Neurotrophin and neurotrophin receptor expression by cells of the human lamina cribrosa.
OBJECTIVE
To determine whether cells and tissue from the human lamina cribrosa (LC) express neurotrophin and tyrosine kinase (trk) receptor mRNA and protein and whether these cells secrete neurotrophins.


METHODS
Synthesis of cDNA and the reverse transcription-polymerase chain reaction (RT-PCR) were conducted using total RNA obtained from well-characterized cell lines from the human LC and human optic nerve head (ONH) tissue. Immunofluorescent localization and Western blot analysis were used to evaluate neurotrophin and trk protein expression in cells and tissue from the human LC. Immunoassay systems (ELISAs) were used to detect the secretion of neurotrophins.


RESULTS
Two morphologically distinct cell types (LC cells and ONH astrocytes) were isolated and characterized from the human LC. Messenger RNA for each of the neurotrophins, three full-length trk receptors and two truncated trk receptors were detected in both cell types and in human ONH tissue. Protein for the neurotrophins and trk receptors were detected in LC cells, ONH astrocytes, and ONH tissue. Neither cell type expressed mRNA or protein for the low-affinity neurotrophin receptor p75. The secretion of neurotrophins was observed in both cell types.


CONCLUSIONS
Cells from the human LC express mRNA and protein of neurotrophins and trk receptors. In addition, cells from the LC secrete neurotrophins, which suggests that there is paracrine and/or autocrine signaling within the LC. Neurotrophin signaling within this region of the ONH may play important roles in the maintenance of the normal LC and in such diseases as glaucoma.
Lambert
W
W
Department of Pathology and Anatomy, Division of Cell Biology and Genetics, University of North Texas Health Science Center at Fort Worth, 76107, USA. wlambert@hsc.unt.edu
Agarwal
R
R
Howe
W
W
Clark
A F
AF
Wordinger
R J
RJ
D015139:Blotting, Southern; D015153:Blotting, Western; D019208:Brain-Derived Neurotrophic Factor / Q000096:biosynthesis / Q000235:genetics; D002478:Cells, Cultured; D017931:DNA Primers / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D005904:Glial Fibrillary Acidic Protein / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D009414:Nerve Growth Factors / Q000096:biosynthesis / Q000235:genetics*; D009898:Optic Disk / Q000166:cytology / Q000378:metabolism*; D012313:RNA / Q000302:isolation & purification; D012333:RNA, Messenger / Q000096:biosynthesis; D017475:Receptors, Nerve Growth Factor / Q000096:biosynthesis / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D019208:Brain-Derived Neurotrophic Factor; D017931:DNA Primers; D005904:Glial Fibrillary Acidic Protein; D009414:Nerve Growth Factors; D012333:RNA, Messenger; D017475:Receptors, Nerve Growth Factor; D012313:RNA