1
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Teng S, Liu G, Li L, Ou J, Yu Y. CUX1 promotes epithelial-mesenchymal transition (EMT) in renal fibrosis of UUO model by targeting MMP7. Biochem Biophys Res Commun 2022; 608:128-134. [PMID: 35397425 DOI: 10.1016/j.bbrc.2022.03.097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 03/18/2022] [Indexed: 11/16/2022]
Abstract
Epithelial-to-mesenchymal transition (EMT) displays a critical role in the development of renal fibrosis, an important pathological process of chronic kidney disease (CKD). Transcription factor Cut-like homeobox 1 (CUX1) has shown profound effects on several kidney diseases. However, its role in CKD has not been understood yet. In this study, unilateral ureteric obstruction (UUO) surgery was performed on male C57BL/6 mice to simulate CKD in vivo. Renal fibrosis was further induced in human proximal tubular epithelial cell (HK-2) by TGF-β1 stimulation. CUX1 and MMP7 were found to be over-expressed in renal tissue of UUO mice. Renal functional analyses and histological assessment indicated that CUX1 knockdown alleviated renal injury in UUO mice. Mitochondrial dysfunction was determined in UUO group and improved after CUX1 silencing. Besides, CUX1 knockdown suppressed EMT in UUO mice and TGF-β1 treated HK-2 cells, as evidenced by reduced expressions of α-SMA, vimentin, fibronectin and augmented abundance of E-cadherin. Furthermore, CUX1 knockdown decreased MMP7 expression by targeting at its promoter region. MMP7 was responsible for the inhibitory effect of CUX1 knockdown on EMT in HK-2 cells. In summary, our findings suggest that CUX1 promotes EMT in CKD by targeting MMP7, and highlight the crucial role of CUX1 in CKD pathogenesis.
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Affiliation(s)
- Siyuan Teng
- Department of Nephrology, The Second Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China.
| | - Ge Liu
- Department of Nephrology, The Second Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Liangjun Li
- Department of Laboratory Medicine, The Second Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Jun Ou
- Department of Nephrology, Affiliated Hospital of Guilin Medical University, Guilin, Guangxi, China
| | - Yang Yu
- Department of Urology, The Second Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
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2
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CUX1 Enhances Pancreatic Cancer Formation by Synergizing with KRAS and Inducing MEK/ERK-Dependent Proliferation. Cancers (Basel) 2021; 13:cancers13102462. [PMID: 34070180 PMCID: PMC8158495 DOI: 10.3390/cancers13102462] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/10/2021] [Accepted: 05/15/2021] [Indexed: 01/19/2023] Open
Abstract
Simple Summary In pancreatic cancer, CUX1 acts as an important mediator of tumor cell proliferation and resistance to apoptosis. Using two different mouse models for the prevalent CUX1 isoforms p200 and p110, we identified p110 CUX1 as the major isoform promoting pancreatic cancer formation in the context of mutant KRAS. We could show an enhanced proliferation by activating and potentiating MEK-ERK signaling via an increased upstream activation of the ADAM17-EGFR axis. This strengthened activation in a KRAS-dependent manner, leading to a dramatically more accelerated formation of invasive PDAC in p110 CUX1 mice within 4 weeks. These results provide the first in vivo evidence for the importance of CUX1 in the development of pancreatic cancer, and highlight CUX1-dependent signaling pathways as potential therapeutic targets. Abstract The transcription factor CUX1 has been implicated in either tumor suppression or progression, depending on the cancer entity and the prevalent CUX1 isoform. Previously, we could show that CUX1 acts as an important mediator of tumor cell proliferation and resistance to apoptosis in pancreatic cancer cell lines. However, in vivo evidence for its impact on pancreatic carcinogenesis, isoform-specific effects and downstream signaling cascades are missing. We crossbred two different CUX1 isoform mouse models (p200 CUX1 and p110 CUX1) with KC (KrasLSL-G12D/+; Ptf1aCre/+) mice, a genetic model for pancreatic precursor lesions (PanIN). In the context of oncogenic KRASs, both mice KCCux1p200 and KCCux1p110 led to increased PanIN formation and development of invasive pancreatic ductal adenocarcinomata (PDAC). In KCCux1p110 mice, tumor development was dramatically more accelerated, leading to formation of invasive PDAC within 4 weeks. In vitro and in vivo, we could show that CUX1 enhanced proliferation by activating MEK-ERK signaling via an upstream increase of ADAM17 protein, which in turn led to an activation of EGFR. Additionally, CUX1 further enhanced MEK-ERK activation through upregulation of the serine/threonine kinase MOS, phosphorylating MEK in a KRAS-independent manner. We identified p110 CUX1 as major driver of pancreatic cancer formation in the context of mutant KRAS. These results provide the first in vivo evidence for the importance of CUX1 in the development of pancreatic cancer, and highlight the importance of CUX1-dependent signaling pathways as potential therapeutic targets.
