BACKGROUND: FLNC is one of the few genes associated with all types of cardiomyopathies, but it also underlies neuromuscular phenotype. The combination of concomitant neuromuscular and cardiac involvement is not often observed in filaminopathies and the impact of this on the disease prognosis has hitherto not been analyzed. RESULTS: Here we provide a detailed clinical, genetic, and structural prediction analysis of distinct FLNC-associated phenotypes based on twelve pediatric cases. They include early-onset restrictive cardiomyopathy (RCM) in association with congenital myopathy. In all patients the initial diagnosis was established during the first year of life and in five out of twelve (41.7%) patients the first symptoms were observed at birth. RCM was present in all patients, often in combination with septal defects. No ventricular arrhythmias were noted in any of the patients presented here. Myopathy was confirmed by neurological examination, electromyography, and morphological studies. Arthrogryposes was diagnosed in six patients and remained clinically meaningful with increasing age in three of them. One patient underwent successful heart transplantation at the age of 18 years and two patients are currently included in the waiting list for heart transplantation. Two died due to congestive heart failure. One patient had ICD instally as primary prevention of SCD. In ten out of twelve patients the disease was associated with missense variants and only in two cases loss of function variants were detected. In half of the described cases, an amino acid substitution A1186V, altering the structure of IgFLNc10, was found. CONCLUSIONS: The present description of twelve cases of early-onset restrictive cardiomyopathy with congenital myopathy and FLNC mutation, underlines a distinct unique phenotype that can be suggested as a separate clinical form of filaminopathies. Amino acid substitution A1186V, which was observed in half of the cases, defines a mutational hotspot for the reported combination of myopathy and cardiomyopathy. Several independent molecular mechanisms of FLNC mutations linked to filamin structure and function can explain the broad spectrum of FLNC-associated phenotypes. Early disease presentation and unfavorable prognosis of heart failure demanding heart transplantation make awareness of this clinical form of filaminopathy of great clinical importance.

• Klíčová slova
• Childhood, Congenital myopathy, FLNC-associated phenotype, Genes, Mutation, Rare clinical phenotype, Restrictive cardiomyopathy, Unfavourable prognosis,
• MeSH
• fenotyp MeSH
• filaminy chemie   genetika   metabolismus   MeSH
• kardiomyopatie * genetika   metabolismus   MeSH
• lidé MeSH
• nemoci svalů * MeSH
• restriktivní kardiomyopatie * genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• filaminy MeSH

Actin-associated proteins regulate multiple cellular processes, including proliferation and differentiation, but the molecular mechanisms underlying these processes are unclear. Here, we report that the actin-binding protein filamin A (FlnA) physically interacts with the actin-nucleating protein formin 2 (Fmn2). Loss of FlnA and Fmn2 impairs proliferation, thereby generating multiple embryonic phenotypes, including microcephaly. FlnA interacts with the Wnt co-receptor Lrp6. Loss of FlnA and Fmn2 impairs Lrp6 endocytosis, downstream Gsk3β activity, and β-catenin accumulation in the nucleus. The proliferative defect in Flna and Fmn2 null neural progenitors is rescued by inhibiting Gsk3β activity. Our findings thus reveal a novel mechanism whereby actin-associated proteins regulate proliferation by mediating the endocytosis and transportation of components in the canonical Wnt pathway. Moreover, the Fmn2-dependent signaling in this pathway parallels that seen in the non-canonical Wnt-dependent regulation of planar cell polarity through the Formin homology protein Daam. These studies provide evidence for integration of actin-associated processes in directing neuroepithelial proliferation.

• Klíčová slova
• Differentiation, Endocytosis, Filamin, Formin, Lrp6, Neural progenitor, Proliferation, Vesicle trafficking,
• MeSH
• beta-katenin metabolismus   MeSH
• buněčná diferenciace MeSH
• buněčná membrána fyziologie   MeSH
• buněčné linie MeSH
• endocytóza fyziologie   MeSH
• filaminy genetika   metabolismus   MeSH
• forminy MeSH
• HEK293 buňky MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• kinasa glykogensynthasy 3beta antagonisté a inhibitory   metabolismus   MeSH
• LDL receptor related protein 6 metabolismus   MeSH
• lidé MeSH
• mikrocefalie genetika   MeSH
• mikrofilamentové proteiny genetika   metabolismus   MeSH
• myši knockoutované MeSH
• myši MeSH
• proliferace buněk genetika   fyziologie   MeSH
• proteiny nervové tkáně MeSH
• proteiny Wnt metabolismus   MeSH
• signální dráha Wnt fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• beta-katenin MeSH
• filaminy MeSH
• FlnA protein, mouse MeSH Prohlížeč
• formin 2 protein, mouse MeSH Prohlížeč
• forminy MeSH
• jaderné proteiny MeSH
• kinasa glykogensynthasy 3beta MeSH
• LDL receptor related protein 6 MeSH
• Lrp6 protein, mouse MeSH Prohlížeč
• mikrofilamentové proteiny MeSH
• proteiny nervové tkáně MeSH
• proteiny Wnt MeSH

Filamin B (FlnB) is an actin-binding protein thought to transduce signals from various membrane receptors and intracellular proteins onto the actin cytoskeleton. Formin1 (Fmn1) is an actin-nucleating protein, implicated in actin assembly and intracellular signaling. Human mutations in FLNB cause several skeletal disorders associated with dwarfism and early bone fusion. Mouse mutations in Fmn1 cause aberrant fusion of carpal digits. We report here that FlnB and Fmn1 physically interact, are co-expressed in chondrocytes in the growth plate and share overlapping expression in the cell cytoplasm and nucleus. Loss of FlnB leads to a dramatic decrease in Fmn1 expression at the hypertrophic-to-ossification border. Loss of Fmn1-FlnB in mice leads to a more severe reduction in body size, weight and growth plate length, than observed in mice following knockout of either gene alone. Shortening of the long bone is associated with a decrease in chondrocyte proliferation and an overall delay in ossification in the double-knockout mice. In contrast to FlnB null, Fmn1 loss results in a decrease in the width of the prehypertrophic zone. Loss of both proteins, however, causes an overall decrease in the width of the proliferation zone and an increase in the differentiated hypertrophic zone. The current findings suggest that Fmn1 and FlnB have shared and independent functions. FlnB loss promotes prehypertrophic differentiation whereas Fmn1 leads to a delay. Both proteins, however, regulate chondrocyte proliferation, and FlnB may regulate Fmn1 function at the hypertrophic-to-ossification border, thereby explaining the overall delay in ossification.

• MeSH
• buněčná diferenciace * MeSH
• chondrocyty metabolismus   patologie   MeSH
• fetální proteiny nedostatek   metabolismus   MeSH
• filaminy nedostatek   metabolismus   MeSH
• forminy MeSH
• fyziologická kalcifikace MeSH
• hypertrofie MeSH
• jaderné proteiny nedostatek   metabolismus   MeSH
• lidé MeSH
• mikrofilamentové proteiny nedostatek   metabolismus   MeSH
• myši knockoutované MeSH
• proliferace buněk MeSH
• receptor parathormonu typ 1 metabolismus   MeSH
• růstová ploténka metabolismus   patologie   MeSH
• transport proteinů MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• fetální proteiny MeSH
• filaminy MeSH
• forminy MeSH
• jaderné proteiny MeSH
• mikrofilamentové proteiny MeSH
• receptor parathormonu typ 1 MeSH