Characterization of common salivary protein 1, a product of rat submandibular, sublingual, and parotid glands.

We have isolated and characterized cDNA clones derived from a developmentally regulated neonatal rat submandibular gland salivary protein gene called "common salivary protein 1" (CSP1). Identical clones were also identified in cDNA libraries from adult male parotid, submandibular, and sublingual glands. CSP1 transcripts are at least 10-fold more abundant in the sublingual gland than in the submandibular or parotid glands. In situ hybridization and immunocytochemical localization demonstrated the presence of CSP1 transcripts and proteins in sublingual gland serous demilune cells, parotid and submandibular gland intercalated duct cells, and in the type III (proacinar) cells of the neonatal submandibular gland. This cell-type distribution is similar to that described by Ball and colleagues (Ball, W. D., Hand, A. R., and Johnson, A. O. (1988) Dev. Biol. 125, 265-279) for the developmentally regulated submandibular gland B1-immunoreactive proteins. Immunoblotting of salivary secretion identified proteins of M(r) 20,000 in sublingual, 16,000 in submandibular and 22,000 and 16,000 in parotid gland. The M(r) 20,000 sublingual and 22,000 parotid proteins represent N-glycosylated forms of a M(r) 16,000 apoprotein, suggesting that these salivary proteins arise by post-translational modification of a common precursor.

Molecular cloning of developmentally regulated neonatal rat submandibular gland proteins.

At birth, the rat submandibular gland (SMG) contains two transient secretory cell types that produce several characteristic salivary proteins. Proteins SMG-A, B1, and B2 (23.5, 26 and 27.5 kDa) are products of the neonatal type III cells, but not the adult acinar cells. Protein C (89 kDa), a major product of the neonatal type I cells, is either absent or present at greatly diminished levels in the secretory cells of the adult gland. The decrease in biosynthesis of these neonatal salivary proteins occurs concomitantly with the increase in levels of characteristic adult SMG products. In order to understand these developmentally regulated changes in SMG salivary protein gene expression, we have initiated the molecular cloning and characterization of neonatal submandibular gland proteins from a 5-d-old rat submandibular gland cDNA library. Clones encoding SMG-A were isolated by homology to the mouse parotid secretory protein (PSP). SMG-A was shown to be derived from a salivary protein multigene family that also includes PSP. Cloning and characterization of additional neonatal rat submandibular gland proteins was initiated by screening the 5-d-old rat submandibular gland cDNA library with first strand cDNA prepared from 1-d-old rat submandibular glands. Clones corresponding to a highly abundant 3 kb transcript present in the neonatal rat SMG, but not in adult submandibular, sublingual, or parotid gland have been identified. The size, abundance, and organ specificity of this transcript suggest that it may encode protein C.(ABSTRACT TRUNCATED AT 250 WORDS)

Behavior of mouse placental and uterine estrogen sulfotransferase during chromatography and other procedures.

The estrogen sulfotransferase activity of high-speed supernatants of mouse placenta and uterus behaves on conventional and high-performance liquid chromatographic gel filtration as an enzyme species with a molecular weight of the order of 30 000. This is so whether the cytosols are freshly prepared or have been stored at -20 degrees C before chromatography. The presence of thiol groups or EDTA has no effect on the elution pattern. The partially purified enzyme is extremely unstable and is poorly recovered by (NH4)2SO4 fractionation. Some stabilization can be achieved in the presence of 0.1 microM estradiol. Chromatofocusing of cytosols results in the elution of one or two sulfotransferase peaks, depending upon experimental conditions such as the presence or absence of thiol groups. These peaks act upon both estrone and estradiol as substrates. Chromatofocusing by fast protein liquid chromatography (FPLC) in the absence of thiol groups results in the elution of one sulfotransferase peak whose activity can be detected only when thiol groups are present during enzyme assay.

Development and characteristics of an oestrogen sulphotransferase in placenta and uterus of the pregnant mouse. Comparison between mouse and rat.

The mouse placenta possesses a soluble oestrogen sulphotransferase activity which increases markedly from at least 12 days of gestation until term. At about 16 days of gestation, a similar activity is found in the uterus. This activity also increases until term and disappears rapidly post partum. The uterine enzyme activity appears to require the presence of the foetal unit for its onset, since unoccupied horns, whether their endometrial stromal cells are differentiated to decidual cells or not, are essentially devoid of it. Uterine cytosols from non-pregnant mice are also inactive in this respect. In late gestation, the uterine sulphotransferase is confined to the decidua basalis, the areas to which the placentas are attached. The sulphotransferase(s) of placenta and uterus has an absolute requirement for 3'-phosphoadenosine 5'-phosphosulphate, and possesses little activity in the absence of exogenous thiol groups. Stimulation is also seen in the presence of Mn2+, Mg2+ or Ca2+. Oestrone and oestradiol, and to a lesser degree oestriol, are substrates for the enzyme(s), whereas testosterone, cortisol and dehydroepiandrosterone are not. Oestrone and oestradiol at higher concentrations (1.0-1.5 microM) completely inhibit the enzyme(s). These enzymes could play a role in altering tissue concentrations of active oestrogens during gestation in the mouse. Oestrogen sulphotransferase activity is low or absent in reproductive tissues of the pregnant rat.