Decreased cognitive function of ALG13KO female mice may be related to the decreased plasticity of hippocampal neurons.

Asparagine-linked glycosylation 13 (ALG13) is an X-linked gene that encodes a protein involved in the glycosylation of the N-terminus. ALG13 deficiency leads to ALG13-congenital disorders of glycosylation (ALG13-CDG), usually in females presenting with mental retardation and epilepsy. Cognitive function is an important function of the hippocampus, and forms the basis for learning, memory and social abilities. However, researchers have not yet investigated the effect of ALG13 on hippocampal cognitive function. In this study, the exploration, learning, memory and social abilities of ALG13 knockout (KO) female mice were decreased in behavioral experiments. Golgi staining demonstrated a decrease in the complexity of hippocampal neurons. Western blot and immunofluorescence staining of the synaptic plasticity factors postsynaptic density protein 95 (PSD95) and synaptophysin (SYP) displayed varying degrees of decline. In other words, the KO of ALG13 may have reduced the expression of PSD95 and SYP in the hippocampus of female mice. Moreover, it may have lowered the synaptic plasticity in various areas of the hippocampus, thus resulting in decreased dendrite length, complexity, and dendrite spine density, which affected the hippocampal function and reduced the cognitive function in female mice.

MSTN modification in goat mediated by TALENs and performance analysis.

Myostatin (MSTN) is a negative regulator of skeletal muscle growth and development. It can inhibit the proliferation of myoblasts and serve as an important candidate gene for animal breed improvement. Mutations of the MSTN gene can cause extensive skeletal muscle hyperplasia and hypertrophy, resulting in "double muscle" symptoms. This leads to reduction of animal fat differentiation and increase of muscle content, thereby meeting the demand for quality consumption of animal meat in the market. In order to obtain a double-muscle phenotype using mutant MSTN gene in cloned goat, the goat MSTN gene was target-modified by TALENs. In this study, the TALENs expression vector was designed and constructed in the first exon sequence of the goat MSTN gene, which was then transfected into the goat fetal fibroblasts. The resistant cell lines were obtained by puromycin selection, and the cell lines with the MSTN gene mutations were analyzed by PCR and gene sequencing, thereby identifying the mutation type(s). The MSTN gene mutant cell lines were used as the nuclear donor cells in somatic cell nuclear transfer procedures in goats, and The morphological structure of the muscle tissue of the goats with MSTN gene mutations was analyzed by tissue section. The body weight of the cloned goats were monitored at different months of age, which provided the growth trend of their weight at different developmental stages. The results show that a total of 109 MSTN gene mutant cell lines were obtained. The mutation efficiency was 79.0% (109/138), of which 46 were biallelic mutations, accounting for 33.3% (46/138) of the total cell lines. Four MSTN gene mutant cell lines (1 biallelic homozygous mutation, 3 non-homozygous mutations) with good growth status were selected for somatic cell nuclear transfer in 12 recipients, of which 4 were pregnant by B-ultrasound at 30 days, indicating the a 33.3% (4/12) pregnancy rate. Two cloned goats were born at the end of the pregnancy. Sequencing analysis showed that there was no mutation in one allele of the M-1 cloned lamb, and the other allele harbored a 3 bp-deletion. The M-2 cloned lamb harbored a 1 bp base insertion in one allele of the MSTN gene, and a deletion of 13 bp in the other allele, resulting in mutations in both alleles and the loss of the protein-coding sequence of MSTN after the mutation site. In addition, the muscle fibers of cloned M-1 goats are tightly arranged and thick, and their monthly body weight is higher than that of normal wild-type goats. However, it is still consistent with the growth trend of normal wild-type goats and the M-1 goats can develop into healthy adults. In summary, this study showed that goat fetal fibroblasts with the multiple MSTN gene mutations were successfully obtained by TALENs technology, and cloned goats with mutant MSTN genes could be generated by somatic cell nuclear transfer method, thereby providing a technical foundation for the cultivation of the "double muscle" phenotype goats, and serving as a reference method for the preparation of other transgenic animals in the future.

