Project description:Autosomal recessive congenital ichthyosis (ARCI) is a group of rare inherited skin disorders characterized by remarkable hyperkeratosis. Transglutaminase 1 (TGM1) mutations have been reported to be involved in four different phenotypes of ARCI, including lamellar ichthyosis (LI), non-bullous congenital ichthyosiform erythroderma (NBCIE), bathing suit ichthyosis (BSI), and self-improving collodion ichthyosis (SICI) according to the clinical presentation and histopathology. TGM1 has been found as a defective gene in a large amount of patients with LI and some patients with NBCIE, BSI and SICI. To further understand the effect of TGM1 mutations in epidermal cells development, we performed the transcriptome analysis of HEK293T and HaCaT cells transfected with TGM1 shRNA, TGM1 wild-type and mutant clones. The transcriptomic analysis revealed the effects of TGM1 on cell-cell interaction by suppressing genes involved in the gap junctions, tight junctions and desmosomes. These findings suggested that the TGM1 deficiency disturbed the balance of keratinocytes proliferation and differentiation processes and impaired the epithelial barrier function. The results provided the basis for further understanding on the etiology of ARCI. To explore the functional impacts on some of the TGM1mutations identified, we cloned and transfected the TGM1 wild type and mutant clones into HEK293T and HaCaT cells. R142C and R348X sequence mutations observed in ARCI (Autosomal recessive congenital ichthyosis) patients were generated. The shRNA targeting TGM1 and a scrambled negative control were obtained from Invitrogen (Carlsbad, CA). The293T and HaCaT cells were transfected with over-expression clones carry either wild-type or mutated TGM1sequence. Cells were harvested 48 hours post-transfection.
Project description:Autosomal recessive congenital ichthyoses (ARCI) are a group of non-syndromic congenital keratinization disorders including harlequin ichthyosis, lamellar ichthyosis, and congenital ichthyosiform erythroderma with a total prevalence of 1:200,000. Affected individuals who are often born as collodion babies present with generalized scaling of the skin. This reflects a physical compensation for the defective cutaneous permeability barrier underlying all ichthyoses. Inactivity of 12R-lipoxygenase (12R-LOX) is a frequent cause of ARCI. Epidermis-specific conditional knockout of Alox12b encoding 12R-LOX was established in mice using the Cre-Lox system. Tamoxifen-induced Alox12b inactivation in mouse skin caused an ichthyosis-like phenotype. We used microarray to compare the gene expression profile in the epidermis of mice after tamoxifen induced Alox12b inactivation with that of control animals. Inactivation of Alox12b was associated with the upregulation of genes involved in keratinization, cholesterol biosynthesis, and Fc-epsilon receptor signaling.
Project description:Autosomal recessive congenital ichthyosis (ARCI) is a group of rare inherited skin disorders characterized by remarkable hyperkeratosis. Transglutaminase 1 (TGM1) mutations have been reported to be involved in four different phenotypes of ARCI, including lamellar ichthyosis (LI), non-bullous congenital ichthyosiform erythroderma (NBCIE), bathing suit ichthyosis (BSI), and self-improving collodion ichthyosis (SICI) according to the clinical presentation and histopathology. TGM1 has been found as a defective gene in a large amount of patients with LI and some patients with NBCIE, BSI and SICI. To further understand the effect of TGM1 mutations in epidermal cells development, we performed the transcriptome analysis of HEK293T and HaCaT cells transfected with TGM1 shRNA, TGM1 wild-type and mutant clones. The transcriptomic analysis revealed the effects of TGM1 on cell-cell interaction by suppressing genes involved in the gap junctions, tight junctions and desmosomes. These findings suggested that the TGM1 deficiency disturbed the balance of keratinocytes proliferation and differentiation processes and impaired the epithelial barrier function. The results provided the basis for further understanding on the etiology of ARCI.
