Question

why is a tissue specific transcription factor important for tissue specific responses to inductive signals?

Answer 1

Tissue specific interaction:

There are different types of organs present in the body, each organ are so complex that are made of different types of tissue types.

Example: Vertebrate eye, light get transmitted through corneal tissue, focused by lens tissue and finally reaches the retinal tissue.

Different tissue type in the organ coordinates with each other to perform a particular function.

Coordination between tissue types can be changed, by the cells present adjacent to them, by which shape, mitosis or the fate of cell is changed.

This type of interaction between the tissue types is called as proximate interaction or induction.

There are 2 components for inductive interaction

1. Inducer – signal is produced by one cell that changes the behaviour of the other cell.
2. Responder – The tissue which responds to the signal

Tissue specific transcription factors:

Gene regulatory networks control the expression of genes in specific tissue types.

Tissue specific transcription factors play major role in producing the signals by initiating transcription. These specific transcription factors are present in only specific tissue types that can bind to the particular DNA site to produce the signal.

If the specific transcription factors are absent, inhibits the transcription and the inducer signal will not be produced.

Tissue specific inducers:

• Signals cannot induce all tissues types. For example: optic vesicle form Xenopus Laevis if placed in an ectopic location (different from the place it has formed) under the head ectoderm, it induces the ectoderm to form lens tissue.
• If the optic vesicle is placed under the ectoderm of abdomen of the same organism, it does not respond.
• Thus signals produced by one tissue can have effect only on the specific tissue type present in that organ.
• This ability to respond to specific signal is called as the competence.
• Competence is the actively required condition, for example: in the mammalian eye formation Pax6 protein is important for the ectoderm that responds to the optical vesicle to form lens.
• This Pax6 protein is not found in any other ectoderm, thus it cannot respond to signals produced even if the particular tissue type is placed near them.

Optic vesicle is the inducer, specific transcription factors in the optic vesicle induces it to produce signals that can act on the ectoderm to produce the lens.

Thus specific transcription factors are necessary to induce signals for the specific tissue type.