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3
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Porath B, Livingston S, Andres EL, Petrie AM, Wright JC, Woo AE, Carlton CG, Baybutt R, Vanden Heuvel GB. Cux1 promotes cell proliferation and polycystic kidney disease progression in an ADPKD mouse model. Am J Physiol Renal Physiol 2017; 313:F1050-F1059. [PMID: 28701314 PMCID: PMC5668583 DOI: 10.1152/ajprenal.00380.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 06/20/2017] [Accepted: 07/05/2017] [Indexed: 01/19/2023] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common monogenic hereditary disorders in humans characterized by fluid-filled cysts, primarily in the kidneys. Cux1, a cell cycle regulatory gene highly expressed during kidney development, is elevated in the cyst-lining cells of Pkd1 mutant mice, and in human ADPKD cells. However, forced expression of Cux1 is insufficient to induce cystic disease in transgenic mice or to induce rapid cyst formation after cilia disruption in the kidneys of adult mice. Here we report a double mutant mouse model that has a conditional deletion of the Pkd1 gene in the renal collecting ducts together with a targeted mutation in the Cux1 gene (Pkd1CD;Cux1tm2Ejn). While kidneys isolated from newborn Pkd1CD mice exhibit cortical and medullary cysts, kidneys isolated from newborn Pkd1CD;Cux1tm2Ejn-/- mice did not show any cysts. Because Cux1tm2Ejn-/- are perinatal lethal, we evaluated Pkd1CD mice that were heterozygote for the Cux1 mutation. Similar to the newborn Pkd1CD;Cux1tm2Ejn-/- mice, newborn Pkd1CD;Cux1tm2Ejn+/- mice did not show any cysts. Comparison of Pkd1CD and Pkd1CD;Cux1tm2Ejn+/- mice at later stages of development showed a reduction in the severity of PKD in the Pkd1CD;Cux1tm2Ejn+/- mice. Moreover, we observed an increase in expression of the cyclin kinase inhibitor p27, a target of Cux1 repression, in the rescued collecting ducts. Taken together, our results suggest that Cux1 expression in PKD is not directly involved in cystogenesis but promotes cell proliferation required for expansion of existing cysts, primarily by repression of p27.
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Affiliation(s)
- Binu Porath
- Division of Nephrology and Hypertension, Department of Medicine, Mayo Clinic, Rochester, Minnesota
| | | | - Erica L Andres
- Department of Biology, Wheaton College, Wheaton, Illinois
| | | | | | - Anna E Woo
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Carol G Carlton
- Department of Anatomy and Cell Biology, University of Kansas School of Medicine, Kansas City, Kansas
| | - Richard Baybutt
- Department of Applied Health Sciences, Wheaton College, Wheaton, Illinois; and
| | - Gregory B Vanden Heuvel
- Department of Biology, Wheaton College, Wheaton, Illinois;
- Department of Biomedical Sciences, Western Michigan University Homer Stryker M.D. School of Medicine, Kalamazoo, Michigan
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4
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Ramdzan ZM, Pal R, Kaur S, Leduy L, Bérubé G, Davoudi S, Vadnais C, Nepveu A. The function of CUX1 in oxidative DNA damage repair is needed to prevent premature senescence of mouse embryo fibroblasts. Oncotarget 2016; 6:3613-26. [PMID: 25682875 PMCID: PMC4414141 DOI: 10.18632/oncotarget.2919] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 12/11/2014] [Indexed: 12/19/2022] Open
Abstract
Despite having long telomeres, mouse embryo fibroblasts (MEFs) senesce more rapidly than human diploid fibroblasts because of the accumulation of oxidative DNA damage. The CUX1 homeodomain protein was recently found to prevent senescence in RAS-driven cancer cells that produce elevated levels of reactive-oxygen species. Here we show that Cux1-/- MEFs are unable to proliferate in atmospheric (20%) oxygen although they can proliferate normally in physiological (3%) oxygen levels. CUX1 contains three domains called Cut repeats. Structure/function analysis established that a single Cut repeat domain can stimulate the DNA binding, Schiff-base formation, glycosylase and AP-lyase activities of 8-oxoguanine DNA glycosylase 1, OGG1. Strikingly and in contrast to previous reports, OGG1 exhibits efficient AP-lyase activity in the presence of a Cut repeat. Repair of oxidative DNA damage and proliferation in 20% oxygen were both rescued in Cux1-/- MEFs by ectopic expression of CUX1 or of a recombinant Cut repeat protein that stimulates OGG1 but is devoid of transcription activation potential. These findings reinforce the causal link between oxidative DNA damage and cellular senescence and suggest that the role of CUX1 as an accessory factor in DNA repair will be critical in physiological situations that generate higher levels of reactive oxygen species.
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Affiliation(s)
- Zubaidah M Ramdzan
- Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Ranjana Pal
- Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada.,Department of Biological Sciences, Presidency University, Kolkata 700073, India
| | - Simran Kaur
- Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Lam Leduy
- Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Ginette Bérubé
- Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Sayeh Davoudi
- Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Charles Vadnais
- Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Alain Nepveu
- Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec H3A 1A3, Canada.,Department of Medicine, McGill University, Montreal, Quebec H3A 1A3, Canada.,Department of Oncology, McGill University, Montreal, Quebec H3A 1A3, Canada
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5
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Ramdzan ZM, Nepveu A. CUX1, a haploinsufficient tumour suppressor gene overexpressed in advanced cancers. Nat Rev Cancer 2014; 14:673-82. [PMID: 25190083 DOI: 10.1038/nrc3805] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
CUT-like homeobox 1 (CUX1) is a homeobox gene that is implicated in both tumour suppression and progression. The accumulated evidence supports a model of haploinsufficiency whereby reduced CUX1 expression promotes tumour development. Paradoxically, increased CUX1 expression is associated with tumour progression, and ectopic CUX1 expression in transgenic mice increases tumour burden in several tissues. One CUX1 isoform functions as an ancillary factor in base excision repair and the other CUX1 isoforms act as transcriptional activators or repressors. Several transcriptional targets and cellular functions of CUX1 affect tumorigenesis; however, we have yet to develop a mechanistic framework to reconcile the opposite roles of CUX1 in cancer protection and progression.
