Deletion of MK2 signalling in vivo inhibits small Hsp phosphorylation but not diabetic nephropathy.
It is supposed that some stress-induced heat shock proteins (Hsps) are regulated through e.g. stimulation of the p38MAPK/MK(MAPKAP)-2 signalling pathway. It has been postulated from in vitro experiments that phosphorylation of Hsp25(rodents)/Hsp27(human), the major phosphorylation substrate of MK2, is responsible for mesangial contractility and glomerular hyperfiltration in the diabetic kidney. To verify this hypothesis in vivo we studied the renal function of nondiabetic and streptozotocin (STZ)-induced, diabetic MK2(-/-) mice in comparison to wild-type (WT) control mice. Following 8 weeks of hyperglycaemia, light microscopy showed increased glomerulosclerosis and tubulointerstitial renal fibrosis in both diabetic study groups. Protein analysis demonstrated that Hsp25 phosphorylation is stimulated upon high-glucose condition but inhibited in the diabetic MK2(-/-) mice. However, we found the kidney-body weight ratio significantly increased in diabetic WT and MK2(-/-) mice. No difference regarding the increased expression of the extracellular matrix proteins and TGF-beta1 between both diabetic study groups was observed. Importantly, diabetic MK2(-/-) mice showed no protection against renal hyperfiltration in the diabetic state and the development of diabetic albuminuria. Although activation of p38MAPK has been previously shown in diabetes mellitus, our results indicate that blockade of the downstream MK2/Hsp25 signalling pathway does not interfere with the development of early diabetic nephropathy.
Park
Joon-Keun
JK
Department of Nephrology, Hannover Medical School, Hannover, Germany.
Ronkina
Natalia
N
Höft
Andreas
A
Prohl
Corinna
C
Menne
Jan
J
Gaestel
Matthias
M
Haller
Hermann
H
Meier
Matthias
M
D000704:Analysis of Variance; D000818:Animals; D003921:Diabetes Mellitus, Experimental; D003928:Diabetic Nephropathies / Q000235:genetics* / Q000473:pathology* / Q000503:physiopathology; D004195:Disease Models, Animal; D005919:Glomerular Filtration Rate; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D011336:Probability; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D011897:Random Allocation; D012016:Reference Values; D012680:Sensitivity and Specificity; D017384:Sequence Deletion / Q000502:physiology; D015398:Signal Transduction; D013311:Streptozocin; D000099190:MAP-Kinase-Activated Kinase 2
D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D013311:Streptozocin; D000099190:MAP-Kinase-Activated Kinase 2