title: Identification and functional characterization of a novel transglutaminase 1 gene mutation associated with autosomal recessive congenital ichthyosis.
abstract: BACKGROUND
  Autosomal recessive congenital ichthyosis (ARCI) is a group of genetically heterogeneous diseases. Mutations in transglutaminase (TGase) 1 gene (TGM1, OMIM 190195) have been implicated in ARCI. However, little is known about TGM1 mutations in the Chinese population, and no functional studies have investigated the biological effect of mutant TGM1 on human epidermal keratinocytes (HaCaT) cells.
  
  
  OBJECTIVE
  To identify the pathogenic mutations of TGM1 gene in two Chinese siblings with ARCI and gain insight into functional consequences of these mutations.
  
  
  METHODS
  Fifteen exons and flanking splice sites of TGM1 gene were amplified by polymerase chain reaction and then underwent bidirectional Sanger sequencing. The HaCaT cells were transfected with lentiviral vectors, which overexpressed either wild-type or mutant TGM1 cDNAs with deleted homeodomain. Cell proliferation and cell cycle progression were detected. The expression of cyclin D1, cyclin B1, CDK4, TGM1, K10, involucrin, and filaggrin proteins were investigated by Western blot analysis.
  
  
  RESULTS
  We found two compound heterozygous missense mutations (c.515C>T, R143C in exon 3 and c.759C>T, S212F in exon 4) in both siblings. HaCaT cells transfected with mutant TGM1 cDNAs displayed a lower growth rate and delayed S phase while overexpression of wild-type TGM1 cDNAs led to accelerated growth. HaCaT cells transfected with mutant TGM1 cDNAs displayed lower expression of differentiation markers such as involucrin and filaggrin. Our findings suggest that the compound heterozygous missense (c.515C>T, R143C) mutations in exon 3 and missense (c.759C>T, S212F) mutations in exon 4 result in the phenotype of ARCI. TGM1 mutations can suppress keratinocyte growth and cornified cell envelope formation.
authors.affiliation: Department of Dermatology, Guangzhou Institute of Dermatology, Guangzhou, China.
authors.forename: San-Quan
authors.initials: SQ
authors.lastname: Zhang
authors.affiliation: Department of Dermatology, Nanfang Hospital, South Medical University, Guangzhou, China.|Department of Dermatology, Dongguan Institute of Dermatology, Dongguan, China.
authors.forename: Chang-Xing
authors.initials: CX
authors.lastname: Li
authors.affiliation: Department of Dermatology, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors.forename: Xin-Qian
authors.initials: XQ
authors.lastname: Gao
authors.affiliation: Department of Dermatology, Guangdong Sian Hospital, Dongguan, Guangdong Province, China.
authors.forename: Wen-Yuan
authors.initials: WY
authors.lastname: Qiu
authors.affiliation: Department of Dermatology, Guangzhou Institute of Dermatology, Guangzhou, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Chen
authors.affiliation: Department of Dermatology, Guangzhou Women and Children's Medical Center, Guangzhou, China.
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Li
authors.affiliation: Department of Dermatology, Guangzhou Institute of Dermatology, Guangzhou, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Dermatology, Guangzhou Institute of Dermatology, Guangzhou, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Tian
authors.affiliation: Department of Dermatology, Guangzhou Institute of Dermatology, Guangzhou, China.
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Tang
authors.affiliation: Department of Dermatology, Guangzhou Institute of Dermatology, Guangzhou, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Zhao
authors.affiliation: Department of Dermatology, Guangzhou Institute of Dermatology, Guangzhou, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Department of Dermatology, Guangzhou Institute of Dermatology, Guangzhou, China.
authors.forename: Xi-Bao
authors.initials: XB
authors.lastname: Zhang
mesh_terms: D044466:Asian People / Q000235:genetics; D002460:Cell Line; D049109:Cell Proliferation / Q000235:genetics; D002648:Child; D002681:China; D005091:Exons / Q000235:genetics; D005260:Female; D000091344:Filaggrin Proteins; D005808:Genes, Recessive; D006579:Heterozygote; D006801:Humans; D016113:Ichthyosiform Erythroderma, Congenital / Q000235:genetics* / Q000473:pathology; D007381:Intermediate Filament Proteins / Q000378:metabolism; D015603:Keratinocytes / Q000502:physiology; D008297:Male; D020125:Mutation, Missense; D010375:Pedigree; D011498:Protein Precursors / Q000378:metabolism; D059807:S Phase Cell Cycle Checkpoints / Q000235:genetics; D014162:Transfection; D011503:Transglutaminases / Q000235:genetics*
chemical_list: C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D011498:Protein Precursors; C032253:involucrin; D011503:Transglutaminases; C105804:transglutaminase 1