scholarly journals Cytosine methylation of an Sp1 site contributes to organ-specific and cell-specific regulation of expression of the lung epithelial gene T1α

2000 ◽  
Vol 350 (3) ◽  
pp. 883-890 ◽  
Author(s):  
Yu-Xia CAO ◽  
Jyh-Chang JEAN ◽  
Mary C. WILLIAMS
Keyword(s):  
Cytosine Methylation ◽  
Expression Patterns ◽  
Adult Brain ◽  
Proximal Promoter ◽  
Alveolar Type ◽  
Type I ◽  
Regulation Of Expression ◽  
Lung Epithelial ◽  
Specific Regulation

Several recent observations have suggested that cytosine methylation has a role in the in vivo transcriptional regulation of cell-specific genes in normal cells. We hypothesized that methylation regulates T1α, a gene expressed primarily in lung in adult rodents. In fetuses T1α is expressed in several organs, including the entire nervous system, but during development its expression is progressively restricted to lung alveolar type I epithelial cells, some osteoblasts and choroid plexus. Here we report that T1α is methylated at a key Sp1 site in the proximal promoter in cells and organs, including brain, where no gene expression is detectable. Conversely, in T1α-expressing cells, these sites are not methylated. In embryonic brain T1α is unmethylated and expressed; in adult brain the gene is methylated and not expressed. In lung epithelial cell lines, methylation of the T1α promoter in vitro decreases expression by approx. 50% (the maximum suppression being 100%). Analysis of mutated promoter constructs indicates that a single Sp1 site in the proximal promoter provides all or most of the methylation-sensitive gene silencing. We conclude that, in addition to regulation by transcription factors, cytosine methylation has a role in the complex expression patterns of this gene in intact animals and primary cells.

scholarly journals Rat alveolar type I cells proliferate, express OCT-4, and exhibit phenotypic plasticity in vitro

2009 ◽  
Vol 297 (6) ◽  
pp. L1045-L1055 ◽  
Author(s):  
Robert F. Gonzalez ◽  
Lennell Allen ◽  
Leland G. Dobbs
Keyword(s):  
Phenotypic Plasticity ◽  
Expression Patterns ◽  
Clara Cell ◽  
Cell Phenotype ◽  
Alveolar Type ◽  
Type I ◽  
Aquaporin 5 ◽  
Internal Surface Area ◽  
Phenotypic Markers

Alveolar type I (TI) cells are large, squamous cells that cover 95–99% of the internal surface area of the lung. Although TI cells are believed to be terminally differentiated, incapable of either proliferation or phenotypic plasticity, TI cells in vitro both proliferate and express phenotypic markers of other differentiated cell types. Rat TI cells isolated in purities of >99% proliferate in culture, with a sixfold increase in cell number before the cells reach confluence; >50% of the cultured TI cells are Ki67+. At cell densities of 1–2 cells/well, ∼50% of the cells had the capacity to form colonies. Under the same conditions, type II cells do not proliferate. Cultured TI cells express RTI40 and aquaporin 5, phenotypic markers of the TI cell phenotype. By immunofluorescence, Western blotting, and Q-PCR, TI cells express OCT-4A (POU5F1), a transcription factor associated with maintenance of the pluripotent state in stem cells. Based on the expression patterns of various marker proteins, TI cells are distinct from either of two recently described putative pulmonary multipotent cell populations, the bronchoalveolar stem cell or the OCT-4+ stem/progenitor cell. Although TI cells in adult rat lung tissue do not express either surfactant protein C (SP-C) or CC10, respective markers of the TII and Clara cell phenotypes, in culture TI cells can be induced to express both SP-C and CC10. Together, the findings that TI cells proliferate and exhibit phenotypic plasticity in vitro raise the possibility that TI cells may have similar properties in vivo.

scholarly journals Single-cell analysis of human lung epithelia reveals concomitant expression of the SARS-CoV-2 receptor ACE2 with multiple virus receptors and scavengers in alveolar type II cells

2020 ◽  
Author(s):  
Guangchun Han ◽  
Ansam Sinjab ◽  
Warapen Treekitkarnmongkol ◽  
Patrick Brennan ◽  
Kieko Hara ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Single Cell ◽  
Expression Patterns ◽  
Severe Pneumonia ◽  
Lung Epithelial Cells ◽  
Chronic Obstructive ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii ◽  
Lung Epithelial

