Effect of Lactoferrin on the Expression Profiles of Long Non-coding RNA during Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells.

Lactoferrin (LF) has demonstrated stimulation of osteogenic differentiation of mesenchymal stem cells (MSCs). Long non-coding RNAs (lncRNAs) participate in regulating the osteogenic differentiation processes. However, the impact of LF on lncRNA expression in MSC osteogenic differentiation is poorly understood. Our aim was to investigate the effects of LF on lncRNAs expression profiles, during osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs), by RNA sequencing. A total number of 1331 putative lncRNAs were identified in rBMSCs during osteogenic differentiation in the study. LF influenced the expression of 120 lncRNAs (differentially expressed lncRNAs [DELs], Fold change > 1.5 or < -1.5; p < 0.05) in rBMSCs on day 14 of osteogenic differentiation, consisted of 60 upregulated and 60 down-regulated. Furthermore, the potential functions of DELs were of prediction by searching their target cis- and trans-regulated protein-coding genes. The bioinformatic analysis of DELs target gene revealed that LF led to the disfunction of transforming growth factor beta stimulus (TGF-ß) and positive regulation of I-κappa B kinase/NF-κappa B signaling pathway, which may relate to osteogenic differentiation of rBMSCs. Our work is the first profiling of lncRNA in osteogenic differentiation of rBMSCs induced by LF, and provides valuable insights into the potential mechanisms for LF promoting osteogenic activity.

[Effect of pH on circular dichroism and Raman spectroscopy of secondary structure of beta-casein from Chinese human milk].

To obtain a structural basis for the beta-casein in Chinese human milk, structural transitions of the beta-casein in response to variation of pH were investigated using Raman and circular dichroism (CD) spectroscopy. Both methods indicated that the secondary structures of beta-casein in the solution were induced by the pH. Secondary structural analysis of beta-casein by CD spectroscopy yielded 0.5%-2% alpha-helical, 16%-18% beta-sheet, 30%-34% beta-turn and 49%-51% random coil contents. Another result was that as pH increases, these structures change. Several distinct transitions were observed by circular dichroism in alpha-helix at pH 8 and pH 10. Raman spectrum also showed random coil as the major secondary structure in native beta-casein, for the characteristic band of the beta-casein amide I was at 1662 cm(-1): Calculations from I850/I830 suggested that the tyrosine residues of beta-casein tended to "exposure". CD and Raman spectra both showed that at neutral and alkaline pH the beta-casein existed predominantly in random coil conformation, and the proportion of alpha-helix was higher at pH 8 than under other pH conditions. Over the range of pH studied, the sheet and turn areas remained relatively constant, and in the condition of pH 8, the content of alpha-helical was higher than in the other pH conditions.

[Comparison of the function and conformation of human ß-casein and bovine ß-casein by spectroscopic study].

ß-Casein was the main component of human milk casein, but the content of ß-casein in the bovine milk was less. The difference in ß-casein content of the two samples was one of the reasons why human milk is more digestible than bovine milk. Studying the differences of structure and function in human and bovine milk ß-casein can help us develop a new human milk simulated infant formula which will be more suitable for the infant gut. The UV spectrophotometer was used to study the solubility, sulfhydryl and emulsification of human milk ß-casein and bovine milk ß-casein, Fluorescence spectroscopy and the infrared spectroscopy were used to study the structural characteristics of human milk ß-casein and bovine milk ß-casein. The two samples shared a similar isoelectric point (pH 4.0~5.0), the solubility of human milk ß-casein (10.83%) was lower than which in bovine milk ß-casein (11.83%) near the pI, while it was higher when it deviated the pI. The emulsion ability (110~140 m2 · g(-1)) of human milk ß-casein was higher than that in bovine milk ß-casein (70~130 m2 · g(-1)) and surface sulfhydryl group (SH) of two kinds of milk protein were similar [(18.47±0.08) µmol · g(-1) and (18.67±0.17) µmol · g(-1)]. The total sulfhydryl group [(47.46±0.23) µmol · g(-1)] in bovine milk ß-casein was more than that in human milk ß-casein [(26.17±0.12) µmol · g(-1)]. Functional groups in two samples were similar and they both contained beta sheet, human milk ß-casein had less H-bond and internal hydrophobic than bovine milk ß-casein. The results showed that the two samples had similar functional groups, while human milk ß-casein had much less secondary structure such as α-helix and ß-sheet, a looser tertiary structure and a better interfacial activity.