Zebrafish lacking Alzheimer presenilin enhancer 2 (Pen-2) demonstrate excessive p53-dependent apoptosis and neuronal loss.
Gamma-secretase cleavage, mediated by a complex of presenilin, presenilin enhancer (Pen-2), nicastrin, and Aph-1, is the final proteolytic step in generating amyloid beta protein found in brains of Alzheimer's disease patients and Notch intracellular domain critical for proper neuronal development. Here, we employ the zebrafish model to study the role of Pen-2 in neuronal survival. We found that (i) knockdown of Pen-2 using antisense morpholino led to a reduction of islet-1 positive neurons, (ii) Notch signaling was reduced in embryos lacking Pen-2 or other gamma-secretase components, (iii) neuronal loss in Pen-2 knockdown embryos is not as a result of a lack of neuronal precursor cells or cell proliferation, (iv) absence of Pen-2 caused massive apoptosis in the whole animal, which could be suppressed by simultaneous knockdown of the tumor suppressor p53, (v) loss of islet-1 or acetylated tubulin positive neurons in Pen-2 knockdown embryos could be partially rescued by knockdown of p53. Our results demonstrate that knockdown of Pen-2 directly induces a p53-dependent apoptotic pathway that contributes to neuronal loss and suggest that Pen-2 plays an important role in promoting neuronal cell survival and protecting from apoptosis in vivo.
Campbell
William A
WA
Center for Neurologic Diseases, Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA.
Yang
Hongwei
H
Zetterberg
Henrik
H
Baulac
Stéphanie
S
Sears
Jacqueline A
JA
Liu
Tianming
T
Wong
Stephen T C
ST
Zhong
Tao P
TP
Xia
Weiming
W
D000544:Alzheimer Disease; D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis / Q000235:genetics*; D015152:Blotting, Northern; D015153:Blotting, Western / Q000379:methods; D019521:Body Patterning / Q000187:drug effects / Q000235:genetics; D002452:Cell Count / Q000379:methods; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004625:Embryo, Nonmammalian; D029941:Fish Proteins / Q000737:chemistry / Q000172:deficiency / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000235:genetics*; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D020287:In Situ Nick-End Labeling / Q000379:methods; D007211:Indoles; D008565:Membrane Proteins / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism / Q000502:physiology*; D009474:Neurons / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D053766:Presenilin-2; D012333:RNA, Messenger / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000378:metabolism*; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000172:deficiency / Q000378:metabolism
D029941:Fish Proteins; D007211:Indoles; D008565:Membrane Proteins; D016376:Oligonucleotides, Antisense; D053766:Presenilin-2; D012333:RNA, Messenger; D051880:Receptors, Notch; D016159:Tumor Suppressor Protein p53; D029961:Zebrafish Proteins; C510149:psenen protein, zebrafish; C007293:DAPI