Identification of the mouse neurochondrin promoter region and the responsible region for cell type specific gene regulation

Changes in the molecular phenotype of nucleus pulposus cells with intervertebral disc aging

Intervertebral disc (IVD) disorder and age-related degeneration are believed to contribute to low back pain. Cell-based therapies represent a promising strategy to treat disc degeneration; however, the cellular and molecular characteristics of disc cells during IVD maturation and aging still remain poorly defined. This study investigated novel molecular markers and their age-related changes in the rat IVD. Affymetrix cDNA microarray analysis was conducted to identify a new set of genes characterizing immature nucleus pulposus (NP) cells. Among these markers, select neuronal-related proteins (Basp1, Ncdn and Nrp-1), transcriptional factor (Brachyury T), and cell surface receptors (CD24, CD90, CD155 and CD221) were confirmed by real-time PCR and immunohistochemical (IHC) staining for differential expression between IVD tissue regions and among various ages (1, 12 and 21 months). NP cells generally possessed higher levels of mRNA or protein expression for all aforementioned markers, with the exception of CD90 in anulus fibrosus (AF) cells. In addition, CD protein (CD24 and CD90) and Brachyury (T) expression in immature disc cells were also confirmed via flow cytometry. Similar to IHC staining, results revealed a higher percentage of immature NP cells expressing CD24 and Brachyury, while higher percentage of immature AF cells was stained positively for CD90. Altogether, this study identifies that tissue-specific gene expression and age-related differential expression of the above markers do exist in immature and aged disc cells. These age-related phenotype changes provide a new insight for a molecular profile that may be used to characterize NP cells for developing cell-based regenerative therapy for IVD regeneration.

Norbin: A promising central nervous system regulator

Norbin, a neurite-outgrowth promoting protein, has been found to interact with and regulate several membrane proteins, including metabotropic glutamate receptor 5 (mGluR5). The disruption of both Norbin alleles leads to early embryonic death between 3.5 and 6.5 day post coitus.1 Forebrain specific Norbin knockout (KO) mice are defective in synaptic plasticity,2 an interesting feature considering that Norbin was initially discovered in the context of chemical-induced long term potentiation (LTP),3 a form of synaptic plasticity extensively studied in the context of learning and memory.4 The behavioral phenotypes associated with Norbin conditional KO suggest reduced mGluR5 function. Because of its fundamental functions, Norbin is emerging as a key neuronal regulator. The aim of the present review is to summarize current knowledge about Norbin while emphasizing its role in the nervous system.

Neurochondrin negatively regulates CaMKII phosphorylation, and nervous system-specific gene disruption results in epileptic seizure

Neurochondrin is a novel cytoplasmic protein and possibly involved in neurite outgrowth, chondrocyte differentiation, and bone metabolism. Our previous trial in disclosing its role by the loss of function in mice failed because of the lethality in utero. In this study, we eliminated the neurochondrin gene expression preferentially in the nervous system by the conditional knockout strategy. Our results showed that neurochondrin is a negative regulator of Ca(2+)/calmodulin-dependent protein kinase II phosphorylation and essential for the spatial learning process but not for the differentiation or neurite outgrowth of the neuron. In addition, the nervous system-specific homozygous gene disruption resulted in epileptic seizure.