1. Hematopoietic stem cell
HEMATOPOIESIS
Hematopoietic stem cell

2. Hematopoietic Homeostasis Involves Many Factors
Steady-state regulation of hematopoiesis is accomplished
in various ways, which include:
Control of the levels and types of cytokines produced by bone-marrow stromal cells
The production of cytokines with hematopoietic activity by other cell types, such as activated T cells and macrophages
The regulation of the expression of receptors for hematopoietically active cytokines in stem cells and progenitor cells
The removal of some cells by the controlled induction of cell death

3. Some transcription factors essential for hematopoietic lineages
Dependent lineage
GATA-1
Erythroid
GATA-2
Erythroid, myeloid, lymphoid
PU.1
Erythroid (maturational stages), myeloid (later stages), lymphoid
BM11
Myeloid, lymphoid
Ikaros
Lymphoid
Oct-2
B lymphoid (differentiation of B cells into plasma cells)

4. Programmed Cell Death Is an EssentialHomeostatic Mechanism
Cells undergoing programmed cell death often exhibit distinctive morphologic changes, collectively referred to as apoptosis. Does not induce inflammatory response.
Apoptosis differs markedly from necrosis, the changes associated with cell death arising from injury. Induce local inflammatory response.

5. Genes that regulate apoptosis
Function
Role in apoptosis
bcl-2
Prevents apoptosis
inhibits
bax
Opposes bcl-2
promotes
bcl-Xl
Prevent apoptosis
inhibit
bcl-Xs
Oppose bcl-Xl
Caspases
protease
fas
Induce apoptosis
initiates