Alpha-helical Coiled-coil Rod Research Articles

Cell cycle regulation of the psoriasis associated gene CCHCR1 by transcription factor E2F1.

The coiled-coil alpha-helical rod protein 1 (CCHCR1) was first identified as a candidate gene in psoriasis and has lately been found to be associated with a wide range of clinical conditions including COVID-19. CCHCR1 is located within P-bodies and centrosomes, but its exact role in these two subcellular structures and its transcriptional control remain largely unknown. Here, we showed that CCHCR1 shares a bidirectional promoter with its neighboring gene, TCF19. This bidirectional promoter is activated by the G1/S-regulatory transcription factor E2F1, and both genes are co-induced during the G1/S transition of the cell cycle. A luciferase reporter assay suggests that the short intergenic sequence, only 287 bp in length, is sufficient for the G1/S induction of both genes, but the expression of CCHCR1 is further enhanced by the presence of exon 1 from both TCF19 and CCHCR1. This research uncovers the transcriptional regulation of the CCHCR1 gene, offering new perspectives on its function. These findings contribute to the broader understanding of diseases associated with CCHCR1 and may serve as a foundational benchmark for future research in these vital medical fields.

The Potentials of Herbal Plant against the Psoriasis

Chronic autoimmune skin disease termed psoriasis is characterised by excessive keratinocyte multiplication, scaly plaques, severe inflammation, and erythema. T lymphocytes, leukocytes, vascular endothelium, and epidermal keratinocytes also contribute in the pathogenesis of psoriasis. Increased leukocyte recruitment and increased levels of cytokines, growth factors, and genetic factors like interleukin (IL)-1, IL-6, IL-17, IL-22, IL-23, tumour necrosis factor (TNF), interferon (IFN), transforming growth factor (TGF), toll-like receptor (TLR)-2, signal transducer and activator of transcription (STAT-3), 15-lipoxygenase (LOX)-2. The most important aspects impacting the treatment of psoriasis are coiled-coil alpha-helical rod protein 1 (CCHCR1), steroidogenic acute regulatory protein (StAR), and vitamin D receptor (VDR). Various synthetic medicinal drugs have also been known to have the side effect of psoriasis. Due to their safety and accessibility, herbal medications may indicate the potential as effective anti-psoriatic agents.
 Keywords: Psoriasis, Herbal Drug, Silybum marianum, Thespesia populnea, Mahonia aquifolium

Clinical Findings, Response to Steroid Treatment, and Recurrence Rate in Alopecia Areata Patients with or without a Nonsynonymous Variant of Coiled-Coil Alpha-Helical Rod Protein 1.

Alopecia areata (AA) is considered complex genetic and tissue-specific autoimmune disease. We recently discovered a nonsynonymous variant in the coiled-coil alpha-helical rod protein 1 (CCHCR1) gene within the AA risk haplotype. And a water avoidance stress test on CCHCR1 knockout mice induced AA-like lesions. To investigate the difference clinical findings of AA in patients with the CCHCR1 variant and without. We conducted a retrospective analysis of the data from 142 AA patients. Among these patients, 20 (14.1%) had a variant of CCHCR1. We evaluated the sex distribution of the patients, age at onset, distribution of the clinical types, prevalence of a positive family history of AA, prevalence of association of AA with atopic dermatitis, response to steroid therapy, and recurrence rate. We used multivariate logistic regression analysis and Fisher's exact test for statistical analysis. We also investigate electron microscopic observations of hair samples with the CCHCR1 variant and without. The results showed a significant correlation between the CCHCR1 variant and the recurrence rate compared with the variant-negative group (p=0.0072). Electron microscopy revealed abnormalities in the hair shaft structure and hair cuticle in patients with the CCHCR1 variant (p=0.00174). Our results suggest that AA with CCHCR1 variant is clinically characterized by a high recurrence rate and hair morphological abnormality.

