CTHRC1 overexpression promotes ectopic endometrial stromal cell proliferation, migration and invasion via activation of the Wnt/ß-catenin pathway.

RESEARCH QUESTION: Endometriosis is characterized by the occurrence of endometrial-like tissue outside the uterus. Collagen triple helix repeat containing-1 (CTHRC1) is known as a tumour-promoting factor in several neoplasms. This study aimed to examine the roles of CTHRC1 in the development and progression of endometriosis, and to unravel the underlying mechanisms. DESIGN: Quantitative real-time PCR, western blot analyses and enzyme-linked immunosorbent assay were performed to determine the expression levels of CTHRC1 in tissues and serum. In addition, CTHRC1 expression levels were knocked down by small-interfering RNA in ectopic endometrial stromal cells (EESC). Cell Counting Kit-8, fluorescence-activated cell sorting, Transwell and wound scratch assays were carried out to assess the underlying biological behaviours, and western blot analyses were performed to reveal the molecular mechanisms. RESULTS: mRNA and protein expression levels of CTHRC1 were markedly higher in ectopic endometrial tissues than in eutopic and control endometrial tissues. In addition, the serum concentration of CTHRC1 was apparently higher in the endometriosis group than the control group. Small interfering RNA knockdown of CTHRC1 suppressed the proliferation, migration, invasion and healing abilities of EESC. Furthermore, the protein expressions of key molecules in the Wnt/ß-catenin pathway showed an obvious down-regulated expression after siRNA transfection. CONCLUSIONS: These findings suggest that CTHRC1 may be partly responsible for the development and progression of endometriosis by increasing EESC proliferation, migration and invasion via the Wnt/ß-catenin pathway. CTHRC1 may thus serve as a diagnostic and therapeutic target for endometriosis.

Roles of cell migration and invasion mediated by Twist in endometriosis.

AIM: To investigate the roles of cell migration and invasion mediated by Twist in endometriosis. METHODS: The protein levels and locations of Twist, N-cadherin and E-cadherin were measured by Western blot and immunohistochemistry in ectopic endometrium and eutopic endometrium of ovarian endometriosis as well as normal endometrium of nonendometriosis patients. The messenger RNA (mRNA) expressions of Twist, N-cadherin and E-cadherin in these tissues were measured by quantitative reverse transcription polymerase chain reaction. Stable overexpression of Twist in eutopic endometrial stromal cells was transfected with a plasmid-mediated delivery system. The protein and mRNA expressions of N-cadherin and E-cadherin were detected by western blot and reverse transcription polymerase chain reaction. The changes of migration and invasion of endometrial stromal cells were explored by transwell. RESULTS: Levels of protein and mRNA of Twist and N-cadherin showed the highest expression in ectopic endometrium of ovarian endometriosis, while lowest in normal endometrium of nonendometriosis patients. On the contrary, the expression of E-cadherin showed highest in normal endometrium of nonendometriosis patients. The overexpression of Twist after transfection significantly upregulated the protein and mRNA expression of N-cadherin, while downregulated the protein and mRNA expression of E-cadherin. There is significant difference between groups. For transwell, the overexpression of Twist in eutopic endometrial stromal cell significantly promoted cell migration and invasion. CONCLUSION: Twist might be related with the increase of migration and invasion in endometrial stromal cells, mediated by epithelial-to-mesenchymal transition.

Correlation of polypeptide N-acetylgalactosamine transferases-3 and -6 to different stages of endometriosis.

PURPOSE: To investigate the expression patterns of N-acetyl galactosamine transferases (GalNAc-Ts)-3 and GalNAc-T6 in clinicopathologically characterized endometriosis (EMS), and to explore their clinical significance. METHODS: Ectopic and eutopic endometrial tissue samples were obtained and confirmed with CD-10 immunohistochemistry in patients with EMS (n = 12), whereas normal control endometrium was obtained from patients with uterine septum (n = 12). The mRNA and protein levels of GalNAc-T3 and GalNAc-T6 were detected in these samples using quantitative real-time PCR, immunohistochemistry, and western blotting. RESULTS: GalNAc-T3 and GalNAc-T6 were expressed in the endometrium of all groups, with no significant changes observed during the menstrual cycle. The expression of GalNAc-T3 and GalNAc-T6 in ectopic endometrium was significantly lower than that in eutopic (P < 0.05) or control endometrium (P < 0.05), whereas there were no significant differences (P > 0.05) between eutopic and control endometria. Furthermore, the expression of GalNAc-T3 and GalNAc-T6 was significantly lower in patients with stage III/IV EMS compared to patients with stage I/II (P < 0.05). CONCLUSIONS: Both GalNAc-T3 and GalNAc-T6 expression levels were downregulated in ectopic endometrium, which may increase the adhesion and invasion of endometrial cells and contribute to the development of EMS. Moreover, we found a strong correlation between the expression of GalNAc-T3 and GalNAc-T6 and different stages of EMS.

