TTC8

Cilia effects upon perturbation of TTC8

Cilia number / % ciliated:

Decreased cilia number

Loss-of-function effect:

Shorter cilia

Overexpression effect:

Unknown

Ciliogenesis screen results (6 screens)

• Kim2016: Not Reported
• Wheway et al. 2015 (siRNA) [siRNA]: Hyper-ciliogenesis (z=2.28) PMID:26167766
• Breslow et al. 2018 (CRISPR) [CRISPR]: Positive Regulator (Hh signaling, casTLE effect=-2.37) PMID:29459680
• Roosing et al. 2015 (siRNA) [siRNA]: No effect PMID:26595381
• Pusapati et al. 2018 (CRISPR) [CRISPR]: Positive Regulator (Hh signaling, neg_rank=81, lfc=-1.86) PMID:30270045
• Elliott et al. 2025 (CRISPRa) [CRISPRa]: Disassembly Trigger (casTLE Effect=-3.89) PMID:41160700

Phenotypes

Human ciliopathy phenotype:

Bardet-Biedl syndrome; retinitis pigmentosa; Bardet-Biedl syndrome 1

Ciliopathy associations

• Bardet-Biedl Syndrome
• Retinal Dystrophy/Degeneration

Subcellular localization

basal body, centrosome, flagella

Functional category

• Ciliary assembly/disassembly
• Trafficking (BBSome, small GTPases, vesicular transport, ATPases)
• Actin & cytoskeleton regulation
• T cell biology
• Neurogenesis & migration
• Signaling (Hedgehog, GPCRs, ion channels)
• Ciliary membrane
• Transition zone
• Axon guidance & growth
• Transcription regulation

Function

Also known as BBS8. Component of the BBSome complex, interacts with PCM1. Mutations leads to Bardet-Biedl syndrome with randomization of left-right body axis symmetry (14520415). Role in intraciliary/flagellar transport, coordi ting the velocity of the kinesin molecular motors during anterograde transport. Interacts with Vangl2 to establish and maintain of vertebrate left-right asymmetry. It may also be responsible for maintaining normal cilium length in the KV but not cilia number (20643117). Required for the development, mainte nce and survival of photoreceptors and outer segments in both rods and cones (29126234). Knockdown reduces ciliary length and increases levels of HDAC6 (30446775).

Model organism evidence