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Updated: Jun 20, 2026
Mesenchymal Stem Cell Regulation of Macrophage Phagocytosis; Quantitation and Imaging
Published on: July 16, 2021
Modulation of expression and cellular distribution of p21 by macrophage migration inhibitory factor
Elliott Taranto1, Jin R Xue, Eric F Morand
1Centre for Inflammatory Diseases, Monash University Department of Medicine, Monash Medical Centre, Clayton, Melbourne, Australia. michelle.leech@med.monash.edu.au.
Background:
The pleiotropic protein MIF, (macrophage migration inhibitory factor), has been demonstrated to modulate several key proteins governing cell cycle control and is considered to contribute to cell growth and differentiation. In this study we investigated the effect of MIF on the expression and cellular distribution of the CDK inhibitor p21.
Methods:
The effect of endogenous MIF on p21 expression and distribution was examined by comparing murine dermal fibroblasts derived from wt and MIF -/- mice. The effect of MIF on cell growth and apoptotic rates was compared using 3H-Thymidine incorporation assays and annexin V/PI assays respectively. Total p21 protein levels were compared using flow cytometry and western blotting. p21 mRNA was assessed by RT-PCR. Intracellular p21 staining was performed to assess cellular distribution of total protein. To further confirm observations siRNA was used to knockdown MIF protein in wt cells. Cell cycle analysis was performed using PI incorporation assays.
Results:
MIF-/- murine dermal fibroblasts exhibited reduced proliferative responses and were more susceptible to apoptosis. This was associated with reduced p21 expression and nuclear distribution. Treatment with recombinant MIF protein was demonstrated to reduce both basal and induced apoptosis and increase nuclear p21 expression. Reduced nuclear p21 expression was also observed in MIF siRNA treated wt cells.
Conclusion:
The results demonstrate that in the absence of MIF p21 expression and nuclear distribution is reduced which is associated with a reduction in cell growth and increased apoptosis. MIF may therefore play a role in maintaining homeostatic control of p21.
Insights
Macrophage migration inhibitory factor (MIF) regulates cell growth and apoptosis by controlling p21 expression and nuclear distribution. Its absence reduces cell proliferation and increases susceptibility to cell death.
Area of Science:
- Cell Biology
- Molecular Biology
- Immunology
Background:
- Macrophage migration inhibitory factor (MIF) is a pleiotropic protein influencing cell cycle control, growth, and differentiation.
- MIF's role in regulating the cyclin-dependent kinase (CDK) inhibitor p21 requires further investigation.
Purpose of the Study:
- To investigate the effect of MIF on the expression and cellular distribution of p21.
- To determine MIF's impact on cell proliferation and apoptosis.
Main Methods:
- Comparison of wild-type (wt) and MIF-deficient (MIF-/-) murine dermal fibroblasts.
- Assays for cell proliferation (3H-Thymidine incorporation), apoptosis (annexin V/PI), protein levels (flow cytometry, western blotting), and mRNA expression (RT-PCR).
- siRNA-mediated knockdown of MIF in wt cells and analysis of p21 localization and cell cycle progression.
Main Results:
- MIF-/- fibroblasts showed reduced proliferation, increased apoptosis, and decreased p21 expression and nuclear localization.
- Recombinant MIF protein treatment reduced apoptosis and increased nuclear p21 expression.
- MIF knockdown in wt cells led to reduced nuclear p21 expression.
Conclusions:
- MIF deficiency leads to reduced p21 expression and nuclear distribution, correlating with decreased cell growth and increased apoptosis.
- MIF plays a crucial role in maintaining cellular homeostasis by regulating p21 expression and localization.
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