Implication of acyl chain of diacylglycerols in activation of different isoforms of protein kinase C

Abstract

We synthesized diacylglycerols (DAGs) containing omega-6 or omega-3 polyunsaturated fatty acids [i.e., 1-stearoyl-2-arachidonoyl-sn-glycerol (SAG), 1-stearoyl-2-docosahexaenoyl-sn-glycerol (SDG), and 1-stearoyl-2-eicosapentaenoyl-sn-glycerol (SEG)] and assessed their efficiency on activation of conventional (alpha, beta I, gamma) and novel (epsilon, delta) protein kinase C (PKC). SAG exerted significantly higher stimulatory effects than SDG and SEG on activation of PKC alpha and PKC delta. Activation of PKC beta I by SEG and SDG was higher than that by SAG. Activation of PKC gamma did not differ significantly among DAG molecular species. Addition of SAG to assays containing SEG and SDG exerted additive effects on activation of alpha and epsilon, but not on beta I and gamma, isoforms of PKC. SDG- and SEG-induced activation of PKC delta was significantly curtailed by the addition of SAG. Three DAG species significantly curtailed the PMA-induced activation of beta Iota, gamma, and delta, but not of alpha and epsilon, isoforms of PKC. Our study demonstrates for the first time that in vitro activation of different PKC isoenzymes vary in response to different DAG species, and one can envisage that this differential regulation may be responsible for their in vivo effects on target organs.

Role of diacylglycerol activation of PKCθ in lipid-induced muscle insulin resistance in humans

“…These data are consistent with previous studies in rodents that have shown that lipid infusion leads to a transient increase in intramyocellular DAG content, PKCθ activation, and muscle insulin resistance (10,11). In vitro activation of different nPKC isoforms vary in response to different DAG species with different time courses and competitive effects of specific DAG species (29). This might explain the difference between the present and previous findings of increased activity of membrane-associated PKCβII and PKCδ isoforms but unchanged PKCθ, PKCe, and PKCζ after a 6-h lipid infusion combined with a hyperinsulinemic-euglycemic clamp (15).…”

Diacylglycerols Containing Omega 3 and Omega 6 Fatty Acids Bind to RasGRP and Modulate MAP Kinase Activation

“…On the other hand, EPA incorporated into DAG has been found to reduce vascular complications associated with diabetes (22). In the same way, we have recently demonstrated that different isoforms of conventional PKCs (␣, ␤I, and ␥) and novel PKCs (⑀ and ␦) differ in their response to DAGs containing omega 6 or omega 3 PUFAs in a cell-free system (23). As far as the modulation of RasGRP by DAG is concerned, to our knowledge, a few studies are available.…”

“…Synthesis of SAG, SDG, and SEG-SAG, SDG, and SEG were obtained by the action of phospholipase C from Bacillus cereus on 1-stearoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (1-stearoyl-2-arachidonoyl-PC), 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (stearoyl-2-docosahexaenoyl-PC) and 1-stearoyl-2-eicosapentaenoyl-PC, respectively, as described previously (23). Briefly, DAGs after their synthesis were purified using straight-phase HPLC on a 30 cm porasil column (Millipore, Saint-Quentin, France) and eluted isocratically with hexane/isopropyl alcohol, 100:1 (v/v).…”

Dietary long-chainn-3 fatty acids modify blood and cardiac phospholipids and reduce protein kinase-C-δ and protein kinase-C-ε translocation

“…In particular, the PUFA at the sn-2 position of DAG selectively affect the activity of DAG-activated PKC 9,10 .…”