Large-scale identification of human genes implicated in epidermal barrier function

gb-2007-8-6-r107 GBJ Research Large-scale identification of human genes implicated in epidermal barrier function Toulza Eve toulza@udear.cnrs.fr Mattiuzzo R Nicolas mattiuz@udear.cnrs.fr Galliano Marie-Florence galliano@udear.cnrs.fr Jonca Nathalie jonca@udear.cnrs.fr Dossat Carole cdossat@genoscope.cns.fr Jacob Daniel daniel.jacob@pmtg.u-bordeaux2.fr de Daruvar Antoine antoine.daruvar@pmtg.u-bordeaux2.fr Wincker Patrick pwincker@genoscope.cns.fr Serre Guy serre.g@chu-toulouse.fr Guerrin Marina mweber@udear.cnrs.fr

UMR 5165 "Epidermis Differentiation and Rheumatoid Autoimmunity", CNRS - Toulouse III University (IFR 30, INSERM - CNRS - Toulouse III University - CHU), allées Jules Guesde, 31073 Toulouse, France

Genoscope and CNRS UMR 8030, rue Gaston Crémieux, 91057 Evry, France

Centre de Bioinformatique Bordeaux, Université V. Segalen Bordeaux 2, rue Léo Saignat, 33076 Bordeaux Cedex, France

Genome Biology 1465-6906 2007 8 6 R107 http://genomebiology.com/2007/8/6/R107 17562024 10.1186/gb-2007-8-6-r107 1 3 2007 24 5 2007 11 6 2007 11 06 2007 2007 Toulza et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The transcriptome of granular keratinocytes

Identification of genes expressed in epidermal granular keratinocytes by ORESTES, including a number that are highly specific for these cells.

Abstract

Background

During epidermal differentiation, keratinocytes progressing through the suprabasal layers undergo complex and tightly regulated biochemical modifications leading to cornification and desquamation. The last living cells, the granular keratinocytes (GKs), produce almost all of the proteins and lipids required for the protective barrier function before their programmed cell death gives rise to corneocytes. We present here the first analysis of the transcriptome of human GKs, purified from healthy epidermis by an original approach.

Results

Using the ORESTES method, 22,585 expressed sequence tags (ESTs) were produced that matched 3,387 genes. Despite normalization provided by this method (mean 4.6 ORESTES per gene), some highly transcribed genes, including that encoding dermokine, were overrepresented. About 330 expressed genes displayed less than 100 ESTs in UniGene clusters and are most likely to be specific for GKs and potentially involved in barrier function. This hypothesis was tested by comparing the relative expression of 73 genes in the basal and granular layers of epidermis by quantitative RT-PCR. Among these, 33 were identified as new, highly specific markers of GKs, including those encoding a protease, protease inhibitors and proteins involved in lipid metabolism and transport. We identified filaggrin 2 (also called ifapsoriasin), a poorly characterized member of the epidermal differentiation complex, as well as three new lipase genes clustered with paralogous genes on chromosome 10q23.31. A new gene of unknown function, C1orf81, is specifically disrupted in the human genome by a frameshift mutation.

Conclusion

These data increase the present knowledge of genes responsible for the formation of the skin barrier and suggest new candidates for genodermatoses of unknown origin.

Bioinformatics Genome studies Cell biology

Background

High-throughput genomic projects focusing on the identification of cell- and tissue-specific transcriptomes are expected to uncover fundamental insights into biological processes. Particularly intriguing are genes in sequenced genomes that remain hypothetical and/or poorly represented in expressed sequence databases, and whose functions in health and disease remain unknown. Some of these are most probably implicated in organ-specific functions. Their characterization is essential to complete the annotation of sequenced genomes and is expected to contribute to advances in physiology and pathology. In order to achieve such goals, transcriptome studies on tissues rather than cultured cells, and eventually on a single cell type at a precise differentiation step are more likely to provide new information.

