scholarly journals The posttranslational processing of sucrase-isomaltase in HT-29 cells is a function of their state of enterocytic differentiation.

1987 ◽  
Vol 104 (5) ◽  
pp. 1199-1205 ◽  
Author(s):  
G Trugnan ◽  
M Rousset ◽  
I Chantret ◽  
A Barbat ◽  
A Zweibaum

The biosynthesis of sucrase-isomaltase was compared in enterocyte-like differentiated (i.e., grown in the absence of glucose) and undifferentiated (i.e., grown in the presence of glucose) HT-29 cells. Unlike differentiated cells, in which the enzyme is easily detectable and active, undifferentiated cells display almost no enzyme activity and the protein cannot be detected by means of cell surface immunofluorescence or immunodetection in membrane-enriched fractions or cell homogenates. Pulse experiments with L-[35S]-methionine show that the enzyme is, however, synthesized in these undifferentiated cells. As compared with the corresponding molecular forms in differentiated cells, the high-mannose form of the enzyme in undifferentiated cells is similarly synthesized and has the same apparent Mr. However, its complex form is less labeled and has a lower apparent Mr. Pulse-chase experiments with L-[35S]methionine show that, although the enzyme is synthesized to the same extent in both situations, the high-mannose and complex forms are rapidly degraded in undifferentiated cells, with an apparent half-life of 6 h, in contrast to differentiated cells in which the enzyme is stable for at least 48 h. A comparison of the processing of the enzyme in both situations shows that the conversion of the high-mannose to the complex form is markedly decreased in undifferentiated cells. These results indicate that the absence of sucrase-isomaltase expression in undifferentiated cells is not the consequence of an absence of biosynthesis but rather the result of both an impaired glycosylation and a rapid degradation of the enzyme.

1995 ◽  
Vol 309 (2) ◽  
pp. 521-527 ◽  
Author(s):  
J J Houri ◽  
E Ogier-Denis ◽  
D De Stefanis ◽  
C Bauvy ◽  
F M Baccino ◽  
...  

Our previous results have demonstrated that, in undifferentiated human colon cancer HT-29 cells, a pool of glycoproteins bearing high-mannose oligosaccharides rapidly escapes the exocytic pathway to be degraded in the lysosomal compartment [Trugnan, Ogier-Denis, Sapin, Darmoul, Bauvy, Aubery and Codogno (1991) J. Biol. Chem. 266, 20849-20855]. We report here on the mechanism that governs this degradative pathway. Using pulse-chase experiments in combination with subcellular fractionation, we have observed that the sequestration of high-mannose glycoproteins in lysosomes was impaired by drugs which interfere with the autophagic-lysosomal pathway. The accumulation of high-mannose glycoproteins in the lysosomal fraction was shown to be part of the general autophagic pathway constitutively expressed in undifferentiated cells, as independently measured by the sequestration of the cytosolic enzyme lactate dehydrogenase and electroloaded raffinose. Furthermore, when HT-29 cells were cultured under differentiation-permissive conditions, the decreased accumulation of high-mannose glycoproteins in the lysosomal compartment was correlated with the decrease in autophagy.


2021 ◽  
Vol 11 (9) ◽  
pp. 3729
Author(s):  
Katarzyna Balon ◽  
Benita Wiatrak

Models based on cell cultures have become a useful tool in modern scientific research. Since primary cell lines are difficult to obtain and handle, neoplasm-derived lines like PC12 and THP-1 offer a cheap and flexible solution for neurobiological studies but require prior differentiation to serve as a neuronal or microglia model. PC12 cells constitute a suitable research model only after differentiation by incubation with nerve growth factor (NGF) and THP-1 cells after administering a differentiation factor such as phorbol 12-myristate-13-acetate (PMA). Still, quite often, studies are performed on these cancer cells without differentiation. The study aimed to assess the impact of PC12 or THP-1 cell differentiation on sensitivity to harmful factors such as Aβ25-35 (0.001–5 µM) (considered as one of the major detrimental factors in the pathophysiology of Alzheimer’s disease) or lipopolysaccharide (1–100 µM) (LPS; a pro-inflammatory factor of bacterial origin). Results showed that in most of the tests performed, the response of PC12 and THP-1 cells induced to differentiation varied significantly from the effect in undifferentiated cells. In general, differentiated cells showed greater sensitivity to harmful factors in terms of metabolic activity and DNA damage, while in the case of the free radicals, the results were heterogeneous. Obtained data emphasize the importance of proper differentiation of cell lines of neoplastic origin in neurobiological research and standardization of cell culture handling protocols to ensure reliable results.


