Hematopoiesis - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 35

Tabl e 2. 6. Factors of self-renewal of hematopoietic stem cells (Source: [ 69 ]; BMI1: murine
leukemia viral [BMI1] Polycomb RING finger proto-oncogene product, or RING finger protein
RNF51; BMP: bone morphogenetic protein; CBP: CREB-binding protein; Cdx: caudal type home-
obox gene product; CKI: cyclin-dependent kinase inhibitor; ETV: ETS variant; EZH: enhancer of
zeste homolog [Polycomb group; (histone) lysine N-methyltransferase]; GATA: DNA sequence
GATA-binding protein; GFI1: growth factor independent-1 transcription repressor, or zinc finger
protein ZnF163; Hox: homeobox gene product; MEIS: myeloid ecotropic viral integration site
homeobox protein; MLL: myeloid-lymphoid or mixed-lineage leukemia proto-oncogene product
[a.k.a. histone-lysine N-methyltransferase KMT2a, HRX, and trithorax homolog]; MyB: Myb
myeloblastosis viral proto-oncogene homolog; MyC: Myc myelocytomatosis viral proto-oncogene
homolog; PHc1: polyhomeotic homolog-1 [a.k.a. early development regulatory protein EDR1,
polyhomeotic-like protein PH1, homolog of polyhomeotic HPc1, and RAE28; homeotic genes
are involved in developmental patterns]; Sox: SRY (sex-determining region Y)-box; SPI1: spleen
focus-forming virus [SFFV] proviral integration proto-oncogene product [or transcription factor
PU.1]; ZFX: X-linked zinc finger protein, or ZnF926).

Category Types

Hox transcription factors HoxA7/9/10, HoxB4, CdX2/4, MEIS1

Growth factors Notch, Wnt, BMP

Modulators Angiopoietin-like factors, thrombopoietin,

stem cell factor, retinoic acid,
prostaglandin-E2

Transcription factors CBP, ETV6, GATA2, GFI1, MyB,

SPI1, Sox17, ZFX

Cell cycle regulators CKI1a/b-CKI2a/c, MyC, P53, PTen

Chromatin-associated factors EZH2, BMI1, MLL, PHc1

structures, such as vertebrae and limbs, in humans. Distinct Hox proteins operate in
different tissues, with distinct functions, targeting different sets of genes. 27
Expression of HOX genes is regulated by members of caudal-type (CDX),
preB-cell leukemia homeobox (PBX), and myeloid ecotropic viral integration site
(MEIS) families of Hox cofactors [ 69 ]. Moreover, expression of HOX genes is
modulated by growth factors and morphogens, such as Hedgehog, Notch, bone
morphogenetic proteins, and Wnt (Vol. 3 - Chaps. 8. Receptor Kinases and 10.
Morphogen Receptors).

Chromatin Remodelers of the Polycomb Group for Epigenetic Silencing

Polycomb group proteins participate in 2 polycomb repressive complexes PRC1 and
PRC2 that regulate HSC self-renewal. In addition, some substances (e.g., retinoic
acid and prostaglandin-E2) modulate HSC self-renewal.

27 HOX genes are clustered on some chromosomes. In humans, 4 clusters exist (39 HOX genes
each [ 68 ]): HOXA cluster in chromosome 7; HOXB cluster in chromosome 17; HOXC cluster in
chromosome 12; and HOXD cluster in chromosome 2.