Abstract
The relationship between the turnover of inositol phospholipids (Ptdlns) and the growth and differentiation of normal murine keratinocytes in culture was studied. Addition of myo-[U-14C] inositol to freshly plated cells resulted in a linear incorporation of radiolabel into the inositol phospholipids of the proliferating basal cells in culture during the initial 36 h, after which time the rate of radiolabel incorporation into the cells declined. The decrease in the incorporation of the radiolabel into the Ptdlns, particularly the more highly phosphorylated Ptdlns-4P and PtdIns4,5P2, correlated with the marked hydrolysis of these polyphosphoinositides and the rapid hydrolytic release of the inositol phosphates (InsP2 and InsP3). The transient accumulation of the InsPs correlated with the onset of differentiation of these cells. To ascertain whether the above observations of keratinocytes that were undergoing normal proliferative and differentiating phases in culture are consistent with the more synchronized populations of proliferative and differentiating cells, we investigated the turnover of Ptdlns in a Ca2+-regulated system of homogenous populations of proliferating mouse keratinocytes in 0.09 mM Ca2+, and a differentiating population in 1.8 mM Ca2+. Our data from system revealed rapid hydrolysis of the Ptdlns in the prelabeled low-Ca2+ proliferating cells immediately after a switch from the low to normal extracellular Ca2+ medium. Associated with this hydrolysis was the rapid and transient accumulation of the InsPs (maximum of 60 sec). The hydrolysis of the Ptdlns and the accumulation of the InsP3 were not observed when the prelabeled proliferating cells were switched from a low to a low extracellular Ca2+ medium. These results suggest that the rapid hydrolysis of the Ptdlns, particularly PtdIns4,5P2, which was accompanied by the hydrolytic release of InsP3, could be the initiating signal to program proliferating keratinocytes into differentiation.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 37-43 |
| Number of pages | 7 |
| Journal | Journal of Investigative Dermatology |
| Volume | 90 |
| Issue number | 1 |
| State | Published - Jan 1988 |
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Turnover of inositol phospholipids in cultured murine keratinocytes : Possible involvement of inositol triphosphate in cellular differentiation. / Tang, Wilson; Ziboh, Vincent A.; Isseroff, Roslyn Rivkah; Martinez, Deborah.
In: Journal of Investigative Dermatology, Vol. 90, No. 1, 01.1988, p. 37-43.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Turnover of inositol phospholipids in cultured murine keratinocytes
T2 - Possible involvement of inositol triphosphate in cellular differentiation
AU - Tang, Wilson
AU - Ziboh, Vincent A.
AU - Isseroff, Roslyn Rivkah
AU - Martinez, Deborah
PY - 1988/1
Y1 - 1988/1
N2 - The relationship between the turnover of inositol phospholipids (Ptdlns) and the growth and differentiation of normal murine keratinocytes in culture was studied. Addition of myo-[U-14C] inositol to freshly plated cells resulted in a linear incorporation of radiolabel into the inositol phospholipids of the proliferating basal cells in culture during the initial 36 h, after which time the rate of radiolabel incorporation into the cells declined. The decrease in the incorporation of the radiolabel into the Ptdlns, particularly the more highly phosphorylated Ptdlns-4P and PtdIns4,5P2, correlated with the marked hydrolysis of these polyphosphoinositides and the rapid hydrolytic release of the inositol phosphates (InsP2 and InsP3). The transient accumulation of the InsPs correlated with the onset of differentiation of these cells. To ascertain whether the above observations of keratinocytes that were undergoing normal proliferative and differentiating phases in culture are consistent with the more synchronized populations of proliferative and differentiating cells, we investigated the turnover of Ptdlns in a Ca2+-regulated system of homogenous populations of proliferating mouse keratinocytes in 0.09 mM Ca2+, and a differentiating population in 1.8 mM Ca2+. Our data from system revealed rapid hydrolysis of the Ptdlns in the prelabeled low-Ca2+ proliferating cells immediately after a switch from the low to normal extracellular Ca2+ medium. Associated with this hydrolysis was the rapid and transient accumulation of the InsPs (maximum of 60 sec). The hydrolysis of the Ptdlns and the accumulation of the InsP3 were not observed when the prelabeled proliferating cells were switched from a low to a low extracellular Ca2+ medium. These results suggest that the rapid hydrolysis of the Ptdlns, particularly PtdIns4,5P2, which was accompanied by the hydrolytic release of InsP3, could be the initiating signal to program proliferating keratinocytes into differentiation.
AB - The relationship between the turnover of inositol phospholipids (Ptdlns) and the growth and differentiation of normal murine keratinocytes in culture was studied. Addition of myo-[U-14C] inositol to freshly plated cells resulted in a linear incorporation of radiolabel into the inositol phospholipids of the proliferating basal cells in culture during the initial 36 h, after which time the rate of radiolabel incorporation into the cells declined. The decrease in the incorporation of the radiolabel into the Ptdlns, particularly the more highly phosphorylated Ptdlns-4P and PtdIns4,5P2, correlated with the marked hydrolysis of these polyphosphoinositides and the rapid hydrolytic release of the inositol phosphates (InsP2 and InsP3). The transient accumulation of the InsPs correlated with the onset of differentiation of these cells. To ascertain whether the above observations of keratinocytes that were undergoing normal proliferative and differentiating phases in culture are consistent with the more synchronized populations of proliferative and differentiating cells, we investigated the turnover of Ptdlns in a Ca2+-regulated system of homogenous populations of proliferating mouse keratinocytes in 0.09 mM Ca2+, and a differentiating population in 1.8 mM Ca2+. Our data from system revealed rapid hydrolysis of the Ptdlns in the prelabeled low-Ca2+ proliferating cells immediately after a switch from the low to normal extracellular Ca2+ medium. Associated with this hydrolysis was the rapid and transient accumulation of the InsPs (maximum of 60 sec). The hydrolysis of the Ptdlns and the accumulation of the InsP3 were not observed when the prelabeled proliferating cells were switched from a low to a low extracellular Ca2+ medium. These results suggest that the rapid hydrolysis of the Ptdlns, particularly PtdIns4,5P2, which was accompanied by the hydrolytic release of InsP3, could be the initiating signal to program proliferating keratinocytes into differentiation.
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M3 - Article
VL - 90
SP - 37
EP - 43
JO - Journal of Investigative Dermatology
JF - Journal of Investigative Dermatology
SN - 0022-202X
IS - 1
ER -