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1.
J Endocrinol ; 262(2)2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-38829257

RESUMO

Cells actively engaged in de novo steroidogenesis rely on an expansive intracellular network to efficiently transport cholesterol. The final link in the transport chain is STARD1, which transfers cholesterol to the enzyme complex that initiates steroidogenesis. However, the regulation of ovarian STARD1 is not fully characterized, and even less is known about the upstream cytosolic cholesterol transporters STARD4 and STARD6. Here, we identified both STARD4 and STARD6 mRNAs in the human ovary but only detected STARD4 protein since the primary STARD6 transcript turned out to be a splice variant. Corpora lutea contained the highest levels of STARD4 and STARD1 mRNA and STARD1 protein, while STARD4 protein was uniformly distributed across ovarian tissues. Cyclic AMP analog (8Br-cAMP) and phorbol ester (PMA) individually increased STARD1 and STARD4 mRNA along with STARD1 protein and its phosphoform in cultured primary human luteinized granulosa cells (hGCs). STARD6 transcripts and STARD4 protein were unresponsive to these stimuli. Combining lower doses of PMA and 8Br-cAMP blunted the 8Br-cAMP stimulation of STARD1 protein. Increasing cholesterol levels by blocking its conversion to steroid with aminoglutethimide or by adding LDL reduced the STARD4 mRNA response to stimuli. Sterol depletion reduced the STARD1 mRNA and protein response to PMA. These data support a possible role for STARD4, but not STARD6, in supplying cholesterol for steroidogenesis in the ovary. We demonstrate for the first time how cAMP, PMA and sterol pathways separately and in combination differentially regulate STARD4, STARD6 and STARD1 mRNA levels, as well as STARD1 and STARD4 protein in human primary ovarian cells.


Assuntos
Ovário , Humanos , Feminino , Ovário/metabolismo , Colesterol/metabolismo , Células Cultivadas , RNA Mensageiro/metabolismo , Adulto , Fosfoproteínas/metabolismo , Fosfoproteínas/genética , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Células da Granulosa/metabolismo , Células da Granulosa/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , AMP Cíclico/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas de Membrana Transportadoras
2.
Sci Rep ; 11(1): 656, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436903

RESUMO

Lectins, carbohydrate-binding proteins, have been regarded as potential antiviral agents, as some can bind glycans on viral surface glycoproteins and inactivate their functions. However, clinical development of lectins has been stalled by the mitogenicity of many of these proteins, which is the ability to stimulate deleterious proliferation, especially of immune cells. We previously demonstrated that the mitogenic and antiviral activities of a lectin (banana lectin, BanLec) can be separated via a single amino acid mutation, histidine to threonine at position 84 (H84T), within the third Greek key. The resulting lectin, H84T BanLec, is virtually non-mitogenic but retains antiviral activity. Decreased mitogenicity was associated with disruption of pi-pi stacking between two aromatic amino acids. To examine whether we could provide further proof-of-principle of the ability to separate these two distinct lectin functions, we identified another lectin, Malaysian banana lectin (Malay BanLec), with similar structural features as BanLec, including pi-pi stacking, but with only 63% amino acid identity, and showed that it is both mitogenic and potently antiviral. We then engineered an F84T mutation expected to disrupt pi-pi stacking, analogous to H84T. As predicted, F84T Malay BanLec (F84T) was less mitogenic than wild type. However, F84T maintained strong antiviral activity and inhibited replication of HIV, Ebola, and other viruses. The F84T mutation disrupted pi-pi stacking without disrupting the overall lectin structure. These findings show that pi-pi stacking in the third Greek key is a conserved mitogenic motif in these two jacalin-related lectins BanLec and Malay BanLec, and further highlight the potential to rationally engineer antiviral lectins for therapeutic purposes.


Assuntos
Antivirais/farmacologia , Infecções por HIV/tratamento farmacológico , Lectinas/farmacologia , Leucócitos Mononucleares/efeitos dos fármacos , Mitógenos/farmacologia , Musa/química , Replicação Viral , Proliferação de Células , Células Cultivadas , Ebolavirus/efeitos dos fármacos , Infecções por HIV/virologia , HIV-1/efeitos dos fármacos , Doença pelo Vírus Ebola/tratamento farmacológico , Doença pelo Vírus Ebola/virologia , Humanos , Lectinas/química , Lectinas/genética , Leucócitos Mononucleares/virologia
3.
Proc Natl Acad Sci U S A ; 117(4): 2122-2132, 2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31932446

