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Hensen SMM, Heldens L, van Genesen ST, Pruijn GJM, Lubsen NH. A delayed antioxidant response in heat-stressed cells expressing a non-DNA binding HSF1 mutant. Cell Stress Chaperones 2013; 18:455-73. [PMID: 23321918 PMCID: PMC3682012 DOI: 10.1007/s12192-012-0400-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 12/20/2012] [Accepted: 12/21/2012] [Indexed: 12/30/2022] Open
Abstract
To assess the consequences of inactivation of heat shock factor 1 (HSF1) during aging, we analyzed the effect of HSF1 K80Q, a mutant unable to bind DNA, and of dnHSF1, a mutant lacking the activation domain, on the transcriptome of cells 6 and 24 h after heat shock. The primary response to heat shock (6 h recovery), of which 30 % was HSF1-dependent, had decayed 24 h after heat shock in control cells but was extended in HSF1 K80Q and dnHSF1 cells. Comparison with literature data showed that even the HSF1 dependent primary stress response is largely cell specific. HSF1 K80Q, but not HSF1 siRNA-treated, cells showed a delayed stress response: an increase in transcript levels of HSF1 target genes 24 h after heat stress. Knockdown of NRF2, but not of ATF4, c-Fos or FosB, inhibited this delayed stress response. EEF1D_L siRNA inhibited both the delayed and the extended primary stress responses, but had off target effects. In control cells an antioxidant response (ARE binding, HMOX1 mRNA levels) was detected 6 h after heat shock; in HSF1 K80Q cells this response was delayed to 24 h and the ARE complex had a different mobility. Inactivation of HSF1 thus affects the timing and nature of the antioxidant response and NRF2 can activate at least some HSF1 target genes in the absence of HSF1 activity.
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Affiliation(s)
- Sanne M. M. Hensen
- 271 Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Lonneke Heldens
- 271 Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Siebe T. van Genesen
- 271 Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Ger J. M. Pruijn
- 271 Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Nicolette H. Lubsen
- 271 Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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Hensen SMM, Heldens L, van Enckevort CMW, van Genesen ST, Pruijn GJM, Lubsen NH. Activation of the antioxidant response in methionine deprived human cells results in an HSF1-independent increase in HSPA1A mRNA levels. Biochimie 2013; 95:1245-51. [PMID: 23395854 DOI: 10.1016/j.biochi.2013.01.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 01/29/2013] [Indexed: 12/30/2022]
Abstract
In cells starved for leucine, lysine or glutamine heat shock factor 1 (HSF1) is inactivated and the level of the transcripts of the HSF1 target genes HSPA1A (Hsp70) and DNAJB1 (Hsp40) drops. We show here that in HEK293 cells deprived of methionine HSF1 was similarly inactivated but that the level of HSPA1A and DNAJB1 mRNA increased. This increase was also seen in cells expressing a dominant negative HSF1 mutant (HSF379 or HSF1-K80Q), confirming that the increase is HSF1 independent. The antioxidant N-acetylcysteine completely inhibited the increase in HSPA1A and DNAJB1 mRNA levels upon methionine starvation, indicating that this increase is a response to oxidative stress resulting from a lack of methionine. Cells starved for methionine contained higher levels of c-Fos and FosB mRNA, but knockdown of these transcription factors had no effect on the HSPA1A or DNAJB1 mRNA level. Knockdown of NRF2 mRNA resulted in the inhibition of the increase in the HSPA1A mRNA, but not the DNAJB1 mRNA, level in methionine starved cells. We conclude that methionine deprivation results in both the amino acid deprivation response and an antioxidant response mediated at least in part by NRF2. This antioxidant response includes an HSF1 independent increase in the levels of HSPA1A and DNAJB1 mRNA.
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Affiliation(s)
- Sanne M M Hensen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, NL-6500 HB Nijmegen, The Netherlands
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Hensen SMM, Heldens L, van Enckevort CMW, van Genesen ST, Pruijn GJM, Lubsen NH. Heat shock factor 1 is inactivated by amino acid deprivation. Cell Stress Chaperones 2012; 17:743-55. [PMID: 22797943 PMCID: PMC3468675 DOI: 10.1007/s12192-012-0347-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 06/18/2012] [Accepted: 06/20/2012] [Indexed: 11/14/2022] Open
Abstract
Mammalian cells respond to a lack of amino acids by activating a transcriptional program with the transcription factor ATF4 as one of the main actors. When cells are faced with cytoplasmic proteotoxic stress, a quite different transcriptional response is mounted, the heat shock response, which is mediated by HSF1. Here, we show that amino acid deprivation results in the inactivation of HSF1. In amino acid deprived cells, active HSF1 loses its DNA binding activity as demonstrated by EMSA and ChIP. A sharp decrease in the transcript level of HSF1 target genes such as HSPA1A (Hsp70), DNAJB1 (Hsp40), and HSP90AA1 is also seen. HSPA1A mRNA, but not DNAJB1 mRNA, was also destabilized. In cells cultured with limiting leucine, HSF1 activity also declined. Lack of amino acids thus could lead to a lower chaperoning capacity and cellular frailty. We show that the nutrient sensing response unit of the ASNS gene contains an HSF1 binding site, but we could not detect binding of HSF1 to this site in vivo. Expression of either an HSF1 mutant lacking the activation domain (HSF379) or an HSF1 mutant unable to bind DNA (K80Q) had only a minor effect on the transcript levels of amino acid deprivation responsive genes.
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Affiliation(s)
- Sanne M. M. Hensen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Lonneke Heldens
- Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Chrissy M. W. van Enckevort
- Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Siebe T. van Genesen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Ger J. M. Pruijn
- Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Nicolette H. Lubsen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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Clark AR, Lubsen NH, Slingsby C. sHSP in the eye lens: Crystallin mutations, cataract and proteostasis. Int J Biochem Cell Biol 2012; 44:1687-97. [DOI: 10.1016/j.biocel.2012.02.015] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 02/23/2012] [Indexed: 01/25/2023]
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Heldens L, van Genesen ST, Hanssen LLP, Hageman J, Kampinga HH, Lubsen NH. Protein refolding in peroxisomes is dependent upon an HSF1-regulated function. Cell Stress Chaperones 2012; 17:603-13. [PMID: 22477622 PMCID: PMC3535170 DOI: 10.1007/s12192-012-0335-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 03/11/2012] [Accepted: 03/12/2012] [Indexed: 12/22/2022] Open
Abstract
Post-heat shock refolding of luciferase requires chaperones. Expression of a dominant negative HSF1 mutant (dnHSF1), which among other effects depletes cells of HSF1-regulated chaperones, blocked post-heat shock refolding of luciferase targeted to the cytoplasm, nucleus, or peroxisomes, while refolding of endoplasmic reticulum (ER)-targeted luciferase was inhibited by about 50 %. Luciferase refolding in the cytoplasm could be partially restored by expression of HSPA1A and fully by both HSPA1A and DNAJB1. For full refolding of ER luciferase, HSPA1A expression sufficed. Neither nuclear nor peroxisomal refolding was rescued by HSPA1A. A stimulatory effect of DNAJB1 on post-heat shock peroxisomal luciferase refolding was seen in control cells, while refolding in the cytoplasm or nucleus in control cells was inhibited by DNAJB1 expression in the absence of added HSPA1A. HSPB1 also improved refolding of peroxisomal luciferase in control cells, but not in dnHSF1 expressing cells. HSP90, HSPA5, HSPA6, and phosphomevalonate kinase (of which the synthesis is also downregulated by dnHSF1) had no effect on peroxisomal refolding in either control or chaperone-depleted cells. The chaperone requirement for post-heat shock refolding of peroxisomal luciferase in control cells is thus unusual in that it can be augmented by DNAJB1 or HSPB1 but not by HSPA1A; in dnHSF1 expressing cells, expression of none of the (co)-chaperones tested was effective, and an as yet to be identified, HSF1-regulated function is required.
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Affiliation(s)
- Lonneke Heldens
- 271 Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Siebe T. van Genesen
- 271 Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Lars L. P. Hanssen
- 271 Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Jurre Hageman
- Section of Radiation and Stress Cell Biology, Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, 9700 AD The Netherlands
| | - Harm H. Kampinga
- Section of Radiation and Stress Cell Biology, Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, 9700 AD The Netherlands
| | - Nicolette H. Lubsen
- 271 Department of Biomolecular Chemistry, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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Heldens L, Hensen SMM, Onnekink C, van Genesen ST, Dirks RP, Lubsen NH. An atypical unfolded protein response in heat shocked cells. PLoS One 2011; 6:e23512. [PMID: 21853144 PMCID: PMC3154502 DOI: 10.1371/journal.pone.0023512] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Accepted: 07/19/2011] [Indexed: 11/18/2022] Open
Abstract
Background The heat shock response (HSR) and the unfolded protein response (UPR) are both activated by proteotoxic stress, although in different compartments, and share cellular resources. How these resources are allocated when both responses are active is not known. Insight in possible crosstalk will help understanding the consequences of failure of these systems in (age-related) disease. Results In heat stressed HEK293 cells synthesis of the canonical UPR transcription factors XBP1s and ATF4 was detected as well as HSF1 independent activation of the promoters of the ER resident chaperones HSPA5 (BiP) and DNAJB9 (ERdj4). However, the heat stress activation of the DNAJB9 promoter, a XBP1s target, was not blocked in cells expressing a dominant negative IRE1α mutant, and thus did not require XBP1s. Furthermore, the DNA element required for heat stress activation of the DNAJB9 promoter is distinct from the ATF4 and ATF6 target elements; even though inhibition of eIF2α phosphorylation resulted in a decreased activation of the DNAJB9 promoter upon heat stress, suggesting a role for an eIF2α phosphorylation dependent product. Conclusions The initial step in the UPR, synthesis of transcription factors, is activated by heat stress but the second step, transcriptional transactivation by these factors, is blocked and these pathways of the UPR are thus not productive. Expression of canonical ER chaperones is part of the response of heat stressed cells but another set of transcription factors has been recruited to regulate expression of these ER chaperones.
