Neurotrophin-3 induced by tri-iodothyronine in cerebellar granule cells promotes Purkinje cell differentiation.
Thyroid hormones play an important role in brain development, but the mechanism(s) by which triiodothyronine (T3) mediates neuronal differentiation is poorly understood. Here we demonstrate that T3 regulates the neurotrophic factor, neurotrophin-3 (NT-3), in developing rat cerebellar granule cells both in cell culture and in vivo. In situ hybridization experiments showed that developing Purkinje cells do not express NT-3 mRNA but do express trkC, the putative neuronal receptor for NT-3. Addition of recombinant NT-3 to cerebellar cultures from embryonic rat brain induces hypertrophy and neurite sprouting of Purkinje cells, and upregulates the mRNA encoding the calcium-binding protein, calbindin-28 kD. The present study demonstrates a novel interaction between cerebellar granule neurons and developing Purkinje cells in which NT-3 induced by T3 in the granule cells promotes Purkinje cell differentiation.
Lindholm
D
D
Department of Neurochemistry, Max Planck Institute for Psychiatry, Martinsried Munich, Federal Republic of Germany.
Castrén
E
E
Tsoulfas
P
P
Kolbeck
R
R
Berzaghi
M da P
Mda P
Leingärtner
A
A
Heisenberg
C P
CP
Tessarollo
L
L
Parada
L F
LF
Thoenen
H
H
Tesarollo
L
L
D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007037:Hypothyroidism / Q000378:metabolism; D017403:In Situ Hybridization; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D009414:Nerve Growth Factors / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D020933:Neurotrophin 3; D011689:Purkinje Cells / Q000166:cytology* / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020812:Receptor, trkC; D014284:Triiodothyronine / Q000494:pharmacology*
D008562:Membrane Glycoproteins; D009414:Nerve Growth Factors; D020933:Neurotrophin 3; D012333:RNA, Messenger; D014284:Triiodothyronine; D020812:Receptor, trkC