[Effects of exogenous suppressor of cytokine signaling on cell apoptosis in ectopic endometrial stromal cells].

OBJECTIVE: To explore the effects of exogenous suppressor of cytokine signaling 3 (SOCS3) in Janus Kinase/Signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathways and examine the relationship between exogenous SOCS3 and cell proliferation and apoptosis in ectopic endometrial stromal cells. METHODS: Ectopic endometrial stromal cells from patients with histopathologically confirmed endometriosis were primarily cultured in vitro. Vimentin staining was used to identify the purity of endometrial stromal cells. Lentivirus containing SOCS3 and GFP (green fluorescent protein) recombinant (LV-SOCS3-GFP) or only GFP gene (LV-GFP) was used to transfect two groups of ectopic endometrial stromal cells from the same patient respectively. They were divided into experimental (EG) and negative (NC) control. The transfection efficiency of lentivirus was measured by GFP fluorescence expression under microscope. And the expressions of SOCS3, STAT3 and JAK2 mRNA and protein were analyzed by real-time polymerase chain reaction (PCR) and Western blot respectively. And phosphorylated JAK2 and STAT3 proteins (p-STAT3 and p-JAK2) were also analyzed by Western blot. Cell cycles and apoptosis were detected by flow cytometry. RESULTS: The transfection efficiency of lentivirus was over 80% at 72 h post-transfection. Compared with NC, EG showed a higher expression of SOCS3 mRNA (P < 0.001). SOCS3 protein level of EG was higher than NC while p-STAT3 protein of EG obviously lower than NC. STAT3, JAK2 and p-JAK2 proteins showed no difference between two groups. The percentage of apoptotic cells in EG was higher remarkably than NC (22.0 ± 1.3)% vs (4.4 ± 1.3)%, P < 0.01. Moreover, EG cells showed a G0/G1 arrest compared with NC (87.0 ± 3.7)% vs (76.0 ± 3.7)%, P < 0.05. CONCLUSION: Exogenous SOCS3 induces cell apoptosis and inhibits cell proliferation in ectopic endometrial stromal cells.

Identification of MKNK1 and TOP3A as ovarian endometriosis risk-associated genes using integrative genomic analyses and functional experiments.

The risk of endometriosis (EM), which is a common complex gynaecological disease, is related to genetic predisposition. However, it is unclear how genetic variants confer the risk of EM. Here, via Sherlock integrative analysis, we combined large-scale genome-wide association studies (GWAS) summary statistics on EM (N = 245,494) with a blood-based eQTL dataset (N = 1490) to identify EM risk-related genes. For validation, we leveraged two independent eQTL datasets (N = 769) for integration with the GWAS data. Thus, we prioritised 14 genes, including GIMAP4, TOP3A, and NMNAT3, which showed significant association with susceptibility to EM. We also utilised two independent methods, Multi-marker Analysis of GenoMic Annotation and S-PrediXcan, to further validate the EM risk-associated genes. Moreover, protein-protein interaction network analysis showed the 14 genes were functionally connected. Functional enrichment analyses further demonstrated that these genes were significantly enriched in metabolic and immune-related pathways. Differential gene expression analysis showed that in peripheral blood samples from patients with ovarian EM, TOP3A, MKNK1, SIPA1L2, and NUCB1 were significantly upregulated, while HOXB2, GIMAP5, and MGMT were significantly downregulated compared with their expression levels in samples from the controls. Immunohistochemistry further confirmed the increased expression levels of MKNK1 and TOP3A in the ectopic and eutopic endometrium compared to normal endometrium, while HOBX2 was downregulated in the endometrium of women with ovarian EM. Finally, in ex vivo functional experiments, MKNK1 knockdown inhibited ectopic endometrial stromal cells (EESCs) migration and invasion. TOP3A knockdown inhibited EESCs proliferation, migration, and invasion, while promoting their apoptosis. Convergent lines of evidence suggested that MKNK1 and TOP3A are novel EM risk-related genes.

