Nuclear import of the thyroid hormone receptor α1 is mediated by importin 7, importin ß1, and adaptor importin α1.

The thyroid hormone receptor α1 (TRα1) is a nuclear receptor for thyroid hormone that shuttles rapidly between the nucleus and cytoplasm. Our prior studies showed that nuclear import of TRα1 is directed by two nuclear localization signals, one in the N-terminal A/B domain and the other in the hinge domain. Here, we showed using in vitro nuclear import assays that TRα1 nuclear localization is temperature and energy-dependent and can be reconstituted by the addition of cytosol. In HeLa cells expressing green fluorescent protein (GFP)-tagged TRα1, knockdown of importin 7, importin ß1 and importin α1 by RNA interference, or treatment with an importin ß1-specific inhibitor, significantly reduced nuclear localization of TRα1, while knockdown of other importins had no effect. Coimmunoprecipitation assays confirmed that TRα1 interacts with importin 7, as well as importin ß1 and the adapter importin α1, suggesting that TRα1 trafficking into the nucleus is mediated by two distinct pathways.

Multiple exportins influence thyroid hormone receptor localization.

The thyroid hormone receptor (TR) undergoes nucleocytoplasmic shuttling and regulates target genes involved in metabolism and development. Previously, we showed that TR follows a CRM1/calreticulin-mediated nuclear export pathway. However, two lines of evidence suggest TR also follows another pathway: export is only partially blocked by leptomycin B (LMB), a CRM1-specific inhibitor; and we identified nuclear export signals in TR that are LMB-resistant. To determine whether other exportins are involved in TR shuttling, we used RNA interference and fluorescence recovery after photobleaching shuttling assays in transfected cells. Knockdown of exportins 4, 5, and 7 altered TR shuttling dynamics, and when exportins 5 and 7 were overexpressed, TR distribution shifted toward the cytosol. To further assess the effects of exportin overexpression, we examined transactivation of a TR-responsive reporter gene. Our data indicate that multiple exportins influence TR localization, highlighting a fine balance of nuclear import, retention, and export that modulates TR function.

Multicenter study of human papillomavirus and the human papillomavirus vaccine: knowledge and attitudes among people of African descent.

OBJECTIVE: To compare knowledge and attitudes of human papillomavirus (HPV) and the vaccine between different cultures of African descent. METHODS: A cross-sectional survey of 555 African-Americans and Afro-Caribbeans residing in the US and the Bahamas (BHM) was conducted. RESULTS: General knowledge about HPV and the HPV vaccine differed between the two countries significantly. Bahamian respondents were less likely to have higher numbers of correct knowledge answers when compared to Americans (Adjusted Odds Ratio [Adj. OR] 0.47, 95% Confidence Interval [CI] 0.30-0.75). Older age, regardless of location, was also associated with answering fewer questions correctly (Adj. OR 0.61, 95% CI 0.40-0.92). Attitudes related to HPV vaccination were similar between the US and BHM, but nearly 80% of BHM respondents felt that children should not be able to receive the vaccine without parental consent compared to 57% of American respondents. CONCLUSIONS: Grave lack of knowledge, safety and cost concerns, and influence of parental restrictions may negatively impact vaccine uptake among African-American and Afro-Caribbean persons. Interventions to increase the vaccine uptake in the Caribbean must include medical provider and parental involvement. Effective strategies for education and increasing vaccine uptake in BHM are crucial for decreasing cervical cancer burden in the Caribbean.

Kruppel-like factor 1 (KLF1), KLF2, and Myc control a regulatory network essential for embryonic erythropoiesis.

The Krüppel-like factor 1 (KLF1) and KLF2 positively regulate embryonic ß-globin expression and have additional overlapping roles in embryonic (primitive) erythropoiesis. KLF1(-/-) KLF2(-/-) double knockout mice are anemic at embryonic day 10.5 (E10.5) and die by E11.5, in contrast to single knockouts. To investigate the combined roles of KLF1 and KLF2 in primitive erythropoiesis, expression profiling of E9.5 erythroid cells was performed. A limited number of genes had a significantly decreasing trend of expression in wild-type, KLF1(-/-), and KLF1(-/-) KLF2(-/-) mice. Among these, the gene for Myc (c-Myc) emerged as a central node in the most significant gene network. The expression of the Myc gene is synergistically regulated by KLF1 and KLF2, and both factors bind the Myc promoters. To characterize the role of Myc in primitive erythropoiesis, ablation was performed specifically in mouse embryonic proerythroblast cells. After E9.5, these embryos exhibit an arrest in the normal expansion of circulating red cells and develop anemia, analogous to KLF1(-/-) KLF2(-/-) embryos. In the absence of Myc, circulating erythroid cells do not show the normal increase in α- and ß-like globin gene expression but, interestingly, have accelerated erythroid cell maturation between E9.5 and E11.5. This study reveals a novel regulatory network by which KLF1 and KLF2 regulate Myc to control the primitive erythropoietic program.

