In this study there is a limitation in the

In this study, there is a limitation in the study of sex differences. Only female rats were used in our study. This is because the rats cannot urinate autonomously after SCI. Manual SEW 2871 emptying was needed until reflex bladder emptying was established (Lu et al., 2008, Ma et al., 2015). Because of the anatomical differences in the urinary system, female rats are more likely to perform artificial urination than males. Therefore, using female rats can increase the comfort of animals after surgery, reduce infection and mortality. At the same time, it also can reduce the influence of non-injury factors (such as infection and sex hormones) on the local microenvironment of spinal cord, and is beneficial to study the change of HK3 caused by the injury factors.
Conflict of interest statement
Author contributions
Acknowledgments This study was supported by grants from the National Natural Science Foundation of China (Nos. 81571194, 81271363) and Key Program of Anhui Province for Outstanding Talents in University (gxbjZD2016071).
Introduction Microsporidia are a large group of intracellular parasites related to fungi that infect a wide range of animals and some protozoan species (Vivier, 1975, Scheid, 2007). Widely distributed in insects, microsporidia are considered to be long-term regulators of insect populations and may suppress outbreaks of herbivore pests (Bjornson and Oi, 2014). Paranosema (Nosema, Antonospora) locustae, an orthopteran pathogen, is the only microsporidian species produced as commercial product for biological control (Henry, 1985). The chronic nature of microsporidian infections and their metabolic dependence on infected host cells suggest that these parasites should finely regulate host metabolic pathways to ensure a sufficient supply of nutrients for replication and sporogenesis (Williams et al., 2014). In addition, intracellular pathogens must resist immune responses of host cell. Molecular mechanisms of the effects on the host produced by microsporidian infection remain unidentified. Like intracellular apicomplexans (Gilbert et al., 2007, Schmuckli-Maurer et al., 2009) and kinetoplastids (Nandan and Reiner, 2005, Costa et al., 2016), microsporidia probably secrete a variety of proteins affecting expression of host genes or interacting with host cell signaling pathways. Hexokinase (Hxk) is considered to be one of the most interesting proteins secreted into infected cells by microsporidia as there is good reason to believe that it is involved in the regulation of transcriptional activity of genes in nuclei of infected host cells. Hxk2 is a bifunctional protein in the yeast Saccharomyces cerevisiae and in cancer Hela cells, demonstrating dual nucleocytoplasmic cellular localization (Neary and Pastorino, 2010). In yeast nuclei, Hxk2 has been implicated in processes of glucose repression and induction of several genes of carbohydrate metabolism (Petit et al., 2000, Moreno and Herrero, 2002). Like the yeast enzyme, microsporidian Hxk may control the expression of host carbohydrate metabolism genes in infected host cells. Unlike other glycolytic enzymes, Hxk of the microsporidianNematocida parisiiis highly expressed at early stages of parasite intracellular development in Caenorhabdus elegans (Cuomo et al., 2012). Additionally, Hxks signal peptides of six microsporidian species were shown to cause secretion of reporter enzyme in the S. cerevisiae secretion trap system (Cuomo et al., 2012). Previously, we demonstrated secretion of P. locustae Hxk into infected adipocytes of Locusta migratoria and accumulation in the host cell nuclei (Senderskiy et al., 2014). In this study, P. locustae Hxk without N-terminal 12 aa peptide (to prevent entry into the secretory pathway) was expressed in the yeastPichia pastoris and in lepidopteran (Spodoptera frugiperda) Sf9 cells. During the course of expression, heterologous protein accumulated in the nuclei of insect cells but not in yeast cell nuclei.