Cytoplast
From Wikipedia, the free encyclopedia
A cytoplast is a cellular structure made up of the cytoplasm and plasma membrane, but not a nucleus. It is commonly used in cell biology to describe enucleated cells that retain functional cytoplasmic components. Cytoplasts play a crucial role in Cell fusion, reprogramming, and Somatic cell nuclear transfer or SCNT for short. Recent studies have also shown that cytoplasts from human embryonic stem cells (hESCs) have reprogramming factors that can help turn somatic cells into pluripotent cells(stem cells that can differentiate into any cell type) without needing genetic modifications.[1]
The concept of cytoplasts emerged from early studies on cell division and nuclear-cytoplasmic interactions. The term gained popularity in the 1970s and 1980s with advancements in cell fusion techniques and nuclear transfer experiments.
- Early recognition of cytoplasts: The cytoplast concept can be traced back to early studies of organelle biogenesis in eukaryotic cells. The understanding of cellular compartments and their functions grew significantly with the development of Electron microscopy and sub-cellular fractioning techniques.[2] These advancements enabled scientists to isolate and study cytoplasmic components separately from the nucleus.
- Porter and McNiven’s cytoplast concept: In the 1980s, Porter and McNiven introduced the idea that the cytoplasm, even in the absence of a nucleus, functions as an organized “cytoplast”, structured integrated by a Cytoskeleton.[3]
- Somatic Cell Nuclear Transfer (SCNT) and Cloning: Cytoplasts later became central to nuclear reprogramming when it was found that oocyte cytoplasts could reprogram somatic nuclei, leading to successful cloning in the famous Dolly the sheep experiment in 1996. This experiment proved that cytoplasmic factors in enucleated oocytes played a key role in altering nuclear function and resetting cell identity.[4]
- Stem cell research and cytoplast reprogramming: Advances in stem cell research further showed the significance of cytoplasts. It was demonstrated that cytoplasts from hESCs arrested at metaphase contain essential pluripotency factors, enabling reprogramming of somatic cells.[2]
- Organelle biogenesis and cellular organization: Research into organelle inheritance broadened the understanding of cytoplasts, showing that membrane-bound structures like the Golgi Complex, Endoplasmic reticulum, and Mitochondria could function and reorganize within enucleated cells.[5]
- Mechanical properties of cytoplasts: Recent studies indicate that cytoplasts retain mechanical stiffness even after enucleation, suggesting that the Actomyosin cytoskeleton plays a more dominant role in cellular mechanics than previously thought.[6]
These historical developments have established cytoplasts as essential tools in Cell biology, Regenerative medicine, and Cloning, leading to their continued use in many cellular studies.
Structure
A cytoplast consists of
- Cytoplasm – The fluidic interior containing organelles essential for cellular metabolism.
- Cell membrane – The outer lipid bilayer that maintains cellular integrity.
- Cytoskeleton – A network of Microtubules(MTs), Actin filaments, and intermediate filaments that provides mechanical support and helps in cellular signaling.