Tang Minghui, Mao Jeremy J
Tissue Engineering Laboratory, Rm 237, University of Illinois at Chicago MC 841, 801 South Paulina Street, Chicago, IL 60612-7211, USA.
Cell Tissue Res. 2006 Jun;324(3):467-74. doi: 10.1007/s00441-005-0143-7. Epub 2006 Mar 7.
Recent data have shown that the proliferation and differentiation of the cranial base growth plate (CBGP) chondrocytes are modulated by mechanical stresses. However, little is known about the expression of genes and matrix molecules in the CBGP during development or under mechanical stresses. The objective of the present study was to determine whether several cartilage- and bone-related molecules are expressed in the CBGP and whether their expression is modulated by cyclic loading. The CBGP of normal 8-day-old rats (n=8) were isolated immediately after death, followed by extraction of total RNA and reverse transcription/polymerase chain reaction (RT-PCR) analysis. All studied genes, including type II and X collagens, biglycan, versican, osteocalcin, osteopontin, and fetal liver kinase 1, were expressed in the CBGP with a reproducible absence of decorin mRNA. In age- and sex-matched rats (n=10), exogenous cyclic forces were applied to the maxilla at 500 mN and 4 Hz for 20 min/day over 2 days, followed by RNA isolation and RT-PCR analysis. This exogenous cyclic loading consistently induced the expression of the decorin gene, which was non-detectable, by the current RT-PCR approach, in control neonatal CBGPs without loading. Immunolocalization of several of the above-studied gene products demonstrated their remarkable site-specific expression. Decorin proteoglycan was primarily expressed in the perichondrium instead of various cartilage growth zones, especially upon mechanical loading. These findings serve as baseline data for the expression of several genes and gene products in the neonatal CBGP. Mechanical modulation of decorin expression is consistent with recent reports of its susceptibility to mechanical loading in several connective tissues.
近期数据表明，颅底生长板（CBGP）软骨细胞的增殖和分化受机械应力调节。然而，关于CBGP在发育过程中或机械应力作用下基因和基质分子的表达情况，人们了解甚少。本研究的目的是确定几种与软骨和骨相关的分子是否在CBGP中表达，以及它们的表达是否受周期性加载的调节。正常8日龄大鼠（n = 8）死后立即分离出CBGP，随后提取总RNA并进行逆转录/聚合酶链反应（RT-PCR）分析。所有研究的基因，包括II型和X型胶原蛋白、双糖链蛋白聚糖、多功能蛋白聚糖、骨钙素、骨桥蛋白和胎儿肝激酶1，均在CBGP中表达，而核心蛋白聚糖mRNA未表达，且具有可重复性。在年龄和性别匹配的大鼠（n = 10）中，以500 mN和4 Hz的频率对上颌施加外源周期性力，每天20分钟，持续2天，随后进行RNA分离和RT-PCR分析。这种外源周期性加载持续诱导核心蛋白聚糖基因的表达，而在未加载的对照新生CBGP中，通过当前的RT-PCR方法检测不到该基因。上述几种研究基因产物的免疫定位显示了它们显著的位点特异性表达。核心蛋白聚糖蛋白聚糖主要表达于软骨膜而非各种软骨生长区，尤其是在机械加载时。这些发现为新生CBGP中几种基因和基因产物的表达提供了基线数据。核心蛋白聚糖表达的机械调节与近期关于其在几种结缔组织中对机械加载敏感性的报道一致。
