Canagliflozin inhibits hedgehog interacting protein (Hhip) induction of tubulopathy in diabetic Akita mice.

Renal hedgehog interacting protein (Hhip) activates sodium-glucose cotransporter 2 (Sglt2) expression and promotes tubular senescence in murine diabetic kidney disease (DKD), yet its underlying mechanism(s) are poorly understood. Here we study the effect of the SGLT2 inhibitor, canagliflozin on tubulopathy (fibrosis and apoptosis) in Akita/Hhip-transgenic (Tg) mice with overexpression of Hhip in their renal proximal tubular cells (RPTCs) and its relevant mechanisms. The DKD-tubulopathy with pronounced Sglt2 expression was aggravated in the kidney of Akita/Hhip-Tg cf.

Renal Tubule-Specific Angiotensinogen Deletion Attenuates SGLT2 Expression and Ameliorates Diabetic Kidney Disease in Murine Models of Type 1 Diabetes.

The role of the intrarenal renin-angiotensin system (iRAS) in diabetic kidney disease (DKD) progression remains unclear. In this study, we generated mice with renal tubule-specific deletion of angiotensinogen (Agt; RT-Agt-/-) in both Akita and streptozotocin (STZ)-induced mouse model of diabetes. Both Akita RT-Agt-/- and STZ-RT-Agt-/- mice exhibited significant attenuation of glomerular hyperfiltration, urinary albumin/creatinine ratio, glomerulomegaly and tubular injury.

Heterogeneous nuclear ribonucleoprotein F deficiency in mouse podocyte promotes podocytopathy mediated by methyltransferase-like 14 nuclear translocation resulting in Sirtuin 1 gene inhibition.

Heterogeneous nuclear ribonucleoprotein F (HnRNP F) is a key regulator for nucleic acid metabolism; however, whether HnRNP F expression is important in maintaining podocyte integrity is unclear. Nephroseq analysis from a registry of human kidney biopsies was performed. Age- and sex-matched podocyte-specific HnRNP F knockout (HnRNP F KO) mice and control (HnRNP F) were studied.

NRF2 Deficiency Attenuates Diabetic Kidney Disease in Db/Db Mice via Down-Regulation of Angiotensinogen, SGLT2, CD36, and FABP4 Expression and Lipid Accumulation in Renal Proximal Tubular Cells.

The role(s) of nuclear factor erythroid 2-related factor 2 (NRF2) in diabetic kidney disease (DKD) is/are controversial. We hypothesized that Nrf2 deficiency in type 2 diabetes (T2D) db/db mice (db/db knockout (KO)) attenuates DKD progression through the down-regulation of angiotensinogen (AGT), sodium-glucose cotransporter-2 (SGLT2), scavenger receptor CD36, and fatty -acid-binding protein 4 (FABP4), and lipid accumulation in renal proximal tubular cells (RPTCs). Db/db KO mice were studied at 16 weeks of age.

Advancing Discovery Research in Nephrology in Canada: A Conference Report From the 2021 Molecules and Mechanisms Mediating Kidney Health and Disease (M3K) Scientific Meeting and Investigator Summit.

Purpose Of Conference: New discoveries arising from investigations into fundamental aspects of kidney development and function in health and disease are critical to advancing kidney care. Scientific meetings focused specifically on fundamental biology of the kidney can facilitate interactions, support the development of collaborative groups, and accelerate translation of key findings. The Canadian fundamental kidney researcher community has lacked such a forum.

Hedgehog interacting protein activates sodium-glucose cotransporter 2 expression and promotes renal tubular epithelial cell senescence in a mouse model of type 1 diabetes.

Aims/hypothesis: Senescent renal tubular cells may be linked to diabetic kidney disease (DKD)-related tubulopathy. We studied mice with or without diabetes in which hedgehog interacting protein (HHIP) was present or specifically knocked out in renal tubules (Hhip-KO), hypothesising that local deficiency of HHIP in the renal tubules would attenuate tubular cell senescence, thereby preventing DKD tubulopathy.

Methods: Low-dose streptozotocin was employed to induce diabetes in both Hhip-KO and control (Hhip) mice.

Angiotensin II type-2-receptor stimulation ameliorates focal and segmental glomerulosclerosis in mice.

