Pathogenicity of Autoantibodies in Anti-p200 Pemphigoid

Recently, the C-terminus of laminin γ1 has been identified as target antigen in anti-p200 pemphigoid and the disease was renamed as anti-laminin γ1 pemphigoid. However, the pathogenic relevance of these autoantibodies has not yet been demonstrated. Therefore, we employed an ex vivo model of autoantibody-mediated leukocyte-dependent neutrophil activation and dermal-epidermal separation (DES) using cryosections of human skin. We showed that anti-p200 pemphigoid sera (n = 7) induced DES in a time-dependent manner, in contrast to sera from healthy controls. Furthermore, laminin γ1-specific IgG and serum depleted from anti-laminin γ1 reactivity were generated using the recombinant C-terminus of laminin γ1 (LAMC1-term; amino acids 1364 to 1609). Interestingly, both fractions labeled the dermal-epidermal-junction (DEJ) by indirect immunofluorescence microscopy on human foreskin and recognized a 200 kDa protein by immunoblotting with dermal extract. Human and rabbit IgG against LAMC1-cterm failed to attract neutrophils at the DEJ and to induce DES. In contrast, patient serum depleted from LAMC1-cterm reactivity led to the same extent of DES as non-depleted IgG. Repeated injection of rabbit anti-murine LAMC1-cterm IgG into both neonatal and adult C57BL/6mice as well as repetitive immunization of various mouse strains with murine LAMC1-cterm failed to induce macro- and microscopic lesions. In all mice, circulating anti-LAMC1-cterm antibodies were present, but only in some mice, IgG deposits were seen at the DEJ. We conclude that autoantibodies in anti-p200 pemphigoid sera are pathogenic while pathogenicity is not mediated by autoantibodies against laminin γ1. Further studies are needed to identify the pathogenically relevant autoantigen in anti-p200 pemphigoid.     

Primary biliary cirrhosis sera recognize not only gp210 but also proteins of the p62 complex bearing N-acetylglucosamine residues from rat liver nuclear envelope

We have recently observed reactivity of primary biliary cirrhosis (PBC) sera with several proteins bearing N-acetylglucosamine residues from rat liver nuclear envelopes. The aim of this study was to characterize the reactive antigens. Sera from 31 patients with PBC, 30 with rheumatoid arthritis (RA) and 30 with Sjögren's syndrome (SS) were examined. Rim-like immunofluorescence staining was observed in 15 of 31 (48%) sera from patients with PBC, in 1 of 30 with RA and in 1 of 30 with SS. Upon immunoblotting using preparations of whole rat liver nuclear envelopes and their Triton X 100-KCl extract as antigen souces, a 200 kDa protein band was observed in 9 of sera with PBC. Furthermore, upon immunoblotting using the wheat germ aggulutinin-bound fraction of rat liver envelope as antigen, 62, 60 and 54 kDa protein bands corresponding to components of the p62 complex in the nuclear pore complex (Kita et al. Biochem. 113, 377–382) were observed in 7, 5 and 6 samples respectively, of the 31 PBC sera. Our data suggest that PBC sera recognize not only the 210 kDa protein but also the p62 complex proteins.Abbreviations ANA antinuclear antibody - AMA anti-mitochondrial antibodies - IF immunofluorescence - LAP2 lamina-associated polypeptide 2 - LBR lamin B receptor - anti-NBP 60 anti-nuclear localization signal binding protein 60 - NE nuclear envelope - NPC nuclear pore complex - PBC primary biliary cirrhosis - RA rheumatoid arthritis - SLE systemic lupus erythematosus - SS Sjögren's syndrome - WGA wheat germ agglutinin     

核孔蛋白p62促进非受体酪氨酸激酶c-Abl进入细胞核

非受体酪氨酸激酶c-Abl广泛表达于各组织细胞中,其序列高度保守,它的亚细胞定位与其功能密切相关。c-Abl借助其C端的3个核定位信号（NLS）和1个核输出信号（NES）完成细胞核一细胞质问的穿梭过程。关于c-Abl核-质穿梭的详细机制还不清楚。通过酵母双杂交系统,以人类Ib型c-Abl作为诱饵蛋白进行HeLa细胞eDNA文库的筛选,获得了可能在c-Abl核-质穿梭过程中具有调控怍用核孔蛋白p62。核孔复合物（NPC）是大分子物质进行核-质运输的惟一通道,p62是NPC的重要组成部分,它位于中央通道内侧,在许多物质的核-质穿梭过程中具有调节作用。免疫共沉淀和体外结合实验证实,c-Abl和p62之间具有相互作用,而且这种相互作用是通过c-Abl的SH3结构域与p62的P299位点之间的结合实现的;p62可被c-Abl部分磷酸化此外,在293和DKO细胞株中共转染c-Abl和p62,发现核内的c-Abl分布增多。以上结果表明,p62具有促进e-Abl进入细咆核的作用。     

