5. What is collagen ?
A fibrous protein
Most abundant
protein in human
body(25-30% of total
protein content)
Forms major part of
extracellular matrix
and connective
tissues like dermis of
skin cornea bones,
tendons, cartilage,
and vessels
Forms 80% of dry wt.
of dermis
7. CLASSIFICATION OF COLLAGEN
Atleast 28 types of Collagen coded by 42 different genes.
such as Collagens I, II,III,IV,V,VI,VII………..XXVII,XXVIII .
TYPES CODING GENES
I COL1A1,COL1A2
II COL2A1
III COL3A1
IV COL4A1,COL4A2,COL4A3
COL4A4,COL4A5,COL4A6
. .
. .
XXVIII COL28A1
As per their length and number of collagenous and non-collagenous domain
and architectural contribution in various tissues ,four different classes of
collagens.
8. MAJOR CLASSES OF COLLAGEN
FIBRILLAR : I ,II ,III ,V , XI , XXIV and XXVII
NETWORK FORMING : IV , VIII , X
TRANSMEMBRANE : XXIII , XXVII
ANCHORING FIBRIL : VII
9. STRUCTURE OF COLLAGEN
A compact triple helix : 3 alpha chains coiled
around each other to form rod-like structure of
dimension 1.5 * 300 nm
Type1collagen is the prototype (alpha1)2 alpha2
The triple helix is largely explained by the unusual
amino- acids composition such as Proline ,
Hydroxyproline
Each alpha chain comprises of approx.1000
amino acids
with a characteristic repeat sequence Gly-X-Y
X is frequently Proline,Y is often Hydroxyproline
or
hydoxy lysine
12. FUNCTION OF COLLAGEN
As a part of extracellular matrix ,maintains tissue architecture
Supports the epidermis & DEJ with underlying dermis
Maintains the basement membranes of various organ systems like
respiratory,gastrointestinal,urogenital ,etc.
Supports the endothelium ,facilitate adhesion of platelets during
vascular injury
Forms a major part in the architecture of musculoskeletal system
like tendons ,ligaments,cartilage and bones
Maintains the transparency of lens in eye and supports the stroma
of cornea and vitreous humor
13. BIOSYNTHESIS OF COLLAGEN
Intracellular steps:
1. Translation of pre-pro chains on the ribosomes
of the rough endoplasmic reticulum
2. Cleavage of the signal sequence
3. Hydroxylation of selected prolyl and lysyl
residues
4. Glycosylation of some hydroxylysyl residues
5. Formation of intrachain disulfide bonds
6. Formation of triple helices
14. EXTRACELLULAR MODIFICATIONS
. Cleavage of peptide extensions by specific
proteases
Fibril formation
3. Cross-linking of collagen fibrils by deamination of
hydroxylysine and lysine residues to give aldhehydes,
followed by cross-link formation by reaction of either
(a) 2 aldehydes or (b) 1 aldehydes and
1 -amino group on adjacent molecules
15.
16.
17.
18. APPLIED ASPECTS OF COLLAGEN
DISORDERS DUE TO DEFICIENT OR
ABNORMAL COLLAGEN SYNTHESIS :
1.synthesis enzymes deficiency 2. mutation of
coding genes
DISORDERS DUE TO EXCESS COLLAGEN
SYNTHESIS AND ACCUMULATION
PLACE OF COLLAGEN IN AESTHETICS AND
CLINICAL DERMATOLGY
19. DISORDERS DUE TO
DEFECIENCY OR DEFECTIVE
SYNTHESIS
SCURVY : Due to
def. of Vit.C ,the
hydroxylation step
fails.Vit.C acts as
coenzyme for prolyl
hydroxylase and lysl
hydroxylase
20. MENKES
DISEASE
X linked disorder
associated with
copper deficiency
Lysyl oxidase
requires copper for
proper function. This
enzyme cross-links
tropocollagen into
strong collagen
fibrils.
Lead to weakened
bones and cartilage
21. OSTEOGENESIS IMPERFECTA
Also called brittle bone disease, inherited as AD disorder
due to a lack of type I collagen.
90% of cases due to mutations in the COL1A1 or COL1A2 genes.
A least nine different types of OI.
Type I ( most common type ): Collagen is of normal quality but produced in insufficient
quantities. Associated with easy fractures,Slight spinal curvature,Loose joints ,Poor
muscle tone Discoloration of the sclera
Type II (the most lethal) ; Collagen is not of a sufficient quality or quantity.