The epidermis is a highly specialized tissue mainly dedicated to the establishment of a barrier that restricts both water loss from the body and ingress of pathogens. The barrier function of the epidermis is known to involve the expression of numerous tissue-specific genes, most of which are specifically expressed in the late steps of keratinocyte differentiation. In order to establish and constantly maintain this barrier, keratinocytes undergo a complex, highly organized and tightly controlled differentiation program leading to cornification and finally to desquamation. During this process, cells migrate from the basal, proliferative layer to the surface, where they form the cornified layer (stratum corneum). According to the current model of skin epithelial maintenance, basal keratinocytes encompass a heterogeneous cell population that includes slow-cycling stem cells 1. These stem cells give rise to transiently amplifying keratinocytes that constitute most of the basal layer. They divide only a few times and finally move upward while differentiating to form the spinous layer. The proliferating compartment is characterized by the specific expression of cell cycle regulators and integrin family members responsible for the attachment of the epidermis to the basement membrane. Growth arrested keratinocytes undergo differentiation, mainly characterized by a shift in cytokeratin expression from KRT5 (keratin 5) and KRT14 in the basal layer to KRT1 and KRT10 in suprabasal layers. As differentiation progresses, keratinocytes from the spinous layers progressively express a small number of specific differentiation markers, like involucrin. However, the differentiation program culminates in the granular layer, where keratinocytes express more than 30 epidermis-specific proteins, including proteins that are stored in cytosolic granules characteristic of granular keratinocytes (GKs). These proteins include well known components of the cornified layer, like loricrin and elafin, but also recently identified ones, such as keratinocyte differentiation associated protein (KDAP), hornerin, suprabasin, keratinocyte proline rich protein (hKPRP), and so on 2345.

GKs undergo a special programmed cell death, called cornification, which gives rise to corneocytes that no longer exhibit transcriptional or translational activity and are devoid of organelles. Rather, their intracellullar content consists of a homogeneous matrix composed mainly of covalently linked keratins. The cornified envelope, a highly specialized insoluble structure, encapsulates corneocytes in place of their plasma membrane (see Kalinin et al. 6 for a recent review). The lipid-enriched extracellular matrix, which subserves the barrier, is produced by a highly active lipid factory mainly operative in the granular layer and comprises secretory organelles named the epidermal lamellar bodies 7. In addition to the provision of lipids for the barrier, lamellar bodies deliver a large number of proteins, including lipid-processing enzymes, proteases and anti-proteases that regulate desquamation, antimicrobial peptides and corneodesmosin, an adhesive protein secondarily located in the external face of the desmosomes, as they turn into corneodesmosomes 8. Therefore, the components of the stratum corneum, responsible for most of the protective cutaneous functions, are produced by GKs.

Transcriptome studies of selected cell types of the human epidermis are expected to contribute to the elucidation of the mechanisms responsible for barrier function. They will also shed further light on the causes of monogenic genodermatoses and the pathomechanisms of common complex skin disorders like psoriasis. However, present knowledge on the gene repertoire expressed by keratinocytes remains largely fragmentary. Among the approximately eight million human expressed sequence tags (ESTs) from the dbEST division of the GenBank database, only 1,210 are annotated as originating from the epidermis, although these are, in fact, derived from cultured keratinocytes, which do not fully recapitulate the complex in vivo differentiation program. In this article, we describe the results of a large-scale cDNA sequencing project on GKs of healthy human skin, purified by a new method. In order to characterize genes expressed at a low level and to avoid the repetitive sequencing of highly expressed ones, we used the ORESTES (open reading frame EST) method to prepare a large series of small size cDNA libraries using arbitrarily chosen primers for reverse transcription (RT) and PCR amplification 9. The sequencing of about 25,000 clones has produced a list of 3,387 genes expressed by GKs. Some of them, analyzed by quantitative RT-PCR, were shown to be expressed in a cell-specific manner. This effort resulted in a large number of novel candidate genes of importance for the epidermis barrier function and the etiology of genodermatoses.

Results

Purification of human granular keratinocytes

As a first step in this transcriptome project we devised a method to purify GKs. Iterative incubations of pieces of human epidermis with trypsin were performed to give three suspended cell fractions (hereafter named T1-T3) and finally to isolate cells attached to the stratum corneum (T4 fraction). Morphological analyses revealed that after three treatments, residual epidermal fragments were mostly composed of corneocytes and GKs (Figure 1). Quantitative real-time PCR was performed to quantify the enrichment in GKs. To first select a reference gene for normalization, the relative expression of eight housekeeping genes (GAPDH, SOD1, ACTB, B2M, HPRT1, HMBS, TBP and UBC) in each cell fraction (T1-T4) was analyzed using GeNorm 10. In agreement with previous data 11, beta-2-microglobulin (B2M) appeared to be stably expressed during epidermis differentiation, and was thus chosen for normalization. In addition, we used the lectin Galectin-7 (LSGAL7), which was previously shown by in situ hybridization to be equally expressed in all epidermal layers 12. BPAG2 (bullous pemphigoid antigen 2) or KRT14, and KLK7 (kallikrein 7, also called stratum corneum chymotryptic enzyme (SCCE)) were selected as specific for the basal layer or the GKs, respectively 1314. For four cell fractionations from different individuals, the mean T1/T4 expression ratio of KRT14 was 13, whereas the mean T4/T1 expression ratio of SCCE was approximately 130 (Table 1). The KRT14 ratio might be indicative of a slight contamination of the T4 fraction with basal keratinocytes. Nevertheless, the large SCCE ratio indicates that very few, if any, GKs were present in the T1 fraction. From this, we concluded that the T4 fraction was highly enriched in GKs and thus suitable for a large-scale study of their transcriptome.

