Diacylglycerol kinase zeta in hypothalamus interacts with long form leptin receptor. Relation to dietary fat and body weight regulation.
Leptin and its long form receptor, Ob-Rb, in hypothalamic nuclei play a key role in regulating energy balance. The mutation of Ob-Rb into one of its natural variants, Ob-Ra, results in severe obesity in rodents. We demonstrate here that diacylglycerol kinase zeta (DGKzeta) interacts, via its ankyrin repeats, with the cytoplasmic portion of Ob-Rb in yeast two-hybrid systems, in protein precipitation experiments in vitro and in vivo. It does not interact, however, with the short form, Ob-Ra, which mediates the entry of leptin into the brain. Furthermore, we show by in situ hybridization that DGKzeta is expressed in neurons of hypothalamic nuclei known to synthesize Ob-Rb and to participate in energy homeostasis. The mutant ob-/ob- and db-/db- mice exhibit increased hypothalamic DGKzeta mRNA level compared with their wild-type controls, suggesting a role for the leptin/OB-Rb system in regulating DGKzeta expression. Further experiments show that hypothalamic DGKzeta mRNA level is stimulated by the consumption of a high-fat diet. In addition, DGKzeta mRNA is statistically significantly lower in rats and inbred mice that become obese on a high-fat diet compared with their lean counterparts. In fact, it is strongly, negatively correlated with both body fat and circulating levels of leptin. Taken together, our evidence suggests that DGKzeta constitutes a downstream component of the leptin signaling pathway and that reduced hypothalamic DGKzeta mRNA, and possibly activity, is associated with obesity.
Liu
Z
Z
Rockefeller University, New York, New York 10021, USA.
Chang
G Q
GQ
Leibowitz
S F
SF
D000595:Amino Acid Sequence; D000818:Animals; D017089:Ankyrin Repeat; D001483:Base Sequence; D001665:Binding Sites; D001835:Body Weight / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism*; D019852:Diacylglycerol Kinase / Q000302:isolation & purification / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism; D004435:Eating; D004734:Energy Metabolism / Q000502:physiology; D007031:Hypothalamus / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; D014018:Tissue Distribution; D020798:Two-Hybrid System Techniques
D002352:Carrier Proteins; D004041:Dietary Fats; D007527:Isoenzymes; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin; C515447:leptin receptor, mouse; D019852:Diacylglycerol Kinase