Glucose metabolism in transdifferentiating and glucose-blocked cultures of chick embryo neuroretinal cells: an inverse relationship between glycogen and δ-crystallin accumulation

Karim, Shahid; Flor-Henry, Michel; Pomerai, David I. de

doi:10.1016/0045-6039(87)90411-8

Cited by 3 publications

(13 citation statements)

References 33 publications

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“…The former is encouraged by high-glucose and the latter by low-glucose media. In situ histochemical staining of high-glucose NR cultures suggests that both glycogen synthetase activity and glycogen deposits are co-localized mainly in G cells underlying clusters of neuron-like N cells (Karim et al, 1987). At first sight this accords with other evidence to the effect that the normal differentiation of Muller glia depends upon interactions with overlying neurons (Linser & Moscona, 1979, 1983).…”

Section: Introductionsupporting

confidence: 71%

“…Previous work (Karim et al, 1987) has demonstrated an inverse relationship between the levels of glycogen (a differentiated feature of retinal glial cells) and of 1-crystallin (a marker of lens conversion) in transdifferentiating cultures of chickembryo neuroretinal (NR) cells. Glycogen is accumulated in retinal glia (Miiller cells) both during normal differentiation in vivo (Kuwabara & Cogan, 1961;Macalh & Coimbra, 1970) and also in vitro during cell culture in the presence of high glucose concentrations (Karim et al, 1987). In total NR cultures, high ambient glucose levels also suppress transdifferentiation into lens (de , apparently by blocking transcription of the 8-crystallin locus (Carr & de Pomerai, 1985).…”

Section: Introductionmentioning

confidence: 99%

“…Our previous study (Karim et al, 1987) suggested that retinal G cells in culture might choose between normal differentiation towards the Miiller-glial phenotype and a 'foreign' transdifferentiation pathway leading towards lens/pigmented-epithelium phenotypes. The former is encouraged by high-glucose and the latter by low-glucose media.…”

Section: Introductionmentioning

confidence: 99%

“…FHG containing 10-M-forskolin (Rousset et al, 1985). Simi-larly, ouabain was added to 10-7 M in FHGO medium (Karim et al, 1987). The protein content of all cultures was determined by the method of Lowry et al (1951), with BSA as standard.…”

Section: Introductionmentioning

confidence: 99%

“…(ii) Measurement of glycogen content. The glycogen content of retinal cultures was determined as described previously (Rousset et al, 1981;Karim et al, 1987) by using the anthrone reagent. These assays were calibrated using known amounts of glucose alongside the test solutions containing glycogen.…”

Section: Introductionmentioning

confidence: 99%

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A choice between glycogen and δ-crystallin accumulation is made in glial cells and not influenced by overlying neurons

Karim¹,

Pomerai

1992

Biochemical Journal

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Chick-embryo neuroretinal cells convert extensively into lens under low-glucose conditions, but this transdifferentiation process is blocked by high-glucose media. We have previously observed an inverse relationship between the levels of glycogen (a marker of normal retinoglial differentiation) and of delta-crystallin (a lens marker) in such cultures. However, most of the glycogen accumulated under high-glucose conditions is apparently localized in those glial (G) cells underlying clusters of neurons (N cells). We here show that glial-enriched cultures (largely depleted of N cells) both accumulate glycogen and fail to transdifferentiate in high-glucose media. Moreover, glycogen localization in groups of glial cells is unaffected by the absence of N cells. Thus the choice between normal and foreign differentiation pathways is made autonomously within the retinoglial-cell population and is not influenced significantly by the presence or absence of N cells.

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Section: Introductionsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A choice between glycogen and δ-crystallin accumulation is made in glial cells and not influenced by overlying neurons

Karim¹,

Pomerai

1992

Biochemical Journal

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Cellular src Gene Expression Associated with Lentoidogenesis in Transdifferentiating Cultures.

1988

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We have shown (9) that elevated pp60c–src kinase activity accompanies the transdifferentiation of chick embryo neuroretinal (NR) cells into lens in vitro; moreover, most immunologically‐detectable pp60c–src protein is confined to lentoid bodies in permissive cultures (FH; 6). By contrast, pp60c–src expression is low in non‐permissive cultures where lentoid formation is blocked by high glucose (FHG; 6) or medium 199 (11). We now extend these findings in several respects. Firstly, glial‐enriched cultures in both FH and FHG media form small but sparse lentoid bodies at around 20 days, accompanied by increases in both δ crystallin and pp60c–src expression. In later FHG cultures, these lentoids increase neither in number/size nor in δ/pp60c–src expression, in contrast to permissive (FH) cultures. Thus the high glucose block on transdifferentiation is only partly mediated by neuronal influences (19). Secondly, transdifferentiating cultures of tapetal cells show higher levels of pp60c–src relative to redifferentiated or dedifferentiated (16, 17) cultures of these cells. Thirdly, we find no evidence that c‐src oncogene expression directly signals transdifferentiation. Thus v‐src expression in RSV‐transformed NR cells inhibits δ crystallin accumulation (29; this study), while a c‐src‐substituted RSV variant has little effect on NR transdifferentiation. Late cultures of NR cells in medium 199 fail to accumulate pp60c–src protein or c‐src transcripts, even though previous studies (2) showed that δ crystallin transcripts are localised within the nuclei of many cells in such cultures.

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Effects of Pluronic F-68 on 2-Deoxyglucose Uptake and Amino Acid Incorporation into Chick Embryonic Fibroblasts in Culture

Cawrse

Pomerai

Lowe

1990

Journal of Pharmacy and Pharmacology

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Glucose metabolism in transdifferentiating and glucose-blocked cultures of chick embryo neuroretinal cells: an inverse relationship between glycogen and δ-crystallin accumulation

Cited by 3 publications

References 33 publications

A choice between glycogen and δ-crystallin accumulation is made in glial cells and not influenced by overlying neurons

A choice between glycogen and δ-crystallin accumulation is made in glial cells and not influenced by overlying neurons

Cellular src Gene Expression Associated with Lentoidogenesis in Transdifferentiating Cultures.

Effects of Pluronic F-68 on 2-Deoxyglucose Uptake and Amino Acid Incorporation into Chick Embryonic Fibroblasts in Culture

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