1: J Biol Chem. 2005 Jan 7;280(1):401-7. Epub 2004 Nov 4. 

The repressor element silencing transcription factor (REST)-mediated
transcriptional repression requires the inhibition of Sp1.

Plaisance V, Niederhauser G, Azzouz F, Lenain V, Haefliger JA, Waeber G,
Abderrahmani A.

Department of Internal Medicine, University of Lausanne, 1005 Lausanne,
Switzerland.

The terminal differentiation of neuronal and pancreatic beta-cells requires the
specific expression of genes that are targets of an important transcriptional
repressor named RE-1 silencing transcription factor (REST). The molecular
mechanism by which these REST target genes are expressed only in neuronal and
beta-cells and are repressed by REST in other tissues is a central issue in
differentiation program of neuronal and beta-cells. Herein, we showed that the
transcriptional factor Sp1 was required for expression of most REST target genes
both in insulin-secreting cells and neuronal-like cells where REST is absent.
Inhibition of REST in a non-beta and a non-neuronal cell model restored the
transcriptional activity of Sp1. This activity was also restored by trichostatin
A indicating the requirement of histone deacetylases for the REST-mediated
silencing of Sp1. Conversely, exogenous introduction of REST blocked
Sp1-mediated transcriptional activity. The REST inhibitory effect was mediated
through its C-terminal repressor domain, which could interact with Sp1. Taken
together, these data show that the inhibition of Sp1 by REST is required for the
silencing of its target genes expression in non-neuronal and in non-beta-cells.
We conclude that the interplay between REST and Sp1 determines the cell-specific
expression of REST target genes.

PMID: 15528196 [PubMed - indexed for MEDLINE]


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2: Eur J Biochem. 2003 Jan;270(1):2-9. 

RE-1 silencing transcription factor (REST) regulates human synaptophysin gene
transcription through an intronic sequence-specific DNA-binding site.

Lietz M, Hohl M, Thiel G.

Department of Medical Biochemistry and Molecular Biology, University of Saarland
Medical Center, Homburg, Germany.

Synaptophysin, one of the major proteins on synaptic vesicles, is ubiquitously
expressed throughout the brain. Synaptophysin and synapsin I, another synaptic
vesicle protein, are also expressed by retinoic acid-induced neuronally
differentiated P19 teratocarcinoma cells. Here, we show that inhibition of
histone deacetylase activity in P19 cells is sufficient to activate
transcription of the synaptophysin and synapsin I genes, indicating that
neuronal differentiation and impairment of histone deacetylases results in a
similar gene expression pattern. The transcription factor REST, a repressor of
neuronal genes in non-neuronal tissues, has been shown to function via
recruitment of histone deacetylases to the transcription unit, indicating that
modulation of the chromatin structure via histone deacetylation is of major
importance for REST function and neuron-specific gene transcription.
Furthermore, REST has been shown to be the major regulator of neuronal
expression of synapsin I. Here, we have identified a functional binding site for
REST in the first intron of the human synaptophysin gene indicating that REST
blocks human synaptophysin gene transcription through an intronic
neuron-specific silencer element. The synaptophysin promoter is, however, devoid
of neuron-specific genetic elements and directs transcription in both neuronal
and non-neuronal cells. Using a dominant-negative approach we have identified
the transcription factor Sp1 as one of the regulators responsible for
constitutive transcription of the human synaptophysin gene.

PMID: 12492469 [PubMed - indexed for MEDLINE]


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3: Brain Res Mol Brain Res. 2002 Nov 15;107(2):89-96. 

Effect of the ubiquitous transcription factors, SP1 and MAZ, on NMDA receptor
subunit type 1 (NR1) expression during neuronal differentiation.

Okamoto S, Sherman K, Bai G, Lipton SA.

Center for Neuroscience and Aging, The Burnham Institute, La Jolla, CA 92037,
USA.

