Protein phosphatase 2A (PP2A)-specific ubiquitin ligase MID1 is a sequence-dependent regulator of translation efficiency controlling 3-phosphoinositide-dependent protein kinase-1 (PDPK-1).

We have shown previously that the ubiquitin ligase MID1, mutations of which cause the midline malformation Opitz BBB/G syndrome (OS), serves as scaffold for a microtubule-associated protein complex that regulates protein phosphatase 2A (PP2A) activity in a ubiquitin-dependent manner. Here, we show that the MID1 protein complex associates with mRNAs via a purine-rich sequence motif called MIDAS (MID1 association sequence) and thereby increases stability and translational efficiency of these mRNAs. Strikingly, inclusion of multiple copies of the MIDAS motif into mammalian mRNAs increases production of the encoded proteins up to 20-fold.

Biguanide metformin acts on tau phosphorylation via mTOR/protein phosphatase 2A (PP2A) signaling.

Hyperphosphorylated tau plays an important role in the formation of neurofibrillary tangles in brains of patients with Alzheimer's disease (AD) and related tauopathies and is a crucial factor in the pathogenesis of these disorders. Though diverse kinases have been implicated in tau phosphorylation, protein phosphatase 2A (PP2A) seems to be the major tau phosphatase. Using murine primary neurons from wild-type and human tau transgenic mice, we show that the antidiabetic drug metformin induces PP2A activity and reduces tau phosphorylation at PP2A-dependent epitopes in vitro and in vivo.

Severe familial left ventricular non-compaction cardiomyopathy due to a novel troponin T (TNNT2) mutation.

Aims: Left ventricular non-compaction (LVNC) is caused by mutations in multiple genes. It is still unclear whether LVNC is the primary determinant of cardiomyopathy or rather a secondary phenomenon with intrinsic cardiomyocyte dysfunction being the actual cause of the disease. Here, we describe a family with LVNC due to a novel missense mutation, pE96K, in the cardiac troponin T gene (TNNT2).

Adverse events in families with hypertrophic or dilated cardiomyopathy and mutations in the MYBPC3 gene.

Background: Mutations in MYBPC3 encoding myosin binding protein C belong to the most frequent causes of hypertrophic cardiomyopathy (HCM) and may also lead to dilated cardiomyopathy (DCM). MYBPC3 mutations initially were considered to cause a benign form of HCM. The aim of this study was to examine the clinical outcome of patients and their relatives with 18 different MYBPC3 mutations.

Incomplete nonsense-mediated decay of mutant lamin A/C mRNA provokes dilated cardiomyopathy and ventricular tachycardia.

We have identified a family in which several members died of sudden cardiac death or suffer from dilated cardiomyopathy (DCM) and rhythm disturbances. Mutation screening revealed co-segregation of a novel nonsense mutation (pR321X) in the lamin A gene, LMNA, with the disease. Lamin A, and its smaller splice form lamin C are nuclear intermediate filament proteins forming a major part of the lamina, which is underlying the inner nuclear membrane.

Large-scale mutation screening in patients with dilated or hypertrophic cardiomyopathy: a pilot study using DGGE.

Cardiomyopathies are complex myocardial diseases characterized by inappropriate ventricular hypertrophy (HCM) or dilation (DCM). Both disorders may lead to sudden death or progressive heart failure and exhibit familial aggregation with marked genetic heterogeneity. Many candidate genes were identified by linkage analysis, experimental animal studies, and expression analysis.