SIRT1 synchs satellite cell metabolism with stem cell fate

Notch signaling was first discovered in Drosophila melanogaster, where it is involved in cell lineage differentiation. Notch signaling regulates the maintenance and differentiation of intestinal stem cells or ISCs by controlling the expression of atonal homolog 1 or Atoh1. Atoh1 directs cells to differentiate into secretory cells.
Direct cell-to-cell contact is needed for the activation of Notch signaling. The signal is initiated when a notch ligand binds to a receptor on an adjacent cell, also...

The intestinal epithelial lining rapidly renews every 4 to 5 days. The renewal is facilitated by intestinal stem cells (ISCs) located at the base of the crypt– a gland located at the bottom of each villus. ISCs divide asymmetrically to form new stem cells and progenitor daughter cells. The daughter cells are called transit-amplifying (TA) cells which move upwards along the crypt and either differentiate into absorptive cells– the enterocytes or secretory cells– including the...

Reprogramming alters the gene expression in somatic cells, transforming them into induced pluripotent stem (iPS) cells over several generations. Scientists can reprogram cells by introducing genes for four transcription factors—Oct4, Sox2, Klf4, and c-Myc (OSKM) by viral or non-viral methods. These factors are also known as Yamanaka factors after Shinya Yamanaka, who first generated iPS cells using mouse skin cells. Yamanaka was awarded the Nobel Prize in Physiology or Medicine in 2012...

The hematopoietic stem cells or HSCs are multipotent, meaning they can differentiate and give rise to all blood and immune cells. HSCs are maintained in the quiescent stage until an external stimulus initiates their differentiation. The multipotent HSCs exist as two heterogeneous populations, long-term repopulating cells (LTRC) and short-term repopulating cells (STRC). The two HSC populations have different surface markers or receptors and are classified based on quiescence and long-term...

The stem cell niche is the dynamic microenvironment where stem cells reside. Inside these niches, the cells may remain undifferentiated, undergo high self-renewal, or become lineage-specific progenitors. Stem cells coexist with other niche cells, such as stromal cells. They also interact closely with the ECM. Cell-cell and cell-matrix communication occur via adhesion molecules or soluble factors that signal the stem cells and determine their fate. Stromal cells also provide survival signals to...

Satellite stem cells or myosatellite cells are quiescent stem cells that Alexander Mauro first identified in 1961. These cells are located between the sarcolemma, the plasma membrane of muscle fibers, and the basal lamina, the connective tissue sheath covering it. These mononucleated cells are activated in response to muscle injury, can transform into myoblasts, and may form or repair muscle fibers. Myosatellite cells can provide additional myonuclei for muscle regeneration or return to a...