Shank protein

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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Chromosome 22q13 deletion syndrome (22q13DS) is a neurobehavioral syndrome marked by neonatal hyptonia, global developmental delay, and [[Autism|autism spectrum disorder]] features.<ref name="Durand"/> The SHANK3 gene is located within this region of chromosome 22. Studies have revealed that point mutations in SHANK3 can produce the entirety of neurodevelopmental symptoms associated with 22q13DS, accounting for 1% of autism cases.<ref name="Garber">PMID: 17626859</ref> At the molecular level, disruption of the full length Shank3 protein results in reductions in AMPA receptor mediated transmission and spine remodeling.<ref name="Bozdagi"/> Shank3 heterozygous mice, who are haploinsufficient for the Shank3 gene display less social sniffing and emitted fewer ultrasonic vocalizations during interactions with estrus female. Further, knockout mice of Shank have a decreased spine number, a diminished PSD size, decreased levels of GKAP and Homer, and reduced synaptic transmission. Interestingly, overexpression of SHANK3 may also result in an ASD, supporting the hypothesis that Autism is caused by improper Excitatory/Inhibitory neuronal ratios in the brain.<ref name="Bozdagi"/> Measurements of broad miRNA expression levels in Autism patients uncovered dysregulated miRNAs for genes like that of [[MeCP2]], the cause of Rett Syndrome, [[Neurexin-Neuroligin Interaction|NRXN-1]], a gene implicated in ASDs, and Shank3, validating Shank3’s role in autism.<ref>PMID:18563458</ref> Due to the marked reduction in AMPA mediated transmission in Shank3 mutants, compounds that enhance AMPA transmission (AMPAkinses) as potential [[Pharmaceutical Drugs|therapeutic approaches]] to treating some ASDs.<ref name="Bozdagi"/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Chromosome 22q13 deletion syndrome (22q13DS) is a neurobehavioral syndrome marked by neonatal hyptonia, global developmental delay, and [[Autism|autism spectrum disorder]] features.<ref name="Durand"/> The SHANK3 gene is located within this region of chromosome 22. Studies have revealed that point mutations in SHANK3 can produce the entirety of neurodevelopmental symptoms associated with 22q13DS, accounting for 1% of autism cases.<ref name="Garber">PMID: 17626859</ref> At the molecular level, disruption of the full length Shank3 protein results in reductions in AMPA receptor mediated transmission and spine remodeling.<ref name="Bozdagi"/> Shank3 heterozygous mice, who are haploinsufficient for the Shank3 gene display less social sniffing and emitted fewer ultrasonic vocalizations during interactions with estrus female. Further, knockout mice of Shank have a decreased spine number, a diminished PSD size, decreased levels of GKAP and Homer, and reduced synaptic transmission. Interestingly, overexpression of SHANK3 may also result in an ASD, supporting the hypothesis that Autism is caused by improper Excitatory/Inhibitory neuronal ratios in the brain.<ref name="Bozdagi"/> Measurements of broad miRNA expression levels in Autism patients uncovered dysregulated miRNAs for genes like that of [[MeCP2]], the cause of Rett Syndrome, [[Neurexin-Neuroligin Interaction|NRXN-1]], a gene implicated in ASDs, and Shank3, validating Shank3’s role in autism.<ref>PMID:18563458</ref> Due to the marked reduction in AMPA mediated transmission in Shank3 mutants, compounds that enhance AMPA transmission (AMPAkinses) as potential [[Pharmaceutical Drugs|therapeutic approaches]] to treating some ASDs.<ref name="Bozdagi"/>
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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;BetaPIX belongs to a group of guanine nucleotide exchange factors used by Rho GTPase family members, like Rac1 and Cdc42, which are known to regulate the actin cytoskeleton of synapses.<ref name="IM">PMID: 20117114</ref> PIX has an N-terminal Src homology 3 (SH3) domain which associates with PAK, a coiled-coil (CC) domain, which is critical for multimerization, and a C-terminal PDZ binding domain which interacts with the PDZ domain of Shank.<ref name="IM"/> The interaction of Shank with betaPIX promotes the synaptic localization of betaPIX and betaPIX associated p21 Associated Kinase (PAK). Since PAK is known to regulate the actin cytoskeleton and that dendritic spines are actin-rich structures, it is believed that Shank recruits betaPIX and associated proteins to spines and regulates postsynaptic structure.<ref name="Park"/>
