Peroxisome proliferator-activated receptor ɣ agonist mediated inhibition of heparanase expression reduces proteinuria.

Background: Proteinuria is associated with many glomerular diseases and a risk factor for the progression to renal failure. We previously showed that heparanase (HPSE) is essential for the development of proteinuria, whereas peroxisome proliferator-activated receptor ɣ (PPARɣ) agonists can ameliorate proteinuria. Since a recent study showed that PPARɣ regulates HPSE expression in liver cancer cells, we hypothesized that PPARɣ agonists exert their reno-protective effect by inhibiting glomerular HPSE expression.

The Calcium-Dependent Protease Calpain-1 Links TRPC6 Activity to Podocyte Injury.

Background: The hallmark of podocytopathies, such as FSGS, is podocyte injury resulting in proteinuria. Transient receptor potential channel C6 (TRPC6) is a calcium-conducting ion channel expressed at the slit diaphragm. TRPC6 gain-of-function mutations and glomerular TRPC6 overexpression are associated with proteinuria.

IL-1β Promotes a New Function of DNase I as a Transcription Factor for the Fas Receptor Gene.

Recently we described that endonuclease inactive DNase I translocated into the nucleus in response to increased endogenous IL-1β expression. Here, we demonstrate impact and function of translocated DNase I in tubular cells. Effect of cytokines on expression level and nuclear localisation of DNase I and corresponding levels of Fas receptor (FasR) and IL-1β were determined by confocal microscopy, qPCR and western blot analyses, in presence or absence of siRNA against IL-1β and DNase I mRNA.

Sildenafil Prevents Podocyte Injury PPAR--Mediated TRPC6 Inhibition.

Transient receptor potential channel C6 (TRPC6) gain-of-function mutations and increased TRPC6 expression in podocytes induce glomerular injury and proteinuria. Sildenafil reduces TRPC6 expression and activity in nonrenal cell types, although the mechanism is unknown. Peroxisome proliferator-activated receptor (PPAR-) is a downstream target of sildenafil in the cyclic guanosine monophosphate (cGMP)-activated protein kinase G (PKG) axis.

1,25-Vitamin D3 Deficiency Induces Albuminuria.

Vitamin D plays an important role in renal (patho)physiology. Patients with glomerular diseases have an injured renal filtration barrier, leading to proteinuria and reduced renal function. An impaired renal function also leads to 1,25-vitamin D3 deficiency as a result of reduced renal 1α-hydroxylase activity.

Vitamin D attenuates proteinuria by inhibition of heparanase expression in the podocyte.

The glomerular filtration barrier consists of podocytes, the glomerular basement membrane, and endothelial cells covered with a glycocalyx. Heparan sulphate (HS) in the glomerular filtration barrier is reduced in patients with proteinuria, which is associated with increased expression of the HS-degrading enzyme heparanase. Previously, we showed that heparanase is essential for the development of proteinuria in experimental diabetic nephropathy.

Glucose specifically regulates TRPC6 expression in the podocyte in an AngII-dependent manner.

Slit diaphragm and podocyte damage is crucial in the pathogenesis of proteinuria in diabetic nephropathy (DNP). Gain-of-function mutations in TRPC6, a slit diaphragm-associated ion channel, cause glomerulosclerosis; TRPC6 expression is increased in acquired glomerular disease. Hyperglycemia and high intrarenal angiotensin II (AngII) levels could contribute to podocyte injury in DNP.

Early development of hyperparathyroidism due to loss of PTH transcriptional repression in patients with HNF1β mutations?

Context: Heterozygous mutations or deletions of the transcription factor hepatocyte nuclear factor 1β (HNF1β) result in a heterogeneous syndrome characterized by renal cysts and diabetes, together with a variety of other extrarenal and renal manifestations. Interestingly, in several patients with HNF1β abnormalities, we observed early hyperparathyroidism and PTH levels that we judged inappropriately high compared with the degree of renal function decline.

Objective: Based on the above clinical observations, we tested the hypothesis of a direct role of HNF1β in the transcriptional regulation of the human PTH gene in the parathyroid gland.

Vitamin D down-regulates TRPC6 expression in podocyte injury and proteinuric glomerular disease.

The transient receptor potential cation channel C6 (TRPC6) is a slit diaphragm protein expressed by podocytes. TRPC6 gain-of-function mutations cause autosomal dominant focal segmental glomerulosclerosis. In acquired proteinuric renal disease, glomerular TRPC6 expression is increased.