Project description:Spinocerebellar Ataxia Type 2 (SCA2) is caused by expansion of a polyglutamine encoding triplet repeat in the human ATXN2 gene beyond (CAG)31. This is thought to mediate toxic gain-of-function by protein aggregation, and affect RNA processing, resulting in degenerative processes affecting preferentially cerebellar neurons. As a faithful animal model, we generated a knock-in mouse replacing the single CAG of murine Atxn2 with CAG42, a frequent patient genotype. This expansion size was inherited stably. The mice showed phenotypes with reduced weight and later motor incoordination. Although brain Atxn2 mRNA became elevated, soluble ATXN2 protein levels diminished over time, which might explain partial loss-of-function effects. Deficits in soluble ATXN2 protein correlated with the appearance of insoluble ATXN2, a progressive feature in cerebellum possibly reflecting toxic gains-of-function. Since in vitro ATXN2 overexpression was known to reduce levels of its protein interactor PABPC1, we studied expansion effects on PABPC1. In cortex, PABPC1 transcript, soluble and insoluble protein levels were increased. In more vulnerable cerebellum the progressive insolubility of PABPC1 was accompanied by decreased soluble protein levels, with PABPC1 mRNA showing no compensatory increase. The sequestration of PABPC1 into insolubility by ATXN2 function gains was validated in human cell culture. To understand consequences on mRNA processing, transcriptome profiles at medium and old age in three different tissues were studied and demonstrated selective induction of Fbxw8 in old cerebellum. Fbxw8 is encoded next to the Atxn2 locus and was shown in vitro to decrease the level of expanded insoluble ATXN2 protein. In conclusion, our data support the concept that expanded ATXN2 undergoes progressive insolubility and affects PABPC1 by a toxic gain-of-function mechanism with tissue-specific effects, which may be partially alleviated by the induction of FBXW8. Factorial design comparing Atxn2 knock-in mice with wild type littermates in three different tissues (brainstem, cerebellum, liver)
Project description:Spinocerebellar Ataxia Type 2 (SCA2) is caused by expansion of a polyglutamine encoding triplet repeat in the human ATXN2 gene beyond (CAG)31. This is thought to mediate toxic gain-of-function by protein aggregation, and affect RNA processing, resulting in degenerative processes affecting preferentially cerebellar neurons. As a faithful animal model, we generated a knock-in mouse replacing the single CAG of murine Atxn2 with CAG42, a frequent patient genotype. This expansion size was inherited stably. The mice showed phenotypes with reduced weight and later motor incoordination. Although brain Atxn2 mRNA became elevated, soluble ATXN2 protein levels diminished over time, which might explain partial loss-of-function effects. Deficits in soluble ATXN2 protein correlated with the appearance of insoluble ATXN2, a progressive feature in cerebellum possibly reflecting toxic gains-of-function. Since in vitro ATXN2 overexpression was known to reduce levels of its protein interactor PABPC1, we studied expansion effects on PABPC1. In cortex, PABPC1 transcript, soluble and insoluble protein levels were increased. In more vulnerable cerebellum the progressive insolubility of PABPC1 was accompanied by decreased soluble protein levels, with PABPC1 mRNA showing no compensatory increase. The sequestration of PABPC1 into insolubility by ATXN2 function gains was validated in human cell culture. To understand consequences on mRNA processing, transcriptome profiles at medium and old age in three different tissues were studied and demonstrated selective induction of Fbxw8 in old cerebellum. Fbxw8 is encoded next to the Atxn2 locus and was shown in vitro to decrease the level of expanded insoluble ATXN2 protein. In conclusion, our data support the concept that expanded ATXN2 undergoes progressive insolubility and affects PABPC1 by a toxic gain-of-function mechanism with tissue-specific effects, which may be partially alleviated by the induction of FBXW8.