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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;βPIX belongs to a group of guanine nucleotide exchange factors used by Rho GTPase family members, like Rac1 and Cdc42, which are known to regulate the actin cytoskeleton of synapses.<ref name="IM">PMID: 20117114</ref> PIX has an N-terminal Src homology 3 (SH3) domain which associates with PAK, a coiled-coil (CC) domain, which is critical for multimerization, and a C-terminal PDZ binding domain which interacts with the PDZ domain of Shank.<ref name="IM"/> The interaction of Shank with βPIX promotes the synaptic localization of βPIX and βPIX associated p21 Associated Kinase (PAK). Since PAK is known to regulate the actin cytoskeleton and that dendritic spines are actin-rich structures, it is believed that Shank recruits βPIX and associated proteins to spines and regulates postsynaptic structure.<ref name="Park"/>
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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The **canonical PDZ domain** contains 90 amino acids and folds into a compact **globular structure** consisting of a six-stranded beta-sandwich flanked by two alpha helices.<ref name="IM"/> BetaPIX forms a **parallel trimer** via **helical interactions** within its CC domain, and with a **PDZ binding domain** at the C-terminus. Interestingly, only 1 Shank molecule is bound to the CC domain trimer of betaPIX in an **asymettric assembly**. (SHOW ZOOMED OUT IN SPACE FILL WITH LONG PART DIRECTLY VERTICAL) The **8-residue PDZ binding domain** (BALL AND STICK AND SPHERE COMBO BURIED MODE) of BetaPIX forms a number of **hydrogen bonding and hydrophobic interactions** (FIGURE 2A) with the Shank PDZ domain. Shank3-Arg 679 forms the **most critical interaction** with BetaPIX, tightly binding Glutamate -3. Abolishing this interaction through mutagenesis completely eliminates the assembly. Upon binding of betaPIX, the PDZ domain undergoes a significant **conformational change** (OVERVIEW MORPH). Lys 682 undergoes a nearly **11 Angstrom displacement**, ultimately forming a **beta-sheet interaction**, with betaPIX residues -4--6, incorporating Shank residues 680 and 681.<ref name="IM"/>
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&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The **canonical PDZ domain** contains 90 amino acids and folds into a compact **globular structure** consisting of a six-stranded β-sandwich flanked by two alpha helices.<ref name="IM"/> βPIX forms a **parallel trimer** via **helical interactions** within its CC domain, and with a **PDZ binding domain** at the C-terminus. Interestingly, only 1 Shank molecule is bound to the CC domain trimer of βPIX in an **asymettric assembly**. (SHOW ZOOMED OUT IN SPACE FILL WITH LONG PART DIRECTLY VERTICAL) The **8-residue PDZ binding domain** (BALL AND STICK AND SPHERE COMBO BURIED MODE) of βPIX forms a number of **hydrogen bonding and hydrophobic interactions** (FIGURE 2A) with the Shank PDZ domain. Shank3-Arg 679 forms the **most critical interaction** with βPIX, tightly binding Glutamate -3. Abolishing this interaction through mutagenesis completely eliminates the assembly. Upon binding of βPIX, the PDZ domain undergoes a significant **conformational change** (OVERVIEW MORPH). Lys 682 undergoes a nearly **11 Angstrom displacement**, ultimately forming a **beta-sheet interaction**, with βPIX residues -4--6, incorporating Shank residues 680 and 681.<ref name="IM"/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Shank proteins are wedged between scaffolding proteins that are bound to either neurotransmitter receptors or the actin cytoskeleton, making them well positioned to nucleate the underlying structure of the PSD.<ref name="Baron"/> The SAM domain of **Shank3 can oligomerize** to form large sheets composed of helical fibers stacked side by side. The proposed sheet structure with radially projecting protein interaction domains, appears to be an ideal architecture for a protein that must contact both membrane and cytoplasmic components at a cell surface. A number of hydrogen bonding and hydrophobic interactions stabilize the **intra-polymer** interface and the inter-polymer interfaces, labeled **contact 1** and **contact 2**.<ref name="Baron"/> Models of this sort validate the importance of Shank3 as master scaffolding proteins and illustrate how slight mutations can disrupt an entire PSD and synaptic function.
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Shank proteins are wedged between scaffolding proteins that are bound to either neurotransmitter receptors or the actin cytoskeleton, making them well positioned to nucleate the underlying structure of the PSD.<ref name="Baron"/> The SAM domain of **Shank3 can oligomerize** to form large sheets composed of helical fibers stacked side by side. The proposed sheet structure with radially projecting protein interaction domains, appears to be an ideal architecture for a protein that must contact both membrane and cytoplasmic components at a cell surface. A number of hydrogen bonding and hydrophobic interactions stabilize the **intra-polymer** interface and the inter-polymer interfaces, labeled **contact 1** and **contact 2**.<ref name="Baron"/> Models of this sort validate the importance of Shank3 as master scaffolding proteins and illustrate how slight mutations can disrupt an entire PSD and synaptic function.

