Adult Neurogenesis and Stem Cells

A collection of flashcards summarizing key vocabulary and concepts pertaining to adult neurogenesis and stem cells.

Neurogenesis

The process of generating new neurons in the brain.

Hippocampus

A region of the brain crucial for learning and memory, and one of the primary sites of neurogenesis in adults.

BrdU (bromo-deoxy-uridine)

A compound used as a marker to identify newly born cells by incorporating into the DNA of dividing cells.

Factors that Promote Neurogenesis

Conditions such as exercise and enriched environments that enhance the production of new neurons.

Factors that Inhibit Neurogenesis

Conditions such as high stress and elevated glucocorticoids like cortisol that suppress the generation of new neurons.

BDNF (brain-derived neurotrophic factor)

A growth factor that supports the survival of existing neurons and promotes the differentiation of new neurons.

Pluripotent Stem Cells

Stem cells that have the potential to differentiate into any cell type in the body, typically found early in development.

Multipotent Stem Cells

Stem cells that can differentiate into a limited number of cell types within a specific tissue family.

Induced Pluripotent Stem Cells (IPSCs)

Adult cells that have been reprogrammed back into a pluripotent state, allowing them to generate any cell type needed for treatment.

Retrovirus

A type of virus used to introduce stem cell-associated genes into mature cells during the reprogramming process.

Curing Sickle Cell Anemia

An application of IPSCs where skin cells are reprogrammed and differentiated to correct the genetic mutation causing the disease.

Ethical Issues in IPSCs

Concerns about the implications of using retroviruses for reprogramming and the potential for creating genetically manipulated cells.

Tumors and IPSCs

A limitation of IPSCs, where some cells developed tumors due to the retrovirus integration into the DNA.

Disease Modeling using IPSCs

Using patient-derived IPSCs to study specific diseases and develop treatment strategies.

Nervous system development (beginning)

at 18 days when the fells of the ectoderm start proliferating to form a neural plate

Ectoderm

Outer layer of tissue in the embryo which is going to develop into skin BUT part of it is also going to develop into the nervous system

Neural groove

Formed days later when the neural plate forms around the edges. By 22 days of gestation it will close form the neural tube

Ventricular system

Connected system that includes the central canal of the spinal cord and also the ventricles of the brain (Neurogenesis is going to take place at the ventricular zone of the neural tube)

Neural tube

Inside border of the neural tube (zone of mitosis)

Generation of neurons developing into 3

Prosencephalon (forebrain)

Mesencephalon (midbrain)

Rhombencephalon (hindbrain)

Stage 1 of nervous system development

Neurogenesis/generation of new neurons by mitosis at the ventricular zone of the neural tube. Begins very early.

Stage 2 of nervous system development

Cell migration to the appropriate locations in the developing brain thanks to radial glial cells which guides for them to move.

Stage 3 of nervous system development

Differentiation into particular neurons types controlled by gene expression, certain neurons will express certain genes (turning other genes off) and axons/dendrites establish synaptic connections

Stage 4 of nervous system development

Synaptogenesis (formation of functional connections between neurons) between the 3rd trimester and 2 years of age. There’s a growth cone they respond to chemical signals from target cells — which tells them where to go, and where to make the connections. Target cells release chemo attractant and chemo repellent molecules (make sure synaptic repellents are in proper location)

Stage 5 of nervous system development

Neural cell death. Apoptosis (naturally occurring cell death). Neurons successfully compete for neurotrophic factions will survive, those that don’t will die.

Stage 6 of nervous system development

Synaptic rearrangement. A fine tune system to redefine synaptic connections and go to appropriate locations.

Spina bifida

Occurs when the neural tube fails to close at the causal end causing a malfunction of the spinal cord at the posterior end

Anencephaly

brain fails to adequately develop which is not compatible with life.

Genotype sex

xx vs xy

Phenotype sex

Sexual characteristics we express in the structure of the body and also the brain

Genotypic / genetic sex

Determined at the time of conception and depends whether the sperm that fertilizes the egg is carrying an x or y chromosome

6 weeks of gestation

Fetus has undifferentiated gonads —> sex chromosomes are going to determine whether they develop into tested or ovaries

SRY gene

Produced protein that causes gonads to develop into testes

Hypothalamus

Courtship behaviors, mating later in life

Congenital adrenal hyperplasia - CAH

Adrenal glands of the fetus produce abnormally high amounts of androgen hormones (male sex hormones) — xx female —> partial masculinization

Androgen insensitivity syndrome - AIS

Male tested producing testosterone but their androgen receptors are dysfunctional— genetic mutation (not responding)

Affects genotypic xy male

What is epigenetics

Functionally relevant modifications to the DNA that do not involve a change in the nucleotide of the gene themselves.

DNA methylation

Methyl groups directly onto the DNA itself which often results in gene silencing

Histone modification

When certain enzymes bind to those histone tails it can result in either tightening or loosening of the DNA

High licking and grooming mothers (epigenetic effects)

Offspring show higher density of glucocorticoid receptors in hippocampus, more resilient to stress

Low licking and grooming (epigenetic effects)

Fewer glucocorticoid receptors, increase stress response

Nutrition and epigenome

(Study on Mice)

2 mice are identical and have exactly the same genes.

If a mice mother is exposed to BPA in utero (chemical found in polycarbonate plastic) their offspring will be obese and prone to health issues like diabetes and cancer

If a mice mother is given methyl rich diet like choline, folic acid, betaine and vitamin B 12. Offspring will be leaner, healthier and have lower disease risk.

Epigenetic differences - Monozygotic twins

Gene expression in very young identical twins are much more similar gen even expression patterns in older identical twins.

As twins age, even if the DNA sequence of their genes remains the same, the expression of those genes starts to diverge or become very different over time.