ALG13 participates in epileptogenesis via regulation of GABAA receptors in mouse models.

ALG13 (asparagine-linked glycosylation 13) plays crucial roles in the process of N-linked glycosylation. Mutations of the ALG13 gene underlie congenital disorders of glycosylation type I (CDG-I), a rare human genetic disorder with defective glycosylation. Epilepsy is commonly observed in congenital disorders of glycosylation type I (CDG-I). In our study, we found that about 20% of adult ALG13KO knockout mice display spontaneous seizures, which were identified in a simultaneous video and intracranial EEG recording. However, the mechanisms of ALG13 by which deficiency leads to epilepsy are unknown. Whole-cell patch-clamp recordings demonstrated that ALG13KO mice show a marked decrease in gamma-aminobutyric acid A receptor (GABAAR)-mediated inhibitory synaptic transmission. Furthermore, treatment with low-dose diazepam (a positive allosteric modulator of GABAA receptors), which enhances GABAAR function, also markedly ameliorates severity of epileptic seizures in ALG13KO mice. Moreover, ALG13 may influenced the expression of GABAARα2 membrane and total protein by changing transcription level of GABAARα2. Furthermore, protein interactions between ALG13 and GABAARα2 were observed in the cortex of wild-type mice. Overall, these results reveal that ALG13 may be involved in the occurrence of epilepsy through the regulation of GABAAR function, and may provide new insight into epilepsy prevention and treatment.

ALG13 Deficiency Associated with Increased Seizure Susceptibility and Severity.

ALG13 (asparagine-linked glycosylation 13 homolog) encodes a crucial protein involved in the process of N-linked glycosylation, and abnormal N-linked glycosylation is considered an important risk factor that leads to neurological deficits and disorders. However, the causal relationship between ALG13 and epilepsy remains unknown. This study applied a kainic acid (KA)-induced epileptic mouse model to determine whether ALG13 deficiency resulted in increased susceptibility to and severity of epileptic seizures. This report found that the expression of ALG13 in the central nervous system (CNS) had histologically and cellular specificity, mainly in the neurons in the cortex and hippocampus, epilepsy commonly occurs. In addition, KA-induced seizures significantly affected the expression levels of ALG13 mRNA and protein in the forebrain of wild-type (WT) mice. KA-induced epileptic progressions were dramatically increased in Alg13 knockout (KO) mice, including prolonged electrographic seizures, strikingly increased mortality rates, and the severity of responses to epileptic seizures. Furthermore, KA-induced epilepsy-related pathological changes of the brain were predominantly exacerbated in Alg13 KO mice. This study also preliminarily explored the possible mechanisms of ALG13-involved epilepsy by showing hyperactive mTOR signaling pathways in the cortex and hippocampus of Alg13 KO mice. To the best of our knowledge, this report is the first evidence of the association between ALG13 and epilepsy in experimental animals.

Oocyte-G1 promotes male germ cell apoptosis through activation of Caspase-3.

Apoptosis plays a vital role in the developmental process of the mammalian reproduction system, such as during folliculogenesis or spermatogenesis. Kinesin superfamily (Kif) proteins are responsible for intercellular transportation, and their malfunction can induce cell apoptosis. Oocyte-G1 is a new Kif member. Our previous study suggested that abnormal expression of Oocyte-G1 induced abnormal development of ovarian follicle and testes, but the underlying mechanism was not fully discovered. Therefore, in this study, the cellular role and mechanism of Oocyte-G1 were investigated. Transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL) result showed that overexpression of Oocyte-G1 increased apoptosis in cultured cells. Oocyte-G1 transgenic mice also showed an increased apoptotic rate in male germ cells compared with controls. Immunoprecipitation and co-localization experiments revealed an interaction between Oocyte-G1 and Caspase-3. Expression levels of Caspase-3 were upregulated in cells overexpressing Oocyte-G1 and downregulated in Oocyte-G1 knockdown cells. These results suggest that Oocyte-G1 may promote male germ cell apoptosis through activating Caspase-3.