The silencer factor NRSF/REST has been reported to restrict expression to
neurons of a variety of genes, including that encoding NMDA receptor subunit
type 1 (NR1), by suppressing transcription in nonneuronal cells. However, we
recently reported that in addition to the absence of NRSF/REST-binding activity,
another neuron-specific mechanism is necessary for high level expression of the
NR1 gene in neurons. In this study, we explored the mechanism of induction of
NR1 promoter activity during neuronal differentiation of the P19 cell line. We
identified a 27 base pair GC-rich region in the promoter as an important element
responsible for induction of the NR1 gene after neuronal differentiation. We
found that the ubiquitous transcription factors SP1 and MAZ bind to this GC-rich
region. Surprisingly, the binding activities of SP1 and MAZ are not remarkably
changed after neuronal differentiation. Mutations in the SP1 and MAZ sites
impair binding of SP1 and MAZ proteins and also decrease NR1 promoter activity.
These findings suggest that SP1 and MAZ mediate enhancement of NR1 promoter
activity during neuronal differentiation despite the fact that their binding
activity does not change.

PMID: 12425938 [PubMed - indexed for MEDLINE]


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4: J Biol Chem. 2001 Nov 9;276(45):42162-71. Epub 2001 Aug 31. 

Characterization of the rat GRIK5 kainate receptor subunit gene promoter and its
intragenic regions involved in neural cell specificity.

Chew LJ, Yuan X, Scherer SE, Qie L, Huang F, Hayes WP, Gallo V.

Section on Molecular and Cellular Neurobiology, Laboratory of Cellular and
Synaptic Neurophysiology, NICHD, National Institutes of Health, Bethesda,
Maryland 20892, USA.

The GRIK5 (glutamate receptor ionotropic kainate-5) gene encodes the
kainate-preferring glutamate receptor subunit KA2. The GRIK5 promoter is
TATA-less and GC-rich, with multiple consensus initiator sequences. Transgenic
mouse lines carrying 4 kilobases of the GRIK5 5'-flanking sequence showed lacZ
reporter expression predominantly in the nervous system. Reporter assays in
central glial (CG-4) and non-neural cells indicated that a 1200-base pair (bp)
5'-flanking region could sustain neural cell-specific promoter activity.
Transcriptional activity was associated with the formation of a transcription
factor IID-containing complex on an initiator sequence located 1100 bp upstream
of the first intron. In transfection studies, deletion of exonic sequences
downstream of the promoter resulted in reporter gene activity that was no longer
neural cell-specific. When placed downstream of the GRIK5 promoter, a 77-bp
sequence from the deleted fragment completely silenced reporter expression in
NIH3T3 fibroblasts while attenuating activity in CG-4 cells. Analysis of the
77-bp sequence revealed a functional SP1-binding site and a sequence resembling
a neuron-restrictive silencer element. The latter sequence, however, did not
display cell-specific binding of REST-like proteins. Our studies thus provide
evidence for intragenic control of GRIK5 promoter activity and suggest that
elements contributing to tissue-specific expression are contained within the
first exon.

PMID: 11533047 [PubMed - indexed for MEDLINE]


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5: Brain Res Mol Brain Res. 2001 Jun 20;90(2):174-86. 

Cell-type non-selective transcription of mouse and human genes encoding
neural-restrictive silencer factor.

Kojima T, Murai K, Naruse Y, Takahashi N, Mori N.

Department of Molecular Genetics, National Institute for Longevity Sciences,
Gengo 36-3, Morioka, Oobu, 474-8522, Aichi, Japan.