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Affiliation(s)
- Lonneke Heldens
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Sanne M. M. Hensen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Carla Onnekink
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Siebe T. van Genesen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Ron P. Dirks
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Nicolette H. Lubsen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
- * E-mail:
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Kappé G, Purkiss AG, van Genesen ST, Slingsby C, Lubsen NH. Erratum to: Explosive Expansion of βγ-Crystallin Genes in the Ancestral Vertebrate. J Mol Evol 2010. [PMCID: PMC3462978 DOI: 10.1007/s00239-010-9387-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Guido Kappé
- Biomolecular Chemistry 271, NCMLS, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Andrew G. Purkiss
- Department of Biological Sciences, Crystallography, Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London, WC1E 7HX UK
| | - Siebe T. van Genesen
- Biomolecular Chemistry 271, NCMLS, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Christine Slingsby
- Department of Biological Sciences, Crystallography, Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London, WC1E 7HX UK
| | - Nicolette H. Lubsen
- Biomolecular Chemistry 271, NCMLS, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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Heldens L, Dirks RP, Hensen SMM, Onnekink C, van Genesen ST, Rustenburg F, Lubsen NH. Co-chaperones are limiting in a depleted chaperone network. Cell Mol Life Sci 2010; 67:4035-48. [PMID: 20556630 PMCID: PMC2981734 DOI: 10.1007/s00018-010-0430-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Revised: 04/29/2010] [Accepted: 05/26/2010] [Indexed: 11/26/2022]
Abstract
To probe the limiting nodes in the chaperoning network which maintains cellular proteostasis, we expressed a dominant negative mutant of heat shock factor 1 (dnHSF1), the regulator of the cytoplasmic proteotoxic stress response. Microarray analysis of non-stressed dnHSF1 cells showed a two- or more fold decrease in the transcript level of 10 genes, amongst which are the (co-)chaperone genes HSP90AA1, HSPA6, DNAJB1 and HSPB1. Glucocorticoid signaling, which requires the Hsp70 and the Hsp90 folding machines, was severely impaired by dnHSF1, but fully rescued by expression of DNAJA1 or DNAJB1, and partially by ST13. Expression of DNAJB6, DNAJB8, HSPA1A, HSPB1, HSPB8, or STIP1 had no effect while HSP90AA1 even inhibited. PTGES3 (p23) inhibited only in control cells. Our results suggest that the DNAJ co-chaperones in particular become limiting in a depleted chaperoning network. Our results also suggest a difference between the transcriptomes of cells lacking HSF1 and cells expressing dnHSF1.
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Affiliation(s)
- Lonneke Heldens
- Department of Biomolecular Chemistry 271, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Ron P. Dirks
- Department of Biomolecular Chemistry 271, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Sanne M. M. Hensen
- Department of Biomolecular Chemistry 271, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Carla Onnekink
- Department of Biomolecular Chemistry 271, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Siebe T. van Genesen
- Department of Biomolecular Chemistry 271, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
| | - François Rustenburg
- Section Micro Array Facility, Department of Pathology, VU University Medical Center, Amsterdam, The Netherlands
| | - Nicolette H. Lubsen
- Department of Biomolecular Chemistry 271, Radboud University Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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Dirks RP, van Geel R, Hensen SMM, van Genesen ST, Lubsen NH. Manipulating heat shock factor-1 in Xenopus tadpoles: neuronal tissues are refractory to exogenous expression. PLoS One 2010; 5:e10158. [PMID: 20405018 PMCID: PMC2854154 DOI: 10.1371/journal.pone.0010158] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 03/03/2010] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND The aging related decline of heat shock factor-1 (HSF1) signaling may be causally related to protein aggregation diseases. To model such disease, we tried to cripple HSF1 signaling in the Xenopus tadpole. RESULTS Over-expression of heat shock factor binding protein-1 did not inhibit the heat shock response in Xenopus. RNAi against HSF1 mRNA inhibited the heat shock response by 70% in Xenopus A6 cells, but failed in transgenic tadpoles. Expression of XHSF380, a dominant-negative HSF1 mutant, was embryonic lethal, which could be circumvented by delaying expression via a tetracycline inducible promoter. HSF1 signaling is thus essential for embryonic Xenopus development. Surprisingly, transgenic expression of the XHSF380 or of full length HSF1, whether driven by a ubiquitous or a neural specific promoter, was not detectable in the larval brain. CONCLUSIONS Our finding that the majority of neurons, which have little endogenous HSF1, refused to accept transgene-driven expression of HSF1 or its mutant suggests that HSF1 levels are strictly controlled in neuronal tissue.
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Affiliation(s)
- Ron P. Dirks
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Remon van Geel
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Sanne M. M. Hensen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Siebe T. van Genesen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Nicolette H. Lubsen
- Department of Biomolecular Chemistry, Radboud University Nijmegen, Nijmegen, The Netherlands
- * E-mail:
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Hageman J, Rujano MA, van Waarde MAWH, Kakkar V, Dirks RP, Govorukhina N, Oosterveld-Hut HMJ, Lubsen NH, Kampinga HH. A DNAJB chaperone subfamily with HDAC-dependent activities suppresses toxic protein aggregation. Mol Cell 2010; 37:355-69. [PMID: 20159555 DOI: 10.1016/j.molcel.2010.01.001] [Citation(s) in RCA: 250] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 09/22/2009] [Accepted: 11/24/2009] [Indexed: 11/25/2022]
Abstract
Misfolding and aggregation are associated with cytotoxicity in several protein folding diseases. A large network of molecular chaperones ensures protein quality control. Here, we show that within the Hsp70, Hsp110, and Hsp40 (DNAJ) chaperone families, members of a subclass of the DNAJB family (particularly DNAJB6b and DNAJB8) are superior suppressors of aggregation and toxicity of disease-associated polyglutamine proteins. The antiaggregation activity is largely independent of the N-terminal Hsp70-interacting J-domain. Rather, a C-terminal serine-rich (SSF-SST) region and the C-terminal tail are essential. The SSF-SST region is involved in substrate binding, formation of polydisperse oligomeric complexes, and interaction with histone deacetylases (HDAC4, HDAC6, SIRT2). Inhibiting HDAC4 reduced DNAJB8 function. DNAJB8 is (de)acetylated at two conserved C-terminal lysines that are not involved in substrate binding, but do play a role in suppressing protein aggregation. Combined, our data provide a functional link between HDACs and DNAJs in suppressing cytotoxic protein aggregation.
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Affiliation(s)
- Jurre Hageman
- Department of Cell Biology, Section of Radiation and Stress Cell Biology, University Medical Center Groningen and University of Groningen, 9700 RB Groningen, The Netherlands
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Wieten L, van der Zee R, Goedemans R, Sijtsma J, Serafini M, Lubsen NH, van Eden W, Broere F. Hsp70 expression and induction as a readout for detection of immune modulatory components in food. Cell Stress Chaperones 2010; 15:25-37. [PMID: 19472075 PMCID: PMC2866976 DOI: 10.1007/s12192-009-0119-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 04/19/2009] [Indexed: 02/02/2023] Open
Abstract
Stress proteins such as heat shock proteins (Hsps) are up-regulated in cells in response to various forms of stress, like thermal and oxidative stress and inflammation. Hsps prevent cellular damage and increase immunoregulation by the activation of anti-inflammatory T-cells. Decreased capacity for stress-induced Hsp expression is associated with immune disorders. Thus, therapeutic boosting Hsp expression might restore or enhance cellular stress resistance and immunoregulation. Especially food- or herb-derived phytonutrients may be attractive compounds to restore optimal Hsp expression in response to stress. In the present study, we explored three readout systems to monitor Hsp70 expression in a manner relevant for the immune system and evaluated novel Hsp co-inducers. First, intracellular staining and analysis by flow cytometry was used to detect stress and/or dietary compound induced Hsp70 expression in multiple rodent cell types efficiently. This system was used to screen a panel of food-derived extracts with potent anti-oxidant capacity. This strategy yielded the identity of several new enhancers of stress-induced Hsp70 expression, among them carvacrol, found in thyme and oregano. Second, CD4(+) T-cell hybridomas were generated that specifically recognized an immunodominant Hsp70 peptide. These hybridomas were used to show that carvacrol enhanced Hsp70 levels increased T-cell activation. Third, we generated a DNAJB1-luc-O23 reporter cell line to show that carvacrol increased the transcriptional activation of a heat shock promoter in the presence of arsenite. These assay systems are generally applicable to identify compounds that affect the Hsp level in cells of the immune system.
