Ubiquitin Cross-Reactive Protein is Released by the Bovine Uterus in Response to Interferon during Early Pregnancy1

Abstract

A 16-kDa protein has been identified that is secreted by the bovine endometrium in response to conceptus-derived interferon (IFN)-tau during early pregnancy. Because this uterine protein was similar in size to a human ubiquitin cross-reactive protein (hUCRP) that also was regulated by IFN, we suspected that they might be related. To test this hypothesis, uterine flushings, medium from cultured endometrium, and endometrial tissues were examined for the presence of ubiquitin-immunoreactive proteins. Immunoreacting proteins were detected through use of one-dimensional (1D)-PAGE and Western blotting with ubiquitin and hUCRP antiserum (1:500). A 16-kDa protein that cross-reacted with ubiquitin and hUCRP antisera was released by the endometrium and was present in uterine flushings from all Day 18 pregnant females examined (n = 12). The immunoreacting 16-kDa protein was absent in all nonpregnant females examined (n = 23). Regulation of this uterine protein by recombinant type I IFNs (rbIFN-tau, rbIFN-alpha, and roIFN-tau), using 0, 0.5, 5, and 25 nm of each IFN, was evaluated in nonpregnant (Day 12) heifers (n = 5) using 1D-PAGE and Western blotting. Release of the 16-kDa protein into medium was negligible in controls (0 nm IFN). For each IFN, a dose-dependent increase (p < 0.05) in release of the immunoreacting 16-kDa protein was noted. We conclude that the 16-kDa protein that is produced by the endometrium in response to IFN-tau during early pregnancy also shares epitopes with hUCRP and ubiquitin. The 16-kDa protein has been named bovine UCRP.

Evaluation of the uterine environment early in pregnancy establishment to characterise cows with a potentially superior ability to support conceptus survival

“…A gradation of IFNT was present with less in non-gravid horns of IR pregnancies with large conceptuses compared with gravid horns and less again in gravid horns of pregnancies with small conceptuses followed by very little in their non-gravid horns. This has several implications, as IFNT stimulates a plethora of pregnancy-related endometrial genes (see review, Spencer et al 2008) including ISG15 (Austin et al 1996), whose protein levels were greater in the gravid compared with non-gravid horns in the present study. Increased stimulation of the uterus would, in theory, provide a more favourable environment for the growth of the conceptus and, as a consequence, an increase in the numbers of binucleate cells available to secrete pregnancy-enhancing proteins such as CSH1 (Wooding 1992) and PAG9 (Green et al 2000).…”

Função do interferon-tau durante o reconhecimento materno da gestação em ruminantes

“…A ISG15 (gene estimulado por inteferon 15) é uma proteína que possui função semelhante a uma ubiquitina (AUSTIN et al, 1996) e é expressa no útero durante o início da gestação em resposta ao IFNT. Contudo, por meio de imunohistoquímica, sua presença foi também detectada em células luteais grandes do CL de ovelhas no dia 15 da gestação (OLIVEIRA et al, 2008).…”

“…Esses complexos se ligam a regiões definidas no DNA chamadas de elementos responsivos à estimulação por interferons (ISREs) que regulam a expressão de ISGs (HANSEN et al, 1999). Dentre os ISGs que aumentam sua expressão durante o início da gestação em resposta ao IFNT, estão o 2',5' oligoadenilato sintetase (OAS; MIRANDO et al, 1991;SCHMITT et al, 1993;JOHNSON et al, 2001), o gene de resistência ao myxovirus 1 (MX1; (OTT et al, 1998) e o gene estimulado pelo interferon 15 (ISG15; NAIVAR et al, 1995;AUSTIN et al, 1996;JOHNSON et al, 1999). Estudos recentes demonstraram a expressão de ISGs em células do sangue (YANKEY et al, 2001;HAN et al, 2006;GIFFORD et al, 2007) e CL (OLIVEIRA et al, 2008;BOTT et al, 2010) logo após a sinalização por IFNT no início da gestação em ruminantes.…”

“…A ISG15 recebeu inicialmente o nome de proteína com reação cruzada à ubiquitina por apresentar reação cruzada com o anticorpo contra ubiquitina (AUSTIN et al, 1996). Além disso, também foi demonstrado que ela está aumentada no endométrio de ruminantes (AUSTIN et al, 1996;HANSEN et al, 1997;PERRY et al, 1999;THATCHER et al, 2001), camundongos (AUSTIN et al, 2003) e primatas (BEBINGTON et al, 1999) em resposta à gestação.…”

“…Além disso, também foi demonstrado que ela está aumentada no endométrio de ruminantes (AUSTIN et al, 1996;HANSEN et al, 1997;PERRY et al, 1999;THATCHER et al, 2001), camundongos (AUSTIN et al, 2003) e primatas (BEBINGTON et al, 1999) em resposta à gestação. A ISG15 pode conjugar-se covalentemente a outras proteínas (LOEB & HAAS, 1992).…”