Table 1

Expression ratios for KRT14 and KLK7 as measured by real-time PCR from four independent samples

Sample no.

Expression ratio

KRT14 (T1/T4)

7.5

5.9

13.6

SCCE/KLK7 (T4/T1)

164

189

120

Figure 1

Histological analysis of epidermis samples

Histological analysis of epidermis samples. (a) Hematoxylin-eosin stained sections of entire epidermis after thermolysin incubation and removal of the dermis. (b,c,d) Epidermis fragments remaining after the first, second, and third trypsin incubation, respectively. Fragments shown in (d) are mainly composed of GKs attached to the cornified layer and constitute the T4 fraction. Inset: higher magnification showing the characteristic cytological aspect of a GK with cytoplasmic keratohyalin granules.

An ORESTES dataset from human granular keratinocytes

PolyA⁺RNA was extracted from the T4 fraction from individual 3 (Table 1) and used to generate cDNA mini-libraries using the ORESTES method 9. This sample was chosen as it presents the highest T1/T4 expression ratio for the KRT14 gene, suggesting a low contamination of the T4 fraction by basal keratinocytes. This method uses arbitrarily chosen primers for reverse transcription and PCR amplification. The successful amplification of a mRNA thus depends primarily on partial sequence homology with the primer, rather than on its abundance. This, and the elimination of cDNA preparations that display prominent bands on gels (indicative of the selective amplification of particular mRNAs), results in a normalization process and allows the detection of rare transcripts. We constructed 150 cDNA libraries with different primers, the analysis of 100-200 clones from each leading to the production of 22,585 sequences (Figure 2a). Among these, 1,453 (approximately 6%) corresponded to empty plasmids or uninformative sequences, 377 (1.7%) were of bacterial origin, and 2,303 (10%) matched the human mitochondrial genome. Despite two rounds of polyA⁺RNA purification, 1,859 sequences (8.2%) arose from ribosomal RNA. In addition, 187 sequences corresponded to unspliced intergenic DNA and may reflect spurious transcriptional activity. The remaining 16,591 sequences (73%) matched known or predicted transcribed regions, of which 62% aligned with the human genome in several blocks, and thus corresponded to spliced transcripts. After clustering, we observed the transcription of 3,387 genes by GKs. Additionally, 23 sequences matched overlapping exons belonging to two genes transcribed in opposite orientations and thus could not be attributed to a single gene.

Figure 2

Analysis of the ORESTES dataset from GKs

Analysis of the ORESTES dataset from GKs. (a) Pie graph of the 22,585 sequences obtained from the T4 fraction enriched in GKs. The treatment of the mRNA samples with DNAse resulted in minimal contamination with genomic sequences. Despite two rounds of polyA+ mRNA purification, rRNA sequences still represent approximately 8% of the dataset. (b) Histogram showing the number of ORESTES at each level of redundancy. The vast majority of genes are represented by less than five ORESTES, illustrating the normalization capability of that method. However, a small number of genes are represented by a large number of ORESTES (up to 402).

