Assessment of Zinc-alfa2 Glycoprotein (ZAG) and Lipase Maturation Factor 1 (LMF1) concentration in children with chronic kidney disease

ZAG (zinc-α2-glycoprotein) - adipokine, may participate in the mechanism of malnutrition in chronic kidney disease (CKD) as cachexia factor. The transmembrane protein of the endoplasmic reticulum - lipase maturation factor 1 (LMF1) is necessary for the secretion and enzymatic activity of lipases and lowering triglycerides level. The aim of the study was to evaluate these markers - ZAG and LMF1, their potential importance in CKD in children. The study included 59 children and adolescents aged 10.7±5.0 years with CKD. Compared with healthy children, serum and urine ZAG levels were higher in children with CKD. A similar relationship was obtained in the comparison of girls and boys between the above groups. We showed a reduced serum and urine concentration of LMF1 in children with CKD. Additionally, ZAG and LMF1 levels in children below 10 years of age and above 10 were no different. There was also no correlation between these markers and serum creatinine (except negative correlation of urinary ZAG), albumin, cholesterol, triglycerides. LMF1 concentration correlated positively with vitamin D level in dialyzed patients. To conclude, elevated serum ZAG levels in children with CKD document that selective kidney damage results in the rise of ZAG concentration, however the specific role of this marker in malnutrition was not documented. Reduced serum LMF1 concentration in children with CKD, did not correlate with standard parameters used to assess lipid metabolism and severity of CKD. The usefulness of LMF1 as the marker of the lipid metabolism disturbances in children with CKD was not proven.

Sperm cryopreservation impacts the early development of equine embryos by downregulating specific transcription factors

Equine embryos were obtained by insemination with either fresh or frozen-thawed spermatozoa at 8, 10 and 12 h post spontaneous ovulation, maintaining the pairs mare-stallion for the type of semen used. Next generation sequencing (NGS) was performed in all embryos and bioinformatic and enrichment analysis performed on the 21,058 identified transcripts. A total of 165 transcripts were downregulated in embryos obtained with cryopreserved spermatozoa respect embryos resulting from an insemination with fresh spermatozoa (p=0.021, q=0.1). The enrichment analysis using human orthologs using g:profiler on the downregulated transcripts marked an enrichment in transcription factors (TFs) in mRNAs downregulated in embryos obtained after insemination with cryopreserved spermatozoa. The 12 mRNAs (discriminant variables) most significantly downregulated in these embryos included among others, the chromatin-remodeling ATPase INO80, Lipase maturation factor 1 LMF1, the mitochondrial mRNA pseudouridine synthase RPUSD3, LIM and cysteine-rich domains protein 1, LMCD1. Sperm cryopreservation also caused a significant impact on the embryos at 8 to 10 days of development, but especially in the transition from 10 to 12 days. Overall, our findings provide strong evidence that insemination with cryopreserved spermatozoa poses a major impact in embryo development that may compromise its growth and viability, probably due to modifications in sperm proteins induced by cryopreservation. Identification of specific factors in the spermatozoa causing these changes may improve cryopreservation.

Structure of lipoprotein lipase in complex with GPIHBP1

Lipoprotein lipase (LPL) plays a central role in triglyceride (TG) metabolism. By catalyzing the hydrolysis of TGs present in TG-rich lipoproteins (TRLs), LPL facilitates TG utilization and regulates circulating TG and TRL concentrations. Until very recently, structural information for LPL was limited to homology models, presumably due to the propensity of LPL to unfold and aggregate. By coexpressing LPL with a soluble variant of its accessory protein glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 (GPIHBP1) and with its chaperone protein lipase maturation factor 1 (LMF1), we obtained a stable and homogenous LPL/GPIHBP1 complex that was suitable for structure determination. We report here X-ray crystal structures of human LPL in complex with human GPIHBP1 at 2.5–3.0 Å resolution, including a structure with a novel inhibitor bound to LPL. Binding of the inhibitor resulted in ordering of the LPL lid and lipid-binding regions and thus enabled determination of the first crystal structure of LPL that includes these important regions of the protein. It was assumed for many years that LPL was only active as a homodimer. The structures and additional biochemical data reported here are consistent with a new report that LPL, in complex with GPIHBP1, can be active as a monomeric 1:1 complex. The crystal structures illuminate the structural basis for LPL-mediated TRL lipolysis as well as LPL stabilization and transport by GPIHBP1.