Effects of bisphenol A on ovarian follicular development and female germline stem cells.

Bisphenol A (BPA), one of the most frequently detected emerging pollutants in the environment, has been implicated in adverse effects in male and female reproduction at extremely low concentrations. This study aimed to investigate the effects and potential mechanism of BPA on mouse ovarian follicular development and female germline stem cells (FGSCs). Female CD-1 adult mice were administered gradient concentrations of BPA (12.5, 25, and 50 mg/kg/day) by intraperitoneal injection. We found that the number of atretic ovarian follicles was significantly increased at high BPA concentrations. Additionally, the numbers of primordial follicles, primary follicles, and corpus luteum (CL) were significantly reduced at high BPA concentrations. Interestingly, the number of FGSCs was remarkably reduced in BPA-treated ovaries. Furthermore, the increased apoptotic rate of FGSCs in vitro was triggered by BPA accompanied by increased BPA concentrations. To investigate the mechanism of BPA in ovarian follicular development, 193 differentially expressed proteins were identified in BPA-treated ovaries by the isobaric tags for relative and absolute quantification-coupled 2D liquid chromatography-mass spectrometry technique. A total of 106 proteins were downregulated and 85 proteins were upregulated. Among these proteins, the apoptosis-related protein SAFB-like transcriptional modulator (SLTM) was remarkably upregulated, and this result was consistent with western blotting. Taken together, our results suggest that an ovarian follicular development, especially, the development of primordial follicles, primary follicles, and the CL, is inhibited by high BPA concentrations, and the ovarian follicle atresia is initiated by BPA through upregulated expression of SLTM. Furthermore, BPA induces apoptosis of cultured FGSCs. The effect of BPA on ovarian follicular development and FGSCs, especially the effect on FGSCs, suggests a novel mechanism of how BPA causes female infertility.

Efficient TALEN-mediated myostatin gene editing in goats.

BACKGROUND: Myostatin (MSTN) encodes a negative regulator of skeletal muscle mass that might have applications for promoting muscle growth in livestock. In this study, we aimed to test whether targeted MSTN editing, mediated by transcription activator-like effector nucleases (TALENs), is a viable approach to create myostatin-modified goats (Capra hircus). RESULTS: We obtained a pair of TALENs (MTAL-2) that could recognize and cut the targeted MSTN site in the goat genome. Fibroblasts from pedigreed goats were co-transfected with MTAL-2, and 272 monoclonal cell strains were confirmed to have mono- or bi-allelic mutations in MSTN. Ten cell strains with different genotypes were used as donor cells for somatic cell nuclear transfer, which produced three cloned kids (K179/MSTN(-/-), K52-2/MSTN (+/-), and K52-1/MSTN (+/+)). CONCLUSIONS: The results suggested that the MTAL-2 could disrupt MSTN efficiently in the goat genome. The mutated somatic cells could be used to produce MSTN-site mutated goats without developmental disruption. Thus, TALENs is an effective method for accurate genome editing to produce site-modified goats.

High-level expression of a novel recombinant human plasminogen activator (rhPA) in the milk of transgenic rabbits and its thrombolytic bioactivity in vitro.