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Affiliation(s)
- Lotte Wieten
- Department of Infectious Diseases and Immunology, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Ruurd van der Zee
- Department of Infectious Diseases and Immunology, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Renske Goedemans
- Department of Infectious Diseases and Immunology, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Jeroen Sijtsma
- Department of Infectious Diseases and Immunology, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Mauro Serafini
- Antioxidant Research Laboratory, Unit of Human Nutrition, INRAN, Via Ardeatina 546, 00178 Rome, Italy
| | - Nicolette H. Lubsen
- Department of Biomolecular Chemistry, Faculty of Science, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Willem van Eden
- Department of Infectious Diseases and Immunology, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
| | - Femke Broere
- Department of Infectious Diseases and Immunology, Utrecht University, Yalelaan 1, 3584 CL Utrecht, The Netherlands
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Kidane AH, Heinrich G, Dirks RPH, de Ruyck BA, Lubsen NH, Roubos EW, Jenks BG. Differential neuroendocrine expression of multiple brain-derived neurotrophic factor transcripts. Endocrinology 2009; 150:1361-8. [PMID: 19008311 DOI: 10.1210/en.2008-0993] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is a neurotrophin with important growth-promoting properties. We report here the first characterization of a BDNF gene in an amphibian, Xenopus laevis, and demonstrate that environmental factors can activate this gene in a promoter-specific fashion. The Xenopus BDNF gene contains six promoter-specific 5'-exons and one 3'-protein-encoding exon. We examined the expression of promoter-specific transcripts in Xenopus neuroendocrine melanotrope cells. These cells make a good model to study how environmental factors control gene expression. In animals placed on a black background melanotrope cells more actively produce and release alphaMSH than in animals on a white background. BDNF is cosequestered and coreleased with alphaMSH and stimulates biosynthesis of proopiomelanocortin (POMC), the precursor protein for alphaMSH. Our analysis of the expression of the BDNF transcripts revealed that there is differential use of some BDNF promoters in melanotrope cells, depending on the adaptation state of the frog. During black-background adaptation, stimulation of expression of BDNF transcript IV preceded that of the POMC transcript, suggesting the BDNF gene is an effector gene for POMC expression. The possible mechanisms regulating expression of the various transcripts are discussed on the basis of the potential calcium- and cAMP-responsive elements in the promoter region of exon IV. Finally, we show that the upstream open reading frames of BDNF transcripts I and IV markedly decrease BDNF translation efficiency, giving the first indication for a functional role of untranslated BDNF exons.
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Affiliation(s)
- Adhanet H Kidane
- Department of Cellular Animal Physiology, Radboud University Nijmegen, Nijmegen, The Netherlands
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Abstract
The orientation of closely linked genes in mammalian genomes is not random: there are more head-to-head (h2h) gene pairs than expected. To understand the origin of this enrichment in h2h gene pairs, we have analyzed the phylogenetic distribution of gene pairs separated by less than 600 bp of intergenic DNA (gene duos). We show here that a lack of head-to-tail (h2t) gene duos is an even more distinctive characteristic of mammalian genomes, with the platypus genome as the only exception. In nonmammalian vertebrate and in nonvertebrate genomes, the frequency of h2h, h2t, and tail-to-tail (t2t) gene duos is close to random. In tetrapod genomes, the h2t and t2t gene duos are more likely to be part of a larger gene cluster of closely spaced genes than h2h gene duos; in fish and urochordate genomes, the reverse is seen. In human and mouse tissues, the expression profiles of gene duos were skewed toward positive coexpression, irrespective of orientation. The organization of orthologs of both members of about 40% of the human gene duos could be traced in other species, enabling a prediction of the organization at the branch points of gnathostomes, tetrapods, amniotes, and euarchontoglires. The accumulation of h2h gene duos started in tetrapods, whereas that of h2t and t2t gene duos only started in amniotes. The apparent lack of evolutionary conservation of h2t and t2t gene duos relative to that of h2h gene duos is thus a result of their relatively late origin in the lineage leading to mammals; we show that once they are formed h2t and t2t gene duos are as stable as h2h gene duos.
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Affiliation(s)
- Erik Franck
- Biomolecular Chemistry, 271 Nijmegen Center of Molecular Life Science, Radboud University Nijmegen, Nijmegen, The Netherlands
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15
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Marín-Vinader L, van Genesen ST, Lubsen NH. mRNA made during heat shock enters the first round of translation. ACTA ACUST UNITED AC 2006; 1759:535-42. [PMID: 17118471 DOI: 10.1016/j.bbaexp.2006.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Revised: 10/12/2006] [Accepted: 10/16/2006] [Indexed: 11/26/2022]
Abstract
To determine whether mRNA synthesized during a heat shock is translated at least once in spite of the strong inhibition of translation by heat shock, we used nonsense-mediated decay (NMD) as an assay since NMD requires a round of translation. As NMD substrate we used the human psigammaE-crystallin gene, which contains a premature termination codon, and as control, its close relative, the human gammaD-crystallin gene, both placed under control of the Hsp70 promoter. We show that no spliced psigammaE-crystallin mRNA can be detected in heat shocked cells, suggesting that NMD resumes as soon as splicing is restored. We further show that newly synthesized mRNAs co-sediment with the 40S ribosomal subunits, indicating that the transcripts are recruited to the translation machinery but are stalled at the translation initiation stage. Using fluorescence loss in photobleaching (FLIP) we show that cytoplasmic EGFP-CBP20 is immobile in heat shocked cells. CBP20 is part of the cap binding complex which is thought to direct the first round of translation. Together our data suggest that all mRNAs made during heat shock enter the pioneer round of translation.
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Affiliation(s)
- Laura Marín-Vinader
- Department of Biochemistry 271, Radboud University of Nijmegen. P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
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16
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Malecaze F, Decha A, Serre B, Penary M, Duboue M, Berg D, Levade T, Lubsen NH, Kremer EJ, Couderc B. Prevention of posterior capsule opacification by the induction of therapeutic apoptosis of residual lens cells. Gene Ther 2006; 13:440-8. [PMID: 16251995 DOI: 10.1038/sj.gt.3302667] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Posterior capsule opacification (PCO) is a common complication of cataract surgery. Using adenovirus(Ad)-mediated gene transfer, we overexpressed the proapoptotic molecules p53, procaspase 3, Bax, and TRAIL to induce therapeutic programmed cell death of residual lens cells to prevent PCO. Overexpressed TRAIL did not induce apoptosis in cultured rabbit lens cells or in human lens cells. Overexpressed p53 induced apoptosis of lens cells in vitro and ex vivo, but was unable to prevent PCO in vivo. Overexpressed procaspase 3 was associated with engagement of many components of the apoptotic pathway, including cleavage of intracellular caspase targets such as PARP and inter-nucleosome DNA fragmentation. Even when only slightly overexpressed, Bax caused apoptosis of transduced rabbit and human lens cells by engaging the mitochondrial pathway, including catalytic activation of the caspases. A single in vivo injection of Ad vectors expressing either Bax or procaspase 3 into the capsular bag at the end of phacoemulsification prevented PCO in rabbits. These experiments show that Ad-mediated Bax or procaspase 3 overexpression is capable of inducing therapeutic programmed cell death in vitro and in vivo in residual lens cells and preventing PCO in a rabbit model of PCO. Manipulation of proapoptotic molecule expression could be a novel gene therapy approach for prevention of PCO.
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Affiliation(s)
- F Malecaze
- INSERM U563, Department Ophtalmologie et Pathologie des épithéliums, Hôpital Purpan, Toulouse, France.
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17
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Marín-Vinader L, Onnekink C, van Genesen ST, Slingsby C, Lubsen NH. In vivo heteromer formation. Expression of soluble betaA4-crystallin requires coexpression of a heteromeric partner. FEBS J 2006; 273:3172-82. [PMID: 16774643 DOI: 10.1111/j.1742-4658.2006.05326.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The beta-crystallins are a family of long-lived, abundant structural proteins that are coexpressed in the vertebrate lens. As beta-crystallins form heteromers, a process that involves transient exposure of hydrophobic interfaces, we have examined whether in vivobeta-crystallin assembly is enhanced by protein chaperones, either small heat shock proteins, Hsp27 or alphaB-crystallin, or Hsp70. We show here that betaA4-crystallin is abundantly expressed in HeLa cells, but rapidly degraded, irrespective of the presence of Hsp27, alphaB-crystallin or Hsp70. Degradation is even enhanced by Hsp70. Coexpression of betaA4-crystallin with betaB2-crystallin yielded abundant soluble betaA4-betaB2-crystallin heteromers; betaB1-crystallin was much less effective in solubilizing betaA4-crystallin. As betaB2-crystallin competed for betaA4-crystallin with Hsp70 and the proteasomal degradation pathway, betaB2-crystallin probably captures an unstable betaA4-crystallin intermediate. We suggest that the proper folding of betaA4-crystallin is not mediated by general chaperones but requires a heteromeric partner, which then also acts as a dedicated chaperone towards betaA4-crystallin.
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Malecaze F, Lubsen NH, Serre B, Decha A, Duboue M, Penary M, Berg D, Arnaud JD, Titeux M, Kremer EJ, Couderc B. Lens cell targetting for gene therapy of prevention of posterior capsule opacification. Gene Ther 2006; 13:1422-9. [PMID: 16724094 DOI: 10.1038/sj.gt.3302790] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Posterior capsule opacification is the main complication of cataract surgery. Using adenovirus-mediated gene transfer, we recently reported that it was feasible to prevent PCO by overexpressing pro-apoptotic molecules such as pro-caspase 3 or Bax in the residual lens epithelial cells post-cataract surgery. However, this approach is feasible only if gene transfer can be restricted to the residual cells responsible for PCO. Initially, we tested an adenovirus (human serotype 5, HAd5), a lentivirus (HIV) and an oncoretrovirus (MLV) vector for the their in vivo transduction efficiency of rabbit lens cells. We found that HAd5 vectors were the most efficient (>90% of the cells could be transduced). Six potential lens-specific promoters were then cloned into HAd5 vectors and assayed for their ability to target expression to a specific population of cells, using in vitro, ex vivo and in vivo rabbit tissues and human lens capsular bags. We found that the LEP503, MIP and Filensin promoters induced strong lens-specific expression of a reporter gene, in human lens cells. Following this ex vivo assay, we showed in a rabbit PCO model that gene transfer could be spatially restricted to the capsular bag by confining the vector with Matrigel. Our combined approach using a lens-specific promoter and a biocompatible gel should render feasible a novel therapeutic strategy for PCO that targets the remaining lens cells.
