Incorporation of radiolabelled alphafetoprotein in the brain and other tissues of the developing rat

Villacampa, M.J.; Lampreave, Fermı́n; Calvo, Miguel; Naval, Javier; Piñeiro, Andrés; Uriel, J

doi:10.1016/0165-3806(84)90177-9

Cited by 40 publications

(21 citation statements)

References 14 publications

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“…We have shown that fetuin could be internalized by the cultured human VSMCs and secreted from these cells when surrounded by a medium deficient in fetuin. Our data are consistent with the presence of a receptor-mediated uptake mechanism, a mechanism shown to exist in embryonic and proliferating cells, but not in resting differentiated cells (32). Serum fetuin carries calcium phosphate (41) and has been shown to play a major role in preventing calcium phosphate precipitation from serum and deposition of the salt in extrahepatic tissues (42).…”

Section: Discussionsupporting

confidence: 75%

Processing and Transport of Matrix γ-Carboxyglutamic Acid Protein and Bone Morphogenetic Protein-2 in Cultured Human Vascular Smooth Muscle Cells

Wajih¹,

Borrás

Wang

et al. 2004

Journal of Biological Chemistry

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Matrix ␥-carboxyglutamic acid protein (MGP) is a member of the vitamin K-dependent protein family with unique structural and physical properties. MGP has been shown to be an inhibitor of arterial wall and cartilage calcification. One inhibitory mechanism is thought to be binding of bone morphogenetic protein-2. Binding has been shown to be dependent upon the vitamin K-dependent ␥-carboxylation modification of MGP. Since MGP is an insoluble matrix protein, this work has focused on intracellular processing and transport of MGP to become an extracellular binding protein for bone morphogenetic protein-2. Human vascular smooth muscle cells (VSMCs) were infected with an adenovirus carrying the MGP construct, which produced non-␥-carboxylated MGP and fully ␥-carboxylated MGP. Both forms of MGP were found in the cytosolic and microsomal fractions obtained from the cells by differential centrifugation. The crude microsomal fraction was shown to contain an additional, more acidic Ser-phosphorylated form of MGP believed to be the product of Golgi casein kinase. The data suggest that phosphorylation of MGP dictates different transport routes for MGP in VSMCs. A proteomic approach failed to identify a larger soluble precursor of MGP or an intracellular carrier protein for MGP. Evidence is presented for a receptormediated uptake mechanism for fetuin by cultured human VSMCs. Fetuin, shown by mass spectrometry not to contain MGP, was found to be recognized by anti-MGP antibodies. Fetuin uptake and secretion by proliferating and differentiating cells at sites of calcification in the arterial wall may represent an additional protective mechanism against arterial calcification.

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Section: Discussionsupporting

confidence: 75%

Processing and Transport of Matrix γ-Carboxyglutamic Acid Protein and Bone Morphogenetic Protein-2 in Cultured Human Vascular Smooth Muscle Cells

Wajih¹,

Borrás

Wang

et al. 2004

Journal of Biological Chemistry

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“…After migrating to their definite locali zation, they aggregate to form the presump tive ganglion [11], The origin of neural AFP remains debated. Recent in vivo work in mammals and avians suggests the exogenous origin of intracellular AFP in the CNS [12][13][14] while other reports conclude that the protein may be synthetized in situ [15], We present here evidence that organotyp ic cultures of sensory dorsal root ganglia can incorporate exogenous purified AFP (and SA) under suitable experimental conditions. In the case of AFP, this incorporation is asso ciated with a certain degree of cell and tissue differentiation; we did not find a similar rela tion for SA.…”

Section: Introductionmentioning

confidence: 67%

In vitro Uptake of Exogenous α-Fetoprotein by Chicken Dorsal Root Ganglia

et al. 1983

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Exogenous chicken α-Fetoprotein (AFP) was added to embryonic chick dorsal root ganglia plated on gelatin-coated tissue culture dishes at different stages during the differentiation process and its intracellular uptake demonstrated by immunocytochemical methods. Other embryonic serum proteins were added as a control. Morphologically well-differentiated neurons (ganglion cells) appeared positively labeled for AFP, contrasting with weakly stained other cell types: these included spindle-shaped cells identified as Schwann cells and larger, often closely packed cells, which could be less mature neurons. Fibroblasts were found negative or faintly stained. No AFP was noticeable in cultures grown in the absence of the protein. These results suggest that the presence of AFP in the developing CNS is for the most part, if not entirely, due to protein uptake as opposed to in situ synthesis.

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“…Several in vitro and in vivo (Villacampa et al, 1983;Pineiro et al, 1982;Moro et al, 1984) studies support the conclusion that the presence of AFP, and perhaps of SA, results from protein uptake as opposed to eventual in situ synthesis (Ali et al, 1983). The ability to incorporate AFP, common to many tissues during ontogenesis may reappear in neoplastic cells 1984a).…”

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confidence: 63%