Differential stability of expression of similarly specified endogenous and exogenous genes in the sea urchin embryo

The object of these experiments was to determine whether competitive titration in vivo of factors required for expression of the CyIIIa·CAT fusion gene would affect expression of the endogenous CyIIIa gene in the same embryos. Earlier work showed that expression of this fusion gene after injection into sea urchin eggs is stoichiometrically reduced when low molar excesses of DNA fragments containing only its regulatory domain are coinjected. In order to compare endogenous (i.e. CyIIIa) and exogenous (i.e. CyIIIa·CAT) expression simultaneously in embryos bearing excess competitor regulatory DNA, we developed, and here describe, a new procedure for generating transgenic sea urchin embryos in which all of the cells in many embryos, and most in others, bear the exogenous DNA. Such large reduction of mosaicism can be achieved by multiple injection of the exogenous DNA fragments into fertilized eggs. Using this method, we demonstrate that at a level of competitor DNA incorporation which reduces CyIIIa·CAT expression by 85%, endogenous CyIIIa mRNA levels are wholly unaffected. Nor is spatial expression of the endogenous CyIIIa gene disturbed. Since the CyIIIa·CAT genes are properly expressed under control of the CyIIIa regulatory sequences, they must participate in the same set of necessary DNA-protein interactions. However, we infer from the results that we report here that the regulatory complexes in the endogenous CyIIIa gene are greatly stabilized relative to those of the exogenous CyIIIa·CAT genes

Monocyte-fibronectin interactions, via a5b_1 integrin, induce expression of CXC chemokine-dependent angiogenic activity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89994/1/white-monocyte-fibronectin_interactions.pd

p38MAPK Induces Cell Surface α(4) Integrin Downregulation to Facilitate erbB-2-Mediated Invasion

We have previously shown that human breast cancer cells that overexpress erbB-2 are growth factor-independent. In order to test the contribution of erbB-2 to this and other transformed phenotypes without the genetic instability of cancer cells, erbB-2 was overexpressed in human mammary epithelial (HME) cells. ErbB-2-overexpressing HME cells exhibit several transformed phenotypes including cell surface α(4) integrin downregulation and invasiveness. We formulated a model for invasiveness that depends on a cell's ability to downregulate α(4) integrin. As small G-proteins play a role in cytoskeleton remodeling and as this is a likely route for α(4) integrin trafficking, we investigated the role of small G-proteins and their downstream signals in mediating α(4) integrin downregulation and invasiveness using Rac 1. Dominant-negative Rac 1 blocked erbB-2-mediated invasion and reversed erbB-2-mediated α(4) integrin downregulation. In addition, constitutively active Rac 1 induced Ó(4) integrin downregulation and invasiveness. In erbB-2-overexpressing and in constitutively active Rac 1-expressing cells, a p38MAP kinase (p38MAPK) inhibitor blocked invasiveness and reversed α(4) integrin downregulation. These data suggest a model in which erbB-2 signaling activates Rac 1, which, in turn, activates p38MAPK, leading to the downregulation of α(4) integrin. These data strengthen the model where loss of α(4) integrin at the cell surface, leading to reduced α(4) integrin binding to plasma fibronectin, plays a role in erbB-2-mediated invasiveness

Suppression of Tumor Recurrence and Metastasis by a Combination of the PHSCN Sequence and the Antiangiogenic Compound Tetrathiomolybdate in Prostate Carcinoma

Plasma fibronectin-mediated invasion of human DU145 prostate cancer cell line was efficaciously inhibited in a rat tumor model by treatment with Ac-PHSCN-NH(2) peptide. Invasion of DU145 cells was stimulated by the PHSRN sequence of plasma fibronectin. However, PHSCN acts as a competitive inhibitor of PHSRN-mediated invasion. In the current study, we determined whether PHSCN could inhibit the recurrence and metastasis of DU145 tumors after excision of the primary tumor in an athymic nude mouse model. We demonstrated that mice treated thrice weekly with intravenous Ac-PHSCN-NH(2) peptide survived tumor-free for more than 30 weeks post-primary tumor excision, whereas their untreated counterparts succumbed to recurrence and/or metastatic disease in significantly less time. Because of the universal requirement for angiogenesis in solid tumor growth, we tested the efficacy of copper deficiency induced by tetrathiomolybdate (TM) to retard tumor growth in the Dunning prostate cancer model. Significant reduction in size of the primary tumor was observed in mice rendered copper deficient. We sought to reduce tumor growth at the primary and metastatic sites by combining the anti-invasion Ac-PHSCN-NH(2) peptide with TM. Improved survival, fewer metastatic lesions, and excellent tolerability were observed with the combination therapy

Integrin a4b1 regulates migration across basement membranes by lung fibroblasts: A role for phosphatase and tensin homologue deleted on chromosome ten

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89988/1/white-integrin_a4b1_regulates.pd