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Affiliation(s)
- Zubaidah M Ramdzan
- Goodman Cancer Centre, McGill University, 1160 Pine Avenue West, Montreal, Quebec, H3A 1A3, Canada
| | - Alain Nepveu
- 1] Goodman Cancer Centre, McGill University, 1160 Pine Avenue West, Montreal, Quebec, H3A 1A3, Canada. [2] Department of Biochemistry, McGill University, 1160 Pine Avenue West, Montreal, Quebec, H3A 1A3, Canada. [3] Department of Medicine, McGill University, 1160 Pine Avenue West, Montreal, Quebec, H3A 1A3, Canada. [4] Department of Oncology, McGill University, 1160 Pine Avenue West, Montreal, Quebec, H3A 1A3, Canada
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6
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Vadnais C, Awan AA, Harada R, Clermont PL, Leduy L, Bérubé G, Nepveu A. Long-range transcriptional regulation by the p110 CUX1 homeodomain protein on the ENCODE array. BMC Genomics 2013; 14:258. [PMID: 23590133 PMCID: PMC3770232 DOI: 10.1186/1471-2164-14-258] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 03/26/2013] [Indexed: 01/19/2023] Open
Abstract
Background Overexpression of the Cut homeobox 1 gene, CUX1, inversely
correlates with patient survival in breast cancers. Cell-based assays and
molecular studies have revealed that transcriptional regulation by
CUX1 involves mostly the proteolytically processed p110
isoform. As there is no antibody specific to p110 CUX1 only, an alternate
strategy must be employed to identify its targets. Results We expressed physiological levels of a tagged-p110 CUX1 protein and performed
chromatin affinity purification followed by hybridization on ENCODE and
promoter arrays. Targets were validated by chromatin immunoprecipitation and
transcriptional regulation by CUX1 was analyzed in expression profiling and
RT-qPCR assays following CUX1 knockdown or p110 CUX1 overexpression.
Approximately 47% and 14% of CUX1 binding sites were respectively mapped
less than 4 Kbp, or more than 40 Kbp, away from a transcription start site.
More genes exhibited changes in expression following CUX1 knockdown than
p110 CUX1 overexpression. CUX1 directly activated or repressed 7.4% and 8.4%
of putative targets identified on the ENCODE and promoter arrays
respectively. This proportion increased to 11.2% for targets with 2 binding
sites or more. Transcriptional repression was observed in a slightly higher
proportion of target genes. The CUX1 consensus binding motif, ATCRAT, was
found at 47.2% of the CUX1 binding sites, yet only 8.3% of the CUX1
consensus motifs present on the array were bound in vivo. The
presence of a consensus binding motif did not have an impact on whether a
target gene was repressed or activated. Interestingly, the distance between
a binding site and a transcription start site did not significantly reduced
the ability of CUX1 to regulate a target gene. Moreover, CUX1 not only was
able to regulate the next adjacent gene, but also regulated the gene located
beyond this one as well as the gene located further away in the opposite
direction. Conclusion Our results demonstrate that p110 CUX1 can activate or repress transcription
when bound at a distance and can regulate more than one gene on certain
genomic loci.
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Affiliation(s)
- Charles Vadnais
- Goodman Cancer Centre, McGill University, 1160 Pine avenue West, Montreal, Quebec H3A 1A3, Canada
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7
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Vadnais C, Davoudi S, Afshin M, Harada R, Dudley R, Clermont PL, Drobetsky E, Nepveu A. CUX1 transcription factor is required for optimal ATM/ATR-mediated responses to DNA damage. Nucleic Acids Res 2012; 40:4483-95. [PMID: 22319212 PMCID: PMC3378881 DOI: 10.1093/nar/gks041] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The p110 Cut homeobox 1 (CUX1) transcription factor regulates genes involved in DNA replication and chromosome segregation. Using a genome-wide-approach, we now demonstrate that CUX1 also modulates the constitutive expression of DNA damage response genes, including ones encoding ATM and ATR, as well as proteins involved in DNA damage-induced activation of, and signaling through, these kinases. Consistently, RNAi knockdown or genetic inactivation of CUX1 reduced ATM/ATR expression and negatively impacted hallmark protective responses mediated by ATM and ATR following exposure to ionizing radiation (IR) and UV, respectively. Specifically, abrogation of CUX1 strongly reduced ATM autophosphorylation after IR, in turn causing substantial decreases in (i) levels of phospho-Chk2 and p53, (ii) γ-H2AX and Rad51 DNA damage foci and (iii) the efficiency of DNA strand break repair. Similarly remarkable reductions in ATR-dependent responses, including phosphorylation of Chk1 and H2AX, were observed post-UV. Finally, multiple cell cycle checkpoints and clonogenic survival were compromised in CUX1 knockdown cells. Our results indicate that CUX1 regulates a transcriptional program that is necessary to mount an efficient response to mutagenic insult. Thus, CUX1 ensures not only the proper duplication and segregation of the genetic material, but also the preservation of its integrity.