Podocyte damage and loss are the early event in the development of focal segmental glomerulosclerosis (FSGS). Podocytes express angiotensin II type-2-receptor (AT2R), which may play a key role in maintaining kidney integrity and function. Here, we examined the effects of AT2R deletion and AT2R agonist compound 21 (C21) on the evolution of FSGS.

Deletion of heterogeneous nuclear ribonucleoprotein F in renal tubules downregulates SGLT2 expression and attenuates hyperfiltration and kidney injury in a mouse model of diabetes.

Aims/hypothesis: We previously reported that renal tubule-specific deletion of heterogeneous nuclear ribonucleoprotein F (Hnrnpf) results in upregulation of renal angiotensinogen (Agt) and downregulation of sodium-glucose co-transporter 2 (Sglt2) in Hnrnpf knockout (KO) mice. Non-diabetic Hnrnpf KO mice develop hypertension, renal interstitial fibrosis and glycosuria with no renoprotective effect from downregulated Sglt2 expression. Here, we investigated the effect of renal tubular Hnrnpf deletion on hyperfiltration and kidney injury in Akita mice, a model of type 1 diabetes.

ATR deficiency in mice accelerates podocyte dysfunction in diabetic progeny in a sex-dependent manner.

Aims/hypothesis: The angiotensin II receptor type 2 (ATR) may be a potential therapeutic target for the treatment of hypertension and chronic kidney disease (CKD). The expression and function of ATR in the vasculature and kidney appear sexually dimorphic. We hypothesised that Agtr2 knockout dams (ATRKO) with gestational diabetes would program their offspring for subsequent hypertension and CKD in a sex-dependent manner.

Angiotensin II up-regulates sodium-glucose co-transporter 2 expression and SGLT2 inhibitor attenuates Ang II-induced hypertensive renal injury in mice.

Clinical trials indicate that sodium/glucose co-transporter 2 (SGLT2) inhibitors (SGLT2i) improve kidney function, yet, the molecular regulation of SGLT2 expression is incompletely understood. Here, we investigated the role of the intrarenal renin-angiotensin system (RAS) on SGLT2 expression. In adult non-diabetic participants in the Nephrotic Syndrome Study Network (NEPTUNE, n=163), multivariable linear regression analysis showed SGLT2 mRNA was significantly associated with angiotensinogen (AGT), renin, and angiotensin-converting enzyme (ACE) mRNA levels (P<0.

Overexpression of Nrf2 in Renal Proximal Tubular Cells Stimulates Sodium-Glucose Cotransporter 2 Expression and Exacerbates Dysglycemia and Kidney Injury in Diabetic Mice.

We investigated the impact of nuclear factor erythroid 2-related factor 2 (Nrf2) overexpression in renal proximal tubular cells (RPTCs) on blood glucose, kidney injury, and sodium-glucose cotransporter 2 (Sglt2) expression in diabetic Akita / transgenic (Tg) mice. Immortalized human RPTCs (HK2) stably transfected with plasmid containing the promoter and human kidneys from patients with diabetes were also studied. Nrf2 overexpression was associated with increased blood glucose, glomerular filtration rate, urinary albumin-to-creatinine ratio, tubulointerstitial fibrosis, and Sglt2 expression in Akita / Tg mice compared with their Akita littermates.

The Rationale and Evidence for SGLT2 Inhibitors as a Treatment for Nondiabetic Glomerular Disease.

Background: Recent studies show that sodium-glucose cotransporter 2 inhibitors (SGLT2i), originally approved for glycemic control in patients with type 2 diabetes, also exert renoprotective effects independently from effects on dysglycemia. Moreover, recent work indicates that SGLT2i treatment may be effective in patients with nondiabetic chronic kidney disease, including primary and secondary glomerular diseases.

Summary: SGLT2i lower blood glucose by blocking glucose resorption in the early renal proximal tubule through the glucose transporter, SGLT2, leading to enhanced urinary glucose excretion.

Comparison of the effects of insulin and SGLT2 inhibitor on the Renal Renin-Angiotensin system in type 1 diabetes mice.