Neural-restrictive silencer (NRS) has been identified in at least twenty
neuron-specific genes, and its nuclear DNA-binding factor, NRSF (also known as
RE1-silencing transcription factor (REST)), has been cloned from human and rat,
and was shown to repress transcription by recruiting corepressors mSin3 and/or
CoREST via its N- and C-terminal domains, leading to chromatin reorganization by
mSin3-associated histone deacetylase, HDAC. However, it is largely unknown how
NRSF gene expression is regulated. To elucidate the mechanisms for gene
expression of NRSF, we isolated the transcriptional unit of the NRSF gene from
mouse and human, identified three 5'-non-coding exons in addition to three
coding exons, determined transcription start sites, and identified two basal
promoter activities in the upstream of the first two non-coding exons. Both
promoters functioned equally in neuronal and non-neuronal cells, suggesting that
levels of initial transcripts of NRSF gene are similar in neuronal and
non-neuronal cells. These results suggest that the level of NRSF gene expression
is not determined by transcription per se, and rather is modulated at the
post-transcriptional level, e.g. splicing, mRNA stability, and/or
post-translational modifications, in a cell-specific manner. Consistent with
this idea, NRSF protein was apparently present even in neuronal cells and
tissues, but was unable to bind to the NRS element, suggesting that NRSF is
regulated at least in part post-translationally.

PMID: 11406295 [PubMed - indexed for MEDLINE]


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6: Biochem Biophys Res Commun. 2001 May 18;283(4):928-32. 

The neuron restrictive silencer factor can act as an activator for dynamin I
gene promoter activity in neuronal cells.

Yoo J, Jeong MJ, Lee SS, Lee KI, Kwon BM, Kim DS, Park YM, Han MY.

Cell Biology Laboratory, Korea Research Institute of Bioscience and
Biotechnology, Yusung, Taejon, 305-600, Korea.

The neuron restrictive silencer element (NRSE) has been identified in several
neuronal genes and confers neuron specificity by silencing transcription in
nonneuronal cells. We have previously reported that Sp1 and an NF-kappaB-like
element (NE-1) are required for the promoter activity of mouse dynamin I gene.
In the present study, we found that the upstream regulatory region of the
dynamin I promoter has an NRSE-like sequence and showed that neuron restrictive
silencer factor (NRSF) binds to this element in neuronal cells as well as in
nonneuronal cells. We also showed that NRSF activates the promoter activity of
dynamin I gene in neuronal cells. From the results in this study, we suggest
that NRSE might be involved in the neuron restriction of dynamin I expression,
and NRSF could act as an activator for promoter activity of dynamin I gene in
neuronal cells. Copyright 2001 Academic Press.

PMID: 11350074 [PubMed - indexed for MEDLINE]


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7: Arch Biochem Biophys. 2000 May 1;377(1):69-79. 

Interaction of Ap1, Ap2, and Sp1 with the regulatory regions of the human
pro-alpha1(I) collagen gene.

Vergeer WP, Sogo JM, Pretorius PJ, de Vries WN.

School for Chemistry and Biochemistry, Potchefstroom University, Potchefstroom,
2520, South Africa.

In the pro-alpha1(I) collagen gene a number of cis-regulatory elements, which
interact with a variety of trans-acting factors, are present in the promoter and
first intron. We have undertaken a comprehensive study of Sp1, Ap1, and Ap2
binding in the region spanning -442 to +1697 nt. DNase I footprinting analysis
revealed these factors bind with varying affinities to some of the potential
sites: Sp1 binds to 16 of 34 potential sites, Ap2 binds to 22 of 40 potential
binding sites, and Ap1 binds to its only potential site. The Sp1 sites were
mostly clustered in the intron region, while the Ap2 sites were clustered in the
promoter region. Transmission electron microscopic analysis of DNA-protein
complexes not only confirmed these results, but also clearly showed that
heterologous and/or homologous protein-protein interactions between Sp1 and/or
Ap2 bring the promoter and intron in contact with each other, with the resulting
looping out of the intervening DNA. This strongly suggests that the DNA-looping
model is an explanation for the orientation preference of the enhancing element
in the first intron as these interactions possibly create an optimum environment
for the binding of the rest of the transcriptional machinery. Copyright 2000
Academic Press.

PMID: 10775443 [PubMed - indexed for MEDLINE]


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8: Prog Nucleic Acid Res Mol Biol. 1998;61:309-44. 

Structural organization and transcription regulation of nuclear genes encoding
the mammalian cytochrome c oxidase complex.

Lenka N, Vijayasarathy C, Mullick J, Avadhani NG.