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Affiliation(s)
- Charles Vadnais
- Goodman Cancer Centre, Department of Biochemistry, McGill University, 1160 Pine avenue West, Montreal, Quebec, Canada, H3A 1A3
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8
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Hulea L, Nepveu A. CUX1 transcription factors: from biochemical activities and cell-based assays to mouse models and human diseases. Gene 2012; 497:18-26. [PMID: 22306263 DOI: 10.1016/j.gene.2012.01.039] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 01/09/2012] [Accepted: 01/18/2012] [Indexed: 01/19/2023]
Abstract
ChIP-chip and expression analyses indicated that CUX1 transcription factors regulate a large number of genes and microRNAs involved in multiple cellular processes. Indeed, in proliferating cells CUX1 was shown to regulate several genes involved in DNA replication, progression into S phase and later, the spindle assembly checkpoint that controls progression through mitosis. siRNA-mediated knockdown established that CUX1 is required for cell motility. Moreover, higher expression of short CUX1 isoforms, as observed in many cancers, was shown to stimulate cell migration and invasion. In parallel, elevated expression particularly in higher grade tumors of breast and pancreatic cancers implicated CUX1 in tumor initiation and progression. Indeed, transgenic mouse models demonstrated a causal role of CUX1 in cancers originating from various cell types. These studies revealed that higher CUX1 expression or activity not only stimulates cell proliferation and motility, but also promotes genetic instability. CUX1 has also been implicated in the etiology of polycystic kidney diseases, both from a transgenic approach and the analysis of CUX1 activity in multiple mouse models of this disease. Studies in neurobiology have uncovered a potential implication of CUX1 in cognitive disorders, neurodegeneration and obesity. CUX1 was shown to be expressed specifically in pyramidal neurons of the neocortex upper layers where it regulates dendrite branching, spine development, and synapse formation. In addition, modulation of CUX1 expression in neurons of the hypothalamus has been associated with changes in leptin receptor trafficking in the vicinity of the primary cilium resulting in altered leptin signaling and ultimately, eating behavior. Overall, studies in various fields have allowed the development of several cell-based assays to monitor CUX1 function and have extended the range of organs in which CUX1 plays an important role in development and tissue homeostasis.
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Affiliation(s)
- Laura Hulea
- Goodman Cancer Centre, McGill University, 1160 Pine avenue West, Montreal, Quebec, Canada H3A 1A3
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9
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Kojima K, Takata A, Vadnais C, Otsuka M, Yoshikawa T, Akanuma M, Kondo Y, Kang YJ, Kishikawa T, Kato N, Xie Z, Zhang WJ, Yoshida H, Omata M, Nepveu A, Koike K. MicroRNA122 is a key regulator of α-fetoprotein expression and influences the aggressiveness of hepatocellular carcinoma. Nat Commun 2011; 2:338. [PMID: 21654638 DOI: 10.1038/ncomms1345] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 05/11/2011] [Indexed: 12/18/2022] Open
Abstract
α-fetoprotein (AFP) is not only a widely used biomarker in hepatocellular carcinoma (HCC) surveillance, but is also clinically recognized as linked with aggressive tumour behaviour. Here we show that deregulation of microRNA122, a liver-specific microRNA, is a cause of both AFP elevation and a more biologically aggressive phenotype in HCC. We identify CUX1, a direct target of microRNA122, as a common central mediator of these two effects. Using liver tissues from transgenic mice in which microRNA122 is functionally silenced, an orthotopic xenograft tumour model, and human clinical samples, we further demonstrate that a microRNA122/CUX1/microRNA214/ZBTB20 pathway regulates AFP expression. We also show that the microRNA122/CUX1/RhoA pathway regulates the aggressive characteristics of tumours. We conclude that microRNA122 and associated signalling proteins may represent viable therapeutic targets, and that serum AFP levels in HCC patients may be a surrogate marker for deregulated intracellular microRNA122 signalling pathways in HCC tissues.
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Affiliation(s)
- Kentaro Kojima
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan
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10
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Fragiadaki M, Ikeda T, Witherden A, Mason RM, Abraham D, Bou-Gharios G. High doses of TGF-β potently suppress type I collagen via the transcription factor CUX1. Mol Biol Cell 2011; 22:1836-44. [PMID: 21471005 PMCID: PMC3103400 DOI: 10.1091/mbc.e10-08-0669] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Uncontrolled expression of collagen often leads to tissue scarring and loss of organ function. In this study, we identify a molecular mechanism that may enable us to switch off collagen production when unnecessary (i.e., fibrosis). We conclude that CUX1, which is a CCAAT binding factor displacement protein, may serve as a therapeutic target in treating fibrosis. Transforming growth factor-β (TGF-β) is an inducer of type I collagen, and uncontrolled collagen production leads to tissue scarring and organ failure. Here we hypothesize that uncovering a molecular mechanism that enables us to switch off type I collagen may prove beneficial in treating fibrosis. For the first time, to our knowledge, we provide evidence that CUX1 acts as a negative regulator of TGF-β and potent inhibitor of type I collagen transcription. We show that CUX1, a CCAAT displacement protein, is associated with reduced expression of type I collagen both in vivo and in vitro. We show that enhancing the expression of CUX1 results in effective suppression of type I collagen. We demonstrate that the mechanism by which CUX1 suppresses type I collagen is through interfering with gene transcription. In addition, using an in vivo murine model of aristolochic acid (AA)-induced interstitial fibrosis and human AA nephropathy, we observe that CUX1 expression was significantly reduced in fibrotic tissue when compared to control samples. Moreover, silencing of CUX1 in fibroblasts from kidneys of patients with renal fibrosis resulted in increased type I collagen expression. Furthermore, the abnormal CUX1 expression was restored by addition of TGF-β via the p38 mitogen-activated protein kinase pathway. Collectively, our study demonstrates that modifications of CUX1 expression lead to aberrant expression of type I collagen, which may provide a molecular basis for fibrogenesis.
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Affiliation(s)
- Maria Fragiadaki
- Renal Medicine, Imperial College London, Hammersmith Campus, London W12 ONN, United Kingdom.