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Affiliation(s)
- F Malecaze
- INSERM U563, Department of Ophtalmologie et Pathologie des épithéliums, UPS, Faculté de Médecine Toulouse Rangueil, France
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19
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Doerwald L, van Genesen ST, Onnekink C, Marín-Vinader L, de Lange F, de Jong WW, Lubsen NH. The effect of alphaB-crystallin and Hsp27 on the availability of translation initiation factors in heat-shocked cells. Cell Mol Life Sci 2006; 63:735-43. [PMID: 16505970 DOI: 10.1007/s00018-005-5582-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The mechanism of the translational thermotolerance provided by the small heat shock proteins (sHsps) alphaB-crystallin or Hsp27 is unknown. We show here that Hsp27, but not alphaB-crystallin, increased the pool of mobile stress granule-associated enhanced green fluorescent protein (EGFP)-eukaryotic translation initiation factor (eIF)4E in heat-shocked cells, as determined by fluorescence recovery after photobleaching. Hsp27 also partially prevented the sharp decrease in the pool of mobile cytoplasmic EGFP-eIF4G. sHsps did not prevent the phosphorylation of eIF2alpha by a heat shock, but promoted dephosphorylation during recovery. Expression of the C-terminal fragment of GADD34, which causes constitutive dephosphorylation of eIF2alpha, fully compensated for the stimulatory effect of alphaB-crystallin on protein synthesis in heat-shocked cells, but only partially for that of Hsp27. Our data show that sHsps do not prevent the inhibition of protein synthesis upon heat shock, but restore translation more rapidly by promoting the dephosphorylation of eIF2alpha and, in the case of Hsp27, the availability of eIF4E and eIF4G.
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Affiliation(s)
- L Doerwald
- Department of Biochemistry 271, NCMLS, Radboud University Nijmegen, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands,
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20
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Shimeld SM, Purkiss AG, Dirks RPH, Bateman OA, Slingsby C, Lubsen NH. Urochordate betagamma-crystallin and the evolutionary origin of the vertebrate eye lens. Curr Biol 2006; 15:1684-9. [PMID: 16169492 DOI: 10.1016/j.cub.2005.08.046] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2005] [Revised: 08/05/2005] [Accepted: 08/09/2005] [Indexed: 11/22/2022]
Abstract
A refracting lens is a key component of our image-forming camera eye; however, its evolutionary origin is unknown because precursor structures appear absent in nonvertebrates. The vertebrate betagamma-crystallin genes encode abundant structural proteins critical for the function of the lens. We show that the urochordate Ciona intestinalis, which split from the vertebrate lineage before the evolution of the lens, has a single gene coding for a single domain monomeric betagamma-crystallin. The crystal structure of Ciona betagamma-crystallin is very similar to that of a vertebrate betagamma-crystallin domain, except for paired, occupied calcium binding sites. The Ciona betagamma-crystallin is only expressed in the palps and in the otolith, the pigmented sister cell of the light-sensing ocellus. The Ciona betagamma-crystallin promoter region targeted expression to the visual system, including lens, in transgenic Xenopus tadpoles. We conclude that the vertebrate betagamma-crystallins evolved from a single domain protein already expressed in the neuroectoderm of the prevertebrate ancestor. The conservation of the regulatory hierarchy controlling betagamma-crystallin expression between organisms with and without a lens shows that the evolutionary origin of the lens was based on co-option of pre-existing regulatory circuits controlling the expression of a key structural gene in a primitive light-sensing system.
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Affiliation(s)
- Sebastian M Shimeld
- Department of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford OX1 3PS, United Kingdom.
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21
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Marin-Vinader L, Shin C, Onnekink C, Manley JL, Lubsen NH. Hsp27 enhances recovery of splicing as well as rephosphorylation of SRp38 after heat shock. Mol Biol Cell 2005; 17:886-94. [PMID: 16339078 PMCID: PMC1356597 DOI: 10.1091/mbc.e05-07-0596] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A heat stress causes a rapid inhibition of splicing. Exogenous expression of Hsp27 did not prevent that inhibition but enhanced the recovery of splicing afterward. Another small heat shock protein, alphaB-crystallin, had no effect. Hsp27, but not alphaB-crystallin, also hastened rephosphorylation of SRp38-dephosphorylated a potent inhibitor of splicing-after a heat shock, although it did not prevent dephosphorylation by a heat shock. The effect of Hsp27 on rephosphorylation of SRp38 required phosphorylatable Hsp27. A Hsp90 client protein was required for the effect of Hsp27 on recovery of spicing and on rephosphorylation of SRp38. Raising the Hsp70 level by either a pre-heat shock or by exogenous expression had no effect on either dephosphorylation of SRp38 during heat shock or rephosphorylation after heat shock. The phosphatase inhibitor calyculin A prevented dephosphorylation of SRp38 during a heat shock and caused complete rephosphorylation of SRp38 after a heat shock, indicating that cells recovering from a heat shock are not deficient in kinase activity. Together our data show that the activity of Hsp27 in restoring splicing is not due to a general thermoprotective effect of Hsp27, but that Hsp27 is an active participant in the (de)phosphorylation cascade controlling the activity of the splicing regulator SRp38.
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Affiliation(s)
- Laura Marin-Vinader
- Department of Biochemistry, Radboud University Nijmegen, 6500 HB Nijmegen, The Netherlands
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22
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Annunziata O, Pande A, Pande J, Ogun O, Lubsen NH, Benedek GB. Oligomerization and Phase Transitions in Aqueous Solutions of Native and Truncated Human βB1-Crystallin. Biochemistry 2005; 44:1316-28. [PMID: 15667225 DOI: 10.1021/bi048419f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human betaB1-crystallin is a major eye-lens protein that undergoes in vivo truncation at the N-terminus with aging. By studying native betaB1 and truncated betaB1DeltaN41, which mimics an age-related in vivo truncation, we have determined quantitatively the effect of truncation on the oligomerization and phase transition properties of betaB1 aqueous solutions. The oligomerization studies show that the energy of attraction between the betaB1DeltaN41 proteins is about 10% greater than that of the betaB1 proteins. We have found that betaB1DeltaN41 aqueous solutions undergo two distinct types of phase transitions. The first phase transition involves an initial formation of thin rodlike assemblies, which then evolve to form crystals. The induction time for the formation of rodlike assemblies is sensitive to oligomerization. The second phase transition can be described as liquid-liquid phase separation (LLPS) accompanied by gelation within the protein-rich phase. We refer to this process as heterogeneous gelation. These two phase transitions are not observed in the case of betaB1 aqueous solutions. However, upon the addition of poly(ethylene glycol) (PEG), we observe heterogeneous gelation also for betaB1. Our PEG experiments allow us to estimate the difference in phase separation temperatures between betaB1 and betaB1DeltaN41. This difference is consistent with the increase in energy of attraction found in our oligomerization studies. Our work suggests that truncation is a cataractogenic modification since it favors protein condensation and the consequent formation of light scattering elements, and highlights the importance of the N-terminus of betaB1 in maintaining lens transparency.
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Affiliation(s)
- Onofrio Annunziata
- Department of Physics, Center for Materials Science and Engineering, and Materials Processing Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA
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23
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Bloemendal H, de Jong W, Jaenicke R, Lubsen NH, Slingsby C, Tardieu A. Ageing and vision: structure, stability and function of lens crystallins. Prog Biophys Mol Biol 2004; 86:407-85. [PMID: 15302206 DOI: 10.1016/j.pbiomolbio.2003.11.012] [Citation(s) in RCA: 615] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The alpha-, beta- and gamma-crystallins are the major protein components of the vertebrate eye lens, alpha-crystallin as a molecular chaperone as well as a structural protein, beta- and gamma-crystallins as structural proteins. For the lens to be able to retain life-long transparency in the absence of protein turnover, the crystallins must meet not only the requirement of solubility associated with high cellular concentration but that of longevity as well. For proteins, longevity is commonly assumed to be correlated with long-term retention of native structure, which in turn can be due to inherent thermodynamic stability, efficient capture and refolding of non-native protein by chaperones, or a combination of both. Understanding how the specific interactions that confer intrinsic stability of the protein fold are combined with the stabilizing effect of protein assembly, and how the non-specific interactions and associations of the assemblies enable the generation of highly concentrated solutions, is thus of importance to understand the loss of transparency of the lens with age. Post-translational modification can have a major effect on protein stability but an emerging theme of the few studies of the effect of post-translational modification of the crystallins is one of solubility and assembly. Here we review the structure, assembly, interactions, stability and post-translational modifications of the crystallins, not only in isolation but also as part of a multi-component system. The available data are discussed in the context of the establishment, the maintenance and finally, with age, the loss of transparency of the lens. Understanding the structural basis of protein stability and interactions in the healthy eye lens is the route to solve the enormous medical and economical problem of cataract.
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Affiliation(s)
- Hans Bloemendal
- Department of Biochemistry, University of Nijmegen, 6500HB, The Netherlands
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24
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Doerwald L, van Rheede T, Dirks RP, Madsen O, Rexwinkel R, van Genesen ST, Martens GJ, de Jong WW, Lubsen NH. Sequence and Functional Conservation of the Intergenic Region Between the Head-to-Head Genes Encoding the Small Heat Shock Proteins αB-Crystallin and HspB2 in the Mammalian Lineage. J Mol Evol 2004; 59:674-86. [PMID: 15693623 DOI: 10.1007/s00239-004-2659-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An unexpected feature of the large mammalian genome is the frequent occurrence of closely linked head-to-head gene pairs. Close apposition of such gene pairs has been suggested to be due to sharing of regulatory elements. We show here that the head-to-head gene pair encoding two small heat shock proteins, alphaB-crystallin and HspB2, is closely linked in all major mammalian clades, suggesting that this close linkage is of selective advantage. Yet alphaB-crystallin is abundantly expressed in lens and muscle and in response to a heat shock, while HspB2 is abundant only in muscle and not upregulated by a heat shock. The intergenic distance between the genes for these two proteins in mammals ranges from 645 bp (platypus) to 1069 bp (opossum), with an average of about 900 bp; in chicken the distance was the same as in duck (1.6 kb). Phylogenetic footprinting and sequence alignment identified a number of conserved sequence elements close to the HspB2 promoter and two farther upstream. All known regulatory elements of the mouse alphaB-crystallin promoter are conserved, except in platypus and birds. The lens-specific region 1 (LSR1) and the heat shock elements (HSEs) lack in birds; in platypus the LSR1 is reduced to a Pax-6 site, while the Pax-6 site in LSR2 and a HSE are absent. Most likely the primordial mammalian alphaB-crystallin promoter had two LSRs and two HSEs. In transfection experiments the platypus alphaB-crystallin promoter retained heat shock responsiveness and lens expression. It also directed lens expression in Xenopus laevis transgenes, as did the HspB2 promoter of rat or blind mole rat. Deletion of the middle of the intergenic region including the upstream enhancer affected the activity of both the rat alphaB-crystallin and the HspB2 promoters, suggesting sharing of the enhancer region by the two promoters.