Department of Animal Biology, School of Veterinary Medicine, University of
Pennsylvania, Philadelphia 19104, USA.

Cytochrome c Oxidase (COX) is the terminal component of the bacterial as well as
the mitochondrial respiratory chain complex that catalyzes the conversion of
redox energy to ATP. In eukaryotes, the oligomeric enzyme is bound to
mitochondrial innermembrane with subunits ranging from 7 to 13. Thus, its
biosynthesis involves a coordinate interplay between nuclear and mitochondrial
genomes. The largest subunits, I, II, and III, which represent the catalytic
core of the enzyme, are encoded by the mitochondrial DNA and are synthesized
within the mitochondria. The rest of the smaller subunits implicated in the
regulatory function are encoded on the nuclear DNA and imported into
mitochondria following their synthesis in the cytosol. Some of the nuclear coded
subunits are expressed in tissue and developmental specific isologs. The
ubiquitous subunits IV, Va, Vb, VIb, VIc, VIIb, VIIc, and VIII (L) are detected
in all the tissues, although the mRNA levels for the individual subunits vary in
different tissues. The tissue specific isologs VIa (H), VIIa (H), and VIII (H)
are exclusive to heart and skeletal muscle. cDNA sequence analysis of nuclear
coded subunits reveals 60 to 90% conservation among species both at the amino
acid and nucleotide level, with the exception of subunit VIII, which exhibits 40
to 80% interspecies homology. Functional genes for COX subunits IV, Vb, VIa 'L'
& 'H', VIIa 'L' & 'H', VIIc and VIII (H) from different mammalian species and
their 5' flanking putative promoter regions have been sequenced and extensively
characterized. The size of the genes range from 2 to 10 kb in length. Although
the number of introns and exons are identical between different species for a
given gene, the size varies across the species. A majority of COX genes
investigated, with the exception of muscle-specific COXVIII(H) gene, lack the
canonical 'TATAA' sequence and contain GC-rich sequences at the immediate
upstream region of transcription start site(s). In this respect, the promoter
structure of COX genes resemble those of many house-keeping genes. The
ubiquitous COX genes show extensive 5' heterogeneity with multiple transcription
initiation sites that bind to both general as well as specialized transcription
factors such as YY1 and GABP (NRF2/ets). The transcription activity of the
promoter in most of the ubiquitous genes is regulated by factors binding to the
5' upstream Sp1, NRF1, GABP (NRF2), and YY1 sites. Additionally, the murine
COXVb promoter contains a negative regulatory region that encompasses the
binding motifs with partial or full consensus to YY1, GTG, CArG, and ets.
Interestingly, the muscle-specific COX genes contain a number of striated
muscle-specific regulatory motifs such as E box, CArG, and MEF2 at the proximal
promoter regions. While the regulation of COXVIa (H) gene involves factors
binding to both MEF2 and E box in a skeletal muscle-specific fashion, the
COXVIII (H) gene is regulated by factors binding to two tandomly duplicated E
boxes in both skeletal and cardiac myocytes. The cardiac-specific factor has
been suggested to be a novel bHLH protein. Mammalian COX genes provide a
valuable system to study mechanisms of coordinated regulation of nuclear and
mitochondrial genes. The presence of conserved sequence motifs common to several
of the nuclear genes, which encode mitochondrial proteins, suggest a possible
regulatory function by common physiological factors like heme/O2/carbon source.
Thus, a well-orchestrated regulatory control and cross talks between the nuclear
and mitochondrial genomes in response to changes in the mitochondrial metabolic
conditions are key factors in the overall regulation of mitochondrial
biogenesis.

Publication Types:
    Review

PMID: 9752724 [PubMed - indexed for MEDLINE]


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9: J Neurosci. 1998 Sep 1;18(17):6723-39. 

Transcriptional regulation of the GluR2 gene: neural-specific expression,
multiple promoters, and regulatory elements.

Myers SJ, Peters J, Huang Y, Comer MB, Barthel F, Dingledine R.