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Abstract
OBJECTIVE HIV-associated nephropathy (HIVAN) is characterized by the development of glomerulosclerosis and is associated with glomerular epithelial cell proliferation. It has recently been shown that activation of the Notch signaling pathway in podocytes results in glomerulosclerosis and podocyte proliferation. To determine whether Notch signaling is involved in renal disorder associated with HIVAN, we evaluated the expression of Notch receptors in HIVAN. DESIGN We evaluated the expression of the Notch signaling pathway using an HIV-transgenic (HIV-Tg) rat model of HIVAN, and biopsy samples from HIVAN and normal controls. METHODS Paraffin sections and kidney lysates were used for immunohistochemistry, immunofluorescence and western blot analysis. RESULTS A collapsing variant of glomerulosclerosis and focal segmental sclerosis was observed in HIV-Tg rats. Glomeruli of HIV-Tg rats demonstrated activation of Notch1 and Notch4, as determined by the presence of the intracellular domains. In addition, we observed increased expression of the Notch target protein, hairy enhancer of split homolog-1 in glomeruli of these animals. The expression of the Groucho homolog transducin-like enhancer protein 4, a Notch effector protein, and the homeodomain protein cut homeobox 1 were also significantly increased in glomeruli of HIV-Tg rats, and this was associated with decreased expression of the cyclin kinase inhibitor p27. Intriguingly, renal biopsy samples from HIVAN patients also showed upregulation of cleaved Notch1 and Notch4 in the glomeruli compared with the expression in normal kidneys. CONCLUSION Our results demonstrate activation of Notch signaling pathway in HIVAN, thereby underscoring its role in disease pathogenesis.
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Sun J, Xu Y, Deng H, Sun S, Dai Z, Sun Y. Involvement of osteopontin upregulation on mesangial cells growth and collagen synthesis induced by intermittent high glucose. J Cell Biochem 2010; 109:1210-21. [PMID: 20135641 DOI: 10.1002/jcb.22503] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Glucose fluctuations are strong predictor of diabetic vascular complications. We explored the effects of constant and intermittent high glucose on the proliferation and collagen synthesis of cultured rat mesangial cells. Furthermore, the possible involvement of osteopontin (OPN) was assessed. In rat mesangial cells cultured in 5, 25, or 5 mmol/L alternating with 25 mmol/L glucose in the absence or presence of neutralizing antibodies to OPN, beta3 integrin receptor and beta5 integrin receptor, the cell proliferation, collagen synthesis, and the expression of OPN and type IV collagen were assessed. In cultured mesangial cells, treatment with constant or intermittent high glucose significantly increased [(3)H]thymidine incorporation in a time-dependent manner. A modest increase was observed at 12 h, and further deteriorated afterwards, and reached the maximum incorporation at 48 h. Treatment with constant high glucose for 48 h resulted in significant increases in [(3)H]thymidine incorporation, cell number, [(3)H]proline incorporation, mRNA, and protein levels of type IV collagen and OPN compared with mesangial cells treated with the normal glucose, which were markedly enhanced in cells exposed to intermittent high glucose medium. In addition, neutralizing antibodies to either OPN or its receptor beta3 integrin but not neutralizing antibodies to beta5 integrin can effectively prevented proliferation and collagen synthesis of mesangial cells induced by constant or intermittent high glucose. Intermittent high glucose exacerbates mesangial cells growth and collagen synthesis by upregulation of OPN expression, indicating that glycemic variability have important pathological effects on the development of diabetic nephropathy, which is mediated by the stimulation of OPN expression and synthesis.
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Affiliation(s)
- Jiazhong Sun
- Department of Endocrinology, Zhongnan Hospital, Wuhan University, Wuhan 430071, China.
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13
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Cadieux C, Kedinger V, Yao L, Vadnais C, Drossos M, Paquet M, Nepveu A. Mouse mammary tumor virus p75 and p110 CUX1 transgenic mice develop mammary tumors of various histologic types. Cancer Res 2009; 69:7188-97. [PMID: 19738070 DOI: 10.1158/0008-5472.can-08-4899] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The p75 and p110 isoforms of the CUX1 homeodomain protein are overexpressed in breast tumors and cancer cell lines. To assess and compare the ability of these short CUX1 isoforms in driving mammary tumor development, we used site-specific transgenesis into the Hprt locus to generate transgenic mice expressing p75 or p110 CUX1 under the control of the mouse mammary tumor virus-long terminal repeat. We report that mammary tumors developed after a long latency period, and although various histopathologies were observed, the proportion of adenosquamous carcinomas was significantly higher in p75 CUX1 than in p110 CUX1 transgenic mice. Metastasis to the lung was observed in three p75 CUX1 transgenic mice. Comparisons between tumors and adjacent normal mammary glands revealed that transgenes were overexpressed in most but not all tumors, yet in all cases tested, CUX1 DNA binding was increased, suggesting that both higher expression and changes in post-translational modifications can contribute to stimulate transgene activity. Interestingly, higher expression of erbB2 mRNA was seen in most tumors, not only solid carcinomas but also adenosquamous carcinomas, whereas higher expression of various Wnt genes and activation of the beta-catenin pathway was observed primarily in adenosquamous carcinomas. Activation of erbB2 expression appeared to represent a cooperating event that occurred independently of CUX1. In contrast, chromatin immunoprecipitation, short hairpin RNA-mediated knockdown, and reporter assays established that CUX1 is involved in the transcriptional regulation of several Wnt genes. Together, these results support the notion that oncogenic activity of CUX1 can facilitate the establishment of a Wnt/beta-catenin autocrine loop.
