A family of POU-domain and Pit-1 tissue-specific transcription factors in pituitary and neuroendocrine development

The anterior pituitary gland provides a model for investigating the molecular basis for the appearance of phenotypically distinct cell types, within an organ, a central question in development. The rat prolactin and growth hormone genes are selectively expressed in distinct cell types (lactotrophs and somatotrophs) of the anterior pituitary gland, which reflect differential mechanisms of gene activation or restriction because of interactions of multiple factors binding to these genes. We find that the pituitary-specific 33,000 dalton transcription factor, Pit-1, normally expressed in somatotrophs, lactotrophs, and thyrotrophs, can bind to and activate both growth hormone and prolactin promoters in vitro at levels even tenfold lower than those normally present in pituitary cells. In the case of the prolactin gene, high levels of expression in transgenic animals required two cis-active regions; a distal enhancer (-1.8 to -1.5 kb) and a proximal region (-422 to +33 bp). Each of these regions alone can direct low levels of fusion gene expression to prolactin-producing cell types in transgenic mice, but a synergistic interaction between these regions is necessary for high levels of expression. The initial appearance of the prolactin transgene expression closely follows the appearance of high levels of Pit-1, but later increases in expression coincident with appearance of mature lactotrophs suggest the operation of additional, critical positive factor(s). Unexpectedly, transgenes containing the distal enhancer removed from its normal context are expressed in both the prolactin-producing lactotrophs and the TSH-producing thyrotrophs, thereby suggesting that sequences flanking this enhancer are necessary to restrict expression to the correct cell type within the pituitary. These data indicate that distinct processes of gene activation and restriction are necessary for the fidelity of cell-type specific expression within an organ. Consistent with this model, we find that lactotroph cell lines that cannot express the growth hormone gene contain high levels of functional Pit-1. We suggest a large, highly related POU-domain gene family, potentially exceeding 100 members, has been conserved and expanded in evolution to meet the increasing requirements for more intricate patterns of cell phenotypes. The POU-domain subgroup of the homeodomain gene family, in concert with other homeodomain proteins and with other classes of transcription factors, is likely to contribute to the establishment of the mammalian neuroendocrine system.

[Determination of tangshenoside I in Codonopsis pilosula Nannf. by TLC-UV spectrophotometric method]

A method of thin layer chromatographic separation and ultraviolet spectrophotometric determination of tangshenoside I in Codonopsis pilosula is described. A comparison of the contents in various samples is made. The contents of tangshenoside I in frosted sample have been found to be twice as much as in normal drug. The recovery of tangshenoside I is 99.92% and the coefficient of variation of eight samplings is 1.77%.

Circulating glycoconjugates in CSF of meningioma patients

This study investigated whether tumor-associated gangliosides or glycoproteins may be markers for meningiomas in CSF. The concentrations of a number of gangliosides and sulphatide were determined with specific monoclonal antibodies and cholera toxin B-subunit in a thin-layer chromatography overlay technique. As compared to a reference group of 10 individuals (mean age 50 +/- 14 years), the CSF samples from 7 meningioma patients (mean age 55 +/- 12 years) were found to contain significantly increased concentrations of ganglioside GD3 [II3(NeuAc)2-LacCer], one of the major gangliosides in meningioma tissue specimens. Sulphatide was significantly increased in 6 of 7 patients. Tumor-associated glycoproteins detected by the lectin Ricinus communis 1 in meningioma tissue specimens, but not in normal human brain tissue, were also found in the CSF of the meningioma patients. An early diagnosis of meningiomas might be achieved by the combined assay in CSF of ganglioside GD3 and glycoproteins with Ricinus communis lectin.

Synthesis and resolution of novel 3'-substituted phenylalanine amides

A convenient approach to the synthesis of ring-substituted phenylalanine amides is described. Phase transfer alkylation of N-(diphenylmethylene)amino acetonitrile or N-(diphenylmethylene)glycine ethyl ester provides alpha-substituted imines 2 and 6. After acid hydrolysis and esterification, resolution with alpha-chymotrypsin provided 3'-substituted phenylalanine analogs 9a-d which could easily be converted to N alpha-t-butyloxycarbonyl-phenylalanine amides for use in the synthesis of peptide analogs. The approach described here is amenable to the synthesis of 3-substituted phenylalanines with a wide variety of substituents for determination of structure-activity relationships of peptides.

