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Chang-Lin Lu

Publications and source records attributed to Chang-Lin Lu.

12 recordsLinked to original sources
PubMed2006

Interaction of SH2-Bbeta with RET is involved in signaling of GDNF-induced neurite outgrowth.

RET receptor signalling is essential for glial-cell-line-derived neurotrophic factor (GDNF)-induced survival and differentiation of various neurons such as mesencephalic neurons. To identify proteins that mediate RET-dependent signaling, yeast two-hybrid screening was performed with the intracellular domain of RET as bait. We identified a new interaction between RET and the adapter protein SH2-Bbeta. Upon GDNF stimulation of PC12-GFRalpha1-RET cells (that stably overexpress GDNF receptor alpha1 and RET), wild-type SH2-Bbeta co-immunoprecipitated with RET, whereas the dominant-negative SH2-Bbeta mutant R555E did not. RET interacted with endogenous SH2-Bbeta both in PC12-GFRalpha1-RET cells and in rat tissues. Mutagenesis analysis revealed that Tyr981 within the intracellular domain of RET was crucial for the interaction with SH2-Bbeta. Morphological evidence showed that SH2-Bbeta and RET colocalized in mesencephalic neurons. Furthermore, functional analysis indicated that overexpression of SH2-Bbeta facilitated GDNF-induced neurite outgrowth in both PC12-GFRalpha1-RET cells and cultured mesencephalic neurons, whereas the mutant R555E inhibited the effect. Moreover, inhibition of SH2-Bbeta expression by RNA interference caused a significant decrease of GDNF-induced neuronal differentiation in PC12-GFRalpha1-RET cells. Taken together, our results suggest that SH2-Bbeta is a new signaling molecule involved in GDNF-induced neurite outgrowth.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Olfactory ensheathing cells genetically modified to secrete GDNF to promote spinal cord repair.

Olfactory ensheathing cell (OEC) transplantation has emerged as a very promising therapy for spinal cord repair. In this study, we tested the ability of genetically modified OECs to secrete high levels of glial cell line-derived neurotrophic factor (GDNF) to promote spinal cord repair. The GDNF gene was transduced into OECs using a retroviral-based system. The engineered OECs were first characterized by their ability to express and secrete biologically active GDNF in vitro. After implantation into the spinal cord of adult rats with complete spinal cord transection, OEC survival and GDNF production were examined. The locomotor functions of animals were assessed and axon regeneration was evaluated at the morphological level. To our knowledge, we report for the first time that the genetically modified OECs are capable of producing GDNF in vivo to significantly improve recovery after spinal cord injury (SCI). This work combined the outgrowth-promoting property of OECs with the neuroprotective effects of the additionally overexpressed neurotrophic factors and opens new avenues for the treatment of SCI.

Animals↗
PubMed2003

Identification of the key amino acids of glial cell line-derived neurotrophic factor family receptor alpha1 involved in its biological function.

Glial cell line-derived neurotrophic factor (GDNF) plays a critical role in neurodevelopment and survival of midbrain dopaminergic and spinal motor neurons in vitro and in vivo. The biological actions of GDNF are mediated by a two-receptor complex consisting of a glycosylphosphatidylinositol-linked cell surface molecule, the GDNF family receptor alpha1 (GFRalpha1), and receptor protein tyrosine kinase Ret. Although structural analysis of GDNF has been extensively examined, less is known about the structural basis of GFRalpha1 function. In this study, based on evolutionary trace method and relative solvent accessibility prediction of residues, a set of trace residues that are solvent-accessible was selected for site-directed mutagenesis. A series of GFRalpha1 mutations was made, and PC12 cell lines stably expressing different GFRalpha1 mutants were generated. According to the survival and differentiation responses of these stable PC12 cells upon GDNF stimulation and the GDNF-GFRalpha1-Ret interaction assay, residues 152NN153, Arg259, and 316SNS318 in the GFRalpha1 central region were found to be critical for GFRalpha1 binding to GDNF and eliciting downstream signal transduction. The single mutation R259A in the GFRalpha1 molecule simultaneously lost its binding ability to GDNF and Ret. However N152A/N153A or S316A/N317A/S318A mutation in the GFRalpha1 molecule still retained the ability to bind with Ret. These findings suggest that distinct structural elements in GFRalpha1 may be involved in binding to GDNF and Ret.

Amino Acid Substitution↗
PubMed2003

[Effect of tumor necrosis factor-alpha on differentiation of mesencephalic neural stem cells and proliferation of oligodendrocytes in the rat].