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MESH Headings
- Animals
- Carcinoma, Adenosquamous/genetics
- Carcinoma, Adenosquamous/metabolism
- Carcinoma, Adenosquamous/pathology
- Caseins/biosynthesis
- Caseins/genetics
- Female
- Homeodomain Proteins/biosynthesis
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Humans
- Lung Neoplasms/genetics
- Lung Neoplasms/secondary
- Mammary Neoplasms, Experimental/genetics
- Mammary Neoplasms, Experimental/metabolism
- Mammary Neoplasms, Experimental/pathology
- Mammary Neoplasms, Experimental/virology
- Mammary Tumor Virus, Mouse/genetics
- Mice
- Mice, Transgenic
- Nuclear Proteins/biosynthesis
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Protein Isoforms
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Receptor, ErbB-2/biosynthesis
- Receptor, ErbB-2/genetics
- Receptor, ErbB-2/metabolism
- Repressor Proteins/biosynthesis
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Transcription Factors
- Transgenes
- Wnt Proteins/metabolism
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Affiliation(s)
- Chantal Cadieux
- Goodman Cancer Centre and Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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14
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Alcalay NI, Vanden Heuvel GB. Regulation of cell proliferation and differentiation in the kidney. Front Biosci (Landmark Ed) 2009; 14:4978-91. [PMID: 19482600 DOI: 10.2741/3582] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The mammalian cut proteins are a broadly expressed family of nuclear transcription factors related to the Drosophila protein cut. One member of the cut family, Cux1, has been shown to function as a cell cycle dependent transcription factor, regulating the expression of a number of cell cycle regulatory proteins. Cux1 expression is developmentally regulated in multiple tissues suggesting an important regulatory function. Cux1 exists as multiple isoforms that arise from proteolytic processing of a 200 kD protein or use of an alternate promoter. Several mouse models of Cux1 have been generated that suggest important roles for this gene in cell cycle regulation during hair growth, lung development and maturation, and genitourinary tract development. Moreover, the aberrant expression of Cux1 may contribute to diseases such as polycystic kidney disease and cancer. In this review, we will focus on the phenotypes observed in the five existing transgenic mouse models of Cux1, and discuss the role of Cux1 in kidney development and disease.
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Affiliation(s)
- Neal I Alcalay
- Department of Anatomy, University of Kansas Medical Center, Kansas City, KS 66160, USA
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15
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CUX1/Wnt signaling regulates epithelial mesenchymal transition in EBV infected epithelial cells. Exp Cell Res 2009; 315:1819-31. [PMID: 19361498 DOI: 10.1016/j.yexcr.2009.04.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 03/06/2009] [Accepted: 04/02/2009] [Indexed: 02/07/2023]
Abstract
Idiopathic pulmonary fibrosis (IPF) is a refractory and lethal interstitial lung disease characterized by alveolar epithelial cells apoptosis, fibroblast proliferation and extra-cellular matrix protein deposition. EBV, localised to alveolar epithelial cells of pulmonary fibrosis patients is associated with a poor prognosis. A strategy based on microarray-differential gene expression analysis to identify molecular drivers of EBV-associated lung fibrosis was utilized. Alveolar epithelial cells were infected with EBV to identify genes whose expression was altered following TGFbeta1-mediated lytic phase. EBV lytic reactivation by TGFbeta1 drives a selective alteration in CUX1 variant (a) (NCBI accession number NM_181552) expression, inducing activation of non-canonical Wnt pathway mediators, implicating it in Epithelial Mesenchymal Transition (EMT), the molecular event underpinning scar production in tissue fibrosis. The role of EBV in EMT can be attenuated by antiviral strategies and inhibition of Wnt signaling by using All-Trans Retinoic Acids (ATRA). Activation of non-canonical Wnt signaling pathway by EBV in epithelial cells suggests a novel mechanism of EMT via CUX1 signaling. These data present a framework for further description of the link between infectious agents and fibrosis, a significant disease burden.
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16
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Sharma M, Brantley JG, Vassmer D, Chaturvedi G, Baas J, Vanden Heuvel GB. The homeodomain protein Cux1 interacts with Grg4 to repress p27 kip1 expression during kidney development. Gene 2009; 439:87-94. [PMID: 19332113 DOI: 10.1016/j.gene.2009.03.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 03/13/2009] [Accepted: 03/14/2009] [Indexed: 01/19/2023]
Abstract
The homeodomain protein Cux1 is highly expressed in the nephrogenic zone of the developing kidney where it functions to regulate cell proliferation. Here we show that Cux1 directly interacts with the co-repressor Grg4 (Groucho 4), a known effector of Notch signaling. Promoter reporter based luciferase assays revealed enhanced repression of p27(kip1) promoter activity by Cux1 in the presence of Grg4. Chromatin immunoprecipitation (ChIP) assays demonstrated the direct interaction of Cux1 with p27(kip1) in newborn kidney tissue in vivo. ChIP assays also identified interactions of Cux1, Grg4, HDAC1, and HDAC3 with p27(kip1) at two separate sites in the p27(kip1) promoter. DNAse1 footprinting experiments revealed that Cux1 binds to the p27(kip1) promoter on the sequence containing two Sp1 sites and a CCAAT box approximately 500 bp from the transcriptional start site, and to an AT rich sequence approximately 1.5 kb from the transcriptional start site. Taken together, these results identify Grg4 as an interacting partner for Cux1 and suggest a mechanism of p27(kip1) repression by Cux1 during kidney development.
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Affiliation(s)
- Madhulika Sharma
- Department of Anatomy, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
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17
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18
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Cadieux C, Harada R, Paquet M, Côté O, Trudel M, Nepveu A, Bouchard M. Polycystic kidneys caused by sustained expression of Cux1 isoform p75. J Biol Chem 2008; 283:13817-24. [PMID: 18356167 DOI: 10.1074/jbc.m709332200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The transcriptional regulator Cux1 (CDP, Cutl1) is aberrantly expressed in mouse models for polycystic kidney disease. Here we show that p75-Cux1, the shortest isoform of Cux1, transcribed from an alternative promoter within intron 20, is also deregulated in polycystic kidneys derived from Pkd1 mutant embryos. To determine the role of the p75-Cux1 isoform in cystogenesis, we generated transgenic mice expressing p75-CUX1 in the kidneys and other tissues. Strikingly, these animals developed polycystic kidneys at variable penetrance and severity, correlating with transgene expression levels. Histological and marker analysis of p75-CUX1-derived polycystic kidneys revealed renal cysts derived from the tubular nephron, supporting a model of autosomal dominant polycystic kidney disease. Transgenic p75-CUX1 kidneys additionally showed an up-regulation of the protooncogene c-myc and a down-regulation of the cyclin-dependent kinase inhibitor p27. Chromatin affinity purification experiments confirmed the direct interaction of Cux1 with the c-myc and p27 promoters. These molecular alterations were accompanied by an increase in cilia length and in the proliferative index of epithelial cells lining the cysts. Together, these results identify an important role for the short isoform of CUX1 in polycystic kidney disease development.
