Elevated Protein Kinase A Activity in Stomach Mesenchyme Disrupts Mesenchymal-epithelial Crosstalk and Induces Preneoplasia.

Background & Aims: Mesenchymal-epithelial crosstalk (MEC) in the stomach is executed by pathways such as bone morphogenetic protein (BMP) and extracellular signal-regulated kinase (ERK). Mis-regulation of MEC disrupts gastric homeostasis and causes tumorigenesis. Protein Kinase A (PKA) crosstalks with BMP and ERK signaling; however, PKA function(s) in stomach development and homeostasis remains undefined.

Molecular characterization of nephron progenitors and their early epithelial derivative structures in the nephrogenic zone of the canine fetal kidney.

Nephron progenitors (NPs) and nephrogenesis have been extensively studied in mice and humans and have provided insights into the mechanisms of renal development, disease and possibility of NP-based therapies. However, molecular features of NPs and their derivatives in the canine fetal kidney (CFK) remain unknown. This study was focused to characterize the expression of potential markers of canine NPs and their derivatives by immuno-fluorescence and western blot analysis.

Loss of peri-Wolffian duct stromal Frs2α expression in mice leads to abnormal ureteric bud induction and vesicoureteral reflux.

Unlabelled: BackgroundFibroblast growth factor receptor 2 (Fgfr2) deletion from murine peri-Wolffian duct stroma (ST) results in aberrant ureteric bud induction, abnormal ureteral insertion into the bladder, and high rates of vesicoureteral reflux (VUR). It is unclear which receptor docking protein(s) is/are responsible for Fgfr2 actions in these tissues. We investigated whether the docking protein, fibroblast receptor substrate 2α (Frs2α), had a role in peri-Wolffian duct ST similar to Fgfr2.

Ectopic Phosphorylated Creb Marks Dedifferentiated Proximal Tubules in Cystic Kidney Disease.

Ectopic cAMP signaling is pathologic in polycystic kidney disease; however, its spatiotemporal actions are unclear. We characterized the expression of phosphorylated Creb (p-Creb), a target and mediator of cAMP signaling, in developing and cystic kidney models. We also examined tubule-specific effects of cAMP analogs in cystogenesis in embryonic kidney explants.

Six2creFrs2α knockout mice are a novel model of renal cystogenesis.

Six2cre-mediated deletion of Frs2α (Six2creFrs2αKO), a major fibroblast growth factor receptor (Fgfr) docking protein in mouse nephron progenitors results in perinatal renal hypoplasia; however, postnatal Six2creFrs2αKO kidneys develop cysts. We sought to determine the pathogenesis of Six2creFrs2αKO cyst formation. We performed histological assays, Western blots, and quantitative PCR (qPCR).

Protein Kinase A: A Master Kinase of Granulosa Cell Differentiation.

Activation of protein kinase A (PKA) by follicle stimulating hormone (FSH) transduces the signal that drives differentiation of ovarian granulosa cells (GCs). An unresolved question is whether PKA is sufficient to initiate the complex program of GC responses to FSH. We compared signaling pathways and gene expression profiles of GCs stimulated with FSH or expressing PKA-CQR, a constitutively active mutant of PKA.

The regulation of male fertility by the PTPN11 tyrosine phosphatase.

PTPN11 (also known as SHP2) is a ubiquitously expressed non-receptor tyrosine phosphatase that regulates cell survival, proliferation, differentiation, migration and adhesion. Naturally occurring mutations in the PTPN11 gene cause Noonan and LEOPARD syndromes, two genetic disorders that are characterized by a spectrum of defects including male infertility. This review summarizes four cellular and molecular mechanisms by which PTPN11 acts to support male fertility.

Fibroblast growth factor receptor-Frs2α signaling is critical for nephron progenitors.

