The phosphatase Shp1 interacts with and dephosphorylates cortactin to inhibit invadopodia function.

BACKGROUND: Invadopodia are actin-based cell-membrane protrusions associated with the extracellular matrix degradation accompanying cancer invasion. The elucidation of the molecular mechanisms leading to invadopodia formation and activity is central for the prevention of tumor spreading and growth. Protein tyrosine kinases such as Src are known to regulate invadopodia assembly, little is however known on the role of protein tyrosine phosphatases in this process. Among these enzymes, we have selected the tyrosine phosphatase Shp1 to investigate its potential role in invadopodia assembly, due to its involvement in cancer development. METHODS: Co-immunoprecipitation and immunofluorescence studies were employed to identify novel substrate/s of Shp1AQ controlling invadopodia activity. The phosphorylation level of cortactin, the Shp1 substrate identified in this study, was assessed by immunoprecipitation, in vitro phosphatase and western blot assays. Short interference RNA and a catalytically-dead mutant of Shp1 expressed in A375MM melanoma cells were used to evaluate the role of the specific Shp1-mediated dephosphorylation of cortactin. The anti-invasive proprieties of glycerophosphoinositol, that directly binds and regulates Shp1, were investigated by extracellular matrix degradation assays and in vivo mouse model of metastasis. RESULTS: The data show that Shp1 was recruited to invadopodia and promoted the dephosphorylation of cortactin at tyrosine 421, leading to an attenuated capacity of melanoma cancer cells to degrade the extracellular matrix. Controls included the use of short interference RNA and catalytically-dead mutant that prevented the dephosphorylation of cortactin and hence the decrease the extracellular matrix degradation by melanoma cells. In addition, the phosphoinositide metabolite glycerophosphoinositol facilitated the localization of Shp1 at invadopodia hence promoting cortactin dephosphorylation. This impaired invadopodia function and tumor dissemination both in vitro and in an in vivo model of melanomas. CONCLUSION: The main finding here reported is that cortactin is a specific substrate of the tyrosine phosphatase Shp1 and that its phosphorylation/dephosphorylation affects invadopodia formation and, as a consequence, the ability of melanoma cells to invade the extracellular matrix. Shp1 can thus be considered as a regulator of melanoma cell invasiveness and a potential target for antimetastatic drugs. Video abstract.

Case Report: Early Treatment With Chenodeoxycholic Acid in Cerebrotendinous Xanthomatosis Presenting as Neonatal Cholestasis.

Background: Cerebrotendinous xanthomatosis (CTX) is an inborn disorder of bile acid synthesis which causes progressive accumulation of toxic metabolites in various organs, particularly in brain and tendons. Most cases are diagnosed and treated in the second or third decade of life, when neurological involvement appears. We describe a case of CTX presenting as neonatal cholestasis. Results: The child presented cholestasis at 2 months of life. In the following months jaundice slowly disappeared, with a normalization of bilirubin and aminotransferases, respectively, at 6 and 8 months. A LC-Mass Spectrometry of the urines showed the presence of cholestanepentols glucuronide, which led to the suspicion of cerebrotendinous xanthomatosis. The diagnosis was confirmed by the dosage of cholestanol in serum and the molecular genetic analysis of the CYP27A1 gene. Therapy with chenodeoxycholic acid (CDCA) was started at 8 months and is still ongoing. The child was monitored for 13 years by dosage of serum cholestanol and urinary cholestanepentols. A strictly biochemical and neurological follow up was performed and no sign of neurological impairment was observed. Conclusions: Prompt diagnosis and treatment of CTX presenting as neonatal cholestasis may prevent further neurological impairment.

Pediatric autoimmune liver disease and extra-hepatic immune-mediated comorbidities.

BACKGROUND: Autoimmune liver disease (AILD) includes autoimmune hepatitis (AIH) and autoimmune sclerosing cholangitis (ASC). AILD is often associated with other extra-hepatic immune-mediated disorders (EDs), but there are few pediatric studies available to date. In this study we evaluated the association between AILD and EDs in our pediatric series. METHODS: In this single centre retrospective study 48 patients (39 AIH and 9 ASC children) were evaluated. Thirty-six children were primarily referred to our Centre for liver disease suspicion, while the remaining twelve had a previous diagnosis of EDs. All the patients were screened for various EDs at AILD diagnosis and yearly during the follow-up. RESULTS: Mean duration of follow-up was 9 years and 1 month. Twenty-two (46%) patients had a diagnosis of EDs. Ulcerative colitis (UC) was the most frequent EDs (9 patients), followed by autoimmune thyroid disease (5 patients) and celiac disease (5 patients). In 7 out of 9 UC patients, ASC was present. CONCLUSIONS: Our study showed a high association (46%) between AILD and EDs. In particular, in 8 out of 9 ASC patients UC was diagnosed (p-value 0.007). It is important to look for EDs in AILD children and, conversely, AILD in EDs children with abnormal liver function tests.

Renal phosphate handling in Gitelman syndrome--the results of a case-control study.

BACKGROUND: Patients with Gitelman syndrome, a hereditary salt-wasting tubulopathy, have loss-of-function mutations in the SLC12A3 gene coding for the thiazide-sensitive sodium chloride co-transporter in the distal convoluted tubule. Since the bulk of filtered phosphate is reabsorbed in the proximal tubule, renal phosphate wasting is considered exceptional in Gitelman syndrome. METHODS: We investigated the renal handling of inorganic phosphate in 12 unselected Italian patients affected with Gitelman syndrome (5 females and 7 males, aged 6.0-18 years, median age 12 years) and in 12 healthy subjects matched for gender and age (controls). The diagnosis of Gitelman syndrome among the patients had been made clinically and confirmed by molecular biology studies. RESULTS: The biochemical hallmarks of Gitelman syndrome, namely hypochloremia, hypokalemia, hypomagnesemia, increased urinary excretion of sodium, chloride, potassium and magnesium and reduced urinary excretion of calcium, were present in the 12 patients. In addition, both the plasma inorganic phosphate concentration (median and interquartile range: 1.28 [1.12-1.36] vs. 1.61 [1.51-1.66)] mmol/L) and the maximal tubular reabsorption of inorganic phosphate (1.08 [0.99-1.22] vs. 1.41 [1.38-1.47] mmol/L) were significantly lower (P < 0.001) in Gitelman patients than in control subjects. Circulating levels of 25-hydroxyvitamin D, intact parathyroid hormone and osteocalcin were similar in patients and controls. CONCLUSIONS: The results of our case-control study disclose a hitherto unrecognized tendency towards renal phosphate wasting with mild to moderate hypophosphatemia in Gitelman syndrome.

[Acute hepatitis as a side effect of albendazole: a pediatric case]. / Epatite acuta itterica da Albendazolo: un caso pediatrico.

We describe a case of acute hepatitis with jaundice in a patient of seven years of age in oral treatment with albendazole; a mild increase of liver function tests is a well-known side effect after prolonged administration but acute hepatitis has never been described in childhood.

[Acute hepatitis as a side effect of albendazole: a pediatric case]. / Epatite acuta itterica da albendazolo: un caso pediatrico.

We describe a case of acute hepatitis with jaundice in a patient of seven years of age in oral treatment with albendazole; a mild increase of liver function tests is a well-known side effect after prolonged administration but acute hepatitis has never been described in childhood.