Deletion of Nedd4-2 results in progressive kidney disease in mice

NEDD4-2 (NEDD4L), a ubiquitin protein ligase of the Nedd4 family, is a key regulator of cell surface expression and activity of the amiloride-sensitive epithelial Na⁺ channel (ENaC). While hypomorphic alleles of Nedd4-2 in mice show salt-sensitive hypertension, complete knockout results in pulmonary distress and perinatal lethality due to increased cell surface levels of ENaC. We now show that Nedd4-2 deficiency in mice also results in an unexpected progressive kidney injury phenotype associated with elevated ENaC and Na⁺Cl⁻ cotransporter expression, increased Na⁺ reabsorption, hypertension and markedly reduced levels of aldosterone. The observed nephropathy is characterized by fibrosis, tubule epithelial cell apoptosis, dilated/cystic tubules, elevated expression of kidney injury markers and immune cell infiltration, characteristics reminiscent of human chronic kidney disease. Importantly, we demonstrate that the extent of kidney injury can be partially therapeutically ameliorated in mice with nephron-specific deletions of Nedd4-2 by blocking ENaC with amiloride. These results suggest that increased Na⁺ reabsorption via ENaC causes kidney injury and establish a novel role of NEDD4-2 in preventing Na⁺-induced nephropathy. Contrary to some recent reports, our data also indicate that ENaC is the primary in vivo target of NEDD4-2 and that Nedd4-2 deletion is associated with hypertension on a normal Na⁺ diet. These findings provide further insight into the critical function of NEDD4-2 in renal pathophysiology.Tanya L Henshall, Jantina A Manning, Omri S Alfassy, Pranay Goel, Natasha A Boase, Hiroshi Kawabe and Sharad Kuma

Huntingtin function during zebrafish (Danio rerio) development.

Huntington’s disease shares a common molecular basis with eight other neurodegenerative diseases: expansion of an existing polyglutamine tract. In each case, this repeat tract occurs within otherwise unrelated proteins. These proteins show widespread and overlapping patterns of expression in the brain and yet the diseases are distinguished by neurodegeneration in a specific subset of neurons that are most sensitive to the mutation. It has therefore been proposed that expansion of the polyglutamine region in these genes may result in perturbation of the normal function of the respective proteins, and that this perturbation in some way contributes to the neuronal specificity of these diseases. The normal functions of these proteins have therefore become a focus of investigation as potential pathogenic pathways. Here, synthetic antisense morpholinos have been used to inhibit the translation of huntingtin protein during early zebrafish development. The results obtained show the effects of huntingtin loss-of-function on the developing nervous system, including distinct defects in morphology of the lateral line neuromasts, olfactory placode and branchial arches. The potential common origins of these defects were explored, revealing impaired formation of the anterior-most region of the neural plate as indicated by reduced pre-placodal and telencephalic gene expression with no effect on mid- or hindbrain formation. These investigations demonstrate a specific ‘rate-limiting’ role for huntingtin in formation of the telencephalon and the pre-placodal region, and differing levels of requirement for huntingtin function in specific nerve cell types.Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 201

Global levels of specific histone modifications and an epigenetic gene signature predict prostate cancer progression and development

BackgroundEpigenetic alterations are common in prostate cancer, yet how these modifications contribute to carcinogenesis is poorly understood. We investigated whether specific histone modifications are prognostic for prostate cancer relapse, and whether the expression of epigenetic genes is altered in prostate tumorigenesis.MethodsGlobal levels of histone H3 lysine-18 acetylation (H3K18Ac) and histone H3 lysine-4 dimethylation (H3K4diMe) were assessed immunohistochemically in a prostate cancer cohort of 279 cases. Epigenetic gene expression was investigated in silico by analysis of microarray data from 23 primary prostate cancers (8 with biochemical recurrence and 15 without) and 7 metastatic lesions.ResultsH3K18Ac and H3K4diMe are independent predictors of relapse-free survival, with high global levels associated with a 1.71-fold (P ConclusionsThis study has established the importance of histone modifications in predicting prostate cancer relapse and has identified an epigenetic gene signature associated with prostate tumorigenesis.ImpactOur findings suggest that targeting the epigenetic enzymes specifically involved in a particular solid tumor may be a more effective approach. Moreover, testing for aberrant expression of epigenetic genes such as those identified in this study may be beneficial in predicting individual patient response to epigenetic therapies.Tina Bianco-Miotto... Grant Buchanan... Melissa A. O'Loughlin... et al