Serum anti-p53 autoantibodies in primary resected non-small-cell lung carcinoma

 Mutated p53 proteins accumulate in the nuclei of tumor cells, and anti-p53 autoantibodies are found in the sera of patients with non-small-cell lung carcinoma (NSCLC). We analyzed the correlation among serum anti-p53 autoantibodies, immunohistochemical staining for p53, and clinical features (age, gender, smoking history, histological type, differentiation, stage, T factor, tumor size, and N factor) in resected non-small-cell lung carcinomas. A total of 62 cases of resected NSCLC were studied (43 men and 19 women; 33 adenocarcinomas, 21 squamous cell carcinomas, 8 large-cell carcinomas). Preoperative serum titers of anti-p53 autoantibodies were detected in 13/62 cases (21.0%). A correlation between histological type and positive titers of serum p53 autoantibodies was seen (large-cell carcinoma versus squamous cell carcinoma and adenocarcinoma, P = 0.031, χ²-test). Out of 25 cases, 10 (40%) with positive immunohistochemical staining for p53 had positive titers, whereas 3 positive titers were found in 37 patients with negative immunohistochemical staining for p53 (P = 0.0025, χ²-test). Serum titers of anti-p53 autoantibodies were present in approximately 20% of the cases of NSCLC, and overexpression of p53 protein in tumor cells was detectable in approximately 40%. Serum anti-p53 autoantibodies may be a clinical parameter for the presence of p53 mutations and p53 overexpression in NSCLC patients. Received: 22 October 1997 / Accepted: 22 April 1998     

Comparative epitope mapping of murine monoclonal and human autoantibodies to human PDH-E2, the major mitochondrial autoantigen of primary biliary cirrhosis.

Immunization with recombinant human pyruvate dehydrogenase (PDH)-E2, the major autoantigen of primary biliary cirrhosis, readily induces a vigorous murine antibody response but does not generate hepatic disease. To determine the fine specificity of this response, 18 mAb were generated from three strains of mice and the reactive epitopes mapped. An initial examination of mAb suggested that they behaved similarly to the antimitochondrial autoantibodies in primary biliary cirrhosis (PBC) because i) all polyclonal antisera and 2 of 18 mAb reacted with all species of mammalian PDH-E2 examined including mouse PDH-E2, ii) 15 of 18 mAb inhibited PDH enzyme function, and iii) the reactivity of mAb toward rPDH-E2 were blocked by PBC sera. However, fine examination of the reactive sequences of the PDH-E2 complex revealed that antibodies identical to those in PBC patients were not produced by experimental immunization. In contrast to PBC, none of the mAb or murine polyclonal sera were able to react with protein X, a lipoic acid-containing component of the PDH complex previously shown to cross-react with PDH-E2 when probed with PBC sera. Although the epitopes for 12 mAb were localized within the inner lipoyl domain, none reacted with mouse PDH-E2 or cross-reacted with the outer lipoyl domain as observed in PBC. In addition, the epitopes of the two mAb which did react with all mammalian species of mitochondria were not localized within the PBC epitope. These findings indicate the highly immunogenic nature of the inner lipoyl domain of PDH-E2. The inability to elicit antibodies of the same specificity in mice, considered together with the highly localized autoantibody response in humans, suggests that antimitochondrial autoantibodies are most likely the result of specific breakdown of tolerance to a unique autoepitope.     

Mapping of multiple B cell epitopes on the 70-kilodalton autoantigen of the U1 ribonucleoprotein complex.

