Developmental Deformity Due to scalloped Non‐Function in Drosophila Brain Leads to Cognitive Impairment

The transcription factor of the Hippo signaling pathway, LmSd, regulates wing development in Locusta migratoria

Scalloped (Sd) is transcription factor that regulates cell proliferation and organ growth in the Hippo pathway. In the present research, LmSd was identified and characterized, and found to encode an N-terminal TEA domain and a C-terminal YBD domain. qRT-PCR showed that the LmSd transcription level was highest in the fifth-instar nymphs and very little was expressed in embryos. Tissue-specific analyses showed that LmSd was highly expressed in the wing. Immunohistochemistry indicated that LmSd was highly abundant in the head, prothorax, and legs during embryonic development. LmSd dsRNA injection resulted in significantly down-regulated transcription and protein expression levels compared with dsGFP injection. Gene silencing of LmSd resulted in deformed wings that were curved, wrinkled, and failed to fully expand. Approximately 40% of the nymphs had wing pads that were not able to close normally during molting from fifth-instar nymphs into adults. After silencing of LmSd, the transcription levels of cell division genes were suppressed and the expression levels of apoptosis genes were significantly up-regulated. Our results reveal that LmSd plays an important role in wing formation and development by controlling cell proliferation and inhibiting apoptosis.

Neuronal Hippo signaling: From development to diseases

Hippo signaling pathway is a highly conserved and familiar tissue growth regulator, primarily dealing with cell survival, cell proliferation, and apoptosis. The Yes-associated protein (YAP) is the key transcriptional effector molecule, which is under negative regulation of the Hippo pathway. Wealth of studies have identified crucial roles of Hippo/YAP signaling pathway during the process of development, including the development of neuronal system. We provide here, an overview of the contributions of this signaling pathway at multiple stages of neuronal development including, proliferation of neural stem cells (NSCs), migration of NSCs toward their destined niche, maintaining NSCs in the quiescent state, differentiation of NSCs into neurons, neuritogenesis, synaptogenesis, brain development, and in neuronal apoptosis. Hyperactivation of the neuronal Hippo pathway can also lead to a variety of devastating neurodegenerative diseases. Instances of aberrant Hippo pathway leading to neurodegenerative diseases along with the approaches utilizing this pathway as molecular targets for therapeutics has been highlighted in this review. Recent evidences suggesting neuronal repair and regenerative potential of this pathway has also been pointed out, that will shed light on a novel aspect of Hippo pathway in regenerative medicine. Our review provides a better understanding of the significance of Hippo pathway in the journey of neuronal system from development to diseases as a whole.