Enhanced expression of two discrete isoforms of matrix metalloproteinase-2 in experimental and human diabetic nephropathy.
BACKGROUND
We recently reported on the enhanced expression of two isoforms of matrix metalloproteinase-2 (MMP-2) in human renal transplantation delayed graft function. These consist of the conventional secreted, full length MMP-2 isoform (FL-MMP-2) and a novel intracellular N-Terminal Truncated isoform (NTT-MMP-2) generated by oxidative stress-mediated activation of an alternate promoter in the MMP-2 first intron. Here we evaluated the effect of hyperglycemia and diabetes mellitus on the in vitro and in vivo expression of the two MMP-2 isoforms.


METHODS
We quantified the abundance of the FL-MMP-2 and NTT-MMP-2 transcripts by qPCR in HK2 cells cultured in high glucose or 4-hydroxy-2-hexenal (HHE) and tested the effects of the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC). The streptozotocin (STZ) murine model of Type I diabetes mellitus and renal biopsies of human diabetic nephropathy were used in this study.


RESULTS
Both isoforms of MMP-2 in HK2 cells were upregulated by culture in high glucose or with HHE. PDTC treatment did not suppress high glucose-mediated FL-MMP-2 expression but potently inhibited NTT-MMP-2 expression. With STZ-treated mice, renal cortical expression of both isoforms was increased (FL-MMP-2, 1.8-fold; NTT-MMP-2, greater than 7-fold). Isoform-specific immunohistochemical staining revealed low, but detectable levels of the FL-MMP-2 isoform in controls, while NTT-MMP-2 was not detected. While there was a modest increase in tubular epithelial cell staining for FL-MMP-2 in STZ-treated mice, NTT-MMP-2 was intensely expressed in a basolateral pattern. FL-MMP-2 and NTT-MMP-2 isoform expression as quantified by qPCR were both significantly elevated in renal biopsies of human diabetic nephropathy (12-fold and 3-fold, respectively).


CONCLUSIONS
The expression of both isoforms of MMP-2 was enhanced in an experimental model of diabetic nephropathy and in human diabetic nephropathy. Selective MMP-2 isoform inhibition could offer a novel approach for the treatment of diabetic renal disease.
Biomedical Research Institute and Department of Internal Medicine, Pusan National University Hospital, Busan, Republic of Korea.
Sang Soo
SS
Kim
Department of Pathology, Pusan National University Yangsan Hospital, Yangsan, Gyeongnam, Republic of Korea.
Nari
N
Shin
MRC for Ischemic Tissue Regeneration, Medical Research Institute, and Department of Phamacology, Pusan National University School of Medicine, Yangsan, Republic of Korea.
Sun Sik
SS
Bae
Biomedical Research Institute and Department of Internal Medicine, Pusan National University Hospital, Busan, Republic of Korea.
Min Young
MY
Lee
Biomedical Research Institute and Department of Internal Medicine, Pusan National University Hospital, Busan, Republic of Korea.
Harin
H
Rhee
Research Institute for Convergence of Biomedical Science and Technology and Department of Internal Medicine, Pusan National University Yangsan Hospital, Yangsan, Gyeongnam, Republic of Korea.
Il Young
IY
Kim
Biomedical Research Institute and Department of Internal Medicine, Pusan National University Hospital, Busan, Republic of Korea.
Eun Young
EY
Seong
Research Institute for Convergence of Biomedical Science and Technology and Department of Internal Medicine, Pusan National University Yangsan Hospital, Yangsan, Gyeongnam, Republic of Korea.
Dong Won
DW
Lee
Research Institute for Convergence of Biomedical Science and Technology and Department of Internal Medicine, Pusan National University Yangsan Hospital, Yangsan, Gyeongnam, Republic of Korea.
Soo Bong
SB
Lee
Biomedical Research Institute and Department of Internal Medicine, Pusan National University Hospital, Busan, Republic of Korea.
Ihm Soo
IS
Kwak
The Department of Medicine, San Francisco Department of Veterans Affairs Medical Center/University of California San Francisco, San Francisco, California, United States of America.
David H
DH
Lovett
Biomedical Research Institute and Department of Internal Medicine, Pusan National University Hospital, Busan, Republic of Korea.
Sang Heon
http://orcid.org/0000-0002-8218-6974
SH
Song
D000818:Animals; D001786:Blood Glucose; D002461:Cell Line, Transformed; D003928:Diabetic Nephropathies / Q000235:genetics* / Q000378:metabolism; D004195:Disease Models, Animal; D004847:Epithelial Cells / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D018384:Oxidative Stress; D020033:Protein Isoforms
D001786:Blood Glucose; D020033:Protein Isoforms; D020778:Matrix Metalloproteinase 2