Differentially expressed genes in the lens of mimecan-null mice

[摘要] Purpose: Members of the small leucine-rich proteoglycans (SLRP) genefamily are essential for normal collagen fibrillogenesis in variousconnective tissues and important regulators of cellular growth,differentiation, and tissue repair. Mimecan is a member of this genefamily and is expressed in many connective tissues. We have previouslyreported that knockout of the mouse mimecan gene results in abnormalcollagen fibrillogenesis, mainly in the cornea and skin. During thecourse of our studies on biological roles of mimecan in the eye, wefound that this gene is expressed in the mouse lens. Here, we sought toidentify gene expression changes in the lens that are associated withthe absence of mimecan.Methods: Reverse transcription-polymerase chain reactionamplification (RT-PCR), in situ hybridization (ISH), andimmunohistochemistry (IHC) were used to determine mimecan expression inhuman and mouse eyes. Microarray hybridization was used to determinegene expression differences between lenses isolated from mimecan-nulland wild type mice. Relative quantitative RT-PCR was used to verify theexpression levels of a subset of the identified genes.Results: By ISH and IHC, mimecan mRNA was detected in cornea andlens at embryonic day 16.5 (E16.5) and postnatal day 10 (P10) mouseeyes. By RT-PCR, mimecan mRNA was detected in human cornea, lens, iris,and retina. In mimecan-null mice lenses, microarray analysis of 5,002mouse genes demonstrated a more than two fold increase in expression of65 genes and a more than two fold decrease in expression of 76 genes.Among genes with increased expression were cell adhesion molecules,G-protein coupled receptors, intracellular signaling molecules, genesinvolved in protein biosynthesis and degradation, and genes involved inimmune function. Decreased expression was found in extracellular matrixmolecules, calcium binding and transporting proteins, and genes knownfor their roles in regulating cellular motility. Intriguingly, decreasedgene expression was observed with two SLRP family members, biglycan andcondroadherin, as well as with several stress-response proteins,including γA-crystallin, hemoglobin alpha 1, and metallothionein1. Quantitative RT-PCR confirmed changes in expression of 12 genesselected from the arrays.Conclusions: In this report we present the first demonstration thatmimecan is constitutively expressed in the vertebrate lens. The resultsfrom gene expression profiling reveal the ability of mimecan toinfluence expression of biglycan and chondroadherin, thereby indicatingpossible novel regulatory interactions between these SLRP familymembers. As with mimecan, the expression of chondroadrein in vertebratelens has not been reported previously. Our results provide insight intothe function of mimecan in the lens and enable further characterizationof molecular mechanisms by which this protein exerts its biologicalroles.

[学科分类] 生物化学/生物物理