RESUMO

There is a strong need for a new broad-spectrum antiinfluenza therapeutic, as vaccination and existing treatments are only moderately effective. We previously engineered a lectin, H84T banana lectin (H84T), to retain broad-spectrum activity against multiple influenza strains, including pandemic and avian, while largely eliminating the potentially harmful mitogenicity of the parent compound. The amino acid mutation at position 84 from histidine to threonine minimizes the mitogenicity of the wild-type lectin while maintaining antiinfluenza activity in vitro. We now report that in a lethal mouse model H84T is indeed nonmitogenic, and both early and delayed therapeutic administration of H84T intraperitoneally are highly protective, as is H84T administered subcutaneously. Mechanistically, attachment, which we anticipated to be inhibited by H84T, was only somewhat decreased by the lectin. Instead, H84T is internalized into the late endosomal/lysosomal compartment and inhibits virus-endosome fusion. These studies reveal that H84T is efficacious against influenza virus in vivo, and that the loss of mitogenicity seen previously in tissue culture is also seen in vivo, underscoring the potential utility of H84T as a broad-spectrum antiinfluenza agent.


Assuntos
Antivirais/administração & dosagem , Influenza Humana/tratamento farmacológico , Lectinas/administração & dosagem , Lectinas/genética , Musa/genética , Proteínas de Plantas/administração & dosagem , Proteínas de Plantas/genética , Internalização do Vírus/efeitos dos fármacos , Animais , Humanos , Vírus da Influenza A Subtipo H1N1/efeitos dos fármacos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/fisiologia , Vírus da Influenza A Subtipo H3N2/efeitos dos fármacos , Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/fisiologia , Influenza Humana/virologia , Masculino , Camundongos , Musa/química , Musa/metabolismo , Mutação , Engenharia de Proteínas
4.
PLoS Negl Trop Dis ; 13(7): e0007595, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31356611

RESUMO

Ebolaviruses cause an often rapidly fatal syndrome known as Ebola virus disease (EVD), with average case fatality rates of ~50%. There is no licensed vaccine or treatment for EVD, underscoring the urgent need to develop new anti-ebolavirus agents, especially in the face of an ongoing outbreak in the Democratic Republic of the Congo and the largest ever outbreak in Western Africa in 2013-2016. Lectins have been investigated as potential antiviral agents as they bind glycans present on viral surface glycoproteins, but clinical use of them has been slowed by concerns regarding their mitogenicity, i.e. ability to cause immune cell proliferation. We previously engineered a banana lectin (BanLec), a carbohydrate-binding protein, such that it retained antiviral activity but lost mitogenicity by mutating a single amino acid, yielding H84T BanLec (H84T). H84T shows activity against viruses containing high-mannose N-glycans, including influenza A and B, HIV-1 and -2, and hepatitis C virus. Since ebolavirus surface glycoproteins also contain many high-mannose N-glycans, we assessed whether H84T could inhibit ebolavirus replication. H84T inhibited Ebola virus (EBOV) replication in cell cultures. In cells, H84T inhibited both virus-like particle (VLP) entry and transcription/replication of the EBOV mini-genome at high micromolar concentrations, while inhibiting infection by transcription- and replication-competent VLPs, which measures the full viral life cycle, in the low micromolar range. H84T did not inhibit assembly, budding, or release of VLPs. These findings suggest that H84T may exert its anti-ebolavirus effect(s) by blocking both entry and transcription/replication. In a mouse model, H84T partially (maximally, ~50-80%) protected mice from an otherwise lethal mouse-adapted EBOV infection. Interestingly, a single dose of H84T pre-exposure to EBOV protected ~80% of mice. Thus, H84T shows promise as a new anti-ebolavirus agent with potential to be used in combination with vaccination or other agents in a prophylactic or therapeutic regimen.