RNAi-mediated blocking of ezrin reduces migration of ectopic endometrial cells in endometriosis.

Ezrin is a member of the ezrin-radixin-moesin (ERM) family of membrane-cytoskeletal linkage proteins. It is important for maintenance of cell shape, adhesion, migration and division. The overexpression of ezrin in some tumours is associated with increased cell migration that is mediated by the Rho/ROCK family of small GTPases. To investigate the role of ezrin in the migration of ectopic endometrial cells in endometriosis, we conducted real-time quantitative RT-PCR analysis of the eutopic and ectopic endometrium from women with endometriosis compared with those without the disease. RNAi, wound healing assays and western blot analysis of endometriotic cells were also included in this research. We found significantly higher levels of mRNA expression of ezrin (0.42 versus 0.27, P < 0.05), RhoA (0.99 versus 0.74, P < 0.05), RhoC (0.79 versus 0.43, P < 0.005) and ROCK1 (0.68 versus 0.38, P < 0.005) in the ectopic endometrial cells compared with the eutopic endometrial cells in endometriosis. Blocking ezrin with small-interfering RNA reduced the migration of ectopic endometrial cells with decreased expression of RhoA (42.68%), RhoC (58.42%) and ROCK1 (59.88%). Our results indicate that the over-expression of ezrin in endometriosis may play a significant role in the migration of endometrial cells of endometriosis, and the RhoC/Rock pathway may provide a promising treatment target.

Corrigendum to 'Endometrial membrane organoids from human embryonic stem cell combined with the 3D Matrigel for endometrium regeneration in asherman syndrome' [Bioactive Mater. 6 (2021) 3935-3946].

[This corrects the article DOI: 10.1016/j.bioactmat.2021.04.006.].

Endometrial membrane organoids from human embryonic stem cell combined with the 3D Matrigel for endometrium regeneration in asherman syndrome.

Asherman's syndrome (AS), a leading cause of uterine infertility worldwide, is characterized by scarring of the uterine surfaces lacking endometrial epithelial cells, which prevents endometrial regeneration. Current research on cell therapy for AS focuses on mesenchymal and adult stem cells from the endometrium. However, insufficient number, lack of purity, and rapid senescence of endometrial epithelial progenitor cells (EEPCs) during experimental processes restrict their use in cell therapies. In this study, we induced human embryonic stem cells-9 (H9-ESC) into EEPCs by optimizing the induction factors from the definitive endoderm. EEPCs, which act as endometrial epithelial cells, accompanied by human endometrial stromal cells provide a niche environment for the development of endometrial membrane organoids (EMOs) in an in vitro 3D culture model. To investigate the function of EMOs, we transplanted tissue-engineered constructs with EMOs into an in vivo rat AS model. The implantation of EMOs into the damaged endometrium facilitates endometrial regeneration and angiogenesis. Implanting EMOs developed from human embryonic stem cells into the endometrium might prove useful for "endometrial re-engineering" in the treatment of Asherman's syndrome.

LncRNA MEG3-210 regulates endometrial stromal cells migration, invasion and apoptosis through p38 MAPK and PKA/SERCA2 signalling via interaction with Galectin-1 in endometriosis.

