A meckelin-filamin A interaction mediates ciliogenesis

Area of Science:

• Cell Biology
• Developmental Biology
• Genetics

Background:

• Meckel-Gruber syndrome (MKS) is an autosomal-recessive ciliopathy caused by mutations in MKS3, which encodes meckelin.
• Meckelin localizes to primary cilia and basal bodies, essential cellular structures.
• Mutations in FLNA, encoding filamin A, are linked to periventricular heterotopias, a brain developmental disorder.

Purpose of the Study:

• To investigate the interaction between meckelin and filamin A.
• To understand the molecular basis of a patient presenting with both MKS and cerebellar heterotopia.
• To elucidate the roles of meckelin and filamin A in ciliogenesis and neuronal development.

Main Methods:

• Investigated the interaction between meckelin's cytoplasmic domain and filamin A using biochemical assays.
• Analyzed a patient with a novel in-frame deletion mutation in MKS3.
• Utilized siRNA knockdown of filamin A in patient cells and studied Flna(Dilp2) null mouse embryos.
• Performed morpholino knockdown of flna in zebrafish embryos.

Main Results:

• Identified a direct interaction between the cytoplasmic domain of meckelin and filamin A.
• Characterized a patient with MKS-like ciliopathy and cerebellar heterotopia due to a mutation abrogating the meckelin-filamin A interaction.
• Demonstrated that loss of filamin A phenocopies meckelin loss, causing basal body positioning and ciliogenesis defects.
• Showed that reduced filamin A exacerbates ciliopathy defects caused by MKS3 knockdown in zebrafish.

Conclusions:

• Meckelin and filamin A form a functional complex critical for ciliogenesis and basal body positioning.
• Disruption of the meckelin-filamin A complex contributes to Meckel-Gruber syndrome and neuronal migration defects.
• The meckelin-filamin A axis is implicated in regulating Wnt signaling pathways.
• Filamin A plays a vital role in normal ciliogenesis and neuronal development.