The extracellular matrix of the nematode Caenorhabditis elegans : a model to study the role of cell-matrix interaction in animal development.
Access changed 1/17/23
This study is to address the role of extracellular matrix (ECM) in animal development. During development, cells have to gain positional or environmental information either from other cells or their environment. The ECM is located in outside of tissue cells and provide environmental information to lead the proper growth in timely and spatial manner. I was interested in studying how a protein motif in ECM protein plays important role in tissue formation. I focused on UNC-52/perlecan, a proteoglycan ECM molecule, because it contains two RGD (Arg-Gly-Asp) motifs in their domains. The mutations in two RGD motifs showed that the removal of a motif in RGD2023 position resulted in embryonic lethality, while a point mutation, RGD to RGE, produced viable offspring with movement and cell migration defects. Then, I moved to my attention to a cytoplasmic protein TLN-1/talin, a linker protein connects cell-ECM interaction to cytoskeleton. I created a point mutation in a very important residue D400 in the head domain, which is known for binding to βPAT-3 integrin cytoplasmic in dense bodies. The TLN-1 mutation on D400R caused defective cytoskeletal organization and abnormal dense bodies. The βPAT-3 integrin, an αβ heterodimeric cell surface receptor for the extracellular matrix (ECM). The NPxY (Asn-Pro-x-Tyr) motif on the βPAT-3 cytoplasmic tail was changed to NPVE804, mimicking constitutive activation of tyrosine (Y) in the NPVY, which is a conserved phosphorylation motif that binds to the phosphotyrosine binding (PTB) domain of a cytoplasmic protein. The transgenic rescue animals displayed defects in muscle morphology, gonad migration, high male number, and tail morphology. Further analyses revealed that males from pat-3(Y804E) transgenic mutant and him-4/hemicentin share similar phenotypes such as abnormal gonads and unsuccessful mating, suggesting that the wild-type function of HIM-4 is to prevent phosphorylation of NPxY motif. Here, my study reports the role of the RGD motif, in UNC-52/perlecan is essential for survival. Such motif is essential for delivering the environmental information to the cell, which is mediated by βPAT-3 integrin NPxY motif, TLN-1, and actin cytoskeleton.