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Affiliation(s)
- Linda Doerwald
- Department of Biochemistry, Faculty of Science, University of Nijmegen, Nijmegen, The Netherlands
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25
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Abstract
Crystallins are long-lived proteins packed inside eye lens fiber cells that are essential in maintaining the transparency and refractive power of the eye lens. Members of the two-domain betagamma-crystallin family assemble into an array of oligomer sizes, forming intricate higher-order networks in the lens cell. Here we describe the 1.4 angstroms resolution crystal structure of a truncated version of human betaB1 that resembles an in vivo age-related truncation. The structure shows that unlike its close homolog, betaB2-crystallin, the homodimer is not domain swapped, but its domains are paired intramolecularly, as in more distantly related monomeric gamma-crystallins. However, the four-domain dimer resembles one half of the crystallographic bovine betaB2 tetramer and is similar to the engineered circular permuted rat betaB2. The crystal structure shows that the truncated betaB1 dimer is extremely well suited to form higher-order lattice interactions using its hydrophobic surface patches, linker regions, and sequence extensions.
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26
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Vinader LM, van Genesen ST, de Jong WW, Lubsen NH. Influence of hormones and growth factors on lens protein composition: the effect of dexamethasone and PDGF-AA. Mol Vis 2003; 9:723-9. [PMID: 14685140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
PURPOSE To investigate the effect of hormones and ocular growth factors on the expression of alpha-, beta-, and gamma-crystallins in rat lens epithelial and fiber cells. METHODS PDGF-AA, EGF, NGF, M-CSF, BMP-2, BMP-4, dexamethasone, and estrogen were tested for their ability to alter the spectrum of crystallins in explanted newborn rat lens epithelial cells or in vitro differentiating newborn rat lens fiber cells. The accumulation of alphaA-, aB-, betaA3/1-, betaB2-, and gamma-crystallin was measured by western blot and dot blot analysis. The morphology of the rat lens explants after culture was examined by hematoxylin-eosin staining, while crystallins were localized by immunofluorescence. RESULTS Only dexamethasone and PDGF-AA showed an effect on relative crystallin levels. In the presence of dexamethasone the amount of alphaB-crystallin was increased in lens epithelial cells, but dexamethasone did not affect the crystallin spectrum in fiber cells. In rat lens epithelial explants cultured with PDGF-AA an increase in beta- and gamma-crystallin expression was seen. The spectrum of beta- and gamma-crystallins synthesized differed from that present in lens fiber cells. The cells expressing beta- and gamma-crystallin after culture with PDGF-AA were scattered in the epithelial cell layer and retained an epithelial morphology. PDGF-AA did not change the spectrum of crystallins synthesized in lens fiber cells but did enhance the rate of fiber cell differentiation, in agreement with results of others. CONCLUSIONS Both dexamethasone and PDGF-AA influence crystallin gene expression in cultured rat lens epithelial cells. Dexamethasone enhances the expression of alphaB-crystallin while culturing in the presence of PDGF-AA caused an increase in beta- as well as gamma-crystallin synthesis. Since at least the gamma-crystallin genes are known to be silenced in epithelial cells by DNA methylation, PDGF-AA may be able to induce one of the steps towards fiber cell differentiation in some epithelial cells.
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27
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Abstract
Crystallins are bulk structural proteins of the eye lens that have to last a life time. They gradually become modified with age, denature and form light scattering centres. High thermodynamic and kinetic stability of the crystallins enables them to resist unfolding and delay cataract. Here we have made recombinant human betaA1-, betaA3-, and betaA4-crystallins. The betaA3-crystallin formed higher oligomers that lead to precipitation at ambient temperature. Heat-induced precipitation of betaA3-crystallin was compared with human and calf betaB2-crystallins, showing that the human proteins start to precipitate above 50 degrees C while the calf betaB2-crystallin stays in solution even when unfolded. The stabilities of these human acidic beta-crystallin homo-oligomers have been estimated by measuring their unfolding in urea at neutral pH. BetaA3/1/betaB1 and betaA4/betaB1-crystallin hetero-oligomers have been prepared from homo-oligomers by subunit exchange. The resolution of the methodology used was insufficient to detect a stabilization of the betaA4-crystallin subunit in the hetero-oligomer, the betaA1-crystallin subunit was clearly stabilized by its interaction with betaB1-crystallin. Circular dichroism and fluorescence spectroscopies show that homo-dimer surface tryptophans become buried in the betaA3/1/betaB1-crystallin hetero-dimer concomitant with changes in polypeptide chain conformation.
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Affiliation(s)
- O A Bateman
- Department of Crystallography, Birkbeck College, London, UK
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28
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Doerwald L, Onnekink C, van Genesen ST, de Jong WW, Lubsen NH. Translational thermotolerance provided by small heat shock proteins is limited to cap-dependent initiation and inhibited by 2-aminopurine. J Biol Chem 2003; 278:49743-50. [PMID: 14523008 DOI: 10.1074/jbc.m302914200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heat shock results in inhibition of general protein synthesis. In thermotolerant cells, protein synthesis is still rapidly inhibited by heat stress, but protein synthesis recovers faster than in naive heat-shocked cells, a phenomenon known as translational thermotolerance. Here we investigate the effect of overexpressing a single heat shock protein on cap-dependent and cap-independent initiation of translation during recovery from a heat shock. When overexpressing alphaB-crystallin or Hsp27, cap-dependent initiation of translation was protected but no effect was seen on cap-independent initiation of translation. When Hsp70 was overexpressed however, both cap-dependent and -independent translation were protected. This finding indicates a difference in the mechanism of protection mediated by small or large heat shock proteins. Phosphorylation of alphaB-crystallin and Hsp27 is known to significantly decrease their chaperone activity; therefore, we tested phosphorylation mutants of these proteins in this system. AlphaB-crystallin needs to be in its non-phosphorylated state to give protection, whereas phosphorylated Hsp27 is more potent in protection than the unphosphorylatable form. This indicates that chaperone activity is not a prerequisite for protection of translation by small heat shock proteins after heat shock. Furthermore, we show that in the presence of 2-aminopurine, an inhibitor of kinases, among which is double-stranded RNA-activated kinase, the protective effect of overexpressing alphaB-crystallin is abolished. The synthesis of the endogenous Hsps induced by the heat shock to test for thermotolerance is also blocked by 2-aminopurine. Most likely the protective effect of alphaB-crystallin requires synthesis of the endogenous heat shock proteins. Translational thermotolerance would then be a co-operative effect of different heat shock proteins.
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Affiliation(s)
- Linda Doerwald
- Department of Biochemistry, Faculty of Science, University of Nijmegen, 6500HB Nijmegen, The Netherlands
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29
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Putilina T, Skouri-Panet F, Prat K, Lubsen NH, Tardieu A. Subunit exchange demonstrates a differential chaperone activity of calf alpha-crystallin toward beta LOW- and individual gamma-crystallins. J Biol Chem 2003; 278:13747-56. [PMID: 12562766 DOI: 10.1074/jbc.m208157200] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The chaperone activity of native alpha-crystallins toward beta(LOW)- and various gamma-crystallins at the onset of their denaturation, 60 and 66 degrees C, respectively, was studied at high and low crystallin concentrations using small angle x-ray scattering (SAXS) and fluorescence energy transfer (FRET). The crystallins were from calf lenses except for one recombinant human gamma S. SAXS data demonstrated an irreversible doubling in molecular weight and a corresponding increase in size of alpha-crystallins at temperatures above 60 degrees C. Further increase is observed at 66 degrees C. More subtle conformational changes accompanied the increase in size as shown by changes in environments around tryptophan and cysteine residues. These alpha-crystallin temperature-induced modifications were found necessary to allow for the association with beta(LOW)- and gamma-crystallins to occur. FRET experiments using IAEDANS (iodoacetylaminoethylaminonaphthalene sulfonic acid)- and IAF (iodoacetamidofluorescein)-labeled subunits showed that the heat-modified alpha-crystallins retained their ability to exchange subunits and that, at 37 degrees C, the rate of exchange was increased depending upon the temperature of incubation, 60 or 66 degrees C. Association with beta(LOW)- (60 degrees C) or various gamma-crystallins (66 degrees C) resulted at 37 degrees C in decreased subunit exchange in proportion to bound ligands. Therefore, beta(LOW)- and gamma-crystallins were compared for their capacity to associate with alpha-crystallins and inhibit subunit exchange. Quite unexpectedly for a highly conserved protein family, differences were observed between the individual gamma-crystallin family members. The strongest effect was observed for gamma S, followed by h gamma Srec, gamma E, gamma A-F, gamma D, gamma B. Moreover, fluorescence properties of alpha-crystallins in the presence of bound beta(LOW)-and gamma-crystallins indicated that the formation of beta(LOW)/alpha- or gamma/alpha-crystallin complexes involved various binding sites. The changes in subunit exchange associated with the chaperone properties of alpha-crystallins toward the other lens crystallins demonstrate the dynamic character of the heat-activated alpha-crystallin structure.
