A new report from the Institute for Stem Cell Biology and Regenerative Medicine chronicles breach in planarian’s epidermis cause defect in stem cell function and regeneration, providing a new insight into the Planarian’s regenerative abilities.
(Dr. Dasaradhi Palakodeti with his team members, Image Credit: Dhiru Bansal)
Planaria are flatworms that live in fresh water and has the ability to regenerate which is incomparable among different living organisms. Interestingly, if you cut apart an adult planaria into pieces; not to be surprised, almost any piece can form a completely new animal with all organ systems. These entire regeneration events are orchestrated through adult somatic stem cells called as Neoblasts.
A Research group led by Dr. Dasaradhi Palakodeti at the Institute for Stem Cell Biology and Regenerative Medicine (InStem), Bangalore- has reported that breach in epidermis cause defect in stem cell function eventually leading to defect in regeneration. The discovery by inStem biologists was published in the journal Development.
“It would be ideal if we human beings could regenerate our lost tissue or limbs. This could tremendously boost human health. For the same, it is of paramount importance to understand the process of regeneration,” said Dhiru Bansal, Ph.D. student and first author of this paper.
Dr. Palakodeti’s lab is working on to understand the role of RNA binding proteins in regeneration. Interestingly, his group came across a protein PABPC2 during analysis, which drew their attention to study this protein for two main reasons. First, PABPC is a universal protein present in eukaryotes. It is important for protein synthesis, however, their mechanism and role in regeneration is not known. Secondly, it was a novel protein not reported so far in planaria.
To study the role of pabpc2 gene in regeneration, inStem researchers performed knockdown (a way to make gene non-functional) experiment. They fed the planarians with dsRNA specific to pabpc2 to knock down (KD) the gene. Planarians with pabpc2 KD showed the defect in wound closure and stem cell function due to epidermal defects compared to wild-type.
“In the current study, we have shown the role of the epidermis in providing instructive cues essential for Neoblasts function critical for planarian regeneration. These events essential for wound healing in planaria, such as epidermal migration to cover the wound surface is also observed during the cutaneous wound healing in mammals. Similarly, mobilization of proliferating stem cells (Neoblasts) to the site of injury, which is critical for planarian regeneration, has also been shown to be essential for tissue regeneration in mammals,” said the study leader.
It is unclear in the stem cell field how the environments surrounding the stem cell, which constitute non-stem cells, regulate stem cell function. “Our study uncovered how the organization of the epidermal cells during planarian regeneration is crucial for regulating the stem cell function,” said Dr. Palakodeti.
“Regeneration is often synonymous to stem cells and most of the studies focus on understanding factors responsible for stemness. This study is unique as we identified how a non-stem cell regulates stem cell function. Non-stem cells direct stem cells to respond based on cues,” said Dhiru Bansal.
Dr. Palakodeti’s team have also explored how an ubiquitously (most of the tissues) expressed protein could specifically affect only certain cell types establishing the varied role of the protein in different cell types -critical for some while redundant for other cell types.
This study opens up a new possibility to explore the new role of non-stem cells in regulating stem cells. Skin is often considered for its protective function but this study highlights a much more important role skin can play. It will be interesting to see if these features are also conserved in other organisms.