The normalization ability of the ORESTES method was examined by classifying genes according to the number of matching sequences in the dataset (Figure 2b). Half of the genes were represented by a unique sequence and 76.3% by three or less sequences, thus showing an acceptable level of normalization, with a mean of 4.6 ORESTES per gene. However, the ORESTES method only partially compensates for transcript abundance, as several genes were represented by a large ORESTES number. In these cases, we examined the number of sequences in the corresponding UniGene clusters, a rough measure of gene expression level. This revealed two situations: first, the gene is strongly expressed in many cell types including GKs (a high number of both ORESTES and UniGene entries); and second, the gene is particularly expressed in GKs (a high number of ORESTES, but low number of UniGene entries). The first category mainly includes housekeeping genes from the translation machinery (for example, RPS8, EEF1A1, RPL3, RPL7A, RPL28; Table 2). The second category contains genes previously described as implicated in epidermis barrier function (for example, KRT1, DMKN, LEP7, FLG, KRT2A, SPRR2E, CASP14, CDSN, hKRP, SBSN) and, interestingly, new candidates for this function (TSPAN5, DUOX2, TMEM14C, SERPINA12, SLC22A5, FLG2, C7orf24). Dermokine (DMKN), represented by 217 ORESTES, was shown to be selectively transcribed in mouse GKs by high-throughput in situ hybridization 15 and signal sequence trap 16 screens. The present ORESTES dataset allowed us to describe 13 novel human DMKN splicing isoforms with distinct subcellular locations and expression patterns 17.

Table 2

Representative sample of genes with the highest number of ORESTES

No. of ORESTES

Gene symbol

No. of UniGene ESTs

Full name (alias)

Ubiquitously expressed genes with a high number of UniGene ESTs

142

RPS8

3,382

Ribosomal protein S8

115

EEF1A1

29,374

Eukaryotic translation elongation factor 1 alpha 1

HLA-B

4,536

Major histocompatibility complex, class I, B

RPL3

11,561

Ribosomal protein L3

NCL

2,970

Nucleolin

RPL28

2,394

Ribosomal protein L28

RPL7A

5,864

Ribosomal protein l7a

RPSA

5,623

Ribosomal protein SA

PABPC1

4,385

Poly(A) binding protein, cytoplasmic 1

RPS18

2,292

Ribosomal protein S18

Known epidermis specific genes

402

KRT1

134

Keratin 1

217

DMKN

275

Dermokine

140

LEP7

Late envelope protein 7 (xp32)

100

FLG

Filaggrin

KRT2A

Keratin 2A

SPRR2E

Small proline-rich protein 2E

CASP14

Caspase 14

CDSN

Corneodesmosin

hKPRP

Human keratinocyte proline rich protein

PKP1

263

Plakophilin 1

SBSN

Suprabasin

DSG1

Desmoglein 1

Genes with unknown function

193

TSPAN5

526

Tetraspanin 5

127

DUOX2

Dual oxidase 2

TMEM14C

476

Transmembrane protein 14C

SERPINA12

Serpin peptidase inhibitor, clade A, member 12

SLC22A5

142

Solute carrier family 22, member 5

FLG2

Filaggrin 2 (ifapsoriasin)

C7orf24

309

Chromosome 7 open reading frame 24

The ORESTES dataset was aligned with the human genome using BLAT 18. The BLAT results were used to write a custom track that allows the visualization of the position of a particular ORESTE relative to other annotations such as RefSeq genes, vertebrate orthologues, single nucleotide polymorphisms, microarray expression data, and so on, and is freely available online 19. A screen copy of a UCSC Genome Browser window showing the ORESTES obtained for the C1orf81 gene is presented as an example (Additional data file 1). Indeed, this gene was characterized and a cDNA (DQ983818) was cloned for the first time in this study (see below). Our dataset includes the 16,591 ESTs matching known or predicted transcribed regions. These sequences have also been deposited in public databases (GenBank:EL593304-EL595248, GenBank:CU442764-CU457374).

Poorly represented genes in expressed sequence databases

As few sequencing projects from human epidermis have been performed so far (relative to other organs), genes expressed during the late steps of epidermis differentiation are poorly represented in sequence databases. Among the 3,375 genes from our set, 330 (10%) corresponded to UniGene clusters containing less than 100 mRNA/EST sequences, and were thus good candidates for epidermis late-expressed genes. These were subdivided into five classes. The first one contains all the genes (50) already known to be specifically expressed in the suprabasal layers (Table 3). This confirms that late-expressed genes are poorly represented in EST databases. The second class consisted of 31 genes with known or inferred functions that were previously known as mainly expressed in a specific tissue different from epidermis (Table 4). We suggest that some of them might play a specific role in epidermal differentiation. This could be the case for SERPINA12, DUOX2, and, to a lesser extent, CASZ1, which are represented by a large ORESTES number. We also suspect that CLDN23 might play an important role in GKs, since claudin-based tight junctions in the granular layer contribute to barrier function of the epidermis 20. Accordingly, claudin-1-deficient mice display a lethal defect in skin permeability 21. The third class gathered 32 uncharacterized paralogues of known genes (Table 5). The fourth class was composed of 105 genes that remain hypothetical and about which nothing is known regarding their normal function or disease relevance (Table 6). The fifth class contained genes that are expressed, most probably at low levels, in numerous tissues, but whose epidermal expression is, to the best of our knowledge, described here for the first time (Additional data file 2). Several genes from these five classes were selected to quantify their expression in the course of epidermal differentiation by real-time PCR (see below).

