Cockroach midgut peptides that regulate cell proliferation, differentiation, and death in vitro

Area of Science:

• Insect physiology
• Developmental biology
• Molecular endocrinology

Background:

• Insect midgut cell numbers are maintained through homeostasis.
• Midgut size decreases and cell replacement is suppressed during starvation.
• Insect metamorphosis involves significant organ remodeling via cell proliferation, differentiation, and apoptosis, often increasing cell numbers.

Purpose of the Study:

• To isolate and identify peptides from Periplaneta americana midguts that regulate insect cell proliferation and differentiation.
• To investigate the effects of these peptides on insect midgut cells and fat body cells during development.

Main Methods:

• Extraction and fractionation of peptides from 1650 Periplaneta americana midguts using high-performance liquid chromatography (HPLC).
• Testing HPLC fractions for myotropic activity in insect foregut.
• Assessing the effects of HPLC fractions on primary cultures of larval Heliothis virescens midgut cells and a Mamestra brassicae larval fat body cell line.

Main Results:

• Specific HPLC fractions demonstrated significant effects on insect cell behavior.
• Some fractions promoted midgut stem cell proliferation and differentiation.
• Other fractions induced the loss of differentiated columnar and goblet cells.
• Additional fractions stimulated proliferation in larval fat body cells.

Conclusions:

• Peptides derived from Periplaneta americana midguts play a crucial role in regulating insect cell proliferation and differentiation.
• These identified peptides influence both midgut cell dynamics and fat body cell activity.
• The findings contribute to understanding insect developmental processes and may offer targets for future insect control strategies.