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Affiliation(s)
- Chantal Cadieux
- Department of Biochemistry, McGill University, Montreal H3G 1Y6 Canada
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19
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Sansregret L, Nepveu A. The multiple roles of CUX1: insights from mouse models and cell-based assays. Gene 2008; 412:84-94. [PMID: 18313863 DOI: 10.1016/j.gene.2008.01.017] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2007] [Revised: 01/18/2008] [Accepted: 01/21/2008] [Indexed: 01/19/2023]
Abstract
Cux (Cut homeobox) genes are present in all metazoans. Early reports described many phenotypes caused by cut mutations in Drosophila melanogaster. In vertebrates, CUX1 was originally characterized as the CCAAT-displacement protein (CDP). Another line of investigation revealed the presence of CUX1 within a multi-protein complex called the histone nuclear factor D (HiNF-D). Recent studies led to the identification of several CUX1 isoforms with distinct DNA binding and transcriptional properties. While the CCAAT-displacement activity was implicated in the transcriptional repression of several genes, some CUX1 isoforms were found to participate in the transcriptional activation of some genes. The expression and activity of CUX1 was shown to be regulated through the cell cycle and to be a target of TGF-beta signaling. Mechanisms of regulation include alternative transcription initiation, proteolytic processing, phosphorylation and acetylation. Cell-based assays have established a role for CUX1 in the control of cell cycle progression, cell motility and invasion. In the mouse, gene inactivation as well as over-expression in transgenic mice has revealed phenotypes in multiple organs and cell types. While some phenotypes could be explained by the presumed functions of CUX1 in the affected cells, other phenotypes invoked non-cell-autonomous effects that suggest regulatory functions with an impact on cell-cell interactions. The implication of CUX1 in cancer was suggested first from its over-expression in primary tumors and cancer cell lines and was later confirmed in mouse models.
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20
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Sharma M, Fopma A, Brantley JG, Vanden Heuvel GB. Coexpression of Cux-1 and Notch signaling pathway components during kidney development. Dev Dyn 2005; 231:828-38. [PMID: 15499562 DOI: 10.1002/dvdy.20175] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cux-1 is the murine homologue of the Drosophila gene cut, which is required for cellular differentiation in several tissues, including the wing margin and Malpighian tubule. Mammalian cut proteins function as cell cycle-dependent transcriptional repressors in proliferating cells. Targets of Cux-1 repression include the cyclin kinase inhibitors p21 and p27. However, little is known about the regulation of Cux-1. In Drosophila, multiple genetic interactions between Cut and the Notch and Wingless signaling pathways occur during wing development. To begin to determine whether Cux-1 regulation by the Notch signaling pathway is conserved in mammals, we compared the expression patterns of Cux-1, the murine Notch receptors (Notch 1-4), and the murine ligands (Jagged 1, Jagged 2, and Delta 1) during murine embryogenesis and kidney development. In this report, we demonstrate that Cux-1 expression overlaps with that of Notch signaling pathway components in multiple tissues during embryonic development. In the developing kidney, Cux-1 expression overlaps with that of Notch pathway components in the condensing mesenchyme, in pretubular aggregates (comma and S-shaped bodies), and in the presumptive podocytes of capillary loop stage glomeruli. Furthermore, Cux-1 was significantly up-regulated in the rat kidney epithelial cell line RKE expressing a constitutively active Notch 1, and this finding was associated with a reduction of p27. Moreover, Cux-1 interacts with the Groucho homolog TLE-4, a corepressor recruited by Notch effector proteins. Taken together, these results suggest that Cux-1 may function in the context of the Notch signaling pathway in multiple tissues during mammalian embryogenesis.
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Affiliation(s)
- Madhulika Sharma
- Department of Anatomy and Cell Biology, and the Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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21
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Sharma M, Brantley JG, Alcalay NI, Zhou J, Heystek E, Maser RL, Vanden Heuvel GB. Differential expression of Cux-1 and p21 in polycystic kidneys from Pkd1 null and cpk mice. Kidney Int 2005; 67:432-42. [PMID: 15673290 DOI: 10.1111/j.1523-1755.2005.67099.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Cux-1 is a murine homeodomain protein that functions as a cell cycle-dependent transcriptional repressor in proliferating cells. Targets of Cux-1 repression include the cyclin kinase inhibitors p21 and p27. In the kidney, Cux-1 is spatially and temporally regulated, and ectopic expression of Cux-1 in transgenic mice results in renal hyperplasia. Previously, we observed that Cux-1 is deregulated in cystic kidneys from cpk mice. Recent studies have suggested a role for the cyclin kinase inhibitor p21 in the development of polycystic kidney disease (PKD) in mice lacking PKD1. METHODS Since p21 is a target of transcriptional repression by Cux-1, we compared the expression of Cux-1 and p21 in kidneys from Pkd1 null and cpk mice by immunohistochemistry and Western blotting. We also evaluated apoptosis and the expression of the cyclin kinase inhibitor p27 in Pkd1 null and cpk mice by terminal deoxynucleotidal transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL) staining, immunohistochemistry, and Western blotting. RESULTS In both early and late embryonic kidneys from Pkd1 null mice, Cux-1 was highly and ectopically expressed in normal-appearing tubule epithelium, interstitial cells, and in the epithelial cells lining the cysts, where it colocalized with proliferating cell nuclear antigen (PCNA). Increased Cux-1 expression in Pkd1 null kidneys was also associated with a decrease in p27 expression at late stages of cystogenesis. In cpk kidneys, Cux-1 was not up-regulated until late stages of cyst development. Moreover, in contrast to Pkd1 null kidneys, p21 and p27 were highly expressed in cpk kidneys. In late stages of cystogenesis, Cux-1 and p21 colocalized in cyst lining cells, which also showed a high incidence of apoptosis. CONCLUSION These results suggest that cyst development in Pkd1 null mice and cpk mice proceeds through different mechanisms. In Pkd1 null mice, ectopic expression of Cux-1 is associated with increased cell proliferation. In contrast, in cpk mice, ectopic expression of Cux-1 is associated with apoptosis.