Assuntos
Antivirais/farmacologia , Ebolavirus/efeitos dos fármacos , Musa/química , Lectinas de Plantas/farmacologia , Animais , Antivirais/síntese química , Linhagem Celular Tumoral , Ebolavirus/genética , Ebolavirus/imunologia , Escherichia coli , Feminino , Engenharia Genética , Células HEK293 , Doença pelo Vírus Ebola/tratamento farmacológico , Doença pelo Vírus Ebola/prevenção & controle , Humanos , Região Variável de Imunoglobulina/genética , Camundongos , Camundongos Endogâmicos C57BL , Lectinas de Plantas/síntese química , Replicação Viral/efeitos dos fármacos
5.
J Mol Biol ; 428(11): 2275-2288, 2016 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-27075671

RESUMO

A key contributor to HIV-1 genetic variation is reverse transcriptase errors. Some mutations result because reverse transcriptase (RT) lacks 3' to 5' proofreading exonuclease and can extend mismatches. However, RT also excises terminal nucleotides to a limited extent, and this activity contributes to AZT resistance. Because HIV-1 mismatch resolution has been studied in vitro but only indirectly during replication, we developed a novel system to study mismatched base pair resolution during HIV-1 replication in cultured cells using vectors that force template switching at defined locations. These vectors generated mismatched reverse transcription intermediates, with proviral products diagnostic of mismatch resolution mechanisms. Outcomes for wild-type (WT) RT and an AZT-resistant (AZT(R)) RT containing a thymidine analog mutation set-D67N, K70R, D215F, and K219Q-were compared. AZT(R) RT did not excise terminal nucleotides more frequently than WT, and for the majority of tested mismatches, both WT and AZT(R) RTs extended mismatches in more than 90% of proviruses. However, striking enzyme-specific differences were observed for one mispair, with WT RT preferentially resolving dC-rC pairs either by excising the mismatched base or switching templates prematurely, while AZT(R) RT primarily misaligned the primer strand, causing deletions via dislocation mutagenesis. Overall, the results confirmed HIV-1 RT's high capacity for mismatch extension during virus replication and revealed dramatic differences in aberrant intermediate resolution repertoires between WT and AZT(R) RTs on one mismatched replication intermediate. Correlating mismatch extension frequencies observed here with reported viral mutation rates suggests a complex interplay of nucleotide discrimination and mismatch extension drives HIV-1 mutagenesis.


Assuntos
Reparo de Erro de Pareamento de DNA/genética , DNA Viral/genética , Farmacorresistência Viral/genética , Transcriptase Reversa do HIV/metabolismo , HIV-1/genética , Nucleotídeos/genética , Replicação Viral/genética , Fármacos Anti-HIV/farmacologia , Reparo de Erro de Pareamento de DNA/efeitos dos fármacos , Primers do DNA/genética , Replicação do DNA/efeitos dos fármacos , Replicação do DNA/genética , HIV-1/efeitos dos fármacos , Humanos , Mutação/efeitos dos fármacos , Mutação/genética , Inibidores da Transcriptase Reversa/farmacologia , Moldes Genéticos , Replicação Viral/efeitos dos fármacos
6.
ACS Cent Sci ; 2(12): 943-953, 2016 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-28058284

RESUMO

Nonlamellar lipid arrangements, including cubosomes, appear in unhealthy cells, e.g., when they are subject to stress, starvation, or viral infection. The bioactivity of cubosomes-nanoscale particles exhibiting bicontinuous cubic structures-versus more common vesicles is an unexplored area due to lack of suitable model systems. Here, glycodendrimercubosomes (GDCs)-sugar-presenting cubosomes assembled from Janus glycodendrimers by simple injection into buffer-are proposed as mimics of biological cubic membranes. The bicontinuous cubic GDC architecture has been demonstrated by electron tomography. The stability of these GDCs in buffer enabled studies on lectin-dependent agglutination, revealing significant differences compared with the vesicular glycodendrimersome (GDS) counterpart. In particular, GDCs showed an increased activity toward concanavalin A, as well as an increased sensitivity and selectivity toward two variants of banana lectins, a wild-type and a genetically modified variant, which is not exhibited by GDSs. These results suggest that cells may adapt under unhealthy conditions by undergoing a transformation from lamellar to cubic membranes as a method of defense.