To observe the influence of tumor necrosis factor-alpha (TNF-alpha) on differentiation of rat mesencephalic neural stem cells (NSCs), the numbers of neurons, astrocytes and oligodendrocytes generated from NSCs were analyzed after differentiation for 3 days by using immunocytochemistry technique. The results show that: (1) TNF-alpha enhanced the proportions of neurons and oligodendrocytes in progeny of NSCs; and (2) TNF-alpha induced the proliferation of oligodendrocytes derived from NSCs, but the proliferation of astrocytes was not influenced by TNF-alpha. We conclude that the TNF-alpha could influence the application of NSCs.

Animals↗
PubMed2003

A structure-function analysis of glial cell-line-derived neurotrophic factor receptor alpha1.

The GFRalpha1 cDNA was amplified by RT-PCR from fetal rat hippocampus. The soluble recombinant GFRalpha1 and its mutants were obtained from an Escherichia coli expression system. The biological activity of soluble GFRalpha1 and its mutants were evaluated in PC12 cells. The results suggest that the central domain of GFRalpha1 is a crucial determinant for ligand binding. This established a solid basis for further study to find the key amino acid mediating the binding of GDNF and GFRalpha1.

Amino Acid Sequence↗
PubMed2002

[Progress of monoaminergic receptor investigation on depression].

It is widely accepted that monoamine transmitters are playing an important role in the progress of depression. The functions of monoamine transmitters and their receptors change profoundly during depression and its treatment. This paper is attempted to review the new progress of investigation into serotonin receptors, adrenoceptors and dopamine receptors related with depression mechanism respectively.

Biogenic Monoamines↗
PubMed2000

A Structure-function Analysis of Human GDNF.

The glial cell line-derived neurotrophic factor(GDNF) plays a very important role in the regeneration of the nervous system. Based on the results of the X-ray structure analysis of rat GDNF, human GDNF gene was modified with deletion and insertion mutagenesis by using PCR methods. The various mutants were all highly expressed in E.coli. The recombinant proteins were purified and their survival-promoting activities were determined by using cultures of the spinal cord neurons of embryonic mouse. The results showed that the "cystine knot motif" was critical for the maintenance of GDNF structure the alpha-helix, finger 1 and finger 2 region were critical for GDNF neurotrophic activity and the N-terminus of human GDNF was not essential for its biological functions.

Journal Article↗
PubMed2000

High Expression of Human Persephin in Insect Cells.

The human persephin (PSP) was expressed in Tn-5B1-4 insect cells using the Bac to Bac baculovirus expression system. The expressed product amounted for 20% of total cellular soluble proteins. The expressed product was purified by Ni(2+) affinity chromatography and the activity assays showed that it could significantly prolong the survival of spinal cord neurons.

Journal Article↗
PubMed1999

Cloning of Human Glial Neurotrophic Factor and Its High Expression in Insect Cells.

The human glial cell derived neurotrophic factor (GDNF) was expressed in Tn-5B1-4 insect cells using the Bac to Bac baculovirus expression system, accounting for 30% of total cellular soluble proteins. The expressed product was purified by affinity chromatography and the activity assays showed that it could significantly promote the survival of dopaminergic neurons. The study can be the basis for further structural-functional analysis of GDNF.

Journal Article↗
PubMed1999

The Human Recombinant GDNF and Study of Its Biological Activity.

The cDNA encoding the mature human glial cell derived neurotrophic factor(GDNF) was isolated by using RT-PCR method from total RNA extracted of fetal human brain. The expression plasmid pET-GDNF was constructed by inserting GDNF cDNA into plasmid pET-28a(+) containing T7 promoter and transformed into E.coli BL21(DE3). An expression strain BLGDNF was selected. SDS-PAGE analysis revealed that the human GDNF protein was highly expressed and accumulated up to above 30% of the total bacterial proteins in the form of inclusion body after the induction. The antibody to GDNF was prepared by immunization of rat using purified GDNF protein. Purified and refolded GDNF protein could significantly promote the survival of dopaminergic neurons.

Journal Article↗
PubMed1996

A Structure-function Analysis of the Human Ciliary Neurotrophic Factor.

The ciliary neurotrophic factor (CNTF) plays a very important role in the development and regeneration of the nervous system. In this study, the prediction of secondary structure and the hydrophobicity analysis of human CNTF were performed according to the amino acid sequence deduced from the nucleotide sequence of the cDNA. Based on the results of the prediction of structure, the human CNTF gene was modified by insertion and deletion mutagenesis. The various mutants were all highly expressed in E. coli. The recombinant proteins were purified from bacterial via DEAE A-50 and Sephacryl S-200 chromatography, and their survival-promoting activities were determined by using cultures of the dorsal root ganglion neurons of embryonic chick. The results showed that the alpha-helixes in CNTF were critical for the biological activity and the flexible C-terminus of human CNTF was not essential. Our data also indicated that the middle and the tail part of the D-helix might play crucial roles in the biological functions of CNTF.

Journal Article↗