Aims: SGLT2 inhibitors have been proposed as an adjunct to insulin therapy for glycemic control in type 1 diabetes (T1D) patients. However, concern has been raised due to an increase in renin-angiotensin-system (RAS) activity reported in a clinical trial in which an SGLT2 inhibitor was added while insulin dose was reduced in T1D patients. We previously reported that insulin inhibits intrarenal angiotensinogen (Agt) gene transcription and RAS activation.

Increased urinary excretion of hedgehog interacting protein (uHhip) in early diabetic kidney disease.

Glomerular endothelial cell (GEC) dysfunction occurs in diabetic kidney disease (DKD) and generally precedes albuminuria. We recently reported that hedgehog interacting protein (Hhip), highly expressed in GECs, contributes to DKD development in diabetic mice. Here, we hypothesized that urinary Hhip (uHhip) could identify early DKD; we tested uHhip in mice and humans with diabetes (DM).

Tubular Deficiency of Heterogeneous Nuclear Ribonucleoprotein F Elevates Systolic Blood Pressure and Induces Glycosuria in Mice.

We reported previously that overexpression of heterogeneous nuclear ribonucleoprotein F (Hnrnpf) in renal proximal tubular cells (RPTCs) suppresses angiotensinogen (Agt) expression, and attenuates systemic hypertension and renal injury in diabetic Hnrnpf-transgenic (Tg) mice. We thus hypothesized that deletion of Hnrnpf in the renal proximal tubules (RPT) of mice would worsen systemic hypertension and kidney injury, perhaps revealing novel mechanism(s). Tubule-specific Hnrnpf knockout (KO) mice were generated by crossbreeding Pax8-Cre mice with floxed Hnrnpf mice on a C57BL/6 background.

Hedgehog Interacting Protein (Hhip) Regulates Insulin Secretion in Mice Fed High Fat Diets.

Hedgehog interacting protein (Hhip) is essential for islet formation and beta-cell proliferation during pancreatic development; abnormally elevated Hhip expression has been linked to human pancreatitis. Here, we investigate the role of Hhip in modulating insulin secretion in adult Hhip mice (Hhip +/- vs. Hhip+/+) fed high fat diets (HFD).

Heterogeneous Nuclear Ribonucleoprotein F Mediates Insulin Inhibition of Bcl2-Modifying Factor Expression and Tubulopathy in Diabetic Kidney.

We investigated the molecular mechanism(s) by which insulin prevents Bcl2-modifying factor (Bmf)-induced renal proximal tubular cell (RPTC) apoptosis and loss in diabetic mice. Transgenic mice (Tg) mice specifically overexpressing human BMF in RPTCs and non-Tg littermates were studied at 10 to 20 weeks of age. Non-diabetic littermates, diabetic Akita mice +/- insulin implant, Akita Tg mice specifically overexpressing heterogeneous nuclear ribonucleoprotein F (hnRNP F) in their RPTCs and immortalized rat renal proximal tubular cells (IRPTCs) were also studied.

Hedgehog Interacting Protein Promotes Fibrosis and Apoptosis in Glomerular Endothelial Cells in Murine Diabetes.

We investigated whether renal hedgehog interacting protein (Hhip) expression contributes to the progression of diabetic nephropathy (DN) and studied its related mechanism(s) in vivo and in vitro. Here, we show that Hhip expression is highly elevated in glomerular endothelial cells of adult type 1 diabetic (T1D) Akita and T2D db/db mouse kidneys as compared to non-diabetic control littermates. Hyperglycemia enhances reactive oxygen species (ROS) generation via NADPH oxidase 4 (Nox4) activation and stimulates renal Hhip gene expression, and that elevated renal Hhip gene expression subsequently activates the TGFβ1- Smad2/3 cascade and promotes endothelial to mesenchymal transition associated with endothelial cell fibrosis/apoptosis in vivo and in vitro.

Nrf2 Deficiency Upregulates Intrarenal Angiotensin-Converting Enzyme-2 and Angiotensin 1-7 Receptor Expression and Attenuates Hypertension and Nephropathy in Diabetic Mice.