7.
J Virol ; 88(17): 9673-82, 2014 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-24920813

RESUMO

UNLABELLED: Human endogenous retrovirus type K (HERV-K) proviruses are scattered throughout the human genome, but as no infectious HERV-K virus has been detected to date, the mechanism by which these viruses replicated and populated the genome remains unresolved. Here, we provide evidence that, in addition to the RNA genomes that canonical retroviruses package, modern HERV-K viruses can contain reverse-transcribed DNA (RT-DNA) genomes. Indeed, reverse transcription of genomic HERV-K RNA into the DNA form is able to occur in three distinct times and locations: (i) in the virus-producing cell prior to viral release, yielding a DNA-containing extracellular virus particle similar to the spumaviruses; (ii) within the extracellular virus particle itself, transitioning from an RNA-containing particle to a DNA-containing particle; and (iii) after entry of the RNA-containing virus into the target cell, similar to canonical retroviruses, such as murine leukemia virus and HIV. Moreover, using a resuscitated HERV-K virus construct, we show that both viruses with RNA genomes and viruses with DNA genomes are capable of infecting target cells. This high level of genomic flexibility historically could have permitted these viruses to replicate in various host cell environments, potentially assisting in their many integration events and resulting in their high prevalence in the human genome. Moreover, the ability of modern HERV-K viruses to proceed through reverse transcription and package RT-DNA genomes suggests a higher level of replication competency than was previously understood, and it may be relevant in HERV-K-associated human diseases. IMPORTANCE: Retroviral elements comprise at least 8% of the human genome. Of all the endogenous retroviruses, HERV-K viruses are the most intact and biologically active. While a modern infectious HERV-K has yet to be found, HERV-K activation has been associated with cancers, autoimmune diseases, and HIV-1 infection. Thus, determining how this virus family became such a prevalent member of our genome and what it is capable of in its current form are of the utmost importance. Here, we provide evidence that HERV-K viruses currently found in the human genome are able to proceed through reverse transcription and historically utilized a life cycle with a surprising degree of genomic flexibility in which both RNA- and DNA-containing viruses were capable of mediating infection.


Assuntos
DNA Viral/genética , DNA Viral/metabolismo , Retrovirus Endógenos/genética , Genoma Viral , Provírus/genética , Linhagem Celular Tumoral , Retrovirus Endógenos/fisiologia , Humanos , RNA Viral/genética , RNA Viral/metabolismo , Transcrição Reversa , Montagem de Vírus
8.
Exp Biol Med (Maywood) ; 239(4): 430-5, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24595982

RESUMO

STARD6 is a member of the StAR-related lipid transfer (START) domain family of proteins whose function thus far remains obscure. While it recently was shown to facilitate steroidogenesis in a cell-free setting, it has not been localized to steroidogenic cells of normal reproductive tissues. In a recent microarray study, we detected STARD6 mRNA in cultured porcine ovarian granulosa cells which are steroidogenic. In the present study, we examined regulation of STARD6 mRNA in porcine granulosa cultures, and found that it was not regulated by cyclic AMP, but it was reduced by combined knockdown of the transcription factors GATA4 and GATA6. We detected both STARD6 mRNA and protein in fresh granulosa cells and whole antral follicles and different stage corpora lutea of pig. The highest levels were discovered in the mid-luteal phase corpus luteum. Immunolocalization within ovarian tissues indicated robust STARD6 immunoreactivity in steroidogenic cells of the corpus luteum. Relatively lesser amounts of STARD6 signal were found in granulosa cells, theca cells, and oocytes. To test the ability of STARD6 to facilitate de novo steroidogenesis, non-steroidogenic COS-1 cells were co-transfected with components of the P450 cholesterol side-chain cleavage system, enabling them to make pregnenolone, and STARD6. STARD6 increased pregnenolone production by two- to three-fold over the empty vector control. In summary, STARD6 is found in the pig ovary, exhibits the strongest expression in highly steroidogenic luteal cells, and significantly enhances pregnenolone production in transfected COS cells independent of cyclic AMP treatment. Collectively, these findings indicate that STARD6 may contribute to steroidogenesis in ovarian cells, but also suggests other cellular functions that require cholesterol trafficking.


Assuntos
Proteínas de Membrana Transportadoras/fisiologia , Ovário/metabolismo , Suínos/metabolismo , Animais , Células COS , Chlorocebus aethiops , Corpo Lúteo/metabolismo , AMP Cíclico/metabolismo , Ciclo Estral/metabolismo , Feminino , Fator de Transcrição GATA4/genética , Fator de Transcrição GATA6/genética , Técnicas de Silenciamento de Genes , Células da Granulosa/metabolismo , Imuno-Histoquímica , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Folículo Ovariano/metabolismo , Interferência de RNA , RNA Mensageiro
9.
Endocrinology ; 155(2): 576-91, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24265455

