Project description:A core evolutionary function of the p53 family is to protect the genomic integrity of gametes. However, the role of p73 in the male germ line is unknown. Here, we reveal that TAp73 unexpectedly functions as an adhesion and maturation factor of the seminiferous epithelium orchestrating spermiogenesis. TAp73 knockout (TAp73KO) and p73KO mice, but not ?Np73KO mice, display a "near-empty seminiferous tubule" phenotype due to massive premature loss of immature germ cells. The cellular basis of this phenotype is defective cell-cell adhesions of developing germ cells to Sertoli nurse cells, with likely secondary degeneration of Sertoli cells, including the blood-testis barrier, which leads to disruption of the adhesive integrity and maturation of the germ epithelium. At the molecular level, TAp73, which is produced in germ cells, controls a coordinated transcriptional program of adhesion- and migration-related proteins including peptidase inhibitors, proteases, receptors, and integrins required for germ-Sertoli cell adhesion and dynamic junctional restructuring. Thus, we propose the testis as a unique organ with strict division of labor among all family members: p63 and p53 safeguard germ line fidelity, whereas TAp73 ensures fertility by enabling sperm maturation.
Project description:A core evolutionary function of the p53 family is to protect the genomic integrity of gametes. However, the role of p73 in the male germline is unknown. Here we uncover that TAp73 unexpectedly functions as adhesion and maturation factor of the seminiferous epithelium orchestrating spermiogenesis. TAp73KO and p73KO mice, but not M-NM-^TNp73KO mice, display a M-bM-^@M-^Xnear-empty seminiferous tubuleM-bM-^@M-^Y phenotype due to massive premature loss of immature germ cells. Its cellular basis are defective cell-cell adhesions of developing germ cells to Sertoli nurse cells, with secondary degeneration of Sertoli cells including the blood-testis-barrier, thereby disrupting the adhesive integrity and maturation of the germ epithelium. At the molecular level, TAp73, produced in germ cells, controls a coordinated transcriptional program of adhesion- and migration-related proteins including peptidase inhibitors, proteases, receptors and integrins required for germ-Sertoli cell adhesion and dynamic junctional restructuring. Thus, the testis emerges as unique organ with strict division of labor among all family members: p63 and p53 safeguard germline fidelity, while TAp73 ensures fertility by enabling sperm maturation. 3 mice each for control wildtype and TAp73 knockout mice
Project description:A core evolutionary function of the p53 family is to protect the genomic integrity of gametes. However, the role of p73 in the male germline is unknown. Here we uncover that TAp73 unexpectedly functions as adhesion and maturation factor of the seminiferous epithelium orchestrating spermiogenesis. TAp73KO and p73KO mice, but not ΔNp73KO mice, display a ‘near-empty seminiferous tubule’ phenotype due to massive premature loss of immature germ cells. Its cellular basis are defective cell-cell adhesions of developing germ cells to Sertoli nurse cells, with secondary degeneration of Sertoli cells including the blood-testis-barrier, thereby disrupting the adhesive integrity and maturation of the germ epithelium. At the molecular level, TAp73, produced in germ cells, controls a coordinated transcriptional program of adhesion- and migration-related proteins including peptidase inhibitors, proteases, receptors and integrins required for germ-Sertoli cell adhesion and dynamic junctional restructuring. Thus, the testis emerges as unique organ with strict division of labor among all family members: p63 and p53 safeguard germline fidelity, while TAp73 ensures fertility by enabling sperm maturation.
Project description:A core evolutionary function of the p53 family is to protect the genomic integrity of gametes. However, the role of p73 in the male germline is unknown. Here we uncover that TAp73 unexpectedly functions as adhesion and maturation factor of the seminiferous epithelium orchestrating spermiogenesis. TAp73KO and p73KO mice, but not M-NM-^TNp73KO mice, display a M-bM-^@M-^Xnear-empty seminiferous tubuleM-bM-^@M-^Y phenotype due to massive premature loss of immature germ cells. Its cellular basis are defective cell-cell adhesions of developing germ cells to Sertoli nurse cells, with secondary degeneration of Sertoli cells including the blood-testis-barrier, thereby disrupting the adhesive integrity and maturation of the germ epithelium. At the molecular level, TAp73, produced in germ cells, controls a coordinated transcriptional program of adhesion- and migration-related proteins including peptidase inhibitors, proteases, receptors and integrins required for germ-Sertoli cell adhesion and dynamic junctional restructuring. Thus, the testis emerges as unique organ with strict division of labor among all family members: p63 and p53 safeguard germline fidelity, while TAp73 ensures fertility by enabling sperm maturation. 3 mice each for control wildtype and TAp73 knockout mice.
Project description:A core evolutionary function of the p53 family is to protect the genomic integrity of gametes. However, the role of p73 in the male germline is unknown. Here we uncover that TAp73 unexpectedly functions as adhesion and maturation factor of the seminiferous epithelium orchestrating spermiogenesis. TAp73KO and p73KO mice, but not ΔNp73KO mice, display a ‘near-empty seminiferous tubule’ phenotype due to massive premature loss of immature germ cells. Its cellular basis are defective cell-cell adhesions of developing germ cells to Sertoli nurse cells, with secondary degeneration of Sertoli cells including the blood-testis-barrier, thereby disrupting the adhesive integrity and maturation of the germ epithelium. At the molecular level, TAp73, produced in germ cells, controls a coordinated transcriptional program of adhesion- and migration-related proteins including peptidase inhibitors, proteases, receptors and integrins required for germ-Sertoli cell adhesion and dynamic junctional restructuring. Thus, the testis emerges as unique organ with strict division of labor among all family members: p63 and p53 safeguard germline fidelity, while TAp73 ensures fertility by enabling sperm maturation.
