FoxP2 is a Parvocellular-Specific Transcription Factor in the Visual Thalamus of Monkeys and Ferrets

Abstract

Although the parallel visual pathways are a fundamental basis of visual processing, our knowledge of their molecular properties is still limited. Here, we uncovered a parvocellular-specific molecule in the dorsal lateral geniculate nucleus (dLGN) of higher mammals. We found that FoxP2 transcription factor was specifically expressed in X cells of the adult ferret dLGN. Interestingly, FoxP2 was also specifically expressed in parvocellular layers 3-6 of the dLGN of adult old world monkeys, providing new evidence for a homology between X cells in the ferret dLGN and parvocellular cells in the monkey dLGN. Furthermore, this expression pattern was established as early as gestation day 140 in the embryonic monkey dLGN, suggesting that parvocellular specification has already occurred when the cytoarchitectonic dLGN layers are formed. Our results should help in gaining a fundamental understanding of the development, evolution, and function of the parallel visual pathways, which are especially prominent in higher mammals.

Diverse Visual Features Encoded in Mouse Lateral Geniculate Nucleus

“…Chondroitin sulfate proteoglycans are reported as specific to the magnocellular layers of the monkey LGN and the “Y” (sometimes called “A”) layers of the cat LGN (Murray et al, 2008). Also, the transcription factor FoxP2 is specific to the parvocellular layers of the marmoset (Mashiko et al, 2012) and macaque LGN and X cells in carnivores (Iwai et al, 2012). We stained the mouse LGN for these markers and found that, whereas many LGN cells expressed CSPG and Foxp2 (Fig 8 J, K), neither marker displayed any obvious laminar or overt regional biases.…”

In vivo genetic manipulation of cortical progenitors in gyrencephalic carnivores using in utero electroporation

“…Recently, several groups including us have reported molecules expressed in the structures mentioned above that are unique to higher mammals (Kawasaki et al, 2004; Murray et al, 2008; Johnson et al, 2009; Yamamori, 2011; Bernard et al, 2012; Iwai et al, 2012). For example, we uncovered that the Forkhead transcription factor FoxP2 was selectively expressed in the parvocellular pathway in the dLGN of ferrets and monkeys (Iwai et al, 2012).…”

“…For example, we uncovered that the Forkhead transcription factor FoxP2 was selectively expressed in the parvocellular pathway in the dLGN of ferrets and monkeys (Iwai et al, 2012). Furthermore, recent studies provided lists of genes expressed in the VZ and the SVZ of mice and various cortical regions in monkeys (Ayoub et al, 2011; Bernard et al, 2012).…”

“…Ferrets were maintained as described previously (Kawasaki et al, 2004; Iwai and Kawasaki, 2009; Iwai et al, 2012; Kawasaki et al, 2012). The day of birth was counted as postnatal day 0 (P0).…”

A Molecular Genetic Perspective on Speech and Language

“…FOXP2 has a particularly deep evolutionary history, with versions of the gene described in many different vertebrate species, including monkeys (Takahashi et al, 2008), ferrets (Iwai et al, 2013), mice (Ferland, Cherry, Preware, Morrisey, & Walsh, 2003;Lai, Gerrelli, Monaco, Fisher, & Copp, 2003), rats (Takahashi, Liu, Hirokawa, & Takahashi, 2003), bats (Li, Wang, Rossiter, Jones, & Zhang, 2007), birds (Haesler et al, 2004;Teramitsu et al, 2004), reptiles (Haesler et al, 2004), and fish (Bonkowsky et al, 2008). Researchers have investigated neural expression patterns for most of these species, determining where and when the gene is transcribed and/or translated in developing and mature brain tissue.…”