Evaluation of the α-casein (CSN1S1) locus as a potential target for a site-specific transgene integration.

Transgenic animals are an important tool in biotechnology, including the production of recombinant proteins in the milk. Traditionally, expression constructs are based on hybrid vectors bearing mammary gland specific regulatory elements from the α-casein (Csn1s1), ß-casein (Csn2), whey acidic protein (WAP), or ß-lactoglobulin (BLG) genes. Overexpression from the randomly integrated vectors typically provides high levels of expression, but has drawbacks due to unpredictable genome localization. CRISPR-Cas9 targeted transgene integration into the endogenous casein locus could alleviate the need for extensive animal screening to achieve high and reproducible expression levels. We decided to evaluate such a "precise" integration approach, placing the human granulocyte-macrophage colony-stimulating factor (hGMCSF) gene under control of the mouse endogenous alpha-S1-casein (Csn1s1) promoter. We designed two types of transgene integrations: a knock-in in the second exon of the Csn1s1 (INS-GM) and a full-size Csn1s1 replacement with hGMCSF (REP-GM) which was never tested before. The INS-GM approach demonstrated low transgene expression and milk protein levels (0.4% of Csn2 transcripts; 2-11 µg/ml hGMCSF). This was probably caused by the absence of the 3'-polyadenylation signal in the hGMCSF transgene. REP-GM animals displayed high transgene expression, reaching and slightly exceeding the level of the endogenous Csn1s1 (30-40% of Csn2 transcripts), but yielded less hGMCSF protein than expected (0.2-0.5 mg/ml vs 25 mg/ml of Csn1s1), indicating that translation of the protein is not optimal. Homozygous inserts leading to the Csn1s1 knock-out did not have any long standing effects on the animals' health. Thus, in our experimental design, site-specific transgene integration into the casein locus did not provide any significant advantage over the overexpression approach.

Pharmacological effects of fibroblast growth factor 21 are sex-specific in mice with the lethal yellow (Ay) mutation.

Hypothalamic melanocortin 4 receptors (MC4R) regulate energy balance. Mutations in the MC4R gene are the most common cause of monogenic obesity in humans. Fibroblast growth factor 21 (FGF21) is a promising antiobesity agent, but its effects on melanocortin obesity are unknown. Sex is an important biological variable that must be considered when conducting preclinical studies; however, in laboratory animal models, the pharmacological effects of FGF21 are well documented only for male mice. We aimed at investigating whether FGF21 affects metabolism in male and female mice with the lethal yellow (Ay) mutation, which results in MC4R blockage and obesity development. Obese C57Bl-Ay male and female mice were administered subcutaneously for 10 days with vehicle or FGF21 (1 mg per 1 kg). Food intake (FI), body weight (BW), blood parameters, and gene expression in the liver, muscles, brown adipose tissue, subcutaneous and visceral white adipose tissues, and hypothalamus were measured. FGF21 action strongly depended on the sex of the animals. In the males, FGF21 decreased BW and insulin blood levels without affecting FI. In the females, FGF21 increased FI and liver weight, but did not affect BW. In control Ay-mice, expression of genes involved in lipid and glucose metabolism (Ppargc1a, Cpt1, Pck1, G6p, Slc2a2) in the liver and genes involved in lipogenesis (Pparg, Lpl, Slc2a4) in visceral adipose tissue was higher in females than in males, and FGF21 administration inhibited the expression of these genes in females. FGF21 administration decreased hypothalamic POMC mRNA only in males. Thus, the pharmacological effect of FGF21 were significantly different in male and female Ay-mice; unlike males, females were resistant to catabolic effects of FGF21.

TNFα is responsible for the canonical offspring number-size trade-off.

There is a canonical life-history trade-off between quantity and quality of offspring, but molecular determinants for this are unknown. Here, we show that knockout of tumor necrosis factor (TNF-KO) in mice switched a relation between the number and size of developing embryos from expectedly negative to unexpectedly positive. Depletion of TNFα imbalanced humoral and trophic maintenance of embryo growth during gestation with respect to the litter size. The levels of embryotrophic GM-CSF cytokine and placental efficiency attained positive correlations with the number and size of embryos in TNF-KO females. Thus, TNFα oversees mother's resource allocations to balance embryo growth with the number of offspring. Consequently, this suggests an intricate link between the number-size trade-off and immunity given a pivotal role of TNFα in immune homeostasis.

Effects of cholesterol and nuclear hormone receptor agonists on the production of transforming growth factor-beta in macrophages.

We studied the effects of cholesterol, its oxidized derivatives mevalonate, and nuclear receptor agonists LXR, RXR, and FXR on the production of transforming growth factor-beta1 (TGF- beta1) by macrophages. After recruiting of macrophage monocytes into the focus of inflammation, the production of TGF-beta1 increased by 3.5 times in comparison with control macrophages. Cholesterol diet stimulated the production of TGF-beta1 by 2.5 times. Cholesterol directly stimulated macrophage production of TGF-beta1 in vitro, while addition of mevalonate to the incubation medium effectively reduced this induced production. Agonists of nuclear receptor sharply reduced the production of TGF-beta1 in recruited macrophages. Under conditions of inflammation, hypercholesterolemia can be a factor of fibrogenesis due to TGF-beta1 induction in macrophages, which depends on the products of mevalonate biochemical chain.

Peculiarities of bone marrow hemopoiesis in early aging OXYS rats.

Colony-forming activity of bone marrow cells in 3- and 12-month-old Wistar rats does not differ by the number of early and erythroid precursors and by the formation of granulocyte-macrophage colonies. In senescence-accelerated OXYS rats, the number of early and erythroid precursors significantly increases by the age of 12 months and surpasses the corresponding values in Wistar rats. The number of granulocyte-macrophage colonies in OXYS rats does not change with age, but the numbers of these colonies formed at the age of 3 and 12 months in these animals are higher than in Wistar rats. As a result, the total number of hemopoietic colonies in 12-month-old OXYS rats 2-fold surpassed that in 12-month-old Wistar rats. Activation of granulopoiesis and increased numbers of early and erythroid precursors indicate deep changes in the functional status of the hemopoietic stem cell in 1-year-old OXYS rats in the direction characteristic of aging animals.

Cell cycle of bone marrow CD34+ cells during autoimmune disease development in MRLMpJ/lpr mice.

The development of autoimmune disease in Fas-deficient MRLMpJ/lpr mice is associated with a relative decrease in the content of bone marrow CD34+ cells, which can attest to intensification of migration of early hemopoietic precursors from the bone marrow. The intensity of CD34+ apoptosis is high in young healthy MRLMpJ/lpr mice in comparison with the control, but decreases during the development of autoimmune disease. Proliferative activity of CD34+ cell population surpassed the control in all mouse groups, except AID2. The detected shifts in quantitative and qualitative parameters of CD34+ cells attest to an important role of stem hemopoietic precursors in the formation of autoimmune disease in MRLMpJ/lpr mice.