A PKC-Dependent Recruitment of MMP-2 Controls Semaphorin-3A Growth-Promoting Effect in Cortical Dendrites

There is increasing evidence for a crucial role of proteases and metalloproteinases during axon growth and guidance. In this context, we recently described a functional link between the chemoattractive Sema3C and Matrix metalloproteinase 3 (MMP3). Here, we provide data demonstrating the involvement of MMP-2 to trigger the growth-promoting effect of Sema3A in cortical dendrites. The in situ analysis of MMP-2 expression and activity is consistent with a functional growth assay demonstrating in vitro that the pharmacological inhibition of MMP-2 reduces the growth of cortical dendrites in response to Sema3A. Hence, our results suggest that the selective recruitment and activation of MMP-2 in response to Sema3A requires a PKC alpha dependent mechanism. Altogether, we provide a second set of data supporting MMPs as effectors of the growth-promoting effects of semaphorins, and we identify the potential signalling pathway involved

Identification of variants in MBNL1 in patients with a myotonic dystrophy-like phenotype

The myotonic dystrophies (DMs) are the most common inherited muscular disorders in adults. In most of the cases, the disease is caused by (CTG)(n)/(CCTG)(n) repeat expansions (EXPs) in non-coding regions of the genes DMPK (dystrophia myotonica-protein kinase) and CNBP (CCHC-type zinc-finger nucleic acid-binding protein). The EXP is transcribed into mutant RNAs, which provoke a common pathomechanism that is characterized by misexpression and mis-splicing. In this study, we screened 138 patients with typical clinical features of DM being negative for EXP in the known genes. We sequenced DMPK and CNBP associated with DM, as well as CELF1 (CUGBP, Elav-like family member 1) and MBNL1 (muscleblind-like splicing regulator 1) associated with the pathomechanism of DM, for pathogenic variants, addressing the question whether defects in other genes could cause a DM-like phenotype. We identified variants in three unrelated patients in the MBNL1 gene, two of them were heterozygous missense mutations and one an in-frame deletion of three amino acids. The variants were located in different conserved regions of the protein. The missense mutations were classified as potentially pathogenic by prediction tools. Analysis of MBNL1 splice target genes was carried out for one of the patients using RNA from peripheral blood leukocytes (PBL). Analysis of six genes known to show mis-splicing in the skeletal muscle gave no informative results on the effect of this variant when tested in PBL. The association of these variants with the DM phenotype therefore remains unconfirmed, but we hope that in view of the key role of MBNL1 in DM pathogenesis our observations may foster further studies in this direction

Additional file 3: of Genes with high penetrance for syndromic and non-syndromic autism typically function within the nucleus and regulate gene expression

Full statistical results. (DOCX 164 kb