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Affiliation(s)
- Tatiana Putilina
- Laboratoire de Minéralogie-Cristallographie, CNRS and P6-P7 Universities, Case 115, 4 Place Jussieu, F75252 Paris Cedex 05, France
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Kim YH, Kapfer DM, Boekhorst J, Lubsen NH, Bächinger HP, Shearer TR, David LL, Feix JB, Lampi KJ. Deamidation, but not truncation, decreases the urea stability of a lens structural protein, betaB1-crystallin. Biochemistry 2002; 41:14076-84. [PMID: 12437365 DOI: 10.1021/bi026288h] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Crystallins, the major structural proteins in the lens of the eye, are maintained with little turnover throughout the lifetime of the host. With time, lens crystallins undergo post-translational modifications that may play an important role in loss of vision during aging and cataract formation. Specific modifications include deamidation and truncation. Urea-induced denaturation was studied for recombinantly expressed wild-type betaB1 (WT), the deamidated mutant (Q204E), an N-terminally truncated mutant (betaB1(DeltaN41)), and other truncated versions of these proteins generated by calpain II digestion. Tryptophan fluorescence was used to monitor loss of global tertiary structure. Loss of secondary structure was followed by circular dichroism, and electron paramagnetic resonance site-directed spin labeling was used to monitor loss of tertiary structure selectively in the N-terminal domain. Our results indicated that the deamidated mutant was significantly destabilized relative to WT. Q204E showed a two-step denaturation curve with transitions at 4.1 and 7.2 M urea, whereas denaturation of WT occurred in a cooperative single step with a transition midpoint of 5.9 M urea. Unfolding of WT was completely reversible, whereas Q204E failed to fully refold. Prolonged incubation under denaturing conditions led to aggregation, which was also more pronounced for Q204E dimers than for WT. Truncation of 41 residues from the N-terminus or 47 and 5 residues from the N- and C-termini did not affect stability. These studies indicated that a single-site deamidation could significantly diminish the stability of lens betaB1-crystallin, supporting the idea that such modifications may play an important role in age-related cataract formation.
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Affiliation(s)
- Yung Hae Kim
- Department of Animal Sciences, Oregon State University, Corvallis, Oregon 97331, USA
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Abstract
The transcription factor c-Maf has been suggested to regulate the activity of gamma-crystallin promoters in lens fibre cells. We here show that the transactivation potential of c-Maf and MafB for the rat gammaD-crystallin Maf-responsive element (gammaD MARE) is dependent upon the cellular context and, using chimeric and single domain mutants, that c-Maf is most likely to be the cognate factor for the gammaD MARE in the lens. Transactivation of the gammaD MARE by c-Maf in lens cells was not enhanced by c-Fos or c-Jun and was not blocked by dominant negative c-Fos or c-Jun constructs. c-Maf can activate the gammaD MARE as a homodimer since activation of the gammaD-crystallin promoter in P19 embryonic carcinoma cells required only c-Maf, but none of a number of c-Fos and c-Jun family members tested. Transactivation by c-Maf was inhibited by activation of protein kinase A (PKA) (by signal transduction agonist forskolin) or of protein kinase C (PKC) (by signal transduction agonist tetradecanoyl phorbol acetate). Site-directed mutagenesis showed that this effect is not mediated by phosphorylation of the consensus PKA/PKC site in the extended DNA-binding domain, but likely involves activation of MAP kinase kinase, as inhibition by PD98059 increased transactivation by c-Maf.
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Affiliation(s)
- Azem Civil
- Department of Biochemistry, University of Nijmegen, Nijmegen, The Netherlands
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32
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Abstract
gammaS-crystallin is a major human lens protein found in the outer region of the eye lens, where the refractive index is low. Because crystallins are not renewed they acquire post-translational modifications that may perturb stability and solubility. In common with other members of the betagamma-crystallin superfamily, gammaS-crystallin comprises two similar beta-sheet domains. The crystal structure of the C-terminal domain of human gammaS-crystallin has been solved at 2.4 A resolution. The structure shows that in the in vitro expressed protein, the buried cysteines remain reduced. The backbone conformation of the "tyrosine corner" differs from that of other betagamma-crystallins because of deviation from the consensus sequence. The two C-terminal domains in the asymmetric unit are organized about a slightly distorted 2-fold axis to form a dimer with similar geometry to full-length two-domain family members. Two glutamines found in lattice contacts may be important for short range interactions in the lens. An asparagine known to be deamidated in human cataract is located in a highly ordered structural region.
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Affiliation(s)
- Andrew G Purkiss
- School of Crystallography, Birkbeck College, Malet Street, London WC1E 7HX, United Kingdom .
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33
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Abstract
The suggested common regulator of the eye lens crystallin genes is c-Maf. Maf responsive elements have been detected in a number of crystallin promoters including that of the rat betaB2-crystallin gene. The betaB2-crystallin gene is active in the post-natal lens and its mRNA reaches its maximal level in the rat lens 6 months after birth. Yet c-Maf has been reported to be present in the rat lens only up to 3 months of age. This discrepancy prompted an investigation into the role of the Maf responsive element (MARE) in the regulation of activity of the rat betaB2-crystallin promoter in rat lens fiber cells. Although betaB2 promoter activity is enhanced by c-Maf in both in vitro differentiating rat lens fiber cells and CHO cells, deletion of the betaB2 MARE, which was mapped to -143/-123, does not decrease betaB2 promoter activity in lens fiber cells. Furthermore, a dominant negative c-Maf construct did not inhibit activity of the betaB2 promoter in lens fiber cells. The data suggest that the betaB2 MARE does not play a major role in regulating activity of the betaB2 promoter. Rather, a putative Sox binding site at -164/-159 and a positive element at -14/-7 seem to be the prime regulatory elements.
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Affiliation(s)
- L Doerwald
- Department of Biochemistry, Faculty of Science, University of Nijmegen, 6500 HB Nijmegen, The Netherlands
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34
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Abstract
betaB1-crystallin plays an important role in the assembly of betaH-crystallin yet is known to be subject to N-terminal sequence truncations during human lens development and ageing. Here we have over-expressed human betaB1-crystallin, and various truncated forms in Escherichia coli and used mass spectrometry to monitor the monomer molecular weight. Gel permeation chromatography and laser light scattering have been used to estimate the assembly size of the various polypeptides as a function of protein concentration. The full-length betaB1-crystallin behaves as a dimer, like recombinant human betaB2-crystallin, but undergoes further self-association at high protein concentrations, unlike the betaB2-crystallin. Major truncations from the N-terminal extension lead to anomalous behaviour on gel permeation chromatography indicative of altered interactions with the column matrix, whereas light scattering indicated dimers at low protein concentration that self-associate as a function of protein concentration. Loss of 41 residues from the N-terminus, equivalent to an in vivo truncation site, resulted in temperature-dependent phase separation behaviour of the shortened betaB1-crystallin. Good crystals have been grown of a truncated version of human betaB1-crystallin using an in vitro cleavage protocol.
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Affiliation(s)
- O A Bateman
- Birkbeck College, Department of Crystallography, Malet Street, London, WC1E 7HX, UK
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35
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Abstract
Among lens crystallins, gamma-crystallins are particularly sensitive to oxidation, because of their high amount of Cys and Met residues. They have the reputation to induce, upon ageing, lens structural modifications leading to opacities. A combination of small angle X-ray scattering and chromatography was used to study the oxidation of gamma-crystallins. At pH 7.0, all the gamma-crystallins under study were checked to have the same structure in solution. Under gentle oxidation conditions at pH 8.0, human gammaS (hgammaS) and bovine gammaS (bgammaS) formed disulfide-linked dimers, whereas the other bgamma-crystallins did not. Cys20 was shown to be responsible for dimer formation since the C20S mutant only formed monomers. The hgammaS dimers were stable for weeks and did not form higher oligomers. In contrast, monomeric gammaS-crystallins freshly prepared at pH 8.0, and submitted to more drastic oxidation by X-ray induced free radicals, were rapidly transformed into higher oligomers. So, only extensive oxidation causing partial unfolding could be detrimental to the lens and linked to cataract formation. The gammaS-crystallins lack the temperature-induced opacification observed with the other gamma-crystallins and known as cold cataract. The oxidation-induced associative behaviour and cold cataract are therefore demonstrated to be uncoupled.
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Affiliation(s)
- F Skouri-Panet
- Laboratoire de Minéralogie-Cristallographie, CNRS-Universités Paris VI & VII, France.
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36
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Wenk M, Herbst R, Hoeger D, Kretschmar M, Lubsen NH, Jaenicke R. Gamma S-crystallin of bovine and human eye lens: solution structure, stability and folding of the intact two-domain protein and its separate domains. Biophys Chem 2000; 86:95-108. [PMID: 11026675 DOI: 10.1016/s0301-4622(00)00161-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Human and bovine gammaS-crystallin (HgammaS and BgammaS) and their isolated N- and C-terminal domains were cloned and expressed as recombinant proteins in E. coli. HgammaS and BgammaS are found to be authentic according to their spectral and hydrodynamic properties. Both full-length proteins and isolated domains are monomeric and exhibit high thermal and pH stabilities. The thermodynamic characterization made use of chemically and thermally-induced equilibrium unfolding transitions at varying pH. In spite of its exemplary two-domain structure, gammaS-crystallin does not show bimodal unfolding characteristics. In the case of BgammaS, at pH 7.0, the C-terminal domain is less stable than the N-terminal one, whereas for HgammaS the opposite holds true. Differential scanning calorimetry confirms the results of chemically-induced equilibrium unfolding transitions. Over the whole pH range between 2.0 and 11.5, HgammaS-crystallin and its isolated domains (HgammaS-N and HgammaS-C) follow the two-state model. The two-state unfolding of the intact two-domain protein points to the close similarity of the stabilities of the constituent domains. Obviously, interactions between the domains do not contribute significantly to the overall stability of gammaS-crystallin. In contrast, the structurally closely related gammaB-crystallin owes much of its extreme stability to domain interactions.
