates PS-2 with eight TMDs (numbered 1–8). NH2-, COOH-terminal, and the large hydrophilic loop domains are all present on the cytoplasmic side of an ER membrane. (A–I) PS-2 expression constructs used in this study. Some of the restriction sites used for cloning are shown. Transcription of all constructs was driven by the CMV promoter. The constructs that were myc- or GFP-tagged are illustrated. Constructs B and I contain the AD-associated PS-2(N141I) mutation. Construct J is a line drawing of the Kv1.4 human potassium channel cDNA that was used as a control since it is similar in topology (shown schematically) to PS-2.
Mentions: Both presenilin genes are ubiquitously expressed with differential accumulation of two major mRNA transcripts (Li et al., 1995; Rogaev et al., 1995; Sherrington et al., 1995; Lee et al., 1996; Vito et al., 1996a,b). Immunofluorescence staining of epitope-tagged presenilins indicates that the proteins are localized to the ER and Golgi, although subtle differences in localization between PS-1 and PS-2 were noted (Cook et al., 1996; Kovacs et al., 1996; Walter et al., 1996). The presenilins are multipass transmembrane proteins that are believed to topologically weave through ER membranes six to eight times with the NH2- and COOH-terminal domains and the large “loop” spanning the putative sixth and seventh transmembrane domains (TMDs) (according to some models) contained within the cytoplasm (see Fig. 1; Doan et al., 1996; Li and Greenwald, 1996; Lehmann et al., 1997). Recent studies of PS-1 expression in fibroblasts and transgenic mice indicate that PS-1 is proteolytically cleaved since 27–28-kD NH2-terminal and 16– 17-kD COOH-terminal derivatives accumulate in cell lysates (Lee et al., 1996; Thinakaran et al., 1996). Analogous proteolytic cleavage of PS-2 has also been reported (Kim et al., 1997; Tomita et al., 1997). The function of proteolytic cleavage of the presenilins is not known.

Bottom Line: As neither the normal function of either presenilin is known nor why mutations cause disease, we examined the properties of wild-type, truncated, and mutant PS-2 upon expression in HeLa cells.Moreover, the AD- associated PS-2 missense mutation (N141I) more efficiently induced cell death compared to wild-type PS-2 despite lower mutant protein accumulation.We hypothesize that full-length but not cleaved PS-2 may be important in the regulation or induction of apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Medical Biotechnology Center of the University of Maryland Biotechnology Institute, Baltimore, Maryland 21201, USA.

ABSTRACT
Mutations in the genes for presenilin 1 and 2 (PS-1 and PS-2) have been linked to development of early-onset Alzheimer's disease (AD). As neither the normal function of either presenilin is known nor why mutations cause disease, we examined the properties of wild-type, truncated, and mutant PS-2 upon expression in HeLa cells. Although HeLa cells are strongly predisposed to continued mitosis, expression of PS-2 induced programmed cell death (apoptosis). Direct evidence for apoptosis was obtained by double staining for terminal deoxynucleotide transferase nick end labeling (TUNEL) and PS-2 expression and by following green fluorescent protein-tagged PS-2 over time. Deletion analysis indicates that as little as 166 NH2-terminal residues of PS-2 are sufficient for endoplasmic reticulum (ER) localization and apoptosis. Moreover, the AD- associated PS-2 missense mutation (N141I) more efficiently induced cell death compared to wild-type PS-2 despite lower mutant protein accumulation. Expression of the presenilins in several other cell lines and transgenic mice has been accompanied by rapid protein cleavage without the induction of cell death. In contrast, PS-2 expressed in HeLa cells was not cleaved, and cell death occurred. We hypothesize that full-length but not cleaved PS-2 may be important in the regulation or induction of apoptosis.

Show MeSH
Related in: MedlinePlus