High titer IgG autoantibodies to the 70-kDa polypeptide component (p70) of the U1 ribonucleoprotein (RNP) complex occur in the sera of patients with mixed connective tissue disease, SLE, and related rheumatic diseases. To gain insight into the pathogenesis and diversity of this antibody response we have used recombinant DNA technology to map the linear B cell epitopes on p70. A full length 1.7-kb cDNA clone encoding p70 was isolated from a human placental library and restriction fragments or polymerase chain reaction-generated fragments of the gene subcloned into the bacterial expression vector pGEX. Purified fusion proteins representing specific regions of p70 were immunoblotted with a panel of 70 anti-(U1)RNP+ sera containing anti-p70 antibodies. Six epitopes, four major (A, B, C, and F) and two minor (D and E) were mapped and were located throughout the molecule. The anti-(U1)RNP sera displayed heterogeneity in their pattern of reactivity to the six epitopes although reactivity to epitope C was more frequently associated with SLE rather than mixed connective tissue disease. The identification of multiple B cell epitopes on p70 is consistent with the concept that this self Ag drives the autoantibody response.     

An evolutionarily conserved NPC subcomplex, which redistributes in part to kinetochores in mammalian cells

The nuclear pore complexes (NPCs) are evolutionarily conserved assemblies that allow traffic between the cytoplasm and the nucleus. In this study, we have identified and characterized a novel human nuclear pore protein, hNup133, through its homology with the Saccharomyces cerevisiae nucleoporin scNup133. Two-hybrid screens and immunoprecipitation experiments revealed a direct and evolutionarily conserved interaction between Nup133 and Nup84/Nup107 and indicated that hNup133 and hNup107 are part of a NPC subcomplex that contains two other nucleoporins (the previously characterized hNup96 and a novel nucleoporin designated as hNup120) homologous to constituents of the scNup84 subcomplex. We further demonstrate that hNup133 and hNup107 are localized on both sides of the NPC to which they are stably associated at interphase, remain associated as part of a NPC subcomplex during mitosis, and are targeted at early stages to the reforming nuclear envelope. Throughout mitosis, a fraction of hNup133 and hNup107 localizes to the kinetochores, thus revealing an unexpected connection between structural NPCs constituents and kinetochores. Photobleaching experiments further showed that the mitotic cytoplasm contains kinetochore-binding competent hNup133 molecules and that in contrast to its stable association with the NPCs the interaction of this nucleoporin with kinetochores is dynamic.     

Identification and characterization of mitochondria autoantigens in progressive systemic sclerosis: identity with the 72,000 dalton autoantigen in primary biliary cirrhosis

Sera from eight out of 62 (14.5%) patients with progressive systemic sclerosis (PSS) reacted by immunoblotting with a 72,000 dalton antigen and one, a patient with concomitant primary biliary cirrhosis (PBC), reacted with the 72,000 dalton and a 47,000 dalton antigen. Reactivity with these antigens was not seen with any of 111 control sera. The antigens with minor variations in m.w. were present in a variety of cultured cells and tissue homogenates from different species. Subcellular fractionation studies localized the antigens to the mitochondria. Of 19 sera from patients with other diseases selected for immunofluorescence staining for anti-mitochondria autoantibody, nine reacted with the 72,000 dalton antigen, seven reacted with both the 72,000 and 47,000 dalton antigens, and three reacted with the 47,000 dalton antigen. These results show that serum reactivity with the 72,000 dalton and 47,000 dalton mitochondria autoantigens is found with some patients with PSS. Because mitochondria autoantibodies that are reactive with the 72,000 dalton and 47,000 dalton polypeptides are also found in patients with PBC, the present finding provides additional support for the association of PSS with PBC. Prior absorption of rat liver homogenate with PBC sera removed PSS serum reactivity with a 63,000 dalton antigen, the equivalent 72,000 dalton antigen in rodents, and vice versa, showing that both PBC and PSS sera recognize the same antigen.     

Anti-La antibody production by MRL-1pr/1pr mice. Analysis of fine specificity

In evaluating the origin of autoantibodies, patterns of self-Ag recognition have been interpreted to reflect the relative role of Ag in stimulating a response. Few studies, however, have assessed whether human autoantibodies display patterns of autoantigen recognition similar to those of SLE-prone mice. In previous studies, anti-La antibodies from humans have been shown to bind multiple epitopes on recombinant human La Ag, including immunoreactivity with a large fragment, termed La C, representing the middle portion of the La sequence. We report herein for the first time that MRL-1pr mice also spontaneously produce antibodies to recombinant human La protein and resemble human autoantibodies in their reactivity with La C. To further investigate the fine specificity of this response, we tested for antibody binding to six synthetic La peptides representing sequences within La C. Whereas two of the synthetic La peptides reacted with MRL-1pr sera containing anti-La binding, low reactivity was observed with a large panel of human anti-La sera. Our results therefore show that patterns of La antigen recognition displayed by MRL-1pr antibodies differ from those of human autoantibodies, possibly reflecting differences between mouse and man in the induction of these responses.     

