Limits...
Semaphorin signaling in vertebrate neural circuit assembly.

Yoshida Y - Front Mol Neurosci (2012)

Bottom Line: The major semaphorin receptors are plexins and neuropilins, however other receptors and co-receptors also mediate signaling by semaphorins.Upon semaphorin binding to their receptors, downstream signaling molecules transduce this event within cells to mediate further events, including alteration of microtubule and actin cytoskeletal dynamics.Here, I review recent studies on semaphorin signaling in vertebrate neural circuit assembly, with the goal of highlighting how this diverse family of cues and receptors imparts exquisite specificity to neural complex connectivity.

View Article: PubMed Central - PubMed

Affiliation: Division of Developmental Biology, Cincinnati Children's Hospital Medical Center Cincinnati, OH, USA.

ABSTRACT
Neural circuit formation requires the coordination of many complex developmental processes. First, neurons project axons over long distances to find their final targets and then establish appropriate connectivity essential for the formation of neuronal circuitry. Growth cones, the leading edges of axons, navigate by interacting with a variety of attractive and repulsive axon guidance cues along their trajectories and at final target regions. In addition to guidance of axons, neuronal polarization, neuronal migration, and dendrite development must be precisely regulated during development to establish proper neural circuitry. Semaphorins consist of a large protein family, which includes secreted and cell surface proteins, and they play important roles in many steps of neural circuit formation. The major semaphorin receptors are plexins and neuropilins, however other receptors and co-receptors also mediate signaling by semaphorins. Upon semaphorin binding to their receptors, downstream signaling molecules transduce this event within cells to mediate further events, including alteration of microtubule and actin cytoskeletal dynamics. Here, I review recent studies on semaphorin signaling in vertebrate neural circuit assembly, with the goal of highlighting how this diverse family of cues and receptors imparts exquisite specificity to neural complex connectivity.

No MeSH data available.


Semaphorins and their receptors (plexins and neuropilins). Semaphorins consist of secreted (class 3), glycosylphosphatidylinositol (GPI)-anchored (class 7), or transmembrane (class 4–6) family members. Neuropilins consist of two transmembrane molecules (Npn1–2), and plexins consist of transmembrane A (1–4), B (1–3), C1, and D1 family members. Most class 3 semaphorins require an obligate neuropilin co-receptor. Sema3E binds to PlexD1 without neuropilins. Class 4 and 5 semaphorins interact with plexinBs. Class 6 semaphorins interact with plexinAs. Sema7A interacts with PlexC1. CUB indicates complement binding. One to seven indicate the interactions between semaphorins and their receptors; 1: class 3 semaphorins and neuropilin1/2, 2: Sema3E and PlexD1, 3: Sema4D and PlexB1/B2 or Sema4C/4G and PlexB1, 4: Sema5A/5B and PlexA1/A3, 5: Sema5A and PlexB3, 6: Sema6A/6B and PlexA2/A3 or Sema6C/6D and PlexA1, 7: Sema7A and PlexC1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3368236&req=5

Figure 1: Semaphorins and their receptors (plexins and neuropilins). Semaphorins consist of secreted (class 3), glycosylphosphatidylinositol (GPI)-anchored (class 7), or transmembrane (class 4–6) family members. Neuropilins consist of two transmembrane molecules (Npn1–2), and plexins consist of transmembrane A (1–4), B (1–3), C1, and D1 family members. Most class 3 semaphorins require an obligate neuropilin co-receptor. Sema3E binds to PlexD1 without neuropilins. Class 4 and 5 semaphorins interact with plexinBs. Class 6 semaphorins interact with plexinAs. Sema7A interacts with PlexC1. CUB indicates complement binding. One to seven indicate the interactions between semaphorins and their receptors; 1: class 3 semaphorins and neuropilin1/2, 2: Sema3E and PlexD1, 3: Sema4D and PlexB1/B2 or Sema4C/4G and PlexB1, 4: Sema5A/5B and PlexA1/A3, 5: Sema5A and PlexB3, 6: Sema6A/6B and PlexA2/A3 or Sema6C/6D and PlexA1, 7: Sema7A and PlexC1.

