Myoglobin expression by alternative transcript in different mesenchymal stem cells compartments

Area of Science:

• Stem cell biology
• Mitochondrial metabolism
• Cellular bioenergetics

Background:

• Stem cell metabolic phenotype is linked to pluripotency, with mitochondrial and oxygen metabolism roles still being defined.
• Previous work identified ectopic myoglobin (MB) expression in hematopoietic stem/progenitor cells.
• This study investigates MB expression in mesenchymal stem cells (MSCs) from various tissues.

Purpose of the Study:

• To analyze myoglobin expression and its functional role in different types of mesenchymal stem cells.
• To compare the metabolic profiles and mitochondrial dynamics of neonatal versus adult MSCs.
• To explore the relationship between myoglobin expression, differentiation, and pluripotency.

Main Methods:

• Mesenchymal stem cells (MSCs) isolated from human placental membrane, mammary adipose tissue, and dental pulp.
• RT-PCR, Western blotting, and mass spectrometry used to detect myoglobin (MB) expression.
• Metabolic flux analysis and cyto-imaging employed to assess metabolic phenotype and mitochondrial dynamics.

Main Results:

• Myoglobin (MB) expression in MSCs is driven by an alternative transcript, with protein found in monomer and dimer forms.
• Neonatal MSCs exhibit more active bioenergetics than adult MSCs, correlating with MB-mitochondria co-localization.
• MB expression decreases during osteogenic differentiation but increases upon fibroblast reprogramming to induced pluripotent stem cells (iPSCs).

Conclusions:

• Ectopic myoglobin (MB) expression in non-muscle tissues suggests a role beyond oxygen storage, potentially in regulating aerobic metabolism and pluripotency.
• MB's modulation of mitochondrial physiology in stem cells offers new avenues for regenerative medicine and cancer stem cell therapy.
• Understanding MB's function in stem cell biology is crucial for future therapeutic applications.