RESUMO

Both retinoic acid receptors (RARs) and retinoid X receptors (RXRs) mediate the action of retinoids that play important roles in reproductive development and function, as well as steroidogenesis. Regulation of steroid biosynthesis is principally mediated by the steroidogenic acute regulatory protein (StAR); however, the modes of action of retinoids in the regulation of steroidogenesis remain obscure. In this study we demonstrate that all-trans retinoic acid (atRA) enhances StAR expression, but not its phosphorylation (P-StAR), and progesterone production in MA-10 mouse Leydig cells. Activation of the protein kinase A (PKA) cascade, by dibutyrl-cAMP or type I/II PKA analogs, markedly increased retinoid-responsive StAR, P-StAR, and steroid levels. Targeted silencing of endogenous RARα and RXRα, with small interfering RNAs, resulted in decreases in 9-cis RA-stimulated StAR and progesterone levels. Truncation of and mutational alterations in the 5'-flanking region of the StAR gene demonstrated the importance of the -254/-1-bp region in retinoid responsiveness. An oligonucleotide probe encompassing an RXR/liver X receptor recognition motif, located within the -254/-1-bp region, specifically bound MA-10 nuclear proteins and in vitro transcribed/translated RXRα and RARα in EMSAs. Transcription of the StAR gene in response to atRA and dibutyrl-cAMP was influenced by several factors, its up-regulation being dependent on phosphorylation of cAMP response-element binding protein (CREB). Chromatin immunoprecipitation studies revealed the association of phosphorylation of CREB, CREB binding protein, RXRα, and RARα to the StAR promoter. Further studies elucidated that hormone-sensitive lipase plays an important role in atRA-mediated regulation of the steroidogenic response that involves liver X receptor signaling. These findings delineate the molecular events by which retinoids influence cAMP/PKA signaling and provide additional and novel insight into the regulation of StAR expression and steroidogenesis in mouse Leydig cells.


Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , AMP Cíclico/metabolismo , Fosfoproteínas/metabolismo , Retinoides/metabolismo , Esteroides/biossíntese , Animais , Bucladesina/farmacologia , AMP Cíclico/genética , Proteínas Quinases Dependentes de AMP Cíclico/genética , Células Intersticiais do Testículo/citologia , Células Intersticiais do Testículo/efeitos dos fármacos , Células Intersticiais do Testículo/metabolismo , Masculino , Camundongos , Fosfoproteínas/genética , Fosforilação , Regiões Promotoras Genéticas/efeitos dos fármacos , Receptores do Ácido Retinoico/genética , Receptores do Ácido Retinoico/metabolismo , Receptores X de Retinoides/genética , Receptores X de Retinoides/metabolismo , Retinoides/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/fisiologia
10.
Front Oncol ; 3: 31, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23508883

RESUMO

The National Cancer Institute clinical cooperative groups have been instrumental over the past 50 years in developing clinical trials and evidence-based process improvements for clinical oncology patient care. The cooperative groups are undergoing a transformation process as we further integrate molecular biology into personalized patient care and move to incorporate international partners in clinical trials. To support this vision, data acquisition and data management informatics tools must become both nimble and robust to support transformational research at an enterprise level. Information, including imaging, pathology, molecular biology, radiation oncology, surgery, systemic therapy, and patient outcome data needs to be integrated into the clinical trial charter using adaptive clinical trial mechanisms for design of the trial. This information needs to be made available to investigators using digital processes for real-time data analysis. Future clinical trials will need to be designed and completed in a timely manner facilitated by nimble informatics processes for data management. This paper discusses both past experience and future vision for clinical trials as we move to develop data management and quality assurance processes to meet the needs of the modern trial.

11.
J Virol ; 86(15): 7790-805, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22593154

RESUMO

Human endogenous retroviruses (HERVs) make up 8% of the human genome. The expression of HERV-K (HML-2), the family of HERVs that most recently entered the genome, is tightly regulated but becomes markedly increased after infection with HIV-1. To better understand the mechanisms involved in this activation, we explored the role of the HIV-1 Tat protein in inducing the expression of these endogenous retroviral genes. Administration of recombinant HIV-1 Tat protein caused a 13-fold increase in HERV-K (HML-2) gag RNA transcripts in Jurkat T cells and a 10-fold increase in primary lymphocytes, and the expression of the HERV-K (HML-2) rec and np9 oncogenes was also markedly increased. This activation was seen especially in lymphocytes and monocytic cells, the natural hosts for HIV-1 infection. Luciferase reporter gene assays demonstrated that the effect of Tat on HERV-K (HML-2) expression occurred at the level of the transcriptional promoter. The transcription factors NF-κB and NF-AT contribute to the Tat-induced activation of the promoter, as shown by chromatin immunoprecipitation assays, mutational analysis of the HERV-K (HML-2) long terminal repeat, and treatments with agents that inhibit NF-κB or NF-AT activation. These studies demonstrate that HIV-1 Tat plays an important role in activating expression of HERV-K (HML-2) in the setting of HIV-1 infection.