[Chemical constituents of Codonopsis pilosula Nannf]

An exclusive constituent has been isolated from the water soluble parts of root of Codonopsis pilosula for the first time. The constituent has been confirmed to be tangshenosid I.

GD3 expression by cultured human tumor cells of neuroectodermal origin

Seven monoclonal antibodies (mAbs) reactive with ganglioside II3(NeuAc)2-LacCer (GD3) were generated; four of these mAbs (DMAb-21, DMAb-22, DMAb-23, and DMAb-24) by immunizing mice with GD3 adsorbed to Salmonella minnesota and the remaining three (DMAb-7, DMAb-8, and DMAb-17) with melanoma line SK-MEL 28, which contains 1.4 nmol sialic acid of GD3 per mg protein. The specificities of the mAbs were defined by high-performance thin-layer chromatography (HPTLC) immunostain and solid-phase radioimmunoassay (SP-RIA) with a panel of purified gangliosides. DMAb-7 and DMAb-8 reacted with GD3, IV3(NeuAc)2nLcOse4Cer(3',8'-LD1), and very weakly with IV3(NeuAc)2II3NeuAcGgOse4Cer (GT1a), but not with II3NeuAc-LacCer (GM3), II3NeuAcGgOse3Cer(GM2), II3NeuAcGgOse4Cer (GM1), II3NeuAc, IV3NeuAcGgOse4Cer (GD1a), II3(NeuAc)2GgOse3(GD2), II3(NeuAc)2GgOse4Cer (GD1b), IV3NeuAcII3(NeuAc)2, GgOse4Cer(GT1b), suggesting the binding epitope to be a terminal tetrasaccharide NeuAc alpha 2-8NeuAc alpha 2-3Gal beta 1-4(Glc or GlcNAc). DMAb-7 and DMAb-8 were used to investigate the expression of GD3 on cultured human tumor cells of neuroectodermal origin. Thirteen of 19 gliomas, 3 of 5 medulloblastomas, 5 of 5 neuroblastomas, 2 of 2 melanomas, and 1 of 3 teratomas were shown to react with DMAb-8 and/or DMAb-7 by cell surface-RIA (CS-RIA) and immunofluorescence (IF) assays. HPTLC and densitometric analysis confirmed these results, as positive immunostains in the GD3 region were obtained with oligoganglioside fractions from 9 glioma, 1 medulloblastoma, 2 neuroblastoma, 1 melanoma, and 1 teratoma cell line. Glioma cell line U-105 MG and medulloblastoma cell line Daoy contain GD3 as shown by HPTLC immunostain analysis of extracts, although GD3 was undetectable on the cell surface as determined by CS-RIA and IF.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of a large family of POU-domain regulatory genes in mammalian brain development

A novel region referred to as the POU-domain is present in two tissue-specific transcription factors, Pit-1 and Oct-2, that activate expression of genes specifying pituitary and lymphocyte phenotypes. We report the identification of multiple new members of a large family of POU-domain genes expressed in adult brain, and document that all the known mammalian POU-domain genes, including Pit-1 and Oct-2, are expressed widely in the developing nervous system.

Effects of capsaicin on articular afferents of the cat's knee joint

This study on the effects of capsaicin on primary afferents from normal knee joints of the cat was performed to further elucidate the mechanisms of articular pain evoked by an acute arthritis and by chemical irritants. It showed that close i.a. bolus injection of capsaicin (10(-7)-10(-4) M) excites most fine articular afferents (conduction velocity less than or equal to 11.3 m/s) whereas fast units are not excited. Fine afferents with low to medium thresholds to knee joint movement are less readily excited by capsaicin than high threshold ones. The response to capsaicin is usually a rapid burst of impulses of a very short latency. This response pattern differs considerably from that seen after application of endogenous substances produced in inflammation. Thus capsaicin seems to differ in its mode of action from that of endogenous algesic substances.

