Rabbit Anti-Human SHH monoclonal antibody, clone TD16-39

Attachment of palmitate to the N terminus of Sonic hedgehog (Shh) is essential for Shh signaling. Shh palmitoylation is catalyzed on the luminal side of the endoplasmic reticulum (ER) by Hedgehog acyltransferase (Hhat), an ER-resident enzyme. Palmitoyl-coenzyme A (CoA), the palmitate donor, is produced in the cytosol and is not permeable across membrane bilayers. It is not known how palmitoyl-CoA crosses the ER membrane to access the active site of Hhat. Here, we use fluorescent and radiolabeled palmitoyl-CoA probes to demonstrate that Hhat promotes the uptake of palmitoyl-CoA across the ER membrane in microsomes and semi-intact cells. Reconstitution of purified Hhat into liposomes provided further evidence that palmitoyl-CoA uptake activity is an intrinsic property of Hhat. Palmitoyl-CoA uptake was regulated by and could be uncoupled from Hhat enzymatic activity, implying that Hhat serves a dual function as a palmitoyl acyl-transferase and a conduit to supply palmitoyl-CoA to the luminal side of the ER.

ZC4H2 encodes a C4H2 type zinc-finger nuclear factor, the mutation of which has been associated with disorders with various clinical phenotypes in human, including developmental delay, intellectual disability and dystonia. ZC4H2 has been suggested to regulate spinal cord patterning in zebrafish as a co-factor for RNF220, an ubiquitin E3 ligase involved in Gli signaling. Here we showed that ZC4H2 and RNF220 knockout animals phenocopy each other in spinal patterning in both mouse and zebrafish, with mispatterned progenitor and neuronal domains in the ventral spinal cord. We showed evidence that ZC4H2 is required for the stability of RNF220 and also proper Gli ubiquitination and signaling in vivo. Our data providesnew insights into the possible etiology of the neurodevelopmental impairments observed in ZC4H2-associated syndromes.