Revision as of 05:17, 2 March 2011

Structure of Shank Family Proteins, 3l4f

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Additional Structures of Shank Family Proteins

References

  1. ↑ 1.0 1.1 1.2 Park E, Na M, Choi J, Kim S, Lee JR, Yoon J, Park D, Sheng M, Kim E. The Shank family of postsynaptic density proteins interacts with and promotes synaptic accumulation of the beta PIX guanine nucleotide exchange factor for Rac1 and Cdc42. J Biol Chem. 2003 May 23;278(21):19220-9. Epub 2003 Mar 7. PMID:12626503 doi:10.1074/jbc.M301052200
  2. ↑ 2.0 2.1 2.2 Baron MK, Boeckers TM, Vaida B, Faham S, Gingery M, Sawaya MR, Salyer D, Gundelfinger ED, Bowie JU. An architectural framework that may lie at the core of the postsynaptic density. Science. 2006 Jan 27;311(5760):531-5. PMID:16439662 doi:311/5760/531
  3. ↑ 3.0 3.1 3.2 Durand CM, Betancur C, Boeckers TM, Bockmann J, Chaste P, Fauchereau F, Nygren G, Rastam M, Gillberg IC, Anckarsater H, Sponheim E, Goubran-Botros H, Delorme R, Chabane N, Mouren-Simeoni MC, de Mas P, Bieth E, Roge B, Heron D, Burglen L, Gillberg C, Leboyer M, Bourgeron T. Mutations in the gene encoding the synaptic scaffolding protein SHANK3 are associated with autism spectrum disorders. Nat Genet. 2007 Jan;39(1):25-7. Epub 2006 Dec 17. PMID:17173049 doi:ng1933
  4. ↑ 4.0 4.1 4.2 4.3 Bozdagi O, Sakurai T, Papapetrou D, Wang X, Dickstein DL, Takahashi N, Kajiwara Y, Yang M, Katz AM, Scattoni ML, Harris MJ, Saxena R, Silverman JL, Crawley JN, Zhou Q, Hof PR, Buxbaum JD. Haploinsufficiency of the autism-associated Shank3 gene leads to deficits in synaptic function, social interaction, and social communication. Mol Autism. 2010 Dec 17;1(1):15. PMID:21167025 doi:10.1186/2040-2392-1-15
  5. ↑ Garber K. Neuroscience. Autism's cause may reside in abnormalities at the synapse. Science. 2007 Jul 13;317(5835):190-1. PMID:17626859 doi:10.1126/science.317.5835.190
  6. ↑ Abu-Elneel K, Liu T, Gazzaniga FS, Nishimura Y, Wall DP, Geschwind DH, Lao K, Kosik KS. Heterogeneous dysregulation of microRNAs across the autism spectrum. Neurogenetics. 2008 Jul;9(3):153-61. Epub 2008 Jun 19. PMID:18563458 doi:10.1007/s10048-008-0133-5
  7. ↑ 7.0 7.1 7.2 7.3 Im YJ, Kang GB, Lee JH, Park KR, Song HE, Kim E, Song WK, Park D, Eom SH. Structural basis for asymmetric association of the betaPIX coiled coil and shank PDZ. J Mol Biol. 2010 Mar 26;397(2):457-66. Epub 2010 Jan 29. PMID:20117114 doi:10.1016/j.jmb.2010.01.048

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