We investigated the role of nuclear factor erythroid 2-related factor 2 (Nrf2) in renin-angiotensin system (RAS) gene expression in renal proximal tubule cells (RPTCs) and in the development of systemic hypertension and kidney injury in diabetic Akita mice. We used adult male Akita Nrf2 knockout mice and Akita mice treated with trigonelline (an Nrf2 inhibitor) or oltipraz (an Nrf2 activator). We also examined rat immortalized RPTCs (IRPTCs) stably transfected with control plasmids or plasmids containing rat angiotensinogen (Agt), angiotensin-converting enzyme (ACE), angiotensin-converting enzyme-2 (Ace2), or angiotensin 1-7 (Ang 1-7) receptor (MasR) gene promoters.

Heterogeneous Nuclear Ribonucleoprotein F Stimulates Sirtuin-1 Gene Expression and Attenuates Nephropathy Progression in Diabetic Mice.

We investigated the mechanism of heterogeneous nuclear ribonucleoprotein F (hnRNP F) renoprotective action in a type 2 diabetes (T2D) mouse model (/). Immortalized rat renal proximal tubular cells (IRPTCs) and kidneys from humans with T2D were also studied. The / mice developed hyperglycemia, oxidative stress, and nephropathy at age 20 weeks compared with their / littermates.

Insulin Inhibits Nrf2 Gene Expression via Heterogeneous Nuclear Ribonucleoprotein F/K in Diabetic Mice.

Oxidative stress induces endogenous antioxidants via nuclear factor erythroid 2-related factor 2 (Nrf2), potentially preventing tissue injury. We investigated whether insulin affects renal Nrf2 expression in type 1 diabetes (T1D) and studied its underlying mechanism. Insulin normalized hyperglycemia, hypertension, oxidative stress, and renal injury; inhibited renal Nrf2 and angiotensinogen (Agt) gene expression; and upregulated heterogeneous nuclear ribonucleoprotein F and K (hnRNP F and hnRNP K) expression in Akita mice with T1D.

Angiotensin-(1-7): A Novel Peptide to Treat Hypertension and Nephropathy in Diabetes?

The renin-angiotensin system (RAS) plays a pivotal role in mammalian homeostasis physiology. The RAS can be delineated into a classical RAS (the pressor arm) including angiotensinogen (Agt), renin, angiotensin-converting enzyme (ACE), angiotensin II (Ang II) and angiotensin type 1 receptor (AT1R), and a counterbalancing novel RAS (the depressor arm) including Agt, renin, angiotensin-converting enzyme-2 (ACE-2), angiotensin-(1-7) (Ang 1-7) and Ang 1-7 receptor (or Mas receptor (MasR)). Hyperglycemia (diabetes) induces severe tissue oxidative stress, which stimulates the pressor arm of the renal RAS axis and leads to an increase in ACE/ACE-2 ratio, with excessive formation of Ang II.

Overexpression of heterogeneous nuclear ribonucleoprotein F stimulates renal Ace-2 gene expression and prevents TGF-β1-induced kidney injury in a mouse model of diabetes.

Aims/hypothesis: We investigated whether heterogeneous nuclear ribonucleoprotein F (hnRNP F) stimulates renal ACE-2 expression and prevents TGF-β1 signalling, TGF-β1 inhibition of Ace-2 gene expression and induction of tubulo-fibrosis in an Akita mouse model of type 1 diabetes.

Methods: Adult male Akita transgenic (Tg) mice overexpressing specifically hnRNP F in their renal proximal tubular cells (RPTCs) were studied. Non-Akita littermates and Akita mice served as controls.

Reactive Oxygen Species and Nuclear Factor Erythroid 2-Related Factor 2 Activation in Diabetic Nephropathy: A Hidden Target.

Hyperglycemia, oxidative stress and renin-angiotensin system (RAS) dysfunction have been implicated in diabetic nephropathy (DN) progression, but the underlying molecular mechanisms are far from being fully understood. In addition to the systemic RAS, the existence of a local intrarenal RAS in renal proximal tubular cells has been recognized. Angiotensinogen is the sole precursor of all angiotensins (Ang).

High Glucose Up-regulates ADAM17 through HIF-1α in Mesangial Cells.

We previously showed that ADAM17 mediates high glucose-induced matrix production by kidney mesangial cells. ADAM17 expression is increased in diabetic kidneys, suggesting that its up-regulation may augment high glucose profibrotic responses. We thus studied the effects of high glucose on ADAM17 gene regulation.