Disease relevance of SPINK5

• Genes implicated so far in atopic dermatitis are SPINK5, FcepsilonRI-beta and PHF11 [1].
• It is strongly expressed in differentiated keratinocytes in normal skin but expression is markedly reduced or absent in Netherton syndrome (NS), a severe ichthyosis caused by SPINK5 mutations [2].
• SPINK5: both rare and common skin disease [3].
• METHODS: In an infant with extensive erythroderma, peeling skin and failure to thrive, we analyzed the SPINK5 gene for pathogenic mutations by direct DNA sequencing and performed repeated brain MRI studies with diffusion-weighted imaging [4].
• We showed that LEKTI is a potent inhibitor of a family of serine proteinases involved in extracellular matrix remodeling and its expression is downregulated in head and neck squamous cell carcinomas [5].

High impact information on SPINK5

• We have identified six coding polymorphisms in SPINK5 (Table 1) and found that a Glu420-->Lys variant shows significant association with atopy and AD in two independent panels of families [6].
• The gene underlying Netherton disease (SPINK5) encodes a 15-domain serine proteinase inhibitor (LEKTI) which is expressed in epithelial and mucosal surfaces and in the thymus [6].
• Mutations in SPINK5, encoding a serine protease inhibitor, cause Netherton syndrome [7].
• Netherton syndrome (NS) is a human autosomal recessive skin disease caused by mutations in the SPINK5 gene, which encodes the putative proteinase inhibitor LEKTI [8].
• However, adhesion to the human epithelial cell line HeLa S3 did not differ for these two candidal species: specific adhesion was highest for C. albicans at 44.0 +/- 1.8%, and only slightly lower for C. tropicalis at 38.8 +/- 3.6% (P = NS) [9].

Chemical compound and disease context of SPINK5

• In this report, we present purification and partial amino acid sequence of LEKTI, a serine proteinase inhibitor, and DAN (NO3) zinc-finger protein, a tumor suppressor protein of neuroblastoma, from human keratinocyte conditioned medium [10].
• We have shown previously that the core of p94 comprising NS, domains I and II, and IS1 is stable as a recombinant protein in the absence of Ca(2+) and undergoes autolysis in its presence [11].

Biological context of SPINK5

• We used heteroduplex analysis followed by direct DNA sequencing to screen all 33 exons and flanking intronic sequences of SPINK5 in the affected individuals of our cohort [12].
• Seven patients were homozygotes, eight were compound heterozygotes, and five were heterozygotes with only one identifiable SPINK5 mutation [13].
• Northern blot analysis showed variable reduction of SPINK5 mutant transcript levels, suggesting variable efficiency of nonsense-mediated mRNA decay [13].
• We studied the possible association of the SPINK5 gene for the development of atopic diseases by determining the genotypes of five polymorphisms in a Japanese population [14].
• CONCLUSION: Our results confirm that early truncation mutations of the coding sequence of SPINK5 produce a severe phenotype and that generalized peeling skin is one of the manifestations of NTS [4].

Anatomical context of SPINK5

• The Comèl-Netherton syndrome region harbors the SPINK5 gene, which encodes a multidomain serine protease inhibitor (LEKTI) predominantly expressed in epithelial and lymphoid tissues [12].
• Deletion of the N-terminal signal peptide of pro-LEKTI caused altered distribution of LEKTI from endoplasmic reticulum (ER) to cytoplasm and markedly reduced its stability, consistent with its failure to become secreted into the medium [5].
• A significant proportion of both PBC patients and controls showed T-cell responses to whole PDC (12 of 24 vs. 24 of 48 SI > 2.5 P = NS) and E1 (15 of 24 vs. 25 of 48 P = NS) [15].
• Most of the NS3 processed from NS delta 4A was localized in the cytosol fraction and was degraded promptly [16].
• Insulin-like growth factor I (IGF-I) caused a dose-dependent inhibition of 11betaHSD1 activity in sc [49.7 +/- 15.0% (IGF-I, 100 ng/ml]; P < 0.05 vs. control (100%)] and omental [71.6 +/- 7.5 (IGF-I, 100 ng/ml); P < 0.01 vs. control (100%)] stromal cells, but not in human hepatocytes [101.8 +/- 15.7% (IGF-I, 100 ng/ml); P = NS vs. control (100%)] [17].

Associations of SPINK5 with chemical compounds

• Coexpression of various KLK and SPINK5 mRNA suggests that their proteins are the candidates to balance and maintain serine protease activities in both the skin and appendages [18].
• AIMS OF THE STUDY: Development of a high throughput assay to analyse the polymorphism G1258A (Glu420Lys) in exon 14 of the SPINK5 gene followed by the validation using samples of 235 latex-allergic health care workers (HCWs) with (N=63) and without asthma (N=172), and 80 non-atopic controls [19].
• This calcium-dependent cysteine protease resembles the large subunit of m-calpain but with three unique additional sequences: an N-terminal region (NS), and two insertions (IS1 and IS2) [11].
• Recurrent disease developed in 34% of patients concurrently treated with cyclosporine and in 28% of those treated with prednisone and azathioprine alone (NS) [20].
• The cytologic examination of NS, accompanying the nasal challenge with allergen, appears therefore to be a valuable supplementary diagnostic parameter for the LNR and a promising model for further immunologic and clinical studies of the LNR [21].

Regulatory relationships of SPINK5

• Inhibitors of furin lead to enhanced secretion of unprocessed LEKTI, suggesting that processing was not required for secretion [5].

Other interactions of SPINK5

• In situ hybridization revealed intense expression of all KLK mRNA studied except KLK12 mRNA in the stratum granulosum of normal epidermis, where SPINK5 mRNA coexisted [18].
• Collectively, these results suggest that in normal skin the LG system transports and secretes LEKTI earlier than KLK7 and KLK5 preventing premature loss of stratum corneum integrity/cohesion [2].
• Our study indicates that multiple KLKs may participate in desquamation through cleavage of desmoglein 1 and regulation by LEKTI [22].
• Recently, we identified SPINK5, which encodes the serine protease inhibitor Kazal-type 5 protein (LEKTI), as the defective gene in Netherton syndrome [13].
• In addition, in vitro cleavage of the recombinant 145 kDa precursor by furin generated C-terminal fragments of 65 and 68 kDa, further supporting the involvement of furin in LEKTI processing [23].

Analytical, diagnostic and therapeutic context of SPINK5

• The spectrum of pathogenic mutations in SPINK5 in 19 families with Netherton syndrome: implications for mutation detection and first case of prenatal diagnosis [12].
• Sequence analyses of SPINK5 in seven NTS patients from five different families allowed us to identify two known and three novel mutations all creating premature termination codons [24].
• Here we describe the intron-exon organization of the gene and characterize the SPINK5 mutations in patients from 21 families of different geographic origin, using denaturing high performance liquid chromatography and direct sequencing [13].
• Rapid detection of the SPINK5 polymorphism Glu420Lys by real-time PCR technology [19].
• The temperatures in the melting analysis of the SPINK5 exon 14 PCR product were characteristic to the probes hybridised to the mutant (AA) at 51.5 degrees C and to the wild-type (GG) at 59.5 degrees C. The fast and reliable mutation detection in the tested samples makes this high-speed method suitable for larger epidemiological studies [19].

References