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Novel function of PIWIL1 in neuronal polarization and migration via regulation of microtubule-associated proteins.

Zhao PP, Yao MJ, Chang SY, Gou LT, Liu MF, Qiu ZL, Yuan XB - Mol Brain (2015)

Bottom Line: Furthermore, we found that PIWIL1 unexpectedly regulates the expression of microtubule-associated proteins in cortical neurons.PIWIL1 regulates neuronal polarization and radial migration partly via modulating the expression of microtubule-associated proteins (MAPs).Our finding of PIWIL1's function in neuronal development implies conserved functions of molecules participating in morphogenesis of brain and germline tissue and provides a mechanism as to how mutations of PIWI may be associated with autism.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China.

ABSTRACT

Background: Young neurons in the developing brain establish a polarized morphology for proper migration. The PIWI family of piRNA processing proteins are considered to be restrictively expressed in germline tissues and several types of cancer cells. They play important roles in spermatogenesis, stem cell maintenance, piRNA biogenesis, and transposon silencing. Interestingly a recent study showed that de novo mutations of PIWI family members are strongly associated with autism.

Results: Here, we report that PIWI-like 1 (PIWIL1), a PIWI family member known to be essential for the transition of round spermatid into elongated spermatid, plays a role in the polarization and radial migration of newborn neurons in the developing cerebral cortex. Knocking down PIWIL1 in newborn cortical neurons by in utero electroporation of specific siRNAs resulted in retardation of the transition of neurons from the multipolar stage to the bipolar stage followed by a defect in their radial migration to the proper destination. Domain analysis showed that both the RNA binding PAZ domain and the RNA processing PIWI domain in PIWIL1 were indispensable for its function in neuronal migration. Furthermore, we found that PIWIL1 unexpectedly regulates the expression of microtubule-associated proteins in cortical neurons.

Conclusions: PIWIL1 regulates neuronal polarization and radial migration partly via modulating the expression of microtubule-associated proteins (MAPs). Our finding of PIWIL1's function in neuronal development implies conserved functions of molecules participating in morphogenesis of brain and germline tissue and provides a mechanism as to how mutations of PIWI may be associated with autism.

No MeSH data available.


Related in: MedlinePlus

PIWIL1 regulates cortical radial migration. a-f Effect of knockdown of PIWIL1 in rat cortical neurons by IUE with plasmids coding for PIWIL1 siRNA (RNAi 1). Coronal brain sections at different stages were stained with anti-GFP (green) and DAPI (red). g-l Distribution of labeled cells in brains electroporated with RNAi 1 (g-i) and RNAi 4 (j-l) or control constructs (Scramble). m Different forms of truncated human PIWIL1 (HIWI) or mutated mouse PIWIL1. n-s, u Only constructs containing both PAZ and PIWI domains rescued the migration. The Scramble control data were from the experiment in Additional file 2: Figure S2E. CAG, pCAG-IRES-GFP vector as control. t, u Co-electroporation of D633A-Res with RNAi 2 rescued the migration defect. Scale bar, 250 μm. Error bar, SEM. *P < 0.05, **P < 0.01, ***P < 0.001 (Student’s t-test)
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Fig1: PIWIL1 regulates cortical radial migration. a-f Effect of knockdown of PIWIL1 in rat cortical neurons by IUE with plasmids coding for PIWIL1 siRNA (RNAi 1). Coronal brain sections at different stages were stained with anti-GFP (green) and DAPI (red). g-l Distribution of labeled cells in brains electroporated with RNAi 1 (g-i) and RNAi 4 (j-l) or control constructs (Scramble). m Different forms of truncated human PIWIL1 (HIWI) or mutated mouse PIWIL1. n-s, u Only constructs containing both PAZ and PIWI domains rescued the migration. The Scramble control data were from the experiment in Additional file 2: Figure S2E. CAG, pCAG-IRES-GFP vector as control. t, u Co-electroporation of D633A-Res with RNAi 2 rescued the migration defect. Scale bar, 250 μm. Error bar, SEM. *P < 0.05, **P < 0.01, ***P < 0.001 (Student’s t-test)

Mentions: To test the potential function of PIWIL1 in the development of cortical neurons, we first used IUE of plasmids coding for short interference RNAs (siRNAs) targeting PIWIL1 (knockdown efficiency was validated (Additional file 2: Figure S2A and B)) together with plasmids coding for EYFP into cortical progenitor cells in the VZ of rat cortex at E16. At postnatal day 1 (P1), most cells electroporated with the PIWIL1 siRNA (RNAi 1 for rat) failed to migrate into the CP. This migration retardation persisted to later stages of P3 and P5, with aberrantly accumulated cells located in the IZ or deep layers of the CP (upCP, Upper CP; loCP, Lower CP, Fig. 1a-i). Electroporation with another siRNA for rat (RNAi 4, Fig. 1j-l) or effective siRNA for mouse (RNAi 2) (Additional file 2: Figure S2C-E) resulted in a similar migration defect in rat and mouse, respectively. Although overexpression of human PIWIL1 (HIWI) alone did not promote the neuronal migration in mouse cortex (Additional file 2: Figure S2F-H), co-transfection of RNAi 2 along with HIWI, which is highly homologous to mouse PIWIL1 in the protein sequence but could not be targeted by RNAi 2, blocked the knockdown phenotype in mouse cortex (RNAi 2 + CAG v.s. RNAi 2 + HIWI) (Fig. 1n, o, u). Together, these data suggest a specific role of PIWIL1 in the regulation of the radial migration of cortical neurons.Fig. 1


Novel function of PIWIL1 in neuronal polarization and migration via regulation of microtubule-associated proteins.