BACKGROUND: Endometriosis is a benign gynaecological disease with malignant characteristics that severely affects women's quality of life. Long noncoding RNA maternally expressed gene 3 (LncRNA MEG3) is a tumour suppressor that is downregulated in various cancer cells and tissues, and regulates multiple biological processes. Emerging studies have revealed that the interactions between MEG3 and proteins are involved in disease progression. Galectin-1 affects cell motility, signal transduction and vascularization, and is overexpressed in endometriosis. Our study is the first to explore the role of MEG3-210 transcript in endometriosis and to reveal the regulatory mechanism mediated by the interaction between MEG3-210 and Galectin-1. MATERIALS AND METHODS: Endometrial tissues and sera from patients with endometriosis and controls were collected. qRT-PCR was performed to detect the expression of MEG3-210 in the endometrium and endometrial stromal cells (ESCs). The CCK-8 assay, the Transwell assay, flow cytometry and animal models were conducted to evaluate the functions of MEG3-210 in vitro and in vivo. Bioinformatic analysis, Western blot assays, RNA-pull down assays and RNA immunoprecipitation were used to explore the potential mechanism of MEG3-210 in endometriosis. RESULTS: Our results showed that MEG3-210 expression was lower in the eutopic endometrium of women with endometriosis. MEG3-210 downregulation promoted ESCs migration, invasion, anti-apoptosis in vitro and growth of endometriotic lesions in vivo. Furthermore, MEG3-210 downregulation could activate p38 mitogen-activated protein kinase (p38 MAPK) and inhibit cAMP-dependent protein kinase A/sarcoplasmic reticulum Ca2+ ATPase 2 (PKA/SERCA2) signalling, which was mediated by Galectin-1. The protein levels of Galectin-1 in patients with endometriosis were elevated, and Galectin-1 siRNA could reduce the size of lesions. CONCLUSION: MEG3-210 regulates ESCs through p38 MAPK and PKA/SERCA signalling via interaction with Galectin-1. The novel regulatory mechanism may provide new insights into drug therapy and the diagnosis of endometriosis.

Crystallization and preliminary X-ray analysis of the splice variant of human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9-2).

Human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9), a subunit of an Elongin C-cullin-SOCS box (ECS) E3 ubiquitin ligase complex, is believed to be involved in specific substrate-recognition for ubiquitination and degradation. In fact, this specific substrate-recognition is determined by the ankyrin repeats of hASB9 protein. Here, we have cloned and overexpressed the hASB9-2, the splice variant of hASB9 with only one ankyrin repeat domain, as a 6His-tagged recombinant protein in Escherichia coli. The purified hASB9-2 protein was crystallized by the hanging-drop vapor-diffusion technique and diffracted to 2.2A resolution. The data showed that the cubic hASB9-2 crystal belongs to space group P4(3)32 with unit-cell parameters (a=b=c=129.25A, alpha=beta=gamma=90 degrees). An asymmetric unit in the crystal was assumed to contain one protein molecule giving the Matthews Coefficient factor of 2.81 and the solvent content of 56.3%.

Crystallization and preliminary X-ray analysis of the splice variant of human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9-2).

Human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9), a subunit of an Elongin C-cullin-SOCS box (ECS) E3 ubiquitin ligase complex, is believed to be involved in specific substrate-recognition for ubiquitination and degradation. In fact, this specific substrate-recognition is determined by the ankyrin repeats of hASB9 protein. Here, we have cloned and overexpressed the hASB9-2, the splice variant of hASB9 with only one ankyrin repeat domain, as a 6His-tagged recombinant protein in Escherichia coli. The purified hASB9-2 protein was crystallized by the hanging-drop vapor-diffusion technique and diffracted to 2.2A resolution. The data showed that the cubic hASB9-2 crystal belongs to space group P4(3)32 with unit-cell parameters (a=b=c=129.25A, alpha=beta=gamma=90 degrees ). An asymmetric unit in the crystal was assumed to contain one protein molecule giving the Matthews Coefficient factor of 2.81 and the solvent content of 56.3%.

Cloning, expression, and characterization of a thermostable PAP2L2, a new member of the type-2 phosphatidic acid phosphatase family from Geobacillus toebii T-85.

Most members of the type-2 phosphatidic acid phosphatase (PAP2) superfamily are integral membrane phophatases involved in lipid-related signal transduction and metabolism. Here we describe the cloning of a novel gene from Geobacillus toebii T-85, encoding a PAP2-like protein, Gtb PAP2L2, which contains 212 amino acids and shows a limited homology to other known PAP2s, especially at conserved phosphatase motifs, and a similar six-transmembrane topology structure. This enzyme was expressed, and purified in Escherichia coli. Recombinant Gtb PAP2L2s from the membrane fractions were solublized with 0.3% (v/v) Triton X-100 and purified by Ni(2+) affinity chromatography. The purified enzyme showed broad substrate specificity to phosphatidic acid, diacylglycerol pyrophosphate, and lysophosphatidic, but preferred phosphatidic acid and diacylglycerol pyrophosphate in vitro. Gtb PAP2L2 is a thermal stable enzyme with a half-life of 30 min at 60 degrees C. The enzyme was strongly inhibited by 1% SDS, 10 mM veranda, and Zn(2+), whereas it was independent of the Mg(2+) ion, and insensitive to N-ethylmaleimide. The purified recombinant Gtb PAP2L2 was catalytically active and highly stable, making it ideal as a candidate on which to base further PAP2 structure/function studies.

