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| Loss of function (null allele) | Gain of function/RNAi transgenes | Phenotypes |
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| Feiguin et al. [6] | Generation of mutants carrying chromosomal deletions. Two excised lines (TBPH D23 and TBPH D142) show small 1.6 and 0.8 kb deletions, respectively (that partially removed part of TBPH regulatory and coding regions) | Generation of transgenic flies with TBPH and hTDP-43 add back in TBPH knockout backgrounds using the D42-GAL4 or elav-GAL4 drivers. | Homozygous TBPH-KO flies were viable after embryogenesis. Homozygous flies that got rid of the external cuticle presented dramatic locomotive defects with spastic, uncoordinated, movements, incapacity to fly or walk normally and reduced life span. In TBPH-KO larvae, the number of axonal branches and synaptic boutons inside the muscles were reduced in the presynaptic terminals. Loss of TDP-43 function alters the morphological organization of the NMJ. |
| | TBPH RNAi lines were obtained. | RNAi caused similar locomotive defects |
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| Lu et al. [7] | Generation of null allele carrying nonsense mutation with a single nucleotide change (G>A introduced a stop codon at codon 367 in TBPH-43 Q367X) | Generation of hTDP-43WT and hTDP-43 Q331K or hTDP- 43 M337V UAS-hTDP-43 transgenic flies. | Homozygosity for TBPH-43Q367X was semi-lethal, with some mutant adult flies surviving to adulthood. The number of small terminal dendritic branches was increased by overexpression of TBPH-43. Their localization was concentrated near the cell body of ddaE neurons. Ectopic expression of Q331K and M337V mutant proteins promoted dendritic branching to a much lesser extent than wild-type hTDP-43. |
| | Expression of UAS-TBPH-43 RNAi (38377 or 38379, VDRC) driven by tubulin-Gal4 | RNAi resulted in a similar lethal phenotype. |
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| Voigt et al. [8] | | Generation of synthetic mutants (TDP-43SM) and ALS/FTLD-linked TDP-43MS TBPH-43 transgenic UAS/Gal4 fly lines: TDP-43SM variants (WT; ΔNLS; F147L/F149L; CTF, lacking the N-terminal portion including RRM1). ALS/FTLD-linked TDP-43MS variants (A315T;G287S;A382T;N390D). | All TDP-43 variants but TDP-43CTF and TDP-43FFLL caused premature lethality. All TDP-43 variants caused reduction in life span.
Dose dependency of TDP-43-mediated neurotoxicity (TDP-43WT and TDP-43NLS). Although still alive, 20d-old TDP-43_WT expressing flies appeared paralytic, hardly showed coordinated movement, and failed to climb. Loss of motor neurons caused by TDP-43WT > TDP-43A315T and TDP-43DNLS. |
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| Fiesel et al. [9] | Generation of null allele where the entire CDS of the TBPH gene was deleted | | TBPH -/- animals die as second-instar larvae. The ability of hTDP-43 to bind and regulate expression of the HDAC6 mRNA is conserved also by TBPH and dhdac6 in Drosophila. |
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| Hanson et al. [10] | | To test the consequences of the TDP-43/UBQLN interaction in vivo, transgenic Drosophila lines were created with cDNAs encoding either wild-type human TDP-43 or human UBQLN under UAS/GAL4 control. GMR-Gal4 driver was used to express human TDP-43 in the fly eye. D42-Gal4 driver was used to express TDP-43 exclusively in motor neurons. | Overexpression of TDP-43 is toxic in the fly eyes. TDP-43 toxicity is both dose dependent and age dependent. TDP-43 expression in motor neurons reduces life span. UBQLN increases TDP-43 toxicity in both Drosophila and mammalian systems. |
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| Li et al. [11] | | Expression of hTDP-43 in Drosophila eyes with GMR-Gal4 driver beginning at the third instar larva. Overexpressed hTDP-43: WT or mutant T202 (containing the carboxyl-terminal glycine-rich domain but lacking the amino-terminal RNA recognition motif). | Overexpression of TDP-43 is toxic in the fly eyes. Both overexpression and silencing of hTDP-43 in mushroom bodies causes axonal and neuronal loss. Expression of hTDP-43 in motor neurons causes formation of aggregates in cell bodies and axons, as well as axon swelling. hTDP-43-expression causes age-dependent reduction in flies motility. |
| | Expression of hTDP-43 in Mushroom Bodies with OK107-Gal4 driver. | |
| | Expression of hTDP-43 in a small subset of MNs at the adult stage with RN2-Gal4 driver | |
| | TBPH RNAi lines were obtained. | |
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| Ritson et al. [12] | | Generation of transgenic flies expressing human WT or mutant TDP-43 using the UAS/GAL4 system. Used NES-mutant TDP-43 (nuclear) and NLS-mutant TDP-43 (cytoplasmic). TDP-43 (WT or mutant) under control of the driver fkh-GAL4. | In the eye, expression of dVCP-wt caused a modest phenotypic change, whereas matched expression of the R152H and A229E mutants caused severe external rough eye phenotypes with necrotic patches and vacuolar degeneration. Generation of transgenic lines overexpressing TBPH resulted in a degenerative phenotype when targeted to the eye. |
| | Expression of the ALS-causing mutation M337V (leads to toxicity associated with cytoplasmic redistribution of TDP-43). | The ALS-causing mutation M337V expressed in vivo leads to toxicity associated with cytoplasmic redistribution of TDP-43. |
| | Flies transgenic for UAS-dVCP (WT or mutant), UAS- TBPH, and UAS-TDP-43 (WT or mutant) were generated | Coexpression of exogenous TBPH with dVCP R152H enhanced degeneration associated with mutant VCP and confirming the genetic interaction. |
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| | TBPH RNAi lines were obtained. | |
| Estes et al. [13] | | Transgenic lines were generated to express TBPH and hTDP-43 wild-types and A315T mutants. Gal4 drivers used included the GMR-Gal4 and the D42-Gal4. | Overexpression of WT- and A315T-TDP-43 is toxic for the retina of fly eyes. TBPH-wt is 100% lethal when overexpressed at higher levels (by raising the temperature at 29°C). Wild-type and mutant TDP-43 create axonal aggregates in the developing eyes.
