Protein Phosphatase 2A Catalytic Subunit α (PP2Acα) Maintains Survival of Committed Erythroid Cells in Fetal Liver Erythropoiesis through the STAT5 Pathway
Open accessAbstract
Suppression of programmed cell death is critical for the final maturation of red blood cells and depends largely on the anti-apoptotic effects of EpoR-STAT5-Bcl-x(L) signaling. As the major eukaryotic serine/threonine phosphatase, protein phosphatase 2A (PP2A) regulates multiple cellular processes, including apoptosis. However, whether PP2A plays a role in preventing erythroid cells from undergoing apoptosis remains to be elucidated. We conditionally inactivated the catalytic subunit α of PP2A (PP2Acα), which is the predominant form of PP2Ac, during early embryonic hematopoiesis. Loss of PP2Acα in hematopoietic cells perturbed definitive erythropoiesis characterized by fetal liver atrophy, reduced Ter119(+) cell number, abnormal expression patterns of molecular markers, less colony formation, and a reduction in definitive globin expression. Levels of erythropoiesis-promoting cytokines and initial seeding with hematopoietic progenitors remained unchanged in PP2Acα(TKO) fetal livers. We noted impaired expansion of the fetal erythroid compartment, which was associated with increased apoptosis of committed erythroid cells. Mechanistically, PP2Acα depletion markedly reduced Tyr(694) phosphorylation of STAT5 and expression of Bcl-x(L). Unexpectedly, PP2Acα-deficient embryos did not manifest any early embryonic vascular defects. Collectively, these data provide direct loss-of-function evidence demonstrating the importance of PP2Acα for the survival of committed erythroid cells during fetal liver erythropoiesis.
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Primitive erythropoiesis was normal, but definitive erythropoiesis was impaired, as witnessed by increased pro-erythroblasts, decreased erythroid colony- and blast-forming units, and reduced β maj/min-globin expression.
“Specifically, primitive erythropoiesis was normal, but definitive erythropoiesis was impaired, as witnessed by an increased number of pro-erythroblasts, a decreased number of erythroid colony-and blast-forming units and reduced expression of β maj/min -globin.”
From Physiologic functions of PP2A: Lessons from genetically modified mice (2019) · cites this paper as [38]
At E12.5 and E14.5, total cellularity of fetal liver was dramatically reduced, with a pronounced 90% reduction in erythrocytes, while other hematopoietic lineages appeared in normal numbers.
“At E12.5 and E14.5, total cellularity of fetal liver was dramatically reduced, with a pronounced 90% reduction in erythrocytes, while other hematopoietic lineages appeared in normal numbers.”
From Physiologic functions of PP2A: Lessons from genetically modified mice (2019) · cites this paper as [38]
Conditional knockout of Cα in early hematopoietic and endothelial cells caused embryos to look pale and die at E12.5 due to defects in hematopoiesis, despite incomplete knockout and 35% remaining PP2A activity in fetal livers.
“Another function of PP2A during embryonic development was revealed in a conditional KO model of Cα in early hematopoietic and endothelial cells [38].Homozygously targeted embryos looked pale and died at E12.5 due to defects in hematopoiesis, despite an incomplete KO and 35% remaining PP2A activity in fetal livers.”
From Physiologic functions of PP2A: Lessons from genetically modified mice (2019) · cites this paper as [38]
Increased apoptosis of committed erythroid cells was observed, correlating with decreased STAT5 phosphorylation (Tyr694) and decreased Bcl-XL expression in basal and EPO-stimulated cells.
“In addition, increased apoptosis of committed erythroid cells was observed, correlating with decreased STAT5 phosphorylation (Tyr694) and decreased Bcl-X L expression in basal and EPO-stimulated cells [38].”
From Physiologic functions of PP2A: Lessons from genetically modified mice (2019) · cites this paper as [38]
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- Authors
- Chen, W., Gu, P., Jiang, X., Ruan, H.-B., Li, C., & Gao, X.
- Affiliations
- Model Animal Research Center (CN)
- Corresponding author
- Gao, Xiang
- Venue
- The American Journal of Pathology
- Publisher
- Elsevier BV
- Published
- 2011-05
- Volume
- 178
- Issue
- 5
- Pages
- 2333-2343
- ISSN
- 0002-9440 (ISSN-L)
- PMC
- PMC3081176
- OpenAlex
- W1996756747
- Cited by
- 30
- References
- 63
- Citations by year
- 2025: 2 · 2024: 5 · 2023: 2 · 2022: 1 · 2021: 2 · 2020: 1 · 2019: 2 · 2018: 4 · 2017: 1 · 2016: 5 · 2015: 4
- FWCI
- 0.22
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- Locations
- American Journal Of Pathology (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Ministry of Science and Technology of the People's Republic of China (2005CB522501, 2006BAI23B00, 2006CB943500)
- National Science Foundation (30825024)
- Topics
- Health Sciences › Medicine › Hematology › Erythropoietin and Anemia Treatment
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Tyrosine Phosphatases
- Health Sciences › Medicine › Hematology › Hematopoietic Stem Cell Transplantation
- Keywords
- protein phosphatase 2A, erythropoiesis, fetal liver, apoptosis, STAT5 phosphorylation, Bcl-xL, erythropoietin receptor signaling, definitive erythropoiesis, conditional knockout, hematopoiesis
- MeSH terms
- Protein Phosphatase 2C, Animals, Cell Separation, Embryo, Mammalian, Erythropoiesis, Flow Cytometry, Immunohistochemistry, Liver, Phosphoprotein Phosphatases, Blotting, Western, Signal Transduction, Reverse Transcriptase Polymerase Chain Reaction, Erythroid Cells, STAT5 Transcription Factor, Mice
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