Saccharomyces cerevisiae Ndc1p Is a Shared Component of Nuclear Pore Complexes and Spindle Pole Bodies

We report a novel connection between nuclear pore complexes (NPCs) and spindle pole bodies (SPBs) revealed by our studies of the Saccharomyces cerevisiae NDC1 gene. Although both NPCs and SPBs are embedded in the nuclear envelope (NE) in yeast, their known functions are quite distinct. Previous work demonstrated that NDC1 function is required for proper SPB duplication (Winey, M., M.A. Hoyt, C. Chan, L. Goetsch, D. Botstein, and B. Byers. 1993. J. Cell Biol. 122:743–751). Here, we show that Ndc1p is a membrane protein of the NE that localizes to both NPCs and SPBs. Indirect immunofluorescence microscopy shows that Ndc1p displays punctate, nuclear peripheral localization that colocalizes with a known NPC component, Nup49p. Additionally, distinct spots of Ndc1p localization colocalize with a known SPB component, Spc42p. Immunoelectron microscopy shows that Ndc1p localizes to the regions of NPCs and SPBs that interact with the NE. The NPCs in ndc1-1 mutant cells appear to function normally at the nonpermissive temperature. Finally, we have found that a deletion of POM152, which encodes an abundant but nonessential nucleoporin, suppresses the SPB duplication defect associated with a mutation in the NDC1 gene. We show that Ndc1p is a shared component of NPCs and SPBs and propose a shared function in the assembly of these organelles into the NE.     

Identification and specificity of a cDNA encoding the 70 kd mitochondrial antigen recognized in primary biliary cirrhosis

Mitochondrial autoantibodies are characteristic of the disease primary biliary cirrhosis (PBC), but the immunoreactive mitochondrial antigens have not been defined. We used a rat liver cDNA library in lambda gt 11-Amp3 to clone a 1370-base pair insert that coded for a polypeptide reactive with PBC sera. This insert was subcloned for expression into pBTA224, a plasmid vector in the same reading frame as lambda-Amp3. A positive clone, designated pRMIT, that expressed a fused polypeptide of 160 kd, was recognized by 25 of 25 sera from patients with PBC and none of 96 sera from normal persons or patients with systemic lupus erythematosus, rheumatoid arthritis, or chronic active hepatitis. This fused polypeptide was shown to correspond with the 70 kd mitochondrial autoantigen by several experiments. First, lysates of pRMIT in J101 absorbed out the 70 kd reactivity of PBC sera when probed against fractionated placental mitochondria. Second, affinity-purified antisera reactive with the fused polypeptide also reacted with the 70 kd mitochondrial antigen. Third, such affinity-purified antisera produced the characteristic anti-mitochondrial pattern of immunofluorescence on tissue sections. Finally, immunization of BALB/c mice with the fused polypeptide elicited antibodies to mitochondria. These murine antibodies reacted with the 70 kd mitochondrial protein and also produced typical mitochondrial immunofluorescence on tissue sections. The nucleotide and amino acid sequence of the recombinant protein, which encodes for approximately a 48 kd protein, showed no significant homologies with known proteins, and there were no homologies with mitochondrial genomic DNA. The availability of a recombinant form of the 70 kd mitochondrial autoantigen will allow several definitive questions to be addressed in PBC, including identification of B cell epitopes, T cell recognition, and a model of PBC in mice.     

非洲猪瘟病毒p35蛋白作为诊断抗原的抗原性比较

为了筛选出酶联免疫吸附测定(Enzyme linked immunosorbent assay,ELISA)反应性最佳的非洲猪瘟病毒(African swine fever virus,ASFV)诊断抗原,通过建立ELISA方法,以杆状病毒昆虫细胞表达系统表达的ASFV p30蛋白诊断抗原为参照,首次探讨原核表达系统表...     