Assuntos
Retrovirus Endógenos/fisiologia , Regulação Viral da Expressão Gênica , Produtos do Gene env/biossíntese , Infecções por HIV/metabolismo , HIV-1/metabolismo , Proteínas do Envelope Viral/biossíntese , Ativação Viral , Produtos do Gene tat do Vírus da Imunodeficiência Humana/metabolismo , Produtos do Gene env/genética , Infecções por HIV/genética , HIV-1/genética , Humanos , Células Jurkat , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia , Proteínas do Envelope Viral/genética , Produtos do Gene tat do Vírus da Imunodeficiência Humana/genética , Produtos do Gene tat do Vírus da Imunodeficiência Humana/farmacologia
12.
Front Biosci (Landmark Ed) ; 17(3): 824-46, 2012 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-22201776

RESUMO

The steroidogenic acute regulatory protein, cytochrome P450 cholesterol side-chain cleavage enzyme and specific 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerases initiate the essential process of steroidogenesis in the gonads. Testicular and ovarian expression of their respective genes, STARD1, CYP11A1 and gonadal HSD3B, is primarily controlled by gonadotropins with contributions by various growth factors. Gonadotropins through their receptors switch on cyclic AMP signaling pathways that recruit NR5A, GATA and often CREB, NR4A, or Sp1 transcription factors to regulatory regions of each gene's promoter to elicit transcription. The specific combination of transcription factors involved depends on the cellular context. In this review, we summarize current understanding of the factors that control transactivation of the STARD1, CYP11A1 and gonadal HSD3B genes in Leydig cells in the testis and the theca, differentiating granulosa and luteal cells in the ovary.


Assuntos
Enzima de Clivagem da Cadeia Lateral do Colesterol/genética , Complexos Multienzimáticos/genética , Ovário/metabolismo , Fosfoproteínas/genética , Progesterona Redutase/genética , Esteroide Isomerases/genética , Testículo/metabolismo , Animais , Feminino , Células da Granulosa/metabolismo , Humanos , Células Intersticiais do Testículo/metabolismo , Células Lúteas/metabolismo , Masculino , Esteroides/biossíntese , Ativação Transcricional
13.
Artigo em Inglês | MEDLINE | ID: mdl-22649383

RESUMO

Locally produced neurosteroids are proposed to have many functions in the central nervous system. The identification of the steroidogenic acute regulatory protein in steroid-producing neural cells provides a new tool to understand the sites, regulation, and importance of their synthesis.

14.
Endocr Dev ; 20: 47-53, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21164258

RESUMO

The steroidogenic acute regulatory (StAR) protein is essential for all hormone-stimulated steroid biosynthesis. Accordingly, its absence gives rise to the most severe form of congenital adrenal hyperplasia (CAH), lipoid CAH. This life-threatening condition typically manifests itself in the perinatal period. Partial loss-of-function StAR mutations incompletely manifest the condition later in life and are a cause of familial glucocorticoid deficiency type 3. Here, we discuss StAR, its expression pattern and the clinical consequences of the loss of its activity.


Assuntos
Fosfoproteínas/genética , Fosfoproteínas/fisiologia , Hiperplasia Suprarrenal Congênita/genética , Hiperplasia Suprarrenal Congênita/fisiopatologia , Animais , Transtorno 46,XY do Desenvolvimento Sexual/genética , Transtorno 46,XY do Desenvolvimento Sexual/fisiopatologia , Perfilação da Expressão Gênica , Humanos , Mutação/fisiologia
15.
J Virol ; 84(18): 9070-7, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20610725