Estrogen nuclear receptors affect cell migration by altering sublocalization of AQP2 in glioma cell lines.

Glioblastomas are capable of infiltrating into neighboring brain tissues. The prognosis of a male patient is worse than that of women. Here, we demonstrate the effects of estrogen on invasion of glioma cells via regulating estrogen nuclear receptors (ERα and ERß) combined with aquaporin 2 (AQP2). In our study, we conclude that AQP2 was located mainly in the nuclei of the glioma cell lines and is capable of inhibiting cell invasion. According to the gene ontology analysis, out of 138 screened genes, three genes of ankyrin repeat and FYVE domain containing 1 (ANKFY1), lymphocyte transmembrane adaptor 1 (LAX1), and latent transforming growth factor beta-binding protein 1 (LTBP1) were found to be regulating the ERα and ERß. The expression of ERα was found to be high, whereas the expression of both ERß and AQP2 was low in glioma cells from patient tissues and glioblastoma cell lines. The expression levels of AQP2, ANKFY1, LAX1, and LTBP1 were upregulated by both ERα small interfering RNA (siRNA) and overexpression of ERß. AQP2 inhibition of cell invasion was inversely influenced by LAX1siRNA. The luciferase report system indicated that AQP2 promoted the transcriptional activity of LAX1 and inhibited cell invasion. These data suggest that ERß may function as AQP promoter in the nucleus to sustain cells' stability by promoting AQP production, while ERα acts as an antagonist of AQP2. The ratio between ERα and ERß is likely to affect the distribution of AQP2 in the nucleus. Low level of ERß reduces the inhibition of invasion of glioma cells influenced by high level of LAX1 expression, leading to an increase in the invasion ability of glioma cells.

ZNF435, a novel human SCAN-containing zinc finger protein, inhibits AP-1-mediated transcriptional activation.

Zinc finger transcription factor genes are a significant fraction of the genes in the vertebrate genome. Here we report the isolation and characterization of a human zinc finger-containing gene, ZNF435, from a fetal brain cDNA library. ZNF435 cDNA is 1290 base pairs in length and contains an open reading frame encoding 349 amino acids with four C2H2-type zinc fingers at its carboxyl terminus and a SCAN motif at its amino terminus. RT-PCR results showed that ZNF435 was expressed in all tested tissues. A ZNF435-GFP fusion protein was located in the nucleus and the four zinc fingers acted as nuclear localization signals (NLSs). ZNF435 was found to be capable of homo-association, and this effect was independent of its zinc fingers. Furthermore, ZNF435 proved to be a transcription repressor as its overexpression in AD293 cells inhibited the transcriptional activities of AP-1.

A novel splice variant of human XRN2 gene is mainly expressed in blood leukocyte.

The XRN2 gene (XRN2a) is the human homologue of the Saccharomyces cerevisiae RAT1 gene, which encodes a nuclear 5'-->3' exoribonuclease, and is essential for RNA metabolism and cell viability. Xrn2p/Rat1p, product of XRN2/RAT1 gene, functions in the mRNA degradation and processing of rRNAs and small nucleolar RNAs (snoRNAs) in the nucleus. Here we describe the cloning and characterization of a novel splice variant of the human XRN2 gene (XRN2b). The 3271-bp cDNA encodes a putative protein with 907 amino acid residues, which shares high homology with mouse DHM1 protein. RT-PCR analysis showed that XRN2b was mainly expressed in blood leukocyte tissue, while XRN2a was detected in several human tissues and in human tumor tissues.

Crystal structure of Human ASB9-2 and substrate-recognition of CKB.

Human ankyrin repeat and suppressor of cytokine signaling box protein 9 (hASB9) is a specific substrate-recognition subunit of an elongin C-cullin-SOCS box E3 ubiquitin ligase complex. It recognizes its substrate, brain type creatine kinase (CKB), using the ankyrin repeat domain; and facilitates the polyubiquitination of CKB to mediate proteasomal degradation through the SOCS box domain. HASB9-2 is an isoform of hASB9 that contains one ankyrin repeat domain. In this study, the crystal structure of hASB9-2 is shown at 2.2-Å resolution using molecular replacement. Overall, hASB9-2 forms a slightly curved arch with a characteristic L-shaped cross-section. Amino acid substitution analysis based on docking experiments revealed that His103 and Phe107 in hASB9-2 are essential for binding to CKB. Analysis of truncation mutants demonstrated that the first six ankyrin repeats along with the N-terminal region of hASB9-2 contribute to the interaction with CKB.