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Affiliation(s)
- Madhulika Sharma
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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22
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Gooch JL, Toro JJ, Guler RL, Barnes JL. Calcineurin A-alpha but not A-beta is required for normal kidney development and function. THE AMERICAN JOURNAL OF PATHOLOGY 2004; 165:1755-65. [PMID: 15509543 PMCID: PMC1618665 DOI: 10.1016/s0002-9440(10)63430-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/29/2004] [Indexed: 01/23/2023]
Abstract
Calcineurin is an important signaling molecule in the kidney and may be involved in a variety of processes. The phosphatase subunit of calcineurin (CnA) has three isoforms, alpha, beta, and gamma. In this study, we investigated the effect of loss of calcineurin A-alpha (CnA-alpha) or calcineurin A-beta (CnA-beta) on the development and function of the kidney. Total calcineurin expression and activity was significantly reduced in whole kidney homogenates from both CnA-alpha -/- and CnA-beta -/- mice. Kidneys of CnA-beta -/- mice appear normal and the mice develop with no phenotypic abnormalities. In contrast, kidneys of CnA-alpha -/- animals fail to fully develop. In particular, postnatal maturation of the nephrogenic zone (NZ) is defective. Within the NZ, glomeruli also fail to mature and lack mesangial cells. In addition to alterations in development, there is an absence of proliferation and an increase of cell death in the NZ with loss of CnA-alpha. Finally, increased collagen deposition is observed and serum creatinine levels are significantly increased in CnA-alpha -/- animals compared to wild-type littermates, indicating that kidney function is impaired. In summary, absence of CnA-alpha but not CnA-beta leads to a defect in normal maturation of the NZ and glomeruli, alterations in the cell cycle, and impaired kidney function.
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Affiliation(s)
- Jennifer L Gooch
- Medicine/Nephrology, University of Texas Health Science Center, San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
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23
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Ledford AW, Brantley JG, Kemeny G, Foreman TL, Quaggin SE, Igarashi P, Oberhaus SM, Rodova M, Calvet JP, Heuvel GBV. Deregulated expression of the homeobox gene Cux-1 in transgenic mice results in downregulation of p27(kip1) expression during nephrogenesis, glomerular abnormalities, and multiorgan hyperplasia. Dev Biol 2002; 245:157-71. [PMID: 11969263 PMCID: PMC4454426 DOI: 10.1006/dbio.2002.0636] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Cux-1 is a murine homeobox gene that is highly expressed in the developing kidney with expression restricted to the nephrogenic zone. Cux-1 is highly expressed in cyst epithelium of polycystic kidneys from C57BL/6J-cpk/cpk mice, but not in kidneys isolated from age-matched phenotypically normal littermates. To further elucidate the role of Cux-1 in renal development, we generated transgenic mice expressing Cux-1 under the control of the CMV immediate early gene promoter. Mice constitutively expressing Cux-1 developed multiorgan hyperplasia and organomegaly, but not an overall increase in body size. Transgenic kidneys were enlarged 50% by 6 weeks of age, with the increased growth primarily restricted to the cortex. Proliferating cells were found in proximal and distal tubule epithelium throughout the cortex, and the squamous epithelium that normally lines Bowman's capsule was replaced with proximal tubule epithelium. However, the total number of nephrons was not increased. In the developing kidneys of transgenic mice, Cux-1 was ectopically expressed in more highly differentiated tubules and glomeruli, and this was associated with reduced expression of the cyclin kinase inhibitor, p27. Transient transfection experiments revealed that Cux-1 is an inhibitor of p27 promoter activity. These results suggest that Cux-1 regulates cell proliferation during early nephrogenesis by inhibiting expression of p27.
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Affiliation(s)
- Aric W. Ledford
- Department of Biology, East Carolina University, Greenville, North Carolina 27858
| | - Jennifer G. Brantley
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Gabor Kemeny
- Department of Anatomy and Cell Biology, East Carolina University, Greenville, North Carolina 27858
| | - Tonia L. Foreman
- Department of Anatomy and Cell Biology, East Carolina University, Greenville, North Carolina 27858
| | - Susan E. Quaggin
- §Samuel Lunenfeld Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, Canada M5G 1X5
| | - Peter Igarashi
- Section of Nephrology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Stephanie M. Oberhaus
- ∥Department of Microbiology and Immunology, East Carolina University, Greenville, North Carolina 27858
| | - Marianna Rodova
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - James P. Calvet
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160
| | - Gregory B. Vanden Heuvel
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas 66160
- To whom correspondence should be addressed. Fax: 913-588-2710.
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