RESUMO

HIV-1 is known to package several small cellular RNAs in addition to its genome. Previous work consistently demonstrated that the host structural RNA 7SL is abundant in HIV-1 virions but has yielded conflicting results regarding whether 7SL is present in minimal, assembly-competent virus-like particles (VLPs). Here, we demonstrate that minimal HIV-1 VLPs retain 7SL RNA primarily as an endoribonucleolytic fragment, referred to as 7SL remnant (7SLrem). Nuclease mapping showed that 7SLrem is a 111-nucleotide internal portion of 7SL, with 5' and 3' ends corresponding to unpaired loops in the 7SL two-dimensional structure. Analysis of VLPs comprised of different subsets of Gag domains revealed that all NC-positive VLPs contained intact 7SL while the presence of 7SLrem correlated with the absence of the NC domain. Because 7SLrem, which maps to the 7SL S domain, was not detectable in infected cells, we propose a model whereby the species recruited to assembling VLPs is intact 7SL RNA, with 7SLrem produced by an endoribonuclease in the absence of NC. Since recruitment of 7SL RNA was a conserved feature of all tested minimal VLPs, our model further suggests that 7SL's recruitment is mediated, either directly or indirectly, through interactions with conserved features of all tested VLPs, such as the C-terminal domain of CA.


Assuntos
HIV-1/química , RNA Citoplasmático Pequeno/análise , Partícula de Reconhecimento de Sinal/análise , Vírion/química , Virossomos/química , Sequência de Bases , Linhagem Celular , Humanos , Modelos Biológicos , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Ribonucleases/metabolismo
16.
J Mol Biol ; 396(1): 141-52, 2010 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-19931283

RESUMO

Retroviruses selectively package two copies of their RNA genomes via mechanisms that have yet to be fully deciphered. Recent studies with small fragments of the Moloney murine leukemia virus (MoMuLV) genome suggested that selection may be mediated by an RNA switch mechanism, in which conserved UCUG elements that are sequestered by base-pairing in the monomeric RNA become exposed upon dimerization to allow binding to the cognate nucleocapsid (NC) domains of the viral Gag proteins. Here we show that a large fragment of the MoMuLV 5' untranslated region that contains all residues necessary for efficient RNA packaging (Psi(WT); residues 147-623) also exhibits a dimerization-dependent affinity for NC, with the native dimer ([Psi(WT)](2)) binding 12+/-2 NC molecules with high affinity (K(d)=17+/-7 nM) and with the monomer, stabilized by substitution of dimer-promoting loop residues with hairpin-stabilizing sequences (Psi(M)), binding 1-2 NC molecules. Identical dimer-inhibiting mutations in MoMuLV-based vectors significantly inhibit genome packaging in vivo (approximately 100-fold decrease), whereas a large deletion of nearly 200 nucleotides just upstream of the gag start codon has minimal effects. Our findings support the proposed RNA switch mechanism and further suggest that virus assembly may be initiated by a complex comprising as few as 12 Gag molecules bound to a dimeric packaging signal.


Assuntos
Diploide , Genoma Viral/genética , Vírus da Leucemia Murina de Moloney/genética , Vírus da Leucemia Murina de Moloney/fisiologia , RNA Viral/química , RNA Viral/genética , Montagem de Vírus/genética , Sequência de Bases , Sítios de Ligação , Linhagem Celular , Dimerização , Humanos , Dados de Sequência Molecular , Mutação/genética , Conformação de Ácido Nucleico , Nucleocapsídeo/genética , Estabilidade de RNA , Temperatura , Transcrição Gênica
17.
J Virol ; 83(23): 12526-34, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19776129

RESUMO

Moloney murine leukemia virus (MLV) selectively encapsidates host mY1 and mY3 RNAs. These noncoding RNA polymerase III transcripts are normally complexed with the Ro60 and La proteins, which are autoantigens associated with rheumatic disease that function in RNA biogenesis and quality control. Here, MLV replication and mY RNA packaging were analyzed using Ro60 knockout embryonic fibroblasts, which contain only approximately 3% as much mY RNA as wild-type cells. Virus spread at the same rate in wild-type and Ro knockout cells. Surprisingly, MLV virions shed by Ro60 knockout cells continued to package high levels of mY1 and mY3 (about two copies of each) like those from wild-type cells, even though mY RNAs were barely detectable within producer cells. As a result, for MLV produced in Ro60 knockout cells, encapsidation selectivity from among all cell RNAs was even higher for mY RNAs than for the viral genome. Whereas mY RNAs are largely cytoplasmic in wild-type cells, fractionation of knockout cells revealed that the residual mY RNAs were relatively abundant in nuclei, likely reflecting the fact that most mY RNAs were degraded shortly after transcription in the absence of Ro60. Together, these data suggest that these small, labile host RNAs may be recruited at a very early stage of their biogenesis and may indicate an intersection of retroviral assembly and RNA quality control pathways.