1986 ◽  
Vol 6 (11) ◽  
pp. 3920-3927
Author(s):  
K Ariizumi ◽  
H Ariga

A small circular DNA was found extrachromosomally in a clone of F9 embryonal carcinoma (EC) cells at high copy numbers per cell. The DNA was cloned in plasmid pUC19. Restriction endonuclease analyses of the DNA indicated that the DNA (fPyF9) was a mutant of polyomavirus (Py) DNA and had a mutation in a noncoding regulatory region. There have been many reports on the isolation of Py mutants capable of replication in undifferentiated cells. However, fPyF9 was different from other Py mutants in the following aspects: it was harbored stably as a free copy at 1 X 10(4) to 5 X 10(4) copies per cell in EC cells; it replicated in undifferentiated cells better than in differentiated cells; it was extremely rearranged in the sequences of the enhancer B domain; and it carried in the enhancer B domain three copies of an exogenous sequence which does not exist in Py strain A2. From these observations, we propose a new class of Py EC mutant which has an autonomous state similar to that of plasmid and small circular DNA in host cells.


2018 ◽  
Author(s):  
Víctor Alejandro Zapata Trejo

The epigenome regulates the gene expression of all differentiated cells and indicates which specific genes must be transcribed. It is argued that the expression factors that act on specific genes of the somatic cell involved in a behavior also act on the transcription of the same genes in the most undifferentiated cells of the germ line. It is proposed how a probabilistic view of the random mutation can explain the evolution of the phenotypes and integrate all the evidence pointing to a joint evolution with the environment.


2018 ◽  
Author(s):  
Víctor Alejandro Zapata Trejo

The epigenome regulates the gene expression of all differentiated cells and indicates which specific genes must be transcribed. It is argued that the expression factors that act on specific genes of the somatic cell involved in a behavior also act on the transcription of the same genes in the most undifferentiated cells of the germ line. It is proposed how a probabilistic view of the random mutation can explain the evolution of the phenotypes and integrate all the evidence pointing to a conjunct evolution with the environment.


2018 ◽  
Author(s):  
Víctor A Zapata Trejo

The epigenome regulates the gene expression of all differentiated cells and indicates which specific genes must be transcribed. It is argued that the expression factors that act in specific genes of the somatic cells involved in a behavior also act in the partial transcription of the same genes in the most undifferentiated cells of the germ line. It is proposed how a probabilistic view of the random mutation can explain the evolution of the phenotypes and integrate all the evidence pointing to a conjunct evolution with the environment.


1985 ◽  
Vol 122 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Alain Zweibaum ◽  
Mo�se Pinto ◽  
Guillemette Chevalier ◽  
Elisabeth Dussaulx ◽  
Nicole Triadou ◽  
...  

1995 ◽  
Vol 24 (3) ◽  
pp. 315-348 ◽  
Author(s):  
Marilyn R. Whalen

ABSTRACTChildren's play activities are widely perceived as developing from primitive to increasingly complex forms of social organization, as children mature and acquire interactional competency. Research following this traditional, developmentally oriented approach postulates that sports and games with rules are the most advanced and complex form of play activity; activities involving fantasy and pretend-play are viewed in comparison as considerably less complex. This article argues that fantasy play encounters exhibit complex features in their own right, and that long-held distinctions between higher-order games and fantasy play are conceptually overdrawn. The argument is grounded in a conversation analytic study of the play activities of a cross-sex, mixed-age neighborhood play group. This analysis focuses on the endogenous social organization of a fantasy play encounter. (Conversation analysis, children's play, socialization, social psychology)


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