Activin–like kinase–3 activity is important for kidney regeneration and reversal of fibrosis

Molecules associated with TGF-β superfamily such as BMPs and TGF-β are key regulators of inflammation, apoptosis and cellular transitions. Here, we demonstrate that the BMP receptor activin–like kinase 3 (Alk3) is elevated early in response to kidney injury and its deletion in the tubular epithelium leads to enhanced TGF-β1 / Smad3 signaling, epithelial damage and fibrosis, suggesting a protective role for Alk3 mediated signaling. Structure–function analysis of Alk3 / BMP / BMPRII ligand–receptor complex coupled with synthetic organic chemistry led us to construct a library of small peptide agonists of BMP signaling that function via Alk3 receptor. One such peptide agonist, THR–123, suppressed inflammation, apoptosis epithelial–to–mesenchymal transition program, and reversed fibrosis in mouse models of acute and chronic injury. Combining THR–123 and angiotensin–converting enzyme inhibitor, captopril, exhibited additive therapeutic benefit in controlling fibrosis. Our studies demonstrate that BMP signaling agonists constitute a new line of therapeutic agents with a potential utility in the clinic to induce regeneration, repair and reverse fibrosis

Follicle-Stimulating Hormone Receptor: Advances and Remaining Challenges

International audienc

The LH/CG and FSH receptors: different molecular forms and intracellular traffic

International audienceMonoclonal antibodies have been raised against the LH/CG receptor [1] and have allowed to perform immunochemical studies of the receptor in target cells. Three different forms of the LH/CG receptor are physiologically expressed: a mature ∼85 kDa transmembrane species corresponding to the full length receptor, a ∼68 kDa high mannose containing species corresponding to a precursor which accumulates inside the cells, and truncated soluble ∼45–48 kDa molecular weight species corresponding to the variant messanger RNAs generated by alternative splicing. Monoclonal antibodies against the human FSH receptor were also prepared. They allow to observe the existence of two forms of the FSH receptor in the ovaries: a major ∼87 kDa species corresponding to the mature receptor and a minor ∼81 kDa species corresponding to a high mannose rich precursor. No variant forms of the receptor corresponding to alternative mRNA transcripts were detected. The transport of hCG was examined in rat testicular microvasculature by electron microscopy and by analyzing the transfer of radiolabeled hormone and antireceptor antibodies. LH/CG receptors were present in endothelial cells and were involved in hormone transcytosis through these cells. Immunocytochemical experiments have shown that the FSH receptor has a polarized expression in the Sertoli cells of the testes whereas the LH/CG receptor is spread on the surface of thecal granulosa and luteal cells in the ovary and Leydig cells in the testes. To study the mechanism of this polarization FSH, LH and TSH receptors were expressed in polarized MDCK cells. The mechanism of basolateral localization and of transcytosis of the receptors was studied using this model. The effect of hormone, cAMP and agents acting on G proteins was examined

Size heterogeneity and specific binding property of immunoreactive prolactin in human seminal plasma

Following gel filtration on a Sephadex G-100 column, and radioimmunoassay of the effluent fractions, seminal plasma samples from fertile men appeared to possess three discrete immunoreactive prolactin (IR-Prl) components analogous to those of normal serum and pituitary extract and an additional minor component which was eluted after ribonuclease. Furthermore, IR-Prl seminal plasma was predominantly recovered from the column in the high molecular size region, while in the serum and pituitary extract much of the activity was coeluted with monomeric hPrl (purified). Rechromatography of IR-Prl components in seminal plasma provided no evidence of the conversion of one component into the other. Examination of these different components of IR-Prl by means of radioreceptor assay (RRA) indicated that the highly retarded component exhibited no RRA activity. The other three components differed in their drgrees of RRA activity

Purification of prolactin binding protein from rat seminal vesicle secretion

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Evidence for the presence of specific prolactin binding protein in rat seminal vesicle fluid

The presence of a specific prolactin binding in rat seminal vesicle fluid has been demonstrated. The binding phenomenon was saturable and pH dependent, the optimum pH being 7.2. The prolactin binding protein (PBP, 1800 × g supernatant) was characterized by a single order affinity binding sites with an association constant (Ka) 1.52 × 10(7) mol-1. The specificity of the prolactin binding was demonstrated by the fact that other proteohormones such as rFSH, rLH, rTSH and hTSH failed to inhibit the binding of labelled hormone to PBP, while unlabelled oPRL gave a dose-response inhibition curve. Among the rats in the age group 45 to 180 days, PBP obtained from animals of 90 day old showed a maximum binding of radioiodinated rPRL. Following castration for five days the percent binding of 125-I-rPRL to PBP decreased markedly. The treatment of castrated rats with testosterone propionate for five days returned the 125-I-rPRL binding to near intact values. Following a centrifugation of 1800 × g supernatant at 360 000 × g for 3 h, prolactin binding activity still remained in the supernatant thus implicating that the binding protein is in a soluble state

Changes in the ratio between serum and "specific" levels of human chorionic gonadotropin in different trimesters of pregnancy

Sixty-one sera from different trimesters of pregnancy were analyzed by two 125-I-NIH-HCG assay systems, employing anti-intact HCG serum and anti θ-HCG serum, respectively. The ratios of the levels measured in the two assay systems changed with the duration of pregnancy. The ratios during trimesters 1,2, and 3 were 2.94, 1.99, and 2.37, respectively. The cross-reactivity of proteohormones other than HCG was tested in both the assay systems. The two assay systems could be comparable in their high degree of specificity. However, the relative affinities of intact HCG and θ-HCG in the two assay systems were observed to be different. It was suggested that the significant differences in the ratios of the levels measured by the tow assay systems might have been infulenced by the occurrence of θ-HCG in serum and that the levels of the subunit must have changed at different stages of pregnancy

Nature of cross-reaction between hCG and anti-oLH serum and development of a radioimmunoassay to measure hLH specifically in the presence of hCG

Immunological cross-reaction between hCG and anti-oLH sera has been demonstrated using radioimmunoassay techniques. The results indicate that this cross-reaction is incomplete and that the anti-oLH sera used have the ability to distinguish between LH and hCG. Following absorption with purified hCG, anti-oLH serum was used to develop a heterologous radioimmunoassay "[125I]iodo-hLH + anti-oLH serum" (H-O, RIA) which specifically and selectively measures hLH in serum samples containing both hLH and hCG. In this radioimmunoassay, hCG and subunits of hCG do not cross-react with hLH, in the range in which these hormones are present in human serum under physiological conditions. Other hormones such as hPL, hPRL, hGH, hFSH, hTSH, and GnRH do not interfere with the measurement of LH by radioimmunoassay. The sensitivity of the assay was 1.5 mlU (25 ng) per ml (LER 907 standard), and the inter- and intra-assay coefficients of variations for samples were 10.83% and 8.4%, respectively. The recoveries of hLH added to pregnancy serum containing an hCG concentration of 8.55 IU\ml were in the range 95-108%. Determination of LH content of human pituitary extracts by H - 0 RIA gave values which were in close agreement with those derived by bioassay (indices of discrimination 0.72-1.12). Serum LH patterns in women during normal menstrual cycles as well as in amenorrheic patients who received GnRH treatment are comparable to those reported by other investigators using other radioimmunoassay systems. Serum samples obtained during the first trimester of pregnancy, when analyzed by H - 0 RIA, showed basal LH levels