CCHCR1-astrin interaction promotes centriole duplication through recruitment of CEP72

BackgroundThe centrosome is one of the most important non-membranous organelles regulating microtubule organization and progression of cell mitosis. The coiled-coil alpha-helical rod protein 1 (CCHCR1, also known as HCR) gene is considered to be a psoriasis susceptibility gene, and the protein is suggested to be localized to the P-bodies and centrosomes in mammalian cells. However, the exact cellular function of HCR and its potential regulatory role in the centrosomes remain unexplored.ResultsWe found that HCR interacts directly with astrin, a key factor in centrosome maturation and mitosis. Immunoprecipitation assays showed that the coiled-coil region present in the C-terminus of HCR and astrin respectively mediated the interaction between them. Astrin not only recruits HCR to the centrosome, but also protects HCR from ubiquitin-proteasome-mediated degradation. In addition, depletion of either HCR or astrin significantly reduced centrosome localization of CEP72 and subsequent MCPH proteins, including CEP152, CDK5RAP2, and CEP63. The absence of HCR also caused centriole duplication defects and mitotic errors, resulting in multipolar spindle formation, genomic instability, and DNA damage.ConclusionWe conclude that HCR is localized and stabilized at the centrosome by directly binding to astrin. HCR are required for the centrosomal recruitment of MCPH proteins and centriolar duplication. Both HCR and astrin play key roles in keeping normal microtubule assembly and maintaining genomic stability.

The Alopecia Areata Phenotype Is Induced by the Water Avoidance Stress Test In cchcr1-Deficient Mice

We recently discovered a nonsynonymous variant in the coiled-coil alpha-helical rod protein 1 (CCHCR1) gene within the alopecia areata (AA) risk haplotype. We also reported that the engineered mice with this risk allele exhibited. To investigate more about the involvement of the CCHCR1 gene in AA pathogenesis, we developed an AA model using C57BL/6N cchcr1 gene knockout mice. In this study, mice (6–8 weeks) were divided into two groups: cchcr1−/− mice and wild-type (WT) littermates. Both groups were subjected to a water avoidance stress (WAS) test. Eight weeks after the WAS test, 25% of cchcr1−/− mice exhibited non-inflammatory foci of alopecia on the dorsal skin. On the other hand, none of wild-type littermates cause hair loss. The foci resembled human AA in terms of gross morphology, trichoscopic findings and histological findings. Additionally, gene expression microarray analysis of cchcr1−/− mice revealed abnormalities of hair related genes compared to the control. Our results strongly suggest that CCHCR1 is associated with AA pathogenesis and that cchcr1−/− mice are a good model for investigating AA.

Identification of protein/mRNA network involving the PSORS1 locus gene CCHCR1 and the PSORS4 locus gene HAX1

CCHCR1 (Coiled-Coil alpha-Helical Rod 1), maps to chromosomal region 6p21.3, within the major psoriasis susceptibility locus PSORS1. CCHCR1 itself is a plausible psoriasis candidate gene, however its role in psoriasis pathogenesis remains unclear. We previously demonstrated that CCHCR1 protein acts as a cytoplasmic docking site for RNA polymerase II core subunit 3 (RPB3) in cycling cells, suggesting a role for CCHCR1 in vesicular trafficking between cellular compartments.Here, we report a novel interaction between CCHCR1 and the RNA binding protein HAX1. HAX1 maps to chromosomal region 1q21.3 within the PSORS4 locus and is over-expressed in psoriasis. Both CCHCR1 and HAX1 share subcellular co-localization with mitochondria, nuclei and cytoplasmic vesicles as P-bodies. By a series of ribonucleoprotein immunoprecipitation (RIP) assays, we isolated a pool of mRNAs complexed with HAX1 and/or CCHCR1 proteins. Among the mRNAs complexed with both CCHCR1 and HAX1 proteins, there are Vimentin mRNA, previously described to be bound by HAX1, and CAMP/LL37 mRNA, whose gene product is over-expressed in psoriasis.

Alopecia areata susceptibility variant in MHC region impacts expressions of genes contributing to hair keratinization and is involved in hair loss.

