The preparation of a viable suspension of epithelial cells from the rumen mucosa of cattle

Establishment of a bovine rumen epithelial cell line

Rumen epithelium plays an essential role in absorption, transport, and metabolism of short-chain fatty acids, the main products of rumen fermentation, and in preventing microbes and other potentially harmful rumen contents from entering the systemic circulation. The objective of this study was to generate an immortal rumen epithelial cell line that can be used as a convenient model of rumen epithelial cells in vitro. We isolated primary rumen epithelial cells from a steer through trypsin digestion and transduced them with lentiviruses expressing the Simian Virus (SV) 40 T antigen. We cloned the transduced cells by limiting dilution. Western blotting analysis confirmed the expression of the SV40 T antigen in two single-cell clones. Cells from one clone, named bovine rumen epithelial clone 1 (BREC1), displayed a flat and squamous morphology in culture. RNA sequencing revealed that BREC1 cells expressed many markers of epithelial cells, including keratins, the epidermal growth factor receptor, and the short-chain fatty acid transporters monocarboxylic acid transporter (MCT) 1 (MCT-1) and MCT-4. RNA sequencing revealed that BREC1 cells expressed key enzymes such as 3-hydroxymethyl-3-methylglutaryl-CoA lyase and 3-hydroxy-3-methylglutaryl-CoA synthase 1 involved in ketogenesis, a unique function of rumen epithelial cells. RNA sequencing also revealed the expression of genes encoding tight junctions, desmosomes, anchoring junctions, and polarized plasma membranes, structures typical of epithelial cells, in BREC1 cells. Cell proliferation assays indicated that BREC1 cells were similar to primary rumen epithelial cells in response to insulin-like growth factor 1, insulin, and butyrate. In conclusion, BREC1 is not only a convenient but an appropriate model for studying the factors and mechanisms that control proliferation, apoptosis, differentiation, nutrient transport, metabolism, and barrier function in rumen epithelium.

Isolation of Highly Viable Thymic Epithelial Cells for Use in In Vitro and In Vivo Experiments

Thymic epithelial cells (TECs) play multiple essential roles in T-cell development and the establishment of immune tolerance, but their isolation can be challenging, and their low viability upon isolation complicates downstream experiments. A method that allows TECs to be isolated easily and to survive afterward will be useful for elucidating key questions in TEC biology. Here, we demonstrate a simple method to isolate highly viable TECs. Primary TECs isolated using papain together with collagenase IV and DNase I survive and proliferate in vitro. Moreover, these primary TECs functionally engraft after intrathymic transplantation into recipient mice. Thus, the methods described herein will be useful for elucidating the roles of TECs and TEC subsets in T-cell development and immune tolerance.

The pathway of ketogenesis in rumen epithelium of the sheep

A method for the fractionation of sheep rumen epithelium with limited mitochondrial breakage is described. The distributions of the enzymes of the 3-hydroxy-3-methylglutaryl-CoA pathway of ketogenesis indicate that this process is exclusively mitochondrial. Enzyme activities are sufficient to account for the ketogenic rates found in vivo. The failure of (-)-hydroxycitrate to block ketogenic flux supports this view. 3-Hydroxybutyrate dehydrogenase activity is largely associated with particulate material in the mitochondrial fraction. ATP citrate lyase activity was found, with appreciable acetoacetyl-CoA thiolase and 3-hydroxy-3-methylglutaryl-CoA synthase in the cytoplasmic fraction.