Department of Pharmacology, Emory University, Atlanta, Georgia 30322, USA.

To understand how neurons control the expression of the AMPA receptor subunit
GluR2, we cloned the 5' proximal region of the rat gene and investigated GluR2
promoter activity by transient transfection. RNase protection and primer
extension of rat brain mRNA revealed multiple transcription initiation sites
from -340 to -481 bases upstream of the GluR2 AUG codon. The relative use of 5'
start sites was different in cortex and cerebellum, indicating complexity of
GluR2 transcript expression among different sets of neurons. When GluR2 promoter
activity was investigated by plasmid transfection into cultured cortical
neurons, cortical glia, and C6 glioma cells, the promoter construct with the
strongest activity, per transfected cell, was 29.4-fold (+/- 3.7) more active in
neurons than in non-neural cells. Immunostaining of cortical cultures showed
that >97% of the luciferase-positive cells also expressed the neuronal marker
MAP-2. Evaluation of internal deletion and substitution mutations identified a
functional repressor element I RE1-like silencer and functional Sp1 and nuclear
respiratory factor-1 (NRF-1) elements within a GC-rich proximal GluR2 promoter
region. The GluR2 silencer reduced promoter activity in glia and non-neuronal
cell lines by two- to threefold, was without effect in cortical neurons, and
could bind the RE1-silencing transcription factor (REST) because cotransfection
of REST into neurons reduced GluR2 promoter activity in a silencer-dependent
manner. Substitution of the GluR2 silencer by the homologous NaII RE1 silencer
further reduced GluR2 promoter activity in non-neuronal cells by 30-47%. Maximal
positive GluR2 promoter activity required both Sp1 and NRF-1 cis elements and an
interelement nucleotide bridge sequence. These results indicate that GluR2
transcription initiates from multiple sites, is highly neuronal selective, and
is regulated by three regulatory elements in the 5' proximal promoter region.

PMID: 9712644 [PubMed - indexed for MEDLINE]


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10: J Biol Chem. 1998 Jan 9;273(2):1086-91. 

Single-stranded DNA-binding proteins and neuron-restrictive silencer factor
participate in cell-specific transcriptional control of the NMDAR1 gene.

Bai G, Norton DD, Prenger MS, Kusiak JW.

Molecular Neurobiology Unit, Gerontology Research Center, NIA, National
Institutes of Health, Baltimore, Maryland 21224, USA. gbai@rics.bhw.harvard.edu

Our previous studies revealed that a proximal region of the N-methyl-D-aspartate
receptor 1 (NMDAR1) promoter is important for cell-type-specific expression. We
have now explored the contributions of several regulatory elements to this
specificity. Deletion of the neuron-restrictive silencer element partially
relieved the suppression of promoter activity in C6 glioma and HeLa cells. An
overlapping G(C/G)G/tandem Sp1-containing region crucial for both basal and
nerve growth factor (NGF)-regulated promoter activity specifically bound nuclear
proteins on its purine-rich sense strand. A faster migrating complex,
single-stranded binding protein complex 1 (SBPC1), was highly enriched in HeLa
cells, whereas a slower migrating complex, SBPC2, was enriched in PC12 cells. A
high ratio of 2/1 complex correlated with a high level of promoter activity. NGF
treatment of PC12 cells reduced SBPC1 but increased SBPC2. Competition
experiments showed that the SBPC1 binding required a dG4 sequence and the SBPC2
needed a core of TG3A plus a 5'-flanking sequence. Single-stranded DNA
encompassing TG3A and/or dG4 specifically suppressed cotransfected NMDAR1
promoter activity. UV cross-linking studies indicated that a 31.5-kDa protein
mainly formed SBPC1, whereas SBPC2 contained several larger proteins. Our
results suggest that neuron-restrictive silencer factor and single-stranded
DNA-binding proteins may both play a role in cell-type specificity of the NMDAR1
gene, and the latter may also be involved in basal and NGF-regulated activity.

