Targeted Expression of a Protease-resistant IGFBP-4 Mutant in Smooth Muscle of Transgenic Mice Results in IGFBP-4 Stabilization and Smooth Muscle Hypotrophy

Zhang, Mingyu; Smith, Eric P.; Kuroda, Hiroyuki; Banach, W; Chernausek, Steven D.; Fagin, James A.

doi:10.1074/jbc.m112082200

Cited by 46 publications

(40 citation statements)

References 47 publications

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“…Transgenic mice overexpressing IGFBP-4 selectively in smooth muscle cells exhibited smooth muscle hypoplasia (Wang et al 1998), which was in direct contrast to the smooth muscle hypertrophy induced by IGF-I overexpression (Wang et al 1997). Moreover, a protease-resistant IGFBP-4 had more potency (Zhang et al 2002), and IGF-I/IGFBP-4 double transgenic mice showed a reduction in wet weight of selected smooth muscle tissues (Wang et al 1998), suggesting that these inhibitory effects of IGFBP-4 are IGF-I dependent.…”

Section: Introductionmentioning

confidence: 88%

Insulin-like growth factor-binding protein-4 inhibits growth of the thymus in transgenic mice

Zhou¹,

Flaswinkel²,

Schneider³

et al. 2004

Journal of Molecular Endocrinology

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Numerous in vitro studies have demonstrated that IGF-binding protein (IGFBP)-4 is a consistent inhibitor of IGF actions. In order to investigate the functions of IGFBP-4 in vivo, transgenic mice were generated by microinjection of a transgene, in which the murine Igfbp4 cDNA is driven by the H-2K b promoter, and followed by a splicing cassette and polyadenylation signal of the human -globin gene. Transgene mRNA was expressed ubiquitously, and elevated IGFBP-4 protein was detected in the spleen, thymus, kidney and lung of transgenic mice. The activities of serum IGFBPs were not changed in transgenic mice. Immunohistochemical studies revealed transgene expression predominantly in the thymic medulla and red pulp of the spleen. Body weight and the weights of the spleen, kidney and lung of transgenic mice were not different from controls. In contrast, the thymus of transgenic mice showed a significantly reduced weight and cortex volume. In transgenic thymus and spleen, cell proliferation was inhibited and apoptosis was stimulated. Transgenic mice showed normal T-and B-cell development and normal basal plasma immunoglobulin levels. In conclusion, overexpression of IGFBP-4 inhibits growth of the thymus. IGFBP-4 excess inhibits cell proliferation and stimulates apoptosis in lymphoid tissues, but does not affect lymphocyte development. These findings suggest that IGFBP-4 is a potential growth inhibitor of lymphoid tissues.

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Section: Introductionmentioning

confidence: 88%

Insulin-like growth factor-binding protein-4 inhibits growth of the thymus in transgenic mice

Zhou¹,

Flaswinkel²,

Schneider³

et al. 2004

Journal of Molecular Endocrinology

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“…The protease-resistant IGFBP4 clone used (dBP4) was previously shown to be resistant to cleavage by a smooth muscle cell-derived protease, but its binding affinity for IGF1 was equivalent to wild-type IGFBP4 (Zhang et al, 2002). Previous studies had demonstrated that this dBP4 construct was resistant to cleavage by a protease present in conditioned medium from smooth muscle cells, but did not unequivocally show that the protease was PAPP-A (Zhang et al, 2002). We demonstrated that this construct was resistant to cleavage by recombinant PAPP-A.…”

Section: Discussionmentioning

confidence: 99%

“…In dBP4, the PAPP-A cleavage site of IGFBP4, KHMAKVRDRSKMK, was mutated to AAMAAVADASAMA, preventing proteolytic cleavage without affecting IGF-binding capacity (Zhang et al, 2002). BP-4 and dBP-4 were excised with EcoRI, ligated into pCMVScript and verified by sequencing.…”

