MKRN3 inhibits puberty onset via interaction with IGF2BP1 and regulation of hypothalamic plasticity.

Makorin ring finger protein 3 (MKRN3) was identified as an inhibitor of puberty initiation with the report of loss-of-function mutations in association with central precocious puberty. Consistent with this inhibitory role, a prepubertal decrease in Mkrn3 expression was observed in the mouse hypothalamus. Here, we investigated the mechanisms of action of MKRN3 in the central regulation of puberty onset. We showed that MKRN3 deletion in hypothalamic neurons derived from human induced pluripotent stem cells was associated with significant changes in expression of genes controlling hypothalamic development and plasticity. Mkrn3 deletion in a mouse model led to early puberty onset in female mice. We found that Mkrn3 deletion increased the number of dendritic spines in the arcuate nucleus but did not alter the morphology of GnRH neurons during postnatal development. In addition, we identified neurokinin B (NKB) as an Mkrn3 target. Using proteomics, we identified insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) as another target of MKRN3. Interactome analysis revealed that IGF2BP1 interacted with MKRN3, along with several members of the polyadenylate-binding protein family. Our data show that one of the mechanisms by which MKRN3 inhibits pubertal initiation is through regulation of prepubertal hypothalamic development and plasticity, as well as through effects on NKB and IGF2BP1.

Challenges in harmonizing integrated healthcare network laboratories: Multi-center evaluation of the AccuTnI+3 troponin assay.

BACKGROUND: Beckman Coulter has recently introduced a new troponin assay manufactured for the Access2 and DxI platforms, releasing it under the name AccuTnI+3. Clinical laboratories are required to validate method performance before testing and reporting patient results. METHODS: Beckman Coulter Access 2 instruments (n=42) across Kaiser Permanente Northern California were evaluated for their performance characteristics using the AccuTnI+3 reagent. Precision, linearity, and patient sample comparisons were performed on each instrument. Limit of the blank (LOB), limit of detection (LOD), limit of quantitation (LOQ), serum plasma comparisons, and specimen stability were evaluated using a single instrument. RESULTS: The assay was linear from 0-100,000ng/L. The LOB, LOD and LOQ were determined to be 5, 8 and 20ng/L, respectively. Interday precision on the low QC (mean concentration 41ng/L) ranged from 3.0% to 14.2%. The bias observed between the former assay (AccuTnI) and the AccuTnI+3 was comparable to the inter-instrument bias for either assay. Non-uniform distribution was observed in the precision and inter-instrument/inter-assay comparisons among the instruments evaluated. CONCLUSIONS: The AccuTnI and AccuTnI+3 troponin assays are equivalent across the analytical measuring range. There was no significant difference at the medical decision point. No changes in patient results are anticipated. However, the assay-independent inter-instrument bias observed is an important consideration for harmonization efforts.