Expression and distribution of fetuin in the developing sheep fetus

Abstract

Tissue distribution and developmental expression of fetuin were studied in the sheep fetus from embryonic day (E) 30 to adult (gestational period is 150 days). The presence of fetuin was demonstrated immunocytochemically using anti-fetuin antibodies; in situ hybridisation using short anti-sense oligonucleotide probes labelled with digoxigenin was used to study the ability of the developing tissue to synthesise fetuin, and reverse transcription-polymerase chain reaction (RT-PCR) was used to estimate the level of fetuin mRNA in selected tissues. Tissue distribution of fetuin was widespread in the younger fetuses (E30 to E40). The most prominent presence due to in situ synthesis was demonstrated in the liver, central nervous system (CNS) including anterior horn cells, dorsal root ganglia and in skeletal muscle cells. Other developing tissues and organs that showed evidence of fetuin synthesis and presence of the protein included mesenchyme, kidney, adrenal, developing bone, gut, lung and heart. In the immature liver (E30-40) there was a strong signal for fetuin mRNA in hepatocytes and also in numerous haemopoietic cells; the proportion of these latter cells that was positive for fetuin mRNA increased between E30 and E40. Only some hepatocytes and a proportion of the haemopoietic stem cells were immunoreactive for fetuin itself at E30-40; immunoreactive hepatocytes were more frequently observed in the more mature outer regions of the developing liver. Lung and gut contained scattered fetuin-positive epithelial cells, especially at E30; a weak fetuin mRNA signal could be detected above background in many of these cells up to E40, but not at E60-E115 or in the adult. Particularly at E30 to E40, mesenchymal tissue both within organs such as the gut and lung and around forming bone and skeletal muscle contained cells that were positive for fetuin mRNA. Mesenchyme at these ages was also very strongly stained for fetuin protein, much of which may reflect fetuin in tissue extracellular spaces and be derived from the high concentration in plasma. By E80 fetuin mRNA was mainly present in the liver and the CNS; staining of the muscle tissue was becoming less pronounced. However in developing bone tissue, staining of chondrocytes for fetuin mRNA was still prominent in older (E80) fetuses; there was also fetuin protein staining of chondrocytes at the growing surfaces of bones and in bone marrow at this age. In the adult, weak immunocytochemical staining for fetuin itself was present in hepatocytes, but the mRNA signal was barely above the threshold limit of detection.(ABSTRACT TRUNCATED AT 400 WORDS)

Cloning and Targeted Deletion of the Mouse Fetuin Gene

“…Fig. 7 illustrates the results of a typical experiment in which spontaneous apatite formation from supersaturated solutions of CaCl 2 and Na 2 HPO 4 was measured as incorporation of 45 Ca into the insoluble salt pellet. The precipitation reactions proceeded for 30 min at 37°C either in the absence of serum (control) or in the presence of 10% dialyzed serum from wildtype Ahsg ϩ/ϩ , heterozygous Ahsg ϩ/Ϫ , or homozygous Ahsg…”

“…Inhibition of Apatite Formation-To estimate the inhibition of salt precipitation by serum, assays were done in 20 mM Tris, pH 7.4, 100 mM NaCl, 1.6 mM Na 2 HPO 4 , and 4.8 mM CaCl 2 containing a trace amount of 45 CaCl 2 . Sera were dialyzed by repeated spin dialysis against incubation buffer using Microcon 10 centrifuge concentrators (Amicon, Inc.).…”

cDNA Sequencing of Guinea Pig a2-HS Glycoprotein, Its Expression in Various Tissues and Acute Phase Expression

“…In the adult mouse, AHSG mRNA was detected mainly in the liver and also in the adrenal gland, stomach, heart and placenta by Northern blot analysis (Yang et al, 1992). In the adult sheep fetuin was detected in the liver, spleen, lymph node, skeletal muscle and bone marrow by immunocytochemistry but not in the central nervous system, kidney, heart and lung (Dziegielewska et al, 1996;Saunders et al, 1994). In the newborn rat, fetuin was observed in the liver, pancreas, cerebral cortex, blood vessels, cartilage and bone, smooth muscle, spleen, bone marrow and kidney by immunocytochemistry but not in the lung and adrenal gland (Terkelsen et al, 1998).…”

Molecular Characterization and Expression Pattern of Fetuin-B in Gibel Carp (Carassius auratus gibelio)

“…In mouse embryo, fetuin-A transcript could also be detected in a number of developing tissues and organs other than hepatic tissue, such as heart, lung, kidney, nervous system, and limb buds during the particular stages (Yang et al 1992). In fetal neonatal rats and fetal sheep, the presence of fetuin-A mRNA was also found in many of the germinal cell populations of developing tissues and organs including brain, kidney, haemopoietic liver, early gastrointestinal epithelium, bone, and muscle (Saunders et al 1994;Terkelsen et al 1998), and its protein was predominantly in the developing central and peripheral nervous system, cerebrospinal fluid, and plasma (Kitchener et al 1999;Dziegielewska et al 2000). It has been demonstrated that fetuin-A plays important roles during developmental processes, including osteogenesis, myotubule (Yang et al 1992), fetal brain, and nervous system development (Kitchener et al 1999;Dziegielewska et al 2000).…”

“…Fetuin-A was first identified in fetal cow in 1944 (Pedersen 1944). In recent years, fetuin-A homologs have been cloned in sheep, pigs, cows, humans, mice, gerbils, and rats (Auberger et al 1989;Rauth et al 1992;Saunders et al 1994;Goto et al 1997;Brown and Dziegielewska 1997). Fetuin-A has been shown to function in many physiological aspects, such as fatty acid transport (Cayatte et al 1990), regulation of insulin activity and hepatocyte-growth-factor activity (Mathews et al 2002;Ohnishi et al 1997), response to systemic inflammation (Ombrellino et al 2001), and inhibition of unwanted mineralization (Schinke et al 1996;Heiss et al 2003;Schäfer et al 2003).…”