Role of DDC-4/sFRP-4, a secreted frizzled-related protein, at the onset of apoptosis in mammary involution.
Using differential display, we isolated DDC-4, a secreted frizzled-related protein (sFRP), which is induced in the physiological apoptosis of hormonally regulated, reproductive tissues such as mammary gland, prostate, corpus luteum and uterus. The role of this gene in apoptosis was studied in animals overexpressing ectopic DDC-4/sFRP-4. Transgenic mice bearing the DDC-4/sFRP-4 cDNA under the control of the MMTV-LTR promoter showed lactational insufficiency and many apoptotic cells in the alveoli between day 19 of pregnancy and day 4 of lactation as demonstrated by TUNEL reaction and the presence of activated caspase-3. We performed a PKB/Akt kinase assay and studied several of its substrates using phosphorylation-specific antibodies to show reduced phosphorylation in PKB/Akt itself, as well as in glycogen synthetase kinase-3beta (GSK-3beta), BAD, and Forkhead. Taken together, our results show a role for DDC-4/sFRP-4 in abrogating an epithelial cell survival pathway at the onset of mammary gland involution.
Department of Clinical Research, University of Berne, Tiefenaustrasse 120, CH-3004 Bern, Switzerland.
M D
MD
Lacher
A
A
Siegenthaler
R
R
Jäger
Xi
X
Yan
S
S
Hett
L
L
Xuan
S
S
Saurer
R R
RR
Lareu
A M
AM
Dharmarajan
R
R
Friis
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D051858:Forkhead Transcription Factors; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D047908:Intracellular Signaling Peptides and Proteins; D008321:Mammary Glands, Animal / Q000166:cytology / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D009687:Nuclear Proteins / Q000378:metabolism; D010641:Phenotype; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011506:Proteins / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D014157:Transcription Factors / Q000378:metabolism; D019076:Transgenes / Q000235:genetics; D051025:bcl-Associated Death Protein; D000099274:Frizzled-Related Proteins; D000094742:Secreted Frizzled-Related Proteins
D002352:Carrier Proteins; D053148:Caspase 3; D020169:Caspases; D051858:Forkhead Transcription Factors; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D014157:Transcription Factors; D051025:bcl-Associated Death Protein; D000099274:Frizzled-Related Proteins; C494820:Bad protein, mouse; C498455:Sfrp4 protein, rat; D000094742:Secreted Frizzled-Related Proteins; C000605507:Gsk3b protein, mouse; C000605508:Gsk3b protein, rat; C505409:Casp3 protein, mouse; C505410:Casp3 protein, rat