PMID: 9422773 [PubMed - indexed for MEDLINE]


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11: Endocrinology. 1996 Sep;137(9):3897-905. 

cis-acting elements and trans-acting proteins in the transcription of chorionic
gonadotropin/luteinizing hormone receptor gene in human choriocarcinoma cells
and placenta.

Hu YL, Lei ZM, Rao CV.

Department of Obstetrics and Gynecology, University of Louisville School of
Medicine, Kentucky 40292, USA.

We investigated the cis-acting elements and trans-acting proteins responsible
for a higher basal rate of transcription of hCG/LH receptor gene in human
choriocarcinoma JEG-3 cells compared with normal term pregnancy placenta.
Sequential deletion of the 5'-flanking region of the gene revealed that there
are three negative control regions (NCRs) designated NCR1 (-1457 to -1373 bp),
NCR2 (-1051 to -835 bp), and NCR3 (-480 to -184 bp), and a promoter (-184 to -1
bp). NCR3 was more inhibitory than the other two; nearly 60-70% of the
inhibitory activity resides in a sequence between -480 to -276 bp, and the rest
resides in the sequence between -276 to -184 bp. Gel mobility shift assays
showed that the nuclear extracts from JEG-3 cells contained proteins that form
three complexes with NCR1, two with NCR2, and six with NCR3. Many of the
proteins that form the complexes in NCR3 are shared with the other two NCRs.
Most of the proteins that form these complexes are less abundant in nuclear
extracts from JEG-3 cells than in those from placenta. The JEG-3 cell nuclear
extracts also contained proteins that form three complexes with the proximal
promoter of the hCG/LH receptor gene. These proteins were identified as Ap2,
Ap2-like I, and Sp1 from the competition studies with synthetic excess unlabeled
Ap2, Sp1, and CTF/NF1 consensus oligodeoxynucleotides and/or supershift in gel
mobility assays with anti-Ap2 antibody. Although the JEG-3 cell nuclear extracts
contained abundant Ap2-like protein I and low levels of Ap2 and Sp1 proteins,
the placental nuclear extracts contained low levels of Ap2-like protein I and
very low to nondetectable levels of Ap2 and Sp1 proteins. Deoxyribonuclease I
footprinting revealed that the nuclear extracts from JEG-3 cells and placent
protected the -116 to -93 bp and -65 to -45 bp regions in the proximal promoter
of the hCG/LH receptor gene that contain Sp1 and Ap2 binding sites,
respectively. However, the nuclear extracts from placenta only partially
protected these regions, which is consistent with lower levels of proteins that
bind to the proximal promoter of the gene. In summary, we conclude that the
presence of low levels of proteins that bind to the NCRs and the high levels of
proteins, especially Ap2-like I, that bind to the proximal promoter can
potentially explain higher transcription of the hCG/LH receptor gene in JEG-3
cells compared with that in normal term pregnancy human placenta.

PMID: 8756564 [PubMed - indexed for MEDLINE]


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12: Genomics. 1996 Jul 1;35(1):182-8. 

The structure of the prostaglandin EP4 receptor gene and related pseudogenes.

Foord SM, Marks B, Stolz M, Bufflier E, Fraser NJ, Lee MG.

Receptor Systems Unit, Glaxo Wellcome Medicines Research Centre, Gunnels Wood
Road, Stevenage, Hertfordshire, SG1 2NY, England.