Mentions: Semaphorins (Semas), which consist of 20 family members in vertebrates, are one of the largest families of guidance cues. Semaphorins include both secreted and membrane-bound proteins, and they serve a variety of roles in the peripheral and central nervous system (PNS and CNS; reviewed in Mann et al., 2007; Tran et al., 2007; Pasterkamp and Giger, 2009). Semaphorins were first characterized as repulsive guidance cues, and later a role in promoting neuronal growth was identified. In vertebrates, semaphorins are subdivided into five subfamilies, including classes 3, 4, 5, 6, and 7 (Figure 1). The major receptors for semaphorins are plexins and neuropilins (Figure 1). Plexins and neuropilins consist of nine and two family members in mammals, respectively. Plexins and neuropilins are subdivided into four classes; plexin (Plex) A1–4, B1–3, C1, and D1, and two classes; neuropilin1–2 (Npn1–2), respectively. Most class 3 semaphorins bind to Npns, and Npns associate with plexinA family members to transduce Sema3 signals across the neuronal plasma membrane (Takahashi et al., 1999; Tamagnone et al., 1999). Sema3E is an exception and directly binds to PlexD1 (Gu et al., 2005). Other interactions between semaphorins and plexins have also been reported, including the interaction between Sema4D and PlexB1 (Tamagnone et al., 1999), between Sema5A and PlexB3 (Artigiani et al., 2004), between Sema7A and PlexC1 (Tamagnone et al., 1999), among Sema6C/6D and PlexA1 (Toyofuku et al., 2004; Yoshida et al., 2006), and among Sema6A/6B and PlexA2/A4 (Suto et al., 2005; Figure 1). Semaphorins also bind to other receptors in addition to plexins and Npns (Tran et al., 2007). For example, class 4 semaphorins signal through two immune system receptors, CD72 and Tim-2 (Kumanogoh et al., 2000, 2002; reviewed in Kikutani and Kumanogoh, 2003; Suzuki et al., 2008; Takamatsu and Kumanogoh, 2012). Another example is that the glycosylphosphatidylinositol (GPI)-anchored Sema7A binds to integrin receptors (Pasterkamp et al., 2003). Several reviews cover work over the last two decades on the roles played by semaphorins in the nervous system (Mann et al., 2007; Tran et al., 2007; Pasterkamp and Giger, 2009), so here I focus on recent studies related to neural circuit assembly.


Semaphorin signaling in vertebrate neural circuit assembly.

Yoshida Y - Front Mol Neurosci (2012)

Semaphorins and their receptors (plexins and neuropilins). Semaphorins consist of secreted (class 3), glycosylphosphatidylinositol (GPI)-anchored (class 7), or transmembrane (class 4–6) family members. Neuropilins consist of two transmembrane molecules (Npn1–2), and plexins consist of transmembrane A (1–4), B (1–3), C1, and D1 family members. Most class 3 semaphorins require an obligate neuropilin co-receptor. Sema3E binds to PlexD1 without neuropilins. Class 4 and 5 semaphorins interact with plexinBs. Class 6 semaphorins interact with plexinAs. Sema7A interacts with PlexC1. CUB indicates complement binding. One to seven indicate the interactions between semaphorins and their receptors; 1: class 3 semaphorins and neuropilin1/2, 2: Sema3E and PlexD1, 3: Sema4D and PlexB1/B2 or Sema4C/4G and PlexB1, 4: Sema5A/5B and PlexA1/A3, 5: Sema5A and PlexB3, 6: Sema6A/6B and PlexA2/A3 or Sema6C/6D and PlexA1, 7: Sema7A and PlexC1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368236&req=5