Table 3

Genes with less than 100 UniGene ESTs encoding known GK expressed proteins

No. of ORESTES

Gene symbol

No. of UniGene ESTs

Full name (alias)

LCE1F

Late cornified envelope 1F

LCE2C

Late cornified envelope 2C

C1orf46

Chromosome 1 open reading frame 46 (xp 33)

LCE2A

Late cornified envelope 2A

LCE5A

Late cornified envelope 5A

LCE1A

Late cornified envelope 1A

PGLYRP3

Peptidoglycan recognition protein 3

LCE1C

Late cornified envelope 1C

100

FLG

Filaggrin

140

LEP7

Late envelope protein 7

RPTN

Repetin

LCE2B

Late cornified envelope 2B

hKPRP

Human keratinocyte proline rich protein

LOR

Loricrin

KRT2A

Keratin 2A

C1orf42

Chromosome 1 open reading frame 42 (NICE-1)

TGM5

Transglutaminase 5

DSC1

Desmocollin 1

KRT1B

Keratin 1B

CASP14

Caspase 14

CNFN

Cornifelin

CALML5

Calmodulin-like 5

ALOXE3

Arachidonate lipoxygenase 3

ALOX12B

Arachidonate 12-lipoxygenase, 12R type

SPRR2E

Small proline-rich protein 2E

IVL

Involucrin

EPPK1

Epiplakin 1

POU2F3

POU domain, class 2, transcription factor 3 (oct-11)

ICHTHYIN

Ichthyin

SBSN

Suprabasin

KLK8

Kallikrein 8 (neuropsin/ovasin)

TGM3

Transglutaminase 3

ABCA12

ATP-binding cassette, sub-family A (ABC1), member 12

PADI1

Peptidylarginine deiminase, type I

DSG1

Desmoglein 1

GJB3

Gap junction protein, beta 3 (connexin 31)

CALML3

Calmodulin-like 3

SASpase

Skin aspartic protease

KLK7/SCCE

Kallikrein 7 (Stratum corneum chymotrypticenzyme)

A2ML1

Alpha-2-macroglobulin-like 1

CST6

Cystatin E/M

SULT2B1

Sulfotransferase family, cytosolic, 2B, member 1

KLK11

Kallikrein 11

HAL

Histidine ammonia-lyase (histidase)

EVPL

Envoplakin

CDSN

Corneodesmosin

PDZK1IP1

PDZK1 interacting protein 1

TGM1

Transglutaminase 1

SERPINB8

Serpin peptidase inhibitor, clade B, member 8

SCEL

Sciellin

Table 4

Genes with 100 or less UniGene ESTs, known as mainly expressed in a specific tissue different from epidermis

No. of ORESTES

Gene symbol

No. of UniGene ESTs

Full name

Main specificity

SERPINA12

Serpin peptidase inhibitor, clade A, member 12

Adipocytes

BSND

Bartter syndrome, infantile, with sensorineural deafness

Kidney and inner ear

OPN1LW

Opsin 1, long-wave-sensitive

Eye

GRIN2

G-protein-regulated inducer of neurite outgrowth

Brain

IL1RL2

Interleukin 1 receptor-like 2

Neurons

LCTL

Lactase-like

Kidney

PPEF2

Protein phosphatase, EF-hand calcium binding domain 2

Retina

SLC6A3

Solute carrier family 6, member 3

Neuron

CDC42BPG

CDC42 binding protein kinase gamma

Heart and skeletal muscle

GPR75

G protein-coupled receptor 75

Retina

OTX1

Orthodenticle homolog 1

Neurons

K5B

Keratin 5b

Tongue

TBX15

T-box 15

Embryo

TMPRSS5

Transmembrane protease, serine 5 (spinesin)

