Genetic Inactivation of Trpml3 Does Not Lead to Hearing and Vestibular Impairment in Mice

TRPML3, a member of the transient receptor potential (TRP) family, is an inwardly rectifying, non-selective Ca2+-permeable cation channel that is regulated by extracytosolic Na+ and H+ and can be activated by a variety of small molecules. The severe auditory and vestibular phenotype of the TRPML3(A419P) varitint-waddler mutation made this protein particularly interesting for inner ear biology. To elucidate the physiological role of murine TRPML3, we conditionally inactivated Trpml3 in mice. Surprisingly, lack of functional TRPML3 did not lead to circling behavior, balance impairment or hearing loss

Harmonin-b, an actin-binding scaffold protein, is involved in the adaptation of mechanoelectrical transduction by sensory hair cells

We assessed the involvement of harmonin-b, a submembranous protein containing PDZ domains, in the mechanoelectrical transduction machinery of inner ear hair cells. Harmonin-b is located in the region of the upper insertion point of the tip link that joins adjacent stereocilia from different rows and that is believed to gate transducer channel(s) located in the region of the tip link's lower insertion point. In Ush1cdfcr-2J/dfcr-2J mutant mice defective for harmonin-b, step deflections of the hair bundle evoked transduction currents with altered speed and extent of adaptation. In utricular hair cells, hair bundle morphology and maximal transduction currents were similar to those observed in wild-type mice, but adaptation was faster and more complete. Cochlear outer hair cells displayed reduced maximal transduction currents, which may be the consequence of moderate structural anomalies of their hair bundles. Their adaptation was slower and displayed a variable extent. The latter was positively correlated with the magnitude of the maximal transduction current, but the cells that showed the largest currents could be either hyperadaptive or hypoadaptive. To interpret our observations, we used a theoretical description of mechanoelectrical transduction based on the gating spring theory and a motor model of adaptation. Simulations could account for the characteristics of transduction currents in wild-type and mutant hair cells, both vestibular and cochlear. They led us to conclude that harmonin-b operates as an intracellular link that limits adaptation and engages adaptation motors, a dual role consistent with the scaffolding property of the protein and its binding to both actin filaments and the tip link component cadherin-23

Externalizing behaviors in preadolescents: familial risk to externalizing behaviors and perceived parenting styles

The aim was to investigate the contribution of familial risk to externalizing behaviors (FR-EXT), perceived parenting styles, and their interactions to the prediction of externalizing behaviors in preadolescents. Participants were preadolescents aged 10–12 years who participated in TRAILS, a large prospective population-based cohort study in the Netherlands (N = 2,230). Regression analyses were used to determine the relative contribution of FR-EXT and perceived parenting styles to parent and teacher ratings of externalizing behaviors. FR-EXT was based on lifetime parental externalizing psychopathology and the different parenting styles (emotional warmth, rejection, and overprotection) were based on the child’s perspective. We also investigated whether different dimensions of perceived parenting styles had different effects on subdomains of externalizing behavior. We found main effects for FR-EXT (vs. no FR-EXT), emotional warmth, rejection, and overprotection that were fairly consistent across rater and outcome measures. More specific, emotional warmth was the most consistent predictor of all outcome measures, and rejection was a stronger predictor of aggression and delinquency than of inattention. Interaction effects were found for FR-EXT and perceived parental rejection and overprotection; other interactions between FR-EXT and parenting styles were not significant. Correlations between FR-EXT and perceived parenting styles were absent or very low and were without clinical significance. Predominantly main effects of FR-EXT and perceived parenting styles independently contribute to externalizing behaviors in preadolescents, suggesting FR-EXT and parenting styles to be two separate areas of causality. The relative lack of gene–environment interactions may be due to the epidemiological nature of the study, the preadolescent age of the subjects, the measurement level of parenting and the measurement level of FR-EXT, which might be a consequence of both genetic and environmental factors

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]