Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a common genetic disorder characterized by bilateral renal cyst formation1. Recent identification of signaling cascades de-regulated in ADPKD has led to the initiation of several clinical trials, but an approved therapy is still lacking2,3. Using a metabolomic approach here we identify a pathogenic pathway in ADPKD which can be safely targeted for therapy. We show that mutation in PKD1 results in enhanced glycolysis in cells, in a murine model of PKD, and in human-derived ADPKD kidneys. Glucose deprivation reduced proliferation and sensitized PKD1 mutant cells to apoptosis. Notably, treatment of two distinct PKD mouse models with 2-deoxyglucose (2DG) ameliorates kidney volume, cystic index and reduced proliferation rates. These metabolic alterations depend on the ERK pathway acting in a dual manner by inhibiting the LKB1-AMPK axis on the one hand while activating the mTORC1-glycolytic cascade on the other. Enhanced metabolic rates further inhibit AMPK. Forced activation of AMPK acts in a negative feedback loop restoring normal ERK activity. Taken together, these data indicate that defective glucose metabolism is intimately involved in the pathobiology of ADPKD. Our findings provide a strong rationale for a novel therapeutic paradigm using existing drugs, either individually or in combination.

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disease characterized by bilateral renal cyst formation. Both hyperproliferation and hypertrophy have been previously observed in ADPKD kidneys. Polycystin-1 (PC-1), a large orphan receptor encoded by the PKD1 gene and mutated in 85% of all cases, is able to inhibit proliferation and apoptosis. Here we show that overexpression of PC-1 in renal epithelial cells inhibits cell growth (size) in a cell cycle-independent manner due to the downregulation of mTOR, S6K1, and 4EBP1. Upregulation of the same pathway leads to increased cell size, as found in mouse embryonic fibroblasts derived from Pkd1 ؊/؊ mice. We show that PC-1 controls the mTOR pathway in a Tsc2-dependent manner, by inhibiting the extracellular signal-regulated kinase (ERK)-mediated phosphorylation of tuberin in Ser664. We provide a detailed molecular mechanism by which PC-1 can inhibit the mTOR pathway and regulate cell size.

Background Circulating androgens could have a relevant pathobiological role in clinical outcomes in men with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection (COVID‐19). Objectives We aimed to assess: (a) circulating sex steroids levels in a cohort of 286 symptomatic men with laboratory‐confirmed COVID‐19 at hospital admission compared to a cohort of 281 healthy men; and (b) the association between serum testosterone levels (tT), COVID‐19, and clinical outcomes. Materials and Methods Demographic, clinical, and hormonal values were collected for all patients. Hypogonadism was defined as tT ≤9.2 nmol/l. The Charlson Comorbidity Index (CCI) was used to score health‐significant comorbidities. Severe clinical outcomes were defined as patients either transferred to intensive care unit (ICU) or death. Descriptive statistics and multivariable linear and logistic regression models tested the association between clinical and laboratory variables and tT levels. Univariable and multivariable logistic regression models tested the association between tT and severe clinical outcomes. Results Overall, a significantly lower levels of LH and tT were found in patients with COVID‐19 compared to healthy controls (all p < 0.0001); conversely, healthy controls depicted lower values of circulating E 2 ( p < 0.001). Testosterone levels suggestive for hypogonadism were observed in 257 (89.8%) patients at hospital admission. In as many as 243 (85%) cases, hypogonadism was secondary. SARS‐CoV‐2 infection status was independently associated with lower tT levels ( p < 0.0001) and greater risk of hypogonadism ( p < 0.0001), after accounting for age, BMI, CCI, and IL‐6 values. Lower tT levels were associated with higher risk of ICU admission and death outcomes (all p ≤ 0.05), after accounting for clinical and laboratory parameters. Conclusions We unveil an independent association between SARS‐CoV‐2 infection status and secondary hypogonadism already at hospital admission, with lower testosterone levels predicting the most severe clinical outcomes.

Autosomal dominant polycystic kidney disease (ADPKD) is an important cause of ESRD for which there exists no approved therapy in the United States. Defective glucose metabolism has been identified as a feature of ADPKD, and inhibition of glycolysis using glucose analogs ameliorates aggressive PKD in preclinical models. Here, we investigated the effects of chronic treatment with low doses of the glucose analog 2-deoxy-D-glucose (2DG) on ADPKD progression in orthologous and slowly progressive murine models created by inducible inactivation of the Pkd1 gene postnatally. As previously reported, early inactivation (postnatal days 11 and 12) of Pkd1 resulted in PKD developing within weeks, whereas late inactivation (postnatal days 25-28) resulted in PKD developing in months. Irrespective of the timing of Pkd1 gene inactivation, cystic kidneys showed enhanced uptake of 13 C-glucose and conversion to 13 C-lactate. Administration of 2DG restored normal renal levels of the phosphorylated forms of AMPactivated protein kinase and its target acetyl-CoA carboxylase. Furthermore, 2DG greatly retarded disease progression in both model systems, reducing the increase in total kidney volume and cystic index and markedly reducing CD45-positive cell infiltration. Notably, chronic administration of low doses (100 mg/kg 5 days per week) of 2DG did not result in any obvious sign of toxicity as assessed by analysis of brain and heart histology as well as behavioral tests. Our data provide proof of principle support for the use of 2DG as a therapeutic strategy in ADPKD.

