Generation of WNK1 knockout cell lines by CRISPR/Cas-mediated genome editing

Sodium-coupled SLC12 cation chloride cotransporters play important roles in cell volume and chloride homeostasis, epithelial fluid secretion, and renal tubular salt reabsorption. These cotransporters are phosphorylated and activated indirectly by With-No-Lysine (WNK) kinases through their downstream effector kinases, Ste20- and SPS1-related proline alanine-rich kinase (SPAK) and oxidative stress-responsive kinase 1 (OSR1). Multiple WNK kinases can coexist within a single cell type, although their relative contributions to SPAK/OSR1 activation and salt transport remain incompletely understood. Deletion of specific WNKs from cells that natively express a functional WNK-SPAK/OSR1 network will help resolve these knowledge gaps. Here, we outline a simple method to selectively knock out full-length WNK1 expression from mammalian cells using RNA-guided clustered regularly interspaced short palindromic repeats/Cas9 endonucleases. Two clonal cell lines were generated by using a single-guide RNA (sgRNA) targeting exon 1 of the WNK1 gene, which produced indels that abolished WNK1 protein expression. Both cell lines exhibited reduced endogenous WNK4 protein abundance, indicating that WNK1 is required for WNK4 stability. Consistent with an on-target effect, the reduced WNK4 abundance was associated with increased expression of the KLHL3/cullin-3 E3 ubiquitin ligase complex and was rescued by exogenous WNK1 overexpression. Although the morphology of the knockout cells was indistinguishable from control, they exhibited low baseline SPAK/OSR1 activity and failed to trigger regulatory volume increase after hypertonic stress, confirming an essential role for WNK1 in cell volume regulation. Collectively, our data show how this new, powerful, and accessible gene-editing technology can be used to dissect and analyze WNK signaling networks.

Glutathione S-transferases M1, T1, and P1 and breast cancer

We examined associations for glutathione S-transferases M1 (GSTM1), T1 (GSTT1), and P1 (GSTP1) genotypes and breast cancer in the Carolina Breast Cancer Study, a population-based, case-control study in North Carolina. Odds ratios were close to the null value for each GST locus among African-American women (278 cases and 271 controls) and white women (410 cases and 392 controls), as well as pre- and postmenopausal women. For women with a history of breast cancer in one or more first-degree relatives, odds ratios were 2.1 (95% confidence interval, 1.0-4.2) for GSTM1 null and 1.9 (0.8-4.6) for GSTT1 null genotypes. Among women with a family history, age at diagnosis was significantly earlier for those with the GSTM1 null genotype. We did not observe strong evidence for modification of odds ratios for smoking according to GST genotypes. There was no evidence for combined effects of GSTM1, GSTT1, and GSTP1 genotypes, and there were no combined effects for GST genotypes and the catechol O-methyltransferase genotype. We conclude that GSTM1, GSTT1, and GSTP1 genotypes do not play a strong role in susceptibility to breast cancer. However, the role of GST genotypes in age at onset and risk of breast cancer among women with a family history merits further investigation.

Association of prostate cancer with vitamin D receptor gene polymorphism

The incidence of prostate cancer in the United States is second only to skin cancers, and the disease kills almost the same number of men as breast cancer does women. Relatively few risk factors are known for prostate cancer, although several lines of evidence suggest that vitamin D may be an important determinant of prostate cancer risk. A series of common polymorphisms in the vitamin D receptor gene were recently reported to be associated with bone density and risk of osteoporosis (Morrison et al., Nature (Lond.), 367: 284-287, 1994). These genetic variants have been correlated with both circulating levels of active vitamin D hormone and in vitro measures of gene expression (Morrison et al., Nature (Lond.), 367: 284-287, 1994). We tested the hypothesis that vitamin D receptor gene polymorphisms are associated with prostate cancer risk using a case-control study of 108 men undergoing radical prostatectomy and 170 male urology clinic controls with no history of cancer. Among the white control group, 22% were homozygous for the presence of a TaqI RFLP at codon 352 (genotype tt), but only 8% of cases had this genotype (P < 0.01). A similar trend was seen among the small number of blacks in this study (13% for controls, 8% for cases), although the difference was not statistically significant. Race-adjusted combined analysis suggests that men who are homozygous for the t allele (shown to correlate with higher serum levels of the active form of vitamin D) have one-third the risk of developing prostate cancer requiring prostatectomy compared to men who are heterozygotes or homozygous for the T allele (odds ratioMH = 0.34; 95% confidence interval, 0.16-0.76; P < 0.01). These results support recent ecological, population, and in vitro studies suggesting that vitamin D is an important determinant of prostate cancer risk and, if confirmed, suggest strategies for chemoprevention of this common cancer.

Chronic psychiatric patients in the community

A feasibility study is presented which describes a cohort of 102 chronic psychiatric patients. The cases were selected on the criterion of four or more new admissions to psychiatric services in the Hamilton-Wentworth region during the year 1977. The group was predominately in the age 20-39 year range and both sexes were represented about equally. The diagnostic labels were personality disorder, schizophrenia, depression and alcoholism in descending order of frequency. The large majority were socially isolated and had contact with social agencies and the police. Seven deaths occurred in the cohort during the year of study.

Effect of Eimeria species on the appearance of radioactivity in the blood of chicks fed radio-labeled glucose or 3-0-methyl-D-glucose

Results of five trials with four species of coccidia (Eimeria acervulina, E. necatrix, E. tenella, and E. brunetti) failed to demonstrate any interference with glucose absorption in the parasitized intestines of intact chick hosts. In addition, circulating blood radioactivity in severely parasitized chicks, as evidenced by weight gain data and intestinal lesion scores, was significantly higher than that in control chicks following oral administration of 14C-glucose or 3-0-methyl-D-14C-glucose at 6 days postinfection. During the recovery phase of the infection (14 to 21 days postinfection), severely infected chicks rapidly gained weight and the blood radioactivity of parasitized chicks was consistently higher than that of uninfected control chicks. No significant differences in weight or blood radioactivity were observed during the post-recovery period (28 to 35 days postinfection).