Wuchereria bancrofti: cloning and characterization of heat shock protein 70 from the human lymphatic filarial parasite

Heat shock protein 70 (HSP70) was identified as an immunodominant antigen by screening a Wuchereria bancrofti (Wb) microfilarial cDNA library with pooled Wb-infected sera, with 28% of the immunopositive clones coding for Wb-HSP70. The deduced amino acid sequence showed greater than 97 and 85% identity with HSP70 from filarial nematodes and humans, respectively. Recombinant HSP70 (74 kDa) and a recombinant protein from the C-terminal portion (43 kDa) also reacted with pooled Wb-infected sera, suggesting that the C-terminal region of HSP70 contains at least one antibody epitope. Brugia malayi L3 larvae showed increasing levels of HSP70 with increasing temperatures. Further, a polyclonal mouse anti-Wb-HSP70 antibody had reactivity to the HSP70 of cattle filarial parasite Settaria digitata and to human HSP70 derived from a Hep-2 cell line. Immune reactivity to Wb-HSP70 was strong, with uninfected non-endemic normal sera showing significantly greater reactions than sera from filaria-infected individuals. Both immunodominant self-HSP70 and HSP70 from other microbial infections may be primary targets for developing autoantibodies naturally.     

Annulate lamellae play only a minor role in the storage of excess nucleoporins in Drosophila embryos

The nuclear pore complexes (NPCs), multiprotein assemblies embedded in the nuclear envelope, conduct nucleo-cytoplasmic traffic of macromolecules. Mimics of NPCs, called annulate lamellae pore complexes (ALPCs), are usually found in cytoplasmic membranous stacks in oocytes and early embryonic cells. They are believed to constitute storage compartments for excess premade nucleoporins. To evaluate the extent to which ALPCs store nucleoporins in early embryonic cells we took advantage of syncytial Drosophila embryos, containing both AL and rapidly proliferating nuclei in the common cytoplasm. Electron microscopic morphometric analysis showed that the number of ALPCs did not decrease to compensate for the growing number of NPCs during syncytial development. We performed Western blot analysis to quantify seven different nucleoporins and analyzed their intraembryonal distribution by confocal microscopy and subcellular fractionation. Syncytial embryos contained a large maternally contributed stockpile of nucleoporins. However, even during interphases, only a small fraction of the excess nucleoporins was assembled into ALPCs, whereas the major fraction was soluble and contained at least one phosphorylated nucleoporin. We conclude that in Drosophila embryos ALPCs play only a minor role in storing the excess maternally contributed nucleoporins. Factors that may prevent nucleoporins from assembly into ALPCs are discussed.     

Evaluation of a Recombinant 27-kDa Outer Membrane Protein of Coxiella burnetii as an Immunodiagnostic Reagent

The 27-kDa outer membrane protein from eight strains of Coxiella burnetii was expressed in the pET-21c protein expression system. Two fusion proteins with molecular masses of 30 and 32 kDa were evident in all eight of the recombinants by SDS-PAGE and immunoblotting. A protein having an approximate size of 30 kDa was purified from the Escherichia coli lysates by one-step affinity purification. The utility of the purified recombinant protein in ELISA was also evaluated by testing its reactivity with human sera and comparing this reactivity with that of Nine Mile phase II antigen. All of the 40 IF-positive serum samples were ELISA-positive for both the Nine Mile phase II and recombinant antigens, and negative serum controls were negative for both antigens. These results suggest that ELISA with the 27-kDa recombinant antigen is a sensitive and specific method for detecting anti-C. burnetii antibodies in human sera.     

Reactivity of an HIV gag gene polypeptide expressed in E. coli with sera from AIDS patients and monoclonal antibodies to gag

A segment of the gag gene of the human immunodeficiency virus (HIV) (HTLV-IIIB strain), the virus which causes acquired immunodeficiency syndrome (AIDS), has been cloned into the bacterial expression vector, pCQV2, and mapped to the right-hand portion of the gag gene containing the carboxyl-terminal portion of p24 and the amino-terminal portion of p15. Nucleic-acid sequencing of the insert-vector junctions further defined the 5'-terminal nucleotide of HIV sequence as nucleotide 997 and the 3'-terminal nucleotide as 1696. When used in an enzyme-linked immunosorbent assay (ELISA) with sera from HIV-infected patients, the cloned antigen reacted with a subset of sera which were positive on a standard ELISA using whole virus as antigen. Western-blot screening of these sera with whole virus indicated that all p24-positive sera were positive with the clone, suggesting that the carboxyl-terminal portion of p24 contains a highly antigenic epitope(s). A serum which was p24-negative p15-positive by Western blot analysis was also highly reactive, indicating that a p15 epitope is present in the cloned antigen. Epitope mapping with a series of monoclonal antibodies to gag resulted in positive ELISA with 2 of 3 anti-p24, 0 of 1 anti-p15, and 0 of 1 anti-p17 Western-blot-positive monoclonal antibodies, suggesting that one of the anti-p24 monoclonal antibodies reacts with epitopes amino-terminal to those coded from nucleotide 997, two anti-p24 monoclonals react with epitopes carboxyl-terminal to those coded from nucleotide 997, and the anti-p15 monoclonal reacts with epitopes carboxyl-terminal to those coded from nucleotide 1696.     

