ABSTRACT: Insulin-regulated aminopeptidase (IRAP) and the insulin-dependent glucose transporter GLUT4 colocalize in specific intracellular vesicles (that is, GLUT4 vesicles). These vesicles move slowly to the cell surface, but their translocation is markedly enhanced by insulin, resulting in higher glucose uptake. Previous studies of the insulin-mediated translocation of IRAP to the cell surface have been hampered by the laborious detection of IRAP at the cell surface. We aimed to develop a more direct and faster method to detect IRAP. To this end, we used model systems with well-characterized IRAP: CHO-K1 cells expressing endogenous IRAP and recombinant HEK293 cells expressing human IRAP. A more widespread application of the method was demonstrated by the use of 3T3-L1 adipocytes.
After stimulation of the cells with insulin, internalization of IRAP was inhibited by the addition of phenyl arsine oxide (PAO). Then, cell-surface IRAP was detected by the high-affinity binding of radiolabelled angiotensin (Ang) IV (either 125I or 3H).
We monitored the time- and concentration dependence of insulin-mediated translocation of IRAP in both cell lines and 3T3-L1 adipocytes. A plateau was reached between 6 and 8 min, and 10(-7) M insulin led to the highest amount of IRAP at the cell surface.
Based on the capacity of the IRAP apoenzyme to display high affinity for radiolabelled Ang IV and on the ability of PAO to inhibit IRAP internalization, we developed a more direct and faster method to measure insulin-mediated translocation of IRAP to the cell surface.
British Journal of Pharmacology 07/2008; 154(4):872-81. · 4.41 Impact Factor
ABSTRACT: Subcorneal pustular dermatosis (SPD) is a chronic recurrent pustular dermatosis of unknown etiology. Many treatments have been proposed, none of which has been uniformly successful.
Our purpose is to report a patient with SPD successfully treated by PUVA and to review the literature concerning phototherapy treatment of SPD.
A patient suffering from SPD resistant to diaminodiphenylsulphone (dapsone) responded well to a combination therapy consisting of dapsone and PUVA. He received 50 mg/day and 3 PUVA sessions a week. Photographs were taken at baseline and after 15 sessions.
The lesions were virtually cleared after 15 sessions. The patient remained free of lesions with a maintenance therapy of dapsone (50 mg/ day) and 1 PUVA session a week.
The therapeutic value of phototherapy for the treatment of SPD still has to be confirmed and could be a valuable alternative for treatment-resistant patients.
Dermatology 02/1999; 198(2):203-5. · 2.05 Impact Factor
Journal of the American Academy of Dermatology 11/1997; 37(4):653-5. · 3.99 Impact Factor