Mutation analysis of three genes encoding novel LKB1-interacting proteins, BRG1, STRADα, and MO25α, in Peutz–Jeghers syndrome

Mutations in LKB1 lead to Peutz–Jeghers syndrome (PJS). However, only a subset of PJS patients harbours LKB1 mutations. We performed a mutation analysis of three genes encoding novel LKB1-interacting proteins, BRG1, STRADα, and MO25α, in 28 LKB1-negative PJS patients. No disease-causing mutations were detected in the studied genes in PJS patients from different European populations

Findings from the Peutz-Jeghers Syndrome Registry of Uruguay

Background: Peutz-Jeghers syndrome (PJS) is characterized by intestinal polyposis, mucocutaneous pigmentation and an increased cancer risk, usually caused by mutations of the STK11 gene. This study collected epidemiological, clinical and genetic data from all Uruguayan PJS patients. Methods: Clinical data were obtained from public and private medical centers and updated annually. Sequencing of the STK11 gene in one member of each family was performed. Results and discussion: 25 cases in 11 unrelated families were registered (15 males, 10 females). The average age of diagnosis and death was 18 and 41 years respectively. All patients had characteristic PJS pigmentation and gastrointestinal polyps. 72% required urgent surgery due to intestinal obstruction. 3 families had multiple cases of seizure disorder, representing 20% of cases. 28% developed cancer and two patients had more than one cancer. An STK11 mutation was found in 8 of the 9 families analyzed. A unique M136K missense mutation was noted in one family. Comparing annual live births and PJS birth records from 1970 to 2009 yielded an incidence of 1 in 155,000. Conclusion: The Uruguayan Registry for Peutz-Jeghers patients showed a high chance of emergent surgery, epilepsy, cancer and shortened life expectancy. The M136K missense mutation is a newly reported STK 11 mutation

Mutations in STK11 gene in Czech Peutz-Jeghers patients

<p>Abstract</p> <p>Background</p> <p>Peutz-Jeghers syndrome (PJS) is an autosomal dominant hereditary disease characterized by mucocutaneous pigmentation and gastrointestinal hamartomatous polyposis. The germline mutations in the serine/threonine kinase 11 (<it>STK11</it>) gene have been shown to be associated with the disease. Individuals with PJS are at increased risk for development of various neoplasms. The aim of the present study was to characterize the genotype and phenotype of Czech patients with PJS.</p> <p>Methods</p> <p>We examined genomic DNA of 8 individuals from five Czech families by sequencing analysis of <it>STK11 </it>gene, covering its promotor region, the entire coding region and the splice-site boundaries, and by multiplex ligation-dependent probe amplification (MLPA) assay designed for the identification of large exonic deletions or duplications of <it>STK11 </it>gene.</p> <p>Results</p> <p>We found pathogenic mutations in <it>STK11 </it>gene in two families fulfilling the diagnostic criteria of PJS and in one of three sporadic cases not complying with the criteria. The patient with the frameshift mutation in <it>STK11 </it>gene developed aggressive gastric cancer. No other studied proband has developed a carcinoma so far.</p> <p>Conclusion</p> <p>Our results showed that a germline mutation of <it>STK11 </it>gene can be found not only in probands fulfilling the PJS diagnostic criteria, but also in some sporadic cases not complying with the criteria. Moreover, we observed a new case of aggressive gastric cancer in a young patient with a frameshift mutation of <it>STK11 </it>gene.</p

LKB1 Destabilizes Microtubules in Myoblasts and Contributes to Myoblast Differentiation

Background: Skeletal muscle myoblast differentiation and fusion into multinucleate myotubes is associated with dramatic cytoskeletal changes. We find that microtubules in differentiated myotubes are highly stabilized, but premature microtubule stabilization blocks differentiation. Factors responsible for microtubule destabilization in myoblasts have not been identified. Findings: We find that a transient decrease in microtubule stabilization early during myoblast differentiation precedes the ultimate microtubule stabilization seen in differentiated myotubes. We report a role for the serine-threonine kinase LKB1 in both microtubule destabilization and myoblast differentiation. LKB1 overexpression reduced microtubule elongation in a Nocodazole washout assay, and LKB1 RNAi increased it, showing LKB1 destabilizes microtubule assembly in myoblasts. LKB1 levels and activity increased during myoblast differentiation, along with activation of the known LKB1 substrates AMPactivated protein kinase (AMPK) and microtubule affinity regulating kinases (MARKs). LKB1 overexpression accelerated differentiation, whereas RNAi impaired it. Conclusions: Reduced microtubule stability precedes myoblast differentiation and the associated ultimate microtubule stabilization seen in myotubes. LKB1 plays a positive role in microtubule destabilization in myoblasts and in myoblast differentiation. This work suggests a model by which LKB1-induced microtubule destabilization facilitates the cytoskeleta

High prevalence of germline STK11 mutations in Hungarian Peutz-Jeghers Syndrome patients

<p>Abstract</p> <p>Background</p> <p>Peutz-Jeghers syndrome (PJS) is a rare autosomal dominantly inherited disease characterized by gastrointestinal hamartomatous polyposis and mucocutaneous pigmentation. The genetic predisposition for PJS has been shown to be associated with germline mutations in the <it>STK11</it>/<it>LKB1 </it>tumor suppressor gene. The aim of the present study was to characterize Hungarian PJS patients with respect to germline mutation in <it>STK11</it>/<it>LKB1 </it>and their association to disease phenotype.</p> <p>Methods</p> <p>Mutation screening of 21 patients from 13 PJS families were performed using direct DNA sequencing and multiplex ligation-dependent probe amplification (MLPA). Comparative semi-quantitative sequencing was applied to investigate the mRNA-level effects of nonsense and splice-affecting mutations.</p> <p>Results</p> <p>Thirteen different pathogenic mutations in <it>STK11</it>, including a high frequency of large genomic deletions (38%, 5/13), were identified in the 13 unrelated families studied. One of these deletions also affects two neighboring genes (<it>SBNO2 </it>and <it>GPX4</it>), located upstream of <it>STK11</it>, with a possible modifier effect. The majority of the point mutations (88%, 7/8) can be considered novel. Quantification of the <it>STK11 </it>transcript at the mRNA-level revealed that the expression of alleles carrying a nonsense or frameshift mutation was reduced to 30-70% of that of the wild type allele. Mutations affecting splice-sites around exon 2 displayed an mRNA processing pattern indicative of co-regulated splicing of exons 2 and 3.</p> <p>Conclusions</p> <p>A combination of sensitive techniques may assure a high (100%) <it>STK11 </it>mutation detection frequency in PJS families. Characterization of mutations at mRNA level may give a deeper insight into the molecular consequences of the pathogenic mutations than predictions made solely at the genomic level.</p