Advertisements
Feeds:
Posts
Comments

Posts Tagged ‘liver cells’


Biologists Wondered—How Old are Cells in an Organism?

Reporter: Irina Robu, PhD

Scientists form Salk Institute discovered that the mouse brain, live and pancreas contain populations of cells and proteins with extremely long lifespans with some as old as neurons. The research was published in Cell Metabolism on June 6, 2019. The general idea is that most neurons in the brain do not divide during adulthood and experience a long lifespan and age-related decline. Yet, due to limitations the lifespan of cells outside of the brain was difficult to determine.

However, the researchers knew very well that neurons are not replaced during the lifespan, they used them as control to compare other non-dividing cells. The team used an electron isotope labeling with hybrid imaging method to visualize and quantify cell and protein age and turnover in the brain, pancreas and liver in the young and old rodent models.

To confirm that their method is correct, the scientist determined first the age of the neurons and then realized that the cells that line blood vessels, endothelial cells were as old as neurons. According to this research, it means that some non-neuronal cells do not replicate themselves throughout the lifespan. The pancreas, the organ responsible for maintaining blood sugar levels and secreting digestive enzymes showed cells of all ages. Still, some beta cells, replicate during the lifetime and are relatively young, while others do not divide and were long lived. Yet, delta cells found in stomach do not divide at all.
Unlike other type of cells, the liver cells have the capacity to regenerate during adulthood. The researchers expected to observe young liver cells, however the majority of liver cells were found to be as old as the animal, while the cells that line blood vessels and stellate like cells, another liver type cell were short lived.

But on the molecular level, a selection of long-lived cells contains protein complexes displaying age mosaicism. Due to the modern visualizing technologies, scientists were able to pinpoint the age of the cells and their supra-molecular complexes precisely. The ultimate goal to determining the age of the cells and sub-cellular structures is to provide insights into cell maintenance and repair mechanism and utilize these mechanisms to prevent or delay old age-linked decline of organs with limited cell regeneration.

SOURCE

https://www.salk.edu/news-release/how-old-are-your-organs-to-scientists-surprise-organs-are-a-mix-of-young-and-old-cells/

Advertisements

Read Full Post »


Reprogramming Cell Fate

 

Reporter: Larry H.Bernstein, MD, FCAP

Kathy Liszewski: reporting Gordon Conference “Reprogramming Cell Fate” meeting
M. Azim Surani, Ph.D., Univ Cambridge
Source unknown: June 21, 2012;32(11)
They report two critical steps both of which are needed for exploring epigenetic reprogramming.  While females have two X chromosomes ,
  • the inactivation of one is necessary for cell differentiation.
  • Only after epigenetic reprogramming of the X chromosome can pluripotency be acquired.

Pluripotent stem cells can generate – any fetal or adult cell type but

    • don’t develop into a complete organism.
Pioneer transcription factors take the lead in – facilitating cellular reprogramming – and responses to environmental cues.
Multicellular organisms consist of
  • functionally distinct cellular types
  • produced by differential activation of gene expression.
They seek out and bind specific regulatory sequences in DNA, even though DNA is coated with and condensed into a thick fiber of chromatin.
The pioneer factor, discovered by Prof. KS Zaret at UPenn SOM in 1996, endows the competence for gene activity,
  • being among the first transcription factors to
  • engage and pry open the target sites in chromatin.
FoxA factors, expressed in the foregut endoderm of the mouse,are necessary for
  • induction of the liver program.
    •  nearly one-third of the DNA sites bound by FoxA in the adult liver occur near silent genes.
organ regeneration example from induced plurip...

organ regeneration example from induced pluripotent stem cells(iPS cell) (Photo credit: Wikipedia)

English: Pathway of stem cell differentiation

English: Pathway of stem cell differentiation (Photo credit: Wikipedia)

Read Full Post »