Motor neurons expressing TDP-43 variants exhibit morphological defects at the NMJ synapse. Locomotor activity, viability, and survival are impaired regardless of the presence of detectable TDP-43 cytoplasmic aggregates. |
| | TBPH RNAi lines were obtained. | TBPH-RNAi enhances the toxic effect of both wild-type and A315T hTDP-43 expression in motor neurons. |
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| Guo W. et al. [14] | | Expression of hTDP-43 (WT or A315T) with OK371-Gal4 driver in subsets of motor neurons. | Flies often failed to eclose and surviving flies were smaller than control flies. Neurotoxicity and motor neuron deficits with mutant TDP-43. Expression of either wild-type or A315T mutant TDP-43 caused axonal abnormalities. Motor neurons expressing wild-type or mutant TDP-43 showed axonal swelling. Expression of A315T caused frequent fly death before the 3rd-instar stage. Surviving flies showed a marked axonal loss. In the remaining axons we detected severe damage, including axon swelling, axon thinning, and defects in axonal integrity. Expression of A315T (compared to wild-type) TDP-43 caused higher neuronal loss. |
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| Lanson et al. [15] | | The genetic interaction between human FUS/TLS and TDP-43 was tested by using transgenic TDP-43 flies described by Ritson et al. | Ectopic expression of mutant FUS/TLS leads to neurodegeneration in Drosophila. Genetic interaction between human FUS/TLS and TDP-43 tested by using transgenic TDP-43 flies described by Ritson et al. Eye expression of FUS WT or TDP-43 WT alone did not cause significant degeneration. |
| | | Coexpression of both proteins caused moderate eye degeneration. Co-expression of FUS WT with M337V-TDP-43 led to severe eye degeneration. Co-expression of R521H FUS with TDP-43 WT synergistically enhanced the degeneration. |
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| Li et al. [16] | | GMR-Gal4 and elav-Gal4 were used to drive expression of wt (fTDP) and three truncated forms of TDP with N-terminal 104 (ND104), 207 (ND207), and 251 (ND251) amino acids deleted. | ND104, ND207, and ND251 were concentrated and formed aggregates in cytoplasm because of the lack of nuclear localization signal (NLS). The pattern of insoluble ND251 highlighted a shorter fragment and high molecular weight, similar to what is observed in TDP-ALS/FTLD-U inclusions. |
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| Lin et al. [17] | | Different GAL4 drivers were used to induce tissue-specific TBPH knockdown (Elav4;OK107; D42; MHC). | Pan-neuronal TBPH knockdown caused reduction in the moving abilities of larvae. |
| | Motor neurons TBPH overexpression reduced fly locomotor activities, along with a decrease of the number of boutons and axon branches at NMJ. TBPH overexpression in the mushroom bodies caused smaller axonal lobes and learning deficiency. Mushroom body-specific TBPH-knockdown did not affect the structure of the mushroom bodies, but caused modest reduction in the learning ability. TBPH-overexpression caused the formation of cytosolic TBPH aggregates. |
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| Miguel et al. [18] | | Different GAL4 drivers were used to induce tissue-specific TBPH-knockdown (Elav4; Repo; 24B; GMR). | Expression of TDP-43 wild-type is toxic for Drosophila eyes, muscles, and glia. |
| | Both nuclear and cytoplasmic TDP-43 accumulations are toxic for neurons (regardless of the formation of inclusions). Expression of human TDP-43 in adult flies neurons results in abnormally phosphorylation of the disease-specific Ser409/Ser410 residues and presence of high molecular weight forms in flies. |
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| Godena et al. [19] | | The previously generated TBPH-ko fly lines (Feiguin, 2009) were used to characterize the pathological consequences of TBPH-43 altered function in the Drosophila neuromuscular junctions during larval development. | TDP-43 is necessary for presynaptic microtubule organization: TBPH was found to modulate the expression of futsch, a neuron-specific microtubule binding protein ortholog of the human MAP1B important for maintaining the microtubule integrity during neuromuscular junctions expansion. |
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