Regulation of synthesis of lactosylceramide in normal and tumor proximal tubular cells

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Abstract

We have measured the binding and degradation of low-density lipoprotein (LDL) and LDL-mediated effects on cholesteryl ester (CE) synthesis in cultured normal and tumor proximal tubular (PT) cells. The effects of LDL on the regulation of glycosphingolipid metabolism in cells was pursued employing radioactive precursors, e.g., [3H]serine, and [3H]glucose and by measuring the activity of UDP-galactose:glucosylceramide:B1-4 galactosyltransferase (GalT-2). In normal PT cells, there was a saturable and displaceable binding and degradation of 125I-LDL and a LDL mediated 14-fold stimulation of cholesteryl ester (CE) synthesis. This was accompanied by a suppression (70-80%) of incorporation of [3H]glucose and [3H]serine into GlcCer, LacCer, GbOse3Cer and GbOse4Cer and suppression (70-80%) of GalT-2 activity. In tumor PT cells, displaceable binding and degradation of 125I-LDL was not observed and LDL failed to stimulate CE synthesis. In such cells, LDL exerted a concentration-dependent stimulation of [3H]glucose and [3H]serine incorporation into GSL. Maximum stimulation (250%) of GalT-2 activity in tumor PT cells occurred with 25 μg LDL/ml medium. We conclude that LDL taken up via receptor mediated pathway decreases GaIT-2 activity in normal PT cells. In contrast, LDL not taken up via the LDL receptor pathway in tumor PT cells failed to suppress the incorporation of [3H]glucose and [3H]serine into glycosphingolipids and GalT-2 activity leading to a stimulation of lactosylceramide synthesis.

Original languageEnglish (US)
Pages (from-to)339-344
Number of pages6
JournalBiochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
Volume1167
Issue number3
DOIs
StatePublished - Apr 23 1993

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LDL Lipoproteins
Tumors
Neoplasms
Serine
Cholesterol Esters
Glucose
Glycosphingolipids
Degradation
CDw17 antigen
Uridine Diphosphate Galactose
Glucosylceramides
Galactosyltransferases
LDL Receptors
Metabolism
Cell Count
glucosylceramide beta-1-4-galactosyltransferase

Keywords

  • (Human)
  • Galactosyltransferase, B1-4
  • Glycosphingolipid
  • Kidney
  • Lactosylceramide
  • LDL receptor
  • Tubular tumor cell

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Endocrinology

Cite this

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title = "Regulation of synthesis of lactosylceramide in normal and tumor proximal tubular cells",
abstract = "We have measured the binding and degradation of low-density lipoprotein (LDL) and LDL-mediated effects on cholesteryl ester (CE) synthesis in cultured normal and tumor proximal tubular (PT) cells. The effects of LDL on the regulation of glycosphingolipid metabolism in cells was pursued employing radioactive precursors, e.g., [3H]serine, and [3H]glucose and by measuring the activity of UDP-galactose:glucosylceramide:B1-4 galactosyltransferase (GalT-2). In normal PT cells, there was a saturable and displaceable binding and degradation of 125I-LDL and a LDL mediated 14-fold stimulation of cholesteryl ester (CE) synthesis. This was accompanied by a suppression (70-80{\%}) of incorporation of [3H]glucose and [3H]serine into GlcCer, LacCer, GbOse3Cer and GbOse4Cer and suppression (70-80{\%}) of GalT-2 activity. In tumor PT cells, displaceable binding and degradation of 125I-LDL was not observed and LDL failed to stimulate CE synthesis. In such cells, LDL exerted a concentration-dependent stimulation of [3H]glucose and [3H]serine incorporation into GSL. Maximum stimulation (250{\%}) of GalT-2 activity in tumor PT cells occurred with 25 μg LDL/ml medium. We conclude that LDL taken up via receptor mediated pathway decreases GaIT-2 activity in normal PT cells. In contrast, LDL not taken up via the LDL receptor pathway in tumor PT cells failed to suppress the incorporation of [3H]glucose and [3H]serine into glycosphingolipids and GalT-2 activity leading to a stimulation of lactosylceramide synthesis.",
keywords = "(Human), Galactosyltransferase, B1-4, Glycosphingolipid, Kidney, Lactosylceramide, LDL receptor, Tubular tumor cell",
author = "Chatterjee, {Subroto B}",
year = "1993",
month = "4",
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doi = "10.1016/0005-2760(93)90238-5",
language = "English (US)",
volume = "1167",
pages = "339--344",
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TY - JOUR