ABSTRACTThe novel coronavirus SARS-CoV-2 was identified as the causative agent of the ongoing pandemic COVID 19. COVID-19-associated deaths are mainly attributed to severe pneumonia and respiratory failure. Recent work demonstrated that SARS-CoV-2 binds to angiotensin converting enzyme 2 (ACE2) in the lung. To better understand ACE2 abundance and expression patterns in the lung we interrogated our in-house single-cell RNA-sequencing dataset containing 70,085 EPCAM+ lung epithelial cells from paired normal and lung adenocarcinoma tissues. Transcriptomic analysis revealed a diverse repertoire of airway lineages that included alveolar type I and II, bronchioalveolar, club/secretory, quiescent and proliferating basal, ciliated and malignant cells as well as rare populations such as ionocytes. While the fraction of lung epithelial cells expressing ACE2 was low (1.7% overall), alveolar type II (AT2, 2.2% ACE2+) cells exhibited highest levels of ACE2 expression among all cell subsets. Further analysis of the AT2 compartment (n = 27,235 cells) revealed a number of genes co-expressed with ACE2 that are important for lung pathobiology including those associated with chronic obstructive pulmonary disease (COPD; HHIP), pneumonia and infection (FGG and C4BPA) as well as malarial/bacterial (CD36) and viral (DMBT1) scavenging which, for the most part, were increased in smoker versus light or non-smoker cells. Notably, DMBT1 was highly expressed in AT2 cells relative to other lung epithelial subsets and its expression positively correlated with ACE2. We describe a population of ACE2-positive AT2 cells that co-express pathogen (including viral) receptors (e.g. DMBT1) with crucial roles in host defense thus comprising plausible phenotypic targets for treatment of COVID-19.

scholarly journals EphB6 Regulates TFEB-Lysosomal Pathway and Survival of Disseminated Indolent Breast Cancer Cells

Cancers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1079
Author(s):  
Manuela Zangrossi ◽  
Patrizia Romani ◽  
Probir Chakravarty ◽  
Colin D.H. Ratcliffe ◽  
Steven Hooper ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Epithelial Cells ◽  
Cancer Cells ◽  
Lung Epithelial Cells ◽  
Late Relapse ◽  
Alveolar Type ◽  
Type I ◽  
Extrinsic Factors ◽  
Lung Epithelial

Late relapse of disseminated cancer cells is a common feature of breast and prostate tumors. Several intrinsic and extrinsic factors have been shown to affect quiescence and reawakening of disseminated dormant cancer cells (DDCCs); however, the signals and processes sustaining the survival of DDCCs in a foreign environment are still poorly understood. We have recently shown that crosstalk with lung epithelial cells promotes survival of DDCCs of estrogen receptor-positive (ER+) breast tumors. By using a lung organotypic system and in vivo dissemination assays, here we show that the TFEB-lysosomal axis is activated in DDCCs and that it is modulated by the pro-survival ephrin receptor EphB6. TFEB lysosomal direct targets are enriched in DDCCs in vivo and correlate with relapse in ER+ breast cancer patients. Direct coculture of DDCCs with alveolar type I-like lung epithelial cells and dissemination in the lung drive lysosomal accumulation and EphB6 induction. EphB6 contributes to survival, TFEB transcriptional activity, and lysosome formation in DDCCs in vitro and in vivo. Furthermore, signaling from EphB6 promotes the proliferation of surrounding lung parenchymal cells in vivo. Our data provide evidence that EphB6 is a key factor in the crosstalk between disseminated dormant cancer cells and the lung parenchyma and that the TFEB-lysosomal pathway plays an important role in the persistence of DDCCs.

scholarly journals GDF-9 and BMP-15 mRNA Levels in Canine Cumulus Cells Related to Cumulus Expansion and the Maturation Process

Animals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 462 ◽  
Author(s):  
George Ramirez ◽  
Jaime Palomino ◽  
Karla Aspee ◽  
Monica De los Reyes
Keyword(s):  
Gene Expression ◽  
Estrous Cycle ◽  
Expression Patterns ◽  
Cumulus Cells ◽  
Mrna Levels ◽  
Cumulus Expansion ◽  
Polymerase Chain ◽  
Specific Regulation ◽  
Reproductive Phases