An unannotated alpha/beta hydrolase superfamily member, ABHD6 differentially expressed among cancer cell lines.

Abhydrolase domain containing (Abhd) gene was a small group belongs to alpha/beta hydrolase superfamily. Known members of this group are all found to be involved in important biochemical processes and related to various diseases. In this paper, we report the tissue distribution, subcellular location and differential distribution among cancer cell lines of Abhd6, one unannotated member of this group.

Cloning and characterization of a gene encoding the human putative ubiquitin conjugating enzyme E2Z (UBE2Z).

Ubiquitination, the covalent attachment of the protein ubiquitin (Ub) to other cellular proteins, has been implicated in a number of important physiological processes. ubiquitin conjugating enzyme (E2) plays an important role in the ubiquitin system. Here we report the research about a human putative ubiquitin conjugating enzyme gene, UBE2Z. The length of UBE2Z cDNA is 3054 base pairs and contains an open reading frame encoding 246 amino acids. The UBE2Z gene was mapped to human chromosome 17q21.32 and consisted of 6 exons. RT-PCR showed that UBE2Z was widely expressed in human tissues, especially high in placenta, pancreas, spleen and testis. The UBE2Z-GFP fusion protein was located in both nucleus and cytoplasm of AD293 cells.

Identification and characterization of human uracil phosphoribosyltransferase (UPRTase).

Uracil phosphoribosyltransferase, which catalyzes the conversion of uracil and 5-phosphoribosyl-1-R-diphosphate to uridine monophosphate, is important in the pyrimidine salvage pathway and is an attractive target for rational drug design by incorporation of prodrugs that are lethal to many parasitic organisms specifically. So far, uracil phosphoribosyltransferase has been reported in Arabidopsis thaliana only, not in mammals. In this study, a novel uracil phosphoribosyltransferase family cDNA encoding a 309 amino acid protein with a putative uracil phosphoribosyltransferase domain was isolated from the human fetal brain library. It was named human UPRTase (uracil phosphoribosyltransferase). The ORF of human UPRTase gene was cloned into pQE30 and expressed in Escherichia coli M15. The protein was purified by Ni-NTA affinity chromatography, but UPRTase activity could not be detected by spectrophotometry. RT-PCR analysis showed that human UPRTase was strongly expressed in blood leukocytes, liver, spleen, and thymus, with lower levels of expression in the prostate, heart, brain, lung, and skeletal muscle. Subcellular location of UPRTase-EGFP fusion protein revealed that human UPRTase was distributed in the nucleus and cytoplasm of AD293 cells. Evolutional tree analyses of UPRTases or UPRTase-domain-containing proteins showed that UPRTase was conserved in organisms. UPRTases of archaebacteria or eubacterium had UPRTase activity whereas those higher than Caenorhabditis elegans, which lacked two amino acids in the uracil-binding region, had no UPRTase activity. This means that human UPRTase may have enzymatic activity with another, unknown, factor or have other activity in pyrimidine metabolism.

Molecular cloning and characterization of a novel human gene containing 4 ankyrin repeat domains.

Ankyrin repeat, one of the most important protein motifs, plays a wide variety of roles in protein-protein interactions and in the signal pathways. Via large-scale sequencing, a novel 941-bp gene was isolated from an 18-week old human fetal brain cDNA library. It encodes a putative protein of 158 amino acid residues with four conserved ankyrin repeat domains. It displays a high degree of homology with rat low-density lipoprotein receptor-related protein 2-binding protein (Lrp2bp), and was therefore was named hLrp2bp (human Lrp2bp). The hLrp2bp gene was located in chromosome 4q35 and the conserved ankyrin repeat domains were located between amino acid residues 10 and 116. RT-PCR revealed that hLrp2bp was mainly expressed in the human testis, small intestine, colon and blood leukocytes, and in human pancreatic adenocarcinoma cells. A HEK293 cell was transfected with the ORF of hLrp2bp, and analyses showed that the protein was distributed both in the cytoplasm and nucleus.