Recruitment of the oncoprotein v-ErbA to aggresomes.

Aggresome formation, a cellular response to misfolded protein aggregates, is linked to cancer and neurodegenerative disorders. Previously we showed that Gag-v-ErbA (v-ErbA), a retroviral variant of the thyroid hormone receptor (TRα1), accumulates in and sequesters TRα1 into cytoplasmic foci. Here, we show that foci represent v-ErbA targeting to aggresomes. v-ErbA colocalizes with aggresomal markers, proteasomes, hsp70, HDAC6, and mitochondria. Foci have hallmark characteristics of aggresomes: formation is microtubule-dependent, accelerated by proteasome inhibitors, and they disrupt intermediate filaments. Proteasome-mediated degradation is critical for clearance of v-ErbA and T(3)-dependent TRα1 clearance. Our studies highlight v-ErbA's complex mode of action: the oncoprotein is highly mobile and trafficks between the nucleus, cytoplasm, and aggresome, carrying out distinct activities within each compartment. Dynamic trafficking to aggresomes contributes to the dominant negative activity of v-ErbA and may be enhanced by the viral Gag sequence. These studies provide insight into novel modes of oncogenesis across multiple cellular compartments.

Knowledge about human papillomavirus and the HPV vaccine--a survey of the general population.

BACKGROUND: The United States (US) Food & Drug Administration (FDA) recently approved a human papillomavirus (HPV) vaccine with the purpose of reducing the risk of cervical cancers caused by HPV 16 and HPV 18. It is important that the general population be educated about HPV and the HPV vaccine in order to make the appropriate decision whether or not to vaccinate against this virus. Participants from the adult US general population of Pittsburgh, Pennsylvania, USA and Hampton, Virginia, USA (18+ years old) were surveyed to determine their knowledge about HPV and the HPV vaccine, and to evaluate their perception of the vaccine efficacy and safety. RESULTS: We report herein preliminary data for 202 participants. Fifty-five percent (55%) of the study population was White, 45% Black, and 1% was from other ethnic groups or did not disclose their ethnicity. A large proportion of participants had heard of the human papillomavirus (overall population: 93.6%; Pittsburgh: 95%; Hampton: 90%). Participants of African descent were slightly less aware of HPV than Whites (Black 89% vs. Whites 97%, p > 0.1). Although the majority of participants knew that HPV caused cervical cancer (84%), Whites were more informed than Black participants (91% vs. 73%, p = 0.044). Eighty-seven percent (87%) of participants had heard of the HPV vaccine (Pittsburgh: 92% and Hampton: 74%, p = 0.029); a higher proportion of Whites were aware of the vaccine when compared with Blacks (93% vs. 76%, p = 0.031). However, only 18% of the population knew that the current FDA-approved vaccine protected against genital warts and most cervical cancer (20% of Blacks and 16% of Whites, p > 0.1). CONCLUSION: These data suggest that although the general population might be aware of HPV and the HPV vaccine, knowledge of the benefits of the HPV vaccination may not be apparent. Knowledge of HPV and the HPV vaccine could result in a likely choice of HPV vaccination and would subsequently reduce the incidence of cervical cancer.

Comparison of knowledge and attitudes toward cancer among African Americans.

BACKGROUND: It has been noted that the African American population in the U.S. bears disproportionately higher cancer morbidity and mortality rates than any racial and ethnic group for most major cancers. Many studies also document that decreased longevity is associated with low educational attainment and other markers of low socioeconomic status (SES), both of which are prevalent in African American communities across the nation. Evidence suggests that this phenomenon may be due to attitudes that reflect a lack of knowledge surrounding facts about cancer awareness and prevention. This study was designed to yield data concerning the general population's attitudes toward cancer, taking into consideration racial and/or socioeconomic differences in the population studied. RESULTS: Two hundred and fifteen subjects participated in the survey, of which 74% (159/215) defined themselves as African-American, 20% were White, and 6% were of other races. While only 38% of the study population was able to identify at least 5 risk factors associated with cancer, a lower proportion of African Americans identified at least 5 risk factors than whites (34% vs. 53%, p = 0.03). In addition, a slightly higher percentage of African Americans (10%) were not aware of the definition of a clinical trial when compared to whites (8%, p > 0.1). Of those aware of the definition of a clinical trial, African Americans were more reluctant to participate in clinical trials, with 53% answering no to participation compared to 15% of whites (p = 0.002). CONCLUSION: When comparing results to a similar study conducted in 1981, a slight increase in cancer knowledge in the African American population was observed. Our results suggest that while knowledge of cancer facts has increased over the years amongst the general population, African Americans and lower income populations are still behind. This may affect their risk profile and cancer early detection.