Energy metabolism in the involuting mammary gland.
A strong and coordinated upregulation of the glycolytic, glutaminolytic and pentose phosphate pathway enzymes occurs during the onset of lactation in the normal mouse mammary gland. Induction of apoptosis by removing the pups led to an inactivation of the same enzymes with different time courses. While the ATP-consuming glycolytic 6-phosphofructo 1-kinase and mitochondrial bound hexokinase still remained high on days one and two of involution, the ATP-regenerating pyruvate kinase was immediately reduced. The enzymes of the pentose phosphate and glutaminolytic pathway were inactivated on the first two days of involution. In accordance with such an inactivation of the enzymes ATP, GTP, UTP, ADP, NAD NADH and lactate concentrations decreased. The synthetic product of UTP, UDP-N-acetylglucosamine, increased. AMP was found in the milk, not in the epithelial cells. The inactivation of the enzymes was caused by partial proteolysis or by a loss of the intact proteins from the cytosol without signs of proteolysis.
Mazurek
S
S
Institute for Biochemistry & Endocrinology, Veterinary Faculty, University of Giessen, Germany. Sybille.Mazurek@vetmed.uni-giessen.de
Weisse
G
G
Wüst
G
G
Schäfer-Schwebel
A
A
Eigenbrodt
E
E
Friis
R R
RR
D000818:Animals; D002455:Cell Division / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology / Q000201:enzymology; D005260:Female; D005948:Glucose Dehydrogenases / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D006019:Glycolysis / Q000502:physiology; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007774:Lactation / Q000502:physiology*; D008291:Malate Dehydrogenase / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000166:cytology / Q000201:enzymology*; D051379:Mice; D008928:Mitochondria / Q000201:enzymology; D009712:Nucleotides, Cyclic / Q000378:metabolism; D010427:Pentose Phosphate Pathway / Q000502:physiology; D010734:Phosphogluconate Dehydrogenase / Q000378:metabolism; D010766:Phosphorylation; D011247:Pregnancy; D011770:Pyruvate Kinase / Q000378:metabolism; D014886:Weaning
D009712:Nucleotides, Cyclic; D005948:Glucose Dehydrogenases; D007770:L-Lactate Dehydrogenase; D008291:Malate Dehydrogenase; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+); D010734:Phosphogluconate Dehydrogenase; C034544:D-malate dehydrogenase (decarboxylating); D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D011770:Pyruvate Kinase