Section: Igfbp4 Cloningmentioning

confidence: 99%

Expression of a protease-resistant insulin-like growth factor-binding protein-4 inhibits tumour growth in a murine model of breast cancer

et al. 2009

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BACKGROUND: Insulin-like growth factor 1 (IGF1) promotes breast cancer and disease progression. Bioavailability of IGF1 is modulated by IGF-binding proteins (IGFBPs). IGFBP4 inhibits IGF1 activity but cleavage by pregnancy-associated plasma protein-A (PAPP-A) protease releases active IGF1. METHODS: Expression of IGF pathway components and PAPP-A was assessed by western blot or RT -PCR. IGFBP4 (dBP4) resistant to PAPP-A cleavage, but retaining IGF-binding capacity, was used to block IGF activity in vivo. 4T1.2 mouse mammary adenocarcinoma cells transfected with empty vector, vector expressing wild-type IGFBP4 or vector expressing dBP4 were implanted in the mammary fat pad of BALB/c mice and tumour growth was assessed. Tumour angiogenesis and endothelial cell apoptosis were assessed by immunohistochemistry. RESULTS: 4T1.2 cells expressed the IGF1R receptor and IGFBP4. PAPP-A was expressed within mammary tumours but not by 4T1.2 cells. Proliferation and vascular endothelial growth factor (VEGF) production by 4T1.2 cells was increased by IGF1(E3R) (recombinant IGF1 resistant to binding by IGFBPs) but not by wild-type IGF1. IGF1-stimulated microvascular endothelial cell proliferation was blocked by recombinant IGFBP4. 4T1.2 tumours expressing dBP4 grew significantly more slowly than controls or tumours expressing wild-type IGFBP4. Inhibition of tumour growth by dBP4 was accompanied by the increased endothelial cell apoptosis. CONCLUSION: Protease-resistant IGFBP4 blocks IGF activity, tumour growth and angiogenesis .

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“…The mouse SMAA promoter directed tissuespecific expression in all mammalian species thus far studied. [19][20][21][22][23][24][25][26] The purpose of this study was to evaluate the ability of this new construct to restore erectile function in an aging rat model of erectile dysfunction and to compare the results so obtained with that of our current construct, pVAX-hSlo. If the duration of action and efficacy are similar to preclinical studies with pVAXhSlo and pcDNA-hSlo, then the use of pSMAA-hSlo may confer additional therapeutic and regulatory advantages, namely, enhancement of the safety profile of Slo gene transfer by limiting its action to smooth muscle cells only.…”

Section: Introductionmentioning

confidence: 99%

Gene transfer with a vector expressing Maxi-K from a smooth muscle-specific promoter restores erectile function in the aging rat

et al. 2008

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Previous reports have demonstrated that gene transfer with the a, or pore-forming, subunit of the human Maxi-K channel (hSlo) restores the decline in erectile capacity observed in established rat models of diabetes and aging. Preliminary data from a human clinical trial also showed safety and potential efficacy in 11 men treated with the same plasmid construct expressing the Maxi-K channel. In all instances, the original plasmid was driven by the heterologous cytomegalovirus promoter which is broadly active in a wide variety of cell and tissue types. To more precisely determine the contribution of the corporal myocyte to the observed physiological effects in vivo, we report here our initial work using a distinct vector (pSMAA-hSlo) in which hSlo gene expression was driven off the mouse smooth muscle a-actin (SMAA) promoter. Specifically, older rats, with diminished erectile capacity, were given a single intracorporal injection with either 100 mg pVAX-hSlo or 10, 100 or 1000 mg pSMAA-hSlo, or vector or vehicle alone. Significantly increased intracavernous pressure (ICP) responses to cavernous nerve stimulation were observed for all doses of both plasmids encoding hSlo, relative to control injections. These data confirm and extend previous observations to document that smooth muscle cell-specific expression of hSlo in corporal tissue is both necessary and sufficient to restore erectile function in aging rats.

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Targeted Expression of a Protease-resistant IGFBP-4 Mutant in Smooth Muscle of Transgenic Mice Results in IGFBP-4 Stabilization and Smooth Muscle Hypotrophy

Cited by 46 publications

References 47 publications

Insulin-like growth factor-binding protein-4 inhibits growth of the thymus in transgenic mice

Insulin-like growth factor-binding protein-4 inhibits growth of the thymus in transgenic mice

Expression of a protease-resistant insulin-like growth factor-binding protein-4 inhibits tumour growth in a murine model of breast cancer

Gene transfer with a vector expressing Maxi-K from a smooth muscle-specific promoter restores erectile function in the aging rat

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