acinar cell differentiation

Definition

Target type: biologicalprocess

The epithelial cell differentiation process in which a relatively unspecialized cell acquires specialized features of an acinar cell, a secretory cell that is grouped together with other cells of the same type to form grape-shaped clusters known as acini. [GOC:dph, GOC:tb]

Acinar cell differentiation is a complex process that involves the transformation of undifferentiated progenitor cells into mature acinar cells, the primary functional units of exocrine glands, like the pancreas and salivary glands. This differentiation is tightly regulated by a cascade of signaling pathways and transcription factors, ensuring the proper development and function of these glands.

Here's a detailed breakdown of the process:

1. **Commitment to the Acinar Lineage:** Undifferentiated progenitor cells residing within the developing gland receive signals that trigger their commitment to the acinar cell fate. These signals can include growth factors like epidermal growth factor (EGF) and fibroblast growth factor (FGF), as well as transcription factors like pancreatic and duodenal homeobox 1 (PDX1) and neurogenin 3 (NGN3).

2. **Morphological Changes:** As the cells commit to the acinar lineage, they undergo significant morphological changes. They acquire a polarized shape, with the apical region facing the lumen of the gland and the basolateral region facing the surrounding tissue. The apical region develops a specialized structure called the zymogen granule, which stores digestive enzymes.

3. **Expression of Acinar-Specific Genes:** Concurrently with morphological changes, the cells begin to express genes specifically required for acinar cell function. These include genes encoding digestive enzymes like amylase, lipase, and protease, as well as genes involved in the synthesis and secretion of these enzymes.

4. **Formation of Acinar Units:** The differentiating acinar cells assemble into functional units, forming clusters called acini. These acini are surrounded by a network of blood vessels and ducts, facilitating the delivery of nutrients and the removal of secreted products.

5. **Regulation of Differentiation:** The entire process of acinar cell differentiation is regulated by a complex interplay of signaling pathways and transcription factors. These pathways involve molecules like Wnt, Notch, Hedgehog, and TGF-beta, which influence the expression of key transcription factors that orchestrate the expression of acinar-specific genes.

6. **Terminal Differentiation:** The final stage of acinar cell differentiation involves the complete development of the zymogen granules and the establishment of the mature acinar cell's ability to synthesize and secrete digestive enzymes in response to appropriate stimuli. This process is crucial for the normal functioning of the exocrine gland.

7. **Regulation of Acinar Cell Function:** Even after reaching terminal differentiation, acinar cells can be influenced by various factors. Hormones like cholecystokinin (CCK) and acetylcholine stimulate enzyme secretion, while factors like stress and inflammation can alter their activity.

Overall, acinar cell differentiation is a carefully orchestrated process that ensures the development and function of exocrine glands. This process involves a series of tightly regulated steps, involving cell commitment, morphological changes, gene expression, and the assembly of functional units. Understanding the complexities of this process is crucial for comprehending the pathogenesis of diseases that affect exocrine glands, such as pancreatitis and cystic fibrosis.'
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