Limits...
The Evolutionarily Conserved LIM Homeodomain Protein LIM-4/LHX6 Specifies the Terminal Identity of a Cholinergic and Peptidergic C. elegans Sensory/Inter/Motor Neuron-Type.

Kim J, Yeon J, Choi SK, Huh YH, Fang Z, Park SJ, Kim MO, Ryoo ZY, Kang K, Kweon HS, Jeon WB, Li C, Kim K - PLoS Genet. (2015)

Bottom Line: Two human LIM-4 orthologs, LHX6 and LHX8, functionally substitute for LIM-4 in C. elegans.Furthermore, C. elegans LIM-4 or human LHX6 can induce cholinergic and peptidergic characteristics in the human neuronal cell lines.Our results indicate that the evolutionarily conserved LIM-4/LHX6 homeodomain proteins function in generation of precise neuronal subtypes.

View Article: PubMed Central - PubMed

Affiliation: Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea.

ABSTRACT
The expression of specific transcription factors determines the differentiated features of postmitotic neurons. However, the mechanism by which specific molecules determine neuronal cell fate and the extent to which the functions of transcription factors are conserved in evolution are not fully understood. In C. elegans, the cholinergic and peptidergic SMB sensory/inter/motor neurons innervate muscle quadrants in the head and control the amplitude of sinusoidal movement. Here we show that the LIM homeobox protein LIM-4 determines neuronal characteristics of the SMB neurons. In lim-4 mutant animals, expression of terminal differentiation genes, such as the cholinergic gene battery and the flp-12 neuropeptide gene, is completely abolished and thus the function of the SMB neurons is compromised. LIM-4 activity promotes SMB identity by directly regulating the expression of the SMB marker genes via a distinct cis-regulatory motif. Two human LIM-4 orthologs, LHX6 and LHX8, functionally substitute for LIM-4 in C. elegans. Furthermore, C. elegans LIM-4 or human LHX6 can induce cholinergic and peptidergic characteristics in the human neuronal cell lines. Our results indicate that the evolutionarily conserved LIM-4/LHX6 homeodomain proteins function in generation of precise neuronal subtypes.

No MeSH data available.


Related in: MedlinePlus

lim-4 mutant animals moved in a coiled or loopy fashion due to the functional defects of the SMB neurons.(A) Wild-type animals show a characteristic sinusoidal waveform whose tracks can also be observed in the bacterial lawn. lim-4(ky403, lsk5, lsk3) mutant animals showed an exaggerated waveform characterized by an increased wave width. Scale bar: 0.5 mm. (B) To quantitate locomotion, the waveforms of different animals were analyzed and compared to that of wild-type animals by viewing tracks made in a bacterial lawn under a microscope. Wave width and wavelength were measured and averaged as the distance from the peak to the trough of the sine wave and distance between one peak and the next corresponding peak, respectively. (C-D) Average of wave width and wavelength of the lim-4 mutant animals (C) or SMB/SAA-ablated animals (D). n≥30 for each. Error bars are the SEM. *, ** and *** indicate significantly different from wild-type at p<0.05, 0.01, and 0.001, respectively (one-way ANOVA test followed by the Tukey post-hoc test). The number of animals tested is indicated on the bars. Note that the size was measured by using the software (C) or a scale built into an eyepiece (D).
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pgen.1005480.g003: lim-4 mutant animals moved in a coiled or loopy fashion due to the functional defects of the SMB neurons.(A) Wild-type animals show a characteristic sinusoidal waveform whose tracks can also be observed in the bacterial lawn. lim-4(ky403, lsk5, lsk3) mutant animals showed an exaggerated waveform characterized by an increased wave width. Scale bar: 0.5 mm. (B) To quantitate locomotion, the waveforms of different animals were analyzed and compared to that of wild-type animals by viewing tracks made in a bacterial lawn under a microscope. Wave width and wavelength were measured and averaged as the distance from the peak to the trough of the sine wave and distance between one peak and the next corresponding peak, respectively. (C-D) Average of wave width and wavelength of the lim-4 mutant animals (C) or SMB/SAA-ablated animals (D). n≥30 for each. Error bars are the SEM. *, ** and *** indicate significantly different from wild-type at p<0.05, 0.01, and 0.001, respectively (one-way ANOVA test followed by the Tukey post-hoc test). The number of animals tested is indicated on the bars. Note that the size was measured by using the software (C) or a scale built into an eyepiece (D).

Mentions: Wild-type animals move in sinusoidal waves of a consistent wave width and wavelength (Fig 3A) [25]. lim-4 mutants move in a coiled or loopy fashion (Fig 3A) [14]. To quantitate the loopy uncoordinated movement, the waveforms of these animals were measured by viewing tracks made in a bacterial lawn and compared to that of wild-type animals (Fig 3B). lim-4 mutants had significantly accentuated waveforms (Fig 3C). While the average wavelength for lim-4 mutants (ky403 or lsk5) is similar or mildly decreased compared to that of wild-type animals, the average wave width for ky403 or lsk5 mutants (ky403: 359.46±13.51 μm, n = 30; lsk5: 374.27±16.47 μm, n = 30) is about 70% higher than that of wild-type animals (N2: 194.54±4.28 μm, n = 30) (Fig 3A and 3C). yn19 and lsk3 missense mutants similarly exhibited significantly larger wave width (yn19: 312.31±7.75 μm, n = 30; lsk3: 365.43±11.97 μm, n = 30) (Fig 3A and 3C), suggesting that yn19 and lsk3 mutations also fully eliminate the contribution of LIM-4 to locomotion.


