title: The onset of p53-dependent apoptosis plays a role in terminal differentiation of human normoblasts.
abstract: The p53 tumor suppressor gene was found to play a role in the differentiation of several tissue types. We report here that p53-dependent apoptosis plays a role in the final stages of physiological differentiation of normoblasts, resulting in nuclear condensation and expulsion without cell death. Blood samples of healthy newborns, cord blood as well as bone marrow, were analysed for apoptosis by TUNEL and p53 expression by immunostaining. While some samples exhibited simultaneously several distinct patterns of apoptosis, such as perinuclear, diffused nuclear or nuclear apoptotic bodies, others presented a single defined pattern. Overexpression of p53 protein was detected in normoblasts exhibiting either perinuclear or diffused nuclear p53, corresponding to the nuclear apoptotic pattern in the same sample. Similar results were also evident with colonies cultivated for 12-14 days in culture. Differentiated erythroid colonies exhibited overexpression of p53 and positive TUNEL staining only in the normoblasts. We further examined the state of caspase 3/7 and observed a decrease of this activated enzyme during erythroid differentiation in culture. This study suggests a novel role for apoptosis in normoblast differentiation where nuclear degradation occurs with a delay in the actual cell death. A pivotal role for the p53-dependent apoptosis in the erythroid lineage development is implied. However, this apoptotic process is not fully executed because of the exhaustion in caspase 3/7 and thus cells are diverted towards final stages of differentiation.
authors.affiliation: Department of Hematology, Assaf Harofeh Medical Center, Zerifin 70300, Israel. SPELLER@asaf.health.gov.il
authors.forename: Shoshana
authors.initials: S
authors.lastname: Peller
authors.forename: Jenny
authors.initials: J
authors.lastname: Frenkel
authors.forename: Tsvee
authors.initials: T
authors.lastname: Lapidot
authors.forename: Joy
authors.initials: J
authors.lastname: Kahn
authors.forename: Naomi
authors.initials: N
authors.lastname: Rahimi-Levene
authors.forename: Rivka
authors.initials: R
authors.lastname: Yona
authors.forename: Lior
authors.initials: L
authors.lastname: Nissim
authors.forename: Naomi
authors.initials: N
authors.lastname: Goldfinger
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Sherman
authors.forename: Varda
authors.initials: V
authors.lastname: Rotter
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases / Q000378:metabolism; D016923:Cell Death; D002454:Cell Differentiation / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D004900:Erythroblasts / Q000473:pathology* / Q000502:physiology; D005312:Fetal Blood / Q000166:cytology; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
chemical_list: D016159:Tumor Suppressor Protein p53; C505407:CASP3 protein, human; C505520:CASP7 protein, human; D053148:Caspase 3; D053179:Caspase 7; D020169:Caspases