The EP4 prostaglandin receptor (EP4R) is a member of the seven transmembrane
receptor superfamily. We have obtained the human EP4 receptor gene sequence and
determined its structure relative to EP4R cDNA synthesized from peripheral blood
lymphocytes. The EP4R gene spans approximately 22 kb and consists of three exons
separated by two introns. The first exon (530 bp) is noncoding. After an intron
of 472 bp, the second exon contains a short (43 bp) 5' sequence before a
289-amino-acid open reading frame (ORF). An 11.5-kb intron is found at the end
of transmembrane 6, and the rest of the ORF is in exon 3. The gene structure is
analogous to those of the thromboxane, PGI, and PGD receptors. The deduced
initiation site does not contain a conventional TATA box but is 70% GC-rich and
contains CCAAT boxes, SP1 and AP2 motifs, and motifs consistent with activation
by proinflammatory cytokines. Southern blot analysis of human genomic DNA shows
two genes with homology to the EP4R gene. Both appear to be pseudogenes with 70%
amino acid identity to the EP4R up to the "ERY" sequence at the end of
transmembrane 3, where an Alu-like repetitive sequence element was found. The
ORF sequence is also interrupted by a stop codon. The pseudogenes differ in that
one contains a second "repetitive element" (a line 1 repeat) in the 5' end of
the ORF. Northern blot analysis of human mRNA using a pseudogene probe showed
hybridization only to the EP4 receptor transcript. PCR also failed to detect
expression of either pseudogene. This study defines the gene structure of EP4R
and suggests the existence of two related pseudogenes.

PMID: 8661119 [PubMed - indexed for MEDLINE]


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13: Placenta. 1987 Jul-Aug;8(4):427-32. 

Studies on the elevated amniotic fluid SP1 in Meckel's syndrome: modified
glycosylation of SP1.

Heikinheimo M, Jalanko H, Renlund M, Rapola J, Wahlstrom T.

Department of Bacteriology and Immunology, Children's Hospital, Helsinki,
Finland.

Pregnancy-specific beta 1-glycoprotein (Schwangerschaftsprotein, SP1) is
elevated in the amniotic fluid in Meckel's syndrome. In an attempt to clarify
this phenomenon, we studied fetal tissues by immunohistochemistry for the
distribution of SP1 in normal fetuses and fetuses with Meckel's syndrome. The
amount of SP1 was increased in two out of ten Meckel placentae, as
semiquantitatively shown by the immunoperoxidase method, but was normal in the
rest of the cases. There was no difference in the SP1 distribution or content in
the other fetal tissues studied. Fetal cerebrospinal fluid contained only very
low levels of SP1 and thus cannot provide a source for elevated amniotic fluid
SP1. In addition, binding of amniotic fluid SP1 to concanavalin A (Con-A) was
studied in pregnancies with normal fetuses and Meckel's syndrome using affinity
chromatography. The proportion not bound to Con-A in normal amniotic fluids
decreased with advancing gestation and was lowest when the total SP1
concentrations were highest. An especially low percentage of SP1 not bound to
Con A was found in Meckel's syndrome, suggesting an altered carbohydrate
structure of SP1 in these amniotic fluids.

PMID: 3317390 [PubMed - indexed for MEDLINE]


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14: In Vitro Cell Dev Biol. 1986 Feb;22(2):100-6. 

Cytoskeletal markers and specific protein production in cells cultured from
human first and third trimester placentae.

Vettenranta K, von Koskull H, Heikinheimo M, Raivio KO.

In primary, short-term cultures derived from first and third trimester
placentae, 60 to 90 and 70 to 95%, respectively, of the total cell population
positively stain for cytokeratin intermediate filaments, typical of epithelial,
i.e. trophoblastic cells. The rest of the cells express only vimentin
intermediate filaments and thus are of mesenchymal origin. Only the
cytokeratin-positive cells express human chorionic gonadotropin (hCG), whereas
both the epithelial and the mesenchymal cells stain positively for
pregnancy-specific beta-1-glycoprotein (SP1). Cytokeratin-negative and
vimentin-positive cell overgrowth is observed in cultures derived from first and
early third trimester placentae. The cells constituting the monolayer thus
formed are of fetal origin as evidenced by the expression of Y-body in over 80%
of them. The cultured cells synthesize and secrete hCG and SP1. The activity of
these trophoblast-specific functions is inversely proportional to the
gestational age of the placenta. Production of specific proteins and expression
of intermediate filaments are proposed as criteria for defining the nature and
origin of placental cells in primary, short-term cultures.

PMID: 2419301 [PubMed - indexed for MEDLINE]


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