Tissue Development, Repair, and Remodeling - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 678

Table 11.3. Features of transcription factors and microRNAs (Source: [ 1391 ]).

Transcription factors MicroRNAs

Pleiotropy + +

Cooperation Cooperative binding to Cooperative activity

cognate DNA sequences
Cooperative recruitment
of transcription cofactors

Recognition of Nucleosome coating RNA-binding proteins;

site accessibility folding of target

and binding mRNA sequences;

other microRNAs

Regulation Activation or Repression mostly;

repression; fast, reversible repression;

slower activity quick reactivation

( ± translocation)

Expression MicroRNA dependency; Post-translational

feedback; regulated maturation;

post-translational RNA editing

regulation (adenosine-to-inosine conversion);

(phosphorylation) microrna cofactor modifications

circulation then carries these gases inside the cardiovascular system that irrigates
and drains body tissues. The 2 serial ventilatory and circulatory networks transport
oxygen to cells and remove carbon dioxide from them.

11.3.1 Airway Morphogenesis

In mammals, air enters the organism through the nasal and oral cavities and crosses
the pharynx, larynx, and trachea. The trachea branches into 2 stem bronchi that give
rise to densely branched left and right bronchial trees inside lung parenchymas.
The bronchial tree of the human lung contains more than 105 conducting and
107 respiratory airways [ 1392 ].
During mammalian embryogenesis, lungs develop from 2 primary buds that
arise in the ventral foregut. These buds undergo extensive branching under the
reciprocal control of the epithelial endoderm and surrounding mesoderm. Terminal
buds may contain a population of multipotent epithelial progenitors [ 1393 ]. As
airways extend, descendants of these cells give rise to progenitors of the major
cell types of airways, such as ciliated and secretory Clara cells. Differentiation of
epithelial cells begins proximally and proceeds distally. Once airway morphogenesis
is complete, the lung continues to increase in size and new epithelial cells are