ABSTRACT
The process of ectopic bone formation suggests that extraskeletal cells are capable of osteogenesis. Alkaline phosphatase (ALP) activity is considered to be an early marker of osteogenic differentiation. This study determined whether cells from the rabbit dermis, striated muscle and extramedullary adipose tissue could undergo osteogenic differentiation in vitro. The cells were cultured with two osteoregulators, recombinant human bone morphogenetic protein 2 (rhBMP2) and dexamethasone. Incubation of extramedullary adipose cells with a combination of rhBMP2 and dexamethasone resulted in an increase in their ALP activity. The results suggest that extramedullary adipocytic cells may undergo osteogenic differentiation.
Subject(s)
Adipose Tissue/cytology , Bone Marrow Cells , Mesoderm/cytology , Muscle, Skeletal/cytology , Osteogenesis/drug effects , Skin/cytology , Adipose Tissue/drug effects , Adipose Tissue/enzymology , Alkaline Phosphatase/metabolism , Animals , Bone Marrow/drug effects , Bone Marrow/enzymology , Bone Morphogenetic Protein 2 , Bone Morphogenetic Proteins/pharmacology , Cell Differentiation/drug effects , Cell Differentiation/physiology , Cells, Cultured , Dexamethasone/pharmacology , Glucocorticoids/pharmacology , Humans , Muscle, Skeletal/drug effects , Muscle, Skeletal/enzymology , Osteoblasts/cytology , Osteoblasts/drug effects , Osteogenesis/physiology , Rabbits , Recombinant Proteins , Skin/drug effects , Skin/enzymology , Transforming Growth Factor beta/pharmacologyABSTRACT
Rhizobium meliloti is known to use betaines synthesized by its host, Medicago sativa, as osmoprotectants and sources of energy. It is shown in the present report that the symbiotic megaplasmid (pSym) of R. meliloti RCR2011 encodes functions essential to the catabolism of three betaines, trigonelline (nicotinic acid N-methylbetaine), stachydrine (proline betaine or dimethylproline), and carnitine (gamma-trimethyl-beta-hydroxybutyrobetaine). Preliminary evidence is presented showing that functions on pSym also influence the catabolism of choline and its oxidative product, glycine betaine. Genes implicated in betaine catabolism are found in the symbiotic region of pSym. Trigonelline catabolism functions lie between two clusters of symbiotic genes, nifKDH and nok/fixVI'. Stachydrine and carnitine functions lie to the right of trigonelline catabolism functions, immediately to the right of fixVI'. Information necessary to choline and glycine betaine catabolism is probably encoded to the right of stachydrine catabolism functions.