The human tissue-type plasminogen activator (tPA) is a key kinase of fibrinolysis that plays an important role in dissolving fibrin clots to promote thrombolysis. The recombinant human plasminogen activator (rhPA) has more thrombolytic advantages than the wild type tPA. To increase the half-life and thrombolytic activity of tPA, a mutant containing only the essential K2 fibrin-binding and P activating plasminogen domains of the wild type tPA was cloned. This fragment was then inserted into goat ß-casein regulatory sequences. Then, a mammary gland-specific expression vector, PCL25/rhPA, was constructed, and the transgenic rabbits were generated. In this study, 18 live transgenic founders (12♀, 6♂) were generated using pronuclear microinjection. Six transgenic rabbits were obtained, and the expression levels of rhPA in the milk had a range of 15.2-630 µg/ml. A fibrin agarose plate assay of rhPA showed that it had strong thrombolytic bioactivity in vitro, and the highest specific activity was >360 (360 times more than that of alteplase). The results indicated that the rhPA containing only the K2 and P domains is efficiently expressed with higher thrombolytic bioactivity in the milk of transgenic rabbits. Our study also demonstrated a new method for the large-scale production of clinically relevant recombinant pharmaceutical proteins in the mammary glands of transgenic rabbits.

Expression of recombinant human alpha-lactalbumin in the milk of transgenic goats using a hybrid pomoter/enhancer.

To improve nutrient content of goat milk, we describe the construction of a vector (pBLAC) containing a hybrid goat ß -lactoglobulin (BLG) promoter/cytomegalovirus (CMV) enhancer. We also describe the generation of transgenic goats expressing rhLA by somatic cell nuclear transfer (SCNT). Of 334 one-cell stage embryos derived from three transgenic cell lines and 99 embryos derived from non-transgenic (NT) cells surgically transferred to the oviducts of 37 recipients, two recipients delivered two kids (2%) from the non-transfected line and five recipients delivered six kids (1.8%) from transgenic cell lines, three of which died within 2 days. Compared to the NT donor cells, transfection of donor cells does not negatively affect the development of nuclear transfer embryos into viable transgenic offspring. However, the clone efficiency in cell line number 1 was lower than that in numbers 2 and 3, and in the NT lines (0.9% versus 1.9% 2.4% and 2%; P < 0.05). Two transgenic cloned goats expressed rhLA in the milk at 0.1-0.9 mg/mL. The mammary gland-specific expression vector pBLAC with hybrid BLG/CMV can drive the hLA gene to express in vitro and in vivo. These data establish the basis for use of a hybrid promoter/enhancer strategy to produce rhLA transgenic goats.

[Targeted exogenous EGFP gene editing in caprine fetus fibroblasts by zinc-finger nucleases].

Gene knockout by ZFNs (zinc-finger nucleases) is efficient and specific, and successfully applied in more than 10 organisms. Currently, it is unclear whether this technology can be used for knocking-out enhanced green fluorescent protein (EGFP) gene in transgenic goats. Here we constructed and used ZFN-coding plasmids to produce genetic knockouts in the cells of cloned fetus produced from donor cells by microinjection of EGFP gene. Following introduced plasmids into caprine primary cultured fetus fibroblasts by electroporation, targeting of a transgene resulted in sequence mutation. Using the flow cytometric analysis, we confirmed the disappearance of EGFP expression in treated cells. Sequence from PCR products corresponding to targeted site showed that insertion of a G into the exon of EGFP resulted in frame shift mutation. These results suggest that ZFN-mediated gene targeting can apply to caprine fetus fibroblasts, which may open a unique avenue toward the creation of gene knockout goats combining with somatic cell nuclear transfer.

Generation of human lactoferrin transgenic cloned goats using donor cells with dual markers and a modified selection procedure.

