Allelic depletion of grem1 attenuates diabetic kidney disease.
OBJECTIVE
Gremlin (grem1) is an antagonist of the bone morphogenetic protein family that plays a key role in limb bud development and kidney formation. There is a growing appreciation that altered grem1 expression may regulate the homeostatic constraints on damage responses in diseases such as diabetic nephropathy.


METHODS
Here we explored whether knockout mice heterozygous for grem1 gene deletion (grem1(+/-)) exhibit protection from the progression of diabetic kidney disease in a streptozotocin-induced model of type 1 diabetes.


RESULTS
A marked elevation in grem1 expression was detected in the kidneys and particularly in kidney tubules of diabetic wild-type mice compared with those of littermate controls. In contrast, diabetic grem1(+/-) mice displayed a significant attenuation in grem1 expression at 6 months of diabetes compared with that in age- and sex-matched wild-type controls. Whereas the onset and induction of diabetes were similar between grem1(+/-) and wild-type mice, several indicators of diabetes-associated kidney damage such as increased glomerular basement membrane thickening and microalbuminuria were attenuated in grem1(+/-) mice compared with those in wild-type controls. Markers of renal damage such as fibronectin and connective tissue growth factor were elevated in diabetic wild-type but not in grem1(+/-) kidneys. Levels of pSmad1/5/8 decreased in wild-type but not in grem1(+/-) diabetic kidneys, suggesting that bone morphogenetic protein signaling may be maintained in the absence of grem1.


CONCLUSIONS
These data identify grem1 as a potential modifier of renal injury in the context of diabetic kidney disease.
Roxburgh
Sarah A
SA
University College Dublin Diabetes Research Centre, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland.
Kattla
Jayesh J
JJ
Curran
Simon P
SP
O'Meara
Yvonne M
YM
Pollock
Carol A
CA
Goldschmeding
Roel
R
Godson
Catherine
C
Martin
Finian
F
Brazil
Derek P
DP
D000419:Albuminuria; D000818:Animals; D003404:Creatinine / Q000097:blood / Q000652:urine; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000473:pathology*; D003928:Diabetic Nephropathies / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D017353:Gene Deletion; D006442:Glycated Hemoglobin / Q000378:metabolism; D006706:Homeostasis; D036341:Intercellular Signaling Peptides and Proteins / Q000172:deficiency* / Q000235:genetics; D008055:Lipids / Q000097:blood; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D016207:Cytokines
D003404:Creatinine; D006442:Glycated Hemoglobin; D036341:Intercellular Signaling Peptides and Proteins; D008055:Lipids; C113178:Grem1 protein, mouse; D016207:Cytokines