The competence to undergo expansion is a characteristic of cumulus cells (CCs). The aim was to investigate the expression of GDF-9 and BMP-15 mRNA in canine cumulus cells in relation to cumulus expansion and meiotic development over the estrous cycle. CCs were recovered from nonmatured and in vitro-matured (IVM) dog cumulus oocyte complexes (COCs), which were obtained from antral follicles at different phases of the estrous cycle. Quantitative real-time polymerase chain reaction (q-PCR) was used to evaluate the relative abundance of GDF-9 and BMP-15 transcripts from the CCs with or without signs of expansion. The results were evaluated by ANOVA and logistic regression. The maturity of the oocyte and the expansion process affected the mRNA levels in CCs. There were differences (p < 0.05) in GDF-9 and BMP-15 gene expression in CCs isolated from nonmatured COCs when comparing the reproductive phases. Lower mRNA levels (p < 0.05) were observed in anestrus and proestrus in comparison to those in estrus and diestrus. In contrast, when comparing GDF-9 mRNA levels in IVM COCs, no differences were found among the phases of the estrous cycle in expanded and nonexpanded CCs (p < 0.05). However, the highest (p < 0.05) BMP-15 gene expression in CCs that did not undergo expansion was exhibited in anestrus and the lowest (p < 0.05) expression was observed in estrus in expanded CCs. Although the stage of the estrous cycle did not affect the second metaphase (MII )rates, the expanded CCs obtained at estrus coexisted with higher percentages of MII (p < 0.05). In conclusion, the differential expression patterns of GDF-9 and BMP-15 mRNA transcripts might be related to cumulus expansion and maturation processes, suggesting specific regulation and temporal changes in their expression.

Mechanisms and regulation of ion transport in adult mammalian alveolar type II pneumocytes

1991 ◽  
Vol 261 (5) ◽  
pp. C727-C738 ◽  
Author(s):  
S. Matalon
Keyword(s):  
Epithelial Transport ◽  
Cultured Cells ◽  
Basolateral Membrane ◽  
Alveolar Epithelium ◽  
Alveolar Type ◽  
Type I ◽  
Type Ii ◽  
Epithelial Lining ◽  
Epithelial Lining Fluid

The adult alveolar epithelium consists of type I and type II (ATII) pneumocytes that form a tight barrier, which severely restricts the entry of lipid-insoluble molecules from the interstitial to the alveolar space. Current in vivo and in vitro evidence indicates that the alveolar epithelium is also an absorptive epithelium, capable of transporting Na+ from the alveolar lumen, which is bathed by a small amount of epithelial lining fluid, to the interstitial space. The in situ localization of Na(+)-K(+)-ATPase activity in ATII cells and the fact that these cells are involved in a number of crucial functions, such as surfactant secretion and alveolar remodeling after injury, led investigators to examine their transport characteristics. Radioactive flux studies, in both freshly isolated and cultured cells, and bioelectric measurements in ATII cells grown on porous supports indicate that they transport Na+ according to the Koefoed-Johnsen and Ussing model of epithelial transport. Na+ enters the apical membrane, because of the favorable electrochemical gradient, through Na+ cotransporters, a Na(+)-H+ antiport, and cation channels and is pumped across the basolateral membrane by a ouabain-sensitive Na(+)-K+ pump. Na+ transport is enhanced by substances that increase intracellular adenosine 3',5'-cyclic monophosphate. In addition to Na+ transporters, ATII cells contain several transporters that regulate their intracellular pH, including a H(+)-ATPase, which may explain the low pH of the epithelial lining fluid. The absorptive properties of ATII cells may play an important role in regulating the degree of alveolar fluid in health and disease.

scholarly journals Identification of protein IT of the intestinal cytoskeleton as a novel type I cytokeratin with unusual properties and expression patterns.

1990 ◽  
Vol 111 (2) ◽  
pp. 567-580 ◽  
Author(s):  
R Moll ◽  
D L Schiller ◽  
W W Franke
Keyword(s):  
Mammalian Species ◽  
Expression Patterns ◽  
Prostate Gland ◽  
Coiled Coil ◽  
Immunological Methods ◽  
Type I ◽  
Peptide Fragments ◽  
Binding Assays ◽  
Human Intestinal Epithelium

A major cytoskeletal polypeptide (Mr approximately 46,000; protein IT) of human intestinal epithelium was characterized by biochemical and immunological methods. The polypeptide, which was identified as a specific and genuine mRNA product by translation in vitro, reacted, in immunoblotting after SDS-PAGE, only with one of numerous cytokeratin (CK) antisera tested but with none of many monoclonal CK antibodies. In vitro, it formed heterotypic complexes with the type II CK 8, as shown by blot binding assays and gel electrophoresis in 4 M urea, and these complexes assembled into intermediate filaments (IFs) under appropriate conditions. A chymotrypsin-resistant Mr approximately 38,000 core fragment of protein IT could be obtained from cytoskeletal IFs, indicating its inclusion in a coiled coil. Antibodies raised against protein IT decorated typical CK fibril arrays in normal and transformed intestinal cells. Four proteolytic peptide fragments obtained from purified polypeptide IT exhibited significant amino acid sequence homology with corresponding regions of coils I and II of the rod domain of several other type I CKs. Immunocytochemically, the protein was specifically detected as a prominent component of intestinal and gastric foveolar epithelium, urothelial umbrella cells, and Merkel cells of epidermis. Sparse positive epithelial cells were noted in the thymus, bronchus, gall bladder, and prostate gland. The expression of protein IT was generally maintained in primary and metastatic colorectal carcinomas as well as in cell cultures derived therefrom. A corresponding protein was also found in several other mammalian species. We conclude that polypeptide IT is an integral IF component which is related, though somewhat distantly, to type I CKs, and, therefore, we propose to add it to the human CK catalogue as CK 20.