Project description:Autosomal recessive congenital ichthyoses are a group of non-syndromic congenital keratinization disorders including harlequin ichthyosis, lamellar ichthyosis, and congenital ichthyosiform erythroderma with a total prevalence of 1:200,000. Affected individuals who are often born as collodion babies present with generalized scaling of the skin. This reflects a physical compensation for the defective cutaneous permeability barrier underlying all ichthyoses. Inactivity of 12R-lipoxygenase (12R-LOX) is a frequent cause of ARCI. Mice with targeted inactivation of the 12R-LOX gene Alox12b were established .Heterozygous mutant mice (Alox12b+/−) were bred with 129S6, and their heterozygous offspring were intercrossed to obtain homozygous mutant mice. Homozygous Alox12b knockout mice died within 3 hours after birth owing to defective skin barrier function. We used microarray to compare the gene expression profile in the epidermis of Alox12b-null mice with that of wildtype animals. Inactivation of Alox12b was associated with the upregulation of genes involved in keratinization, cholesterol biosynthesis, and Fc-epsilon receptor signaling.
Project description:TRIP4 is one of the subunits of the transcriptional coregulator ASC-1, a ribonucleoprotein complex that participates in transcriptional coactivation and RNA processing events. Recessive variants in the TRIP4 gene have been associated with spinal muscular atrophy with bone fractures as well as a severe form of congenital muscular dystrophy. Here we present the diagnostic journey of a patient with cerebellar hypoplasia and spinal muscular atrophy (PCH1) and congenital bone fractures. Initial exome sequencing analysis revealed no candidate variants. Reanalysis of the exome data by inclusion in the Solve-RD project resulted in the identification of a homozygous stop-gain variant in the TRIP4 gene, previously reported as disease-causing. This highlights the importance of analysis reiteration and improved and updated bioinformatic pipelines. Proteomic profile of the patient’s fibroblasts showed altered RNA-processing and impaired exosome activity supporting the pathogenicity of the detected variant. In addition, we identified a novel genetic form of PCH1, further strengthening the link of this characteristic phenotype with altered RNA metabolism.
Project description:The cornified outer layer of epidermis (stratum corneum) is our major extra-pulmonary barrier to the environment. This layer results from a well-orchestrated program of terminal differentiation producing corneocytes filled primarily with keratin intermediate filaments tightly connected by disulfide bonding. This cytoskeleton is interconnected to an isopeptide cross-linked protein envelope at the cell periphery stabilized by transglutaminase cross-linking.The envelope serves as a scaffold for deposition of the lipid barrier containing w-OH-ceramides secreted from inside the maturing keratinocytes.That defects in the transglutaminase gene TGM1 are a major cause of autosomal recessive congenital ichthyosis testifies to the importance of proper envelope formation for barrier function.
Project description:Autosomal recessive congenital ichthyosis (ARCI) is a heterogeneous group of monogenic skin disorders caused by mutations in any of >10 different genes, many of which are involved in epidermal synthesis of ω-O-acylceramides (acylCer), an essential precursor of the corneocyte lipid envelope that is also dependent on transglutaminase-1 for normal skin barrier formation. We hypothesized that inactivating TGM1 mutations, the most common cause of ARCI, might lead to a compensatory overexpression of transcripts involved in barrier repair, including ARCI-causing genes. Using microarray we examined the global mRNA expression profile in skin biopsies from five ARCI-patients with TGM1 mutations and four healthy controls. There were a total of 602 differentially expressed genes (adjusted P<0.05). Gene ontology analysis showed enrichment of mRNA encoding proteins associated with biological pathways mainly involved in keratinocyte differentiation and adaptive/innate immune response. Moreover, among non-syndromic ARCI-causing genes, seven out of twelve were significantly increased (log2fold -change=0.98-2.05). Four genes causing syndromic ichthyosis and seven other genes involved in biosynthesis of fatty acyl-CoA and ceramides were also significantly affected. This study reveals upregulation of several ichthyosis-causing genes in the skin of patients with TGM1 mutations, indicating a compensatory induction of acylCer biosynthesis as a part of a barrier repair mechanism.
Project description:Infantile neuroaxonal dystrophy (INAD) is an ultra-rare early-onset autosomal recessive neurodegenerative disorder due to PLA2G6 variants. Copy number analysis of SNP arrays was performed on one INAD patient sample.