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a genetic disorder caused by loss-of-function mutations in PKD1 or PKD2. Increased glycolysis is a prominent feature of the disease, but how it impacts on other metabolic pathways is unknown. Here, we present an analysis of mouse Pkd1 mutant cells and kidneys to investigate the metabolic reprogramming of this pathology. We show that loss of Pkd1 leads to profound metabolic changes that affect glycolysis, mitochondrial metabolism, and fatty acid synthesis (FAS). We find that Pkd1-mutant cells preferentially use glutamine to fuel the TCA cycle and to sustain FAS. Interfering with either glutamine uptake or FAS retards cell growth and survival. We also find that glutamine is diverted to asparagine via asparagine synthetase (ASNS). Transcriptional profiling of PKD1-mutant human kidneys confirmed these alterations. We find that silencing of Asns is lethal in Pkd1-mutant cells when combined with glucose deprivation, suggesting therapeutic approaches for ADPKD.

Polycystin-1 (PC-1), the product of the PKD1 gene, mutated in the majority of cases of Autosomal Dominant Polycystic Kidney Disease (ADPKD), is a very large (∼520 kDa) plasma membrane receptor localized in several subcellular compartments including cell-cell/matrix junctions as well as cilia. While heterologous over-expression systems have allowed identification of several of the potential biological roles of this receptor, its precise function remains largely elusive. Studying PC-1 in vivo has been a challenging task due to its complexity and low expression levels. To overcome these limitations and facilitate the study of endogenous PC-1, we have inserted HA- or Myc-tag sequences into the Pkd1 locus by homologous recombination. Here, we show that our approach was successful in generating a fully functional and easily detectable endogenous PC-1. Characterization of PC-1 distribution in vivo showed that it is expressed ubiquitously and is developmentally-regulated in most tissues. Furthermore, our novel tool allowed us to investigate the role of PC-1 in brain, where the protein is abundantly expressed. Subcellular localization of PC-1 revealed strong and specific staining in ciliated ependymal and choroid plexus cells. Consistent with this distribution, we observed hydrocephalus formation both in the ubiquitous knock-out embryos and in newborn mice with conditional inactivation of the Pkd1 gene in the brain. Both choroid plexus and ependymal cilia were morphologically normal in these mice, suggesting a role for PC-1 in ciliary function or signalling in this compartment, rather than in ciliogenesis. We propose that the role of PC-1 in the brain cilia might be to prevent hydrocephalus, a previously unrecognized role for this receptor and one that might have important implications for other genetic or sporadic diseases.

Several organs, including lungs and kidneys, are formed by epithelial tubes whose proper morphogenesis ensures correct function. This is best exemplified by the kidney, where defective establishment or maintanance of tubular diameter results in polycystic kidney disease, a common genetic disorder. Most polycystic kidney disease cases result from loss-of-function mutations in the PKD1 gene, encoding Polycystin-1 (PC-1), a large receptor of unknown function. Here we demonstrate that PC-1 plays an essential role in establishment of correct tubular diameter during nephron development. PC-1 associates with Par3 favoring the assembly of a pro-polarizing Par3/aPKC complex and it regulates a program of cell polarity important for oriented cell migration and for a convergent extension-like process during tubular morphogenesis. Par3 inactivation in the developing kidney results in defective convergent extension and tubular morphogenesis and in renal cyst formation. Our data define PC-1 as central to cell polarization and to epithelial tube morphogenesis and homeostasis.

Background: Circulating testosterone levels have been found to be reduced in men with severe acute respiratory syndrome coronavirus 2 infection, COVID-19, with lower levels being associated with more severe clinical outcomes. Objectives:We aimed to assess total testosterone levels and the prevalence of total testosterone still suggesting for hypogonadism at 7-month follow-up in a cohort of 121 men who recovered from laboratory-confirmed COVID-19.Materials and methods: Demographic, clinical, and hormonal values were collected for all patients. Hypogonadism was defined as total testosterone ≤9.2 nmol/L. The Charlson Comorbidity Index was used to score health-significant comorbidities. Descriptive statistics and multivariable linear and logistic regression models tested the association between clinical and laboratory variables and total testosterone levels at follow-up assessment.