Journal Article

Role of MKK3-p38 MAPK signalling in the development of type 2 diabetes and renal injury in obese db/db mice

Ozols, E, Thomas, M. C, Ma, F. Y, Davis, R. J, Nikolic-Paterson, D. J, Lim, A. K. H, Tesch, G. H, Flavell, R. A

2009

Overview

Aims/hypothesis Obesity and diabetes are associated with increased intracellular p38 mitogen-activated protein kinase (MAPK) signalling, which may promote tissue inflammation and injury. Activation of p38 MAPK can be induced by either of the immediate upstream kinases, MAP kinase kinase (MKK)3 or MKK6, and recent evidence suggests that MKK3 has non-redundant roles in the pathology attributed to p38 MAPK activation. Therefore, this study examined whether MKK3 signalling influences the development of obesity, type 2 diabetes and diabetic nephropathy. Methods Wild-type and Mkk3 (also known as Map2k3) gene-deficient db/db mice were assessed for the development of obesity, type 2 diabetes and renal injury from 8 to 32 weeks of age. Results Mkk3 ⁺/⁺ db/db and Mkk3 ⁻/⁻ db/db mice developed comparable obesity and were similar in terms of incidence and severity of type 2 diabetes. At 32 weeks, diabetic Mkk3 ⁺/⁺ db/db mice had increased kidney levels of phospho-p38 and MKK3 protein. In comparison, kidney levels of phospho-p38 in diabetic Mkk3 ⁻/⁻ db/db mice remained normal, despite a fourfold compensatory increase in MKK6 protein levels. The reduced levels of p38 MAPK signalling in the diabetic kidneys of Mkk3 ⁻/⁻ db/db mice was associated with protection against the following: declining renal function, increasing albuminuria, renal hypertrophy, podocyte loss, mesangial cell activation and glomerular fibrosis. Diabetic Mkk3 ⁻/⁻ db/db mice were also significantly protected from tubular injury and interstitial fibrosis, which was associated with reduced Ccl2 mRNA expression and interstitial macrophage accumulation. Conclusions/interpretation MKK3-p38 MAPK signalling is not required for the development of obesity or type 2 diabetes, but plays a distinct pathogenic role in the progression of diabetic nephropathy in db/db mice.

• Publisher: Berlin/Heidelberg : Springer-Verlag,Springer-Verlag,Springer,Springer Nature B.V
• Subject: Aging / Aging - genetics / Aging - physiology / Animals / Apoptosis / Biological and medical sciences / db/db mice / deficiency / Diabetes / Diabetes Mellitus, Type 2 / Diabetes Mellitus, Type 2 - enzymology / Diabetes Mellitus, Type 2 - epidemiology / Diabetes Mellitus, Type 2 - physiopathology / Diabetes. Impaired glucose tolerance / Diabetic Nephropathies / Diabetic Nephropathies - enzymology / Diabetic Nephropathies - genetics / Diabetic Nephropathies - pathology / Diabetic nephropathy / DNA Probes / Endocrine pancreas. Apud cells (diseases) / Endocrinopathies / enzymology / epidemiology / Etiopathogenesis. Screening. Investigations. Target tissue resistance / Fibroblasts / genetics / Glucose / Growth factors / Human Physiology / Hyperglycemia / Hypertrophy / Inflammation / injuries / Injuries of the urinary system. Foreign bodies. Diseases due to physical agents / Internal Medicine / Kidney / Kidney - injuries / Kidney - pathology / Kidney - physiopathology / Kidneys / Kinases / Macrophage / MAP Kinase Kinase 3 / MAP Kinase Kinase 3 - deficiency / MAP Kinase Kinase 3 - genetics / MAP Kinase Kinase 3 - metabolism / MCP-1 / Medical sciences / Medicine / Medicine & Public Health / Metabolic Diseases / metabolism / Mice / Mice, Inbred Strains / Mice, Knockout / Mice, Obese / MKK3 / Nephrology. Urinary tract diseases / Obesity / p38 MAPK / p38 Mitogen-Activated Protein Kinases / p38 Mitogen-Activated Protein Kinases - metabolism / pathology / physiology / physiopathology / Podocyte / Proteins / Receptors, Leptin / Receptors, Leptin - genetics / Traumas. Diseases due to physical agents / Tumor Necrosis Factor-alpha / Tumor Necrosis Factor-alpha - genetics / Urinary system involvement in other diseases. Miscellaneous