Severe respiratory problems due to underdeveloped lungs
Severe bone deformity and small stature .Most cases die within the first year of life
due to respiratory failure or intracerebral hemorrhage
Type III ( progressive and deforming) : Enough collagen is made but it is defective.
Bones fracture easily, sometimes even before birth Bone deformity, often severe
Respiratory problems possible Short stature, spinal curvature and sometimes barrel-
shaped rib cage Triangular face ,Loose joints ,discoloration of sclera
Type IV : deforming, but with normal sclerae most of the time
22.
23. ehlers danlos syndrome
13 types of Ehlers-Danlos syndromes, with a
significant overlap in features.
Classical EDS
extremely elastic , fragile skin and bruises easily
wide atrophic scars (flat or depressed scars)
joint hypermobility. and spheroids (fat-containing cysts on forearms
and shins)
Hypermobile EDS
joint hypermobility affecting both large and small joints
recurrent joint dislocations and subluxations ,
soft, smooth and velvety skin with easy bruising
chronic pain of the muscles and/or bones
Dermatosparaxis EDS
extremely fragile skin leading to severe bruising and scarring
saggy, redundant skin, especially on the face
Brittle Cornea Syndrome (BCS) characterized by thin cornea, early
onset progressive keratoglobus and blue sclera
24. Vascular EDS
thin, translucent skin ,fragile and bruise easily
Arteries and certain organs such as intestines tend to
rupture.
short stature; thin scalp hair; and large eyes thin nose, and
lobeless ears.
Joint hypermobility confined to the small joints .
Other common features include club foot; tendon and/or
muscle rupture; acrogeria
Kyphoscoliosis EDS -
severe hypotonia at birth, progressive scoliosis (present from birth),
scleral fragility , unusually small corneas; and osteopenia (low
bone density).
"marfanoid habitus" characterized by long, slender fingers
(arachnodactyly); unusually long limbs; and a sunken chest (pectus
excavatum) or protruding chest (pectus carinatum)
25.
26. Genetic mutation of some specific collagens
Collagen VII (AD/AR) : DYSTROPHIC EPIDERMOLYSIS BULLOSA
EPIDERMOLYSIS BULLOSA ACQUISITA
BULLOUS SLE
COLLAGEN XVII (AR) : JUNCTIONAL EPIDERMOLYSIS BULLOSA
COLLAGEN TYPE IV( BASEMENT MEMBRANE DISORDERS)
alpha3 chain mutation or antibody: GOOD PASTURE SYNDROME
alpha5 chain mutation or antibody : ALPORT SYNDROME
28. DISORDERS OF EXCESS SYNTHESIS AND
DEPOSITION OF COLLAGEN
1 . Keloids and hypertrophic scars
TGF-β signaling pathway
Presence of α1-globulin inhibits
collagenase
2. Dermatofibroma
3. connective tissue collagenoma
a/w increased collagen synthesis with
vertical orientation
multiple papular connective tissue nevus
especially on trunk and upper extremeties
4.SCLERODEMA and other autoimmune
connective tissue disorders
29. PLACE OF COLLAGEN IN AESTHETICS AND COSMETIC
DERMATOLOGY
The advent of various aesthetics procedures has changed the face of Modern
Dermatology
Procedures commonly in vogue are augumentation/voluminizing by Fillers ,
dermabrasion, chemical peeling, BOTOX treatment , liposuction ,etc.
Of note fillers in the form of hyaluronic acid ,PMMA, PLLA and Collagen are
being used to treat fine lines and coarse wrinkles
Collagen fillers in form of human collagen ,COSMODERM and COSMOPLAST .
Collagen also used as a gel in wound healing and as a scaffold for bone graft
Hydolysed collagen is used as a supplement to promote healthy skin and bones.
30. AGEING ?......... WHY?
THE CAUSE :
1.FAILURE OF INTRINSIC ANTIOXIDATIVE MECHANISM
2. ACCUMULATION OF REACTIVE OXYGEN SPECIES
3. TELOMERE SHORTENING
4. DECREASED SYNTHESIS AND INCREASED DERADATION OF
COLLAGEN
Visible skin ageing occurs due to collagen degradation because of imbalance
between MMPs/COLLAGENASES and synthesis of collagen
We can only fantasize to reverse ageing like the reverse ageing of BENJAMIN
BUTTON of the movie “THE CURIOUS CASE OF BENJAMIN BUTTON “
Human efforts can only delay the Inevitable – senescence onto death