Steroid receptor-mediated inhibition of rat prolactin gene expression does not require the receptor DNA-binding domain

Prolactin gene expression is negatively regulated by glucocorticoids, and by estrogens when positive estrogen regulatory elements in the prolactin gene are removed. Mutational analysis of estrogen receptor confirms that inhibition is a function of receptor, and that transcriptional activation and inhibition require distinct, separable structural elements. Inhibition is dependent on a 63 amino acid region (amino acids 251-314) distinct from the DNA-binding and steroid-binding domains. The comparable region of glucocorticoid receptor confers inhibitory actions on a hybrid receptor. Multiple, nonoverlapping sequences in the rat prolactin 5'-flanking genomic region that confer inhibition by both steroid hormones contain related cis-active elements that bind a common, tissue-specific positive transcription factor, called Pit-1. Experimental results indicate that positive and negative transcriptional effects of estrogen receptor are mediated by separate functional domains, and suggest the protein-protein interactions between steroid hormone receptors and other transcription factor(s) mediate inhibition.

Acute inflammation of the knee joint in the cat alters responses of flexor motoneurons to leg movements

1. This is a report of changes in reflex excitability of flexor motoneurons in response to innocuous mechanical stimuli following initiation of an acute experimental inflammation of the knee joint in the chloralose-anaesthetized cat spinalized at level T12. 2. Activity of functionally single alpha- or gamma- motoneurons, identified by ventral root stimulation, was recorded in filaments of the nerve to biceps semitendinosus before and after onset of an acute inflammation. The inflammation was evoked by injection into the knee cavity of the compounds kaolin and carrageenan. 3. Measurements were made of resting activity, responses to local pressure applied to parts of the upper or lower limb, and to flexion or extension movements at the knee joint before and after onset of the inflammation. In two experiments, one in which no inflammation was initiated, and another in which recordings were made only after the inflammation had fully developed, a survey of large numbers of neurons (44 alpha and 84 gamma) showed that under control conditions only 14% of alpha-motoneurons showed a response to mechanical stimulation compared with 41% of gamma-motoneurons. In the presence of an inflammation 41% of alpha-cells were responsive compared with 64% of gamma-cells. 4. Inflammation-induced changes in activity of motoneurons including both excitatory and inhibitory effects, took 1-2 h to fully develop. Excitatory effects included a rise in resting discharge, an increase in the response to local pressure, and an increased response to flexion and/or to extension of the knee. Inhibitory effects included falls in resting discharge and/or in the responses to leg movements. 5. For 35 cells identified as alpha-motoneurons and tested both before and after initiation of an inflammation, 20 remained unresponsive throughout the experiment, whereas 4 that had not responded during the control period began after inflammation to respond to local pressure and/or flexion/extension movements. Of 11 units that exhibited some response before inflammation, 8 showed an increase with inflammation, whereas 2 became unresponsive. 6. The inflammation had rather more dramatic effects on gamma-neurons. Many showed control responses to leg movements, and these were measurably modified by inflammation. Of 56 gamma-cells tested under control conditions, 26 were unresponsive to all stimuli, whereas 30 showed some form of response including activity during flexion and extension movements of the leg. Where responses were tested both before and after onset of an inflammation, 11 of 13 unresponsive units remained unresponsive.(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular basis of beta thalassemia in south China. Strategy for DNA analysis

The phenotype of beta thalassemia can be caused by over 40 different mutations. To set up a prenatal diagnosis program using DNA analysis, it is important to determine the type and frequency of mutation in a particular geographic area. We have delineated the molecular lesions that cause beta thalassemia in the Guangdong province of China, and found six mutations in four different haplotypes. The surprising finding that five of these mutations each occur in two different haplotypes suggests the occurrence of crossing over or gene conversion events at the beta-globin locus. The delineation of the haplotypes and mutations will permit the choice of the appropriate probes for prenatal detection of beta thalassemia in this part of China.