BackgroundAlopecia areata (AA) is considered a highly heritable, T-cell-mediated autoimmune disease of the hair follicle. However, no convincing susceptibility gene has yet been pinpointed in the major histocompatibility complex (MHC), a genome region known to be associated with AA as compared to other regions.MethodsWe engineered mice carrying AA risk allele identified by haplotype sequencing for the MHC region using allele-specific genome editing with the CRISPR/Cas9 system. Finally, we performed functional evaluations in the mice and AA patients with and without the risk allele.FindingsWe identified a variant (rs142986308, p.Arg587Trp) in the coiled-coil alpha-helical rod protein 1 (CCHCR1) gene as the only non-synonymous variant in the AA risk haplotype. Furthermore, mice engineered to carry the risk allele displayed a hair loss phenotype. Transcriptomics further identified CCHCR1 as a novel component interacting with hair cortex keratin in hair shafts. Both, these alopecic mice and AA patients with the risk allele displayed morphologically impaired hair and comparable differential expression of hair-related genes, including hair keratin and keratin-associated proteins (KRTAPs).InterpretationOur results implicate CCHCR1 with the risk allele in a previously unidentified subtype of AA based on aberrant keratinization in addition to autoimmune events.FundingThis work was supported by JSPS KAKENHI (JP16K10177) and the NIHR UCLH Biomedical Research center (BRC84/CN/SB/5984).

Phylogenetic profiling and gene expression studies implicate a primary role of PSORS1C2 in terminal differentiation of keratinocytes.

PSORS1C2 is a gene located between coiled-coil alpha-helical rod protein 1 (CCHCR1) and corneodesmosin (CDSN) within the psoriasis susceptibility locus 1 (PSORS1). Here, we performed a comparative genomics analysis of the as-yet incompletely characterized PSORS1C2 gene and determined its expression pattern in human tissues. In contrast to CCHCR1, which is common to all vertebrates investigated, PSORS1C2 and CDSN are present exclusively in mammals, indicating that the latter genes have originated after the evolutionary divergence of mammals and reptiles. CDSN is conserved in aquatic mammals, whereas PSORS1C2 orthologs contain gene-inactivating frame shift mutations in whales and dolphins, in which the epidermal differentiation programme has degenerated. Reverse-transcription PCR screening demonstrated that, in human tissues, PSORS1C2 is expressed principally in the epidermis and weakly in the thymus. PSORS1C2 mRNA was strongly upregulated during terminal differentiation of human keratinocytes in vitro. Immunohistochemistry revealed exclusive expression of PSORS1C2 in the granular layer of the epidermis and in cornifying epithelial cells of Hassall's corpuscles of the thymus. In summary, our results identify PSORS1C2 as a keratinocyte cornification-associated protein that has originated in evolutionarily basal mammals and has undergone gene inactivation in association with the loss of the skin barrier function in aquatic mammals.

Inhibition of imiquimod-induced psoriasis-like dermatitis in mice by herbal extracts from some Indian medicinal plants.

Psoriasis is a chronic autoimmune human skin disorder that is characterized by excessive proliferation of keratinocytes, scaly plaques, severe inflammation and erythema. The pathophysiology of psoriasis involves interplay between epidermal keratinocytes, T lymphocytes, leukocytes and vascular endothelium. Increased leukocyte recruitment and elevated levels of cytokines, growth factors and genetic factors like interleukin (IL)-1β, IL-6, IL-17, IL-22, IL-23, tumour necrosis factor (TNF)-α, interferon (IFN)-γ, transforming growth factor (TGF)-β, toll-like receptor (TLR)-2, signal transducer and activator of transcription (STAT-3), 15-lipoxygenase (LOX)-2, coiled-coil alpha-helical rod protein 1 (CCHCR1), steroidogenic acute regulatory protein (StAR) and vitamin D receptor (VDR) are the most critical factors governing the exacerbation of psoriasis. In the present study, an attempt was made to elucidate the preventive role of herbal extracts of four dermo-protective Ayurvedic plants, Tinospora cordifolia (TC), Curcuma longa (CL), Celastrus paniculatus (CP) and Aloe vera (AV), against psoriasis-like dermatitis. Parkes (P) strain mice were initially induced with psoriasis-like dermatitis using topical application of imiquimod (IMQ, 5 %), followed by subsequent treatment with the herbal extracts to examine their curative effect on the psoriasis-like dermatitis-induced mice. The extracts were orally/topically administered to mice according to their ED/LD50 doses. Phenotypical observations, histological examinations, and semi-quantitative reverse transcription PCR (RT-PCR) analyses of the skin and blood samples of the control, IMQ-treated and herbal extract-treated psoriasis-like dermatitis-induced mice lead to the conclusion that the combination extract from all the plants was instrumental in downregulating the overexpressed cytokines, which was followed by the CL extract. Moreover, lesser yet positive response was evident from CP and TC extracts. The results suggest that these plants can prove to have tremendous preventive potential against the disease and can open the way to new therapeutic strategies for psoriasis treatment.