Previous studies using transgenic Pax3cre mice have revealed roles for fibroblast growth factor receptors (Fgfrs) and Fgfr substrate 2α (Frs2α) signaling in early metanephric mesenchyme patterning and in ureteric morphogenesis. The role of Fgfr/Frs2α signaling in nephron progenitors is unknown. Thus, we generated mouse models using BAC transgenic Six2EGFPcre (Six2cre) mediated deletion of Fgfrs and/or Frs2α in nephron progenitors.

The transition from stem cell to progenitor spermatogonia and male fertility requires the SHP2 protein tyrosine phosphatase.

SHP2 is a widely expressed protein tyrosine phosphatase required for signal transduction from multiple cell surface receptors. Gain and loss of function SHP2 mutations in humans are known to cause Noonan and LEOPARD syndromes, respectively, that are characterized by numerous pathological conditions including male infertility. Using conditional gene targeting in the mouse, we found that SHP2 is required for maintaining spermatogonial stem cells (SSCs) and the production of germ cells required for male fertility.

Selective ablation of Ppp1cc gene in testicular germ cells causes oligo-teratozoospermia and infertility in mice.

The four isoforms of serine/threonine phosphoprotein phosphatase 1 (PP1), derived from three genes, are among the most conserved proteins known. The Ppp1cc gene encodes two alternatively spliced variants, PP1 gamma1 (PPP1CC1) and PP1 gamma2 (PPP1CC2). Global deletion of the Ppp1cc gene, which causes loss of both isoforms, results in male infertility due to impaired spermatogenesis.

The tyrosine phosphatase SHP2 regulates Sertoli cell junction complexes.

The blood-testis barrier (BTB) is a large junctional complex composed of tight junctions, adherens junctions, and gap junctions between adjacent Sertoli cells in the seminiferous tubules of the testis. Maintenance of the BTB as well as the controlled disruption and reformation of the barrier is essential for spermatogenesis and male fertility. Tyrosine phosphorylation of BTB proteins is known to regulate the integrity of adherens and tight junctions found at the BTB.

Identification of testis 14-3-3 binding proteins by tandem affinity purification.

The 14-3-3 family of proteins interacts with various cellular phosphoproteins and regulates multiple cell signaling cascades. Identification of 14-3-3 interactors is important to define 14-3-3 functions in various biological pathways. The binding partners of protein 14-3-3 in testis are not known.

Regulation of Sertoli-germ cell adhesion and sperm release by FSH and nonclassical testosterone signaling.

Testosterone and FSH act in synergy to produce the factors required to maximize the production of spermatozoa and male fertility. However, the molecular mechanisms by which these hormones support spermatogenesis are not well established. Recently, we identified a nonclassical mechanism of testosterone signaling in cultured rat Sertoli cells.

Proteomic analysis of bovine sperm YWHA binding partners identify proteins involved in signaling and metabolism.

Posttranslational modification of proteins by phosphorylation is involved in regulation of sperm function. Protein phosphatase 1 gamma isoform 2 (PPP1CC_v2) and protein YWHA (also known as 14-3-3) are likely to be key molecules in pathways involving sperm protein phosphorylation. We have shown that phosphorylated PPP1CC_v2 is bound to protein YWHAZ in spermatozoa.

Phosphorylation-dependent interaction of tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein (YWHA) with PADI6 following oocyte maturation in mice.

Proteins in the tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein family (YWHA; also known as 14-3-3) are involved in the regulation of many intracellular processes. We have examined the interaction of YWHA with peptidylarginine deiminase type VI (PADI6), an abundant protein in mammalian oocytes, eggs, and early embryos. Peptidylarginine deiminases catalyze the posttranslational modification of peptidylarginine to citrulline.

Protein phosphatase PP1 gamma 2 in sperm morphogenesis and epididymal initiation of sperm motility.

The serine/threonine phosphatase (PP1) isoform PP1 gamma 2, predominantly expressed in the testis, is a key enzyme in spermatozoa. High PP1 gamma 2 catalytic activity holds motility in check in immature spermatozoa. Inhibition of PP1 gamma 2 causes motility initiation in immature spermatozoa and motility stimulation and changes in flagellar beat parameters in mature spermatozoa.