The Evolutionarily Conserved LIM Homeodomain Protein LIM-4/LHX6 Specifies the Terminal Identity of a Cholinergic and Peptidergic C. elegans Sensory/Inter/Motor Neuron-Type.

Kim J, Yeon J, Choi SK, Huh YH, Fang Z, Park SJ, Kim MO, Ryoo ZY, Kang K, Kweon HS, Jeon WB, Li C, Kim K - PLoS Genet. (2015)

lim-4 mutant animals moved in a coiled or loopy fashion due to the functional defects of the SMB neurons.(A) Wild-type animals show a characteristic sinusoidal waveform whose tracks can also be observed in the bacterial lawn. lim-4(ky403, lsk5, lsk3) mutant animals showed an exaggerated waveform characterized by an increased wave width. Scale bar: 0.5 mm. (B) To quantitate locomotion, the waveforms of different animals were analyzed and compared to that of wild-type animals by viewing tracks made in a bacterial lawn under a microscope. Wave width and wavelength were measured and averaged as the distance from the peak to the trough of the sine wave and distance between one peak and the next corresponding peak, respectively. (C-D) Average of wave width and wavelength of the lim-4 mutant animals (C) or SMB/SAA-ablated animals (D). n≥30 for each. Error bars are the SEM. *, ** and *** indicate significantly different from wild-type at p<0.05, 0.01, and 0.001, respectively (one-way ANOVA test followed by the Tukey post-hoc test). The number of animals tested is indicated on the bars. Note that the size was measured by using the software (C) or a scale built into an eyepiece (D).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4549117&req=5

pgen.1005480.g003: lim-4 mutant animals moved in a coiled or loopy fashion due to the functional defects of the SMB neurons.(A) Wild-type animals show a characteristic sinusoidal waveform whose tracks can also be observed in the bacterial lawn. lim-4(ky403, lsk5, lsk3) mutant animals showed an exaggerated waveform characterized by an increased wave width. Scale bar: 0.5 mm. (B) To quantitate locomotion, the waveforms of different animals were analyzed and compared to that of wild-type animals by viewing tracks made in a bacterial lawn under a microscope. Wave width and wavelength were measured and averaged as the distance from the peak to the trough of the sine wave and distance between one peak and the next corresponding peak, respectively. (C-D) Average of wave width and wavelength of the lim-4 mutant animals (C) or SMB/SAA-ablated animals (D). n≥30 for each. Error bars are the SEM. *, ** and *** indicate significantly different from wild-type at p<0.05, 0.01, and 0.001, respectively (one-way ANOVA test followed by the Tukey post-hoc test). The number of animals tested is indicated on the bars. Note that the size was measured by using the software (C) or a scale built into an eyepiece (D).
Mentions: Wild-type animals move in sinusoidal waves of a consistent wave width and wavelength (Fig 3A) [25]. lim-4 mutants move in a coiled or loopy fashion (Fig 3A) [14]. To quantitate the loopy uncoordinated movement, the waveforms of these animals were measured by viewing tracks made in a bacterial lawn and compared to that of wild-type animals (Fig 3B). lim-4 mutants had significantly accentuated waveforms (Fig 3C). While the average wavelength for lim-4 mutants (ky403 or lsk5) is similar or mildly decreased compared to that of wild-type animals, the average wave width for ky403 or lsk5 mutants (ky403: 359.46±13.51 μm, n = 30; lsk5: 374.27±16.47 μm, n = 30) is about 70% higher than that of wild-type animals (N2: 194.54±4.28 μm, n = 30) (Fig 3A and 3C). yn19 and lsk3 missense mutants similarly exhibited significantly larger wave width (yn19: 312.31±7.75 μm, n = 30; lsk3: 365.43±11.97 μm, n = 30) (Fig 3A and 3C), suggesting that yn19 and lsk3 mutations also fully eliminate the contribution of LIM-4 to locomotion.

Bottom Line: Two human LIM-4 orthologs, LHX6 and LHX8, functionally substitute for LIM-4 in C. elegans.Furthermore, C. elegans LIM-4 or human LHX6 can induce cholinergic and peptidergic characteristics in the human neuronal cell lines.Our results indicate that the evolutionarily conserved LIM-4/LHX6 homeodomain proteins function in generation of precise neuronal subtypes.

View Article: PubMed Central - PubMed

Affiliation: Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea.

ABSTRACT
The expression of specific transcription factors determines the differentiated features of postmitotic neurons. However, the mechanism by which specific molecules determine neuronal cell fate and the extent to which the functions of transcription factors are conserved in evolution are not fully understood. In C. elegans, the cholinergic and peptidergic SMB sensory/inter/motor neurons innervate muscle quadrants in the head and control the amplitude of sinusoidal movement. Here we show that the LIM homeobox protein LIM-4 determines neuronal characteristics of the SMB neurons. In lim-4 mutant animals, expression of terminal differentiation genes, such as the cholinergic gene battery and the flp-12 neuropeptide gene, is completely abolished and thus the function of the SMB neurons is compromised. LIM-4 activity promotes SMB identity by directly regulating the expression of the SMB marker genes via a distinct cis-regulatory motif. Two human LIM-4 orthologs, LHX6 and LHX8, functionally substitute for LIM-4 in C. elegans. Furthermore, C. elegans LIM-4 or human LHX6 can induce cholinergic and peptidergic characteristics in the human neuronal cell lines. Our results indicate that the evolutionarily conserved LIM-4/LHX6 homeodomain proteins function in generation of precise neuronal subtypes.

No MeSH data available.


Related in: MedlinePlus