Susceptibility Genes for Multiple Sclerosis Identified in a Gene-Based Genome-Wide Association Study.

Background and PurposeMultiple sclerosis (MS) is a demyelinating and inflammatory disease of the central nervous system. The aim of this study was to identify more genes associated with MS.MethodsBased on the publicly available data of the single-nucleotide polymorphism-based genome-wide association study (GWAS) from the database of Genotypes and Phenotypes, we conducted a powerful gene-based GWAS in an initial sample with 931 family trios, and a replication study sample with 978 cases and 883 controls. For interesting genes, gene expression in MS-related cells between MS cases and controls was examined by using publicly available datasets.ResultsA total of 58 genes was identified, including 20 "novel" genes significantly associated with MS (p<1.40×10-4). In the replication study, 44 of the 58 identified genes had been genotyped and 35 replicated the association. In the gene-expression study, 21 of the 58 identified genes exhibited differential expressions in MS-related cells. Thus, 15 novel genes were supported by replicated association and/or differential expression. In particular, four of the novel genes, those encoding myelin oligodendrocyte glycoprotein (MOG), coiled-coil alpha-helical rod protein 1 (CCHCR1), human leukocyte antigen complex group 22 (HCG22), and major histocompatibility complex, class II, DM alpha (HLA-DMA), were supported by the evidence of both.ConclusionsThe results of this study emphasize the high power of gene-based GWAS in detecting the susceptibility genes of MS. The novel genes identified herein may provide new insights into the molecular genetic mechanisms underlying MS.

Psoriasis-Associated Genetic Polymorphism in North Indian Population in the CCHCR1 Gene and in a Genomic Segment Flanking the HLA-C Region

Psoriasis is a common, chronic, recurrent, inflammatory, hyper proliferative disorder of the skin, which has a relatively high prevalence in the general population (0.6–4.8%). Linkage and association analyses in various populations have revealed a major locus for psoriasis susceptibility, PSORS1, at 6p21.3. Association of the disease with human leukocyte antigen (HLA) Cw6, corneodesmosin (CDSN) and the coiled-coil alpha-helical rod protein-1 (CCHCR1) has also been reported. Though the PSORS1 locus accounts for 30–50% of familial psoriasis in various global population groups, yet no studies have been published from the North Indian population. Some of the SNPs in HLA-C and CCHCR1 genes have been reported as markers for disease susceptibility. Therefore in the present study, DNA samples from psoriasis patients from North India were genotyped for polymorphisms in CCHCR1 and HLA-C genes. The allele frequencies were calculated for patients and controls, and were compared for odds ratio and confidence interval values. SNPn.7*22222 (rs12208888), SNPn.7*22333 (rs12216025), SNPn.9*24118 (rs10456057), CCHCR1_386 (rs130065), CCHCR1_404 (rs130076) and CCHCR1_1364 (rs130071) were found to be significant in psoriasis patients. Linkage disequilibrium analysis revealed two haplotypes (rs12208888,rs2844608,rs12216025,rs10456057,rs130065,rs130066,rs130068,rs130269,andrs12208888,rs2844608,rs12216025,rs130076,rs130066,rs130068,rs130269,rs130071) as highly susceptible haplotypes for psoriasis in the cohort studied. Preliminary analysis of the data also suggests the possibilities of ethnic group specific disease related polymorphisms, pending validation in future studies.