Project description:The final stages in mammalian cytokinesis are poorly understood. Previously, we reported that the ADP-ribosyltransferase activity of Pseudomonas aeruginosa type III secreted toxin ExoT inhibits late stages of cytokinesis. Given that Crk adaptor proteins are the major substrates of ExoT ADP-ribosyltransferase activity, we tested the involvement of Crk in cytokinesis. We report that the focal adhesion-associated proteins, Crk and paxillin are essential for completion of cytokinesis. When their function is absent, the cytoplasmic bridge fails to resolve and the daughter cells fuse to form a binucleated cell. During cytokinesis, Crk is required for syntaxin-2 recruitment to the midbody, while paxillin is required for both Crk and syntaxin-2 localization to this compartment. Our data demonstrate that the subcellular localization and the activity of RhoA and citron K, which are essential for early stages of cytokinesis, are not dependent on paxillin, Crk or syntaxin-2. These studies reveal a novel role for Crk and paxillin in cytokinesis and suggest that focal adhesion complex, as a unit, may partake in this fundamental cellular process.
Project description:?-Actinins (ACTNs) are known to crosslink actin filaments at focal adhesions in migrating cells. Among the four isoforms of mammalian ACTNs, ACTN1 and ACTN4 are ubiquitously expressed. Recently, ACTN4 was reported to enhance cancer cell motility, invasion, and metastasis. However, the mechanism by which ACTN4 drives these malignant phenotypes remains unclear. Here, we show that ACTN4, but not ACTN1, induces the formation of immature focal adhesions in DLD-1 cells, leading to the rapid turnover of focal adhesions. Interestingly, zyxin (ZYX) assembly to focal adhesions was markedly decreased in ACTN4-expressing DLD-1 cells, while the recruitment of paxillin (PAX) occurred normally. On the other hand, in ACTN1-expressing DLD-1 cells, PAX and ZYX were normally recruited to focal adhesions, suggesting that ACTN4 specifically impairs focal adhesion maturation by inhibiting the recruitment of ZYX to focal complexes. Using purified recombinant proteins, we found that ZYX binding to ACTN4 was defective under conditions where ZYX binding to ACTN1 was observed. Furthermore, Matrigel invasion of SW480 cells that express high endogenous levels of ACTN4 protein was inhibited by ectopic expression of ACTN1. Altogether, our results suggest that ZYX defective binding to ACTN4, which occupies focal adhesions instead of ACTN1, induces the formation of immature focal adhesions, resulting in the enhancement of cell motility and invasion.
Project description:This work evaluates the response of human aortic endothelial cells (HAECs) to thromboresistant collagen-mimetic hydrogel coatings toward improving the biocompatibility of existing "off-the-shelf" small-caliber vascular grafts. Specifically, bioactive hydrogels - previously shown to support α1/α2 integrin-mediated cell adhesion but to resist platelet activation - were fabricated by combining poly(ethylene glycol) (PEG) with a 120 kDa, triple-helical collagen-mimetic protein(Scl2-2) containing the GFPGER adhesion sequence. Analysis of HAECs seeded onto the resulting PEG-Scl2-2 hydrogels demonstrated that HAEC adhesion increased with increasing Scl2-2 concentration, while HAEC migration rate decreased over this same concentration range. In addition, evaluation of HAEC phenotype at confluence indicated significant differences in the gene expression of NOS3, thrombomodulin, and E-selectin on the PEG-Scl2-2 hydrogels relative to PEG-collagen controls. At the protein level, however, only NOS3 was significantly different between the PEG-Scl2-2 and PEG-collagen surfaces. Furthermore, PECAM-1 and VE-cadherin expression on PEG-Scl2-2 hydrogels versus PEG-collagen controls could not be distinguished at either the gene or protein level. Cumulatively, these data indicate the PEG-Scl2-2 hydrogels warrant further investigation as "off-the-shelf" graft coatings. In future studies, the Scl2-2 protein can potentially be modified to include additional extracellular matrix or cytokine binding sites to further improve endothelial cell responses.
Project description:Mammalian male fertility relies on complex inter- and intracellular signaling during spermatogenesis. Here we describe three alleles of the widely expressed A-kinase anchoring protein 9 (Akap9) gene, all of which cause gametogenic failure and infertility in the absence of marked somatic phenotypes. Akap9 disruption does not affect spindle nucleation or progression of prophase I of meiosis but does inhibit maturation of Sertoli cells, which continue to express the immaturity markers anti-Mullerian hormone and thyroid hormone receptor alpha in adults and fail to express the maturation marker p27(Kip1). Furthermore, gap and tight junctions essential for blood-testis barrier (BTB) organization are disrupted. Connexin43 (Cx43) and zona occludens-1 are improperly localized in Akap9 mutant testes, and Cx43 fails to compartmentalize germ cells near the BTB. These results identify and support a novel reproductive tissue-specific role for Akap9 in the coordinated regulation of Sertoli cells in the testis.