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BackgroundOligoteratoasthenozoospermia (OTA) combines deteriorated quantity, morphology and motility of the sperm, resulting in male factor infertility.MethodsWe used whole genome genotyping and exome sequencing to identify the mutation causing OTA in four men in a consanguineous Bedouin family. We expressed the normal and mutated proteins tagged with c-Myc at the carboxy termini by transfection with pCDNA3.1 plasmid constructs to evaluate the effects on protein stability in HEK293 cells and on the kinetics of actin repolymerisation in retinal pigment epithelium cells. Patients’ sperm samples were visualised by transmission electron microscopy to determine axoneme structures and were stained with fluorescent phalloidin to visualise the fibrillar (F)-actin.ResultsA homozygous missense mutation in Ciliogenesis Associated TTC17 Interacting Protein (CATIP): c. T103A, p. Phe35Ile, a gene encoding a protein important in actin organisation and ciliogenesis, was identified as the causative mutation with a LOD score of 3.25. The mutation reduces the protein stability compared with the normal protein. Furthermore, overexpression of the normal protein, but not the mutated protein, inhibits repolymerisation of actin after disruption with cytochalasin D. A high percentage of spermatozoa axonemes from patients have abnormalities, as well as disturbances in the distribution of F-actin.ConclusionThis is the first report of a recessive mutation in CATIP in humans. The identified mutation may contribute to asthenozoospermia by its involvement in actin polymerisation and on the actin cytoskeleton. A mouse knockout homozygote for CATIP was reported to demonstrate male infertility as the sole phenotype.

The present study investigated the association between oocyte zona pellucida shear modulus (ZPSM) and implantation rate (IR). Ninety-three oocytes collected from 38 in-vitro fertilization patients who underwent intracytoplasmic sperm injection were included in this case–control study. The ZP was modeled as an isotropic compressible hyperelastic material with parameter $$C_{10}$$ C 10 , which represents the ZPSM. Computational methodology was used to calculate the mechanical parameters that govern ZP deformation. Fifty-one developed embryos were transferred and divided into two groups—implanted and not implanted. Multivariate logistic regression analysis was performed to identify the association between ZPSM and IR while controlling for confounders. Maternal age and number of embryos per transfer were significantly associated with implantation. The IR of embryos characterized by $$C_{10}$$ C 10 values in the range of 0.20–0.40 kPa was 66.75%, while outside this range it was 6.70%. This range was significantly associated with implantation (p p = 0.001). The present study suggests that ZPSM may improve the classic embryo selection process with the aim of increasing IR.

Zinc in the pancreas is co-released with insulin from beta-cells reaching concentrations similar to those found in the vicinity of glutamatergic synapses. In the brain, the role of zinc in excitotoxic brain damage is well established. In contrast, its role in islet destruction during diabetes is poorly understood. We have studied the efficacy of zinc homeostatic proteins and an intracellular zinc chelator, clioquinol, in conferring resistance against zinc toxicity in pancreatic islets. We further assessed the ability of clioquinol to protect the islets in an experimental model of type I diabetes. Our results indicate that endogenous mechanisms for lowering [Zn]i are deficient in the insulinoma cell line, MIN6, and that permeation of Zn2+ triggered cell death. Application of the low affinity, intracellular zinc chelator, clioquinol, reduced Zn2+-induced cell death by 80%. In addition, chelation of zinc ions by clioquinol in vivo prevented onset of multiple low dose streptozotocin-induced diabetes, and reduced the insulitis and hyperglycemia associated with this model. Furthermore, the glucose tolerance test (GTT) score of multiple low dose streptozotocin (MLD-STZ) mice pretreated with clioquinol was, statistically indistinguishable from that of untreated, control mice. Taken together, our results point to the potential utility of in vivo zinc chelation as a therapeutic strategy for treatment of idiopathic type I diabetes.

In the mammalian pancreas, high concentrations of Zn(2+) are co-secreted with insulin, which may then permeate via abundant L-type Ca(2+) channels (LTCC) present on the beta-cells. Neither the mechanisms utilized by these cells to lower cytosolic Zn(2+) nor the implications of increased intracellular Zn(2+) on beta-cell survival are well understood. To address this, we employed cell imaging of Zn(2+) and Ca(2+) in the beta-insulinoma cell line, Min6. Depolarization induced an intense zinc influx that was blocked by nifedipine and verapamil, indicating that Zn(2+) permeates via the LTCC. Both Ca(2+) and Zn(2+) permeated concomitantly, yet while Ca(2+) was subsequently removed from the cytosol, Zn(2+) was retained in the cells. Fluorescent staining of vesicular Zn(2+) using ZP1 demonstrated that Zn(2+) could be slowly sequestered following a brief exposure to low concentration of Zn(2+). In contrast, cells were unable to sequester Zn(2+) following application of high concentrations, which was followed by massive cell death. Our results demonstrate homeostatic crosstalk between the plasma membrane and intracellular zinc transporters and suggest that attenuating zinc influx may enhance beta-cell survival.