Psoriasis-associated genetic polymorphism in North Indian population in the CCHCR1 gene and in a genomic segment flanking the HLA-C region.

Psoriasis is a common, chronic, recurrent, inflammatory, hyper proliferative disorder of the skin, which has a relatively high prevalence in the general population (0.6–4.8%). Linkage and association analyses in various populations have revealed a major locus for psoriasis susceptibility, PSORS1, at 6p21.3. Association of the disease with human leukocyte antigen (HLA) Cw6, corneodesmosin (CDSN) and the coiled-coil alpha-helical rod protein-1 (CCHCR1) has also been reported. Though the PSORS1 locus accounts for 30–50% of familial psoriasis in various global population groups, yet no studies have been published from the North Indian population. Some of the SNPs in HLA-C and CCHCR1 genes have been reported as markers for disease susceptibility. Therefore in the present study, DNA samples from psoriasis patients from North India were genotyped for polymorphisms in CCHCR1 and HLA-C genes. The allele frequencies were calculated for patients and controls, and were compared for odds ratio and confidence interval values. SNPn.7*22222 (rs12208888), SNPn.7*22333 (rs12216025), SNPn.9*24118 (rs10456057), CCHCR1_386 (rs130065), CCHCR1_404 (rs130076) and CCHCR1_1364 (rs130071) were found to be significant in psoriasis patients. Linkage disequilibrium analysis revealed two haplotypes (rs12208888, rs2844608, rs12216025, rs10456057, rs130065, rs130066, rs130068, rs130269, and rs12208888, rs2844608, rs12216025, rs130076, rs130066, rs130068, rs130269, rs130071) as highly susceptible haplotypes for psoriasis in the cohort studied. Preliminary analysis of the data also suggests the possibilities of ethnic group specific disease related polymorphisms, pending validation in future studies.

Common Structural Motifs for the Regulation of Divergent Class II Myosins

This minireview focuses on structural studies that have provided insights into our current understanding of thick filament regulation in muscle. We describe how different domains in the myosin molecule interact to produce an inactive "off" state; included are head-head and head-rod interactions, the role of the regulatory light chain, and the significance of the alpha-helical coiled-coil rod in regulation. Several of these interactions have now been visualized in a wide variety of native myosin filaments, testifying to the generality of these structural motifs across the phylogenetic tree.

Atomic structure of vimentin coil 2

Intermediate filaments (IFs) are essential cytoskeletal components in metazoan cells. They assemble from elementary dimers that are built around the central alpha-helical coiled-coil rod domain representing the IF 'signature'. The rod consists of two similarly-sized parts, coil 1 and coil 2, connected by a non-alpha-helical linker L12. Coil 2 is absolutely conserved in length across all IF types and was initially predicted to consist of a short coiled-coil segment 2A based on a heptad pattern of hydrophobic residues, another linker L2 and a coiled-coil segment 2B. Here we present the crystal structure of human vimentin fragment including residues 261-335 i.e. approximately the first half of coil 2. The N-terminal part of this fragment reveals a parallel alpha-helical bundle characterized by 3.5 consecutive hendecad repeats. It is immediately followed by a regular left-handed coiled coil. The distinct non-helical linker L2 is therefore not observed. Together with the previously determined crystal structure of the major part of segment 2B (Strelkov et al., 2002), we can now build a complete atomic model of the 21nm long vimentin coil 2 dimer being a relatively rigid rod.

Propensity for DNA Damage in Psoriasis Patients Genotyped for Two Candidate Genes

Studies assessing genetic damage and its association with disease-candidate genes in patients belonging to geographically distinct populations are scanty. The present study evaluated DNA damage using the alkaline Single Cell Gel Electrophoresis assay in peripheral blood leukocytes of Psoriasis Punjabi Patients on systemic-topical therapy who had been genotyped for two disease-candidate genes (HLA-C, human leukocyte antigen and the coiled-coil alpha-helical rod protein 1(CCHCR1). Genetic damage was disease gene-influenced as homozygous mutants for CCHCR1 Exon 4 site 386* (C→T) and heterozygous mutants for 404* (C→T) alleles had significantly more damage (p<0.05) compared to respective homozygous wild types. The arginine to tryptophan substitution alters the protein, triggering keratinocyte proliferation and probably inflammation/ oxidative stress. This along with drug-treatment probably caused the observed DNA damage. Population sub-groups had no within group differences but larger sizes can explore this possibility. Studies of this type can provide disease-gene-damage prone information for exploring DNA- safe therapeutics.