The objective was to use dual markers to accurately select genetically modified donor cells and ensure that the resulting somatic cell nuclear transfer kids born were transgenic. Fetal fibroblast cells were transfected with dual marking gene vector (pCNLF-ng) that contained the red-shifted variant of the jellyfish green fluorescent protein (LGFP) and neomycin resistance (Neo) markers. Cell clones that were G418-resistant and polymerase chain reaction-positive were subcultured for several passages; individual cells of the clones were examined with fluorescence microscopy to confirm transgenic integration. Clones in which every cell had bright green fluorescence were used as donor cells for nuclear transfer. In total, 86.7% (26/30) cell clones were confirmed to have transgenic integration of the markers by polymerase chain reaction, 76.7% (23/30) exhibited fluorescence, but only 40% (12/30) of these fluorescent cell clones had fluorescence in all cell populations. Moreover, through several cell passages, only 20% (6/30) of the cell clones exhibited stable LGFP expression. Seven transgenic cloned offspring were produced from these cells by nuclear transfer. Overall, the reconstructed embryo fusion rate was 76.6%, pregnancy rates at 35 and 60 days were 39.1% and 21.7%, respectively, and the offspring birth rate was 1.4%. There were no significant differences between nuclear transfer with dual versus a single (Neo) marker (overall, 73.8% embryo fusion rate, 53.8% and 26.9% pregnancy rates, and 1.9% birth rate with five offspring). In conclusion, the use of LGFP/Neo dual markers and an optimized selection procedure reliably screened genetically modified donor cells, excluded pseudotransgenic cells, and led to production of human lactoferrin transgenic goats. Furthermore, the LGFP/Neo markers had no adverse effects on the efficiency of somatic cell nuclear transfer.

Hybrid expression cassettes consisting of a milk protein promoter and a cytomegalovirus enhancer significantly increase mammary-specific expression of human lactoferrin in transgenic mice.

It is very important to develop an effective, specific, and robust expression cassette that ensures a high level of expression in the mammary glands. In this study, we designed and constructed a series of mammary gland-specific vectors containing a complex hybrid promoter/enhancer by utilizing promoter sequences from milk proteins (i.e., goat ß-casein, bovine αs1-casein, or goat ß-lactoglobulin) and cytomegalovirus enhancer sequences; vectors containing a single milk protein promoter served as controls. Chicken ß-globin insulator sequences were also included in some of these vectors. The expression of constructs was analyzed through the generation of transgenic mice. Enzyme-linked immunosorbent assay (ELISA) analysis revealed that the hybrid promoter/enhancer could drive the expression of recombinant human lactoferrin (rhLF) cDNA at high levels (1.17-8.10 mg/ml) in the milk of transgenic mice, whereas control promoters achieved a very low rhLF expression (7-40 ng/ml). Moreover, the expression of rhLF was not detected in the serum or saliva of any transgenic animal. This result shows that all constructs, driven by the hybrid promoter/enhancer, had high mammary gland-specific expression pattern. Together, our results suggest that the use of a hybrid promoter/enhancer is a valuable alternative approach for increasing mammary-specific expression of recombinant hLF in a transgenic mouse model.

[Cloning goat producing human lactoferrin with genetically modified donor cells selected by single or dual markers].

We compared the efficiency of cloning goat using human lactoferrin (hLF) with genetically modified donor cells marked by single (Neo(r)) or double (Neo(r)/GFP) markers. Single marker expression vector (pBLC14) or dual markers expression vector (pAPLM) was delivered to goat fetal fibroblasts (GFF), and then the transgenic GFF was used as donor cells to produce transgenic goats. Respectively, 58.8% (20/34) and 86.7% (26/30) resistant cell lines confirmed the transgenic integration by PCR. Moreover, pAPLM cells lines were subcultured with several passages, only 20% (6/30) cell lines was observed fluorescence from each cell during the cell passage. Somatic cell nuclear transfer using the donor cells harbouring pBLC14 or pAPLM construct, resulting in a total of 806 reconstructed embryos, a pregnancy rate at 35 d (53.8%, 39.1%) and 60 d (26.9%, 21.7%), and an offspring birth rate (1.9%, 1.4%) with 5 and 7 newborn cloned goats, respectively. Transgene was confirmed by PCR and southern-blot in all cloned offspring. There were no significant differences at the reconstructed embryo fusion rates, pregnancy rates and the birth rate (P > 0.05) between single and double markers groups. The Neo(r)/GFP double markers could improve the reliability for accurately and efficiently selecting the genetically modified donor cells. No adverse effect was observed on the efficiency of transgenic goat production by SCNT using somatic cells transfected with double (Neo(r)/GFP) markers vector.