The pro-inflammatory interleukin-1 is a major cytokine that increases the cutaneous levels of POMC mRNA and peptides, and MSH receptors. The CRH or POMC systems undergo a stimulation of expression of all their components, on being exposed to ultraviolet radiation. In addition, the corresponding receptors, also undergo a stimulation of expression (Slominski et al, 2000, Pp. 979 -1020 ).
The cutaneous POMC gene’s molecular characterisation reveals mRNA forms that resemble those to be found in the pituitary, whose expression is conjoined with that of the shorter variants. The cutaneous expression of receptors, in respect of POMC peptides is functional in nature. It includes, MC1, MC5 and µ-opiate. However, the peptides from the MC1 class are found to have the greatest predominance. POMC peptides and CRH have significant effect on the skin’s pigmentation, and immune and adnexal systems. These effects bring about stress – neutralising activity and the maintenance of skin integrity, thereby curtailing disturbances of internal homeostasis (Slominski et al, 2000, Pp. 979 -1020 ).
The cutaneous expression of the CRH/POMC system is accordingly, well organised and encodes mediators and receptors, in a manner that is analogous to what occurs in the hypothalamic – pituitary – adrenal or HPA axis. Furthermore, the POMC and CRH skins system of seem to produce a function, which appears to be akin to that of the HPA axis. This function results in a cutaneous localised response that counterbalances deleterious stimuli and their consequent immune reactions (Slominski et al, 2000, Pp. 979 -1020 ).
Proopiomelanocortin produces melanocortin peptides, subsequent to undergoing sequential cleavage. An example of these peptides is provided by the adreno – adrenocorticotrophin or ACTH. In addition, this cleavage generates the hormones that stimulate the melanosite proteins, and the opioid receptor ligand β – endorphin. α – MSH peptide is responsible for the stimulation of melanocortin 4 receptor in the human brain, which plays a major part in the control of food intake. The brain melanocortin 4 receptor derives from the MC4R. As such, the secretion of α – MSH suppresses appetite and influences hair pigmentation. Consequently, defects in POMC functionality, could result in obesity and change in skin pigmentation. For instance, such defects can be deemed to be the cause of pale skin and red hair in Caucasians (Coulston & Boushey, 2008, P. 359).
Defects in POMC processing result in obesity; consequently, size of the body is dependent on the locus of POMC. In a research study, two siblings with complex POMC gene mutations, exhibited severe early-onset obesity. In addition, they had congenital ACTH deficiency and red hair pigmentation (Rimoin et al, 2007, P. 2130).
Defects in the POMC gene’s varied functions lead to intricate medical ailments. For instance, deficiency in corticotropin, severe early onset obesity and hypopigmentation. Till date, patients suffering from total loss of function mutations of the POMC gene have exhibited obesity and adrenal insufficiency. However, red hair pigmentation has been seen to depend on ethnic background (Beals et al, 2008, P.59).
Works Cited
Beals, Philip R., et al. Genetics of Obesity Syndromes. Oxford University Press US. 2008.
Coulston, Ann M. and Carol J. Boushey. Nutrition in the Prevention and Treatment of Disease. 2nd Edition. Academic Press, 2008.
König, Simone, Thomas A Luger and Thomas E Schol. "Monitoring neuropeptide-specific proteases: processing of the proopiomelanocortin peptides adrenocorticotropin and α-melanocyte-stimulating hormone in the skin." Experimental Dermatology (31 Jul 2006, P 751-761): Volume 15 Issue 10. Blackwell Munksgaard.
Rimoin, David L., et al. Emery and Rimoin's principles and practice of medical genetics. Elsevier Health Sciences, 2007, P 2130.
Slominski, Andrzej, et al. "Corticotropin Releasing Hormone and Proopiomelanocortin Involvement in the Cutaneous Response to Stress." Physiological Reviews (July 2000, PP. 979-1020 ): Vol. 80, No. 3, American Physiological Society.