Assuntos
Vírus da Leucemia Murina de Moloney/fisiologia , RNA Citoplasmático Pequeno/metabolismo , Montagem de Vírus , Animais , Autoantígenos , Linhagem Celular , Fibroblastos/virologia , Camundongos , Camundongos Knockout , Ribonucleoproteínas/deficiência
18.
Exp Biol Med (Maywood) ; 234(8): 880-907, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19491374

RESUMO

Expression of the genes that mediate the first steps in steroidogenesis, the steroidogenic acute regulatory protein (STARD1), the cholesterol side-chain cleavage enzyme, cytochrome P450scc (CYP11A1) and 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase (HSD3B), is tightly controlled by a battery of transcription factors in the adrenal cortex, the gonads and the placenta. These genes generally respond to the same hormones that stimulate steroid production through common pathways such as cAMP signaling and common actions on their promoters by proteins such as NR5A and GATA family members. However, there are distinct temporal, tissue and species-specific differences in expression between the genes that are defined by combinatorial regulation and unique promoter elements. This review will provide an overview of the hormonal and transcriptional regulation of the STARD1, CYP11A1 and specific steroidogenic HSD3B genes in the adrenal, testis, ovary and placenta and discuss the current knowledge regarding the key transcriptional factors involved.


Assuntos
Enzima de Clivagem da Cadeia Lateral do Colesterol/genética , Regulação da Expressão Gênica , Fosfoproteínas/genética , Progesterona Redutase/genética , Transcrição Gênica , Animais , Sequência de Bases , Enzima de Clivagem da Cadeia Lateral do Colesterol/metabolismo , Humanos , Dados de Sequência Molecular , Especificidade de Órgãos/genética , Fosfoproteínas/metabolismo , Progesterona Redutase/metabolismo
19.
J Androl ; 29(5): 524-33, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18567641

RESUMO

Although gonadal and adrenal steroids heavily impact sexual function at the level of the brain, the nervous system also produces its own steroids de novo that may regulate sexual behavior and reproduction. Current evidence points to important roles for neurosteroids in sexual and gender-typical behaviors, control of ovulation, and behaviors that strongly influence sexual interest and motivation like aggression, anxiety and depression. At the cellular level, neurosteroids act through stimulating rapid changes in excitability and direct activation of membrane receptors in neurons. Thus, unlike peripheral steroids, neurosteroids can have immediate and specific effects on select neuronal pathways to regulate sexual function.


Assuntos
Fenômenos Fisiológicos do Sistema Nervoso , Comportamento Sexual/fisiologia , Esteroides/fisiologia , Animais , Ansiedade/etiologia , Química Encefálica , Depressão/etiologia , Feminino , Humanos , Masculino , Receptores de Superfície Celular/fisiologia , Reprodução/fisiologia , Sexo , Caracteres Sexuais
20.
J Ethnopharmacol ; 118(1): 159-65, 2008 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-18495396

RESUMO

In the mountains of Peru, globular colonies of Nostoc commune (Nostocales) are collected in the highland lakes by the indigenous people, who call them llullucha. They are consumed locally, traded for maize, or sold, eventually entering the folk markets of Cusco and other neighboring cities. Throughout highland Peru, Nostoc commune is highly salient as a seasonal dietary item, being eaten alone, or in picante -- a local stew -- and is said to be highly nutritious. Nostoc commune has been known to produce unusual amino acids, including those of the mycosporine group, which possibly function to prevent UV damage. We analyzed 21 different Nostoc commune spherical colonies from 7 different market collections in the Cusco area for the presence of beta-N-methylamino-L-alanine (BMAA), a neurotoxic amino acid produced by diverse taxa of cyanobacteria, using four different analytical techniques (HPLC-FD, UPLC-UV, UPLC/MS, LC/MS/MS). We found using all four techniques that BMAA was present in the samples purchased in the Peruvian markets. Since BMAA has been putatively linked to neurodegenerative illness, it would be of interest to know if the occurrence of ALS, Alzheimer's, or Parkinson's Disease is greater among individuals who consume llullucha in Peru.


Assuntos
Diamino Aminoácidos/metabolismo , Neurotoxinas/metabolismo , Nostoc commune/química , Diamino Aminoácidos/análise , Diamino Aminoácidos/toxicidade , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida/métodos , Toxinas de Cianobactérias , Suplementos Nutricionais , Medicina Tradicional , Neurotoxinas/análise , Neurotoxinas/toxicidade , Peru , Espectrometria de Massas em Tandem/métodos
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