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Affiliation(s)
- M Wenk
- Institute of Biophysics and Physical Biochemistry, University of Regensburg, Germany
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37
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Civil A, van Genesen ST, Klok EJ, Lubsen NH. Insulin and IGF-I affect the protein composition of the lens fibre cell with possible consequences for cataract. Exp Eye Res 2000; 70:785-94. [PMID: 10843783 DOI: 10.1006/exer.2000.0846] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Explanted newborn rat lens epithelial cells were cultured with various concentrations of FGF-2 and/or insulin or IGF-I for 8-20 days. The accumulation of alphaA-, alphaB-, betaA3/1-, betaB2- and gammaA-F-crystallin was measured. During culture with insulin only, i.e. in the absence of fibre cell differentiation, alphaA- and alphaB-crystallin accumulated to the same level as found in differentiating cells. Culture of epithelial cells with IGF-I led to an increase in alphaB-crystallin, but not in alphaA-crystallin. The addition of insulin under differentiation conditions (in the presence of 25 ng ml(-1)FGF-2) augmented the accumulation of alphaA-crystallin 1.5-fold, the accumulation of betaB2-crystallin two-fold and the accumulation of gammaA-F-crystallin five-fold over that found with FGF-2 only. The accumulation of alphaB- and betaA3/1-crystallin was not affected by insulin in the presence of FGF-2. Adding IGF-I to fibre cells differentiating in the presence of 25 ng ml(-1)FGF-2 resulted in a 1.5-fold increase (of questionable statistical significance) in both alphaA- and alphaB-crystallin and a two to three-fold increase in gammaA-F-crystallin compared to cells cultured with FGF-2 only, no significant effect of IGF-I on the accumulation of betaA3/1- or betaB2-crystallin was found. Comparison of the levels of mRNA and protein suggests that insulin acts to increase the level of transcription. Our results show that the response of fibre cells to insulin or IGF-I differs. Hence, even though half the maximum dosage required for the insulin effect was rather high (between 0.1 and >5 micro g), the effect of insulin cannot be merely transmitted by the IGF-I receptor. Our data further predict that insulin or IGF-I increases the overall ratio of beta- and gamma-crystallin to alpha-crystallin in the fibre cell, which could predispose the lens to cataract.
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Affiliation(s)
- A Civil
- Departments of Molecular Biology and Biochemistry, University of Nijmegen, Nijmegen, The Netherlands
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38
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Pande A, Pande J, Asherie N, Lomakin A, Ogun O, King JA, Lubsen NH, Walton D, Benedek GB. Molecular basis of a progressive juvenile-onset hereditary cataract. Proc Natl Acad Sci U S A 2000; 97:1993-8. [PMID: 10688888 PMCID: PMC15742 DOI: 10.1073/pnas.040554397] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In a recent paper, patients with a progressive juvenile-onset hereditary cataract have been reported to have a point mutation in the human gammaD crystallin gene (Stephan, D. A., Gillanders, E., Vanderveen, D., Freas-Lutz, D., Wistow, G., Baxevanis, A. D., Robbins, C. M., VanAuken, A., Quesenberry, M. I., Bailey-Wilson, J., et al. (1999) Proc. Natl. Acad. Sci. USA 96, 1008-1012). This mutation results in the substitution of Arg-14 in the native protein by a Cys residue. It is not understood how this mutation leads to cataract. We have expressed recombinant wild-type human gammaD crystallin (HGD) and its Arg-14 to Cys mutant (R14C) in Escherichia coli and show that R14C forms disulfide-linked oligomers, which markedly raise the phase separation temperature of the protein solution. Eventually, R14C precipitates. In contrast, HGD slowly forms only disulfide-linked dimers and no oligomers. These data strongly suggest that the observed cataract is triggered by the thiol-mediated aggregation of R14C. The aggregation profiles of HGD and R14C are consistent with our homology modeling studies that reveal that R14C contains two exposed cysteine residues, whereas HGD has only one. Our CD, fluorescence, and differential scanning calorimetric studies show that HGD and R14C have nearly identical secondary and tertiary structures and stabilities. Thus, contrary to current views, unfolding or destabilization of the protein is not necessary for cataractogenesis.
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Affiliation(s)
- A Pande
- Department of Biology, Materials Processing Center, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA
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39
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40
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Abstract
The differentiation of rat lens epithelial cells to fibre cells can be mimicked using lens epithelial explants, which differentiate in vitro when exposed to fibroblast growth factor (FGF). A previous study demonstrated that FGF is required only for initiation of differentiation: once induced by FGF, differentiation can be maintained by insulin (as assessed by following the accumulation of fibre-cell specific crystallins). The aim of this investigation was to determine whether insulin-like growth factor 1 (IGF-1) can also maintain differentiation and to include a cellular analysis of explants undergoing insulin-or IGF-maintained differentiation in vitro. Measurement of the accumulation of alpha-, beta- and gamma-crystallins showed that IGF-1, like insulin, can replace FGF-2 in directing the pulses of alpha-, beta- and gamma-crystallin gene expression once differentiation is initiated by FGF-2. Cells in both the peripheral and the central region of the explants responded. Immunolocalization of alpha, beta- and gamma-crystallins in these explants showed that a 15 min pulse of FGF-2 triggered the differentiation of only a few cells, whereas a 12 hr pulse primed virtually all the cells for differentiation. This indicates that in explants, individual cells differ in the rate at which they can respond to FGF-2.
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Affiliation(s)
- E j Klok
- Department of Anatomy, Histology and Institute for Biomedical Research (F13), The University of Sydney, Sydney, NSW, 2006, Australia
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41
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Klok EJ, van Genesen ST, Civil A, Schoenmakers JG, Lubsen NH. Regulation of expression within a gene family. The case of the rat gammaB- and gammaD-crystallin promoters. J Biol Chem 1998; 273:17206-15. [PMID: 9642290 DOI: 10.1074/jbc.273.27.17206] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The six closely related and clustered rat gamma-crystallin genes, the gammaA- to gammaF-crystallin genes, are simultaneously activated in the embryonic lens but differentially shut down during postnatal development with the gammaB-crystallin gene, the last one to be active. We show here that developmental silencing of the gammaD-crystallin promoter correlates with delayed demethylation during lens fiber cell differentiation. Methylation silencing of the gammaD-crystallin promoter is a general effect and does not require the methylation of a specific CpG, nor does methylation interfere with factor binding to the proximal activator. In later development, the gammaD-crystallin promoter is also shut down earlier by a repressor that footprints to the -91/-78 region. A factor with identical properties is present in brain. Hence, a ubiquitous factor has been recruited as a developmental regulator by the lens. All gamma-crystallin promoters tested contain upstream silencers, but at least the gammaB-crystallin silencer is distinct from the gammaD-crystallin silencer. The gamma-crystallin promoters were found to share a proximal activator (the gamma-box; around -50), which behaves as a MARE. The gammaB-box is recognized with much lower avidity than the gammaD-box. By swapping elements between the gammaB- and the gammaD-crystallin promoter, we show that activation by the gammaB-box requires a directly adjacent -46/-38 AP-1 consensus site. These experiments also uncovered another positive element in the gammaD-crystallin promoter, around -10. In the context of the gammaD-crystallin promoter, this element is redundant; in the context of the gammaB-crystallin promoter, it can replace the -46/-38 element.
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Affiliation(s)
- E J Klok
- Department of Molecular Biology, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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42
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Basak AK, Kroone RC, Lubsen NH, Naylor CE, Jaenicke R, Slingsby C. The C-terminal domains of gammaS-crystallin pair about a distorted twofold axis. Protein Eng 1998; 11:337-44. [PMID: 9681865 DOI: 10.1093/protein/11.5.337] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
The 2-domain gammaS-crystallin, a highly conserved early evolutionary off-shoot of the gamma-crystallin family, is located in the water-rich region of eye lenses. The expressed C-terminal domain, gammaS-C, has been crystallized and the 2.56 A X-ray structure determined. There are two domains in the asymmetric unit which pair about a distorted twofold axis. One of the domains has an altered conformation in a highly conserved region of the protein, the tyrosine corner. The distorted gammaS-C dimer of domains is compared with the highly symmetrical, equivalent recombinant dimer of C-terminal domains from gammaB-crystallin. Sequence changes close to the interface, that distinguish gammaS from the other gamma-crystallins, are examined in order to evaluate their role in symmetrical domain pairing.
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Affiliation(s)
- A K Basak
- Department of Crystallography, Birkbeck College, London, UK
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44
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Brunekreef GA, van Genesen ST, Destrée OH, Lubsen NH. Extralenticular expression of Xenopus laevis alpha-, beta-, and gamma-crystallin genes. Invest Ophthalmol Vis Sci 1997; 38:2764-71. [PMID: 9418729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
PURPOSE Extralenticular expression of alpha- and beta-crystallin genes has been demonstrated in mammals and expression of gamma-crystallin genes has been shown in Xenopus laevis. To determine a possible correlation between lens determination and crystallin gene expression, the site of expression of (a member of) the alpha-, beta-, and gamma-crystallin gene families was observed before and during lens formation in X. laevis. METHODS The partial complementary DNAs (cDNAs) of alpha A- and beta A4-crystallin and a gamma-crystallin were cloned from an X. laevis lens cDNA library. The corresponding antisense RNAs were used to analyze the expression of these genes during X. laevis development by wholemount in situ hybridization. RESULTS Expression of the beta A4- and gamma-crystallin (but not alpha-crystallin) genes could first be detected in the animal cap of the X. laevis gastrula. The beta A4- and gamma-crystallin messengers were also found in the first stage of lens development, when the ectodermal tissue overlying the optic vesicle thickens to form the lens placode. alpha A-crystallin messenger RNAs were only detectable when the lens epithelial cells were formed. CONCLUSIONS In contrast to observations in most vertebrates, expression of the beta A4- and gamma-crystallin genes was observed to precede that of the alpha A-crystallin gene during lens development of X. laevis, reflecting the determination that in amphibians, the (presumptive) fiber cells are formed before the epithelial cells, whereas in vertebrates, the order is reversed. Expression of beta A4- and gamma-crystallin genes in the ectodermal tissue of the X. laevis gastrula shows that these genes are expressed when this tissue gains competence for lens formation.