Spinal chord

LEAP-2

Liver-expressed antimicrobial peptide 2

Liver

BMP8B

Bone morphogenetic protein 8B

Embryo

PTGFR

Prostaglandin F receptor

Uterus

TEC

Tec protein tyrosine kinase

Hematopoietic cells

SLC5A1

Solute carrier family 5, member 1

Intestine and kidney

CASZ1

Castor homolog 1, zinc finger

Mesenchyme

KCNJ12

Potassium inwardly rectifying channel, subfamily J, 12

Heart

P11

26 serine protease

Placenta

SERPINB7

Serpin peptidase inhibitor, clade B, member 7

Mesangial cells

127

DUOX2

Dual oxidase 2

Thyroid

GDPD2

Glycerophosphodiester phosphodiesterase containing 2

Osteoblasts

PDE11A

Phosphodiesterase 11A

Testis

CLDN23

Claudin 23

Placenta

PLCL4

Phospholipase C-like 4

Neurons

EYA4

Eyes absent homolog 4

Heart and cochlea

LIPH

Lipase, member H

Intestine

RBP3

Retinol binding protein 3

Retina

Table 5

Genes with 100 or less UniGene ESTs, corresponding to uncharacterized paralogues of known genes

No. of ORESTES

Gene symbol

No. of UniGene ESTs

Full name

ASAH3

N-acylsphingosine amidohydrolase 3

LIPL2 (LIPK)

Lipase-like, ab-hydrolase domain containing 2

CLEC2A

C-type lectin domain family 2, member A

IGFL3

Insulin growth factor-like family member 3

LYG2

Lysozyme-like

PNPLA1

Patatin-like phospholipase domain containing 1

GSDM1

Gasdermin 1

GRID2IP

Glutamate receptor, ionotropic, delta 2 interacting protein

IL1F7

Interleukin 1 family, member 7

FCRL6

Fc receptor-like 6

AADACL2

Arylacetamide deacetylase-like 2

LIPL3 (LIPM)

Lipase-like, ab-hydrolase domain containing 3

LAMB4

Laminin, beta 4

THEM5

Thioesterase superfamily member 5

FLJ90165

Gamma-glutamyltransferase 6 homolog

FLJ45651

Phospholipase A2, group IVE

LPIN3

Lipin 3

SLC25A34

Solute carrier family 25, member 34

GPR115

G protein-coupled receptor 115

LRP5L

Low density lipoprotein receptor-related protein 5-like

HSPC105

NAD(P) dependent steroid dehydrogenase-like

QPCTL

Glutaminyl-peptide cyclotransferase-like

PLA2G4F

Phospholipase A2, group IVF

KIAA0605

ADAMTS-like 2

CTGLF1

Centaurin, gamma-like family, member 1

UGT3A2

UDP glycosyltransferase 3 family, polypeptide A2

GALNT17

Polypeptide N-acetylgalactosaminyltransferase 17

BAIAP2L2

BAI1-associated protein 2-like 2

FLJ43692

ARHGEF5-like

VILL

Villin-like

LOC203427

Similar to solute carrier family 25, member 16

IL17RE

100

Interleukin 17 receptor E

Table 6

Unknown genes with 100 or less UniGene ESTs

No. of ORESTES

Gene symbol

No. of UniGene ESTs

Full name

FLJ43861

Flj43861

LOC389791

Hypothetical gene supported by AK094537

LOC285435

Hypothetical LOC285435

LOC387846

Hypothetical LOC387846

LOC401062

Hypothetical gene supported by AK092973

IMAGE:5260914

Image:5260914

LOC338667

Hypothetical protein LOC338667

PSORS1C2

Psoriasis susceptibility 1 candidate 2

DKFZp779B1540

Hypothetical protein dkfzp779b1540

C14orf72

Chromosome 14 open reading frame 72

FLJ37989

Flj37989

FLG2

Filaggrin 2 (ifapsoriasin)

WFDC5

WAP four-disulfide core domain 5

LOC402110

Hypothetical LOC402110

PLEKHN1

Pleckstrin homology domain containing, family N member 1

LOC441240

Hypothetical protein LOC441240

FLJ38159

Hypothetical protein FLJ38159

C1orf177

Chromosome 1 open reading frame 177

HMCN2

Hemicentin 2

MGC23985

Similar to AVLV472

OFCC1

Orofacial cleft 1 candidate 1

LOC441860

Novel KRAB box containing C2H2 type zinc finger protein

AMIGO3

Adhesion molecule with Ig-like domain 3

LOC441257

Hypothetical protein LOC441257

LOC285484

Hypothetical protein LOC285484

C20orf91

Chromosome 20 open reading frame 91

LOC202460

Hypothetical protein LOC202460

FLJ25664

Flj25664

FLJ41623

Flj41623

LOC342897