Figure 1: Semaphorins and their receptors (plexins and neuropilins). Semaphorins consist of secreted (class 3), glycosylphosphatidylinositol (GPI)-anchored (class 7), or transmembrane (class 4–6) family members. Neuropilins consist of two transmembrane molecules (Npn1–2), and plexins consist of transmembrane A (1–4), B (1–3), C1, and D1 family members. Most class 3 semaphorins require an obligate neuropilin co-receptor. Sema3E binds to PlexD1 without neuropilins. Class 4 and 5 semaphorins interact with plexinBs. Class 6 semaphorins interact with plexinAs. Sema7A interacts with PlexC1. CUB indicates complement binding. One to seven indicate the interactions between semaphorins and their receptors; 1: class 3 semaphorins and neuropilin1/2, 2: Sema3E and PlexD1, 3: Sema4D and PlexB1/B2 or Sema4C/4G and PlexB1, 4: Sema5A/5B and PlexA1/A3, 5: Sema5A and PlexB3, 6: Sema6A/6B and PlexA2/A3 or Sema6C/6D and PlexA1, 7: Sema7A and PlexC1.
Mentions: Semaphorins (Semas), which consist of 20 family members in vertebrates, are one of the largest families of guidance cues. Semaphorins include both secreted and membrane-bound proteins, and they serve a variety of roles in the peripheral and central nervous system (PNS and CNS; reviewed in Mann et al., 2007; Tran et al., 2007; Pasterkamp and Giger, 2009). Semaphorins were first characterized as repulsive guidance cues, and later a role in promoting neuronal growth was identified. In vertebrates, semaphorins are subdivided into five subfamilies, including classes 3, 4, 5, 6, and 7 (Figure 1). The major receptors for semaphorins are plexins and neuropilins (Figure 1). Plexins and neuropilins consist of nine and two family members in mammals, respectively. Plexins and neuropilins are subdivided into four classes; plexin (Plex) A1–4, B1–3, C1, and D1, and two classes; neuropilin1–2 (Npn1–2), respectively. Most class 3 semaphorins bind to Npns, and Npns associate with plexinA family members to transduce Sema3 signals across the neuronal plasma membrane (Takahashi et al., 1999; Tamagnone et al., 1999). Sema3E is an exception and directly binds to PlexD1 (Gu et al., 2005). Other interactions between semaphorins and plexins have also been reported, including the interaction between Sema4D and PlexB1 (Tamagnone et al., 1999), between Sema5A and PlexB3 (Artigiani et al., 2004), between Sema7A and PlexC1 (Tamagnone et al., 1999), among Sema6C/6D and PlexA1 (Toyofuku et al., 2004; Yoshida et al., 2006), and among Sema6A/6B and PlexA2/A4 (Suto et al., 2005; Figure 1). Semaphorins also bind to other receptors in addition to plexins and Npns (Tran et al., 2007). For example, class 4 semaphorins signal through two immune system receptors, CD72 and Tim-2 (Kumanogoh et al., 2000, 2002; reviewed in Kikutani and Kumanogoh, 2003; Suzuki et al., 2008; Takamatsu and Kumanogoh, 2012). Another example is that the glycosylphosphatidylinositol (GPI)-anchored Sema7A binds to integrin receptors (Pasterkamp et al., 2003). Several reviews cover work over the last two decades on the roles played by semaphorins in the nervous system (Mann et al., 2007; Tran et al., 2007; Pasterkamp and Giger, 2009), so here I focus on recent studies related to neural circuit assembly.

Bottom Line: The major semaphorin receptors are plexins and neuropilins, however other receptors and co-receptors also mediate signaling by semaphorins.Upon semaphorin binding to their receptors, downstream signaling molecules transduce this event within cells to mediate further events, including alteration of microtubule and actin cytoskeletal dynamics.Here, I review recent studies on semaphorin signaling in vertebrate neural circuit assembly, with the goal of highlighting how this diverse family of cues and receptors imparts exquisite specificity to neural complex connectivity.

View Article: PubMed Central - PubMed

Affiliation: Division of Developmental Biology, Cincinnati Children's Hospital Medical Center Cincinnati, OH, USA.

ABSTRACT
Neural circuit formation requires the coordination of many complex developmental processes. First, neurons project axons over long distances to find their final targets and then establish appropriate connectivity essential for the formation of neuronal circuitry. Growth cones, the leading edges of axons, navigate by interacting with a variety of attractive and repulsive axon guidance cues along their trajectories and at final target regions. In addition to guidance of axons, neuronal polarization, neuronal migration, and dendrite development must be precisely regulated during development to establish proper neural circuitry. Semaphorins consist of a large protein family, which includes secreted and cell surface proteins, and they play important roles in many steps of neural circuit formation. The major semaphorin receptors are plexins and neuropilins, however other receptors and co-receptors also mediate signaling by semaphorins. Upon semaphorin binding to their receptors, downstream signaling molecules transduce this event within cells to mediate further events, including alteration of microtubule and actin cytoskeletal dynamics. Here, I review recent studies on semaphorin signaling in vertebrate neural circuit assembly, with the goal of highlighting how this diverse family of cues and receptors imparts exquisite specificity to neural complex connectivity.

No MeSH data available.