The goal of this proposal is to determine the molecular signals that instruct the fate specification and the lineage-specific development of corticospinal motor neurons (CSMN). These neurons are a clinically relevant population that, in humans, selectively dies in neurodegenerative diseases, including Amyotrophic Lateral Sclerosis (ALS), Hereditary Spastic Paraplegia (HSP), and Primary Lateral Sclerosis (PLS). They are also the cells permanently injured and responsible for paralysis in spinal cord injury (SCI). In the nervous system, studies aimed at investigating the molecular controls over birth, survival and connectivity of individual neuron types have been notoriously difficult, owing to the astonishing cellular heterogeneity of the tissue, combined with the inability to distinguish and purify one neuron type in isolation from others. In my postdoctoral work, I addressed this issue directly in the cortex, and have identified and begun to functionally characterize the first series of genes that in a combinatorial fashion uniquely identify CSMN as this neuron type develops [1]. Most relevant to the present proposal, we discovered that the transcription factor Fezf2 is a "master gene" that is both necessary for the birth of CSMN (i.e. CSMN are absent from the cortex of Fezf2-/- mice), and is at least in part sufficient to instruct the fate-specification of cortical progenitors to CSMN (i.e. elevated levels of Fezf2 can induce a "fate-switch" in progenitors destined to form upper layer neurons towards forming CSMN and deep layer neurons) [2]. Here, I build on this prior work and on new data from my own laboratory to directly investigate the central questions of this proposal: (1): What are the molecular signals that instruct the fate-specification and early development of cortical progenitors into CSMN? (Aim 1 and Aim 2) (2): Do postmitotic neurons of a different cortical type maintain the ability to generate CSMN in response to Fezf2 or, rather, are neuron lineage-specification decisions made and only modulated at the progenitor stage? (Aim 3) We present prior published work and substantial new data that support the feasibility of these experiments, and the direct relevance of the results to the development of novel therapeutic strategies to replace CSMN in neurodegenerative and traumatic diseases of the corticospinal circuitry.

Public Health Relevance

Different neurodegenerative diseases of the CNS are typically characterized by the progressive death of specific neuron types. Corticospinal motor neuron (CSMN) degeneration and injury is a key component of motor neuron disease (including ALS), and of spinal cord injury. Here we propose to determine the molecular signals that instruct the birth of this clinically relevant neuron type, and to investigate the extent to which CSMN can be regenerated for therapeutic application.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS062849-06
Application #
8432878
Study Section
Neurogenesis and Cell Fate Study Section (NCF)
Program Officer
Riddle, Robert D
Project Start
2009-03-01
Project End
2015-02-28
Budget Start
2013-03-01
Budget End
2015-02-28
Support Year
6
Fiscal Year
2013
Total Cost
$349,614
Indirect Cost
$142,742
Name
Harvard University
Department
Anatomy/Cell Biology
Type
Schools of Arts and Sciences
DUNS #
082359691
City
Cambridge
State
MA
Country
United States
Zip Code
02138
Arlotta, Paola; Berninger, Benedikt (2014) Brains in metamorphosis: reprogramming cell identity within the central nervous system. Curr Opin Neurobiol 27:208-14
Lodato, Simona; Molyneaux, Bradley J; Zuccaro, Emanuela et al. (2014) Gene co-regulation by Fezf2 selects neurotransmitter identity and connectivity of corticospinal neurons. Nat Neurosci 17:1046-54
Amamoto, Ryoji; Arlotta, Paola (2014) Development-inspired reprogramming of the mammalian central nervous system. Science 343:1239882
Tomassy, Giulio Srubek; Berger, Daniel R; Chen, Hsu-Hsin et al. (2014) Distinct profiles of myelin distribution along single axons of pyramidal neurons in the neocortex. Science 344:319-24
Rouaux, Caroline; Arlotta, Paola (2013) Direct lineage reprogramming of post-mitotic callosal neurons into corticofugal neurons in vivo. Nat Cell Biol 15:214-21
Lodato, Simona; Rouaux, Caroline; Quast, Kathleen B et al. (2011) Excitatory projection neuron subtypes control the distribution of local inhibitory interneurons in the cerebral cortex. Neuron 69:763-79
Lodato, Simona; Tomassy, Giulio Srubek; De Leonibus, Elvira et al. (2011) Loss of COUP-TFI alters the balance between caudal ganglionic eminence- and medial ganglionic eminence-derived cortical interneurons and results in resistance to epilepsy. J Neurosci 31:4650-62
Shoemaker, Lorelei D; Arlotta, Paola (2010) Untangling the cortex: Advances in understanding specification and differentiation of corticospinal motor neurons. Bioessays 32:197-206
Rouaux, Caroline; Arlotta, Paola (2010) Fezf2 directs the differentiation of corticofugal neurons from striatal progenitors in vivo. Nat Neurosci 13:1345-7
Tomassy, Giulio Srubek; Lodato, Simona; Trayes-Gibson, Zachary et al. (2010) Development and regeneration of projection neuron subtypes of the cerebral cortex. Sci Prog 93:151-69