Construction,expression and characterization of the engineered antibody against tumor surface antigen,p185^c—erbB—2

The c-erbB-2 proto-oncogene encodes a 185kD protein p185,which belongs to epidermal growth factor receptor family.Amplification of this gene has been shown to correlate with poor clinical prognosis for certain cancer patients.The monoclonal antibody A21 which directed against p185 specifically inhibits proliferation of tumor cells overexpressing p185,hence allows it to be a candidate for targeted therapy.In order to overcome several drawbacks of murine MAb,we cloned its VH and VL genes and constructed the single-chain FV(scFv)through a peptide linker.The recombinant scFv A21 was expressed in Escherichia coli and purified by the affinity column.Subsequently it was characterized by ELISA,Western blot,cell immunohistochemistry and FACS.All these assays showed the binding activity to extracellular domain(ECD)of p185.Based on those properties of scFvA21,we further constructed the scFv-Fc fusion molecule with a homodimer form and the recombinant product was expressed in mammalian cells.In a series of subsequent analysis this fusion protein showed identical antigen binding site and activity with the parent antibody.These anti-p185 engineered antibodies have promised to be further modified as a tumor targeting drugs,with a view of application in the diagnosis and treatment of human breast cancer.     

The incidence of the pituitary autoantibodies in Graves' disease

INTRODUCTION: It is known that in the sera of patients with Graves, Addison and other autoimmune endocrine diseases we can detect autoantibodies against pituitary antigens. The aim of the study was evaluation of pituitary autoantibodies in Graves' disease patients using immunoblotting methods. MATERIAL AND METHODS: Studies were performed in 32 Graves' disease patients, 25 women (age range: 31-67 yrs, median: 49.9 +/- 9.4) and 7 men (age range: 41-58 yrs, median: 51.0 +/- 7.1). All patients presented signs and symptoms typical of thyrotoxicosis. The diagnosis was confirmed by laboratory tests (TSH, fT(3), fT(4), TSH-R antibodies). Sera of control subjects were obtained from 10 healthy blood donors, 7 women, 3 men (age range 21-45 yrs, median: 30.6 +/- 7.1). Incidence of pituitary autoantibodies was assessed by polyacrylamide electrophoresis gel and western-blotting. Pituitary microsomes were obtained from human pituitary tissues by ultracentrifugation and solubilisation in 1% desoxycholic acid. RESULTS: In 23 sera from 32 we detected autoantibodies against pituitary microsomal antigens. 16 sera were reacting with 55 kDa antigen, 10 sera with 67 kDa, 6 sera with 60 kDa, 5 sera with 52 kDa and 4 sera with 105 kDa. It is important to note that 6 sera were reacting with 57 and 55 kDa, and 5 sera with 55, 60 and 67 kDa. CONCLUSIONS: In sera of Graves' disease patients autoantibodies against pituitary microsomal antigens can be frequently detected. The most frequent are antibodies against 55, 60 and 67 kDa antigens.     

Nucleoporin Nup62 maintains centrosome homeostasis

Centrosomes are comprised of 2 orthogonally arranged centrioles surrounded by the pericentriolar material (PCM), which serves as the main microtubule organizing center of the animal cell. More importantly, centrosomes also control spindle polarity and orientation during mitosis. Recently, we and other investigators discovered that several nucleoporins play critical roles during cell division. Here, we show that nucleoporin Nup62 plays a novel role in centrosome integrity. Knockdown of Nup62 induced mitotic arrest in G₂/M phases and mitotic cell death. Depletion of Nup62 using RNA interference results in defective centrosome segregation and centriole maturation during the G₂ phase. Moreover, Nup62 depletion in human cells leads to the appearance of multinucleated cells and induces the formation of multipolar centrosomes, centriole synthesis defects, dramatic spindle orientation defects, and centrosome component rearrangements that impair cell bi-polarity. Our results also point to a potential role of Nup62 in targeting gamma-tubulin and SAS-6 to the centrioles.