Project description:Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disorder, which is caused by an unstable CAG-repeat expansion in the SCA2 gene, that encodes a polyglutamine tract (polyQ-tract) expansion in ataxin-2 protein (ATXN2). The RNA-binding protein ATXN2 interacts with the poly(A)-binding protein PABPC1, localizing to ribosomes at the rough endoplasmic reticulum or to polysomes. Under cell stress ATXN2 and PABPC1 show redistribution to stress granules where mRNAs are kept away from translation and from degradation. It is unknown whether ATXN2 associates preferentially with specific mRNAs or how it modulates their processing. Here, we investigated Atxn2 knock-out (Atxn2-/-) mouse liver, cerebellum and midbrain regarding their RNA profile, employing oligonucleotide microarrays for screening and RNA deep sequencing for validation. Modest ~1.4-fold upregulations were observed for the level of many mRNAs encoding ribosomal proteins and other translation pathway factors. Quantitative reverse transcriptase PCR and immunoblots in liver tissue confirmed these effects and demonstrated an inverse correlation also with PABPC1 mRNA and protein. ATXN2 deficiency also enhanced phosphorylation of the ribosomal protein S6, while impairing the global protein synthesis rate, suggesting a block between the enhanced translation drive and the impaired execution. Furthermore, ATXN2 overexpression and deficiency retarded cell cycle progression. ATXN2 mRNA levels showed a delayed phasic twofold increase under amino acid and serum starvation, similar to ATXN3, but different from motor neuron disease genes MAPT and SQSTM1. ATXN2 mRNA levels depended particularly on mTOR signalling. Altogether the data implicate ATXN2 in the adaptation of mRNA translation and cell growth to nutrient availability and stress. Factorial design comparing ataxin-2 knock-out mice with wild type littermates in three different tissues (midbrain, cerebellum, liver) and 3 different ages.
Project description:Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disorder, caused by an unstable CAG-repeat expansion in the SCA2 gene, which encodes a polyglutamine (polyQ) domain expansion in the protein ataxin-2 (ATXN2). The RNA-binding protein ATXN2 interacts with the poly(A)-binding protein PABPC1, localizing to ribosomes in the rough endoplasmic reticulum or in polysomes. Under cell stress ATXN2 and PABPC1 are relocated to stress granules where mRNAs are protected from translation and from degradation. It is unknown whether ATXN2 associates preferentially with specific mRNAs or how it modulates their processing. Here, we investigated the RNA profile of liver and cerebellum from adult Atxn2 knock-out (Atxn2-/-) mice, employing oligonucleotide microarrays for screening and RNA deep sequencing for validation. We consistently observed modest upregulations for the level of many mRNAs encoding proteins of the ribosomal large and small subunit as well as the translation initiation complex. Quantitative reverse transcriptase PCR in liver tissue confirmed these upregulations for the ribosomal components Rpl14, Rpl18, Rps10, Rps18, Gnb2l1, the translation initiation factors Eif2s2, Eif3s6, Pabpc1, and the ribosomal biogenesis modulator Nop10. Quantitative immunoblots substantiated the effects for PABPC1. Thus, the physiological role of ATXN2 modifies the abundance of cellular translation factors.
Project description:Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disorder, which is caused by an unstable CAG-repeat expansion in the SCA2 gene, that encodes a polyglutamine tract (polyQ-tract) expansion in ataxin-2 protein (ATXN2). The RNA-binding protein ATXN2 interacts with the poly(A)-binding protein PABPC1, localizing to ribosomes at the rough endoplasmic reticulum or to polysomes. Under cell stress ATXN2 and PABPC1 show redistribution to stress granules where mRNAs are kept away from translation and from degradation. It is unknown whether ATXN2 associates preferentially with specific mRNAs or how it modulates their processing. Here, we investigated Atxn2 knock-out (Atxn2-/-) mouse liver, cerebellum and midbrain regarding their RNA profile, employing oligonucleotide microarrays for screening and RNA deep sequencing for validation. Modest ~1.4-fold upregulations were observed for the level of many mRNAs encoding ribosomal proteins and other translation pathway factors. Quantitative reverse transcriptase PCR and immunoblots in liver tissue confirmed these effects and demonstrated an inverse correlation also with PABPC1 mRNA and protein. ATXN2 deficiency also enhanced phosphorylation of the ribosomal protein S6, while impairing the global protein synthesis rate, suggesting a block between the enhanced translation drive and the impaired execution. Furthermore, ATXN2 overexpression and deficiency retarded cell cycle progression. ATXN2 mRNA levels showed a delayed phasic twofold increase under amino acid and serum starvation, similar to ATXN3, but different from motor neuron disease genes MAPT and SQSTM1. ATXN2 mRNA levels depended particularly on mTOR signalling. Altogether the data implicate ATXN2 in the adaptation of mRNA translation and cell growth to nutrient availability and stress.
Project description:To describe the protein profile in hippocampus, colon and ileum tissue’ changing after the old faeces transplants, we adopted a quantitative label free proteomics approach.
Project description:We collected whole genome testis expression data from hybrid zone mice. We integrated GWAS mapping of testis expression traits and low testis weight to gain insight into the genetic basis of hybrid male sterility.
Project description:The aim of the study was to investigate whether the trefoil peptide genes, in concerted action with a miRNA regulatory network, were contributing to nutritional maintrenance. Using a Tff3 knock-out mouse model, 21 specific miRNAs were noted to be significantly deregulated when compared to the wild type strain.