CCHCR1 Is Up-Regulated in Skin Cancer and Associated with EGFR Expression

Despite chronic inflammation, psoriatic lesions hardly ever progress to skin cancer. Aberrant function of the CCHCR1 gene (Coiled-Coil α-Helical Rod protein 1, HCR) within the PSORS1 locus may contribute to the onset of psoriasis. As CCHCR1 is expressed in certain cancers and regulates keratinocyte (KC) proliferation in a transgenic mouse model, we studied its relation to proliferation in cutaneous squamous cell cancer (SCC) cell lines by expression arrays and quantitative RT-PCR and in skin tumors by immunohistochemistry. CCHCR1 protein was detected in the pushing border of SCC and lining basal cell carcinoma islands. Different from psoriasis, Ki67 had a similar expression pattern as CCHCR1. The most intense CCHCR1 staining occurred in areas positive for epidermal growth factor receptor (EGFR). Expression of CCHCR1 mRNA was upregulated 30–80% in SCC lines when compared to normal KCs and correlated positively with Ki67 expression. The most aggressive and invasive tumor cell lines (RT3, FaDu) expressed CCHCR1 mRNA less than non-tumorigenic HaCaT cells. Moreover, the tumor promoters okadaic acid and menadione downregulated CCHCR1 mRNA. We conclude that both in psoriasis and the early stages of KC transformation, CCHCR1 may function as a negative regulator of proliferation, but beyond a certain point in oncogenesis cannot control this phenomenon any longer.

The PSORS1 locus gene CCHCR1 affects keratinocyte proliferation in transgenic mice

The CCHCR1 gene (Coiled-Coil alpha-Helical Rod protein 1) within the major psoriasis susceptibility locus PSORS1 is a plausible candidate gene for the risk effect. We have previously generated transgenic mice overexpressing either the psoriasis-associated risk allele CCHCR1*WWCC or the normal allele of CCHCR1. All transgenic CCHCR1 mice appeared phenotypically normal, but exhibited altered expression of genes relevant to the pathogenesis of psoriasis, including upregulation of hyperproliferation markers keratins 6, 16 and 17. Here, we challenged the skin of CCHCR1 transgenic mice with wounding or 12-O-tetradecanoyl-13-acetate (TPA), treatments able to induce epidermal hyperplasia and proliferation that both are hallmarks of psoriasis. These experiments revealed that CCHCR1 regulates keratinocyte proliferation. Early wound healing on days 1 and 4 was delayed, and TPA-induced epidermal hyperproliferation was less pronounced in mice with the CCHCR1*WWCC risk allele than in mice with the normal allele or in wild-type animals. Finally, we demonstrated that overexpression of CCHCR1 affects basal keratinocyte proliferation in mice; CCHCR1*WWCC mice had less proliferating keratinocytes than the non-risk allele mice. Similarly, keratinocytes isolated from risk allele mice proliferated more slowly in culture than wild-type cells when measured by BrdU labeling and ELISA. Our data show that CCHCR1 may function as a negative regulator of keratinocyte proliferation. Thus, aberrant function of CCHCR1 may lead to abnormal keratinocyte proliferation which is a key feature of psoriatic epidermis.

