Concurrent Moyamoya-like Intracranial Steno-Occlusive Disease and Dural Arteriovenous Fistulas.

The simultaneous presentation of intracranial steno-occlusive disease, Moyamoya disease, or Moyamoya-like vasculopathy and dural arteriovenous fistulas (DAVFs) has been documented in very few case reports worldwide. We aimed to better characterize this association by reviewing the clinical and radiologic findings of 4 patients with concurrent intracranial steno-occlusive disease or Moyamoya-like vasculopathy and DAVFs evaluated in our institution. All 4 patients were of Asian descent. One patient presented with ischemic stroke secondary to intracranial stenosis, 2 presented with symptoms related to the DAVF, and the diagnosis was incidental in the fourth patient. Three patients underwent embolization of the DAVF, which was followed by surgical ligation in 2. One patient underwent extracranial-intracranial bypass for Moyamoya-like intracranial steno-occlusive disease. One patient is being managed conservatively with close follow-up. Our case series details findings in 4 patients with associated intracranial steno-occlusive disease and DAVFs. Further studies and reporting of similar cases are necessary to establish whether this is pure coincidence or if there is indeed a relationship between these 2 conditions, especially in certain ethnic groups.

Murine Epsins Play an Integral Role in Podocyte Function.

BACKGROUND: Epsins, a family of evolutionarily conserved membrane proteins, play an essential role in endocytosis and signaling in podocytes. METHODS: Podocyte-specific Epn1, Epn2, Epn3 triple-knockout mice were generated to examine downstream regulation of serum response factor (SRF) by cell division control protein 42 homolog (Cdc42). RESULTS: Podocyte-specific loss of epsins resulted in increased albuminuria and foot process effacement. Primary podocytes isolated from these knockout mice exhibited abnormalities in cell adhesion and spreading, which may be attributed to reduced activation of cell division control protein Cdc42 and SRF, resulting in diminished ß1 integrin expression. In addition, podocyte-specific loss of Srf resulted in severe albuminuria and foot process effacement, and defects in cell adhesion and spreading, along with decreased ß1 integrin expression. CONCLUSIONS: Epsins play an indispensable role in maintaining properly functioning podocytes through the regulation of Cdc42 and SRF-dependent ß1 integrin expression.

Inhibition of Endocytosis of Clathrin-Mediated Angiotensin II Receptor Type 1 in Podocytes Augments Glomerular Injury.

BACKGROUND: Inhibition of the renin-angiotensin system remains a cornerstone in reducing proteinuria and progression of kidney failure, effects believed to be the result of reduction in BP and glomerular hyperfiltration. However, studies have yielded conflicting results on whether podocyte-specific angiotensin II (AngII) signaling directly induces podocyte injury. Previous research has found that after AngII stimulation, ß-arrestin-bound angiotensin II receptor type 1 (AT1R) is internalized in a clathrin- and dynamin-dependent manner, and that Dynamin1 and Dynamin2 double-knockout mice exhibit impaired clathrin-mediated endocytosis. METHODS: We used podocyte-specific Dyn double-knockout mice to examine AngII-stimulated AT1R internalization and signaling in primary podocytes and controls. We also examined the in vivo effect of AngII in these double-knockout mice through renin-angiotensin system blockers and through deletion of Agtr1a (which encodes the predominant AT1R isoform expressed in kidney, AT1aR). We tested calcium influx, Rac1 activation, and lamellipodial extension in control and primary podocytes of Dnm double-knockout mice treated with AngII. RESULTS: We confirmed augmented AngII-stimulated AT1R signaling in primary Dnm double-knockout podocytes resulting from arrest of clathrin-coated pit turnover. Genetic ablation of podocyte Agtr1a in Dnm double-knockout mice demonstrated improved albuminuria and kidney function compared with the double-knockout mice. Isolation of podocytes from Dnm double-knockout mice revealed abnormal membrane dynamics, with increased Rac1 activation and lamellipodial extension, which was attenuated in Dnm double-knockout podocytes lacking AT1aR. CONCLUSIONS: Our results indicate that inhibiting aberrant podocyte-associated AT1aR signaling pathways has a protective effect in maintaining the integrity of the glomerular filtration barrier.