Zhao PP, Yao MJ, Chang SY, Gou LT, Liu MF, Qiu ZL, Yuan XB - Mol Brain (2015)

PIWIL1 regulates cortical radial migration. a-f Effect of knockdown of PIWIL1 in rat cortical neurons by IUE with plasmids coding for PIWIL1 siRNA (RNAi 1). Coronal brain sections at different stages were stained with anti-GFP (green) and DAPI (red). g-l Distribution of labeled cells in brains electroporated with RNAi 1 (g-i) and RNAi 4 (j-l) or control constructs (Scramble). m Different forms of truncated human PIWIL1 (HIWI) or mutated mouse PIWIL1. n-s, u Only constructs containing both PAZ and PIWI domains rescued the migration. The Scramble control data were from the experiment in Additional file 2: Figure S2E. CAG, pCAG-IRES-GFP vector as control. t, u Co-electroporation of D633A-Res with RNAi 2 rescued the migration defect. Scale bar, 250 μm. Error bar, SEM. *P < 0.05, **P < 0.01, ***P < 0.001 (Student’s t-test)
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Related In: Results  -  Collection

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Fig1: PIWIL1 regulates cortical radial migration. a-f Effect of knockdown of PIWIL1 in rat cortical neurons by IUE with plasmids coding for PIWIL1 siRNA (RNAi 1). Coronal brain sections at different stages were stained with anti-GFP (green) and DAPI (red). g-l Distribution of labeled cells in brains electroporated with RNAi 1 (g-i) and RNAi 4 (j-l) or control constructs (Scramble). m Different forms of truncated human PIWIL1 (HIWI) or mutated mouse PIWIL1. n-s, u Only constructs containing both PAZ and PIWI domains rescued the migration. The Scramble control data were from the experiment in Additional file 2: Figure S2E. CAG, pCAG-IRES-GFP vector as control. t, u Co-electroporation of D633A-Res with RNAi 2 rescued the migration defect. Scale bar, 250 μm. Error bar, SEM. *P < 0.05, **P < 0.01, ***P < 0.001 (Student’s t-test)
Mentions: To test the potential function of PIWIL1 in the development of cortical neurons, we first used IUE of plasmids coding for short interference RNAs (siRNAs) targeting PIWIL1 (knockdown efficiency was validated (Additional file 2: Figure S2A and B)) together with plasmids coding for EYFP into cortical progenitor cells in the VZ of rat cortex at E16. At postnatal day 1 (P1), most cells electroporated with the PIWIL1 siRNA (RNAi 1 for rat) failed to migrate into the CP. This migration retardation persisted to later stages of P3 and P5, with aberrantly accumulated cells located in the IZ or deep layers of the CP (upCP, Upper CP; loCP, Lower CP, Fig. 1a-i). Electroporation with another siRNA for rat (RNAi 4, Fig. 1j-l) or effective siRNA for mouse (RNAi 2) (Additional file 2: Figure S2C-E) resulted in a similar migration defect in rat and mouse, respectively. Although overexpression of human PIWIL1 (HIWI) alone did not promote the neuronal migration in mouse cortex (Additional file 2: Figure S2F-H), co-transfection of RNAi 2 along with HIWI, which is highly homologous to mouse PIWIL1 in the protein sequence but could not be targeted by RNAi 2, blocked the knockdown phenotype in mouse cortex (RNAi 2 + CAG v.s. RNAi 2 + HIWI) (Fig. 1n, o, u). Together, these data suggest a specific role of PIWIL1 in the regulation of the radial migration of cortical neurons.Fig. 1

Bottom Line: Furthermore, we found that PIWIL1 unexpectedly regulates the expression of microtubule-associated proteins in cortical neurons.PIWIL1 regulates neuronal polarization and radial migration partly via modulating the expression of microtubule-associated proteins (MAPs).Our finding of PIWIL1's function in neuronal development implies conserved functions of molecules participating in morphogenesis of brain and germline tissue and provides a mechanism as to how mutations of PIWI may be associated with autism.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neuroscience and State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China.

ABSTRACT

Background: Young neurons in the developing brain establish a polarized morphology for proper migration. The PIWI family of piRNA processing proteins are considered to be restrictively expressed in germline tissues and several types of cancer cells. They play important roles in spermatogenesis, stem cell maintenance, piRNA biogenesis, and transposon silencing. Interestingly a recent study showed that de novo mutations of PIWI family members are strongly associated with autism.

Results: Here, we report that PIWI-like 1 (PIWIL1), a PIWI family member known to be essential for the transition of round spermatid into elongated spermatid, plays a role in the polarization and radial migration of newborn neurons in the developing cerebral cortex. Knocking down PIWIL1 in newborn cortical neurons by in utero electroporation of specific siRNAs resulted in retardation of the transition of neurons from the multipolar stage to the bipolar stage followed by a defect in their radial migration to the proper destination. Domain analysis showed that both the RNA binding PAZ domain and the RNA processing PIWI domain in PIWIL1 were indispensable for its function in neuronal migration. Furthermore, we found that PIWIL1 unexpectedly regulates the expression of microtubule-associated proteins in cortical neurons.

Conclusions: PIWIL1 regulates neuronal polarization and radial migration partly via modulating the expression of microtubule-associated proteins (MAPs). Our finding of PIWIL1's function in neuronal development implies conserved functions of molecules participating in morphogenesis of brain and germline tissue and provides a mechanism as to how mutations of PIWI may be associated with autism.

No MeSH data available.


Related in: MedlinePlus