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Affiliation(s)
- G A Brunekreef
- Department of Molecular Biology, University of Nijmegen, The Netherlands
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45
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Leenders WP, van Genesen ST, Schoenmakers JG, van Zoelen EJ, Lubsen NH. Synergism between temporally distinct growth factors: bFGF, insulin and lens cell differentiation. Mech Dev 1997; 67:193-201. [PMID: 9392516 DOI: 10.1016/s0925-4773(97)00121-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Fibroblast growth factors (FGFs) are the only known factors that can induce differentiation of the mammalian lens epithelial cell, while insulin acts only as a mitogen, not as a morphogen. We show here that insulin enhances expression of the alphaA-crystallin gene in lens epithelial cells and induces the synthesis of lens fibre cell specific betaB2- and gamma-crystallins in early differentiated fibre cells. Different signal transduction pathways are required for bFGF or insulin maintained fibre cell differentiation. A 15 min preincubation with bFGF was sufficient for the lens epithelial cells to become competent to undergo insulin maintained differentiation. The phorbol ester TPA could replace bFGF. The bFGF instructed competence to differentiate decays with a half-life of about 30 h. Hence, bFGF and insulin can act in concert to produce a differentiated phenotype even when they are not present simultaneously.
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Affiliation(s)
- W P Leenders
- Department of Molecular Biology and Cell Biology, University of Nijmegen, The Netherlands
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46
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Abstract
The pattern of factors binding to either the Sp1-consensus sequence or to the octamer sequence during in vitro rat lens fibre cell differentiation has been examined by electrophoretic mobility shift assays. With the Sp1-consensus sequence as probe, two major and four minor bands were seen. Three bands were present at all stages of differentiation, two are lost during terminal differentiation and one is present only in late differentiating cells. The octamer probe yielded three bands, which co-migrate with Oct2, Oct3 and Oct7. The exact identity of these factors has not been established. The Oct3-like band was detected only in epithelial cell extracts, the other two bands were also found in fibre cell extracts, whereby the intensity of the Oct2-like band decreased relative to that of the Oct7-like band during differentiation. In transfection studies, a rat gamma D-crystallin promoter in which the proximal activator has been replaced by a dimer of the Sp1-consensus sequence showed a gradual increase in activity with differentiation, in contrast, a similar construct with an octamer dimer was active only during late differentiation and mimicked the pattern of activation of the parental gamma D-crystallin promoter.
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Affiliation(s)
- G A Brunekreef
- Department of Molecular Biology, University of Nijmegen, The Netherlands
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47
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Abstract
The polymerase chain reaction was used to amplify a cDNA sequence encoding the human alphaB-crystallin. The amplified cDNA fragment was cloned into the bacterial expression vector pMAL-c2 and expressed as a soluble fusion protein coupled to maltose-binding protein (MBP). After maltose affinity chromatography and cleavage from MBP by Factor Xa, the recombinant human alphaB-crystallin was separated from MBP and Factor Xa by anion exchange chromatography. Recombinant alphaB-crystallin was characterized by SDS-polyacrylamide electrophoresis (PAGE), Western immunoblot analysis, Edman degradation, circular dichroism spectroscopy, and size exclusion chromatography. The purified crystallin migrated on SDS-PAGE to an apparent molecular weight (Mr approximately 22,000) that corresponded to total native human alpha-crystallin and was recognized on Western immunoblots by antiserum raised against human alphaB-crystallin purified from lens homogenates. Chemical sequencing, circular dichroism spectroscopy, and size exclusion chromatography demonstrated that the recombinant crystallin had properties similar or identical to its native counterpart. Both recombinant alphaB-crystallin and MBP-alphaB fusion protein associated to form high molecular weight complexes that displayed chaperone-like function by inhibiting the aggregation of alcohol dehydrogenase at 37 degrees C and demonstrated the importance of the C-terminal domain of alphaB-crystallin for chaperone-like activity.
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Affiliation(s)
- P J Muchowski
- Department of Biological Structure, University of Washington, Seattle, Washington 98195-7420, USA
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48
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Leenders WP, van Hinsbergh VW, van Genesen ST, Schoenmakers JG, van Zoelen EJ, Lubsen NH. Mutants of basic fibroblast growth factor identify different cellular response programs. Growth Factors 1997; 14:213-28. [PMID: 9386987 DOI: 10.3109/08977199709021521] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mutations, expected to affect the intracellular routing, i.e. additional nuclear localization sequences (NLS; the natural 23 kDa isoform and a 17D27R mutant) and/or a deletion of amino acids 26-29 (23 delta 26-29 and 17 delta 26-29), were introduced in basic fibroblast growth factor (bFGF). The mutants were assayed for their mitotic activity and their capacity to induce a tissue-specific response in human umbilical vein endothelial cells [HUVECs; induction of urokinase plasminogen activator receptor (u-PAR)], or in rat lens epithelial cells (fibre cell differentiation). In HUVECs, the 17D27R mutant had wild type activity, the 23 kDa and the delta 26-29 proteins were impaired in the induction of both mitosis and u-PAR. The delta 26-29 proteins, but not the 23 kDa protein or 17D27R mutant, were also impaired in receptor binding in that they bound only to a subset of receptors. The concentration of 17 kDa bFGF required for half maximal u-PAR response was 30 fold higher than for the half maximal 3H-thymidine incorporation. Addition of an NLS to bFGF strongly inhibited the induction of fibre cell differentiation, though it had little effect on the stimulation of DNA synthesis. The 17 delta 26-29 kDa mutant had wild type differentiation activity but was a poor mitogen for lens epithelial cells.
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Affiliation(s)
- W P Leenders
- Department of Molecular Biology and Cell Biology, University of Nijmegen, The Netherlands
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Brunekreef GA, Kraft HJ, Schoenmakers JG, Lubsen NH. The mechanism of recruitment of the lactate dehydrogenase-B/epsilon-crystallin gene by the duck lens. J Mol Biol 1996; 262:629-39. [PMID: 8876643 DOI: 10.1006/jmbi.1996.0541] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In duck, the housekeeping enzyme lactate dehydrogenase B (LDH-B) and the lens structural protein epsilon-crystallin are encoded by the same single copy gene. Transcription of the gene is initiated from two closely spaced start sites, at -28 and +1. The usage of the downstream site is greatly enhanced in lens. Deletion mapping of the promoter shows that the region -70/+18 specifies the enhanced promoter activity in the lens. A critical role is played by the consensus Sp1 binding site at -50; mutation of this site abolishes lens-preferred expression. Deletion of the +1 transcription initiation site also leads to a decrease in lens-preferred expression, which can be restored by moving the -28 transcription initiation site downstream. By band shift experiments, supershift mobility assays and methylation interference assays, Sp1 was shown to bind to the Sp1 consensus binding site at -50 using either heart or lens nuclear extracts. Co-expression of Sp1 or Sp1-like factors inhibited the activity of an LDH-B/epsilon-crystallin promoter construct by approximately 60% in lens and by 40% in heart cells. Co-expression of Pax-6, a transcription factor shown to be involved in the lens-enhanced expression of a number of other crystallin genes, did not influence the promoter activity of the -130/+650 LDH-B/epsilon-crystallin promoter construct. In contrast to other crystallin promoters, the LDH-B/epsilon-crystallin promoter does not appear to contain a lens-specific element, rather our data lead to a model in which a factor transmitting the effect of Sp1, bound at -50, to the transcription initiation complex is responsible for the lens-preferred expression of the LDH-B/epsilon-crystallin promoter.
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Affiliation(s)
- G A Brunekreef
- Department of Molecular Biology and Cell Biology, University of Nijmegen, The Netherlands
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Dirks RP, Kraft HJ, Van Genesen ST, Klok EJ, Pfundt R, Schoenmakers JG, Lubsen NH. The cooperation between two silencers creates an enhancer element that controls both the lens-preferred and the differentiation stage-specific expression of the rat beta B2-crystallin gene. Eur J Biochem 1996; 239:23-32. [PMID: 8706714 DOI: 10.1111/j.1432-1033.1996.0023u.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The rat beta B2-crystallin gene is active only during a specific stage of the differentiation of rat lens fibre cells directed by basic fibroblast growth factor. The regulatory elements that determine the transient activity of this gene are located in the -750/-123 region and in the first intron. Singly, these elements act as silencers, together they constitute an enhancer that is active only during the specific differentiation stage. An additional silencer is found between -123 and -77. The proximal promoter region contains a Pax-6 binding site at -65/-51. In vitro, binding to this site could be detected but, according to in vivo footprinting experiments, this site is not occupied in the endogenous gene. Furthermore, co-expression of Pax-6 did not enhance promoter activity. Finally, mutation or deletion of this site did not affect promoter activity: the region -37/+10 sufficed for basal promoter activity. The cooperation between the -750/ -123 region and the first intron of the beta B2-crystallin gene not only determines the differentiation stage-specific activity of the gene, but also contributes to the highly increased expression in lens cells compared with non-lens cells.
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Affiliation(s)
- R P Dirks
- Department of Molecular Biology, University of Nijmegen, The Netherlands
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