scholarly journals Expression of the unique NCAM VASE exon is independently regulated in distinct tissues during development.

1990 ◽  
Vol 111 (5) ◽  
pp. 2089-2096 ◽  
Author(s):  
S J Small ◽  
R Akeson
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Alternative Splicing ◽  
Significant Proportion ◽  
Adult Brain ◽  
Alternative Exon ◽  
Rat Tissues ◽  
Regulation Of Expression ◽  
Specific Expression

During development of the rat central nervous system, neural cell adhesion molecule (NCAM) mRNAs containing in the extracellular domain a 30-bp alternative exon, here named VASE, replace RNAs that lack this exon. The presence of this alternative exon between previously described exons 7 and 8 changes the predicted loop structure of the derived polypeptide from one resembling an immunoglobulin constant region domain to one resembling an immunoglobulin variable domain. This change could have significant effects on NCAM polypeptide function and cell-cell interaction. In this report we test multiple rat tissues for the presence of additional alternative exons at this position and also examine the regulation of splicing of the previously described exon. To sensitively examine alternative splicing, polymerase chain reactions (PCRs) with primers flanking the exon 7/exon 8 alternative splicing site were performed. Four categories of RNA samples were tested for new exons: whole brain from embryonic day 11 to adult, specific brain regions dissected from adult brain, clonal lines of neural cells in vitro, and muscle cells and tissues cultured in vitro and obtained by dissection. Within the limits of the PCR methodology, no evidence for any alternative exon other than the previously identified VASE was obtained. The regulation of expression of this exon was found to be complex and tissue specific. Expression of the 30-bp exon in the heart and nervous system was found to be regulated independently; a significant proportion of embryonic day 15 heart NCAM mRNAs contain VASE while only a very small amount of day 15 nervous system mRNAs contain VASE. Some adult central nervous system regions, notably the olfactory bulb and the peripheral nervous system structures adrenal gland and dorsal root ganglia, express NCAM which contains very little VASE. VASE is undetectable in NCAM PCR products from the olfactory epithelium. Other nervous system regions express significant quantities of NCAM both with and without VASE. Clonal cell lines in culture generally expressed very little VASE. These results indicate that a single alternative exon, VASE, is found in NCAM immunoglobulin-like loop 4 and that distinct tissues and nervous system regions regulate expression of VASE independently both during development and in adult animals.

scholarly journals EphB6 regulates TFEB-lysosomal pathway and survival of disseminated quiescent breast cancer cells

2020 ◽  
Author(s):  
Manuela Zangrossi ◽  
Probir Chakravarty ◽  
Patrizia Romani ◽  
Colin D.H. Ratcliffe ◽  
Steven Hooper ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Epithelial Cells ◽  
Cancer Cells ◽  
Lung Epithelial Cells ◽  
Late Relapse ◽  
Alveolar Type ◽  
Type I ◽  
Extrinsic Factors ◽  
Lung Epithelial

AbstractLate relapse of disseminated cancer cells is a common feature of some types of tumors. Several intrinsic and extrinsic factors have been shown to affect reawakening of disseminated dormant cancer cells (DDCCs); however, the signals and processes sustaining survival of DDCCs in a foreign environment are still poorly understood. We have recently shown that crosstalk with lung epithelial cells promotes persistence of DDCCs from estrogen receptor positive (ER+) breast tumors. Here we show that TFEB-lysosomal axis is activated in DDCCs and that it is modulated by the pro-survival ephrin receptor EphB6. TFEB lysosomal direct targets are enriched in DDCCs in vivo and correlate with relapse in ER+ breast cancer patients. Direct contact of DDCCs with alveolar type I-like lung epithelial cells drives lysosomal accumulation and EphB6 induction. EphB6 contributes to TFEB transcriptional activity and lysosome formation in DDCCs in vitro and in vivo, and supports survival of DDCCs in coculture and in vivo. Furthermore, signaling from EphB6 promotes the proliferative response of surrounding lung parenchymal cells in vivo.

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