Growth and differentiation

In summary, heparan sulfate PG localizes a number of different growth factors at the cell surface or in the extracellular matrix and promotes their activities of cell growth and differentiation. 

In the first adhesion step of the leukocytes extravasation process, selectins (including L-selectin, E-selectin, and P-selectin), along with heparan sulfate PGs, 

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Aon M A and Cortassa S 1995 Cell growth and differentiation from the perspeotive of dynamioal organization of oellular and suboellular prooesses Prog. Biophys. Molec. Biol. 64 55-79... 

Figure 13.24 Six subfamilies of receptor tyrosine kinases involved in cell growth and differentiation. Only one or two members of each subfamily are indicated. Note that the tyrosine kinase domain is interrupted by a "kinase insert region" in some of the subfamilies. The functional significance of the cysteine-rich and immunoglobulin-like domains is unknown.

PKC isozymes are involved in a wide array of diverse cellular functions [5]. Most isozymes (e.g., PKC (3) are involved in proliferative responses, and hyperactivation with phorbol esters most typically results in cell growth and differentiation. However, isozymes can have opposing functions. PKC 8 is well-characterized as an apoptotic kinase, whereas the closely related PKC e is antiapoptotic. PKC also plays a key role in learning and memory. 

Vitamin A (retinol) and its naturally occurring and synthetic derivatives, collectively referred to as retinoids (chemical structure), exert a wide variety of profound effects in apoptosis, embryogenesis, reproduction, vision, and regulation of inflammation, growth, and differentiation of normal and neoplastic cells in vertebrates. 

Other small monomeric GTPases (eg, ARF, Rab, Ras, and Rho) are important in various cellular processes such as vesicle formation and transport (ARF and Rab see below), cettain growth and differentiation processes (Ras), and formation of the actin cytoskele-ton. A process involving GTP and GDP is also crucial in the ttanspott of ptoteins across the membrane of the ER (see below). 

In attempting to quickly elucidate the possible mechanisms of action of a toxin, there are a number of obvious routes to take. In the case of a toxin which has a rapid and acute lethal action, the route is especially obvious, but with toxins having effects on growth and differentiation, the best approach is more obscure. 

This may oeeur by the production of cytokines with inhibitory funetion the ability to absorb neeessary growth and differentiation faetors the possible lysis of eells bearing the stimulatory antigens in assoeiation with MHC moleeules (Class I and Class II) the possible release of speeifie soluble factors (TsF) which may be direeted at either the TH eell or the B eell. 

Whether or not the production of /1-amyloid can be curtailed, it would be desirable to either replace the damaged neurons or encourage the remaining functional ones to ramify further and exhibit more influence. The former, which requires tissue or cell line grafts, is currently not feasible and barely investigated experimentally but there is much interest in the possible use of neurotrophic proteins (neurotrophins) that encourage neuronal growth and differentiation. 

GAMET L, DAViAUD D, DENis-POUXViEL 0, REMESY 0, MURAT J 0 (1992) Effects of shoit-chain fatty acids on growth and differentiation of the human colon-cancer cell line HT29. Int J Cancer. 52 286-9. 

IL-6 T lymphocytes, monocytes, macrophages, synovial fibroblasts Activates T lymphocytes, induces acute-phase response, stimulates growth and differentiation of hematopoietic precursor cells stimulates synovial fibroblasts... 

Monod J, Jacob F. General conclusions teleonimic mechanisms in cellular metabolism, growth and differentiation. Cold Spring Harbor Symp Quant Biol 1961 26 389-401. 

Besmer, P. (1991). The kit ligand encoded at the murine Steel locus a pleiotropic growth and differentiation factor. Curr. Opin. Cell Biol. 3 939-946. 

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