Menkes Disease

The protein encoded by the Menkes disease gene (MNK) is localised to the Golgi apparatus and cycles between the trans-Golgi network and the plasma membrane in cultured cells on addition and removal of copper to the growth medium. This suggests that MNK protein contains active signals that are involved in the retention of the protein to the trans-Golgi network and retrieval of the protein from the plasma membrane. Previous studies have identified a signal involved in Golgi retention within transmembrane domain 3 of MNK. To identify a motif sufficient for retrieval of MNK from the plasma membrane, we analysed the cytoplasmic domain, downstream of transmembrane domain 7 and 8. Chimeric constructs containing this cytoplasmic domain fused to the reporter molecule CD8 localised the retrieval signal(s) to 62 amino acids at the C terminus. Further studies were performed on putative internalisation motifs, using site-directed mutagenesis, protein expression, chemical treatment and immunofluorescence. We observed that a di-leucine motif (L1487L1488) was essential for rapid internalisation of chimeric CD8 proteins and the full-length Menkes cDNA from the plasma membrane. We suggest that this motif mediates the retrieval of MNK from the plasma membrane into the endocytic pathway, via the recycling endosomes, but is not sufficient on its own to return the protein to the Golgi apparatus. These studies provide a basis with which to identify other motifs important in the sorting and delivery of MNK from the plasma membrane to the Golgi apparatus.

Download Full-text

CONGENITAL CUTIS LAXA: A RARE GENODERMATOSIS

10.36106/gjra/4507594 ◽

2021 ◽

pp. 20-21

Author(s):

Vinaya Ajaykumar Singh ◽

Mazhar Khan ◽

Poonam Wade ◽

Navina Desai ◽

Sushma Malik

Keyword(s):

Metabolic Disorders ◽

Skin Diseases ◽

Febrile Illness ◽

Menkes Disease ◽

Female Child ◽

Severe Form ◽

Cutis Laxa ◽

Facial Features ◽

Elastic Tissue ◽

Tissue Abnormalities

Cutis Laxa (CL) / generalized elastolysis / dermatomegaly is a heterogeneous group of disorders which are related to elastic tissue abnormalities. Depending on extent of abnormal elastic tissue, it may be mild or severe. Severe form presents with loose, inelastic, wrinkled skin resembling ill tted suit. Infant has characteristic facial features like old man appearance, a hooked nose, a short columella, a long upper lip with long philtrum, and everted lower eyelids. CL is categorised as congenital or acquired and the inheritance can be autosomal dominant or recessive, or X linked. Occasionally a few metabolic disorders like Menkes disease, disorders of glycosylation are associated with Congenital CL. Acquired cutis laxa has developed after a febrile illness and various inammatory skin diseases. Here we present a case of a full-term SGA (small for gestational age) female child born with features of CL.

Download Full-text