The CCHCR1 (HCR) gene is relevant for skin steroidogenesis and downregulated in cultured psoriatic keratinocytes

The HCR gene, officially called Coiled-Coil alpha-Helical Rod protein 1 (CCHCR1), located within the major psoriasis susceptibility locus PSORS1, is a plausible candidate gene for the risk effect. Recently, CCHCR1 was shown to promote steroidogenesis by interacting with the steroidogenic acute regulator protein (StAR). Here, we examined the role of CCHCR1 in psoriasis and cutaneous steroid metabolism. We found that CCHCR1 and StAR are expressed in basal keratinocytes in overlapping areas of the human skin, and CCHCR1 stimulated pregnenolone production in steroidogenesis assay. Overexpression of either the CCHCR1*WWCC risk allele or the non-risk allele enhanced steroid synthesis in vitro. Furthermore, the cytochrome P450scc enzyme was expressed in human keratinocytes and was induced by forskolin, a known activator of steroidogenesis, and forskolin also upregulated CCHCR1. CCHCR1 has an altered expression pattern in lesional psoriatic skin compared to normal healthy skin, suggesting its dysregulation in psoriasis. We found that the expression of CCHCR1 is downregulated twofold at the mRNA level in cultured non-lesional psoriatic keratinocytes when compared to non-psoriatic healthy cells. Our results also suggest a connection between CCHCR1 and vitamin D metabolism in keratinocytes. The expression of the vitamin D receptor (VDR) gene was lower in non-lesional psoriatic keratinocytes than in healthy cells. Furthermore, Vdr expression was downregulated in the keratinocytes of mice overexpressing the CCHCR1*WWCC risk allele when compared to keratinocytes from mice with the non-risk allele of CCHCR1. Finally, we demonstrate that other agents relevant for psoriasis and/or the regulation of steroidogenesis influence CCHCR1 expression in keratinocytes, including insulin, EGF, cholesterol, estrogen, and cyclosporin A. Taken the role of steroid hormones, including vitamin D and estrogen, in cell proliferation, epidermal barrier homeostasis, differentiation, and immune response, our results suggest a role for CCHCR1 in the pathogenesis of psoriasis via the regulation of skin steroid metabolism.

Visualization of an unstable coiled coil from the scallop myosin rod.

Alpha-helical coiled coils in muscle exemplify simplicity and economy of protein design: small variations in sequence lead to remarkable diversity in cellular functions. Myosin II is the key protein in muscle contraction, and the molecule's two-chain alpha-helical coiled-coil rod region--towards the carboxy terminus of the heavy chain--has unusual structural and dynamic features. The amino-terminal subfragment-2 (S2) domains of the rods can swing out from the thick filament backbone at a hinge in the coiled coil, allowing the two myosin 'heads' and their motor domains to interact with actin and generate tension. Most of the S2 rod appears to be a flexible coiled coil, but studies suggest that the structure at the N-terminal region is unstable, and unwinding or bending of the alpha-helices near the head-rod junction seems necessary for many of myosin's functional properties. Here we show the physical basis of a particularly weak coiled-coil segment by determining the 2.5-A-resolution crystal structure of a leucine-zipper-stabilized fragment of the scallop striated-muscle myosin rod adjacent to the head-rod junction. The N-terminal 14 residues are poorly ordered; the rest of the S2 segment forms a flexible coiled coil with poorly packed core residues. The unusual absence of interhelical salt bridges here exposes apolar core atoms to solvent.

Identification of multiple forms of 180-kDa ribosome receptor in human cells.

Herein, we describe the analysis and mapping of cDNA clones encoding variant forms of the human homolog of the canine 180-kDa ribosome receptor (p180). One form, similar to the chicken ES/130 homolog, possesses a large uninterrupted C-terminal region composed predominantly of heptad repeats predicted to form an alpha-helical double-stranded coiled-coil rod. Other forms contain in addition a 10-amino acid consensus motif, NQGKKAEGAQ, repeated up to 54 times in tandem close to the N-terminus. Such repeats in canine p180 represent a ribosome-binding domain. The cDNA hybridized to a major 6-kb transcript in all tissues examined, where very high expression was observed in tissues that carry out a high level of secretion such as pancreas, liver, and placenta. The ES130/p180 gene was mapped to chromosome 20p12, and a potential pseudogene appears to reside on chromosome 7. In summary, the data suggest that p180 exists in humans in different forms because of complete removal of tandem repeats, or partial intraexonic splicing, creating different repeat lengths with potentially novel ribosome-binding characteristics.