T1 - Regulation of synthesis of lactosylceramide in normal and tumor proximal tubular cells

AU - Chatterjee, Subroto B

PY - 1993/4/23

Y1 - 1993/4/23

N2 - We have measured the binding and degradation of low-density lipoprotein (LDL) and LDL-mediated effects on cholesteryl ester (CE) synthesis in cultured normal and tumor proximal tubular (PT) cells. The effects of LDL on the regulation of glycosphingolipid metabolism in cells was pursued employing radioactive precursors, e.g., [3H]serine, and [3H]glucose and by measuring the activity of UDP-galactose:glucosylceramide:B1-4 galactosyltransferase (GalT-2). In normal PT cells, there was a saturable and displaceable binding and degradation of 125I-LDL and a LDL mediated 14-fold stimulation of cholesteryl ester (CE) synthesis. This was accompanied by a suppression (70-80%) of incorporation of [3H]glucose and [3H]serine into GlcCer, LacCer, GbOse3Cer and GbOse4Cer and suppression (70-80%) of GalT-2 activity. In tumor PT cells, displaceable binding and degradation of 125I-LDL was not observed and LDL failed to stimulate CE synthesis. In such cells, LDL exerted a concentration-dependent stimulation of [3H]glucose and [3H]serine incorporation into GSL. Maximum stimulation (250%) of GalT-2 activity in tumor PT cells occurred with 25 μg LDL/ml medium. We conclude that LDL taken up via receptor mediated pathway decreases GaIT-2 activity in normal PT cells. In contrast, LDL not taken up via the LDL receptor pathway in tumor PT cells failed to suppress the incorporation of [3H]glucose and [3H]serine into glycosphingolipids and GalT-2 activity leading to a stimulation of lactosylceramide synthesis.

AB - We have measured the binding and degradation of low-density lipoprotein (LDL) and LDL-mediated effects on cholesteryl ester (CE) synthesis in cultured normal and tumor proximal tubular (PT) cells. The effects of LDL on the regulation of glycosphingolipid metabolism in cells was pursued employing radioactive precursors, e.g., [3H]serine, and [3H]glucose and by measuring the activity of UDP-galactose:glucosylceramide:B1-4 galactosyltransferase (GalT-2). In normal PT cells, there was a saturable and displaceable binding and degradation of 125I-LDL and a LDL mediated 14-fold stimulation of cholesteryl ester (CE) synthesis. This was accompanied by a suppression (70-80%) of incorporation of [3H]glucose and [3H]serine into GlcCer, LacCer, GbOse3Cer and GbOse4Cer and suppression (70-80%) of GalT-2 activity. In tumor PT cells, displaceable binding and degradation of 125I-LDL was not observed and LDL failed to stimulate CE synthesis. In such cells, LDL exerted a concentration-dependent stimulation of [3H]glucose and [3H]serine incorporation into GSL. Maximum stimulation (250%) of GalT-2 activity in tumor PT cells occurred with 25 μg LDL/ml medium. We conclude that LDL taken up via receptor mediated pathway decreases GaIT-2 activity in normal PT cells. In contrast, LDL not taken up via the LDL receptor pathway in tumor PT cells failed to suppress the incorporation of [3H]glucose and [3H]serine into glycosphingolipids and GalT-2 activity leading to a stimulation of lactosylceramide synthesis.

KW - (Human)

KW - Galactosyltransferase, B1-4

KW - Glycosphingolipid

KW - Kidney

KW - Lactosylceramide

KW - LDL receptor

KW - Tubular tumor cell

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U2 - 10.1016/0005-2760(93)90238-5

DO - 10.1016/0005-2760(93)90238-5

M3 - Article

C2 - 8481397

AN - SCOPUS:0027294735

VL - 1167

SP - 339

EP - 344

JO - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids

JF - Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids

SN - 1388-1981

IS - 3

ER -